Atrioventricular Septal Defects and Atrioventricular Valve Anomalies

Friedberg, Mark K.; Silverman, Norman H.

doi:10.1007/978-1-84800-064-3_8

Mark K. Friedberg MD³ &
Norman H. Silverman MD, DSc (Med), FACC, FASE, FAHA, FCP(SA)⁴

3052 Accesses

Abstract

Transesophageal echocardiography plays a major role during the surgical intervention of congenital pathologies that affect the atrioventricular junction and atrioventricular valves. The prebypass examination can refine the planned surgical procedure, while the postbypass assessment can detect clinically significant residual findings that otherwise would not have been identified, thereby prompting a return to cardiopulmonary bypass and subsequent reintervention. This chapter focuses on the morphologic features and corresponding echocardiographic findings, as displayed by transesophageal imaging, of the most common congenital anomalies that involve the atrioventricular junction. Particular emphasis is placed on atrioventricular septal defects and malformations affecting the atrioventricular valves.

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Atrioventricular Septal Defects

Echocardiographic assessment of left to right shunts: atrial septal defect, ventricular septal defect, atrioventricular septal defect, patent arterial duct

Article Open access 01 March 2018

Keywords

Introduction

Transesophageal echocardiography (TEE) has had a major impact on surgery of the atrioventricular (AV) valves in children [1]. Prebypass information obtained by TEE may alter the planned surgical procedure, while postbypass TEE can detect clinically significant residual findings that would otherwise not have been identified, thereby prompting a return to cardiopulmonary bypass and subsequent reintervention [2, 3]. TEE has also expanded the anatomic and hemodynamic assessment in patients with congenital heart disease (CHD), particularly in those with challenging or limited transthoracic echocardiographic examinations (TTE) such as adults, patients with surgical dressings, or poorly characterized studies [4]. In view of excellent transthoracic imaging in children, the principal use of TEE at most institutions largely centers around the intraoperative evaluation.

This chapter reviews the pertinent anatomic and TEE features of the most common congenital lesions affecting the AV junction, with particular emphasis on AV septal defects and pathology of the AV valves. The reader is encouraged to refer to Chap. 4 for a detailed discussion regarding TEE evaluation of AV valves and related structures in the normal heart.

Atrioventricular Septal Defects

Atrioventricular septal defects (AVSDs), also termed AV canal or endocardial cushion defects, result from abnormal development of the embryologic endocardial cushions. They occur in 0.19 per 1,000 live births, constituting 4–5%of all congenital heart lesions. The endocardial cushions play an integral role in the formation of the atrial and ventricular septa as well as both AV valves. Thus an abnormality of endocardial cushion development can be expected to affect a number of intracardiac structures.

Morphology

In AVSD, atrial and ventricular septation are deficient, and rather than separating into distinct mitral and tricuspid orifices, the AV junction remains common (Fig. 8.1). This lesion represents a spectrum of anomalies that can be further divided into complete and incomplete (partial) forms of AVSD. In complete AVSD, the inferior portion of the atrial septum and the posterior portion of the ventricular septum are absent, resulting in a “scooped out” appearance to the ventricular inlet, with large contiguous atrial (ASD) and ventricular septal defects (VSD) that allow shunting to occur at both levels. In addition, one large common AV valve is present. This is the most common form of AVSD in children. In the case of incomplete AVSDs, there is partial fusion between the superior and inferior bridging leaflets to form two separate AV orifices. When the AV valvar leaflets adhere to the ventricular septum and completely prevent any ventricular communication, an ostium primum ASD results. If on the other hand the leaflets attach to the ventricular septum but do not completely obstruct communication between the ventricles, then a small VSD can be present. Rarely, a form of incomplete AVSD is produced when the AV valve leaflets adhere completely to the inferior portion of the interatrial septum, preventing any atrial shunting but allowing ventricular shunting to occur. This is known as a VSD of the AV canal type. Regardless of whether an AVSD is complete or incomplete, there is a common anatomic feature shared by both: a large defect in the AV septum, extending above and below the crux of the heart. What differentiates the complete and incomplete forms is the degree of septation of the AV valves, in addition to the manner and extent to which the AV valve(s) attaches to the crest of the ventricular (or atrial) septum, thereby determining whether atrial or ventricular shunting (or both) can occur. Other forms of incomplete AV canal defects include a common atrium (in which no atrial septum is present), and isolated cleft left AV valve (LAVV or mitral valve), in which no atrial or ventricular communication is present.

The terminology used in the classification of AVSDs has been the subject of confusion and even controversy [5]. This is related to the fact that nomenclature such as intermediate and transitional has also been applied to describe variant forms of the complete and partial defects. To complicate matters further, in many cases these terms have been used interchangeably. When considered as different entities, an intermediate AVSD refers to a variant of the complete form of the defect in the setting of a common AV valve annulus and two distinct AV valvar orifices separated by a tongue of tissue. These types of defects are characterized by a primum ASD and a nonrestrictive VSD. From a physiologic perspective, these defects are no different than the common type of complete AVSD. A transitional defect has been regarded a variant of the partial form of AVSD. This is the defect characterized by two distinct AV valve annuli, a primum ASD, a cleft LAVV, and a small inlet VSD, frequently restrictive in nature, due to partial obliteration of the ventricular communication by valvar tissue. The physiology of this defect mimics that of the typical partial AVSD (ostium primum ASD and cleft LAVV). It has been argued, however, that categorization of defects into these variants is unnecessary and only two main forms of the defect, complete and partial should be recognized [5, 6]. The main distinction should then relate to two aspects of the anatomy: (1) arrangement of the valvar leaflets relative to the AV orifices and (2) relationship of the bridging leaflets of the common valve and the septal structures. For the purpose of this chapter the classification scheme of complete and partial defects will be used.

In AVSD, there is always a common AV valve annulus (Fig. 8.1) [7]. In the complete defect, the common AV valve resembles its embryonic form and has five leaflets (Fig. 8.2). The superior bridging leaflet, a derivative of the embryonic superior endocardial cushion, and the inferior bridging leaflet, a derivative of the embryonic inferior cushion, straddle the atrial and ventricular septa and cross the area normally occupied by the AV septum. A mural (lateral) leaflet in the left side of the AV valve orifice completes the left component of the common AV valve. The right side of the common AV valve consists of the two components of the bridging leaflets as well as the anterior and posterior (mural) leaflets. The meeting point or zone of apposition between the left components of the bridging leaflets is the so-called ‘cleft’. This has also been considered to represent a commissure and alternatively may be referred to as such [8].

The Rastelli classification of complete AVSDs, based on the morphology of the superior bridging leaflet, degree of bridging, and its chordal attachments, was originally considered to have prognostic implications. Although now less important surgically, this scheme is still widely used (Fig. 8.3) [9]. In our previously published experience of Rastelli type A AVSD, which accounted for 89 % of the complete form of AVSD, the superior bridging leaflet attaches to the ventricular septum. In that report Down syndrome was present in 58 % of the patients with this type of lesion but not with the other complete forms of AVSD [10]. In Rastelli type B, which accounted for 2 % of cases, the superior bridging leaflet attaches to a septal papillary muscle on the right side of the ventricular septum. However, it is often difficult to differentiate between the Rastelli types A and B. In Rastelli type C, which accounted for 9 %, the least developed or most primitive form of AVSD, the superior bridging leaflet extends to the anterior papillary muscle within the right ventricle. In this arrangement there are no chordal attachments to the septum and the freestanding right ventricular papillary muscle supports the right component of the superior bridging leaflet [11].

A number of other morphologic characteristics are present in AVSD. The positions of the left ventricular papillary muscles are rotated counter-clockwise (when viewed from the apex) due to counter-clockwise rotation of the LAVV commissures. The anterolateral papillary muscle is situated more medially at ‘three o’clock’, and the posteromedial papillary muscle is situated more laterally at ‘five o’clock’, compared with their normal positions at ‘four o’clock’ and ‘seven o’clock’, respectively as viewed from the parasternal left ventricular short axis view by TTE (Fig. 8.2) [10]. Papillary muscle rotation and approximation may cause a functionally parachute LAVV. Therefore, recognition of both papillary muscles within the left ventricle is important because repair of the LAVV may create an acquired parachute mitral valve deformity. In the normal heart the aortic valve is wedged between the mitral and tricuspid valves. In contrast, in AVSD, the aorta is “sprung” anteriorly and superiorly due to the lack of two separate AV orifices between which the aortic valve is normally situated (Fig. 8.2) [12]. These morphologic features, along with a discrepancy in the length of the left ventricular inlet and outlet (Fig. 8.4), create elongation and narrowing of the left ventricular outflow tract (LVOT), producing the so-called ‘goose-neck’ deformity characteristic of AVSDs initially described by its angiographic appearance.

Shunting of blood in AVSD depends upon the attachment of the AV valve(s) to the septum and the direction of regurgitant valve jets. In diastole shunting is largely atrial, whereas in systole it is largely between the ventricles. If the valve leaflets adhere to the crest of the ventricular septum, as they do in ostium primum ASD, then the shunting is interatrial, whereas if the leaflets adhere to the interatrial septum as they do in isolated VSDs, the shunting is interventricular (Fig. 8.5). A left ventricular to right atrial shunt can be present, and less frequently in some cases, depending on the hemodynamics, right ventricular to left atrial shunts can be seen. These shunts are compounded by additional left ventricular to left atrial and right ventricular to right atrial regurgitant jets.

In most cases, atrial level shunting is holodiastolic in nature and occurs in the left-to-right direction, however, flow reversal (e.g., right-to-left shunting) may occur briefly during the cardiac cycle related to associated pathology and hemodynamic status. The magnitude of shunting at the ventricular level is primarily determined by the size of the defect and the pulmonary vascular resistance. In regards to flow direction, left-to-right ventricular level shunting typically occurs during systole and is enhanced by a low pulmonary vascular resistance. Bidirectional shunting with right-to-left shunting in diastole, or predominant right-to-left shunting are seen in the setting of increased pulmonary vascular tone. Right ventricular to left atrial shunting in systole, although uncommonly seen, may contribute to arterial desaturation.

Pathophysiology

AVSDs represent a group of lesions that result in a volume load to the heart. The presence of an intracardiac communication(s) in these defects typically leads to left-to-right shunting and increased pulmonary blood flow. The concomitant presence of AV valve regurgitation further exacerbates the ventricular volume overload. In the case of complete defects, the symptomatology is magnified due to shunts both at atrial and ventricular levels, frequent ventriculo-atrial shunts, and the presence of pulmonary hypertension. The elevated pulmonary artery pressure also imposes a pressure load on the right ventricle. Due to these factors, patients with complete AVSDs are generally in significant congestive heart failure; these symptoms account for the fact that complete AVSDs require corrective surgery during infancy. In some cases, elevated pulmonary vascular resistance limits left-to-right shunting and in fact, as mentioned, may even lead to predominant right-to-left shunting resulting in cyanosis. In the case of partial defects with a VSD, interventricular pressure restriction across the small defect limits the degree of ventricular left-to-right shunting, thereby minimizing pulmonary overcirculation and volume overload. Nonetheless these patients can still present with congestive symptoms if there is hemodynamically significant LAVV regurgitation. In partial defects without significant LAVV regurgitation, the physiology mimics that of any other atrial level communication, and clinical symptoms might be minimal or absent. In this case, left-to-right atrial level shunting is determined by the relative compliances of the ventricular chambers.

Management Considerations

A number of surgical techniques have been applied to the surgical correction of AVSDs. In complete defects, the goal of the intervention is reconstruction of the common AV valve to achieve two separate and competent AV valves, along with closure of the LAVV cleft, closure of the intracardiac communications, and repair of associated defects. This can be accomplished by a variety of approaches (i.e., single patch, double-patch, and modified techniques) [13–15]. The objectives of the surgical repair in partial AVSDs are to eliminate shunting, in the majority of cases by patch closure of the primum septal defect, and closure of the cleft to create the equivalent of an anterior mitral valve leaflet that coapts well with the posterior leaflet without significant regurgitation or stenosis.

Transesophageal Echocardiography

Preoperative TEE Evaluation

The most common indication for TEE in patients with CHD is for assessment during cardiac surgery [16]. Intraoperative TEE has improved surgical outcomes by providing the surgeon with real-time information about cardiac anatomy and valvular function [3, 17]. TEE can confirm or exclude preoperative transthoracic information and assess the immediate preoperative hemodynamics and ventricular function. In addition, important findings and key anatomic and hemodynamic features can be directly demonstrated to the perioperative providers for immediate review just prior to commencement of the operation. Preoperative TEE may also facilitate the placement of central venous catheters, selection of anesthetic agents, and use of preoperative inotropic support by demonstrating ventricular systolic function and size (refer to Chaps. 3 and 15) [18, 19]. However, in keeping with the recommendations of the Task Force of the Pediatric Council of the American Society of Echocardiography on pediatric TEE, as in the case of all congenital cardiac defects, an AVSD and its anatomical features should be defined completely preoperatively by transthoracic imaging [16]. The prebypass TEE should then confirm the TTE findings. Pertinent points to be addressed by the prebypass TEE include:

The atrial communication(s)
The type and extent of the ventricular communication(s)
Atrioventricular valve morphology and function
Shunting patterns and AV valve regurgitation
Commitment of the AV junction to the underlying ventricular mass and the size of the ventricles (balance)
Associated cardiac anomalies, including patent ductus arteriosus, left superior vena cava to coronary sinus, and coexistent lesions of moderate complexity such as tetralogy of Fallot

In addition, on the prebypass TEE, the operator should search for additional VSDs that might require surgical intervention as these may be easily missed in previous TTE imaging. The echocardiographer should also document the degree of AV valve regurgitation to facilitate comparison with any residual regurgitation after repair.

Intraoperative Imaging

Two-Dimensional Imaging of Complete Defects

As previously mentioned, the preoperative examination should focus on the details of the anatomy, functional assessment of the AV valves(s), and evaluation of associated defects as follows:

The Atrioventricular Septum and Common Atrioventricular Valve

The AV septum is best imaged from the mid esophageal four chamber (ME 4 Ch) view in the axial orientation. Further inferior or superior probe positioning within the mid esophagus, as well as anteflexion/retroflexion, allows optimization of the view and visualization of additional structures such as the LVOT. The ME 4 Ch demonstrates the relationship of the AV valves to each other and to the septa. In this defect, the AV valves insert onto the interventricular septum at the same level (Fig. 8.6, Video 8.1). Septal attachments of the chordae tendineae and papillary muscle apparatus of the LAVV define the ‘cleft’ or commissure between the superior and inferior bridging leaflets. The echocardiographer should assess the anatomical boundaries of the atrial and septal components of the defect. Scanning posteriorly (probe retroflexion) from the ME 4 Ch view defines the posterior limits of the atrial and ventricular components of the septal defect. Locating the crux of the heart (coronary sinus) with retroflexion of the transducer followed by slight anteflexion defines the position of the inferior components of the AV valve as it crosses the septum. The superior component is correspondingly defined in this plane by anteflexing the probe so that the bridging leaflet is observed crossing the anterior aspect of the defect. Anterior angulation of the transducer by cephalad retraction of the probe and further anteflexion from the ME 4 Ch view to a ‘five chamber view’ defines the anterior extent of the septal defects, the relationship of the chordae tendineae to the underlying ventricular septum and the LVOT, and the aortic root.

The morphology of the common AV valve and chordal attachments should be assessed in multiple planes including those displayed by the ME 4 Ch, mid esophageal long axis (ME LAX), TG basal short axis (TG Basal SAX), transgastric two chamber (TG 2 Ch), deep transgastric long axis (DTG LAX), and deep transgastric sagittal (DTG Sagittal) views. The ME 4 Ch view is particularly useful for defining the Rastelli type, although the operator must be cognizant of the scan plane passing through the superior leaflet (Fig. 8.3). This is achieved by pulling the transducer cephalad from this view into the upper esophagus, applying anteflexion and then directing the scan plane slightly posterior by advancing the transducer to the level of the mid esophagus until the superior bridging leaflet is identified. Transgastric and deep transgastric short axis views of the ventricles that display the common AV valve en face, much like a transthoracic subcostal view, also assist in the determination of Rastelli type as well as degree of balance of the AV valve over the ventricles, and attachments of the valve to the left and right ventricular papillary muscles (Figs. 8.3 and 8.7, Video 8.2). Because the plane of the AV junction is oriented more vertically in patients with an AVSD, the true short axis view in this anomaly is obtained using a more sagittal plane, which may require further angulation of the probe, by rotation and anteflexion [10, 20]. It is usually helpful to advance the probe into the stomach, apply anteflexion and then further advance the probe while it is flexed to increase its anterior curvature. The probe may then be gently withdrawn while maintaining anteflexion towards the esophago-gastric junction, until the optimal image comes into view. This “in between” deep transgastric view with multiplane angle between 0° (DTG LAX view) and 90° (DTG Sagittal view) is optimal to display the common AV valve en face (Fig. 8.8, Video 8.3).

There is considerable morphologic and functional variation in the AV valves and their support apparatus. Short axis scanning of the entire AV orifice from a transgastric or deep transgastric plane displays the five leaflets of the common AV valve and the cleft between the left-sided components of the bridging leaflets (Fig. 8.7, Video 8.2). In AVSD, the cleft always points toward the inlet septum (Figs. 8.9 and 8.10, Videos 8.4 and 8.5), while an isolated cleft that is not part of an AVSD points to the LVOT [20–22]. The morphology of the left component of the AV valve should also be examined by imaging in the ME LAX view with the transducer plane at approximately 120⁰ (Fig. 8.11, Video 8.6). The left component of the AV valve may also exhibit a double orifice, which can be identified in the en face view (Fig. 8.12, Video 8.7) [23, 24].

The Interatrial Communication

An ostium primum type atrial septal communication is found in most AVSDs. In a study examining the cross-sectional echocardiographic findings in AVSDs, a primum ASD was identified in nearly all patients (170 out of 171) [10]. Among the entire cohort, 74 % had a complete AVSD and 25 % a partial defect. A single patient had only a VSD component and cleft mitral valve.

The ostium primum ASD can be defined from a number of views, but is best outlined when the atrial septum is perpendicular to the transducer. This can be accomplished in the ME 4 Ch view (approximately 0⁰) by rotating the shaft of the transducer slightly clockwise to focus on the interatrial septum (Fig. 8.13, Video 8.8). The size of the ostium primum defect may vary from very large to extremely small. When the interatrial septum is well formed, it can be defined in the ME 4 Ch view as extending from the interatrial groove down to the lower edge of the inferior rim of the oval fossa. The ostium primum defect extends from the lower edge of the true atrial septum to the conjoined AV valve bridging leaflets inferiorly [10].The junction of the lower end of the atrial septum and an enlarged coronary sinus due to the connection of a left superior vena cava should not be confused with an ostium primum defect, particularly because the two structures are adjacent to each other. The coronary sinus is situated just anterior to the crux of the heart, and an ostium primum defect is located anterior to the coronary sinus. The ostium primum defect can also be identified from the mid esophageal bicaval (ME Bicaval) view with the plane at approximately 90⁰. Shunting across the ostium primum defect occurs during diastole and in most cases flow is laminar and low velocity. Aliasing and higher than expected flow velocities can be seen depending on the size of the defect and relative amount of blood flow across it.

Ostium secundum ASDs are also frequently present (Figs. 8.13 and 8.14, Videos 8.8 and 8.9). In isomerism of the atrial appendages, the atrial septum can be almost completely absent with only a strand of atrial tissue remaining.

The Ventricular Component of the Defect

The ventricular component of the AVSD is displayed best in the ME 4 Ch view where its central portion below the bridging AV leaflets is seen (Fig. 8.15, Video 8.10). Other planes such as the ME LAX, TG Basal SAX, transgastric mid short axis (TG Mid SAX) and the deep transgastric views should also be used (Fig. 8.16, Video 8.11) to assess the ventricular communication(s). Isolated ventricular defects are rare (1 out of 171 patients with AVSDs in series described previously) and have been classified as ‘VSDs of the AV canal type’ (Fig. 8.17, Video 8.12). These differ from true isolated VSDs in the inlet septum (discussed in Chap. 9) in that they are located more posteriorly and have typical associations such as rotated papillary muscles and a cleft in the left component of the AV valve [25]. They can also have chordae from the left AV valve attaching to the crest of the ventricular septum.

The proximity of the VSD to the AV valves and their chordal apparatus may obscure the defect in diastole. Therefore, the ventricular component of the defect is best defined during systole when the AV valve leaflets are closed and the chordal apparatus tensed. During systole, the valve leaflets move away from the ventricular component of the defect exposing the VSD and its relationship to the underlying papillary muscles and/or the ventricular septum. In those situations when the defect is not easily visualized because of dense chordal attachments to the crest of the interventricular septum, flow may still be detected by Doppler color flow imaging (Fig. 8.13, Video 8.8). The atrial component of the defect can be difficult to define when the common AV valve is open, especially if small, as there is complete communication between the atria and ventricles. This may be better appreciated when the valve is closed. Thus, definition of the components of the defect should be performed during the full cardiac cycle.

AVSDs intrinsically have elongation of the LVOT and shortening of the left ventricular inflow, creating inlet–outlet disproportion (Fig. 8.4) as mentioned. This is in contrast to the left ventricle in the normal heart where the inlet and outlet are of equal length. Anterior angulation of the transducer from the deep transgastric window and a multiplane angle of 90⁰ to visualize the aortic root (DTG Sagittal view) demonstrates the ‘gooseneck deformity’ of the LVOT (Fig. 8.18, Video 8.13) [10]. The outflow tract can also be imaged from the ME LAX and ME 4 Ch view with anteflexion of the imaging probe. Chordal attachments of the AV valve leaflets, and in some instances accessory left AV valve tissue can also contribute to LVOT obstruction (Fig. 8.19, Video 8.14).

Commitment of the Atrioventricular Junction to the Ventricles

Usually the right and left portions of the AV junction are equally committed to their respective ventricles, however, preferential commitment to either ventricle can occur in approximately 5–10 % of cases, resulting in left, or more commonly right ventricular dominance (Fig. 8.20) [10, 26]. This is also known as an unbalanced AVSD.

The commitment of the AV orifice to the underlying ventricles by TEE can be defined from the ME 4 Ch view (Fig. 8.21, Video 8.15), but additional views (including the TG Basal SAX and deep transgastric views) provide further comprehensive assessment. Unbalance of AV tissue over the ventricles, ventricular hypoplasia or the presence of a single left ventricular papillary muscle may preclude a biventricular repair. Unbalanced AVSDs are commonly associated with heterotaxy syndromes, particularly right atrial isomerism (asplenia). This is further discussed in Chap. 10.

As this represents an important issue for surgical planning, echocardiographic criteria have been investigated to determine the extent of unbalance in order to discriminate between balanced and unbalanced forms of the defect. This is particularly relevant to settings where the degree of unbalance is not extreme, being readily determined by qualitative assessment. A parameter studied by TTE has been referred to as ‘atrioventricular valve index’ (AVVI) [27].This is obtained from a subcostal left anterior oblique cross section (en face view), where the relationship between the common AV valve and ventricular septum are visualized. The orifice of the common AV valve is traced in diastole and after a line in drawn corresponding to the plane of the interventricular septum, the respective areas of the left and right components are determined. In its initial description, the AVVI was expressed as the ratio of the area of the smaller AV valve component to the larger component. Most recently, a modified AVVI has been used to correlate anatomic type of AVSD and surgical decision-making [28]. For this purpose the index was simplified, being derived by dividing the LAVV area by the total AV valve area. An AVVI of <0.4 was considered to define right dominance and >0.6, left dominance. Although, not formally studied by transesophageal imaging, this index can also be derived from deep transgastric interrogation using the equivalent en face view, allowing for evaluation of balance versus unbalance at the time of surgical intervention.

Two-Dimensional Imaging of Incomplete (Partial) Defects

As indicated, in all forms of AVSD the AV junction consists of a single annulus, but there may be a single valve orifice (the complete form), or two separate orifices (the partial form), formed by a tongue of tissue connecting the two bridging leaflets and dividing the common orifice. Functionally separated AV orifices also occur when only an atrial or ventricular component of the defect is present. An isolated ventricular component of an AVSD occurs only rarely, as previously noted. An isolated atrial component (ostium primum ASD) occurs much more frequently and results from fusion of the bridging leaflets with the ventricular septum. A cleft in the mitral valve, best seen in views that display the valve in its short axis, can be associated with variable degrees of regurgitation.

Partial AVSDs may exhibit redundant tissue prolapsing through the interventricular communication into the right ventricle, also known as tricuspid pouch. This is comprised by connecting tissue between the bridging leaflets and tissue from the superior bridging leaflet and its tensor apparatus [10, 29]. This structure can be seen in the ME 4 Ch view (Fig. 8.22, Video 8.16) and short axis images of the common AV valve from the transgastric and deep transgastric windows, and has an identical appearance to that of tricuspid tissue tags or membranous ventricular septum aneurysm found with perimembranous VSDs. The size of the tricuspid pouch can be quite prominent.

Doppler Evaluation of Defects

The detection of shunting patterns by color flow Doppler is important for the surgical repair as well for prognosis [10, 30, 31]. This applies to both the evaluation of intracardiac communications and valve regurgitation. Color flow mapping facilitates the assessment of intracardiac shunting (Figs. 8.14, 8.16, and 8.23, Videos 8.9 and 8.11) and is particularly helpful in the assessment of flow when there is limited potential for interventricular shunting under the superior bridging leaflet (restrictive VSD) in the setting of a partial AVSD (Fig. 8.13, Video 8.8). The peak velocity of the jet across the ventricular level shunt, as obtained from spectral Doppler interrogation, represents the pressure gradient between the ventricles in the absence of right ventricular outflow tract obstruction (RVOTO). This can be used to estimate right ventricular and pulmonary artery pressures by applying the simplified Bernoulli equation as follows:

Right Ventricular Systolic Pressure = Systemic Systolic Pressure—Peak Gradient Across Ventricles

Peak Gradient Across Ventricles = 4 (Peak VSD Velocity)²

Valves with similar morphology can display quite different degrees of regurgitation and functional impairment. Color Doppler interrogation requires an assessment in multiple views of all defects (Fig. 8.24, Video 8.17). Particularly in patients with a partial form of AVSD, the site where regurgitation occurs is important for surgical repair. AV valve regurgitation through the left-sided cleft is frequently directed centrally and may be part of a left ventricular to right atrial shunt. (Fig. 8.25, Video 8.18) The jet may also be directed leftwards and becomes a left ventricular to left atrial shunt. This may be related to mural leaflet hypoplasia of the left component of the AV valve [30]. Right ventricular to right atrial regurgitation may also be substantial (Fig. 8.26, Video 8.19). Often, multiple jets are present (Figs. 8.25 and 8.26, Videos 8.18 and 8.19).

Precise definition of the regurgitant jet is important for accurate interpretation of a pressure gradient in patients with partial defects. A left ventricular to right atrial regurgitant velocity will yield a high estimated gradient due to the large pressure difference between the two chambers, and if this is misinterpreted as a tricuspid regurgitant velocity, the true right ventricular pressure could mistakenly be overestimated. If, under the circumstances described here, an accurate right ventricular to right atrial jet can be identified and interrogated by spectral Doppler, a much lower velocity might be recorded.

Associated Cardiac Lesions

Additional muscular VSDs can be found in 10 % of patients with AVSDs [10]. Color Doppler flow mapping facilitates demonstration of these defects but when pulmonary hypertension is present these lesions may be missed. Decreasing the color flow Doppler scale can increase the sensitivity for low velocity color flow signals and sometimes uncover associated muscular VSDs. Tetralogy of Fallot is an important conotruncal malformation that can be seen in combination with an AVSD. This lesion is colloquially referred to as a ‘tet-canal’ defect. In this setting, the Rastelli type C defect is most commonly found (Fig. 8.27, Video 8.20). Down syndrome is present in the majority of these patients. The echocardiographic findings in this lesion are those previously mentioned for AVSDs, in addition to the features that characterize tetralogy as discussed in Chap. 12 (i.e., RVOT obstruction, aortic override). Other lesions less frequently encountered include valvar pulmonary stenosis, double outlet right ventricle, transposition of the great arteries, and truncus arteriosus. Subaortic stenosis may contribute to LVOTO and may be associated with aortic coarctation [32]. Patent ductus arteriosus is also common, particularly in patients with Down syndrome. Other chromosomal and genetic abnormalities can also be associated with AVSDs [33]. A high percentage of heterotaxy patients will have AVSDs (refer to Chap. 10). In this setting, double outlet right ventricle is a common association. The comprehensive preoperative TEE evaluation in the patient with an AVSD should also include an assessment of associated lesions as described throughout this textbook for each of the respective defects.

Postoperative TEE Evaluation

The most important goal of the postbypass TEE study is to identify significant hemodynamic abnormalities that should be addressed at the time of surgery. Important lesions requiring revision/reintervention include: residual LAVV valve regurgitation or stenosis, residual or additional VSDs, and LVOT obstruction (LVOTO) [34]. These problems, along with the need for permanent pacemaker insertion/revision, are the major indications for reoperation in patients with AVSDs, and a major cause of morbidity and mortality.

TEE has been shown to identify and estimate the severity of valvar regurgitation [35, 36].This imaging modality has been used to accurately localize mitral regurgitant lesions in adults and found to improve the assessment of patients with significant mitral regurgitation [37, 38]. Likewise, intraoperative TEE is also used to assess LAVV function after surgery in children with AVSDs (Fig. 8.28, Video 8.21) [39, 40]. Severe LAVV regurgitation was found by TEE post AVSD surgery in 5 % of patients in one study [17]. Further repair was undertaken so that no patient left the operating room with severe regurgitation. It is of interest that this study found a discrepancy in the degree of mitral regurgitation identified by intraoperative TEE versus predischarge TTE in 45 % of patients. In most cases (81 %), the degree of mitral regurgitation on the predischarge TTE was worse than that found by TEE in the operating room. This may be due to lower systemic blood pressures and higher heart rates at the time of surgery, underestimating the true severity of AV valve regurgitation. It was concluded that the grade of mitral regurgitation by intraoperative TEE does not predict the severity of regurgitation at follow-up as imaged by TTE and it was suggested that TEE findings should be interpreted in the light of the hemodynamic status. Others have also found discrepancies in the severity of mitral valve regurgitation by intraoperative TEE and subsequent TTE [41, 42]. However, these discrepancies were generally not large enough to necessitate reoperation in early to mid-term follow up, leading the authors to conclude that intraoperative TEE may be used as a tool to predict durability of surgical results and to decrease the incidence of reoperation in complete AVSDs. In other studies, an excellent correlation has been identified between intraoperative color flow assessment of LAVV regurgitation and immediate postoperative evaluation [43]. The need for reoperation was found to correlate significantly with the severity of LAVV regurgitation (r = 0.68) and intraoperative imaging was found to accurately predict the development of early postoperative heart failure and subsequent reoperation for AVSD [43].

We believe that it may not be possible to reliably assess the real degree of regurgitation because of loading conditions as well as changes in myocardial contractility, blood pressure, systemic vascular resistance, and wear and tear as the repair settles into the postoperative functional status. One of the significant errors that can be made is a too rapid report to the surgeon that the regurgitation is minimal immediately after separation from cardiopulmonary bypass. Therefore the initial post-repair TEE assessment should be followed by a later evaluation made prior to removal of the imaging probe.

The difficulties in the echocardiographic assessment of mitral valve regurgitation in children after repair of AVSD were underscored in a recent study [44]. The cohort in this report included children enrolled in a multicenter drug study (enalapril) 6 months following repair of AVSD. The evaluation of the severity of mitral regurgitation by TTE was based in the following criteria: (1) qualitative assessment; (2) measurement of vena contracta width with respect to body size; (3) calculation of vena contracta area; and (4) determination of mitral regurgitant volume and fraction. Among the quantitative parameters evaluated, the methods used in the assessment of the vena contracta were found to be minimally superior to qualitative mitral regurgitation grading. Values for regurgitant volume and fraction were frequently negative. This, in addition to poor interobserver agreement in these parameters, limited their utility.

Stenosis of the left component of the AV valve occurs most commonly after closure of the cleft in the setting of a parachute valve, and in some cases, a double-orifice LAVV. Doppler interrogation during postbypass TEE imaging in the ME 4 Ch view should recognize obstruction to left ventricular inflow so that the surgeon can relieve some of the sutures closing the cleft, or adjust an annuloplasty, if this was undertaken. This assessment can also be performed in the mid esophageal two chamber (ME 2 Ch) and ME LAX views (Fig. 8.29, Video 8.22). In this situation, the best possible balance between hemodynamically tolerable LAVV stenosis and regurgitation needs to be achieved. In rare instances, implantation of a mitral prosthesis becomes necessary; however, this is problematic in smaller patients due to the small size of the LAVV annulus.

An important aspect of the postoperative evaluation in AVSDs is interrogation for the presence of residual intracardiac shunts. Color Doppler is essential in this evaluation and when subsequent reoperation is required to address residual/recurrent hemodynamically significant shunts (Fig. 8.30, Video 8.23).

AVSDs, as previously stated, can be associated with LVOTO (Fig. 8.29, Video 8.22) [32]. Potential mechanisms of residual or new onset LVOTO include discrete subaortic fibrous stenosis, tunnel stenosis, accessory LAVV tissue and chordae, redundant LAVV tissue and apparatus, aneurysm of the mitral valve, abnormal papillary muscles, anteroseptal twist, malaligned aorta over the septum, hypertrophic muscle, and mitral valve prosthesis [45–47]. Although LVOTO usually becomes significant only in the period following surgery, the echocardiographer should investigate for LVOTO at the time of intraoperative TEE, especially in the postbypass evaluation (Fig. 8.31, Video 8.24), as any obstruction to flow may need to be addressed at time of surgery.

TEE is also of significant benefit in the recognition of other less common but important complications resulting from the repair of these defects. These problems include unusual intracardiac shunts (Fig. 8.32, Video 8.25) and the rare instance when inferior vena caval flow may be inadvertently directed into the left atrium. The use of contrast echocardiography can be particularly useful in the evaluation of these issues (Fig. 8.33, Video 8.26).

Three-Dimensional Echocardiographic Imaging

Three-dimensional (3D) TTE has been used to define the anatomy of the primum ASD in AVSDs and found to provide important information regarding the spatial orientation and alignment of the endocardial cushion region relative to the ventricles. The ability to determine this alignment and to predict the corresponding size and orientation of the AV valve has important clinical implications and would be essential for considering ASD or VSD closure (i.e., a biventricular repair), as opposed to consideration of surgical management along the single ventricle pathway [48]. This type of information, when available at the time of intraoperative TEE, would enhance the options for surgical intervention.

3D imaging has also been used to facilitate the preoperative anatomic definition of AVSDs and to predict AV valve regurgitation in children after repair by evaluating the morphology of the valve leaflets [49]. The early experience found that most often two jets of LAVV regurgitation were present in these patients after repair. One jet emanated medially from a residual ‘cleft’. The second jet originated laterally from the region of the mural leaflet. These locations were related to the relative sizes of the individual leaflets. When the origin of the jet was directed medially, this was most often associated with a smaller inferior leaflet component. When the regurgitant jet originated laterally, near the coaptation site of the superior and inferior leaflet, this was associated with a smaller mural leaflet. As 3D technology has evolved, subsequent studies have also documented the applications of this approach in regards to anatomic and functional information prior to surgical intervention in these patients [50, 51]. A recent quantitative study of real-time 3D echocardiography in children following repair of AVSD demonstrated that significant mitral valve regurgitation was associated with leaflet prolapse, larger annular area, and papillary muscle displacement in this patient group [52]. A particular strength of this technology, in addition to the diagnostic applications already mentioned, is considered its ability to define complex AV valve and LVOT abnormalities [53].

Transesophageal 3D imaging has also been applied in the assessment of these lesions. An early experience in a small number of patients reported acquisition of 3D data sets to define LAVV morphology and function in patients with AVSDs undergoing patch augmentation of the LAVV for either regurgitation or LVOTO [54]. This reconstructive 3D TEE approach, using a rotational device built into a multiplane two-dimensional (2D) TEE probe, provided clear intracardiac images as there was no interposition of ribs or lungs and the use of a high-frequency TEE transducer optimized image quality in children. Heart rate and respiratory gating were necessary, but when kept relatively constant under moderate/deep sedation, excellent data were acquired.

The availability of real-time 3D TEE represents a major advancement for the evaluation of AVSDs and has already been shown to facilitate this assessment (refer to Chap. 19 and Chap. 20) [55–57]. However, because current transducers are designed for adults, the experience in the pediatric age group has been limited to older children. Real-time 3D TEE allows for further definition of the morphological features of these defects. En face views can be reconstructed from the atrial and ventricular aspects to determine the precise anatomy of the valve leaflets (Fig. 8.34, Video 8.27). This approach enables the sites and mechanisms of valve regurgitation to be defined, and then displayed in a surgical view. In addition, during 3D imaging of these defects color flow Doppler interrogation can be adjusted so that the proximal isovelocity surface acceleration (PISA), the vena contracta (representing the regurgitant jet as it traverses the defect in the valve), and the aliased jets above can be identified in a precise relationship to the left component of the AV valve. The valve image can then be removed or retained allowing visualization of the exact appearance and size of the vena contracta. These techniques in early studies have been found to aid in the surgical planning of either primary or secondary repair of AVSDs and associated residual lesions. Similar benefits are also expected to be applicable to real-time 3D TEE.

Availability of 3D TEE using miniaturized probes in the future should allow for improved intraoperative morphologic definition of the repaired AV valve, potentially providing the surgeon with information that would allow appropriate manipulation of the valve leaflets at the time of surgery, thereby reducing the incidence of postoperative AV valve problems.

Congenital Mitral Valve Anomalies

Congenital mitral valve anomalies are rare in children but can have serious implications. These malformations include: (1) mitral stenosis, (2) parachute deformity, (3) supravalve mitral ring, (4) double-orifice mitral valve, (5) isolated cleft in the mitral valve, (6) mitral arcade, (7) straddling mitral valve, and (8) congenital valvar regurgitation.

The discussion that follows reviews the morphologic features that characterize each of these lesions and addresses relevant aspects of management, focusing on surgical approaches. A brief overview of the pathophysiology of mitral valve disease is presented. The role of TEE in the evaluation of these lesions is discussed, including goals of the preoperative examination, aspects of interest in the TEE study for each of the anomalies, assessment of the most commonly associated valvar functional abnormalities, and the postoperative interrogation. The experience to date regarding the applications of 3D imaging in congenital mitral valve anomalies is summarized.

Specific Anomalies

Morphologic Features and Management

Congenital Mitral Stenosis

Morphology—Congenital mitral stenosis was detected in 1.2 % of autopsied patients with CHD and in 0.42 % of all cardiac patients [58]. As an isolated entity this lesion occurs very rarely. Most commonly it is found within the context of mitral valve hypoplasia associated with Shone’s complex (discussed below) or in combination with other congenital pathology such as aortic coarctation [59]. Congenital mitral stenosis is usually characterized by abnormalities of all valve components and as such is defined by dysplasia of the entire mitral valve apparatus, i.e., thickened valve leaflets with rolled edges, short tendinous chords, and obliterated interchordal spaces. The lesion can also occur with papillary muscle(s) underdevelopment [12]. Although the clinical features are most notably those associated with obstruction to left ventricular inflow, valvar regurgitation also represents a manifestation of the disease.

Management Considerations—Congenital mitral stenosis is a difficult lesion to manage in infancy, accounting for significant morbidity and mortality. Interventions are necessary when obstruction is significant enough to cause symptoms. Since the pathology is complex in nature, aggressive medical management is always attempted first consisting primarily of diuretic therapy. Catheter-based procedures have been used in an effort to decrease the transvalvar mitral gradient and achieve symptomatic improvement [60]. Depending on the nature of the pathology, various surgical techniques have been applied in an effort to alleviate the obstruction [61]. These include valvotomy, commissurotomy, splitting of chordal structures and/or papillary muscles. In contrast to acquired mitral stenosis resulting from rheumatic heart disease, in most cases of congenital mitral stenosis commissurotomy is not adequate as the sole approach. Alternate strategies to valve repair include: (1) mitral valve replacement, in some cases requiring suturing the prosthesis in supra-annular position or annular enlargement; (2) placement of conduits between the left atrium and left ventricle, including replacement of the mitral valve with a pulmonary autograft (Ross II procedure); (3) single ventricle palliation, particularly in the presence of concomitant left-sided obstructive lesions; and (4) cardiac transplantation.

Parachute Mitral Valve

Morphology—A single papillary muscle in the left ventricle is the hallmark of a parachute mitral valve. Tendinous chords from the mitral valve leaflets insert onto this papillary muscle, or closely associated groups of papillary muscles, leading to the formation of the parachute deformity. A parachute mitral valve is commonly associated with other left-sided obstructive heart lesions. The constellation of lesions that include a parachute mitral valve, supravalvar mitral ring, subaortic stenosis, and coarctation of the aorta is referred to as Shone’s complex [62]. An incomplete (partial) form or variant implies the presence of fewer than these four components. A concomitant supravalvar mitral ring was recognized in 71 % of the patients with a parachute mitral valve deformity in one series, making it the most frequently detected left heart obstructive lesion in the presence of a parachute mitral valve [63]. The association of a parachute mitral valve with LVOTO is well established; however, mitral stenosis may also be associated with RVOTO, e.g. tetralogy of Fallot [64, 65].

Management Considerations—The surgical repair of a parachute mitral valve creating stenosis is challenging as full visualization of the mitral support apparatus, particularly in young patients can be extremely difficult, even more so in the case of concomitant left-sided obstructed lesions. In a case series of 12 patients with congenital mitral stenosis (9 of a parachute-type) the pathology was approached through an apical left ventriculotomy [66]. The management of this lesion may involve splitting of chordal structures and division of the single or closely spaced papillary muscle(s) enhancing the egress of left atrial blood into the left ventricle. The success rate of these types of interventions in alleviating the obstruction may be variable and likely significantly influenced by the associated lesions.

Supravalvar Mitral Ring

Morphology—A supravalvar mitral ring is a membrane lying in the funnel of the mitral valve leaflets, constricting left ventricular inflow. This anomaly almost always exists as part of a complete or partial Shone’s complex, and is rarely an isolated lesion. Therefore, a supravalvar mitral ring should be strongly suspected when typical lesions comprising the Shone’s complex are present and when the annulus of the mitral valve is hypoplastic. Conversely, identification of a supravalvar mitral ring should prompt a search for the other cardiac defects associated with Shone’s complex.

Management Considerations—Resection of a mitral valve ring is accomplished by peeling away the obstructive web from the surface of the leaflets on the left atrial aspect of the valve. In the majority of cases this is successful in relieving the inflow obstruction and allowing for the valve leaflets to move freely during diastole. At the time of surgery other lesions are addressed as indicated. This lesion, if the main cause of mitral inflow obstruction, is associated with a better prognosis as compared to other mitral valve pathology, thus identification of this particular entity is important when a patient presents with mitral stenosis.

Double-Orifice Mitral Valve

Morphology—Double-orifice mitral valve, an uncommon mitral valve lesion found in 1 % of autopsied cases of CHD, may lead to mitral stenosis, mitral regurgitation or both [67]. Various nomenclature (classic form, double parachute mitral valve) and classification schemes (complete bridge type, incomplete type, and hole type) have been proposed for this lesion based on the size and location of the two mitral valve orifices [23, 24, 67]. For practical purposes two morphological subtypes can be considered: one subtype is caused by a fibrous tissue ‘bridge’ across the left-sided orifice and is associated with AVSDs (Fig. 8.12, Video 8.7) [68]. The second subtype is caused by duplication of the mitral orifice, with each sub-orifice supported by its own tensor apparatus (Fig. 8.35) [12, 24]. These two forms cannot be easily distinguished from each other by echocardiography. Double-orifice mitral valve can also be found in the setting of a primum ASD, truncus arteriosus, left heart obstructive lesions, the CHARGE association (coloboma of the eye, heart defects, choanal atresia, growth retardation, genital and/or urinary abnormalities, ear abnormalities, and deafness), and other lesions [67, 69].

Management Considerations—In a series of 46 patients that included children and adolescents with a double-orifice mitral valve, surgical intervention specifically to address the valve was required in the minority of patients who underwent repair of associated cardiac pathologies [67]. It was reported that the long-term morbidity related to the valve pathology was low. Surgical repair of double-orifice mitral valve, most often in the setting of AVSDs, has been reasonably successful, usually by partial closure of the cleft in the anterior bridging leaflet [70–72]. In general, mitral stenosis does not occur after closure of the cleft.

Isolated Cleft of the Mitral Valve

Morphology—An isolated cleft in the anterior leaflet of the mitral valve can exist unassociated with an AVSD. In fact it has been proposed that this represents a distinct morphologic entity from the cleft of the left-sided valve of an AVSD [73]. The pathology is usually restricted to the leaflet. Findings may include leaflet dysplasia characterized by thickened and rolled edges.

Management Considerations—The most frequent indication for surgical intervention in this lesion is the presence of mitral regurgitation. The repair of an isolated mitral valve cleft usually consists of approximation of the edges of the anterior leaflet by direct suture closure. In some cases, particularly beyond childhood, more extensive valve reconstruction may be required using autologous pericardium [74]. A concomitant valve annuloplasty may be necessary.

Mitral Arcade

Morphology—An arcade represents a rare mitral valve lesion. First described in pathology specimens and subsequently by echocardiography, it consists of a bridge of fibrous tissue running along the free aspect of the anterior mitral leaflet connecting the two papillary muscles, forming an arch-like structure that obstructs the mitral orifice [75, 76]. The papillary muscle heads may be hypertrophied and closely approximated, compounding the problem at the mitral orifice [59, 77]. In these patients, mitral stenosis is the predominant presenting clinical abnormality. However, the tendinous chords are thickened and short, restricting the movement of the anterior leaflet and preventing complete closure of the mitral valve orifice, frequently also leading to mitral regurgitation. Although mitral arcade most commonly manifests in childhood, there are cases of presentation later in life due to mitral regurgitation [78, 79].

Management Considerations—Among mitral valve malformations, a mitral arcade represents a difficult lesion to successfully address surgically due to the complexity of the pathology and usually severe nature of the valve abnormalities that result in stenosis and/or regurgitation. The lack of supporting chordal structures in most cases requires extensive valve reconstruction that may include removal of fibrous tissue, creation of artificial supporting structures, splitting of papillary muscles, commissurotomy, and annuloplasty. Alternative strategies applied to the management of congenital mitral valve disease, mentioned previously, may also be required in this lesion.

Straddling Mitral Valve

Morphology—The straddling mitral valve also represents a rare defect. The term “straddling” in general implies anomalous attachments of valvar support structures (chordae, papillary muscles or both) into both ventricles, thus by definition this requires the presence of a communication at the ventricular level [80]. In this anomaly, the mitral valve straddles the septum through an anterior VSD, considered of the malalignment type. The leaflet that straddles the ventricular septum typically has an associated cleft [81], however, it is unusual for it to exhibit regurgitation. Frequently there are associated abnormal ventriculoarterial connections such as double outlet right ventricle and transposition of the great arteries [82]. Other more complex defects can be present, including those characterized by ventricular hypoplasia. In some cases, straddling valves also demonstrate ‘override’, meaning that the annulus is connected to ventricles on both sides of the interventricular septum.

Management Considerations—The straddling mitral valve frequently presents a significant surgical challenge. In most cases the options for surgical intervention involve sacrificing chordal structures, without creating a flail valve or risking the potential for mitral regurgitation, chordal transfer, or valve replacement. The single ventricle pathway may be favored in some patients.

Congenital Mitral Valve Regurgitation

Morphology—In the pediatric age group, mitral valve regurgitation is usually secondary in nature. It may result from conditions associated with left ventricular dysfunction (i.e., cardiomyopathy, myocarditis, anomalous origin of coronary artery), endocarditis, rheumatic heart disease, and systemic degenerative diseases. Additional causes include congenital pathology of the types discussed earlier in this chapter, such as AVSD, cleft mitral valve, and anomalies of the valve itself in association with other left heart malformations. This reflects the fact that mitral valve competence relies upon normal function and integrity of the entire valvular unit (annulus, leaflets, chordae tendineae, papillary muscles, adjacent left ventricular myocardium). Thus abnormalities in any of these components can result in mitral valve dysfunction.

Although rare, the entity of primary (isolated) congenital mitral regurgitation is well recognized. In many cases dysplasia and thickening of the valve leaflets is seen in association with tethering and shortening of chordal structures leading to a regurgitant valvar orifice. An element of mitral stenosis can also be found in primary regurgitant lesions.

The Carpentier nomenclature of mitral valve regurgitation, proposed in the late 1970s, continues to be used and deserves mention [83]. This classification is based on mitral leaflet motion as follows: type I has normal leaflet motion; type II has increased leaflet motion, and type III has restricted motion. This functional classification of mitral regurgitation is detailed in Table 8.1.

Table 8.1 Carpentier functional classification of mitral regurgitation

Full size table

Management Considerations—A number of techniques have been utilized in the surgical treatment of mitral regurgitation depending on the nature of the anomaly/anomalies. The objective in all cases is reconstruction and retention of native tissue if feasible. Approaches include reduction in annular size, leaflet reduction, and chordal shortening among others. Mitral valve replacement is considered a last resort, particularly in infants and young children.

Pathophysiology

It is important to consider that although the main physiologic impact of congenital anomalies that affect the mitral valve may result from isolated stenosis or regurgitation, in many cases both functional abnormalities are present. The inflow obstruction that characterizes congenital mitral stenosis, whether due primarily to valvar pathology or supporting structures, is associated with a progressive increase in left atrial pressure and elevation of pulmonary venous pressure. This results in reflex pulmonary arteriolar vasoconstriction and right ventricular hypertension. The malformations that produce mitral stenosis can have a variable clinical presentation depending upon the severity of the obstruction. In cases of mild stenosis, patients can remain free of symptoms. However, severe mitral valve stenosis is likely to be associated with poor growth and manifestations of congestive heart failure, particularly in infants. Associated obstruction of left-sided structures complicates the clinical course.

With mitral valve regurgitation, there is progressive left atrial dilation as the chamber expands to accommodate the regurgitant volume. With mild to moderate degrees of dilation, left atrial compliance is such that the chamber is able to maintain a relatively low pressure as dilation occurs. However with increasing amounts of left atrial dilation, eventually compliance decreases, leading to significant elevation of left atrial and pulmonary venous pressures, and resulting in pulmonary hypertension. The regurgitant volume, in addition, represents a load on the heart, potentially impairing myocardial performance. Although initially well compensated, long-standing mitral regurgitation can result in significant morbidity.

Transesophageal Echocardiography

Preoperative TEE Evaluation

The main objectives of the preoperative TEE examination in mitral valve anomalies are to:

Define morphology and function of the mitral valve and of its support apparatus
Obtain measurements of the mitral valve annulus, preferably from several different planes
Determine whether the primary pathology is stenosis or regurgitation (or both)
If stenosis is present, define the nature of the obstruction, and any additional level(s) of obstruction
If regurgitation is present, assess the mechanism of regurgitation
Evaluate the hemodynamic severity of stenosis/regurgitation and secondary effects on cardiac structures
Estimate right ventricular/pulmonary artery pressures
Characterize associated lesions as indicated
Assess left atrial and ventricular size, and ventricular function

Intraoperative Imaging

It is important to recognize that the mitral valve apparatus consists of multiple structures that include the leaflets, annulus, chordae papillary muscles, and the left ventricle. As such, it is imperative to carefully examine each of these components and to methodically characterize the involved pathology. TEE imaging of the left atrium, mitral valve, and left ventricle can be achieved from a combination of views that include the ME 4 Ch, ME 2 Ch, mid esophageal aortic valve long axis (ME AV LAX), ME LAX, TG Basal SAX, TG Mid SAX, TG 2 Ch, transgastric long axis (TG LAX), and deep transgastric views.

Congenital Mitral Stenosis

Most of the characteristic features of congenital mitral stenosis can be demonstrated in cross-sections displayed in the views noted above, including thick and dysplastic mitral valve leaflets, restricted funnel-shaped opening, and stiff movement of the leaflets due to short tendinous chords (Fig. 8.36). In congenital mitral stenosis the leaflets typically are more echoreflective than normal; there is often poor leaflet motion, and the valve domes during ventricular diastole (Figs. 8.37 and 8.38, Videos 8.28 and 8.29). Mitral valve leaflet thickening frequently extends onto the tendinous chords resulting in obliteration of interchordal spaces and lending the subvalvar mitral apparatus an echodense, crowded appearance.

The severity of mitral stenosis is sometimes difficult to determine in children by assessment of the transmitral gradient, because a high-pressure gradient may not be generated even in the presence of severe mitral stenosis. This is due to the frequent association of an atrial communication and/or multiple levels of left-sided obstruction (see discussion below) [59, 64]. The original description of Shone and colleagues noted that in the presence of coarctation, mitral stenosis was not readily apparent until the coarctation was resected [62].

Color flow Doppler is invaluable for morphological definition of the lesion: determining the level(s) of obstruction, assessing severity of stenosis, and defining the direction of the jets across the stenotic mitral valve (Fig. 8.37, Video 8.28) [84]. Pulsed and continuous wave Doppler can then be aligned appropriately (Fig. 8.39). Both spectral modalities are frequently applied, in particular continuous wave Doppler when velocities exceed the Nyquist limit of pulsed wave Doppler interrogation resulting in aliasing (refer to Chap. 1). As previously stated, in children with mitral valve stenosis the peak diastolic velocity is often less than 2 meters per second (m/s) because of associated atrial communications. The pressure half-time (PHT, or time for the mitral gradient to fall to half its peak value) may also be less than in the adult with acquired mitral stenosis [63, 84]. In fact, because of faster heart rates, there may be no E-F slope to measure the PHT, and the flow velocity of atrial contraction (A wave in the spectral Doppler tracing) may be higher than the velocity of early filling (E wave). Clinically significant mitral valve obstruction is suggested when peak velocities exceed 2 m/s.

Parachute Mitral Valve

The single papillary muscle can be identified at the mid esophageal level in the ME 4 Ch and ME 2 Ch views where the mitral valve leaflets appear echogenic and have restricted motion in most affected patients (Fig. 8.40). However, the anatomy is best seen in short axis views particularly those obtained by transgastric imaging (TG Mid SAX and TG 2 Ch views), where the single papillary muscle is usually detected in a posteromedial position within the left ventricle (Fig. 8.41, Video 8.30).

Supravalvar Mitral Ring

The abnormalities of the area of the ring and mitral valve are best recognized from the ME 4 Ch and ME 2 Ch views (Figs. 8.38 and 8.42, Videos 8.29 and 8.31) [85]. Alternate cross sections of the mitral valve as provided by the mid esophageal mitral valve commissural (ME Mitral; Fig. 8.43, Video 8.32) and ME LAX views (Fig. 8.44, Video 8.33) can also adequately display the pathology [86]. The supravalvar ring may be difficult to detect because it lies within the atrial surface of the valve leaflets, usually within 1–3 mm of the mitral valve annulus. The membrane of the supravalvar mitral ring may prolapse into the mitral valve orifice during diastole. During systole, it may adhere to the atrial surface of the mitral valve leaflets, but appears to dissociate slightly from them during diastole. When the left atrial appendage is visualized, it is always seen proximal to the supramitral ring, in contrast to cor triatriatum, in which the appendage is distal to the membrane (refer to Chap. 7).

In only about 10 % of patients with a supramitral ring will this pathology itself cause significant obstruction. In the remainder, associated lesions (such as a parachute mitral valve) are the cause of mitral stenosis. The lack of clinically detectable stenosis can be explained by the frequent presence of an atrial communication and/or a large, non-obstructive opening in the supravalvar mitral ring [77, 87]. Color Doppler imaging shows evidence of flow convergence toward the center of the supravalvar ring and valve (Figs. 8.44 and 8.45, Videos 8.33 and 8.34), as well as a smaller flow area through the mitral annulus than would be expected. Spectral Doppler interrogation in the absence of an interatrial communication assists in the determination of the severity of obstruction across the mitral valve (Fig. 8.46). However, when an atrial defect is present, the Doppler flow across the valve can provide less information about this lesion than for many other conditions. This is because the volume of flow through the valve is less than expected due to left-to-right atrial shunting. In addition, in the presence of associated lesions that cause mitral stenosis, the separate contribution of the supravalvar ring itself to the total inflow obstruction might be difficult, if not impossible, to quantitate.

Double-Orifice Mitral Valve

The typical echocardiographic finding in this lesion is that of two separate valvar orifices opening into the left ventricle. Although both orifices may be of equal size, more commonly they are unequal, the smaller orifice usually located in the anterolateral aspect of the left ventricle. The short axis echocardiographic plane at the level of the valve orifice, achievable by imaging in the TG Basal SAX view, equivalent to the transthoracic parasternal left ventricular short axis (Fig. 8.47, Video 8.35), is best for detecting this lesion. This anomaly may also be seen from the ME 4 Ch and ME 2 Ch views (Fig. 8.48, Video 8.36), as well as with deep transgastric imaging (Fig. 8.49) [88]. Color flow Doppler demonstrates the relative velocities through the orifices, and can depict the division of flow into two streams, each entering a separate orifice. The spectral Doppler flow characteristics are normal unless stenosis is present. It is important to recognize the fact that in double-orifice mitral valve other anomalies of the tensor apparatus can be found and should be defined [24].

Isolated Cleft of the Mitral Valve

Sweeps between a transgastric short axis view at the level of the mitral valve leaflets (TG Basal SAX) and deep transgastric views, which also display the LVOT (DTG LAX or DTG Sagittal), effectively identify the cleft pointing in the direction of the LVOT (Fig. 8.50, Video 8.37) [22, 63]. As previously indicated, this is in contrast to the cleft in AVSDs which points toward the inlet ventricular septum. There may be attachment of tendinous chords arising from the margins of the cleft to the ventricular septum, which in turn may cause LVOTO detectable by Doppler echocardiography. This is best evaluated in the ME 4 Ch, ME LAX, TG LAX, and deep transgastric views. Color flow mapping facilitates the assessment of regurgitation through the cleft.

Mitral Arcade

TEE is useful in the diagnostic evaluation of these cases [78]. Characteristically the mitral valve apparatus appears abnormal with thick and shortened chordal attachments and obliterated chordal spaces (Fig. 8.51, Video 8.38). Color Doppler imaging demonstrates flow aliasing at the level of the mitral valve inflow and in some cases multiple small jets can be observed across the valvar openings between the fused chordal structures.

Straddling Mitral Valve

The main goal in the evaluation of the straddling mitral valve is to characterize in detail the supporting structures and tension apparatus [89]. The insertion of chordal attachments may be onto a papillary muscle well within the apex of the right ventricle, to the right aspect of the interventricular septum or to the crest of the ventricular septum. Suggested views for evaluating the extent of straddling and the cleft include those where the mitral valve supporting structures are optimally seen as well as their relationships to the interventricular septum (ME 4Ch, ME LAX, TG Basal SAX). The deep transgastric views are particularly helpful in this evaluation. Sweeps that provide cross-sections of the ventricular chambers, interventricular septum, and outflow tracts from a posterior to anterior orientation are extremely valuable. This assessment is primarily done by 2D imaging (Fig. 8.52, Video 8.39). Doppler can then be applied to evaluate the mitral valve in views that provide for functional assessment as described below. Other important aspects of the anatomy should be defined, particularly the VSD, ventriculoarterial connections, and associated lesions.

Congenital Mitral Valve Regurgitation

In the evaluation of congenital mitral regurgitation suitable TEE views are those that display the left ventricular inflow as detailed previously (Fig. 8.53, Video 8.40). Specific aspects of the anatomy that should be examined include annular dimensions measured in multiple views, morphology and motion of the leaflets, and support apparatus. The exam should allow the evaluation of secondary changes of cardiac structures associated with volume overload.

Assessment of Mitral Valve Stenosis and Regurgitation

The intraoperative assessment of the severity of mitral stenosis in children relies mostly upon qualitative and semiquantitative data. In this evaluation, the main consideration is the 2D appearance of the valve leaflets and supporting structures (i.e., leaflet thickening, valve excursion in diastole, valve opening), annular dimensions, color flow pattern across the valve (i.e., presence and location of turbulence, flow convergence), and spectral Doppler assessment. Additional echocardiographic parameters evaluate the hemodynamic repercussions of the inflow obstruction, such as the magnitude of left atrial dilation and degree of pulmonary/right ventricular hypertension, as derived by the peak velocity of tricuspid or pulmonary regurgitant jet (if present) or inferred from other criteria (i.e., position of interventricular septum, right ventricular dilation/hypertrophy/function). Pulmonary venous flow patterns have also been investigated in the intraoperative setting to estimate mean left atrial pressure. As mean left atrial pressure increases, a shift in the normal pattern of predominant systolic pulmonary venous flow to one of predominant early diastolic flow has been observed [90]. However, there are limitations in this assessment that include factors such as those leading to left atrial hypertension, effects of acute versus chronic elevations, influence of associated defects, and importantly, the lack of validation of this echocardiographic parameter in the pediatric age group.

Several indices have been applied in the evaluation of mitral valve stenosis including estimation of the diastolic pressure gradient as derived from the flow-velocity curve across the valve and mitral valve area derivation (from PHT, 2D planimetry, continuity equation, and PISA) [91]. Among these indices, calculation of the transmitral mean gradient continues to be favored as it is relatively easy to obtain in the intraoperative setting. However, it is important to acknowledge a number of caveats/limitations regarding the use of this parameter: 1) an optimal angle of interrogation is critical in obtaining an accurate mitral inflow velocity, and 2) values for mean gradients are impacted by changes in cardiac output (flow and heart rate) and the presence of shunts (either intracardiac or great artery level). Related to this, as previously noted, is the fact that in the presence of multiple levels of obstruction, the severity of mitral valve inflow obstruction can be underestimated. Conversely, the presence of large left-to-right shunts (such as a large VSD) and mitral valvar regurgitation can increase the transmitral flow velocity, thereby overestimating the degree of obstruction. Mean gradients therefore should be evaluated within this context and considered as supporting evidence in severity assessment. In general, mean gradients under 5 mmHg are consistent with mild obstruction, between 5 and 10 mmHg moderate, and exceeding 10 mmHg suggest severe stenosis. The parameters to derive mitral valve area, although well validated in adult patients, in general are less applicable to children. In addition, from a practical standpoint, these measurements can be very difficult to obtain in an operating room environment.

In regards to the evaluation of mitral regurgitation, an even greater number of echocardiographic parameters have been considered [92]. In general, the assessment of disease severity relies upon: (1) morphologic features, such as the appearance of the leaflets (malcoaptation, prolapse, flail) and degree of annular dilation, (2) color and spectral Doppler parameters, and (3) degree of dilation of related cardiac structures (i.e., left atrium, left ventricle).

Doppler color flow mapping represents an essential modality in the assessment of the severity of mitral regurgitation. To a significant extent this evaluation relies upon visualization of the turbulent systolic regurgitant flow from the left ventricle into the left atrium, and qualitative assessment of the area of the regurgitant jet relative to that of the left atrium. Other parameters that should also be examined include the direction of the regurgitant jet(s), number of jets, density of regurgitant signal in the continuous wave Doppler tracing (dense signal consistent with more severe disease), presence/extent of pulmonary vein systolic flow reversal (assisted by spectral Doppler), and mitral inflow profile (higher velocities obtained with increasing severity of regurgitation in addition to a dominant E wave pattern). Although these types of assessments are performed on a routine basis, a number of important caveats should be recognized in regards to color flow mapping of regurgitant jets. The evaluation is significantly influenced by a number of technical and hemodynamic variables other than regurgitant flow and volume; equipment settings (e.g., gain) can impact image display and under/overestimate disease severity. In addition, factors such as inotropic state, volume status, vascular resistance—all of which can change in the postbypass setting—can also influence the assessment of the degree of regurgitation. Other factors such as wall impingement and fluid entrainment of the regurgitant jet, left atrial dimension, differences between left atrial and left ventricular pressures, can impact the size of the mitral regurgitant jet by color flow imaging. Another important aspect is the fact that the color Doppler image display represents velocities of moving blood elements and is not volumetric in nature as discussed in Chap. 1.

A number of echocardiographic indices provide a quantitative volumetric assessment of the regurgitant flow. These include calculations of regurgitant volume, regurgitant area, and effective regurgitant orifice area. The techniques required to derive these indices, however, have a number of limitations and are not of practical value in the intraoperative setting. The measurement of the vena contracta by color Doppler (narrowest cross-sectional area of jet width as it emerges regurgitant orifice) represents a semiquantitative parameter that has been used as a surrogate for regurgitant orifice area, a reliable index of the severity of mitral regurgitation. This measurement is helpful in the evaluation of eccentric jets but not in the presence of multiple jets (which is often the case when mitral regurgitation is seen following repair of a congenital mitral valve abnormality). Another concern is the fact that the accuracy of this method requires mapping in multiple planes to overcome limitations related to an asymmetric orifice, also presenting a challenge for immediate postbypass evaluation. In this regard, 3D imaging offers a significant advantage.

Postoperative TEE Evaluation

As discussed previously for AVSDs, an important role of postbypass TEE is to detect residual lesions that require further surgical attention [3, 93]. In congenital lesions affecting the mitral valve, an important concern is the balance between residual stenosis versus residual regurgitation. Postbypass TEE can aid in making this determination by examining the parameters previously discussed [94].

Three-Dimensional Echocardiographic Imaging

A number of publications have reported on the role of 3D echocardiography in CHD, including the assessment of congenital anomalies that affect the mitral valve [95–102]. Many of the applications of 3D imaging have already been explored for several of the malformations discussed in preceeding sections of this chapter [103–107]. The 3D TTE experience is congenital mitral valve disease is increasing as the benefits of the technology are being widely recognized. In regards to 3D TEE imaging, the reports, although limited mostly to adults due to the lack of suitable probes for children, already demonstrate clear benefits and incremental value over conventional 2D imaging [108]. The collective data thus far indicates: (1) enhanced characterization of morphologic abnormalities (spatial orientation/relationships, extent of deformities); (2) increased understanding of complex anatomic relationships; (3) better appreciation of disease severity and mechanisms of valve disease; and (4) contributions to clinical decision-making, in particular, guiding surgical management. As 3D technology continues to evolve it is anticipated that additional benefits will be derived.

Congenital Tricuspid Valve Anomalies

Isolated anomalies of a congenital nature that affect the tricuspid valve are relatively rare. In most cases, these malformations coexist in the presence of associated defects. Congenital tricuspid valve anomalies include Ebstein malformation, dysplasia, straddling, and other very unusual defects (i.e., double orifice tricuspid valve, parachute tricuspid valve). These lesions for the most part represent a spectrum of disease involving both the leaflets and subvalvar structures. The primary functional consequences of these abnormalities are tricuspid regurgitation and/or stenosis. The discussion that follows focuses on the two most common congenital tricuspid valve malformations, namely, Ebstein anomaly and tricuspid valve dysplasia. The morphologic features and management strategies are reviewed as well as relevant aspects of the pathophysiology of tricuspid valve disease. The goals of preoperative transesophageal imaging in these lesions, salient features of the exam, and postoperative evaluation are discussed. Atresia of the tricuspid valve is addressed in Chap. 10 along with other lesions that comprise the single ventricle category.

Specific Anomalies

Morphologic Features and Management

Ebstein Anomaly

Morphology—Ebstein anomaly represents a spectrum of congenital abnormalities of the tricuspid valve [109–111]. In this lesion there is displacement of the proximal attachments of the tricuspid valve leaflets, dysplasia of the leaflets, abnormalities in their distal attachments, and frequently associated tricuspid regurgitation. It is considered that the underlying right ventricular myocardium is also affected in this malformation [112].

In the more common forms of Ebstein anomaly, leftward and inferior displacement of the proximal attachments involves the septal and posterior (inferior or mural) leaflets, while the anterior (also referred as anterosuperior) leaflet is usually normally attached to the annulus, but enlarged and ‘sail-like’ [113]. The displacement of the septal and posterior leaflets is caused by partial or complete adherence to the underlying myocardium, due to lack of apoptosis-induced delamination during early valvar development. Because of the inferior displacement of these leaflets, a portion of the anatomic right ventricle becomes contiguous with the right atrium; this portion of the right ventricle is termed “atrialized” right ventricle. The remainder of the right ventricle (distal to the attachment of the displaced leaflets) is known as the “functional” right ventricle, and there can be considerable variation in size and function of this ventricular chamber. Depending upon tricuspid leaflet development and mobility, there is also a variable degree of tricuspid regurgitation, which can range from mild to very severe.

Management Considerations—The most common indications for surgical intervention in Ebstein anomaly are the presence of cyanosis and heart failure. The neonate with concomitant RVOTO may require surgical palliation by means of a systemic to pulmonary artery shunt, frequently, in the form of a modified Blalock-Taussig shunt. A number of different strategies have been applied to the critically ill neonate with intractable heart failure resulting from severe tricuspid valve regurgitation [114]. One palliative approach consists of creating functional tricuspid atresia by placing a fenestrated tricuspid valve patch in the annular position that obstructs virtually all right ventricular inflow, effectively converting the patient to a form of tricuspid valve atresia (Starnes right ventricular exclusion procedure) [115, 116]. Performed in combination with a reduction right atrioplasty, atrial septectomy, and placement of a systemic to pulmonary artery shunt, this operation assumes the eventual goal of Fontan completion. Cardiac transplantation represents an alternate option in these infants. In the older patient, valve repair/reconstruction can be attempted. Several strategies have been reported that include creation of a monocusp valve, leaflet augmentation, sliding leaflet valvuloplasties, cone repairs, plication of atrialized right ventricle, annular reduction, and a variety of other approaches with variable results [117–120]. In some cases a ‘one and a half’ ventricle management is utilized that usually combines some form of tricuspid valvuloplasty and creation of a bidirectional cavopulmonary anastomosis (Glenn shunt) [121].The goal is to effectively unload the right heart and limit the regurgitant volume. The ‘one and a half’ ventricle approach is discussed in further detail in Chap. 10.

Dysplastic Tricuspid Valve

Morphology—Isolated congenital tricuspid regurgitation may arise from abnormalities of the tricuspid architecture other than Ebstein malformation [122]. These rare causes of congenital isolated tricuspid regurgitation include tricuspid valve dysplasia, defined primarily by thickened and malformed tricuspid leaflets and short tendinous chords [123].The tricuspid leaflets may adhere to the underlying myocardium [110].The dysplastic valve in this setting typically has normal proximal attachments to the AV groove.

Management Considerations—The clinical presentation of severe forms of tricuspid valve dysplasia associated with tricuspid regurgitation mimics that of Ebstein malformation. However, the underlying myocardium in this lesion is usually normal, thus ventricular performance is less likely to be compromised, leading to a more favorable overall prognosis. The pathology may be amenable to surgical intervention [124] and include similar strategies to those applied in Ebstein anomaly, namely, valve repair, replacement, creation of tricuspid atresia and cardiac transplantation.

Pathophysiology

Related to the anatomic spectrum of tricuspid valve malformations (Ebstein anomaly and the dysplastic valve), there are also a wide range of functional abnormalities that determine the pathophysiology of these lesions [125, 126]. The main factors that influence the clinical manifestations are the severity of the tricuspid regurgitation, magnitude of the right-to-left shunt at atrial level, and the degree of right ventricular dysfunction. Mild forms of Ebstein anomaly or valvar dysplasia can present as an incidental finding and the patient may remain completely asymptomatic. At the other end of the spectrum, patients can have significant symptomatology associated with functional limitations, cyanosis, and/or arrhythmias that mandate interventions. The severely symptomatic infant represents a major challenge in terms of clinical management and overall poor prognosis.

Additional anomalies are common in these lesions. A large patent ductus in the neonate with Ebstein anomaly affects clinical management because it maintains elevated pulmonary arterial pressure and can prevent antegrade flow through the pulmonary valve. This ‘functional pulmonary atresia’ may be difficult to distinguish from true stenosis or atresia of the pulmonary valve. The presence of pulmonary regurgitation by Doppler flow or contrast echocardiography excludes true pulmonary atresia [127]. ASDs are present in almost all patients with Ebstein anomaly and can be considered part of the lesion; right-to-left shunting is generally seen through these defects. In some cases, RVOTO can be present related to the anterior leaflet of the tricuspid valve. Rhythm disturbances can occur due to (a) AV bypass tracts (Wolff-Parkinson-White syndrome) causing supraventricular tachycardia, and (b) atrial dilation leading to atrial fibrillation/flutter. A thinned right ventricular musculature may worsen right ventricular function. Other less frequent associations include VSDs, tetralogy of Fallot, and mitral valve anomalies.

Transesophageal Echocardiography

Preoperative TEE Evaluation

Prebypass TEE has had a major impact in the surgical management of patients with tricuspid valve pathology, particularly in Ebstein anomaly. An important aspect of the TEE examination is to define the morphologic features of the tricuspid valve and supporting structures in order to determine suitability for valve repair. More precise delineation of valve anatomy and function allows refinement of the surgical plan, enhancing the likelihood of a successful intervention [1]. The main objectives of the intraoperative evaluation for this or any other tricuspid valve malformation are to:

Provide anatomical details of the tricuspid valvar apparatus
Determine the presence and severity of functional abnormalities related to the malformation
Assess right and left ventricular systolic performance
Evaluate associated cardiovascular defects

Intraoperative Imaging

Comprehensive evaluation of the tricuspid valve is feasible by TEE (refer to Chap. 4) [128].The right atrium, tricuspid valve, inflow and trabecular portions of the right ventricle are adequately demonstrated in the ME 4 Ch, mid esophageal right ventricular inflow-outflow (ME RV In-Out), transgastric right ventricular inflow (TG RV In), and deep transgastric views. These views are essential in the examination of tricuspid valve disease. Additional views complement the evaluation.

Ebstein Anomaly

The characteristic anatomic features of Ebstein anomaly can be well defined by TEE. In the normal heart the septal tricuspid leaflet inserts only slightly towards the apex in comparison with the mitral valve insertion to the ventricular septum. The exaggerated degree of displacement of the septal tricuspid leaflet in Ebstein anomaly (Fig. 8.54, Video 8.41) can be determined by measuring the distances between mitral and tricuspid septal insertion and the apex (ratio between these two distances of >1.5) or the distance between the two points of insertion (>8 mm/m² of body surface area) in the ME 4 Ch view [129]. Reduced mobility of the septal leaflet may also be seen. The ME 4 Ch view also allows for definition of the AV junction and the extent of the atrialized right ventricle (Fig. 8.55, Video 8.42). The arrangement of the valve attachments forms an oblique plane that has its largest distance from the right AV groove on the septal surface of the right ventricle as best seen in the ME 4 Ch view (Figs. 8.56 and 8.57) [129].The displacement of the posterior leaflet can be demonstrated in the deep transgastric views in coronal (DTG LAX) and sagittal (DTG Sagittal) planes (Fig. 8.58) [130].The degree of displacement can be judged from the position of the AV groove. If this is not well seen, the Eustachian valve within the right atrium, which lies close to the AV groove and is often prominent in Ebstein anomaly, can be displayed by the ME 4 Ch view (with retroflexion of the TEE probe) and may aid in defining the distance of displacement of the tethered septal and posterior leaflet(s). The TG RV In, TG Basal SAX (rightward probe rotation) and ME RV In-Out views are also excellent for demonstrating tethering of the posterior leaflet to the underlying myocardium.

The anterior leaflet can be interrogated in several planes. The proximal anterior leaflet is attached to the annulus normally, as can be seen in the ME 4 Ch view. Motion of the anterior and septal leaflets can also be appreciated in this view. These features can also be displayed in the TG RV In and deep transgastric views (DTG LAX, DTG Sagittal, and modified views; Fig. 8.59). Using a combination of these cross-sections allows for better assessment of the severity of displacement and the size of the ‘atrialized’ right ventricle (Fig. 8.55, Video 8.42), while observations and measurements in just one reference plane may fail to predict the degree of severity and the need for extensive surgical intervention [131].

Planning the appropriate surgical approach is based not only on the degree of displacement of the leaflets, but also on the mode of distal attachment of the anterior leaflet [130–132]. As indicated, the valve may be tethered by a number of chordal attachments or may be attached by a band of muscle to the underlying ventricular myocardium. The former is known as a hyphenated attachment [130, 133]. The degree of this attachment can be assessed by echocardiography, although the more severe forms cannot be differentiated. Echocardiographic recognition of tethering, when severe, is important because it allows the surgeon to differentiate those cases where an annuloplasty can be performed from those where the severe tethering will not allow “liberation” of the leaflet. 3D TEE has been shown to enhance the 2D visualization of leaflet tethering [134].

Presence of linear attachments and tethering to the right ventricular free wall, especially of the large anterior leaflet, may result in obstruction between the inlet and outlet portions of the right ventricle and preclude reconstructive-types of operation [133].While linear attachments and tethering of the anterior leaflet are usually noted in the views described above, the degree of obstruction may be difficult to assess because blood flow may occur only through commissures of an immobile valve or through the interstices of the leaflets. The use of contrast echocardiography using agitated saline injected into a systemic vein has been suggested in evaluating such obstruction. Rapid filling of the left heart with contrast indicating a large right-to-left shunt may suggest severe obstruction to right ventricular inflow. Conversely, rapid appearance of contrast within the RVOT and a small amount of right-to-left shunting is more likely to represent minimal to no inflow obstruction [135].

The echocardiographic features of leaflet dysplasia in this malformation include dense echo reflection and leaflet thickening, which may be observed in almost all planes. In addition to the morphologic abnormalities of the tricuspid valve, the right atrium is typically dilated in Ebstein anomaly, in a significant number of cases to a marked extent. In the neonate this may reflect long-standing tricuspid valve regurgitation throughout fetal life.

Doppler ultrasound effectively demonstrates the tricuspid regurgitation that is present in almost all patients with this anomaly although the severity is variable, reflecting the spectrum of disease. Spectral Doppler interrogation is essential in the TEE evaluation as it provides information on diastolic inflow velocities across the tricuspid valve, facilitates the evaluation of the systolic RVOT velocities, and allows for estimation of pulmonary artery pressures. A relevant application of spectral Doppler in this setting also consists of the assessment of left ventricular outflow tract velocities to exclude obstruction resulting from septal shifting. In some cases the left ventricle can be compressed exhibiting a “pancaked” appearance (Fig. 8.60, Video 8.43).

An important aspect of the preoperative evaluation is an assessment of the functional state of the right ventricle in terms of chamber volume and systolic performance. A common finding in this lesion is a reduction in the size of the functional right ventricle, particularly in cases when there is obstruction to right ventricular output. This assessment as well as the qualitative evaluation of right ventricular function should be accomplished in multiple views, including those suggested above for the evaluation of the tricuspid valve apparatus. It is relevant to also consider surveillance of left ventricular performance, as functional impairment may co-exist resulting from altered geometry and detrimental ventricular-ventricular interactions.

Patients with congenitally corrected transposition of the great arteries (refer to Chap. 12) may display tricuspid (left-sided) valve abnormalities similar to Ebstein anomaly, thus the term “Ebstenoid” appearance (Fig. 8.61).

Tricuspid Valve Dysplasia

Intraoperative TEE plays an important role in defining the anatomy in tricuspid valve dysplasia. The same TEE views described in the evaluation of Ebstein anomaly can be utilized to assess the morphologic and functional abnormalities in this lesion. In some cases it might be difficult to distinguish clearly between primary tricuspid valve dysplasia and Ebstein malformation. This discrimination relies to a significant extent on the echocardiographic assessment of the insertion of the septal leaflet of the tricuspid valve and degree of displacement—normal in tricuspid valve dysplasia versus significant in Ebstein anomaly (Fig. 8.62, Video 8.44).

Assessment of Tricuspid Regurgitation

An important goal in tricuspid valve repair surgery is the detection and severity grading of valvar regurgitation [136]. Color Doppler interrogation, however, can be challenging due to factors such as distorted anatomy secondary to dilated cardiac chambers and unusual orientation of regurgitant jets. In Ebstein anomaly the examination should consider that the regurgitant jet frequently originates distal to the true valvar annulus, near or at the region where the displaced valvar leaflets are attached to the right ventricular endocardial surface. Thus sweeps that display the right ventricular inlet from an anterior to a posterior aspect are essential in this evaluation. This is important in both, the preoperative and postoperative evaluation.

Several parameters have been applied in the quantitative evaluation of tricuspid regurgitation by echocardiography including jet area by color Doppler, calculation of regurgitant orifice area, and measurement of the width of the vena contracta by color flow imaging [137]. These parameters, however, have not been fully validated in children or may not be applicable to congenital tricuspid valve pathology. Thus, for practical purposes in the intraoperative setting, the evaluation of tricuspid regurgitation is semi-quantitative, derived from the visual assessment that grades the degree of regurgitation from trivial to severe. Supporting criteria for severity grading may include the extent of right atrial and inferior vena cava dilation and the presence of systolic flow reversal in the vena cava and hepatic veins.

Postoperative TEE Evaluation

The focus of the postrepair TEE assessment is the determination of residual tricuspid regurgitation, exclusion of hemodynamically significant tricuspid stenosis, as well as the evaluation of myocardial function and adequacy of the repair of associated defects (Fig. 8.63). In the setting of valve replacement, a comprehensive evaluation should be performed that focuses on prosthetic valve function (refer to Chap. 16) [138, 139].

Three-Dimensional Echocardiograpic Imaging

The 3D imaging modality has been applied to the pre and postoperative evaluation of valve repair in Ebstein anomaly and allows for additional morphologic and functional evaluation than that provided by 2D imaging (refer to Chap. 19 and Chap. 20). As such, real-time 3D TEE is likely to significantly expand the contributions of intraoperative imaging in this malformation [140].

Additional Applications of TEE in Pathologies Affecting the Atrioventricular Valves

Prosthetic Mitral Valve

In adult patients, TEE has been shown to be an excellent modality for imaging prosthetic valves in the mitral position with an overall sensitivity of 96 % for detection of abnormalities [141, 142]. TEE has also been useful to investigate mitral valve prosthetic function in children (refer to Chap. 16) [143].The most common prosthetic valve abnormalities that may require TEE interrogation include abnormal motion of the leaflets, resulting in prosthetic valve stenosis or regurgitation, and infective endocarditis. Seating puffs that occur inside the sewing ring should be differentiated from paravalvar leaks which occur outside the sewing ring (Fig. 8.64). Leaflet motion analysis is feasible by TEE in most patients with a prosthetic mitral valve and this modality has a higher rate of success than TTE for single-disk and bileaflet prostheses (Fig. 8.65) [144]. TEE has also been shown to be valuable in the detection of prosthetic valve infective endocarditis (discussed in detail in Chap. 16) [145].

Mitral Valve Prolapse

Mitral valve prolapse can occur as an isolated phenomenon in an otherwise healthy individual or in those with connective tissue disorders such as Marfan syndrome [146]. As discussed in Chap. 4, the posterior leaflet of the mitral valve can be divided into three scallops namely, P1, P2 and P3. The most common site of prolapse is the middle scallop, or P2, and the adjacent segment of the anterior leaflet (referred to as A2). However, multiple scallops can be involved. The affected regions typically display a floppy appearance, thickening, and myxomatous changes. The prolapse can cause mitral regurgitation representing a potential risk factor for infectious endocarditis. TEE is indicated if imaging is not adequate by TTE to define the presence of prolapse, its mechanism, or the extent of mitral regurgitation. TEE represents an important tool to guide the repair and examine the operative results. The concerns of infectious endocarditis and chordal rupture represent additional main indications for TEE interrogation in mitral valve prolapse.

The TEE evaluation of the mitral valve in this pathology consists of imaging in multiple planes. A comprehensive examination is important because in some cases, only certain portions of the valve/tension apparatus can be affected. A systematic, methodical approach allows for accurate localization of the pathology that accounts for mitral regurgitation [37, 38]. By rotating the transducer through several planes each segment/scallop can be evaluated to define the origin of the regurgitant jet(s). In most cases the exam starts at the ME 4 Ch and navigates the entire valve annulus while moving across the ME mitral commissural, ME 2 Ch, ME LAX, and transgastric basal short axis views (Refer to Chap. 4). At each of these views the transducer can be manipulated to display anterior and posterior valvar components as well as rotated to interrogate rightward or leftward valvar regions, relative to the position of the probe. Additional long axis views of the valve at the transgastric level (TG LAX and TG 2 Ch) can offer complementary information.

Mitral prolapse represents a pathology where 3D TEE has played a significant role. In contrast to 2D TEE where evaluation of the valve requires rotation of the scanning plane in multiple views as described, 3D TEE provides a detailed structural display of the valve without the need for collecting serial 2D images and mentally reconstructing the 3D anatomy. Superimposed color information provides for localization of regurgitant jets. Importantly, the technique also allows for the valvar structures to be displayed from a surgical perspective, facilitating the repair. The benefit of 3D TEE technology in mitral valve disease continues to be documented in the literature, mostly in the adult population and in those patients suitable for imaging with currently available 3D TEE probes [147, 148].

Ruptured Tendinous Chords

Rupture of the mitral chordae is rare in children, even in those with Marfan syndrome and complications of mitral valve involvement usually only manifest towards the end of the second decade [146, 149]. In this setting, rupture of mitral chords is usually asymptomatic and only rarely causes acute hemodynamic deterioration [150, 151]. TEE in this case will demonstrate the ruptured chords appearing as mobile echogenic structures that may prolapse into the left atrium in systole and can be associated with significant mitral regurgitation. Rupture of tendinous chords can also result from bacterial endocarditis (see below). In this situation, chordal rupture can lead to acute and massive mitral regurgitation and severe hemodynamic compromise (Figs. 8.66 and 8.67).

Infectious Endocarditis

Echocardiography is a central diagnostic modality for infectious endocarditis (IE) and its potential complications and should be performed in most cases when this diagnosis is suspected and transthoracic imaging is not diagnostic (also refer to Chap. 16). In adult patients, TEE is more sensitive than TTE for detection of intracardiac vegetations and for complications such as annular abscesses, but it may be overused as a screening test. Therefore debate exists to whether TTE or TEE should be performed as the initial echocardiographic modality for IE [152, 153]. As noted throughout this textbook, children generally have better TTE windows than adults, thus smaller vegetations can be more easily detected. The decision then whether to perform TTE or TEE in children with suspected IE depends on the clinical situation [154, 155]. If the clinical suspicion for IE is low or transthoracic imaging is likely to be of good quality, then TTE is a reasonable first choice [156]. On the other hand, when transthoracic imaging produces poor images, TEE should be performed. However, before proceeding to TEE, the modified Duke criteria should be fulfilled as discussed in Chap. 16. If TTE provides negative results and the clinical suspicion for IE remains low, then other clinical entities should be considered and TEE is probably unnecessary. Also, if TTE identifies vegetations but the likelihood of complications is low, then subsequent TEE is unlikely to affect management of the patient. On the other hand, if clinical suspicion of IE or its complications is high, such as in the presence of a prosthetic valve, staphylococcal bacteremia, or new onset AV block, then a negative TTE study will not definitively exclude IE or resultant complications and TEE should be undertaken. Also, if the TTE is negative but the diagnosis of IE continues to be considered due to clinical or bacteriological suspicion, then TEE should be performed. Sometimes repeat examination after 7–10 days can be useful, as vegetations initially too small to have been visualized by TTE may have sufficiently increased in size to be detected by TEE. Extension of the infectious process or development of complications can also be detected on repeat examination. TEE should also be performed in cases where there is an initial positive TTE for IE and a high risk for cardiac complications such as perivalvular infection [154]. Multiplane TEE may be useful in identifying vegetations, which may appear as echogenic, mobile masses on the valve leaflets. The most common site in children is the mitral valve (Fig. 8.68), followed by the aortic valve. Valvular regurgitation may be present (Fig. 8.69). Surgery is indicated for complications including heart failure, recurrent embolic events, and annular abscess. In some cases the potentially aggressive nature of the microorganism might dictate the need for surgical intervention. After completion of medical and/or surgical treatment, repeat echocardiography should be undertaken to establish a baseline for follow-up that documents valvular morphology, presence of vegetations, valvular regurgitation, and ventricular function. This can be done by TTE, but as with the pretreatment study, TEE should be performed in the event of poor or difficult transthoracic imaging [154].

Summary

TEE plays an important role in the evaluation of malformations that affect the AV junction and in the assessment of congenital anomalies of the AV valves. In fact, among all the potential applications of TEE, AV valve evaluation represents one of the most important, most well recognized, and most useful. It was one of the first applications to be studied extensively following the introduction of the technology. In addition to being the subject of a significant clinical experience, AV valve evaluation has been the focus of many publications on TEE. There are clear and very compelling reasons why TEE assumes such importance in AV valve evaluation. Defects involving the AV septum and AV valves are frequently complex in nature, requiring comprehensive imaging assessment in order to develop appropriate management plans. TEE has been shown to provide detailed and highly accurate morphologic characterization of these pathologies, along with assessment of associated functional and hemodynamic abnormalities, and evaluation of coexistent cardiovascular defects. The significant intraoperative benefits of this modality have been well documented—for guiding and refining the surgical plan and, more importantly, for evaluating the adequacy of the surgical intervention. Recent experience with real-time 3D TEE imaging, although limited thus far to older children and adults, demonstrates superior benefits compared to 2D in pathology affecting the AV septum and AV valves. These include improved morphologic characterization of defects, enhanced appreciation of mechanisms of valve disease and assessment of disease severity, and better ability to guide surgical management.

Surgery for AVSDs and the AV valves continues to represent one of the most common indications for the use of the TEE in CHD. Even centers that do not routinely incorporate TEE in their standard of care during congenital heart surgery consider the assessment of these lesions a clear indication for the use of the modality. Future advances in imaging technology, particularly as these relate to the miniaturization of probes with real-time 3D capabilities, are expected to further enhance the benefits of TEE imaging in the evaluation of these defects.

Editor’s Note

In order to maintain uniformity of the TEE image/video display throughout this textbook, selected figures (Figures 8.11, 8.29, 8.36, and 8.66) and videos (Videos 8.6 and 8.22) in this chapter have been inverted vertically relative to their orientation when originally acquired. The original image/video display format submitted by the authors followed their preference to present TEE images in an anatomic orientation equivalent to that of transthoracic echocardiography.

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Author information

Authors and Affiliations

Division of Cardiology, Department of Pediatrics, The Labatt Family Heart Center, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada
Mark K. Friedberg MD
Division of Pediatric Cardiology, Department of Pediatrics, Lucile Packard Children’s Hospital, Stanford University School of Medicine, Palo Alto, CA, USA
Norman H. Silverman MD, DSc (Med), FACC, FASE, FAHA, FCP(SA)

Authors

Mark K. Friedberg MD
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Norman H. Silverman MD, DSc (Med), FACC, FASE, FAHA, FCP(SA)
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Corresponding author

Correspondence to Mark K. Friedberg MD .

Editor information

Editors and Affiliations

Childrens Hospital Los Angeles Department of Cardiology, University of Southern California Keck School of Medicine, Los Angeles, California, USA
Pierre C. Wong
Pediatric Cardiovascular Anesthesiology, Texas Children's Hospital, Houston, USA
Wanda C. Miller-Hance

Electronic Supplementary Material

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Video displays a complete atrioventricular septal defect in the mid esophageal four chamber view. The atrial (short arrow) and ventricular (long arrow) communications are seen. LA left atrium, LV left ventricle, RA right atrium, RV right ventricle (MOV 1726 kb)

Deep transgastric view demonstrating a common atrioventricular valve ‘en face’. All the components of the common atrioventricular valve are seen in this view including the superiorbridging leaflet with attachments to the crest of the septum (Rastelli type A) (MOV 545 kb)

Deep transgastric images at 55° display ‘en face’ view of common atrioventricular valve in a complete atrioventricular septal defect (MOV 3426 kb)

Video 8.4

Transthoracic parasternal short axis imagedemonstrating a cleft in left atrioventricular valve pointing toward the inlet septum in an atrioventricular septal defect (MOV 387 kb)

Transgastric basal short axis view demonstrating a cleft (arrow) in left atrioventricular valve. LV left ventricle, RV right ventricle (MOV 49255 kb)

The cleft in the left-sided component of the atrioventricular valve (arrow) is seen in this mid esophageal long axis view in a patient with an atrioventricular septal defect. In this defect the cleft points towards the septum. Ao aorta, LA left atrium, LV left ventricle, RV right ventricle (MOV 915 kb)

Deep transgastric sagittal view in a child with a complete atrioventricular septal defect and double-orifice of the left component of the atrioventricular valve. In diastole, the common atrioventricular valve orifice is seen ‘en face’ with its left (arrows) and right components. A separate valvar area of double orifice is seen over the left ventricle. LV left ventricle, PA pulmonary artery, RV right ventricle (MOV 1204 kb)

Mid esophageal four chamber view of a complete atrioventricular septal defect. Color Doppler depicts atrial shunting across two atrial communications (ostium primum and ostium secundum defects). Shunting across a small ventricular septal defect is also seen. LA left atrium, LV left ventricle, RA right atrium, RV right ventricle (MOV 473 kb)

A large secundum atrial septal defect is seen (arrow) in association with an atrioventricular septal defect. Color interrogation confirms atrial level left to right shunting. A turbulent color flow signal is identified in the left atrium corresponding to a jet of left atrioventricular valve regurgitation (not fully displayed in the video). LA left atrium, LV left ventricle, RA right atrium, RV right ventricle (MOV 2103 kb)

Video displays large ventricular component (arrow) of a complete atrioventricular septal defect. Note the right ventricular wall thickness reflecting the elevated pulmonary artery pressure that characterizes this type of lesion. LA left atrium, LV left ventricle, RA right atrium, RV right ventricle (MOV 1343 kb)

Deep transgastric long axis view depicting shunting across the ventricular component of an atrioventricular septal defect. Ao aorta, LV left ventricle, RV right ventricle (MOV 570 kb)

Mid esophageal four chamber view depicting a ventricular septal defect of the ‘atrioventricular canal-type’. In this defect separate atrioventricular valve orifices were present and the atrial communication was of the secundumtype. Several chordal attachments (arrows) are seen from the atrioventricular valves to the crest of the ventricular septum. Note the lack of normal offsetting of the atrioventricular valves. LA left atrium, LV, left ventricle, RA right atrium, RV right ventricle (MOV 1439 kb)

The ‘goose neck’ deformity of the left ventricular outflow tract that characterizes atrioventricular septal defects is shown in this deep transgastric sagittal view. Ao aorta, LA left atrium, LV left ventricle (MOV 1366 kb)

Modified mid esophageal four chamberview with anterior transducer angulation displaying chordal attachments of the left atrioventricular valve across the left ventricular outflow tract onto the interventricular septum (arrow). In some cases this can result in outflow tract obstruction. Ao aorta, LA left atrium, LV left ventricle (MOV 1723 kb)

The video displays unbalanced atrioventricular septal defects (right and left ventricular dominanttypes) as noted (MOV 3903 kb)

Mid esophageal four chamber view displays a tricuspid pouch lesion (arrow) in a patient with a partial atrioventricular septal defect. LA left atrium, LV left ventricle, RA right atrium, RV right ventricle (MOV 942 kb)

The video displays a complete atrioventricular septal defect in different transesophageal echocardiographic cross-sections. Two-dimensional imaging depicts the anatomical features of the defect. Color flow mapping demonstrates interatrial and interventricular shunting in addition to a significant regurgitant jet across the left component of the common atrioventricular valve. The characteristics of the regurgitant jet are further defined by multiplane imaging, highlighting the importance of color Doppler interrogation in multiple views (MOV 3416 kb)

Preoperative mid esophageal four chamber view displaying a partial atrioventricular septal defect. The atrial ostium primum defect is well seen and tissue tags are noted on the right ventricular aspect of the septum (no evidence of ventricular level shunting). Color Doppler interrogation demonstrates two jets originating from the left ventricle. One jet is diverted by atrial septal tissue into both atria and a second one is directed from the left ventricle into the right atrium (left ventricular to left atrial shunt) (MOV 1035 kb)

Video 8.19

The image shows preoperative color flow information obtained in a mid esophageal four chamber view using a pediatric biplane transesophageal probe in a small infant with a complete atrioventricular septal defect. Significant regurgitation is demonstrated from both the left and right atrioventricular valvar components, during systole (MOV 396 kb)

Deep transgastric long axis view in infant with Down syndrome and ‘tet-canal defect’. Note the free-floating superior bridging leaflet of the common atrioventricular valve (Rastelli type C). The characteristic aortic override in tetralogy of Fallot is well seen (MOV 4104 kb)

Postoperative transesophageal echocardiogram following repair of complete atrioventricular septal defect. Color Doppler interrogation demonstrates two small jets of left atrioventricular valve regurgitation. The jet closest to the interatrial septum represents regurgitation across a residual cleft (MOV 759 kb)

Mid esophageal long axis view displaying mitral valve stenosis resulting from cleft closure following repair of an atrioventricular septal defect. The left atrium appears dilated. Narrowing of the left ventricular outflow tract is also noted in association with multiple chordal attachments across the subaortic region onto the ventricular septum. Color flow information superimposed on the morphologic data shows a turbulent jet across the left ventricular inflow corresponding to mitral stenosis. The disturbed systolic color flow signal across the left ventricular outflow tract also confirms the subaortic obstruction. A small jet of aortic regurgitation is noted. The coronary sinus appears mildly dilated (MOV 1292 kb)

Preoperative transesophageal echocardiogram inan infant requiring reoperation to address a residual inlet ventricular septal defect as well as significant regurgitation across a large left atrioventricular valve cleft related to suture dehiscence Both lesions are well characterized by color flow imaging in the mid esophageal four chamber view (MOV 3455 kb)

Deep transgastric long axis view obtained following repair of an atrioventricular septal defect. The image displays interrogation of the left ventricular outflow tract using a combination of Doppler modalities (color flow mapping and spectral Doppler). No evidence of obstruction was demonstrated. Note the favorable angle for pulsedwave Doppler interrogation of the outflow tract in this view. Ao aorta, LV left ventricle, RV right ventricle (MOV 2884 kb)

Postbypass transesophageal echocardiogram obtained in the mid esophageal four chamber view demonstrates flow by color Doppler from the left atrium (LA) into the right ventricle (RV; blue jet). This communication, representing a left to right shunt, was inadvertently created during repair of the defect. The echocardiographic findings led to revision of the repair. LV left ventricle, RA right atrium (MOV 2179 kb)

The initial portion of the video displays a mid esophageal four chamber view obtained immediately after separation from bypass following repair of a complete atrioventricular septal defect. Both atrial and ventricular septal patches are well seen. A contrast study was performed to evaluate a small color Doppler signal suggestive of residual ventricular level shunting (not shown). Agitated saline injected through a femoral venous catheter demonstrated opacification of the right atrium with unexpected almost immediate appearance of contrast in the superior aspect of the left atrium. The atrial septal defect patch was well outlined in the contrast injection and the shunting did not appear to be related to a residual leak at this level. The findings were thought to be consistent with mistaken partial incorporation of inferior vena cava flow into the left atrium (right to left shunt). This was confirmed upon return to bypass and after surgical revision (postbypass #2) the same contrast injection demonstrated an expected normal flow pattern and no residual shunts. LA left atrium, LV left ventricle, RA right atrium, RV right ventricle (MOV 3058 kb)

Three-dimensional image obtained by transesophageal echocardiography in an older child displaying ‘en face’ view of a complete atrioventricular septal defect (Video provided by David A. Roberson, M.D.) (MOV 1049 kb)

Mid esophageal four chamber view displaying an abnormal mitral valve. The mitral valve exhibits grossly abnormal leaflets with reduced diastolic excursion. Small ridges on the leaflets could be construed as a supravalvar mitral ring. Color Doppler imaging demonstrates a turbulent color jet across the mitral valve. The degree of flow velocity acceleration is significant, reaching the left ventricular apex before it turns round, while maintaining its dimensions until distorted by the apical wall. This finding indicates the significant severity of the obstruction. LA left atrium, LV left ventricle, RA right atrium, RV right ventricle (MOV 2152 kb)

Video 8.29

Video displays a mid esophageal four chamber view in a child with a mitral stenosis. The distorted funnel-shaped mitral valve inflow is seen. A tiny ridge at the posterior annulus is suggestive of a supravalvar mitral ring. The left atrium appears substantially enlarged (MOV 533 kb)

Transgastric imaging in the mid left ventricular short axis and two chamber views demonstrates a single posteromedial papillary muscle in a child with a parachute mitral valve deformity (MOV 2195 kb)

Transesophageal echocardiogram depicts a supravalvar mitral ring (arrow). The pathology is well seen in orthogonal views that display the mitral inflow (mid esophageal four chamber and two chamber views). Color Doppler demonstrates flow acceleration at the level of the mitral valve annulus and a small jet of mitral regurgitation. LA left atrium, LV left ventricle, RA right atrium, RV right ventricle (MOV 4135 kb)

The images display a supravalvar mitral ring as viewed from the mid esophageal mitral valve commissural view obtained at 60°^. The supravalvar ridges (arrows) that characterize this lesion are shown (arrows). Note the dilated left atrium (LA). LV left ventricle (Video provided by Louis I. Bezold, M.D.) (MOV 1706 kb)

Mid esophageal long axis view recorded from the same infant depicted in Video 8.32 demonstrate a supravalvar ring and reduced diastolic excursion of the mitral valve leaflets. Aliasing of the color flow signal at the mitral inflow confirms the obstruction. Associated lesions included aortic valve stenosis, a subaortic ridge and a perimembranous ventricular septal defect. Ao aorta, LA left atrium, LV left ventricle, RV right ventricle (Video provided by Louis I. Bezold, M.D.) (MOV 1841 kb)

Mid esophageal four chamber view displaying flow convergence between the left atrium and left ventricle due to a supravalvar mitral ring. Additionally, two jets of mitral inflow in diastole are seen corresponding to two areas of stenosis in this abnormal mitral valve. A regurgitant mitral jet is also evident. A small amount of aortic regurgitation is seen (MOV 2027 kb)

Transthoracic left ventricular short axis image depicting a double-orifice mitral valve (MOV 7001 kb)

Mid esophageal two chamber view depicting a double-orifice mitral valve. Two-dimensional imaging shows two distinct valvar orifices during diastole. Color flow appears more prominent across the more posterior valvar opening, which also displays a small jet of regurgitation. No evidence of obstruction is detected across the valve by color Doppler (confirmed by pulsed wave Doppler interrogation in the mid esophageal four chamber view) (MOV 6204 kb)

Transgastric basal short axis view displays the mitral valve in short axis. The cleft (arrow) is associated with mitral regurgitation as depicted by color Doppler imaging. LV, left ventricle; RV, right ventricle (MOV 4417 kb)

Multiplane imaging of the mitral valve demonstrating restricted diastolic valvar motion and marked thickening leaflets and support apparatus. The leaflets appear to insert directly into bulky subvalvar structures without definitive chordae, suggesting the presence of a mitral arcade (confirmed at surgery). Color Doppler demonstrates aliased flow across through an eccentric opening and a mitral regurgitant jet (MOV 6534 kb)

Transesophageal echocardiogram depicting a straddling mitral valve in a child with double outlet right ventricle. The sweep starts at the mid esophageal four chamber view. As the transducer is anteflexed from a posterior position a ventricular septal defect comes into view. At this level, chordal attachments from the mitral valve are seen to straddle the ventricular septum and insert on the right ventricular aspect near the crest of the ventricular septum. The abnormal, side-by-side spatial orientation of the great arteries is depicted. A secundum atrial septal defect is seen. The deep transgastric long axis view demonstrates abnormal mitral valve chordal structures along the pathway from the left ventricle to adjacent great artery (aortic root) (MOV 187567 kb)

Multiplane examination in the mid esophageal and transgastric views in infant with congenital mitral regurgitation. Two-dimensional imaging demonstrates the dysplastic and thickened valve leaflets with rolled edges that coapt poorly. A broad mitral regurgitant jet is seen coursing along the posterolateral aspect of the left atrium. Severe left atrial dilation is seen with shifting of the interatrial septum in the left to right direction consistent with left atrial hypertension (MOV 214452 kb)

The characteristic features of Ebstein anomaly are displayed in this mid esophageal four chamber view including: apical septal leaflet displacement, redundancy of the anterior leaflet, and atrialization of the right ventricle. The anterior, ‘sail-like’ leaflet prolapses mildly into the right atrium. Although the left ventricle is not well seen, the right ventricle appears to be the dominant ventricular chamber in this patient (MOV 7350 kb)

Mid esophageal four chamber view of severe form of Ebstein anomaly displaying adherence of the tricuspid septal leaflet to the underlying myocardium and tethering of chordal structures. The marked redundancy of the anterior leaflet is seen. The valvar coaptation point is displaced well into the apex of the right ventricle. The deep transgastric sagittal view depicts the degree of atrialization of the right ventricle. Note the small size of the ‘true’ or ‘functional’ right ventricle. aRV atrialized right ventricle, LA left atrium, LV left ventricle, RA right atrium, RV right ventricle (MOV 1079 kb)

Mid esophageal four chamber view demonstrating bulging of the interventricular septum towards the left ventricle (septal shift), resulting in narrowing of the left ventricular outflow tract (LVOT) and a “pancaked” appearance of the left ventricle (LV). Ao aorta, LA left atrium, LV left ventricle, RV right ventricle (MOV 859 kb)

Mid esophageal four chamber view displaying an abnormal tricuspid valve (thickened and dysplastic leaflets) with associated severe regurgitation. The images show an exaggerated degree of normal offset of the atrioventricular valves onto the septum suggesting a more likely diagnosis of Ebstein anomaly over that of tricuspid valvar dysplasia, where normally hinged leaflets are present. LA left atrium, LV left ventricle, RA right atrium, RV right ventricle (MOV 5206 kb)

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Friedberg, M.K., Silverman, N.H. (2014). Atrioventricular Septal Defects and Atrioventricular Valve Anomalies. In: Wong, P., Miller-Hance, W. (eds) Transesophageal Echocardiography for Congenital Heart Disease. Springer, London. https://doi.org/10.1007/978-1-84800-064-3_8

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DOI: https://doi.org/10.1007/978-1-84800-064-3_8
Published: 26 August 2013
Publisher Name: Springer, London
Print ISBN: 978-1-84800-061-2
Online ISBN: 978-1-84800-064-3
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Atrioventricular Septal Defects and Atrioventricular Valve Anomalies

Abstract

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Atrioventricular Septal Defects

Atrioventricular Septal Defects

Echocardiographic assessment of left to right shunts: atrial septal defect, ventricular septal defect, atrioventricular septal defect, patent arterial duct

Keywords

Introduction

Atrioventricular Septal Defects

Morphology

Pathophysiology

Management Considerations

Transesophageal Echocardiography

Preoperative TEE Evaluation

Intraoperative Imaging

Two-Dimensional Imaging of Complete Defects

The Atrioventricular Septum and Common Atrioventricular Valve

The Interatrial Communication

The Ventricular Component of the Defect

Commitment of the Atrioventricular Junction to the Ventricles

Two-Dimensional Imaging of Incomplete (Partial) Defects

Doppler Evaluation of Defects

Associated Cardiac Lesions

Postoperative TEE Evaluation

Three-Dimensional Echocardiographic Imaging

Congenital Mitral Valve Anomalies

Specific Anomalies

Morphologic Features and Management

Congenital Mitral Stenosis

Parachute Mitral Valve

Supravalvar Mitral Ring

Double-Orifice Mitral Valve

Isolated Cleft of the Mitral Valve

Mitral Arcade

Straddling Mitral Valve

Congenital Mitral Valve Regurgitation

Pathophysiology

Transesophageal Echocardiography

Preoperative TEE Evaluation

Intraoperative Imaging

Congenital Mitral Stenosis

Parachute Mitral Valve

Supravalvar Mitral Ring

Double-Orifice Mitral Valve

Isolated Cleft of the Mitral Valve

Mitral Arcade

Straddling Mitral Valve

Congenital Mitral Valve Regurgitation

Assessment of Mitral Valve Stenosis and Regurgitation

Postoperative TEE Evaluation

Three-Dimensional Echocardiographic Imaging

Congenital Tricuspid Valve Anomalies

Specific Anomalies

Morphologic Features and Management

Ebstein Anomaly

Dysplastic Tricuspid Valve

Pathophysiology

Transesophageal Echocardiography

Preoperative TEE Evaluation

Intraoperative Imaging

Ebstein Anomaly

Tricuspid Valve Dysplasia

Assessment of Tricuspid Regurgitation

Postoperative TEE Evaluation

Three-Dimensional Echocardiograpic Imaging

Additional Applications of TEE in Pathologies Affecting the Atrioventricular Valves

Prosthetic Mitral Valve

Mitral Valve Prolapse

Ruptured Tendinous Chords

Infectious Endocarditis

Summary

Editor’s Note

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Electronic Supplementary Material

Video 8.4