Introduction

Standard color Doppler assessment during intraoperative transesophageal echocardiography may sometimes be insufficient due to blood flow velocities.

Case presentation

A 22-year-old male with right heart enlargement on transthoracic echocardiography was diagnosed with a secundum atrial septum defect (ASD) on transesophageal echocardiography (TEE). Cardiac catheterization revealed left to right shunt with a Qp/Qs ratio of 2.9. Due to the large size of the ASD (35 × 29 mm), the ASD closure by minimally invasive cardiac surgery (MICS) was performed instead of the transcatheter closure. After ASD closure, color Doppler imaging during intraoperative TEE revealed that the blood flow via the superior vena cava (SVC) was entering not only the left atrium but also the right atrium (Fig. 1, left panel).

Fig. 1
figure 1

Left panel: post-ASD patch closure. The arrow appeared to show bifurcated blood flow from SVC to the right and left atrium in color Doppler imaging. But under only color Doppler evaluation, we cannot confident that its flow is from SVC. Right panel: contrast echocardiography revealed bubbles (arrow) in the right and left atrium

Full size image

Therefore, for intraoperative diagnosis, bubbles were injected into the peripheral vein of the right upper extremity as a contrast echocardiography. Subsequently, bubbles appearing simultaneously in the left and right atrium suggest that the patch suture of the superior side extended to the SVC (Fig. 1, right panel). Afterward, a median sternotomy was performed for the subsequent repair.

Discussion

Contrast echocardiography has been reported as a useful method for a diagnostic purpose [1]. Compared to median sternotomy, it is often challenging to secure a clear whole view in MICS. In our case, bifurcated blood flow from the SVC on color Doppler imaging would indeed suggest an inappropriate suture extending into the SVC which was confirmed by contrast echocardiography.

Some case reports demonstrated the usefulness of contrast echocardiography in intraoperative TEE. Maddali et al. [2] reported a case where residual ventricular septal defect (VSD), undetectable by color Doppler, was identified using contrast echocardiography. Similarly, Jeans et al. [3] reported a case where closure insufficiency in left atrial appendage closure surgery was revealed. Even after reducing the Nyquist limit, the assessment by color Doppler imaging remained insufficient in both cases. Bommer et al. [1] reported an incidence rate of air embolism with contrast echocardiography at 0.062%. Furthermore, another report indicated that only 2–3% of patients with grade 3 or higher shunts experience paresthesia and migraine, while those with grade 3 or lower shunts have no adverse events [4]. However, the safety of contrast echocardiography under using the cardiopulmonary bypass is unclear. For intraoperative diagnosis, it is important to consider the advantages and disadvantages of techniques such as contrast echocardiography and color Doppler imaging in an optimal manner.