Introduction

Congenital heart disease (CHD) is seen in approximately 1% of the pediatric population [1]. The prevalence of CHD reportedly varies geographically and Asia has the highest prevalence, with 9.3 cases reported for every 1000 live births [2]. About 40% of children who require cardiac surgery by 1 year old are said to undergo non-cardiac surgery by 5 years old [3, 4]. The frequency of pediatric gastrointestinal disorders combined with CHD has been reported to be 16.5–28.5% [5,6,7] in the relevant literature.

It has been 10 years since the Department of Pediatric Cardiovascular Surgery was established at our institution, allowing us to consolidate CHD cases requiring surgical intervention. With the establishment of this department, cases that previously required maternal or neonatal transport to distant facilities can now be treated entirely within our local area. We therefore reviewed our decade experience from the perspective of the prognosis and report how we pediatric surgeons should manage infants with CHD who require surgery for representative neonatal surgical diseases.

Materials and methods

Study design and data collection

A retrospective chart review was performed on congenital neonatal surgical cases with and without CHD treated from January 1, 2011 to December 31, 2020. Low-birth-weight infants (LBWIs), very-low-birth-weight infants (VLBWIs), and extremely low-birth-weight infants (ELBWIs) with congenital neonatal surgical disease complicated with patent ductus arteriosus (PDA) alone were excluded from this study. In addition, LBWIs, VLBWIs, and ELBWIs with necrotizing enterocolitis, focal intestinal perforation, and meconium related ileus, which are also associated with some acquired factors, were excluded from this study. We focused on the relationship between congenital neonatal surgical disease and CHD and the associated mortality rate in this study.

Statistical analyses

The qualitative data were analyzed using a chi-square test with Yates' correction, and the quantitative data were compared using Student's t-test. Statistical analyses were performed using the IBM SPSS Statistics software program, version 27 (IBM, Tokyo, Japan), for Windows. P values of < 0.05 were considered to indicate statistical significance.

Ethical approval

This study was performed in accordance with the Ethical Guidelines for Medical and Health Research Involving Human Subjects by the Ministry of Health, Labor and Welfare of Japan in 2014 and in compliance with the 1964 Declaration of Helsinki (revised in 2013). Patient data were collected with blinding of personal information and registered using consecutive patient numbers. This study was also approved by the local ethics committee of our institution (27–119).

Results

Differences in patient background characteristics by the presence of CHD

There were 416 neonatal surgical cases during the 10-year period, 68 cases with neonatal asphyxia who required extracorporeal membrane oxygenation catheter insertion for cerebral hypothermia, and 73 cases who met the aforementioned criteria were excluded. Remaining 275 cases were included in the present study. Thirty-six patients (13.1%) had CHD. Differences in patient background characteristics by the presence of CHD are shown in Table 1. There were no marked differences in the proportion of gender and gestational age between the groups with and without CHD. Infants with CHD tended to be lighter in weight (2355.5 g vs. 2716 g; p < 0.001) and had a higher delivery rate with Caesarean Sect. (63.9% vs. 42.3%; p = 0.024). The total number of deaths was 11. While the mortality rate in patients without CHD was 1.3% (3/239), that of patients with CHD was 22.2% (8/36), as shown in Table 1. The mortality rate was significantly higher in patients with CHD than in those without it (χ2 = 30.6, p = 3.23 E–8). The relative risk for death along with CHD was estimated to be 17.1

Table 1 Differences in patient background characteristics according to the presence or absence of CHD
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Frequency of CHD in congenital neonatal surgical disease

The frequency of CHD in congenital neonatal surgical disease is summarized in Table 2. Esophageal atresia (EA) showed the highest complication rate with CHD (43.8%), followed by duodenal atresia (DA; 38.5%), intermediate-high anorectal malformation (ARM; 18.8%), low ARM (15.4%), omphalocele (15.4%), and congenital diaphragmatic hernia (CDH; 8.0%). The most common CHD was ventricular septal defect (VSD), followed by atrial septal defect (ASD), tetralogy of Fallot (TOF), total anomalous pulmonary venous return (TAPVR), double-outlet right ventricle (DORV), coarctation of aorta (CoA), pulmonary atresia (PA), and single ventricle (SV), as shown in Table 2.

Table 2 Frequency of CHD (including duplicate cases)
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Details of fatal cases

Among the eight fatal cases with CHD, four (case 1–4) died when their general condition was stable after surgery for congenital non-cardiac surgical disease. Notably, all had cyanotic complex heart disease, such as TAPVR, DORV, and TOF, which brought sudden hemodynamic changes in patients and which was associated with death. Two (case 1, 2) of the four patients had undergone cardiac surgical intervention by cardiovascular surgeons. Before cardiac arrest, there was a marked drop in the percutaneous oxygen saturation (SpO2) in all cases. In the remaining four, the respiratory failure was thought to be the direct cause of death. Three (case 5, 6, 7) of these four cases had a background of congenital airway anomalies. One patient died of sudden unexplained ventilator failure during esophageal reconstruction for EA. A summary of eight cases concerning mortality with CHD is shown in Table 3.

Table 3 Details concerning mortality with CHD
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There were three deaths among the cases without CHD: a patient with bilateral kidney anomalies (right anaplastic kidney + left atrophic multi cystic kidney) and ARM without fistula, who died of renal failure with difficulty in continuing peritoneal dialysis; a patient with bilateral diaphragmatic hernia, who died due to septic shock; and a patient with septic shock after surgery for strangulated ileus due to the mesodiverticular band in Meckel's diverticulum.

Discussion

The present study revealed the following findings: (1) the mortality rate of 36 children with congenital neonatal surgical disease complicated by CHD was considerably higher than that of 239 children without CHD (8/36, 22.2% vs. 3/239, 1.3%, p < 0.0001); (2) the birth weight of neonates with congenital surgical disease complicated with CHD was significantly lower than that of uncomplicated neonates; (3) patients with cyanotic complex CHD, such as TAPVR, DORV, and TOF, showed rapid hemodynamic changes, which were associated with patient mortality.

The prognosis for CHD is reported to be about 85% based on a 5-year survival assessment, ranging from 14% with complex CHD, such as hypoplastic left heart, to 96% with simple CHD, such as VSD [8]. In general, the mortality rate for pediatric cardiovascular surgery are approximately 3–4% [9, 10]. However, when CHD is associated with congenital neonatal surgical disease, the mortality rate is reported to increase nearly three to fourfold [10,11,12,13]. The mortality rate of our 36 infants, 22.2%, was slightly higher in comparison to these former reports, and was 17 times higher than that of infants without CHD. Given the high mortality rate, the presence of CHD is an important issue to be considered in the treatment of neonatal surgical diseases.

In general, the survival of infants with CHD is known to be influenced by gestational age at birth (especially < 32 weeks) and birth weight (especially smaller than − 2 standard deviations [SD] for gestational age) [14]. We found no difference in gestational age between patients with and without CHD in our study (p = 0.0712), but birth weight was smaller in patients with CHD than in those without it (p = 0.0004). On comparing surviving and deceased cases with CHD, the mean gestational age was younger in fatal cases (37.0 weeks vs. 35.8 weeks, p = 0.1954), and the mean birth weight was significantly lower in fatal cases (2468.3 g vs. 1960.5 g, p = 0.0121). Of the eight deaths in our study, two (Table 3, case 5 and 6) were born before 32 weeks of gestation, and two (Table 3, case 3 and 8) were born with weights smaller than − 2 SD for their gestational age. These seem to be important factors to keep in mind.

On reviewing the causes of death, the association of CHD was implicated in four cases (Table 3, case 1–4). All four patients had cyanotic complex cardiac anomalies and died once their condition had stabilized after surgery for congenital neonatal surgical diseases. Two patients died despite intervention by pediatric cardiovascular surgeons to improve their circulation dynamics. The adverse events are considered to be possible complications after cardiovascular surgery for CHD. There was no time to perform rescue intervention for the sudden changes in hemodynamics in the remaining two cases. It was difficult to determine retrospectively whether or not the deaths in these two cases were avoidable.

Patients with cyanotic CHD are known to be capable of maintaining an adequate cardiac output and oxygen delivery even in situations where pulmonary blood flow is restricted, unless the arterial oxygen saturation is not too low and adequate hemoglobin levels are maintained [15]. However, when metabolic acidosis or lactic acidosis are observed, the oxygen delivery may already be recognized to be inadequate [16], and it is easily assumed that intervention may be difficult because the patient’s general condition deteriorates rapidly. According to a report that examined the relationship between desaturation and adverse events during invasive procedures in children with CHD, when a decrease in saturation of more than 30% with pulse oximetry is shown, it is 4.03 times more likely to cause adverse hemodynamic events in patients with cyanotic heart disease [17]. Maintaining an adequate oxygen saturation may help to avoid such adverse changes in hemodynamics in patients with cyanotic heart disease. Pediatric surgeons should take care to observe the oxygen saturation over time and maintain adequate hemoglobin levels, and by sharing this information promptly with pediatric cardiologists and pediatric cardiovascular surgeons, patient mortality may decrease and become closer to that of patients with CHD alone.

The limitation of this study is the restricted number of cases. The proportion of cases with cyanotic complex CHD was 50.0% (18/36) in our study. This fact may explain the higher mortality of patients with CHD compared to that of the relevant literature [10,11,12,13]. Although it has been 10 years since the Department of Pediatric Cardiovascular Surgery was established at our institution, there is still room for improvement in the perioperative management of patients represent neonatal surgical diseases with CHD.

Conclusions

Considering its high mortality, the presence of CHD is an important issue to be considered in the treatment of congenital neonatal surgical diseases. Particularly in the treatment of patients with cyanotic complex CHD, changes in the circulatory dynamics, not only in the perioperative period, but also in a remote period after the initial operation for congenital diseases, have to be kept in mind. Pediatric surgeons should be aware of the importance of a decrease in oxygen saturation which may result in adverse hemodynamic events in children with CHD. At the same time, prompt sharing of the information with pediatric cardiologists, cardiovascular surgeons, intensivists, and neonatologists should be emphasized in a daily management.