Heterotaxy and AVC: the surgical challenge of complex venous returns

Anatomical labyrinth and imaging limitations: the challenge of situs ambiguus

Heterotaxy syndrome (situs ambiguus) often presents the cardiac surgeon with a major technical challenge, where the heterogeneity of systemic and pulmonary venous return anomalies defies standard diagnostic protocols. This report details the case of a 2-year-old child (10.5 kg) presenting with complex congenital heart disease combining a common atrioventricular canal, an interruption of the inferior vena cava with hepatic drainage into the left atrium, and levocardia. The central problem of this study lies in the blatant discrepancy between the multiple initial echocardiographies and the cardiac CT angiography, which failed to identify the entire aberrant vascular network before opening the thorax.

The objective of this presentation is to report a rare combination of systemic and pulmonary venous anomalies and to illustrate the current diagnostic limitations of non-invasive imaging in heterotaxy syndromes. The authors support the hypothesis that, despite the increasing accuracy of modern imaging, direct intraoperative assessment remains the decisive step for correcting structures unidentified preoperatively, such as a left superior vena cava draining into the left atrium or partial anomalous pulmonary venous returns (PAPVR). This case highlights the need for immediate strategic flexibility during the surgical management of these complex patients.

Case report methodology

This publication documents the surgical management of a unique pediatric patient, within the framework of a clinical case report (case report). The study details the diagnostic and therapeutic journey of a 2-year-old child, weighing 10.5 kg, presenting with complex congenital heart disease associated with situs ambiguus.

The evaluation and intervention protocol followed these steps:

• Multidimensional diagnostic evaluation: Performance of multiple transthoracic echocardiographies supplemented by cardiac computed tomography (CT) to map the systemic and pulmonary venous anatomy.
• Identification of anomalies: Comparative analysis between preoperative imaging data (initially suggesting an atrioventricular canal and abnormal hepatic drainage) and intraoperative findings.
• Corrective surgical procedure:
  • Mitral (cleft correction) and tricuspid valve repair.
  • Tunneling (baffling) of the left superior vena cava and hepatic venous drainage to the right atrium using bovine pericardium patches.
  • Closure of interatrial communications (or common atrium).
  • Removal of pulmonary artery banding and enlargement of the main pulmonary artery using bovine pericardium.
• Postoperative follow-up: Intensive monitoring of complications (arrhythmias, low cardiac output, renal function via peritoneal dialysis) over a 10-day hospitalization period before returning home.

Clinical Results and Observations

The patient, a 2-year-old child weighing 10.5 kg, presented with a complex clinical picture of congenital heart disease associated with situs ambiguus. The analysis of the results highlights a significant discrepancy between non-invasive explorations and intraoperative findings, underlining the diagnostic challenges of heterotaxy.

Comparison of diagnostic data

The following table summarizes the discrepancies observed between preoperative imaging (echocardiography and cardiac CT scan) and the anatomical reality found during surgery:

Intraoperative observations and surgical correction

Surgical exploration revealed a more complex anatomy than expected, notably the presence of a left SVC draining into the LA, initially not visualized on the CT scan. The surgical strategy had to be adapted in real time to include:

• The creation of tunnels (baffling) using bovine pericardium to redirect the left SVC and hepatic drainage towards the right atrium.
• The closure of atrial septal defects.
• Mitral valve repair (cleft correction) and tricuspid valve repair.
• The removal of the previously placed pulmonary artery cerclage (PA band), with augmentation of the main pulmonary artery using bovine pericardium.

Postoperative follow-up and evolution

Although the procedure achieved complete anatomical correction, the immediate postoperative period was marked by clinical instability:

• Rhythm disorders: Arrhythmias requiring temporary cardiac pacing.
• Hemodynamics: Low Cardiac Output Syndrome (LCOS) managed by inotropic support.
• Renal function: Necessity of temporary peritoneal dialysis to compensate for postoperative acute renal failure.

Despite these complications, a complete recovery was observed. The patient was able to be discharged from the hospital 10 days after the procedure, with a return home and a resolution of the organ failures.

Analysis of anatomical complexity and imaging limitations

This clinical case highlights the frequent discrepancy between preoperative imaging assessment and intraoperative anatomical reality in heterotaxy syndrome. While the cardiac CT scan correctly identified the situs ambiguus and abnormal hepatic drainage, it failed to precisely characterize the left SVC draining into the left atrium as well as the complexity of the partial pulmonary venous return. This observation underlines the intrinsic limitations of echocardiography and CT imaging when faced with the heterogeneity of veno-atrial connections in these patients.

The success of the repair, despite a more complex anatomy than expected, demonstrates that a flexible surgical strategy is essential. The postoperative complications encountered — arrhythmias, low cardiac output syndrome, and the use of peritoneal dialysis — are representative of the intensive management required for a 10.5 kg child presenting with such anomalies. Nevertheless, the complete recovery at 10 days confirms the viability of venous reconstructions by baffling to restore consistent physiology.

In comparison with literature data on heterotaxy syndromes, this case perfectly illustrates the rule of exception: each patient presents a unique anatomical signature. For the clinician, the lesson is clear: imaging provides a map, but only intraoperative examination allows for definitive navigation through these intertwined systemic and pulmonary venous malformations.

In practical terms, for the practitioner:

• Beware of preoperative imaging: In heterotaxy syndromes, ultrasound and CT scans may underestimate the complexity of venous returns; intraoperative exploration remains the decisional "gold standard".
• Anticipating rare systemic anomalies: Be prepared to surgically manage direct hepatic drainage into the left atrium or a persistent left superior vena cava, even in the absence of clear radiological signs.
• Increased post-operative vigilance: Despite a successful anatomical repair, the risk of arrhythmias and low cardiac output syndrome remains high during the first 48 hours, often requiring invasive support (pacing, dialysis).

Technical lexicon of the study

Situs ambiguus: Abnormal and random positioning of thoracic and abdominal organs, corresponding neither to situs solitus (normal) nor to situs inversus (mirror), often a marker of complex cardiopathies.

Heterotaxy: Visceral malposition syndrome resulting from a failure to establish normal right-left sidedness during embryonic development, frequently associated with venous return anomalies.

Interrupted inferior vena cava: Congenital anomaly characterized by the absence of the hepatic segment of the IVC, resulting in a modification of the lower systemic venous drainage, often towards the azygos vein or directly towards the atrium.

Levocardia: Condition where the heart is located in the left hemithorax. In the context of situs ambiguus, this position can coexist with an anarchic arrangement of the other organs.

Abnormal hepatic venous drainage: Direct connection of the hepatic veins to a non-physiological cardiac cavity (the left atrium in this clinical case) instead of joining the terminal segment of the inferior vena cava.

Partial anomalous pulmonary venous return (PAPVR): Malformation where some of the pulmonary veins drain into the right atrium or into a systemic vein rather than into the left atrium.

Mitral cleft: Division or fissure of the mitral valve, often associated with atrioventricular communications, which can lead to significant valvular regurgitation.

Information intended for healthcare professionals. This content may contain errors or truncated summaries. We recommend always verifying with the original source article. Delynov disclaims all responsibility regarding the use of this information. This document is not intended for patients or the general public.