Biventricular repair for right atrial isomerism

Utility of Three-Dimensional Printed Model in Biventricular Repair of Complex Congenital Cardiac Defects: Case Report and Review of Literature

Heterotaxy is a rare syndrome associated with cardiac complexity, anatomic variability and high morbidity and mortality. It is often challenging to visualize and provide an accurate diagnosis of the cardiac anatomy prior to surgery with the use of conventional imaging techniques. We report a unique case demonstrating how the use of three-dimensional (3D) cardiac printed model allowed us to better understand the anatomical complexity and plan a tailored surgical approach for successful biventricular repair in a patient with heterotaxy syndrome.

Human Laterality Disorders: Pathogenesis, Clinical Manifestations, Diagnosis, and Management

Human laterality disorders comprise a group of diseases characterized by abnormal location (situs) and orientation of thoraco-abdominal organs and vessels across the left-right axis. Situs inversus totalis is mirror image reversal of thoraco-abdominal organs/great vessels. Situs ambiguus, better known as heterotaxy, is abnormal arrangement of thoraco-abdominal organs across the left-right axis excluding situs inversus totalis. Heterotaxy, also referred to as atrial or atrial appendage isomerism, is characterized by abnormal location of left-sided or right-sided organs with loss of asymmetry of normally paired asymmetric organs. It is associated with a variety of anomalies involving the heart, great vessels, lungs and intra-abdominal organs. Right and left atrial isomerism are associated with multiple complex congenital cardiac and vascular anomalies, many of which are lethal when untreated. Isomerism may also affect the lungs, spleen, liver, gall bladder, and intestines. Innovative surgical therapy of heterotaxy/isomerism has reduced early mortality and markedly improved long-term prognosis.

The heterotaxy syndrome: associated congenital heart defects and management

Heterotaxy syndrome (HS) constitutes a spectrum of anomalies arising from embryological errors that result in abnormalities of lateralization involving thoraco-abdominal viscera and culminate in loss of normal asymmetric arrangement of these organs. Besides the unique challenges involved in planning and execution of surgical procedures aimed at correction or palliation of these anomalies, they have the potential to cause profound physiological and immunological consequences in the individual patient due to their cardiac and extra-cardiac manifestations. This article aims to review the literature on this rare and extraordinary subset of developmental anomalies with the intention of familiarizing the reader on the modes of presentation, manifestations, and the variations thereof while dealing with this anomaly. In our institutional experience with HS, 75 consecutive patients were seen between January 2011 and September 2018. Of these, 48 (64%) were confirmed to have isomerism of right atrial appendages (IRAA) and the rest had isomerism of left atrial appendages (ILAA). The cardiac and extra-cardiac manifestations of these patients were listed out. Fifty-four patients (34 with IRAA and 20 with ILAA) underwent 83 surgical procedures. While 49 patients were palliated on the univentricular pathway, 5 underwent biventricular repair. The in-hospital mortality was 7 (13%) in both groups combined (5 for patients with IRAA and 2 for ILAA). In conclusion, the surgical management of HS is associated with satisfactory outcomes in current era.

Impact of Era, Type of Isomerism, and Ventricular Morphology on Survival in Heterotaxy: Implications for Therapeutic Management

BACKGROUND

Heterotaxy has been demonstrated to reduce survival. There are several different subgroups of patients, however, and no single study has had a large number of patients and analyzed survival across the different subgroups such as patients born in different eras, patients with right and left isomerism, and patients with biventricular or functionally univentricular hearts. This study pools previously reported data from Kaplan-Meier curves and performs such subgroup analysis.

METHODS

A systematic review of the literature was performed to identify studies reporting survival of patients with the so-called "heterotaxy" by means of Kaplan-Meier survival curves. Data were extracted from these survival curves and then pooled together. A polynomial regression was then used to generate a pooled survival curve. This was done for all patients, those born in a more recent era, those with right and left isomerism, and those with biventricular or functionally univentricular hearts.

RESULTS

Those born in the more recent era (after 2000) had increased survival compared to the overall cohort. Those with left isomerism tended to have a survival benefit compared to those with right isomerism until about 16 years of age, beyond which those with right isomerism developed a survival benefit. Those with biventricular hearts had a survival benefit compared to those with left isomerism.

CONCLUSION

Survival in the so-called heterotaxy syndrome is based on several factors, which include era of birth, sidedness of isomerism, and whether the heart is biventricular or functionally univentricular.

Heterotaxy syndrome

Heterotaxy is defined as an abnormality where the internal thoraco-abdominal organs demonstrate abnormal arrangement across the left-right axis of the body. This broad term includes patients with a wide variety of very complex cardiac lesions. Patients with heterotaxy can be stratified into the subsets of asplenia syndrome and polysplenia syndrome, or the subsets of heterotaxy with isomerism of the right atrial appendages and heterotaxy with isomerism of the left atrial appendages. Treatment of patients with isomerism is determined by the nature and severity of the associated cardiac and extracardiac lesions. Most cardiac operations for patients with isomerism are palliative in nature, since normal anatomy is rarely achieved and mortality rates remain high for patients with heterotaxy syndrome. Patients with left isomerism in general have less severe cardiac malformations than those with right isomerism and, hence, more chance of biventricular repair. For almost all patients with right isomerism, and for many with left isomerism, biventricular repair will not be feasible, and all palliative protocols are then staging procedures prior to a Fontan-type repair. Recent advances in medical management, and improvements in surgical techniques have resulted in improved survival for these patients, and the surgical outcomes are comparable to those with Fontan circulation irrespective of the presence or absence of heterotaxy.

Biventricular repair in patients with heterotaxy syndrome

OBJECTIVE

Complex intracardiac and extracardiac anatomy is often confronted during biventricular repair in patients with heterotaxy syndrome. We examined factors affecting surgical outcomes in these patients.

METHODS

Between January 1990 and July 2007, 371 patients received a diagnosis of heterotaxy syndrome; 91 (91/371, 24.5%) underwent biventricular repair. Left atrial isomerism was present in 73% (66/91) and right atrial isomerism in 10% (9/91), with indeterminate atrial anatomy in 17% (16/91). Median age at biventricular repair was 6.8 months (5 days to 22.3 years). Systemic venous anomalies were present in 75 patients, pulmonary venous anomalies in 26, and endocardial cushion defects in 36. Transposition complexes were present in 15 patients with atrioventricular discordance in 10; 8 underwent double switch, 2 received a physiologic repair, 2 underwent arterial switch, and 3 underwent the Rastelli operation. Other conotruncal anomalies included double-outlet right ventricle in 10 patients, tetralogy of Fallot in 3, and hemitruncus in 2. Separation of systemic from pulmonary venous return included intra-atrial baffling in 48 patients and extracardiac grafting in 2. Combined lesions were common, occurring in 99% (90/91). Statistical analysis with Kaplan-Meier and Cox proportional hazards models were performed.

RESULTS

Average follow-up was 44.9 +/- 57.5 months (3 days to 189.3 months). Kaplan-Meier estimated survival was 93.4% at 10 years; unbalanced complete atrioventricular canal was the only risk factor for mortality (P = .006). Subsequent procedures were common with a 10-year freedom from reoperation or reintervention of 38% +/- 7.5%. Arrhythmias occurred in 36 (39.6%) patients; bradyarrhythmia in 27 (29.7%) and tachyarrhythmia in 15 (16.5%). Freedom from any arrhythmia was 53.9% +/- 6.7% at 10 years.

CONCLUSIONS

Excellent survival for patients with heterotaxy undergoing biventricular repair can be expected, even for multiple, complex lesions. Reintervention is common, and arrhythmia is a long-term concern. This experience shows that patients with heterotaxy syndrome and complex cardiac anatomy can be considered for biventricular repair. Patients with unbalanced complete atrioventricular canal are a high-risk group for which selection criteria are particularly important.