Clinical Characteristics and Independent Factors Related to Long-Term Outcomes in Patients with Left Isomerism

Clinical implications of airway anomalies and stenosis in patients with heterotaxy syndrome

In heterotaxy syndrome, bronchopulmonary situs usually reflects atrial situs, resulting in either right (RAI) or left atrial isomerism (LAI). This study determines airway anomalies and its implications in patients with heterotaxy. This retrospective study included 223 patients with heterotaxy syndrome who received an integrated cardiac computed tomography evaluation. Patient database from 1995 to 2020 was reviewed. The patients were examined by a congenital heart disease team comprising pediatric cardiologists, radiologists, pulmonologists, and cardiovascular surgeons. Among the 223 patients, 189 (84.8%, M/F  =  1.66) had RAI and 29 had LAI (13.0%, M/F  =  0.71). Five patients had indeterminate isomerism (2.2%, M/F  = 1.5). Discordant bronchopulmonary and atrial situs occurred in 4% patients, while discordant bronchopulmonary, atrial, and splenic situs occurred in 23.2% patients. Lower airway stenosis was observed in 61 patients (27.4%), including 27.5%, 20.7%, and 60% RAI, LAI, and indeterminate isomerism patients, respectively (p = 0.189). One patient had an intrinsic long segment lower tracheal stenosis and received slide tracheoplasty. Initial cardiac operation was performed in 213 patients. Higher surgical mortality occurred in patients with RAI (19.5% vs. none for LAI and indeterminate isomerism, p = 0.038). In patients with RAI, lower airway anomaly/stenosis increased the duration of ventilator usage (p = 0.030) but did not affect surgical mortality. Total anomalous pulmonary venous return to systemic veins and pulmonary venous stenosis were major surgical risk factors. Bronchopulmonary isomerism shares a similar isomeric pattern to cardiac atrial appendage. Lower airway anomalies/stenosis was common in patients with heterotaxy, resulting in prolonged ventilator therapy in patients with RAI.

Twin atrioventricular nodes, arrhythmias, and survival in pediatric and adult patients with heterotaxy syndrome

BACKGROUND

Heterotaxy syndrome is likely to involve arrhythmias from associated conduction system abnormalities, which are distinct in different subtypes of isomerism and may change further after interventions and remodeling.

OBJECTIVE

The purpose of this study was to understand the risk of arrhythmias and its relation to isomerism subtypes.

METHODS

Patients diagnosed between 1980 and 2019 as having heterotaxy syndrome were enrolled and grouped as right atrial isomerism (RAI), left atrial isomerism (LAI), or indeterminate isomerism.

RESULTS

Of the 366 patients enrolled, 326 (89.1%) had RAI, 35 (9.6%) LAI, and 5 (1.4%) indeterminate isomerism; 71 (19.4%) patients were adults. Arrhythmias occurred in 37.2% of patients (109 supraventricular tachycardia [SVT], 8 atrial fibrillation/flutter, 12 ventricular tachycardia, and 14 paced bradycardia). Freedom from arrhythmias by the age of 1, 5, 10, 20, and 40 years was 0.849, 0.680, 0.550, 0.413, and 0.053, respectively. Twin atrioventricular nodes were identified in 51.5% of patients with RAI, 8.7% of patients with LAI, and 40.0% of patients with indeterminate isomerism and were the key predictors of SVT. Indeterminate isomerism was also a risk factor for SVT. Other forms of tachycardia appeared relatively late. Sinus bradycardia with junctional rhythm was common in LAI (48.7%) and less in indeterminate isomerism (20.0%), with none occurring in RAI. Only in patients with RAI who showed the poorest survival, ventricular tachycardia worsened the long-term survival.

CONCLUSION

RAI was the predominant subtype of heterotaxy in this cohort. Collectively, the median RAI/LAI ratio was 0.731 and 5.450 in Western and East Asian studies, respectively. Arrhythmias, tachycardia, or paced bradycardia were common, but the spectrum was distinct among subtypes.