The Impact of Dominant Ventricle Morphology on Palliation Outcomes of Single Ventricle Anomalies

Background. Differences in right ventricle and tricuspid valve structure compared with left ventricle and mitral valve structure make them less equipped to support the systemic circulation long term, with subsequent systemic right ventricle failure. We examined the effect of dominant ventricle morphology on single ventricle palliation outcomes. Methods. We grouped 530 neonates who underwent first-stage palliation into two groups based on dominant ventricle morphology: right dominant ventricle (RV group; n = 302, 57%) and left dominant ventricle or functional single ventricle with two well-formed ventricles (LV group; n = 228, 43%). Comparisons of hospital outcomes, interstage mortality, progression to subsequent palliation stages, and late survival was performed, and factors affecting outcomes were examined. Results. After first-stage palliation, the RV group and LV group, respectively, had comparable extracorporeal membrane oxygenation requirements (12% versus 11%, p = 0.648), unplanned reoperation (12% versus 13%, p = 0.586), and hospital death (16% versus 13%, p = 0.437). Among hospital survivors, interstage mortality (11% versus 9%, p = 0.509) and progression to Glenn operation (89% versus 84%, p = 0.182) were comparable; however, death after Glenn was higher in the RV group (10%, versus LV group 4%, p = 0.020) with a trend for lower 8-year survival (66% versus 73%, p = 0.081). On multivariable analysis, dominant RV was not associated with mortality (hazard ratio 0.75, 95% confidence interval: 0.6 to 1.0, p = 0.081), whereas factors such as genetic syndromes, weight 2.5 kg or less, underlying cardiac anomaly, and first-stage palliation type affected survival. Conclusions. At midterm follow-up, underlying cardiac anomaly and patient characteristics affect single ventricle palliation outcomes more than dominant ventricular morphology. As right ventricle and associated tricuspid valve failure might occur at late stages, the impact of dominant ventricular morphology on long-term outcomes requires further assessment. (C) 2016 by The Society of Thoracic Surgeons