In hypoplastic left heart patients is Sano shunt compared with modified Blalock-Taussig shunt associated with deleterious effects on ventricular performance?

Abstract

A best evidence topic in congenital cardiac surgery was written according to a structured protocol. The question addressed was: in hypoplastic left heart patients is Sano shunt compared with modified Blalock-Taussig (mBT) shunt associated with deleterious effects on ventricular performance? Sano shunt modification of Norwood procedure involves construction of a right ventricle to pulmonary artery (RV-PA) conduit as an alternative source of pulmonary blood flow. Compared with the mBT shunt, the RV-PA conduit provides a more stable haemodynamic state in the immediate postoperative period and is reported to be associated with lower interstage mortality. However, concerns regarding the impact of ventriculotomy on short- and long-term performance of single ventricle have been expressed. Altogether 101 papers were found using the reported search terms, from which seven represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. None of the echocardiographic or clinical outcome studies showed poor ventricular performance after ventriculotomy of the systemic RV for construction of Sano shunt. A small autopsy study of 11 patients showed greater remodelling of the ventricular myocardial extracellular matrix in patients with RV-PA conduit with potential implications for poor ventricular performance. We conclude that the current available evidence, although weak, does not show any adverse effects of ventriculotomy on ventricular performance in patients with Sano shunt in the short- and medium-term. However, all the existing studies are limited by small numbers, non-randomised design and retrospective nature with failure of correlation of echocardiographic indices to clinical outcomes. It is expected that the Pediatric Heart Network randomised controlled trial will address this important issue.