The effect of morphologic subtype on outcomes following the Sano-Norwood procedure

Controversy exists concerning outcomes of patients with different morphologic subtypes of hypoplastic left heart syndrome undergoing the Norwood procedure, in particular, aortic atresia-mitral stenosis (AA-MS) patients receiving a systemic-pulmonary modified Blalock-Taussig (mBT) shunt. We sought to determine the influence of known risk factors and morphology on early survival in our cohort of Sano-Norwood patients with right ventricle-pulmonary artery (RV-PA) conduits as the source of pulmonary blood flow.

We studied early survival in patients with Sano-modified Norwood procedures from 2002 to 2010 and included both typical and atypical (including unbalanced atrioventricular canal defect) morphologic variants. We included a comparison group composed of classical Norwood patients with mBT shunts.

Of 264 Sano-Norwood patients, 49 had AA-MS and 30 had atypical morphologies. Weight ≤ 2.5 kg was associated with a poorer 1-year survival (P = 0.0007), though ascending aorta (AscAo) size <2.0 mm was not. We did not observe a difference in 30-day or 1-year Kaplan-Meier (K-M) survival across typical morphologic variants for either a Sano or mBTS group. Atypical variants exhibited a trend towards lower 30-day and 1-year survival in both Sano and mBTS groups though this was not significant. Direct comparison of 30-day K-M survival for Sano versus mBTS in AA-MS patients showed similar outcomes (P = NS).

Use of the RV-PA conduit results in good early survival, even in those with a small AscAo size. Atypical morphologic variants seem to do worse irrespective of the Sano or mBTS group. Further studies will be required to determine conclusively whether the RV-PA shunt confers protective effects in the AA-MS subgroup compared with the mBTS.