An Angiographic Predictor of Pulmonary Artery Stenosis After the Norwood-Sano Operation for Hypoplastic Left Heart Syndrome

Background: The Sano modification of the Norwood operation (NO) for hypoplastic left heart syndrome (HLHS) includes placement of a right ventricle to pulmonary artery (RV to PA) conduit. Branch pulmonary artery stenosis (PS) is a recognized complication. The goal of this study was to determine angiographic predictors of future PS at the time of pre-stage 2 cardiac catheterization (PS2C).

Methods: Data from patients with HLHS who had a NO with RV to PA conduit from 2005 to 2009 and who underwent PS2C were reviewed retrospectively. Nakata and McGoon indices were calculated in the traditional fashion and Modified Nakata and McGoon indices were calculated using the narrowest branch PA diameters.

Results: Thirty-three patients had NO and 28 patients had PS2C. Mean follow-up was 35.8 ± 7.5 months. Ten (36%) patients developed significant left PS, 2 requiring angioplasty and 8 requiring stent placement, a median of 15.2 months after PS2C (IQR 1.2, 32.8). The Modified Nakata index was predictive of future left PS (ROC curve AUC 0.811), with a cut-off of 135mm2/m2 having a sensitivity of 100% and specificity of 72.2%.

Conclusions: A Modified Nakata index of less than 135mm2/m2 at PS2C predicts future development of left PS in patients with HLHS after the NO with RV to PA conduit. Surgical pulmonary arterioplasty at the time of stage 2 surgical palliation may obviate the need for future interventions.