The New Zealand Norwood Procedure Experience: 22-Year Cumulative Review

Babies born with a functional single ventricle heart and systemic outflow tract obstruction may require a Norwood (NW) procedure as the first of three staged procedures to obtain a Fontan circulation. This procedure and the following treatment pathway are associated with significant mortality. Risk factors for the Norwood procedure and the subsequent pathway are not necessarily the same. To identify these factors within New Zealand, the collective experience with the Norwood procedure was examined.

Charts from 133 New Zealand children undergoing Norwood procedure from 1992 to 2014 were examined. Deaths were assigned as "early" (30-day or in-hospital) or "late" (based on timeframe from the Norwood procedure). Cardiac anatomic, patient demographic and surgery related variables were examined. Important risk factors were identified using univariate and multivariate analysis. Kaplan-Meier survival curves were calculated.

Survival following the Norwood procedure was 83%. Overall survival was 67% at six months, 65% at one year, and 63% at five years. Size of the ascending aorta appeared as an important risk factor with "early" death while New Zealand deprivation index and low birth weight appeared more important for "late" death. These factors each impacted overall survival.

The Norwood procedure and subsequent medical treatment carries significant mortality in New Zealand. Cardiac anatomical factors affect survival of the immediate Norwood procedure whereas social factors weigh more significantly on longer term survival. Nevertheless, both anatomical and social factors carry real survival risk.