Among critical congenital heart lesions, hypoplastic left heart syndrome (HLHS) and related single right ventricle (RV) anomalies are associated with the highest morbidity and mortality. The first stage in palliation for patients with these defects is the Norwood procedure. The essential components of the Norwood procedure include (1) an atrial septectomy, (2) anastomosis of the proximal pulmonary artery to the aorta with homograft augmentation of the aortic arch, and (3) establishment of a source of pulmonary blood flow, with either a modified Blalock-Taussig shunt (MBTS) or the right ventricle to pulmonary artery (RV-to-PA) shunt. In May 2005, the Pediatric Heart Network began a multi-center, randomized trial, the Single Ventricle Reconstruction (SVR) Trial, comparing outcomes in subjects with HLHS or other single RV anomalies palliated using the Norwood procedure with either a MBTS or the RV-to-PA shunt. The primary outcome of this trial was freedom from death or cardiac transplantation by 12 months post-randomization.~The Single Ventricle Reconstruction Extension (SVR II) Study is an extension of the SVR Trial that compares clinical outcomes and RV performance following the RV-to-PA shunt versus MBTS modifications of the Norwood procedure in subjects at 6 years post-randomization. Data is collected annually between ages 2 and 6 years, as well as before and after the Fontan surgery. Vital status and medical history is ascertained annually until the last enrolled subject is 6 years old. Data is obtained through medical record review, phone interview with the parent or guardian, electrocardiography (ECG), core laboratory analysis of echocardiographic images and Holter monitors, and completion of questionnaires regarding neurodevelopmental outcomes, behavior, health-related quality of life, and family functioning. The primary outcome variable in SVR II will be freedom from death or cardiac transplantation at 6 years post-randomization. All subjects who were randomized in the SVR trial will be included in analysis of this endpoint.
The Single Ventricle Reconstruction (SVR) Trial looked at how infants with single ventricle heart defects did after the first stage of surgery (Norwood operation). Infants enrolled in the trial got one of two kinds of shunts during the Norwood; a modified Blalock-Taussig shunt (MBTS) or right ventricle to pulmonary artery shunt (RV-to-PA shunt).~The purpose of this study is to learn if children (2-6 years of age) who were enrolled in the SVR Trial do better with one of the two shunts (MBTS or RV-to-PA) in the years after surgery.