Long-Term Hypoplastic Left Heart Syndrome Outcomes and Norwood Shunt Type

Quick Takes

  • There was no difference in transplant-free survival in patients with right ventricle-to-pulmonary artery shunt (RVPAS; 59%) compared with modified Blalock-Taussig-Thomas Shunt (mBTTS; 54%), p = 0.11.
  • RVEF by CMR was similar between the shunt groups (RVPAS, 51 ± 9.6 and mBTTS, 52 ± 7.4, p = 0.43).
  • The RVPAS group had a higher cumulative incidence of protein-losing enteropathy (5% vs. 2%; p = 0.04) and of catheter interventions (14 vs. 10 per 100 patient-years) but had similar rates of other complications.

Study Questions:

What are the longitudinal outcomes and their risk factors through 12 years of age for children enrolled in the SVR (Single Ventricle Reconstruction) trial?


Annual medical history was collected through records review and telephone interviews. Cardiac magnetic resonance imaging (CMR), echocardiogram, and cycle ergometry cardiopulmonary exercise tests were performed at 10-14 years of age among participants with Fontan circulation. Differences in transplant-free survival and complication rates were identified through 12 years of age. The primary study outcome was right ventricular ejection fraction (RVEF) by CMR, and primary analyses were according to shunt type received.


Among 549 participants enrolled in the original SVR trial, 237 of 313 transplant-free survivors participated in SVRIII (Long-Term Outcomes of Children With Hypoplastic Left Heart Syndrome and the Impact of Norwood Shunt Type). RVEF by CMR was similar in the shunt groups (right ventricle-to-pulmonary artery shunt [RVPAS], 51 ± 9.6 and modified Blalock-Taussig-Thomas Shunt [mBTTS], 52 ± 7.4; p = 0.43). There was no difference between shunt groups in transplant-free survival by 12 years of age (59% in the RVPAS group vs. 54% in the mBTTS group). The RVPAS group had a higher cumulative incidence of protein-losing-enteropathy (5% vs. 2%, p = 0.04) and of catheter interventions (14 vs. 10 per 100 patient-years; p = 0.01), but had similar rates of or other complications.


The authors conclude that by 12 years after the Norwood operation, shunt type has little association with RVEF, peak VO2, complication rates, and transplant-free survival. Low transplant-free survival is a significant concern for this patient population.


The landmark SVR trial was the first randomized multicenter trial to compare surgical techniques for congenital heart disease. Transplant-free survival was superior in the RVPAS group at 1 year, although this difference did not persist at 6 years. This study cohort has become important in understanding the intermediate- and long-term outcomes for infants with hypoplastic left heart syndrome (HLHS) undergoing staged palliation. Shunt type does not impact RV function or transplant survival, although patients with RVPAS had higher rates of protein-losing enteropathy and need for transcatheter interventions as compared with those with mBTTS. Most concerning in this study is the low transplant-free survival rate of just over 50% by time of enrollment in SVRIII. The vast majority of mortality occurs in the first year of life. While it is possible that these may be better in the current era with potentially improved Stage I surgical outcomes improved interstage monitoring, continued work is required to improve outcomes for this complex patient population.

Clinical Topics: Cardiac Surgery, Congenital Heart Disease and Pediatric Cardiology, Invasive Cardiovascular Angiography and Intervention, Cardiac Surgery and CHD and Pediatrics, Congenital Heart Disease, CHD and Pediatrics and Interventions, Interventions and Structural Heart Disease

Keywords: Heart Defects, Congenital, Hypoplastic Left Heart Syndrome, Norwood Procedures

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