Long-term Outcomes of Children With HLHS (Hypoplastic Left Heart Syndrome) and the Impact of Norwood Shunt Type (A Study Conducted by the Pediatric Heart Network)
Long-term Outcomes of Children With HLHS (Hypoplastic Left Heart Syndrome) and the Impact of Norwood Shunt Type (A Study Conducted by the Pediatric Heart Network)
The purpose of this study is to compare direct and indirect measures of right ventricular (RV) systolic and diastolic function between 11 year old subjects who had been randomly assigned to receive a right ventricle to pulmonary artery shunt (RVPAS) vs. a modified Blalock-Taussig shunt (MBTS) at the time of the Norwood operation.
The Single Ventricle Reconstruction (SVR) trial was the first multicenter, randomized clinical trial to compare two operations in the field of congenital heart disease.8,11 Children with HLHS and other related single RV lesions were enrolled and randomized to receive either a MBTS or a RVPAS at the time of the initial Norwood procedure. This landmark study provided extraordinary insight not only into the consequences of both shunt types, but also into the course, treatment responses and short- and mid-term outcomes for these medically complex patients. Through the SVR Trial and SVR Extension Study (SVR II), outcomes, including but not limited to the primary outcome of transplant-free survival, have now been evaluated in this patient cohort when the last enrolled patient reached 12 months and again at 3 years of age. While early post-operative transplant-free survival during the interstage period7 and at one year8 was better for those children randomized to a RVPAS, survival by the 3-year evaluation appeared equivalent between the two shunt types. Moreover, RVEF was somewhat diminished and the number of interventions was higher in the RVPAS group.12 These findings raised concern that the RV dysfunction in the RVPAS group may be progressive, leading to significantly worse long-term outcomes; if so, the benefits of the RVPAS for short-term survival may be outweighed by longer-term morbidity and mortality. Thus, the optimal surgical approach for newborns with HLHS and related single RV lesions remains unclear.
The Pediatric Heart Network (PHN) Investigators have a unique opportunity and responsibility to analyze the effect of the type of systemic-to-pulmonary artery shunt placed during the Norwood procedure on longer-term survival, as well as to define its effect on other long-term outcomes in this multi-institutional cohort of exquisitely characterized subjects with single RV lesions. As subjects enrolled in the SVR cohort approach a decade of age, the investigators aim: 1) to determine if shunt type at the time of Norwood operation is associated with any long-term differences in cardiac function, survival, or contributors to quality of life; and 2) to characterize long-term outcomes and determine risk factors other than shunt type for adverse long-term outcomes in children with HLHS and other related single ventricle anomalies.
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