Impact of Initial Shunt Type on Echocardiographic Indices in Children After Single Right Ventricle Palliations

Abstract

Background Heart size and function in children with single right ventricle (RV) anomalies may be influenced by shunt type at the Norwood procedure. We sought to identify shunt-related differences during early childhood after staged surgical palliations using echocardiography. Methods We compared echocardiographic indices of RV, neoaortic, and tricuspid valve size and function at 14 months, pre-Fontan, and 6 years in 241 subjects randomized to a Norwood procedure using either the modified Blalock-Taussig shunt or RV-to-pulmonary-artery shunt. Results At 6 years, the shunt groups did not differ significantly in any measure except for increased indexed neoaortic area in the modified Blalock-Taussig shunt. RV ejection fraction improved between pre-Fontan and 6 years in the RV-to-pulmonary artery shunt group but was stable in the modified Blalock-Taussig shunt group. For the entire cohort, RV diastolic and systolic size and functional indices were improved at 6 years compared with earlier measurements, and indexed tricuspid and neoaortic annular area decreased from 14 months to 6 years. The prevalence of ≥moderate tricuspid and neoaortic regurgitation was uncommon and did not vary by group or time period. Diminished RV ejection fraction at the 14-month study was predictive of late death/transplant; the hazard of late death/transplant when RV ejection fraction was <40% was tripled (hazard ratio, 3.18; 95% CI, 1.41-7.17). Conclusions By 6 years after staged palliation, shunt type has not impacted RV size and function, and RV and valvar size and function show beneficial remodeling. Poor RV systolic function at 14 months predicts worse late survival independent of the initial shunt type. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT00115934.

Keywords: Norwood procedures; child; diastole; echocardiography; humans.

Figures

Figure 1.

Graph comparing right ventricular ejection fraction (left panel) and fractional area change (right panel) for the cohort with paired studies at the 14 months, pre-Fontan, and 6-year intervals. There was a significant increase in both the ejection fraction and fractional area change from the pre-Fontan to the 6-year echocardiogram. There was a trend toward increased right ventricular ejection fraction from 14 months to 6 years (p=0.06), but fractional area change was similar between those stages.

Figure 2.

Similar to Figure 1, this graph compares right ventricular ejection fraction (left panel) and fractional area change (right panel) between the modified Blalock-Taussig shunt (MBTS) and RV-to-pulmonary artery shunt (RVPAS) groups who had paired studies at the 14 months, pre-Fontan, and 6-year intervals. From the pre-Fontan to the 6-year echocardiogram, both ejection fraction and fractional area change significantly increased in the RVPAS when compared to the interval change in the MBTS group. Ejection fraction and fractional area change were similar for both shunt groups when comparing the 14 months and 6-year studies.

Figure 3.

Graph comparing indexed right ventricular end-diastolic volume (left panel) and end-diastolic area (right panel) for the cohort with paired studies at the 14 months, pre-Fontan, and 6-year intervals. There was a significant decrease in both the end-diastolic volume and area from the pre-Fontan to the 6-year echocardiogram. End-diastolic volume was also decreased when comparing the 14 months and 6-year studies, but end-diastolic areas were similar.

Figure 4.

Graph comparing indexed neo-aortic valve annular area z-score (left panel) and tricuspid valve annular area z-score (right panel) for the cohort with paired studies at the 14 months, pre-Fontan, and 6-year intervals. The annular z-score decreased significantly for both the neo-aortic and tricuspid valves between 14 months and 6 years for the cohort with no differences in either valve z-score between pre-Fontan and 6 year studies.