Right Ventricular Mechanics in the Fetus with Hypoplastic Left Heart Syndrome

Background: Right ventricular mechanics influence outcomes in patients with hypoplastic left heart syndrome (HLHS). The aim of this study was to determine whether differences in right ventricular performance have their origins in fetal life and if the architectural character of the hypoplastic left ventricle affects right ventricular mechanics. Methods: The first complete fetal echocardiograms after 17 weeks' gestation were reviewed in 84 fetuses with HLHS and in 115 gestational age-matched normal controls. Inflow, outflow, and myocardial tissue Doppler velocities were measured. E/A and E/e' ratios and right ventricular myocardial performance index were calculated. Results: In fetuses with HLHS, there were lower tricuspid E/A ratios (mean, 0.6 +/- 0.1 vs 0.7 +/- 0.1; P < .001), higher E/e' ratios (mean, 8.1 +/- 2.6 vs 7.0 +/- 1.3; P = .006), and higher right ventricular myocardial performance indices (mean, 0.47 +/- 0.14 vs 0.40 +/- 0.10; P < .001) compared with controls. Among fetuses with HLHS grouped according to left ventricular architecture, those with left ventricular endocardial fibroelastosis had the most striking differences in right ventricular mechanics. Conclusions: Right ventricular mechanics are different from normal in fetuses with HLHS and are influenced by the presence of left ventricular endocardial fibroelastosis. These differences precede the imposition of undue loading conditions as a consequence of surgical palliation and may offer clues to the development of later right ventricular failure.