Background: Postnatal outcome of fetuses with hypoplastic left heart syndrome (HLHS) is mainly determined by right ventricular function. In the present study we used spatio-temporal image correlation (STIC) to assess right ventricular function of fetuses with HLHS.
Methods: Three-dimensional ultrasound with STIC technique was used to acquire heart images from fetuses that had HLHS and the normal controls, between 24(+0) and 37(+6) weeks of gestation. Right ventricular end-diastolic volume (RVEDV) and right ventricular end-systolic volume (RVESV) were determined using the virtual organ computer-aided analysis software, and the parameters of right ventricular function were calculated.
Results: Both RVEDV and RVESV were found to be significantly higher in fetuses with HLHS as compared to that in normal controls (P < 0.001). There were no significant differences in the parameters between fetuses with and without a visible left ventricular cavity (P > 0.05). Compared to fetuses with HLHS plus mild tricuspid regurgitation (TR), fetuses with HLHS plus severe TR exhibited lower right ventricular stroke volume (RVSV), right ventricular cardiac output (RVCO) and standardized RVCO (P < 0.05). The right ventricular ejection fraction (RVEF) was significantly lower in HLHS fetuses that had severe TR (P < 0.001).
Conclusion: As the right ventricle is solely responsible for maintenance of circulation, the right ventricular systolic function undergoes compensatory enhancement in fetuses with HLHS and mild TR, compared to that in normal controls. Size of the left ventricle does not significantly affect the right ventricular function in HLHS. However, right ventricular systolic function may be impaired prenatally in HLHS fetuses that have severe TR.
Keywords: Fetal hypoplastic left heart syndrome; Right ventricular function; Spatio-temporal image correlation.