Tissue Doppler time intervals and derived indices in hypoplastic left heart syndrome

To describe tissue Doppler time intervals and derived indices in hypoplastic left heart syndrome (HLHS) across surgical stages, taking account of age-related changes in the heart rate. Correlation of the myocardial performance index (MPI) and the systolic to diastolic (S:D) time ratio with other echocardiographic and magnetic resonance imaging (MRI) measures of cardiac performance.

Fifty-seven patients at different stages of HLHS palliation were studied prospectively using tissue Doppler imaging of the right ventricular free wall, with simultaneous cardiac MRI in the majority. Both isovolumic contraction time and isovolumic relaxation time were prolonged compared with the normal left and right ventricle: median (range) z-scores for the tricuspid annulus 1.9 (-1.2 to 9.3) and 1.3 (-2.0 to 5.5), respectively. When adjusted for heart rate, the ejection, systolic, and diastolic times in HLHS were not significantly different from published normal data. The MPI was increased at all surgical stages in HLHS. Neither MPI nor heart rate-specific S:D time ratio z-score correlated with MRI ejection fraction or indexed cardiac output when the confounding effect of significant tricuspid regurgitation was taken into consideration.

The prolongation in isovolumic relaxation and contraction times may be due to adaptation or reduced myocardial performance. Differences in the S:D time ratio between surgical stages can be accounted for by the heart rate alone. Neither MPI z-score nor S:D z-score correlated with MRI or other echocardiographic indices of systolic or diastolic function with the exception of a negative correlation between central venous pressure and S:D ratio z-score.