Background: Fetal echocardiography has been used for non-invasive evaluation of human fetal cardiac anatomy, function and hemodynamics. The Tei index, a new Doppler index known to be independent of both ventricular geometry and heart rate, has recently been applied to the evaluation of myocardial performance.
Methods: In the present study, the Tei index was prospectively and longitudinally determined in 50 normal fetuses, 35 fetuses with intrauterine growth retardation (IUGR), 30 fetuses of diabetic mothers (DM) and 20 normal infants. The Tei index of both left and right ventricles was calculated from a Doppler ventricular inflow and outflow trace using the following formula: Tei index = (ICT + IRT)/ET, where ICT is isovolumetric contraction time; IRT, isovolumetric relaxation time; and ET, ejection time).
Results: The Tei index of the left ventricle decreased linearly with advancing gestational age during 18-33 weeks and decreased acceleratively with increasing gestational age after 34 weeks. The index of the right ventricle decreased slightly and linearly with advancing gestational age during 18-41 weeks. In neonates, the Tci index of the left and right ventricle increased immediately and transitorily after birth and decreased and stabilized after 24 h of life. From 18 to 26 weeks of gestation, the Tei indices in fetuses with IUGR and of DM were not significantly different from controls. However, from 27 to 40 weeks of gestation, the Tei indices in both fetuses with IUGR and of DM were significantly greater than controls.
Conclusions: This gradual decrease in the Tei index during gestation may represent the maturational or developmental alternation of myocardial performance in utero. Fetuses with IUGR and of DM may have abnormal myocardial performance in later gestation.