Perinatal Changes in Fetal Ventricular Geometry, Myocardial Performance, and Cardiac Function in Normal Term Pregnancies.

BACKGROUND: The fetal heart at term is exposed to an increase in hemodynamic work as a consequence of fetal growth, increased circulating volume, and alteration in loading patterns due to maturational changes in fetoplacental circulation. The extent to which these cardiovascular changes influence human fetal and neonatal cardiac adaptation has not been fully elucidated. The aim of this study was to evaluate perinatal cardiovascular changes in ventricular geometry and myocardial performance in normal term fetuses.

METHODS: Prospective study of 108 uncomplicated pregnancies delivering at term. M-mode, two-dimensional or B-mode, pulsed wave Doppler, pulsed wave tissue Doppler, and two-dimensional speckle-tracking imaging were performed a few days before and within 24 hours of birth.

RESULTS: Analysis of paired fetal and neonatal echoes demonstrated significant perinatal changes (P < .0001 for all) in right ventricular (RV) and left ventricular (LV) geometry (RV/LV end-diastolic dimension ratio, 1.2 vs 0.8; RV sphericity index, 0.53 vs 0.40; LV sphericity index, 0.46 vs 0.49). There were corresponding significant (P < .001 for all) perinatal changes in global myocardial performance: LV myocardial performance index, 0.60 versus 0.47; RV myocardial performance index, 0.61 versus 0.42; systolic function: LV longitudinal systolic strain rate, -1.4/sec versus -1.0/sec; RV longitudinal systolic strain rate, -1.5/sec versus -1.0/sec; RV S', 5.3 cm/sec versus 6.5 cm/sec; and diastolic function: LV E'/A', 0.8 versus 1.1.

CONCLUSIONS: The findings support the concept that the perinatal period is associated with major changes in fetal ventricular geometry and cardiac function in response to significant alterations in loading conditions. Improved knowledge of perinatal cardiac changes in normal fetuses could facilitate better understanding of cardiac adaptation in normal and pathological pregnancies.