Ventricular filling patterns of the right and left ventricles in normally grown fetuses: A longitudinal follow-up study from early intrauterine life to age 1 year, ,

Objective: Our goal was to determine the effects of advancing age on the Doppler diastolic filling indexes from early gestation to 1 year of life. Study Design: Seventy-nine fetuses were studied. Initial Doppler studies were started at about the 16th week of gestation and repeated every 4-6 weeks until term, on postnatal day 1 and 2, and at ages 6 weeks, 6 months, and 12 months. A minimum of 5 returning Doppler waveforms were traced and analyzed for (1) peak early flow velocity, (2) late peak atrial flow velocity, (3) total area area under the curve, and (4) the acceleration and deceleration phases. The stiffness of the ventricles was estimated. Slopes of the curves for each of the parameters were analyzed for differences across time periods and between right and left ventricles. Results: (1) Heart rate significantly decreased with advancing age. (2) Left ventricular and right ventricular peak early flow velocity and late peak atrial flow velocity significantly increased during fetal life but not during the 1st year. (3) Atrial predominance was found during fetal life but not during the first year. (4) The deceleration phase of filling significantly increased during the fetal period. (5) Ventricular stiffness progressively decreased during the fetal period. (6) Increased ventricular filling shifted from a right-sided dominance in utero to a left-sided dominance after birth. Conclusions: (1) Fetuses have stiffer fetal ventricles than neonates. (2) The diastolic filling patterns in normally grown fetuses mimic those of the diseased adult heart. We speculate that this maturation process may be affected in fetuses born prematurely or small for gestational age. (Am J Obstet Gynecol 1999;180:849-58.)