GESTATIONAL AGE-RELATED AND GROWTH-RELATED ALTERATIONS IN FETAL RIGHTAND LEFT-VENTRICULAR DIASTOLIC FILLING PATTERNS

To evaluate the effects of gestational age on left and right ventricul ar diastolic filling in human fetuses, we retrospectively reviewed the diastolic flow velocity patterns through mitral and tricuspid valves in 307 normal fetuses aged 17 to 39 weeks' gestation. The subjects wer e divided into 3 age groups; 17 to 24 weeks, 25 to 31 weeks, and 32 to 39 weeks. The variables measured were peak flow velocities of early d iastole (peak E wave), of atrial contraction (peak A wave), and the ve locity ratio (peak E/A ratio). As a whole, the transmitral peak E wave and peak E/A ratio correlated with age using a second-order polynomia l curve fit. The strength of the linear correlation between age and tr ansmitral peak E wave and peak E/A ratio and the slope of the relation were greater in the group aged 32 to 39 weeks than in group aged 25 t o 31 weeks. Similar temporal change was observed in the relation betwe en age, transtricuspid peak E wave, and peak E/A ratio. The peak A wav e for both atrioventricular valves showed little change with gestation al age. Contrary to the accepted concept that fetal peak E wave and pe ak E/A ratio increases linearly with aging, this study shows that earl y diastolic filling increases mainly after 25 weeks' gestation. We spe culate that the maturational changes in ventricular properties in huma n fetuses accelerate after midgestation. (C) 1997 by Excerpta Medica, Inc.