CHANGES IN LEFT-VENTRICULAR DIASTOLIC FILLING PATTERNS BEFORE AND AFTER THE CLOSURE OF THE DUCTUS-ARTERIOSUS IN VERY-LOW-BIRTH-WEIGHT INFANTS

To evaluate serial changes in left ventricular diastolic filling patte rns in preterm infants, we performed echocardiographic examinations in 18 very-low-birth weight infants and 20 fullterm infants before and a fter the closure of the ductus arteriosus. In the fullterm infants, th e ductal closure induced significant decreases in the peak velocity an d flow velocity integral of early diastole, first third filling fracti on, and mitral stroke volume. In the preterm infants, by contrast, the re were significant increases in the flow velocity integral of early d iastole, first third filling fraction, and mitral stroke volume after the ductal closure. No differences following the ductal closure were f ound in the atrial phase of filling and peak filling rate normalized t o stroke volume in either group. When the ductus arteriosus was open, essentially the same left-to-right shunting of the ductus arteriosus w as detected in both preterm and fullterm infants, but the Doppler flow patterns of the patent foramen ovale were different: the fullterm inf ants had a single flow peak mainly during ventricular late systole and early diastole, but the preterm infants had two or three flow peaks w ith;;early equal amplitudes lasting from ventricular systole to diasto le, which resembled the Doppler flow pattern of atrial septal defect. Only a faint Doppler flow signal of the foramen ovale was observed aft er the ductus arteriosus closed. Our results obtained from the preterm s suggest that the left-to-right shunt through the foramen ovale may b e one important factor to alter the Doppler transmitral filling patter ns during the fetal to neonatal cardiovascular changes. (C) 1997 Tohok u University Medical Press.