[Left and right ventricular cardiac outputs in early neonatal periods examined using Doppler echocardiography]

To evaluate early neonatal circulatory adaptation, left and right ventricular cardiac outputs were examined in 10 normal neonates using Doppler echocardiography. Serial examinations were performed until ductal closure was confirmed. Two-dimensional echocardiography and Doppler echocardiography were used to evaluate structures of the heart and great vessels and flow within them. Then, the diameters of the ascending aorta (dAo) and pulmonary artery (dPA) were measured using M-mode echocardiography. The flow velocity patterns of the ascending aorta and pulmonary artery were recorded, measuring mean aortic (VAo) and pulmonary artery velocities (VPA). Left (LVCO) and right ventricular cardiac outputs (RVCO) were calculated as follows: LVCO = (dAo)2/4 x pi x VAo x 60, RVCO = (dPA)2/4 x pi x VPA x 60. 1. Patency of the ductus arteriosus was confirmed by the shunt through it in all neonates initially examined. The initial velocity pattern of the ductal shunts was bidirectional (9/10) or continuous left-to-right (1/10). The flow velocity pattern changed to continuous left-to-right in most neonates, and spontaneous closure of the ductus was confirmed at the age of 13 to 64.5 (mean 31.4) hrs. 2. Left-to-right shunt through the stretched foramen ovale was noted in six neonates temporarily. 3. As for the arterial diameter, dAo did not change, but dPA decreased at the time of spontaneous closure of the ductus. 4. Concerning mean aortic velocity, VAo increased when a continuous ductal left-to-right shunt was initially suspected, while VPA increased when spontaneous closure of the ductus was confirmed. 5. For cardiac output, LVCO (ml/min) changed from 618.4----718.3----562.7, while RVCO showed no change (576.1----546.5----557.8) according to a ductal flow change from bidirectional to continuous left-to-right and finally to no shunt. The LVCO/RVCO ratio increased with increasing age and (in 7/9) the maximal rate was noted when the continuous left-to-right ductal shunt was confirmed. The increased LVCO contributed to the increased LVCO/RVCO ratio. Using this method, serial evaluations of two ventricular cardiac outputs could be made.