Doppler echocardiographic evaluation of left ventricular output and left ventricular diastolic filling changes in the first day of life

Abstract

The aim of this study was to evaluate the changes in Doppler transmitral flow patterns during the 1st d of life. Doppler echocardiography of the ascending aorta and mitral valve was performed serially in 20 normal neonates at 2, 12, and 24 h of age. A computer-interfaced digitizer pad was used to measure the following: ascending aorta flow velocity-time integral, total diastolic filling flow velocity-time integral, flow velocity-time integral of early diastolic filling, and flow velocity-time integral of atrial contraction. The inner diameter of the ductus arteriosus was 4.2 ± 0.6 mm at 2 h of age, 2.3 ± 0.5 mm at 12 h of age, and had closed in 17 of 20 neonates (85%) by 24 h of age. The ascending aorta flow velocity-time integral and total diastolic filling flow velocity-time integral, which were high at 2 h of age, decreased significantly at 12 h of age [12.2 ± 2.1 cm versus 9.6 ± 1.7 cm (p < 0.001) and 8.0 ±1.1 versus 7.1 ± 1.4 (p < 0.01), respectively] but remained constant thereafter. Although no significant changes in flow velocity-time integral of atrial contraction and peak velocity of atrial contraction were noted during the first 24 h of birth, the flow velocity-time integral of early diastolic filling and peak velocity of early diastolic filling that were high at 2 h of age were reduced significantly at 12 h of age [5.0 ± 0.9 cm versus 4.1 ± 1.1 cm (p < 0.005) and 60.9 ± 9.0 cm/s versus 50.3 ± 9.0 cm/s (p < 0.001), respectively], resulting in significant reductions in the ratio of flow velocity-time integral of early diastolic filling/flow velocity-time integral of atrial contraction and the ratio of peak velocity of early diastolic filling/peak velocity of atrial contraction at 12 h of age. The size of the ductus arteriosus was found to be correlated with the peak velocity of early diastolic filling (r = 0.42, p < 0.05). Our results clearly demonstrate that the pattern of early diastolic filling was dependent on preload, whereas that of late diastolic filling was independent of preload in the early neonatal period. © 1994 International Pediatric Research Foundation, Inc.