A serial Doppler echocardigraphic study of early diastolic right ventricular events in full term neonates

Our purpose was to study serially, measurements which relate to right ventricular events, using echocardiography and Doppler in full term neonates for the first three weeks after birth. Echocardiographic and pulsed Doppler studies were performed for 21 newborns during the first 36 hours of life, and subsequent serial studies were performed in the second (n=21) and third (n=14) weeks of life. Evaluation included measurement of right isovolumic relaxation time and peak E and A velocities across the tricuspid valve. Pulmonary velocities were studied for evidence of patency of the arterial duct, and to determine acceleration in the pulmonary trunk. Mean right isovolumic relaxation time decreased significantly from 68±9 ms to 39 ± 14 ms (p<0.001) between the first and second week. Mean tricuspid peak E increased significantly between the second (48 ± 7 cm/s) and the third week of life (62 ± 8 cm/s; p<0.001). Mean peak A wave velocity did not change significantly during the time of study. The pulmonary arterial acceleration time increased from the initial measurement (68 ± 10 ms) to the second week (85 ± 9 ms; p<0.001). Changes in right isovolumic relaxation time were significantly related to the changes in the pulmonary arterial acceleration time (r=0.63, p=0.0001), suggesting a significant influence of afterload on diastolic events. These data demonstrate the normal progression of some measures of early right ventricular diastolic function.