CHANGES IN RIGHT-VENTRICULAR VOLUME IN EARLY HUMAN NEONATES

To evaluate changes in the right ventricular volume in early human neo nates, twenty fullterm infants were examined at 2, 24 and 120 h of age by two-dimensional echocardiography. End-diastolic and end-systolic r ight ventricular volumes (RVEDV and RVESV, respectively) were calculat ed with a computer system based on the bi-plane Simpson's rule using t he apical four chamber and parasternal short axis views. Then right ve ntricular stroke volume (RVSV), ejection fraction (RVEF), and the mean normalized systolic ejection rate were obtained. The inner diameter o f the ductus arteriosus was also measured simultaneously. RVEDV increa sed significantly by 24 h of age, but remained constant thereafter. RV ESV remained virtually unchanged from 2 to 120 h, resulting in a signi ficant increase (36%) of RVSV at 24 h compared with that at 2 h. The m ean normalized systolic ejection rate remained unchanged. There was a good correlation between RVEDV and RVSV (r = 0.83). All ductus arterio sus except three narrow ones was closed by 24 h of age. In conclusion, at 24 h of age, the significantly increased RVEDV was closely related to the increased RVSV, which might be induced by increased volume loa d to the right ventricle because of the closure of the ductus arterios us. (C) 1997 Elsevier Science Ireland Ltd.