The purpose of this study was to determine in term newborn infants the effects of ductus arteriosus on ventricular performance and its determinants: preload, afterload and contractility.

Sixteen term neonates were considered suitable for our study. Gestational age and body weight ranged 38-42 weeks (mean 39.4 weeks), 2.89-4.04 (mean 3.4 kg). Heart rate, ductus arteriosus (PDA)size , left ventricular end diastolic volume (LVEDV), left ventricular end systolic volume (LVESV), Ejection fraction (EF), mean normalized systolic ejection rate (mNSER), systolic and diastolic pressure, total vascular resistance, left ventricular stroke volume (SV), LA/aorta ratio were measured noninvasively in 16 healthy term infants at 5 predefined time intervals from 2 hours 120 hours. LV volume was calculated by the biplanar Simpson's rule, and the ductus arteriosus size with left to right shunting was measured by two dimensional and Doppler echocardiography.

At 2 hours, the ductus arteriosus was at its maximal size, and the LV end-diastolic volume was higher than at the subsequent hours after birth. A good association between PDA size and LVEDV was found.

These result suggest that alteration in the LVEDV soon after birth depend on changes in ductal flow, which in turn in affected by ductal size.