Tissue Doppler velocity during early diastole (e') is one of the most feasible and reproducible echocardiographic assessments to reflect active relaxation of the left ventricle. Although several reports have described the mechanisms of temporal diastolic dysfunction in the early neonatal period, factors influencing diastolic function have not been determined. The purpose of this study was to elucidate factors significantly influencing e' in the early neonatal period.

A total of 179 consecutive normal neonates underwent echocardiographic studies performed at 0 days and 5-10 days after birth. The statistical relationships between e' and age, body weight, mean blood pressure, heart rate, shortening fraction of the left ventricle, peak systolic motion velocity (s'), early diastolic transmitral flow velocity over annulus velocity, Tei index, and diastolic wall strain (DWS) were analyzed.

Between the 0 days and 5-10-days-after birth groups, significant differences were shown in mean blood pressure, shortening fraction of left ventricle, e', and Tei index. Age, body weight, mean blood pressure, s', and DWS showed significant correlations with e'. In multivariate regression analysis within these parameters, s' (β = 0.6119, P < 0.0001) and DWS (β = 0.1216, P = 0.0321) showed positive correlations with e'.

Longitudinal systolic motion velocity and ventricular wall stiffness of the left ventricle influence diastolic relaxation in normal neonates. Age, body weight, and circumferential systolic function are not significant factors.