Abstract
Diastolic dysfunction contributes significantly to respiratory instability in preterm infants but remains under-characterized during early postnatal transition. We aimed to evaluate the evolution of biventricular diastolic function during the first week of life in very low birth weight (VLBW) preterm infants. In this prospective observational study, 20 preterm infants (< 32 weeks gestation or < 1500 g) underwent serial echocardiograms at 24, 48, 72 h, and day 7. TDI mitral/tricuspid inflow velocities, left atrial (LA) volume, cardiac output, and shunt characteristics were measured. Hemodynamically significant PDA (hsPDA) was defined by standard echocardiographic criteria. Mitral E/e' decreased from 16.4 [14.2-18.3] on day 1 to 13.1 [11.3-15.1] by day 7 (p < 0.01), while lateral e' increased from 3.3 [2.9-3.7] to 4.1 [3.6-4.6] cm/s (p = 0.009), consistent with improving relaxation. At day 7, infants with hsPDA (6/20) had higher mitral E/A ratios (1.08 [1.01-1.14] vs. 0.95 [0.89-1.00], p = 0.04), elevated E/e' (9.1 [8.4-10.0] vs. 6.4 [5.7-7.1], p < 0.01). Indexed LA volume was also larger in the hsPDA group. Larger PFO diameter (≥ 2.5 mm) showed a trend toward lower LA volume indices and E/e', although differences were not statistically significant. Rapid diastolic adaptation occurs during the first postnatal week in VLBW infants. hsPDA is linked to increased LA pressure and impaired relaxation. Early functional echocardiography may aid in guiding targeted neonatal care.