# Evaluation of Biventricular Diastolic Function in Preterm Infants in the First Week of Postnatal Life

## TL;DR

This study tracks how the heart's relaxation function improves in preterm infants during their first week of life and finds that a condition called PDA is linked to worse heart function.

## Contribution

The study provides new insights into biventricular diastolic function evolution and its association with hemodynamically significant PDA in preterm infants.

## Key findings

- Mitral E/e′ and lateral e′ velocities indicate improved diastolic relaxation in preterm infants by day 7.
- Infants with hemodynamically significant PDA show elevated left atrial pressure and impaired relaxation.
- Larger PFO diameter trends with lower left atrial volume indices, though not statistically significant.

## 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.

The online version contains supplementary material available at 10.1007/s00246-025-03974-7.