Left atrial strain assessment unveils left ventricular diastolic dysfunction in neonates with transient tachypnea of the newborn: A prospective observational study

Introduction: An inadequate clearance of lung fluid plays a key role in the pathogenesis of transient tachypnea of the newborn (TTN). Objectives: To evaluate if left ventricular diastolic dysfunction contributes to reduced clearance of lung fluid in TTN. Materials and Methods: This was a prospective, observational study. Echocardiography and lung ultrasound were performed at 2, 24 and 48 h of life (HoL) to assess biventricular function and calculate lung ultrasound score (LUS). Left atrial strain reservoir (LASr) provided surrogate measurement of left ventricular diastolic function. Results: Twenty-seven neonates with TTN were compared with 27 controls with no difference in gestation (36.1 +/- 2 vs. 36.9 +/- 2 weeks) or birthweight (2508 +/- 667 vs. 2718 +/- 590 g). Biventricular systolic function was normal in both groups. LASr was significantly lower in cases at 2 (21.0 +/- 2.7 vs. 38.1 +/- 4.4; p < 0.01), 24 (25.2 +/- 4.5 vs. 40.6 +/- 4.0; p < 0.01) and 48 HoL (36.5 +/- 5.8 and 41.6 +/- 5.2; p < 0.01), resulting in a significant group by time interaction (p < 0.001), after adjusting for LUS and gestational diabetes. A logistic regression model including LUS, birth weight and gestational diabetes as covariates, showed that LASr at 2 HoL was a predictor of respiratory support at 24 HoL, with an adjusted odds ratio of 0.60 (CI 0.36-0.99). Conclusions: LASr was reduced in neonates with TTN, suggesting diastolic dysfunction, that may contribute to the delay in lung fluid clearance.