Longitudinal evaluation of myocardial function in preterm infants with respiratory distress syndrome

Abstract

Preterm births and respiratory distress syndrome (RDS) are associated with pulmonary vascular disease and altered myocardial function. We serially assessed up to 1year of age the effects of RDS on global and regional myocardial function of preterm infants, compared to preterm and term controls using conventional echocardiography parameters, tissue Doppler velocities and deformation analysis. A total of 120 infants (30 preterm [PT] with RDS, 30 PT controls without RDS, and 60 term controls) underwent conventional and tissue Doppler echocardiography within 72hours of birth, at corrected term age for the preterm infants, at 1month corrected, and at 1year corrected age. At birth, compared to preterm and term controls, the PT-RDS group had decreased right ventricular (RV) long-axis function, systolic velocity, peak systolic strain, shorter pulmonary arterial acceleration time (PAAT), and lower ratio of PAAT to RV ejection time (PAAT:RVET). Preterm infants had left ventricular (LV) diastolic dysfunction at birth (lower early diastolic myocardial velocity, mitral E velocity, and mitral E:A ratio), and reduced long-axis systolic velocities and shortening. Differences between groups disappeared by 1month corrected age, except PAAT:RVET which remained lower in the PT-RDS group. At 1year, RV function was normal in PT-RDS apart from systolic strain rate, and LV function was normal apart from lower stroke volume and shortening, relative to body weight. PT-RDS had lower left and right ventricular systolic and diastolic function at birth which improved over time, suggesting postnatal maturation of cardiac function and resolution of lung disease.