Conference: 2018 PHA International PH Conference & Scientific Sessions
Release Date: 07.28.2018
Presentation Type: Abstracts
File Download: Conference 2018_1034
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Abstract presented at the 2018 International PH Conference and Scientific Sessions in Orlando, Fla., June 28-July 1, 2018.
Preterm birth, or less than 37 weeks completed gestation, affects one in 10 live births in the United States. While lung disease is the most frequently recognized complication of prematurity, adults born moderately to extremely preterm have a 3-fold increased risk for the development of pulmonary vascular disease and a 17-fold increased risk for heart failure. The right ventricle (RV) is disproportionately affected, with decreases in RV but not left ventricular (LV) ejection fraction in early adulthood identified in a prior single-center study. Here, we sought to characterize pulmonary vascular and RV function in young adults born premature.
Adults born preterm (n=11; gestational age 28.2±0.8 weeks; current age 27±1 years) were recruited from the Newborn Lung Project at the University of Wisconsin-Madison, a prospective cohort of infants born 1988-1991 with birth weight <1500 g. Controls were recruited from the general population (n=10; age 26±1 years). All subjects were free from adult cardiopulmonary disease. Subjects underwent right heart catheterization with measurement of pulmonary vascular hemodynamics and cardiac magnetic resonance imaging (MRI) on a 3.0T scanner. Cardiac MR measures included assessment of RV function and RV circumferential strain. 4D flow imaging was acquired with a radially-undersampled PC VIPR sequence to assess RV kinetic energy, and RV energetic efficiency was defined as total kinetic energy across the cardiac cycle normalized to stroke volume. Mann-Whitney tests were performed to assess for statistical significance (p<0.05).
Young adults born premature had mild elevations in mean pulmonary artery pressure and total pulmonary vascular resistance. Resting RV stroke volume, stroke volume index, and ejection fraction were similar between preterm and term subjects. However, cardiac output and cardiac index were significantly higher among preterm subjects secondary to a higher resting heart rate. RV strain analysis demonstrated increased peak RV circumferential strain among preterm subjects, suggesting a hypercontractile myocardium. When stroke volume was divided by peak RV circumferential strain as a measure of RV efficiency, preterm subjects exhibited reduced RV efficiency. 4D flow analysis also demonstrated a decreased RV energetic efficiency, requiring a higher kinetic energy for a given stroke volume.
Otherwise healthy young adults born premature demonstrate mild elevations in pulmonary pressures and vascular resistance, though most fall below current cut points for treatment of pulmonary vascular disease. In addition, they have a hypercontractile, energetically inefficient RV, which may provide mechanistic insight into the increased risk for heart failure in this population. Whether they will require earlier treatment of pulmonary vascular disease in order to maintain RV function warrants further study.