Effects of Pulmonary Insufficiency on Biventricular Function in the Developing Heart of Growing Swine

Abstract

Background— This study was conducted to determine the effects of chronic pulmonary insufficiency (PI) on right (RV) and left (LV) ventricular function in young growing swine. Methods and Results— Six PI and 5 control animals were studied. PI was induced by transcatheter placement of stents across the pulmonary valve. Indices of systolic function (ejection fraction, cardiac output, and cardiac functional reserve), diastolic function (compliance), and myocardial contractility (the slope of the relationship of end-systolic pressure versus end-systolic volume [E max ] and the slope of the dP/dt max –end-diastolic volume relationship [M dP/dt ]) were assessed within 2 days of intervention and 3 months later. MRI was used to quantify PI and ventricular volumes. Conductance catheter techniques were used to obtain indices of contractility and diastolic compliance from pressure-volume relations at rest and under dobutamine infusion. In the PI group, pulmonary regurgitant fraction was 49.2±5.9% at 3-month follow-up. RV cardiac functional reserve was limited, diastolic function was preserved, and myocardial contractility was altered (E max =2.6±0.3 mm Hg/mL for the PI group versus 3.5±0.4 mm Hg/mL for control; P <0.01). LV cardiac functional reserve was limited, ventricular compliance decreased, and myocardial contractility was preserved. Conclusions— In the young developing heart, chronic PI alters biventricular systolic function, RV myocardial contractility, and LV diastolic performance.