In dogs with pacing-induced heart failure, high end-diastolic pressures result from geometric remodeling altering chamber compliance rather than stiffer myocardium, preventing elastic recoil.
This study demonstrates that in pacing-induced heart failure, restrictive filling patterns result from geometric remodeling and loss of elastic recoil rather than intrinsic myocardial stiffening.
In patients with heart failure, decreased contractility resulting in high end-diastolic pressures and a restrictive pattern of left ventricular filling produces a decrease in early diastolic filling, suggesting a stiff ventricle. This study investigated the elastic properties of the myocardium and left ventricular chamber and the ability of the heart to utilize elastic recoil to facilitate filling during pacing-induced heart failure in the anesthetized dog. Elastic properties of the myocardium were determined by analyzing the myocardial stress-strain relation. Left ventricular chamber properties were determined by analyzing the pressure-volume relation using a logarithmic approach. Elastic recoil was characterized using a computer-controlled mitral valve occluder to prevent transmittral flow during diastole. We conclude that, during heart failure, the high end-diastolic pressures suggestive of a stiff ventricle are due not to stiffer myocardium but to a ventricle whose chamber compliance characteristics are changed due to geometric remodeling of the myocardium. The restrictive filling pattern is a result of the ventricle being forced to operate on the stiff portion of the diastolic pressure-volume relation to maintain cardiac output. Slowed relaxation and decreased contractility result in an inability of the heart to contract to an end-systolic volume below its diastolic equilibrium volume. Thus the left ventricle cannot utilize elastic recoil to facilitate filling during heart failure.
Solomon et al. (Sun,) conducted a other in Pacing-induced heart failure. Pacing-induced heart failure model was evaluated on Elastic properties of the myocardium and left ventricular chamber. In dogs with pacing-induced heart failure, high end-diastolic pressures result from geometric remodeling altering chamber compliance rather than stiffer myocardium, preventing elastic recoil.