The effect of ventricular dilatation and hypertrophy on the performance of cardiac valves : a model study

While extensive studies have been performed on the physiology and Pathophysiology of ventricular dilatation (VD) and ventricular hypertrophy (VH) in recent years, the effect of the VD and VH on the dynamic performance of prosthetic heart valves (PHV) has not been reported. This thesis presents a study of the dynamic performance of ten clinical PHV in Doth mitral and aortic positions by using a normal ventricular model, in which the ventricular end- diastolic volume (EDV) decreases with increased heart rates, and three dilatation and hypertrophy models, in which each of them has a fixed EDV, i.e., the EDV does not vary with changed heart rates. The experimental mock circulation flow loop, to simulate the geometrical and dynamic characteristics of the natural left ventricle of an average adult human, consists of three basic components: a pulse duplicator, a valve testinq chamber, and an afterload simulator. Physiological pressure waveforms are rigorously required during each experimental run, by properly adjusting the afterload units. The heart rate varies from 120 to 60 beats per minute in steps of ten beats. The aortic pulse pressure is controlled at about 120/70 mm Hg throughout the experiment. The cardiac output varies within the range of 3 to 8 liters per minute. [...]