Modeling of the Effects of Aortic Valve Stenosis and Arterial System Afterload on Left Ventricular Hypertrophy

Abstract

Ventricular hypertrophy is an important adaptive mechanism that occurs in disorders associated with pressure or volume overload of the left ventricle. Hypertrophy of the cardiac muscle is defined as an increase in the size of existing myocardial fibers (15). The pressure-overload—induced hypertrophy, which is usually observed in valvular, subvalvular, or supravalvular aortic stenosis and in arterial hypertension, would cause concentric hypertrophy. In this case, the increase in left ventricular mass is associated with a normal-sized left ventricular internal cavity and is characterized by an increase in the ventricular wall thickness-to-diameter ratio. The severity of aortic valve stenosis is assumed to reflect the degree of left ventricular hypertrophy, while increased blood pressure also compounds this process. There are many studies attempting to correlate the left ventricular mass and wall thickness to blood pressure andJor the Gorlin formula derived valve area. However, because of associated confounding factors, the role that the arterial system plays when coexisting with aortic valve stenosis remains unclear. In this chapter, we present an interactive model that affords examinations of the individual effect of blood pressure and aortic valve in the development of a hypertrophic ventricle, as well as the combined effects of coexisting aortic valve stenosis and hypertension, that is, when a stenotic aortic valve and hypertension impose a double load on the left ventricle.