Differences in the Shape of the Normal, Cardiomyopathic, and Volume Overloaded Human Left Ventricle

Abstract

A transformation from the normal elliptical shape of the left ventricle that may accompany various disease states and that may be indicative of myocardial remodeling, has not been completely addressed in part because of the need for a descriptor of shape that is independent of chamber size. Accordingly, the goal of this study was twofold: to derive dimensionless echocardiographic descriptors of left ventricle chamber shape that are independent of chamber volume and to use these descriptors to quantitatively compare the shape of left ventricles that were either of normal size (81 ± 17 ml, 19 patients) or were enlarged secondary to idiopathic caridomyopathy, (194 ± 61 ml, 46 patients) or chronic aortic or mitral valve incompetence (196 ± 67 ml, 14 patients). Two-dimensional and M-mode determined descriptors, of left ventricle shape based on its width, length, and area were found to be independent of left ventricle volume. These descriptors were significantly greater in cardiomyopathy compared with the normal or dilated left ventricle secondary to valvular incompetence, indicating that the left ventricle had become nearly spherical. A spherical shape of the left ventricle was not observed with valvular incompetence. The ability to classify a patient as hawing either a normal or a cardiomyopathic left ventricle by discriminant function analysis was enhanced when both left ventricle size and shape were considered. In a prospective study using discriminant function and fractional shortening, we found that patients with valvular incompetence could be classified as having either a normal discriminant function and fractional shortening, an abnormal discriminant function and normal fractional shortening, or an abnormal discriminant function and fractional shortening. The clinical utility of this discriminant function analysis with descriptors of left ventricle shape and size in the prediction of myocardial remodeling needs to be determined.