Experimental and Clinical Studies in Cardiac Hypertrophy

That the diseased heart is usually larger than the normal organ was noted more than 300 years ago. Subsequent observation showed that the increase in muscle mass occurred mainly in that part of the heart placed under a mechanical handicap as a result of the lesion, and, with the obvious analogy of skeletal muscle hypertrophy as a result of increased activity, the hypertrophy of heart muscle was ascribed to the increased work necessary to overcome the mechanical defect. The theory of work hypertrophy has had almost universal acceptance. Stewart, 1 in a study of the relative weights of the different chambers of the heart associated with experimental aortic regurgitation in dogs, found that while the left ventricle hypertrophied more than other chambers, the right ventricle and auricles showed some increase in muscle mass. This he ascribed, however, to increased work of these chambers, probably the result of an intracardiac reflex,