Myocardial hypertrophy. Light microscopic findings on the myocardium. Blood supply. Ventricular dilatation and heart failure.

The heart is an organ with an almost constant number of muscle cells under physiological conditions. But beyond the critical heart weight (500 g) there is an increase in the number of muscle fibers (hyperplasia) and a similar increase in the number of capillaries. The relation of 1 capillary to 1 muscle fiber remains constant. During physiological growth there is a rather close correlation between the growth of human coronary arteries and the growth of the myocardium. Under pathological conditions the growth of coronary arteries is slower than that of the myocardium. In many animal species investigated up to now there is a rather close correlation between the diameter of coronary arteries and the diameter of the heart. As a rule, hearts with chronic insufficiency are dilated. They work under unfavourable geometrical conditions. The post-mortem ventricular volume is influenced to a very great degree by rigor mortis.