Experimental heart hypertrophy and failure. Morphological aspects.

Abstract

Several types of heart overloading experimentally induced in rabbits and rats were morphologically compared. Myocardial cell dimensions were most often harmoniously increased (length increasing in the same proportion than length). Increase in cell volume was more pronounced in subendocardial layers than in midwall and subepicardium. In adult animals comparison between heart weight and cell dimensions were indicating of a process of pure hypertrophy. In heart hypertrophy induced in young rats by sideropenic anemia the same comparison suggested a double process of hypertrophy and hyperplasia. At the ultrastructural level modifications encountered early after the load induction such as: decrease in condensed chromatin, multiplication and enlargement of nucleoli, enlargement of Golgi apparatus and r.e.r., increase in number and decrease in size of mitochondria may be interpreted as cytological features of cell overactivity. L tubulus were most often well preserved. Disorganization of myofibrils and intercalated discs, seemed to be due to some cellular damage. Cell overactivity and damage were found not only in the early stages of overloading, but also several months later. Heart failure was often associated with large foci of cell damage in the subendocardium.