The finer intramyocardial vasculature in various forms of experimental cardiac hypertrophy.

The finer intramyocardial vascular architecture in various forms of cardiac hypertrophy was studied by a combined stereomicro-angiographic and histological procedure. Significant cardiac hypertrophy was induced by renal hypertension, aortic stenosis and swimming exercise. The training-induced hypertrophy was reversible. The myocardial vascular architecture was altered in cardiac hypertrophy. There were essential differences in the vascular patterns of training-induced hypertrophy, on one hand, and hypertrophy secondary to hypertension and aortic stenosis, on the other. The nature of these differences suggested that training-induced hypertrophy was associated with neoformation of vessels in an otherwise structurally unaltered myocardial vasculature, while the other forms of hypertrophy were dominated by a transformation of the preformed vascular pattern. In the regression of hypertrophy, which took place during the resting period after training, only minor changes appeared in the myocardial vascular pattern.