Coronary reserve in experimental myocardial hypertrophy

Three types of dysfunction of the coronary circulation have been described in experimental models of hypertension associated with left ventricular hypertrophy: (I) reduced coronary reserve, (2) a relative decrease in perfusion of subendocardial layers, (3) a shift to the right, i.e. to higher pressures, of the circulation pressure autoregulation range. These abnormalities are also observed in hypertensive patients, although it is significant that they do not appear to be related to the extent of left ventricular hypertrophy. The exact causes of these abnormalities have yet to be elucidated. Left ventricular hypertrophy does not seem to be an essential factor, although in certain experimental models of hypertension, there does appear to be a mismatch between the development of the coronary vasculature and hypertrophy of the myocytes. The stresses in vessels due to the increase in systolic, and especially intraventricular diastolic pressure can be viewed as additional aggravating factors. The essential abnormalities are structural and/or functional alterations in arterial walls. The structural alterations are reflected by a narrowed lumen due to parietal thickening. This may result from growth of muscle fibres (hypertrophy or hyperplasia) or collagen tissue and/or remodelling of tissues with no overall change in mass. Functionally, the reduced ability of the arteries to stretch, resulting from endothelial alterations may also play a role in the abnormalities observed in hypertensive patients. In our studies, we examined the effect of the antihypertensive drug perindopril on the coronary circulation in th