Regression of cardiac hypertrophy. Experimental animal model.
Regression of cardiac hypertrophy has been proven to occur in experimental animals following some types of antihypertensive therapy. However, no direct and necessary correlation can be found between hypertension and cardiac hypertrophy. The effect of different antihypertensive drugs on regression of cardiac hypertrophy varies despite the same degree of reduction in arterial pressure in hypertensive control subjects. Therapy with alpha-methyldopa resulted in reversal of hypertrophy with effective blood pressure control, whereas treatment with vasodilators, namely hydralazine and minoxidil, either did not alter (hydralazine) degree of myocardial hypertrophy or increase it (minoxidil) despite normalization of blood pressure. The biochemical profile of the myocardium after regression of hypertrophy following antihypertensive therapy is not homogeneous; for example, reversal with alpha-methyldopa is associated with increased collagen content, whereas reversal with Captopril did not alter collagen content of the heart. Adrenergic factors seem to play an important role in the modulation of myocardial structure to variations in arterial pressure. Furthermore, in each type of hypertrophy in hypertension, a combination of different factors might be responsible, and it may not be correct to assume that the same factors must be involved in the regression of all types of myocardial hypertrophy.