Cardiovascular adjustment to antiadrenergic agents.

A common target organ involvement associated with essential hypertension is left ventricular hypertrophy. A number of, but not all, effective antihypertensive drugs will regress left ventricular hypertrophy. Our attention has focused on the hemodynamic characteristics of those drugs that either directly or indirectly alter sympathetic nervous activity. alpha-Methyldopa has been widely studied in both experimental animals and hypertensive man and been found to be efficacious in lowering arterial pressure and regressing left ventricular hypertrophy. Another centrally acting antihypertensive drug, clonidine, produces similar hemodynamic effects but has no effect on left ventricular hypertrophy at similar hypotensive levels. Vasodilators such as hydralazine and minoxidil reflexly stimulate the sympathetic nervous system and may actually exacerbate left ventricular hypertrophy when given alone. In combination with beta adrenergic blocking agents, however, a reduction in both arterial pressure and cardiac mass may occur. Prolonged treatment with these antihypertensive agents had no detrimental effect on regional blood flows including myocardial flow. Ventricular performance studies indicate that regression of hypertrophy improves ventricular performance although the heart with regressed hypertrophy, when faced with an increased afterload, may still demonstrate impaired performance.