ARE DIFFERENT HEMODYNAMIC PATTERNS OF ANTIHYPERTENSIVE DRUGS CLINICALLY IMPORTANT

Since vascular resistance is elevated in hypertension, it is suggested that vasodilators lower the blood pressure by a physiologic mechanism and therefore must be more useful than cardiac output-lowering drugs. This is not entirely correct. Drugs that lower cardiac output are also relative vasodilators, but the vasodilation occurs at a lower level of cardiac output. It is also not necessarily true that all vasodilators are good antihypertensive agents. The clinical profile of a vasodilator depends on its effect on the venous return, cardiac output, regional blood flow, renin-angiotensin system, and sympathetic reflexes. From the viewpoint of hemodynamics, an ideal antihypertensive drug is a vasodilator that does not excessively increase cardiac output, causes no fluid retention, does not induce a great deal of venodilation, and does not elicit substantial neurohumoral counterregulation. Angiotensin-converting-enzyme inhibitors, some calcium antagonists, and some combined alpha/beta-blocking agents come close to satisfying the hemodynamic definition of an ideal antihypertensive drug. © 1990 Springer-Verlag.