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.
Julius
S
S
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor.
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology* / Q000627:therapeutic use; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans
D000959:Antihypertensive Agents