Effects of antihypertensive therapy on the hemodynamics of hypertension: clinical implications.

Early essential hypertension is characterized by high cardiac output and normal total peripheral resistance and renal blood flow; in chronic hypertension, total peripheral resistance is elevated, cardiac output is decreased from initial levels, and renal blood flow diminishes as the disease progresses. The various classes of antihypertensive drugs induce different hemodynamic effects to maintain blood pressure control. Long-term administration of all classes of antihypertensive drugs results in a decrease in mean arterial pressure, and most drugs reduce total peripheral resistance. Heart rate and cardiac output generally remain unchanged, but they are decreased after long-term therapy with beta-blockers. Some beta-blockers also reduce renal blood flow. Drugs such as the selective alpha 1-adrenergic blocking agent prazosin, which normalizes the hemodynamic profile of hypertension, appear to be advantageous. In addition, prazosin maintains exercise tolerance at near-normal levels.