Peripheral vasodilators

Vasodilators, as their name imply, treat hypertension by causing the smooth muscle walls of blood vessels to relax, thus dilating the vessel. The systemic peripheral vascular resistance (afterload) is reduced by dilating on the arterial side of the vascular system. The peripheral venous return (preload) is reduced by dilating the veins. The overall effect is a decrease in arterial blood pressure, an increase in ventricular output, and a decrease in end-diastolic volume. In hypovolemic states, vasodilators must be used with caution because they can worsen perfusion to vital organs. Most vasodilating medications to some degree work on both the arterial side and the venous side of the vascular system. However, some vasodilators work more specifically on one side or the other. These medications are used in a wide variety of disease states, such as coronary artery disease, heart failure, and hypertension. The effectiveness of vasodilator treatment for patients with chronic congestive heart failure has been demonstrated in large multicenter clinical trials (Vasodilator-Heart Failure Trial I and II). The combination of different vasodilators has been shown to significantly improve symptoms, exercise tolerance, and survival of heart failure patients.