The use of vasodilator therapy in chronic AR and MR may be beneficial in selected patients and harmful in others. The hemodynamics of the two conditions are different and must be taken into account. In AR, vasodilators reduce afterload mismatch and can preserve LV function and delay the need for surgery. However, if the patient has severely reduced diastolic blood pressure, vasodilators could potentially impair coronary perfusion. In MR, vasodilators may reduce regurgitant volume and LV preload depending on the mechanism of MR. In patients with MR caused by dilated cardiomyopathy, vasodilators reduce symptoms, and improve functional class. However, in mitral valve prolapse or hypertrophic cardiomyopathy, vasodilators may worsen the MR and should be avoided. In other primary causes of MR, vasodilators could potentially mask the development of LV dysfunction and lead to unnecessary and harmful delays in surgery.