Postural influences on the hemodynamic responses to vasodilating drugs in congestive heart failure.

Supine and upright hemodynamic measurements were performed in 58 patients with congestive heart failure to assess the effects of postural change on the hemodynamic responses to vasodilating drugs. The patient population was divided into three treatment groups and was studied before and after isosorbide dinitrate, nifedipine, or clonidine treatment. When the hemodynamic responses in the upright position were compared with the supine values, isosorbide dinitrate (40 mg orally) evoked a greater reduction in mean systemic blood pressure and stroke volume with augmented increases in heart rate, mean pulmonary artery pressure, and pulmonary vascular resistance while the patient was upright. Nifedipine (10 mg orally) when studied in the upright position caused additional augmentation of cardiac output and stroke volume index with further reduction in total systemic vascular resistance compared with supine values. No position-related changes in hemodynamic measurements were noted with clonidine (0.1 mg orally).