VASODILATOR THERAPY AFTER HEART-TRANSPLANTATION - EFFECTS OF INHALED NITRIC-OXIDE AND INTRAVENOUS PROSTACYCLIN, PROSTAGLANDIN E(1), AND SODIUM-NITROPRUSSIDE

Background: Vasodilator therapy is frequently needed to treat pulmonar y hypertension after heart transplantation. In the present study, the effects of intravenous sodium nitroprusside, prostacyclin, prostagland in E(1), and inhaled nitric oxide (5, 19, and 20 parts per million) on central hemodynamics, right ventricular function, and pulmonary selec tivity were evaluated shortly after heart transplantation. Methods: He modynamic measurements were made after surgery in the intensive care u nit. The intravenous vasodilators were compared at equipotent infusion rates. Effects of inhaled nitric oxide were measured after 10 minutes inhalation at each dose level. Results: Cardiac output, stroke volume , right ventricular end-diastolic volume, and central filling pressure s were highest with prostacyclin (16 +/- 2 ng/kg/min) compared with bo th prostaglandin E(1) (202 +/- 27 ng/kg/min) and sodium nitroprusside (1.0 +/- 0.2 mu g/kg/min). Systemic and pulmonary vascular resistance were lowest with prostacyclin. None of the intravenous vasodilators in duced a selective pulmonary vasodilation. In contrast, nitric oxide in halation induced a selective decrease in pulmonary vascular resistance , with no change in systemic vascular resistance. Cardiac output incre ased with nitric oxide, whereas mean pulmonary arterial pressure, tran spulmonary pressure gradient, and central venous pressure decreased, w ith the most pronounced effect at an inhaled concentration of 20 parts per million. Conclusions: Prostacyclin is the best choice for intrave nous vasodilator therapy after heart transplantation. However, inhaled nitric oxide is the only selective pulmonary vasodilator, which shoul d be used in cases of pulmonary hypertension and severe right ventricu lar failure associated with systemic hypotension.