Inhaled prostacyclin, nitric oxide, and nitroprusside in pulmonary hypertension after mitral valve replacement

Pulmonary hypertension increases morbidity and mortality in patients undergoing heart surgery. Mitral valve stenosis is frequently associated with an increase in pulmonary vascular resistance (PVR). Cardiopulmonary bypass exacerbates pulmonary hypertension in patients undergoing cardiac surgery. The aim of this study was to compare the hemodynamic effects of inhaled prostacyclin and nitric oxide and the administration of i.v. nitroprusside during cardiac surgery with a clinical, pharmacodynamic dose-response, prospective, randomized, and double-blind study (Group A: inhaled prostacyclin; Group B: inhaled nitric oxide; Group C: nitroprusside).

Fifty-eight patients with mitral valve stenosis and elevated PVR (>200 dynes sec/cm5) after mitral valve surgery were studied. Inhaled prostacyclin and nitric oxide were administered at concentrations of 10 g/min and 20 ppm, respectively. Nitroprusside i.v. was administered at the dose of 5-15 g/min.

Prostacyclin and nitric oxide produced a significant dose-related decrease of mean pulmonary arterial pressure, pulmonary vascular resistance, and transpulmonary gradient. A significant increase in cardiac output was observed in both groups. In Group C, nitroprusside administration was interrupted in 62% patients due to occurrence of systemic hypotension.

Inhaled prostacyclin and nitric oxide are effective in the treatment of postoperative pulmonary hypertension in patients with mitral valve stenosis undergoing mitral valve surgery. Both drugs improve cardiac output and reduce mean pulmonary arterial pressure, pulmonary vascular resistance, and trans-pulmonary gradient. They may be useful in patients with acute right ventricular failure following cardiac surgery. In comparison to nitric oxide, inhaled prostacyclin is free from toxic side effects and is easier to administer.