NITRIC-OXIDE AND PROSTACYCLIN LOWER SUPRASYSTEMIC PULMONARY-HYPERTENSION AFTER CARDIOPULMONARY BYPASS

In a 3-week-old male newborn persistent suprasystemic pulmonary hypertension developed after surgical valvulotomy for a critical aortic valve stenosis. Because of a residual transvalvular pressure gradient of 35 mm Hg and postoperative left as well as right ventricular dysfunction, treatment with inhaled nitric oxide (NO) and intravenously infused prostacyclin (PGI2) was attempted. Low-dose inhaled NO and low dose PGI2 corrected severe pulmonary hypertension and led to an increase in cardiac output. Treatment with NO but not PGI2 was accompanied by a rise in PaO2 and systemic blood pressure. Interruption of NO administration led to a rapid increase in pulmonary arterial pressure to suprasystemic levels. With continued i.v. PGI2 and decreasing concentrations of NO, severe pulmonary hypertension resolved after a few days suggesting that a transient endothelial dysfunction was partially responsible for pulmonary vasoconstriction. NO inhalation appears to be an effective new tool in the treatment of severe pulmonary hypertension following cardiac surgery.