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 mmHg 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.