Abstract 180

Treatment of pulmonary hypertensive crises in patients undergoing reconstructive cardiac surgery is both empirical and difficult. The advent of inhaled nitric oxide (iNO) for use in these patients appears to offer a useful additional therapy, but its benefit may be dependent upon the specific underlying disorder. We report our cumulative experience with iNO, based on the type of congenital heart disease. In the four year period 1995 through 1998, 62 patients undergoing reconstructive surgical procedures were treated with inhaled nitric oxide. iNO was begun at 20 ppm either intraoperatively or within less than 8 hours postoperatively for management of pulmonary hypertensive crises diagnosed either clinically or by combination of pulmonary vascular and oxygen-hemoglobin saturation monitoring. Duration of treatment was from 1 to 10 days. A total of 20 patients (32%) expired, 17 within the acute period after the surgery and 3 of non-cardiac organ failure weeks to months later. Eight of the 62 patients had undergone reconstructive procedures for hypoplastic left heart syndrome. There were 5 survivors to discharge from this group. A total of 15 patients were treated for hypertensive crises with the underlying diagnosis of pulmonary overflow from either ventricular septal defect of endocardial cushion defect. All survived. Thirteen of these 15 patients responded to inhaled nitric oxide; 2 of the 15 did not respond and required treatment with reinstitution of extracorporeal membrane oxygenation. There were 16 infants with obstructed right ventricular outflow tracts with pre-operative diminished pulmonary blood flow; there were 3 deaths. Six patients comprised one category for whom inhaled nitric oxide may be contraindicated preoperatively: those with obstructed anomalous pulmonary venous return. Three of the 6 survived. Other categories included truncus arteriosus, type 1 (n=3 with 1 survivor), aortic valve disease (n=2, with 1 survivor), others (n=12). No complications such as elevated NO2 levels or systemic hypotension were detected. There were no apparent clinically distinguishing features between the 42 survivors and the 20 non-survivors by age, gender, or acid-base status at the time of surgery. Our data support the contention that inhaled nitric oxide is an effective adjunctive treatment for perioperative pulmonary hypertensive crises and provide a rationale for longer term use of this agent. As it is unlikely that definitive, stratified, prospective, placebo-controlled, randomized, blinded studies will be performed using nitric oxide in this population of patients, because of the heterogenous nature of the physiology and local treatment preferences, it is important that the cumulative experience of phase II studies with inhaled NO be reported based on disease category.