Does inhaled nitric oxide improve survival in operated congenital disease with severe pulmonary hypertension?

BACKGROUND: The present study aimed to assess the impact of inhaled nitric oxide on survival following correction of congenital heart defects with residual pulmonary arterial hypertension. METHODS AND RESULTS: Inhaled nitric oxide was utilized for the management of residual pulmonary hypertension in 24 children following surgical correction of their underlying heart defects. Their ages ranged from 15 days to 14 months (median 5 months). Pulmonary artery hypertension was diagnosed either by direct pulmonary artery pressure monitoring or by echocardiography. Inhaled nitric oxide was used electively in 22 patients when the ratio of the mean pulmonary arterial pressure and mean systemic arterial pressure exceeded 0.5. In the remaining 2 patients, nitric oxide was used only to manage a pulmonary hypertensive crisis. Inhaled nitric oxide was also used a second time in 2 patients who developed delayed pulmonary hypertensive crisis. Twenty-two patients showed an initial response to therapy and the pulmonary artery pressures dropped significantly. Of the patients on direct pulmonary artery pressure monitoring, a pulmonary artery to systemic artery pressure ratio below 0.3 on prolonged therapy was associated with a survival ratio of 4/6 (including 1 neurological death and one reoperation); that between 0.3 and 0.5 with a survival ratio of 3/4. Three out of four patients with sustained echocardiographic and clinical response also survived and were discharged from the hospital. All the patients who showed a lack of response to (n=2), tolerance to (n=1), or dependence on (n=6) the use of inhaled nitric oxide died. In addition, all 5 patients who had a pulmonary hypertensive crisis died, 3 in spite of successful resuscitation with nitric oxide. Thus, excluding one neurological death and one re-operation, only 9 (41%) out of 22 patients survived. CONCLUSIONS: Though inhaled nitric oxide is effective in lowering pulmonary pressure, it does not appear to improve the survival rate following repair of congenital heart disease in those with associated severe pulmonary hypertension. A randomized trial between the use and non-use of inhaled nitric oxide is warranted to determine its exact role in influencing survival in patients with residual pulmonary hypertension following surgical repair.