Inhaled Nitric Oxide in the Preoperative Evaluation of Pulmonary Hypertension in Heart Transplant Candidates

Abstract

The goal of this study was to evaluate the efficacy of 100% oxygen and inhaled nitric oxide (iNO) in decreasing pulmonary vascular resistance (PVR) and transpulmonary gradient (TPG) in dilated cardiomyopathy patients being evaluated for orthotopic heart transplantation (OHT); who, despite maximal intravenous (IV) dilator therapy, had persistent moderate-to-severe pulmonary hypertension. A prospective nonrandomized clinical study. University hospital, major transplant center. Twenty-one adult patients undergoing OHT evaluation. One hundred percent oxygen and iNO at 20 and 40 ppm were sequentially administered to the patients once they were optimized with IV vasodilators and inotropes. Although no significant change was noted with oxygen, iNO 20 ppm reduced the mean pulmonary artery pressure (44.1 +/- 1.7 to 38.6 +/- 1.8 mmHg, p < 0.05), PVR index (823 +/- 47 to 621 +/- 55 dyne/s/m(2)/cm(5), p < 0.05), TPG (22.4 +/- 1.4 to 17.0 +/- 1.5 mmHg, p < 0.05), and right ventricular stroke work index (14.7 +/- 1.2 to 11.1 +/- 1.2 g . m/m(2)/beat, p < 0.05). In 13 of 21 patients, PVR decreased by greater than 25% after iNO therapy. Nine of these patients had PVR and TPG decrease to levels considered acceptable for OHT listing. iNO can further improve right ventricular hemodynamics even after presumed optimization with IV vasodilators and serves as a test of PVR reversibility during the preoperative assessment of OHT candidates.