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

Objective: 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.Design: A prospective nonrandomized clinical study.Setting: University hospital, major transplant center.Participants: Twenty-one adult patients undergoing OHT evaluation.Interventions: 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.Measurements and Main Results: 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/m2/cm5, 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/m2/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.Conclusions: 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.