Effect of nitroglycerin in patients with increased pulmonary vascular resistance undergoing cardiac transplantation

Acute right ventricular failure due to persistent pulmonary hypertension is a risk factor for premature death after cardiac transplantation. The purpose of this study was to follow changes in pulmonary haemodynamics in patients with pulmonary hypertension undergoing heart transplantation, and to examine whether postoperative changes can be predicted from a preoperative nitroglycerin (NTG) challenge. Seventeen consecutive patients with NYHA class IV heart failure and pulmonary hypertension (pulmonal vascular resistance (PVR) > 2.5 Wood units) underwent an NTG infusion before cardiac transplantation and were followed up using measurements of pulmonary haemodynamics before, early (24 h) and late (6 months) after cardiac transplantation. The effect of NTG was measured preoperatively and compared with posttransplantation values. Postoperative (24 h) PVR was reduced in all patients when compared with preoperative findings (PVR from 4.1 +/- 0.2 to 1.9 +/- 0.2 Wood units, Mean +/- SEM, p < 0.05). Mean pulmonary artery pressure (mPAP) was lowered in 16 of out 17 patients (41 +/- 2 to 26 +/- 1 mmHg, p < 0.05). None of the parameters were significantly changed during the subsequent 6 months. Postoperative PVR and mPAP were accurately estimated by preoperative NTG infusion (NTG vs 24 h posttranspl: PVR 2.2 +/- 0.2 vs 1.9 +/- 0.2 Wood units, p > 0.05; mPAP 30 +/- 2 vs 26 +/- 1 mmHg, p > 0.05). Heart transplantation candidates with pulmonary hypertension responsive to NTG can be expected to obtain a postoperative immediate fall in pulmonary pressures and PVR. The magnitude of this circulatory improvement can be predicted from a preoperative NTG infusion and is not different from values measured 6 months after transplantation.