PULMONARY VASCULAR EFFECTS OF NITROGLYCERIN AND ISOSORBIDE DINITRATE IN PATIENTS WITH END-STAGE CARDIOMYOPATHIES

Background: Severe preoperative pulmonary hypertension predicts a poor outcome after heart transplantation and therefore pulmonary vasoreact ivity is frequently evaluated in the pretransplantation screening. Amo ng the i.v. organic nitrates used in this evaluation, isosorbide dinit rate and nitroglycerin differ in their pharmacokinetics, and isosorbid e dinitrate has been suggested to be more selective in its effects on pulmonary vasculature than nitroglycerin. Methods: Haemodynamic effect s of nitroglycerin and isosorbide dinitrate were compared in 8 patient s with end-stage cardiomyopathy. Each patient was given increasing i.v . infusion-doses of the two nitrates in a random order and double-blin d and cross-over fashion until the target of at least 25% decrease in mean pulmonary artery pressure was achieved. Results: A total dose of 11 (3-20) (mean, 95% confidence interval) mu g kg(-1) of nitroglycerin and that of 87 (12-161) mu g kg(-1) of isosorbide dinitrate were give n during the infusions of 20 (14-27) and 28 (18-37) min duration, resp ectively. With these doses producing similar acute decreases in mean p ulmonary artery pressure, both nitroglycerin and isosorbide dinitrate also showed equal effects on pulmonary and systemic vascular resistanc es as well as on other systemic and right ventricular haemodynamic par ameters. Conclusion: We conclude that there is no difference between i .v. nitroglycerin and isosorbide dinitrate in their selectivity on the pulmonary vasculature in patients with end-stage cardiomyopathy.