[Dependence of a drop in blood pressure in pulmonary circulation and in the right heart on dosage of isosorbide dinitrate].

An effect of isosorbide dinitrate on blood pressure values in the pulmonary circulation and the right heart has been investigated in 25 patients with a history of the first transmural myocardial infarction. Group I including 12 patients has been given 5 mg isosorbide nitrate in a 60-minute intravenous infusion while group II of 13 patients has been given 10 mg of the drug in the same way. Both groups have been matched in clinical data and blood pressure value in the pulmonary circulation which has been normal. Pulmonary blood pressure has been measured with Swan-Ganz catheter prior to the administration of drug, and 15, 30, 45 and 60 minutes following an infusion. Isosorbide dinitrate in a dose of 5 mg did not decrease blood pressure in the pulmonary circulation statistically significantly. The differences in blood pressure falls did exceed 9%. Filling pressure in the right ventricle did not change either while systolic blood pressure decrease by 16.6%. A double dose of isosorbide dinitrate reduced blood pressure in the pulmonary artery by about 1/3 of the baseline value, and blood pressure in the right ventricle (mean right atrial pressure) by 57.2%. Both systolic and diastolic arterial pressures were reduced. Isosorbide dinitrate reduced blood pressure in the pulmonary circulation in patients who underwent myocardial infarction, and hypotensive effect has been dose-related. A reduction in the right ventricular filling pressure has been a one of important mechanisms decreasing pulmonary pressures.