Controlled study of intravenous nitroglycerin treatment for two days in patients with recent myocardial infarction.

Hemodynamic measurements were obtained for 48 h in 46 patients with recent myocardial infarction. Patients were randomized to treatment with (n = 22) and without nitroglycerin (NTG) n = 24). In patients with diastolic pulmonary arterial pressure (PAEDP) less than 20 mmHg (group I), NTG decreased PAEDP from 15 to 11 mmHg (n = 13); in the untreated control group PAEDP remained unchanged (n = 15). Cardiac output decreased in the NTG group from 5.4 to 5.0 1/min and in the control group from 4.7 to 4.4 1/min. Mean arterial pressure decreased in both groups, in the NTG group from 106 to 97 mmHg and in the control group from 102 to 94 mmHg. In patients with left ventricular failure and PAEDP greater than 20 mmHg (group II) the decrease in left ventricular filling pressure was significantly greater (25 to 17 mmHg, n = 9) than in the control group (24 to 20 mmHg, n = 9). Cardiac output increased during NTG treatment from 4.2 to 5.1 1/min. In the control group, however, cardiac output decreased from 4.2 to 3.6 1/min. Mean arterial pressure decreased from 103 to 95 mmHg in the NTG group and from 114 to 96 mmHg in the control group. Heart rate did not change significantly. Thus, PAEDP decreased significantly in patients who received NTG treatment for 48 h compared to an untreated control group. Cardiac output increased in treated patients, especially those with left ventricular failure, but decreased in the control group. Mean arterial pressure decreased to the same degree in treated patients and in controls.