Increased pulmonary arterial pressures after pentazocine in myocardial infarction

In 15 patients with acute myocardial infarction intravenous pentazocine in a dose of either 30 or 60 mg. was followed by a significant increase in mean pulmonary arterial pressure. In the group receiving the 60-mg. dose this change was associated with a significant increase in systemic arterial pressure, total peripheral resistance, and left ventricular minute work. Because of these circulatory effects intravenous pentazocine in a dose of 60 mg. would seem to be unsuitable for the relief of pain in myocardial infarction.