[Prevention of per-operative myocardial ischemia with continuous nitroglycerin infusion]

The aim of this work is to assess the possible beneficial effects of intra and post operative nitroglycerin infusion in patients with disabling angina pectoris (Class III of the New-York Heart Association). We thus compared the occurrence of myocardial ischemia detected by means of continuous electrocardiographic recording of lead V5 in 31 patients which were divided in two groups. The control group (I) included 16 patients, group II included 15 patients undergoing similar surgical procedures, given a permanent nitroglycerin infusion. Mean dose of nitroglycerin was 0,91 +/- 0,18 micrograms . kg-1 . min-1. An ischemic type S T segment depression occurred in 15 out 16 patients in group I and in only 3 out of 15 patients in group II (p less than 0,001). No S T segment depression occurred following a decrease of more than 25 p. 100 in systolic blood pressure in 8 patients of group II at the time of induction. These hypotensive episodes were easily corrected by decrease of the nitroglycerin infusion rate associated with a rapid blood volume expansion. The very high incidence of intra operative myocardial ischemia in control group demonstrates the severity of the coronary disease in the observed patients. The significantly lower frequency of ischemic S T segment depression observed in the patients given nitroglycerin infusion suggests that this drug is highly effective in preventive myocardial ischemia in patients with severe coronary artery disease. The administration of nitroglycerin in our patients had been easy to control, blood pressure reaching normal value within a few minutes after decrease of the rate of drug infusion when needed.