[Risk factors in postoperative myocardial infarction]

Myocardial infarction after major surgery occurred 25 times in 214 patients who had previously sustained infarcts. Analysis of data obtained before, during and after 335 operations in these patients revealed the following pathogenetic factors in the infarction: (1) The patient with the highest coronary risk had arterial hypertension of at least 160/95 mmHg and advanced arteriosclerosis combined with coronary arterial, peripheral arterial, cerebrovascular, and renovascular disease. (2) Myocardial necrosis occurred when oxygen supply was reduced, as evidenced from a fall in systolic blood pressure to 70 mmHg or less during operation or anaemia (RBC smaller than or equal to 3,5 times 10-6/mul) early after operation. (3) Risk of infarction was highest during the early postoperative stress period with elevated plasma catecholamine levels and thus an increased myocardial oxygen demand.