Factors associated with post-operative myocardial ischaemia in elderly patients undergoing major non-cardiac surgery

Forty patients (> 65 years) undergoing hip arthroplasty or peripheral vascu lar surgery both associated with high risk for post-operative myocardial is chaemia were randomized to receive either spinal or general anaesthesia. Am bulatory ECG recording (Holter) until the third post-operative morning, a d aily 12-lead ECG and serum creatine kinase and troponine concentrations wer e obtained. The number of ischaemic episodes, total duration of ischaemia a nd ischaemic minutes per hour were noted for each patient peri-operatively. Sixteen of the patients (40%) had post-operative myocardial ischaemia. An intra-operative increasein the plasma concentration of norepinephrine but n ot epinephrine was detectedin the patients who later developed post-operati ve myocardial ischaemia. The increase in plasma norepinephrine concentratio ns correlated with the decrease in core temperature. The type of anaesthesi a had no effect on the incidence of myocardial ischaemia during or after su rgery. Our results suggests that intra-operatively decreased core temperatu re and the increase in plasma concentration of norepinephrine probably caus ed peripheral vasoconstriction leading to latent cardiac dysfunction. These events should be avoided in the patients at risk of post-operative cardiac ischaemia.