Myocardial Ischemia during Non-cardiac Surgical Procedures in Patients with Coronary-artery Disease

Abstract

Graded to determine the incidence of ST-segment depression during anesthesia and operation, exercise testing demonstrated a high correlation between ST-segment depression and myocardial ischemia. 11 patients without, and 29 patients with, coronary-artery disease were monitored during surgical procedures with a commercially available exercise ECG monitor (Viagraph). Comparisons were made between this device, which monitored lead V5, and the standard operating room monitor, which monitored lead 11. Of 29 patients in the disease group, 11 demonstrated significant ST depression. Of the 11 ischemic episodes 9 were not recognized on the standard operating room monitor. Retrospective review of anesthetic records of those 11 patients with ST-segment depression revealed rate-pressure product values greater than 11,000 for 10. Postoperatively, 3 of the 11 patients with significant ST-segment depression had changing ECG compatible with ischemia. None of the control group demonstrated significant ST-segment depression. The incidence of ischemia was 38% during anesthesia and operation in the coronary artery disease group. Lead V5 analysis is superior to lead 11 analysis in detecting ST-segment depression. The period in which intubation is performed is one of the highest-risk intervals during anesthesia and operation, particularly when it is associated with an increased rate-pressure product.