Coronary Artery Disease

CORONARY ARTERY DISEASE

A 65-year-old man with hypertension, familial hyper-cholesterolemia, type II diabetes mellitus, and angina pectoris presents for resection of a tumor of the sigmoid colon. A dipyridamole-thallium scan demonstrates an anteroseptal perfusion defect, which shows filling on the delayed image. Coronary angiography demonstrates a critical lesion of the left anterior descending coronary artery and a 50% stenosis of the proximal circumflex coronary artery. Percutaneous transluminal coronary angioplasty (PTCA) was performed successfully on the left anterior descending lesion 6 weeks prior to surgery.

General anesthesia is induced with etomidate, midazolam, and fentanyl, and maintained with oxygen, isoflurane, and fentanyl. Muscle relaxation is provided with vecuronium. During mobilization of the tumor, the heart rate increases from 70 to 120 beats per minute. The blood pressure remains stable at 130/70 mmHg. Two millimeters of hori-zontal ST-segment depression are noted on the V₅ electro-cardiogram (ECG) lead, but no abnormality is seen in lead II. An additional dose of fentanyl is associated with a decrease in the heart rate to 95 beats per minute, but no change in the ST-segment depression in V₅.