Significance of new Q waves after bypass grafting: Correlations between graft patency, ventriculogram, and surgical venting technique

Abstract New Q waves were observed in 56 (8 per cent) of 671 patients undergoing saphenous vein bypass grafting, with an over-all mortality rate of 1.8 per cent. Forty-two of the 56 (75 per cent) had postoperative ventriculograms and arteriograms and are reported herein. Ventricular venting was used intraoperatively in 17 patients, and atrial venting in 25. Thirty-one patients had new “anterior” and/or “septal” Q waves, while 23 had “inferior” or “infero-lateral” and 2 had “lateral” Q waves. The incidence of new Q waves in patients with ventricular venting was 22 per cent and in those with atrial venting it was 5.8 per cent (p These findings indicate a poor correlation between new Q waves and graft closure. Improved postoperative ventriculograms correlated well with graft patency despite new Q waves. The etiology of new post-bypass graft Q waves are varied. They include direct ventricular trauma and conduction delays resulting from surgery or venting, as well as true ischemic infarction. Infarction may be due to compromised arterial inflow either in non-operated diseased vessels, in vessels distal to anastomoses with patent grafts, or due to graft closure.