Significance of new Q waves after bypass grafting: correlations between graft patency, ventriculogram, and surgical venting technique.
New postoperative electrocardiographic Q waves have been described in eight of 40 per cent of patients undergoing bypass grafting for coronary artery disease. Various theories have been proposed to explain these new Q waves. Correlations of new Q waves to vein bypass occlusion, prolonged pump time or aortic cross-clamping time are controversial. Indeed, whether or not the appearance of new postoperative Q waves means real transmural myocardial infarction is not clear. We report herein our experience with postoperative Q waves in 56 patients with vein bypass grafts and the relationship of new Q waves to ventricular venting, graft patency, and the postoperative ventriculogram. Our observations indicate that: (1) Not all Q waves are due to occlusion of the saphenous bypass grafts (as noted by others). (2) A certain percentage of new Q waves may not reflect true transmural myocardial infarction, especially when all the vein grafts are patent and the postoperative ventriculograms show improvement. (3) Some new Q waves reflect true transmural infarction due to occlusion of grafts or of distal coronary arteries with deteriorated left ventriculograms. (4) The high incidence of new Q waves in patients with ventricular vents is probably due to direct myocardial trauma at the apex of the left ventricle.
D000328:Adult; D000368:Aged; D001026:Coronary Artery Bypass; D004562:Electrocardiography; D005260:Female; D006325:Heart Atria / Q000601:surgery; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011859:Radiography