291 Myocardial Protection in Reoperative Coronary Artery Bypass Grafting: Toward Decreasing Morbidity and Mortality Shafie Fazel, M.D., M.Sc., Michael A. Borger, M.D., Ph.D., Richard D. Weisel, M.D., Gideon Cohen, M.D., Ph.D., Marc P. Pelletier, M.D., M.Sc., Vivek Rao, M.D., Ph.D., and Terrence M. Yau, M.D., M.Sc. Toronto General Hospital and Sunnybrook and Women’s Health Sciences Centre, Affiliated with the University of Toronto, Ontario, Canada ABSTRACT Redo coronary artery bypass grafting (CABG) is associated with higher morbidity and mortality when compared to first-time CABG. Myocardial infarction and dysfunction contribute significantly to the increased risk of redo CABG. Results of reoperative coronary surgery have gradually improved, largely because of improvements in myocardial protection techniques. In the present review we will highlight the principles of myocardial protection in redo CABG patients with an emphasis on retrograde cardioplegia. (J Card Surg 2004;19:291-295) According to the Society of Thoracic Surgeon’s database, redo coronary artery bypass grafting (CABG) comprises 8% of the total CABG cases. The morbid- ity and mortality of redo CABG are significantly higher than first-time CABG, but continue to gradually de- crease. 1-7 The major hurdles to the completion of an uncomplicated redo CABG operation are fourfold: (i) in- creased risk of massive hemorrhage during redo ster- notomy, 8-10 (ii) injury to patent grafts, 11,12 (iii) emboliza- tion of atheromatous debris caused by manipulation of diseased bypass grafts, 13 and (iv) inadequate cardio- plegia delivery. 14 The increased atherosclerotic burden also increases the likelihood of systemic atheroem- bolization and increased risk of associated complica- tions such as cerebrovascular accidents. Although redo CABG patients have presented with increasing comorbidities over the years, the results of reoperation have gradually improved. 2,7,15 The current review will expand on the principles of myocardial pro- tection that are pertinent to redo coronary bypass oper- ations, particularly because these principles have had a significant beneficial effect on redo CABG outcomes. NATURAL HISTORY OF BYPASS GRAFTS Fitzgibbon and colleagues 16 recently summarized their 25-year observation of saphenous vein grafts (SVG). Ten years after surgery, 337 of 856 (40%) SVGs examined by angiography were occluded, 400 (46%) were diseased, and only 119 (14%) appeared to be Address for correspondence: Michael A. Borger, Division of Car- diac Surgery, Toronto General Hospital, EN 13-217, 200 Elizabeth Street, Toronto, Ontario, M5G-2C4. Fax: 416-340-3803; e-mail: Michael.borger@uhn.on.ca disease-free (Fig. 1). In the diseased but patent cate- gory, 222 grafts (56%) had one or more irregularities >50% of estimated intimal surface. After 15 years, 10% of grafts remained patent and free of disease. In many instances the progression of SVG disease within the context of a symptomatic patient had mandated reintervention. It is important to note the observations of Marshall and colleagues 17 that the pathologic exami- nation of angiographically disease-free SVG at the time of reoperation frequently revealed significantly more disease than anticipated (Fig. 2). SVG failure, therefore, is common, its incidence increases exponentially with time, and its extent is underestimated by clinical symp- toms and angiography. MYOCARDIAL PROTECTION— 1. RETROGRADE CARDIOPLEGIA In a series of 1500 coronary reoperations at the Cleveland Clinic, 18 most deaths (74%) were related to myocardial dysfunction. In a recent review of our ex- perience at the Toronto General Hospital, Yau et al. 7 compared the outcome of first-time CABG with redo CABG and found that the incidence of perioperative myocardial infarctions (3.7% vs. 7.4%), low-output syn- drome (9.0% vs. 24.0%), and death (2.4% vs. 6.8%) were significantly increased in patients undergoing reoperation. Inability to adequately protect the heart during redo CABG stems from two major factors. First, old SVG atheromatous disease may embolize into the coro- nary circulation. Keon and colleagues 13 performed an autopsy series and reported a 2.3% incidence of fa- tal myocardial infarction caused by distal emboliza- tion of atheromatous material from old SVG. Second,