Delayed chronic type A dissection following CABG: Implications for evolving techniques of revascularization

Background: Postoperative dissection in some patients is related to manipul ation of the aorta and accounts for 3% to 5% of deaths after cardiac surger y. Methods: Between 1987 and 1999, 109 patients with previous cardiac opera tions were treated for chronic type A dissection. In 31 of the patients, th e etiology was related to aortic manipulation. Twenty-one patients (17 men, 4 women; 67 +/- 13 years of age) had isolated coronary artery bypass graft ing (CABG) as their first operation and were reviewed. The interval between operations was 52.9 +/- 47.3 months. Results: Reoperation was elective in 11 patients, urgent in 10 patients. Median maximal aortic diameter was 6.8 +/-2.1 cm; 9 patients had major aortic insufficiency. The intimal tear was at the partial occlusion clamp site in 12 patients (57.1%), at the cross-cl amping site in 4 patients (19.1%), and at the proximal anastomosis in 1 pat ient (4.8%); 4 patients (19.1%) had multiple tears at several sites. Cystic media necrosis was present in 9.5% of the patients, severe atherosclerosis in 47.6% of the patients, and 42.9% of the patients had both. Nine patient s (42.9%) underwent a modified Bentall procedure, 12 patients (57.1%) under went a supracoronary anastomosis, and all had open distal anastomosis. Ther e were two (9.5%) hospital deaths and three (14.3%) postoperative strokes. Freedom from cardiac or aorta-related mortality was 85.7% at a mean follow- up of 49.3 months. Conclusions: In patients who develop type A dissection o f the aorta after previous CABG, the intimal tear most often is at partial occlusion clamp site. This complication is associated with morbidity and mo rtality. It remains to be seen whether the use of partial occlusion clamps on the pulsating and often diseased aorta during off-pump coronary artery b ypass (OPCAB) will increase the risk of delayed iatrogenic dissections.