Angiographic anatomy of the grafted left internal mammary artery

Background. The hypothesis that persistence of undivided branches is a comm on finding after myocardial revascularization using the left internal mamma ry artery was explored. Methods. Three hundred seven consecutive postoperative angiographies of the left internal mammary artery were considered. Seven were excluded because of occlusion or malfunction of the conduit or the anastomosis. Of the remai ning 300, 150 were harvested through a left anterior small thoracotomy (gro up A) and 150 through a median sternotomy (group B). The persistence of und ivided branches was recorded for each group. Results. Common origin with other branches of the subclavian artery was pre sent in 55 patients in group A and 54 in group B (p = not significant); the persistence of lateral costal branch was also equally distributed in both groups (15 and 17; p = not significant). The first intercostal artery was p resent in 55 patients in group A and in none in group B (p = not significan t). Branches of 1 mm or more were more frequent in group A (34 versus 4, p < 0.001), as well as branches of less than 1 mm (140 versus 67;p < 0.001). Only 2 patients in group A had no branches versus 48 patients in group B (p < 0.001). Conclusions. Common origin with other branches of the subclavian artery and persistence of the lateral costal branch are common aspects in the angiogr aphic anatomy of the grafted left internal mammary artery. Moreover, new br anches, sometimes wider than 1 mm, develop with time. These findings are in dependent from the harvesting technique, the left anterior small thoracotom y, or the median sternotomy. If flow competition between the coronary and n oncoronary territories was a reality, coronary artery grafting with the lef t internal mammary artery would be unsuccessful since the beginning. (C) 19 99 by The Society of Thoracic Surgeons.