Background: The hypothesis that persistence of undivided branches is a common finding after myocardial revascularization using the left internal mammary 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 remaining 300, 150 were harvested through a left anterior small thoracotomy (group A) and 150 through a median sternotomy (group B). The persistence of undivided branches was recorded for each group.
Results: Common origin with other branches of the subclavian artery was present 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 present in 5 patients in group A and in none in group B (p = not significant). 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 angiographic anatomy of the grafted left internal mammary artery. Moreover, new branches, sometimes wider than 1 mm, develop with time. These findings are independent from the harvesting technique, the left anterior small thoracotomy, or the median sternotomy. If flow competition between the coronary and noncoronary territories was a reality, coronary artery grafting with the left internal mammary artery would be unsuccessful since the beginning.