Limitations of right internal thoracic artery to left anterior descending artery bypass: a comparative quantitative study of postoperative angiography of the bilateral internal thoracic artery bypass grafts.

Background: It remains controversial whether right internal thoracic artery (RITA) to left anterior descending artery (LAD) bypass has qualitative limitations which cannot be evaluated based on the patency rate alone. Methods: The 111 subjects underwent graft angiography after bypass grafting of the left or right internal thoracic artery (ITA) to the LAD. The vascular caliber was measured at the origin of the ITA, at an ITA site adjacent to the anastomotic site, and at an LAD site immediately below the anastomotic site, regarding the outer diameter of the catheter as a reference. Results: The caliber of the ITA immediately above the anastomotic site of the LAD was significantly lower in the RITA group. In the left internal thoracic artery (LITA) group, no patient showed a caliber of less than 1.25 mm, but five patients (7.8%) did in the RITA group. The preoperative cardio-thoracic ratio was significantly higher than that in patients in whom the caliber of the ITA immediately above the anastomotic site was 1.25 mm or more, and the height was significantly lower. Conclusions: In many patients, the RITA is appropriate as a graft material to the LAD. However, in patients with a high cardio-thoracic ratio and those with a low height, the RITA may not reach the LAD in a favorable state, and the LITA should be anastomosed to the LAD in some patients.