Angiographic Follow-up of Internal Thoracic Artery for Free Bypass Grafting

Background. The use of free internal thoracic artery (ITA) grafts in patients with smaller body surface areas has been questioned because of technical difficulties and inadequate graft flow. Methods. To evaluate postoperative changes in the diameter of free ITA grafts, we performed coronary angiography immediately after coronary artery bypass grafting and then again at a mean of 42 ± 6 months later. In 20 consecutively treated patients, 21 free ITAs were used as bypass conduits. Two ITA grafts that were patent at the time of the first angiography had closed at the second angiography. Postoperative changes in ITA graft diameter were measured in the 19 patent ITA grafts. Results. At the first angiography, the mean diameters of the proximal, middle, and distal ITA grafts were 2.28 ± 0.45 mm, 2.34 ± 0.39 mm, and 2.12 ± 0.38 mm, respectively. At the second angiography, the mean diameters of the proximal, middle, and distal ITA grafts were 2.85 ± 0.50 mm, 2.89 ± 0.53 mm, and 2.72 ± 0.53 mm, respectively. All segments of the ITA grafts had dilated significantly between the first and second angiographic evaluations (p < 0.01). The percentage change in graft diameter was greater when the initial ITA diameter was less than 2.3 mm (32.0% ± 28.0%) than when it was 2.3 mm or more (18.8% ± 11.3%) (p < 0.05). Conclusions. The postoperative increase in free ITA graft diameter depends on coronary blood flow requirements.