Pathological analysis of the radial and internal thoracic artery

To evaluate the usefulness of the radial artery (RA) as a graft material for coronary artery bypass grafting (CABG), histologic studies of the RA were performed and compared with the internal thoracic artery (ITA). Specimens were obtained from both ends of 12 RAs and the distal side of the ITA during the operation. The degree of arteriosclerosis was evaluated using an NIH Image 1.57 system. The pathological index of arterioslerotic change was expressed as the ratio of cross-section (Rx: internal luminal area/tunica media area). The mean arteriosclerotic ratio (Rx) of the 12 proximal sides of the RA specimens was 0.18 +/- 0.03, the 12 distal sides 0.27 +/- 0.17, and the 12 ITAs was 0.14 +/- 0.05, respectively. There was significant difference between the distal side of the RA and the ITA. The distal side of the RA was a little greater than the proximal, but there was no significant difference between the proximal side of the RA and the ITA. From the microscopic findings, the tunica media of the RA is poor in elastic fibers and rich in smooth muscle cells compared with the ITA. The internal elastic lumina of the RA is developed as well as the ITA, but more calcification was found in the distal RA than in the others. According to these results, although care must be taken for arteriosclerosis of the distal RA, it can be expected to be a suitable bypass material for CABG.