[Changes in luminal diameter of internal thoracic arteries five years after coronary artery bypass grafting]

Five years after coronary artery bypass grafting, 23 internal thoracic arteries (ITAs) were reexamined angiographically, and their luminal diameters were compared with those of one month after the operation. Proximal diameter, just below the subclavian artery, and distal diameter, just above the anstomosis, were measured. One month after surgery, these were 2.38 +/- 0.48 mm and 1.69 +/- 0.39 mm, respectively. After five years, the proximal diameter had not changed significantly (2.48 +/- 0.47 mm), but the distal diameter had increased to 1.96 +/- 0.58 mm (p < 0.05). Especially when there was no competitive flow with the ITA, the distal diameter showed a marked increase from 1.80 +/- 0.35 mm to 2.27 +/- 0.42 mm (p < 0.01). Twelve ITAs were grafted to coronary arteries having less than critical stenosis, and five of them showed distal narrowing or so-called string sign after five years. This seemed to be a form or physiological atrophy resulting from competitive flow, and the patients had no anginal pain in spite of their poor ITA runoff. When coronary artery stenosis is less than 75%, a choice is difficult between an ITA or a saphenous vein graft. We think that the graft must be selected considering the possibility of stenosis progression, if the jeopardized area is important for the patient. An ITA graft would be advisable in such cases.