ARTERIOSCLEROTIC HISTOLOGIC EVALUATION OF THE INTERNAL MAMMARY ARTERYIN PATIENTS UNDERGOING CORONARY-ARTERY BYPASS-GRAFTING

During 1991, 52 patients undergoing myocardial revascularization had a biopsy of the distal internal left mammary artery (IMA) taken. There were 48 male and 4 female patients with a medium age of 58 years. Ater iosclerotic involvement of the IMA was assessed according to the scale of Kay. Using this index, grade 0 corresponds to a normal artery with out atherosclerosis, grade 1 represents minimal disease, grade 2 a nar rowing of less than 25% of the lumen, grade 3 narrowing between 25 and 50%, and grade 4 narrowing of 50% or greater of the lumen. Of the 52 IMA examined, the arteries with degree 0, 1, 2, 3, and 4 were: 19 (36. 5%), 20 (38.4%), 9 (17.6%), 4 (7.6%) and zero. Thirty-three arteries ( 63.4%) had some degree of atherosclerosis. Considering the arteries wi th some atherosclerotic narrowing, 13 (25%) of the whole group had thi s pathological alteration. The IMA has a low but consistent incidence of arteriosclerosis involvement. Preoperative angiographic investigati on of the IMA could be routinely performed.