A PATHOHISTOLOGICAL AND BIOCHEMICAL-STUDY OF ARTERIOSCLEROSIS IN THE INTERNAL THORACIC ARTERY, A VESSEL COMMONLY USED AS A GRAFT IN CORONARY-ARTERY BYPASS-SURGERY

Pathohistological and biochemical studies were conducted on the severi ty of arteriosclerosis in the internal thoracic artery (ITA), an arter y commonly used for coronary artery bypass grafting (CABG). For the pa thohistological examination, 26 bilateral ITAs and 13 left anterior de scending coronary arteries (LADs) obtained in full length from 13 auto psy cases, none of which had died of arteriosclerotic heart disease, w ere used. The ratio of the thickness of the intima to that of the medi a (R) was used as the index for arteriosclerosis. ITAs and LADs were c lassified as grades I to IV according to the value of R. The R of the ITAs was approximately 1/10 that of the LADs (P < 0.01). Most ITAs sho wed a low arteriosclerotic grade, with no variation in arteriosclerosi s along their length and a low R in all segments. No difference was fo und between right and left ITAs. Biochemical examination was conducted on 12 ITAs and 11 LADs, obtained from 12 different and unselected aut opsy cases. The lipid content in the vascular wall was determined to e valuate the severity of arteriosclerosis, with the following results: Total cholesterol, 5.5 +/- 1.8 and 17.8 +/- 13.6 mug/mg wet weight (P < 0.05); triglyceride, 90.4 +/-90.3 and 114.4 +/- 117.2 mug/mg wet wei ght (n.s.); and phospholipid, 7.4 +/- 3.9 and 11.2 +/- 3.9 mug/mg wet weight (P < 0.05), respectively, for the ITAs and LADs. These findings thus demonstrate that arteriosclerosis of the ITA in Japanese people is very mild, compared to that of the LAD in the same individuals.