[Comparative study on the ultrastructures of radial and internal mammary arteries used for coronary artery bypass grafting].
OBJECTIVE
The radial artery differs from internal mammary artery in its vascular biology and long-term patency after coronary artery bypass grafting (CABG). This study was designed to investigate their ultrastructural differences that may have implications in arterial remodeling and graft failure.


METHODS
Thirty-four radial artery and 11 internal mammary artery samples were obtained from patients underwent CABG, and subjected to routine electron microscopic examination. A semi-quantitative method was used to evaluate secretary endothelial cells, endothelial denudation, synthetic smooth muscle cells (SMCs), matrix accumulation, lipid deposition and medial submicroscopic calcification.


RESULTS
Compared with internal mammary arteries, the radial arteries had more secretory endothelial cells (47.1%, 16/34 vs 27.2%, 3/ 11) and synthetic type SMCs in a background (14.4% vs 0.9%) that had more intimal lipid deposition and matrix accumulation (14.7%, 5/34 vs 9.1%, 1/11). Matrix vesicles and calcifications were frequently present in the media of both types of arteries. The calcifications, however, could not be visualized by routine histological stains, and therefore, named as submicroscopic calcification in this study. Fewer endothelial denudations were observed in the radial arteries, but no differences in medial lipid deposition and submicroscopic calcification were observed between these two types of arteries. The ultrastructural features and the arrangement of medial SMCs in radial arteries were similar to those of internal mammary arteries.


CONCLUSIONS
Radial arteries have a higher SMC proliferative potential and more actively secretory status of endothelial cells, which may enhance the remodeling process and correlate with a decreased long-term patency. Better preservation of endothelial cells in radial arteries could be attributed to the "no touch" technique utilized in surgical harvesting. The significance of submicroscopic medial calcification during graft remodeling requires further investigations.
Wang
Hong-Yue
HY
Department of Pathology, Cardiovascular Institute & Fuwai Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100037, China. hywangs@hotmail.com
Meng
Ying
Y
Lou
Xin-Jin
XJ
Chu
Yan
Y
Xu
Xin-Lin
XL
Sun
Han-Song
HS
Ruan
Ying-Mao
YM
D002114:Calcinosis; D001026:Coronary Artery Bypass / Q000379:methods*; D003327:Coronary Disease / Q000473:pathology / Q000601:surgery*; D042783:Endothelial Cells / Q000473:pathology / Q000648:ultrastructure; D006801:Humans; D008297:Male; D008323:Mammary Arteries / Q000637:transplantation / Q000648:ultrastructure*; D008854:Microscopy, Electron; D008875:Middle Aged; D032389:Myocytes, Smooth Muscle / Q000473:pathology / Q000648:ultrastructure; D017534:Radial Artery / Q000637:transplantation / Q000648:ultrastructure*; D017539:Tunica Intima / Q000473:pathology / Q000648:ultrastructure