Pathology of stent implantation in internal mammary artery
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The internal mammary artery (IMA) is the most durable conduit for bypassing the left anterior descending (LAD) coronary artery in patients undergoing coronary artery bypass graft surgery (CABG). However, little is known about how the IMA reacts histologically to stent implantation. From CVPath stent registry (1048 lesions, 614 cases), we obtained 4 stent lesions (2 bare metal stents, 2 drug-eluting stents) involving IMA grafts. The mean age of our patients was 63 years and the duration of stent implantation in the IMA ranged from 5 days to 5 years. Stented arteries were dissected from hearts and embedded in plastic, segmented at 3 mm intervals, sectioned at 4–6 microns and stained with H&E and Movat pentachrome stains. Histological observations were performed. Majority of stents (3 of 4) were implanted in anastomosis between IMA and LAD while 1 stent was implanted in IMA body. One stent with duration of 5 days showed stent thrombosis while others were all patent with fully coverage by varying degrees of neointima. Foamy macrophage, lipid pool and calcification in neointima were observed in 1 stent with duration of 5 years but it was limited only to the distal LAD part within the stented segment. Overall, in this small pathologic series, the majorities of stents were implanted in IMA-to-LAD anastomosis site and demonstrated acceptable pathologic responses.
KeywordsCoronary artery bypass graft Internal mammary artery Graft failure Stent Anastomosis
We thank Talbot Mayo and David Kamerow for the support.
Compliance with ethical standards
The study was sponsored by CVPath Institute, a non-profit organization dedicated cardiovascular research. There was no industry involvement in the design, conduct, financial support, or analysis of this study.
Conflict of interest
CVPath Institute has research Grants from Abbott Vascular, Atrium Medical, Boston Scientific, Biosensors International, Cordis-Johnson&Johnson, Medtronic CardioVascular, OrbusNeich Medical and Terumo Corporation. H. M has received honorarium from Abbott Vascular Japan, Goodman and Terumo Corporation. S. T has received honorarium from Abbott Vascular Japan, Terumo Corporation and SUNRISE lab. R. V has speaking engagements with Merck; receives honoraria from Abbott Vascular, Boston Scientific, Lutonix, Medtronic and Terumo Corporation and is a consultant for 480 Biomedical, Abbott Vascular, Medtronic and W. L. Gore. A. V. Finn has sponsored research agreements with Boston Scientific and Medtronic CardioVascular and is an advisory board member to Medtronic CardioVascular. The other authors report no conflict.
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