title: Competitive flow arising from varying degrees of coronary artery stenosis affects the blood flow and the production of nitric oxide and endothelin in the internal mammary artery graft.
abstract: OBJECTIVE
  Internal mammary arteries graft failure in coronary artery bypass grafting (CABG) is mostly considered to be a result of competitive flow (CF) from the native coronary artery, which significantly limits future revascularization options.
  
  
  METHODS
  With the left internal mammary artery (LIMA) anastomosed to the left anterior descending (LAD) coronary artery using an off-pump technique, CABG was performed on 15 Chinese swine. Then we produced varying degrees of stenosis in the proximal LAD coronary artery with an adjustable flow occluder, measured the mean flow of the LIMA and LAD coronary artery and detected the plasma concentrations of nitric oxide (NO) and endothelin (ET) in the LIMA graft.
  
  
  RESULTS
  When stenosis of the proximal LAD artery was decreased, the CF of the native LAD coronary artery showed an increasing trend, while the mean flow of the LIMA revealed a decreasing trend. Distal LAD coronary artery flow remained nearly constant, despite the varying proximal LAD artery or LIMA flow rates. An oscillating flow pattern (retrograde/antegrade) was noted in the LIMA graft when the proximal LAD coronary artery was not fully occluded. The plasma concentration of ET in the LIMA graft was significantly higher than that before grafting (P < 0.05), and the plasma concentration of NO was significantly lower (P < 0.05). The concentration of NO was positively related to the mean flow in the LIMA (r = 0.872, P < 0.05).
  
  
  CONCLUSIONS
  CF from the native LAD coronary artery can decrease the blood flow in the LIMA graft and even change the direction of the flow. These changes may impair the function of the LIMA graft and affect ET or NO production, which in turn may lead to early LIMA graft failure.
authors.affiliation: Department of Cardiovascular Surgery, Qilu Hospital of Shandong University, Jinan, China.
authors.forename: XiangBin
authors.initials: X
authors.lastname: Meng
authors.forename: Qiang
authors.initials: Q
authors.lastname: Fu
authors.forename: WenYu
authors.initials: W
authors.lastname: Sun
authors.forename: JianMin
authors.initials: J
authors.lastname: Yu
authors.forename: WeiMing
authors.initials: W
authors.lastname: Yue
authors.forename: YanWen
authors.initials: Y
authors.lastname: Bi
mesh_terms: D000818:Animals; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000097:blood* / Q000503:physiopathology; D004195:Disease Models, Animal; D016232:Endothelins / Q000097:blood*; D007387:Internal Mammary-Coronary Artery Anastomosis; D008323:Mammary Arteries / Q000378:metabolism / Q000503:physiopathology*; D009569:Nitric Oxide / Q000097:blood*; D012044:Regression Analysis; D013552:Swine
chemical_list: D016232:Endothelins; D009569:Nitric Oxide