title: Retaining perivascular tissue of human saphenous vein grafts protects against surgical and distension-induced damage and preserves endothelial nitric oxide synthase and nitric oxide synthase activity.
abstract: OBJECTIVE
  Conventional harvesting of saphenous vein used for coronary artery bypass surgery induces a vasospasm that is overcome by high-pressure distension. Saphenous vein harvested with its cushion of perivascular tissue by a "no touch" technique does not undergo vasospasm and distension is not required, leading to an improved graft patency. The aim of this study is to investigate the effect of surgical damage and high-pressure distension on endothelial integrity and endothelial nitric oxide synthase expression and activity in saphenous vein harvested with and without perivascular tissue.
  
  
  METHODS
  Saphenous veins from patients (n = 26) undergoing coronary artery bypass surgery were prepared with and without perivascular tissue. We analyzed the effect of 300 mm Hg distension on morphology and endothelial nitric oxide synthase/nitric oxide synthase activity using a combination of immunohistochemistry, Western blot analysis, reverse transcriptase polymerase chain reaction, and enzyme assay in distended (with and without perivascular tissue) compared with nondistended (with and without perivascular tissue) segments.
  
  
  RESULTS
  Distension induced substantial damage to the luminal endothelium (assessed by CD31 staining) and vessel wall. Endothelial nitric oxide synthase expression and activity were significantly reduced by high-pressure distension and removal of, or damage to, perivascular tissue. The effect of distension was significantly less for those with perivascular tissue than for those without perivascular tissue in most cases.
  
  
  CONCLUSIONS
  The success of the saphenous vein used as a bypass graft is affected by surgical trauma and distension. Veins removed with minimal damage exhibit increased patency rates. We show that retention of perivascular tissue on saphenous vein prepared for coronary artery bypass surgery by the "no touch" technique protects against distension-induced damage, preserves vessel morphology, and maintains endothelial nitric oxide synthase/nitric oxide synthase activity.
authors.affiliation: Department of Clinical Biochemistry, Royal Free and University College Medical School, Royal Free Campus, Pond Street, London, United Kingdom. m.dashwood@medsch.ucl.ac.uk
authors.forename: Michael R
authors.initials: MR
authors.lastname: Dashwood
authors.forename: Kay
authors.initials: K
authors.lastname: Savage
authors.forename: Janice C S
authors.initials: JC
authors.lastname: Tsui
authors.forename: Audrey
authors.initials: A
authors.lastname: Dooley
authors.forename: Sidney G
authors.initials: SG
authors.lastname: Shaw
authors.forename: Maria S
authors.initials: MS
authors.lastname: Fernández Alfonso
authors.forename: Lennart
authors.initials: L
authors.lastname: Bodin
authors.forename: Domingos S R
authors.initials: DS
authors.lastname: Souza
mesh_terms: D000328:Adult; D000368:Aged; D001026:Coronary Artery Bypass; D004108:Dilatation, Pathologic; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D012501:Saphenous Vein / Q000201:enzymology* / Q000378:metabolism / Q000502:physiology / Q000637:transplantation*; D020858:Tissue and Organ Harvesting / Q000379:methods*
chemical_list: D019408:Platelet Endothelial Cell Adhesion Molecule-1; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III