Pressure control during preparation of saphenous veins.
OBJECTIVE
Long-term patency of human saphenous veins (HSVs) used as autologous conduits for coronary artery bypass grafting (CABG) procedures remains limited because of vein graft failure (VGF). Vein graft failure has been reported to be as high as 45% at 12 to 18 months after surgery and leads to additional surgery, myocardial infarction, recurrent angina, and death. Preparation of HSVs before implantation leads to conduit injury, which may promote VGF.


OBJECTIVE
To investigate whether pressure distension during vein graft preparation leads to endothelial injury and intimal thickening and whether limiting intraluminal pressure during pressure distension by using a pressure release valve (PRV) preserves endothelial function and prevents neointima thickening.


METHODS
Segments of HSVs were collected in a university hospital from 13 patients undergoing CABG procedures immediately after harvest (unmanipulated [UM]), after pressure distension (after distension [AD]), and after typical intraoperative surgical graft preparation (after manipulation [AM]). Porcine saphenous veins (PSVs) from 7 healthy research animals were subjected to manual pressure distension with or without an in-line PRV that prevents pressures of 140 mm Hg or greater. Endothelial function of the HSVs and PSVs was determined in a muscle bath, endothelial integrity was assessed, and intimal thickening in PSVs was evaluated after 14 days in organ culture.


METHODS
Endothelial function was measured in force, converted to stress, and defined as the percentage relaxation of maximal phenylephrine-induced contraction. Endothelial integrity was assessed by immunohistologic examination. Neointimal thickness was measured by histomorphometric analysis.


RESULTS
Pressure distension of HSVs led to decreased mean (SEM) endothelial-dependent relaxation (5.3% [2.3%] for AD patients vs 13.7% [2.5%] for UM patients; P < .05) and denudation. In the AM group, the function of the conduits was further decreased (-3.2% [3.2%]; P < .05). Distension of the PSVs led to reduced endothelial-dependent relaxation (7.6% [4.4%] vs 61.9% [10.2%] in the control group; P < .05), denudation, and enhanced intimal thickening (15.0 [1.4] µm vs 2.2 [0.8] µm in the control group; P < .05). Distension with the PRV preserved endothelial-dependent relaxation (50.3% [9.6%]; P = .32 vs control), prevented denudation, and reduced intimal thickening (3.4 [0.8] µm; P = .56 vs controls) in PSVs.


CONCLUSIONS
Use of a PRV during graft preparation limits intraluminal pressure generated by manual distension, preserves endothelial integrity, and reduces intimal hyperplasia. Integration of this simple device may contribute to improved long-term vein graft patency.
General Hospital of Jinan Military District, Jinan, China.
Fan Dong
FD
Li
Division of Cardiothoracic Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee.
Susan
S
Eagle
Division of Vascular Surgery, Vanderbilt University Medical Center, Nashville, Tennessee.
Colleen
C
Brophy
Division of Vascular Surgery, Vanderbilt University Medical Center, Nashville, Tennessee.
Kyle M
KM
Hocking
Division of Vascular Surgery, Vanderbilt University Medical Center, Nashville, Tennessee.
Michael
M
Osgood
Division of Vascular Surgery, Vanderbilt University Medical Center, Nashville, Tennessee.
Padmini
P
Komalavilas
Division of Vascular Surgery, Vanderbilt University Medical Center, Nashville, Tennessee.
Joyce
J
Cheung-Flynn
D000818:Animals; D001696:Biomechanical Phenomena; D001026:Coronary Artery Bypass / Q000379:methods*; D004730:Endothelium, Vascular / Q000293:injuries / Q000503:physiopathology*; D006801:Humans; D007124:Immunoenzyme Techniques; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology*; D009924:Organ Culture Techniques; D011312:Pressure / Q000009:adverse effects*; D012189:Retrospective Studies; D012501:Saphenous Vein / Q000293:injuries / Q000473:pathology* / Q000637:transplantation*; D013552:Swine; D013997:Time Factors; D014661:Vasoconstriction / Q000502:physiology