The Journal of Thoracic and Cardiovascular Surgery, Vol 102, 448-453, Copyright © 1991 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Atherogenic effect of barotrauma on in situ saphenous veins in monkeys
LE Boerboom, GN Olinger, ER Rodriguez, VJ Ferrans and AH Kissebah
Department of Cardiothoracic Surgery, Medical College of Wisconsin, Milwaukee.
The objectives of this study were to determine whether veins subjected to
barotrauma in situ undergo lipid uptake and morphologic changes to the same
extent as veins grafted into the arterial circulation. Saphenous veins in
seven stump-tailed macaque monkeys were exposed bilaterally and were
circumferentially dissected free from surrounding tissue only at isolated
sites. Segments of the veins were distended for 1 minute at hydrostatic
pressures of 125 or 350 mm Hg. An undistended segment served as control. A
cephalic vein graft was interposed in the femoral artery for comparison
with in situ veins. The animals were fed a diet that sustains plasma
cholesterol levels of approximately 225 mg/dl. Saphenous veins and the
cephalic vein grafts were explanted at 3 months for biochemical and
histologic analyses. Cholesterol content in undistended saphenous veins was
similar to that in veins distended at 125 or 350 mm Hg--105 +/- 15, 122 +/-
14, and 109 +/- 30 micrograms/100 mg wet tissue weight, respectively.
Cholesterol content in cephalic vein grafts, 473 +/- 122 micrograms/100 mg,
was greater (p less than 0.001) than in saphenous veins at all distention
pressures studied. There was no difference among the distention pressures
in the intimal fraction of saphenous vein wall, with the pooled value being
20% +/- 12%. This contrasted with the value of 59% +/- 11% in cephalic vein
grafts (p less than 0.01). Endothelial coverage of the luminal surface in
saphenous veins was similar among the levels of barotrauma, with the pooled
value being 83% +/- 15%. Less of the lumen was covered with endothelium in
cephalic vein grafts, 46% +/- 18% (p less than 0.01). Slightly more medial
fibrosis was observed in cephalic vein grafts as compared with saphenous
veins (p less than 0.05). These data demonstrate that barotrauma alone does
not cause veins that remain in the venous system to undergo the lipid
uptake or morphologic changes that occur in veins grafted into the arterial
circulation in nonhuman primates.