THE EFFECT OF THROMBUS ON THE VASCULAR ENDOTHELIUM OF ARTERIALIZED VEIN GRAFTS

BACKGROUND: If is known that vein grafts can be salvaged by clot remov al, but patency rates are diminished, This study was designed to deter mine the effects of thrombus on vascular endothelium and the ability o f the endothelium to recover normal function. METHODS: Thirty external jugular vein grafts were placed as bilateral femoral artery interposi tion grafts in 15 mongrel dogs and allowed to arterialize for a period of at least 12 weeks. Six control grafts were not exposed to thrombus (C-NT). Six other control grafts were exposed to thrombus for 7 days and removed, ie, allowed no in vivo recovery (C-T). The remaining 18 g rafts in 9 canines were exposed to autologous thrombus for 5 days and then flow was restored. The right femoral graft was removed 7 days aft er thrombectomy and the left removed 30 days after thrombectomy. At th e time of removal, the grafts were perfused with a balanced salt solut ion alone and then with arachidonic acid added to the same volume of t he salt solution. Perfusates were collected at 5, 15, and 30 minutes. These perfusates were assayed for the presence of 6-keto-prosglandin F -1 alpha (6-keto-PGF1(1 alpha)), a metabolite of prostacyclin (PGI2). Over the 30-day recovery period, the amounts of 6-keto-PGF1(1 alpha) p roduced with and without arachidonic acid added were compared to asses s endothelial response. Electron micrographs of the endothelium of all vein grafts were compared to the assay findings. RESULTS: When arachi donic acid was added to the perfusion system, there was a severalfold increase in the production of 6-keto-PGF1(1 alpha) over baseline in al l grafts allowed recovery, Grafts (C-T) that were allowed no in vivo r ecovery had no response to arachidonic acid. Ratios of 6-keto-PGF1(1 a lpha) production with arachidonic acid stimulation to 6-keto-PGF1(1 al pha) production without stimulation were calculated to compare endothe lial function. The electron micrographs showed the vascular endotheliu m to be severely injured after contact with thrombus, but recovered by 7 days. CONCLUSIONS: This study suggests that the endothelium of cani ne vein grafts is injured by contact with thrombus for 5 days but can recover structure and function. This recovery is detectable at 7 days post-thrombectomy.