Faculty Bibliography

PURPOSE: The expression of c-MYC oncoprotein in proliferating smooth muscle cells (SMCs) was analyzed in an experimental model of vein graft intimal thickening. METHODS: Superficial epigastric vein grafts were inserted into the femoral arteries of male Sprague-Dawley rats. The vein grafts were harvested at 6 hr, 2 days, 1 week, 2 weeks, and 4 weeks after grafting and were rapidly frozen in liquid nitrogen. Immunohistochemical labeling and morphologic analysis of vein graft sections with a double staining technique were used to identify c-MYC/alpha SMC actin and proliferating cell nuclear antigen (PC10)/alpha SMC actin within intimal cells. c-MYC/alpha SMC actin and PC10/alpha SMC actin positive cells were quantitated in the perianastomotic area (R-1) and the body of the graft (R-2) for each time period. Total wall and intimal thickness of perfusion fixed vein grafts were measured with a computer digitized system. RESULTS: Intimal and total wall thickening in the R-1 region peaked at 1 week (27.4 and 579.4 microns respectively) and were significantly thicker (P < 0.01) than the same region at 6 hr after graft implantation (6.0 and 113.5 microns respectively). Staining for c-MYC and PC10 in R-1 was also significantly higher (P < 0.05) at 1 week (5.75 and 7.00 positive cells/10 cells, respectively) compared with that at 6 hr (1.5 and 1.33, respectively). The R-1 region stabilized and remodeled over the following 3 weeks, while c-MYC and PC10 staining progressively decreased. In the R-2 region, intimal thickness significantly increased (P < 0.05) from 6 hr (4.0 micrometers) to 1 week (12.0 micrometers) and stabilized, while total wall thickness increased throughout the first week and the difference became significant at 2 weeks (P < 0.05). Staining for c-MYC and PC10 paralleled the staining in R-1 with a significant peak at 1 week (P < 0.05). CONCLUSIONS: c-MYC oncoprotein is expressed early after experimental vein grafting, with peak expression at 1 week. This occurs during a period of maximal intimal thickening, SMC proliferation, and increased expression of PC10. Expression of c-myc protooncogene may contribute to the induction and regulation of SMC proliferation, producing intimal hyperplasia

PURPOSE: The purpose of this study was to evaluate the merit of polytetrafluoroethylene (PTFE) extensions and interpositions for the management of failing infrainguinal vein bypass grafts. METHODS: The treatment of 133 failing vein grafts in 125 patients over a 10-year period was retrospectively reviewed. Twenty-two graft-threatening lesions were detected in patients who did not have a usable autogenous vein conduit as determined by preoperative and intraoperative evaluations. A PTFE extension or interposition graft was used for the necessary reconstruction in all cases. RESULTS: Ten lesions were within the vein graft, 11 were proximal to the graft in the femoral or popliteal artery segments, and one was distal to the graft in the popliteal artery. The treatment of these lesions included 19 extensions and three mid graft interpositions. The vein graft lesions developed significantly sooner (mean 10.6+/-2.5 months) after the bypass (p<0.05) than the arterial lesions (mean 28.0+/-6.1 months). The 3-year cumulative secondary patency rate for these vein grafts treated with PTFE extensions or interpositions was 84%+/-8%. This was not significantly different from the 3-year cumulative secondary patency rate for vein grafts treated with vein extensions or interpositions at our institution over the same time period (82%+/-10%). The 3-year limb salvage rates were 95% and 89%, respectively. CONCLUSIONS: These results indicate that PTFE extensions and interpositions can be used successfully to maintain the patency of failing vein grafts and may serve to prolong limb salvage in patients without any usable autogenous vein. Early reintervention with a PTFE conduit in this difficult group of patients is appropriate to salvage a failing vein graft

PURPOSE: This study was undertaken to evaluate our results of polytetrafluoroethylene (PTFE) tibial and peroneal artery bypasses done for limb salvage. METHODS: Within a group of patients undergoing infrainguinal limb salvage bypasses at our institution between January 1986 and May 1995, 63 patients faced an immediate amputation, had no autologous vein on duplex examination and operative exploration, and had only a tibial or peroneal artery as an outflow vessel for bypass. Most of these patients (82%) had two or more prior ipsilateral infrainguinal bypasses. These 63 patients underwent 66 PTFE bypasses to a tibial or peroneal artery without a distal anastomotic vein cuff or an adjunctive arteriovenous fistula. Our results were then compared with those reported from infrapopliteal (crural) bypasses performed with alternate autologous vein sources or PTFE in conjunction with various recommended adjuncts. RESULTS: The 3- and 5-year cumulative primary graft patency rates for our PTFE infrapopliteal bypasses were 39%+/-7% and 28%+/-9%, respectively. Secondary graft patency rates were 55%+/-8% and 43%+/-10% at 3 and 5 years, respectively. Limb salvage rates were 71%+/-7% at 3 years and 66%+/-8% at 5 years. Two-year actuarial patient survival rate was only 67%+/-7%. CONCLUSIONS: These results indicate that a PTFE bypass to an infrapopliteal artery remains a worthwhile option in patients without usable autologous vein. The secondary patency and limb salvage rates were acceptable in this setting and were not significantly different from the best results reported with prosthetic tibial/peroneal bypasses with distal vein cuffs or patches (74% at 1 year; 58% at 3 years), arteriovenous fistulas (71% at 1 year) or composite arm vein grafts (39% and 29% at 3 and 5 years, respectively)