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Prosthetic bypass with a distal vein patch for limb salvage
Prosthetic Bypass with a Distal Vein Patch for Limb Salvage Richard F. Neville, MD, Christopher Attinger, MD, Anton N. Sidawy, MD, Washington, DC
BACKGROUND: Certain patients require tibial bypass for limb salvage without adequate vein available as the conduit. Polytetrafluoroethylene (PTFE) bypasses result in decreased patency prompting the addition of venous tissue at the distal anastomosis as cuffs, collars, and boots. We assessed feasibility and graft patency of a distal vein patch (DVP) interposed between PTFE and the tibial artery. METHODS: Between 7/93 and 7/96,148 tibial bypasses were performed with 25 (17%) using . PTFElDVP as the conduit. Patient demographics (n = 24) were 11 males and 13 females, mean age of 67, diabetes (n = 15,57%), renal failure (n = 8, 31%), and excessive cardiac risk (n = 20, 83%). All patients had limb-threatening ischemia with rest pain in 14 (58%) and gangrene/nonheali~g ulcer in 10 (42%). Lack of vein was due to previous failed bypass (15,63%), cardiac surgery (5,21.%), and unsuitable vein (4,21%). Patients were discharged on coumadin with follow-up at 1 month, 6 months, and annually. RESULTS: PTFElDVP bypasses originated from the CFA (13,48%), the SFA (3,11%) and the e.xternal iliac artery due to previous groin diss~ctl~n. (9,41%). Recipient arteries included anterior tibial (7), posterior tibial (8), and peroneal (10)•.Followup ranged from 1 to 36 months. Cumulative graft patency at 6 months and 3 years was .91% and 78%, respectively, by life table analysts. Limb salvage was 91%. CONCLUSION: These early data indicate that tibial bypass with PTFElDVP as the conduit results in acceptable patency and limb salvage. In the patient without adequate vein, PTFE bypasses to tibial arteries for limb salvage may be improved with a distal vein patch. Am J Surg. 1997;174:173-176. © 1997 by Excerpta Medica, Inc.
utogenous saphenous vein is the. pr~ferred conduit for lower extremity revascularization. However, there exists a certain population of patients who require a tibial bypass for limb salvage without adequate
A
From the Department of Surgery, Section o~ Vascular Surgery, Georgetown University Medical Center, Washlng~on, DC. . Requests for reprints should be addressed to Richard F. Neville, MD, Department of Surge'!', 4 PHC, Ge~rgetown University Medical Center 3800 Reservoir Road, Washington, DC 20007. Presented at the 25th Annual Meeting of The Society for Clinical Vascular Surgery, Naples, Florida, March 12-16, 1997.
vein available. The search for an alternative conduit in the absence of saphenous vein has stimulated the use of polytetrafluoroethvlene (PTFE) bypasses With the recent addition of venous tissue at the distal anastomosis in the form of cuffs, collars, and boots. We assessed the technical feasibility of tibial artery bypass using PTFE with a distal vein patch (DVP).
METHODS Between July 1993 and July 1996, 148 tibial artery bypass procedures were performed for limb salvage. Of this group, 24 patients did not have adequate saphenous vein, and 25 bypasses were performed using PTFE/DVP as the conduit. This represented 17% of the tibial bypasses performed during that time period. The 24 patients included 11 males and 13 females with a mean age of 67 years. Risk factor analysis revealed 15 diabetic patients (57%), 8 patients with renal failure (31%), and 20 patients with excessive cardiac risk (83%) by Eagle's criteria.' All patients had limb-threatening ischemia as the indication for revascularization with rest pain in 14 (58%) and gangrene or nonhealing ulceration in 10 (42%). A search for saphenous vein (ipsilateral or contralateral) was made in all patients by careful physical examination supplemented with Duplex ultrasound evaluation. In each patient the ipsilateral and contralateral greater saphenous vein was not present or unsuitable for bypass because of inadequate length or quality. If the vein was of questionable quality preoperatively, then it was evaluated under direct vision at operation. The lesser saphenous vein was also not sufficient by Duplex ultrasound evaluation in these patients. Reasons for a lack of usable saphenous vein included a previous failed revascularization at an outside institution in 15 patients (63%), previous cardiac surgery in 5 (21%), and unsuitable vein due to size or sclerosis in 4 (21%). All revascularizations were performed under epidural anesthesia with arterial lines and selective use of Swan-Ganz catheterization. Proximal exposure of the artery chosen as the inflow site was obtained using a standard groin dissection for the femoral artery or a retroperitoneal approach to the external iliac artery. Distal exposure varied according to the tibial artery chosen as the outflow site. The anterior tibial artery was exposed through an approach lateral to the border of the tibia. The posterior tibial and proximal peroneal arteries were exposed medially with the distal peroneal exposed laterally after segmental resection of the fibula. After proximal and distal arterial exposure, a 2- to 3-cm segment of vein was harvested from any available location. In 23 cases a piece of vein was found in the ipsilateral or contralateral lower extremity, with arm vein harvested under supplementary local anesthesia in 2 cases. An externally reinforced PTFE graft was tunnelled between the proximal
l
© 1997 by Excerpta Medica, Inc. All rights reserved.
0002-9610/97/$17.00 PI! S0002-9610(97}00091-3
173
PROSTHmC BYPASS WITH DISTAL VEIN PATCH/NEVILLE ET AL
Figure 1. Venous patch is sutured to tibial artery with a line (A to Bl, indicating the appropriate position for the venotomy prior to PTFE implantation.
Rgure 3. Intraoperative photograph corresponding to the drawing in Figure 2. Forceps hold the polytetrafluoroethylene graft above the bulging vein patch.
-
-
-
-
-
-
-
--::c~"'. -~
Rgure 2. The PTFE graft is implanted into the vein patch, resulting in a distal vein cuff configuration.
and distal dissections in an anatomic course if feasible. After heparinization. the proximal anastomosis was performed in the usual end-to-side fashion. A 2 to 3 cm arteriotomy was then performed in the artery chosen for distal anastomosis. The venous segment was opened longitudinally and cut to the appropriate length and width in preparation for the patch. The vein patch was sutured to the artery using a standard parachute technique. A longitudinal venotomy was then made in the proximal two thirds of the patch. The venotomy was positioned in order to begin the heel of the PTFE/vein patch anastomosis just beyond the suture line of the patch (Figure 1). The PTFE graft was cut to the appropriate length in a sigmoidal fashion to allow the sides to flare in a "cobrahead" configuration. The PTFE was then sutured to the vein patch using a standard parachute technique. Ideally, the vein patch expanded in a cufflike configuration under arterial flow without ballooning into a protuberant bulge (Figures 2 and 3). Completion arteriography was performed in each case (Figure 4). Patients were transferred to the intensive care unit and started on a heparin infusion 6 hours postoperatively with conversion to coumadin for long-term anticoagulation. Patients were seen in the office 7 to 10 days after discharge from the hospital. Physical examination, ankle pressures and waveforms. and graft duplex evaluation was performed at 3 months, 6 months. and then annually.
Rgure 4. Completion arteriogram of posterior tibial bypass using a polytetrafluoroethyleneldistal vein patch conduit; note the slight increase in opacification in the area of the vein patch.
RESULTS Bypass grafts originated from the common femoral artery in 13 cases (48%). the superficial femoral artery in 3 cases (11 %), and the external iliac artery due to severe scar formation after previous groin dissection in 9 cases (41%). Recipient arteries included the peroneal (10), posterior tibial (8). and anterior tibial (7). Four grafts failed during follow-up. Two failed grafts were to posterior tibial arteries and 2 were to peroneal arteries. One graft failure occurred after 17 months and was revised with a distal extension using a new segment of PTFE and new vein patch. Another graft failed after 18 months and was converted to an ilioprofunda 174
THE AMERICAN JOURNAL OF
SURGERY~
bypass to a diseased but patent second portion of the profunda femoris artery. Two failed grafts resulted in amputation. One failure within 30 days resulted in an above-knee amputation, and one failure at 6 months resulted in below-knee amputation. Graft patency and limb salvage rates were determined using standard life table analysis with follow-up intervals ranging from 1 to 36 months. Primary graft patency was 91 % at 6 months and 78% at 3 years with three grafts remaining at risk at the 3-year interval (Figure 5). Limb salvage at 3
VOLUME 174 AUGUST 1997
PAOSTHmc BYPASS WITH DISTAL VEIN PATCHlNEVILLE ET AL
F1gwe 5. ute table analysis of cumulative patency rates of polytetrafluoroethyleneldistal vein patch bypass.
figure 8. ute table analysis of limb salvage after polytetrafluoroethyleneldistal vein patch bypass.
years was 91% (Figure 6). Two patients died from myocardial infarction during follow-up.
COMMENTS Autogenous saphenous vein is the conduit of choice for distal revascularization for limb salvage. However, there are patients requiring tibial artery bypass without available vein. Duplex ultrasound has been used to improve the ability to locate acceptable saphenous vein; however, there is certainly a subset of patients in whom the choice of conduit remains a problem. This subset of patients has been estimated near 30% of those undergoing primary bypass and 50% of those patients undergoing secondary procedures.' Several alternatives to saphenous vein have been advocated. Lesser saphenous vein, superficial femoral vein, cryopreserved vein, human umbilical vein, and PTFE have been used with varying degrees of success.1-6 Polvterrafluoroethylene has been used most commonly with generally poor long-term results. Clinical trials have reported 1- and 3-year patency rates between 20% and 58% and 12% and 37%, respecrivelv."? These bypassesto tibial arteries are certainly possible; however, due to the poor results some would argue against even an attempt at tibial bypass with PTFE for limb salvage.4.8 Composite grafts have also been constructed using PTFE and segments of available vein." However, our early experience with composite grafts was not encouraging
with myointimal hyperplasia at the PTFE-vein anastomosis often leading to graft failure. Myointimal hyperplasia is an important factor in the failure of PTFE grafts anastomosed to small tibial arteries. I O- l l Smooth muscle cell migration and proliferation results in hyperplasia beyond the toe and at the heel of the anastomosis causing a reduction in lumen area and subsequent graft failure.lo,11 Although the factors leading to myointimal hyperplasia have not been completely delineated, it has been hypothesized that the addition of venous tissue to PTFE grafts at the distal anastomosis may decrease this process. This has been demonstrated in an in vivo animal model. 14 One proposed mechanism for this reduction involves a decrease in the compliance mismatch between the artery and the PTFE graft." Theoretically, a vein cuff interposed between the stiff graft and the more pliable artery minimizes the expansibility mismatch with pulsatile flow and thus decrease mechanical injury at the anastomosis. However, these mechanical properties have not proven important in the reduction of hyperplasia in an animal model. 16 The vein may also simply enlarge the distal anastomosis so that the deposition of hyperplasia must encroach on a wider lumen making its production less critical. One could also speculate that the venous endothelium confers a beneficial physiologic effect through the inhibition of myointimal hyperplasia. Siegman 17 first advocated the use of a venous cuff in 1979 to facilitate the performance of anastomoses to calcified arteries. Miller et al 18 described a vein cuff and Taylor et al 19 a vein patch to improve the results of PTFE bypasses. Both of these configurations have led to a seeming improvement in patency versus PTFE alone, but have some theoretical and practical disadvantages. Several early graft thromboses have been reported after use of the Miller vein cuff. l o This may be related to increased turbulence caused by an excessive bulging of the venous tissue between the PTFE graft and the artery. The increased turbulence and sheer stress may lead to early graft failure. Z1 The Miller cuff has been modified by Tyrell and Wolfe! I into a venous collar with promising early clinical results. In the Taylor technique, a venous patch is constructed, resulting in primary patency of 74% at 1 year and 58% at 3 years." However, the Taylor patch requires approximately 6 cm of vein, which may be a problem in many patients. This patch also involves the direct suturing of PTFE to the artery at the heel of the anastomosis where hyperplasia is known to develop. The Taylor technique also results in a potential point of constriction in the patch where the PTFE, artery, and vein join at the midpoint of the anastomosis. 1'1 Technical nuances are certainly important in the construction of the Miller cuff, the Tyrell collar, and the Taylor patch. Because of these technical nuances and theoretical disadvantages of the cuffs. collars and patches, we performed PTFE bypasses to tibial arteries with distal vein in a vein patch configuration (Linton patch) familiar to vascular surgeons. Standard vein patch techniques were used to secure the vein to the tibial artery with a PTFE graft implanted into the venous tissue. The PTFE must be placed to the proximal two thirds of the vein patch leaving a small rim of vein at the heel of the anastomosis and a vein cuff at the distal portion of the anastomosis. Minimal vein is required. 2 to 4 ern: however, it is important to carefully trim the
THE AMERICAN JOURNAL OF SURGERye VOLUME 174 AUGUST 1997
175
PROSTHETIC BYPASS WITH DISTAL VEIN PATCH/NEVILLE ET AL
vein allowing a "pseudo cuff' to form without excessive bulging. As in all tibial reconstructions, completion arteriography is mandatory in these cases as even a minor error can lead to graft failure.
CONCLUSIONS There is no question that an aggressive policy toward limb salvage will require alternative conduits to autogenous saphenous vein in a certain number of patients. Although this was not a randomized trial, these early results indicate a PTFE graft with a distal vein patch may prove an acceptable alternative in the absence of saphenous vein. At our particular institution, PTFE with a vein patch is preferred to PTFE bypass alone or composite grafts constructed with longer vein segments. We will continue to utilize the PTFE with distal vein patch in this challenging group of patients, and a multicenter prospective randomized trial may be of benefit to address the question of the best alternative conduit for the patient without suitable autogenous saphenous vein for limb salvage.
REFERENCES 1. Eagle KA, Coley CM, Newell BA, et al. Combining clinical and thallium data optimizes preoperative assessment of cardiac risk before major vascular surgery. Ann Int Med. 1989;110:859-866. 2. Brewster DC. Composite grafts. In: Rutherford RB. ed. Vascular Surgery. 3rd ed. Philadelphia: WB Saunders; 1989:481-486. 3. Bergan JJ, Veith FJ, Bernhard VM. er al. Randomization of autogenous vein and polvtetrafluoroethvlene grafts in femorodistal reconstruction. Surgery. 1982;92:921-930. 4. Hobson RW, Lynch TG, Jamil Z, et al. Results of revascularization and amputation in severe lower extremity ischemia: a five year clinical experience. J Vase Surg. 1985;2:174-185. 5. Veith FJ, Gupta SK, Ascer E, et al. Six year prospective multicenter randomize comparison of autologous saphenous vein and expanded polyterrafluoroethylene grafts in infrainguinal arterial reconstructions. J Vase Surg. 1986;3:104-114. 6. Whittemore AD, Craig KK, Donaldson MC, et al. What is the proper role of polvretrafluoroerhylene grafts in infrainguinal reconstruction? J Vase Surg. 1989;10:299-305.
176
7. Flinn WR, Rohrer MJ, Yao JST, et al. Improved long-term patency of infragenicular polytetrafluoroethylene grafts. j Vase Surg. 1988;7:685-690. 8. Bell PRo Are distal vascular procedures worthwhile? Br J Surg. 1985;72:335. 9. Feinberg RL, Winter RP, Wheeler JR, et al. The use of composite grafts in femorocrural bypassesperformed for limb salvage: a review of 108 consecutive cases and comparison with 57 in situ saphenous vein bypasses. ] Vasc Surg. 1990;12:257-263. 10. Chevru A, Moore W. An overview of intimal hyperplasia. Surg
GynecolObstet. 1990;171:433-442. 11. Neville RF, Sidawy AN, Foegh ML. The molecular biology of vein graft atherosclerosis and myointimal hyperplasia. Ann Card
Surg. 1993;6:95-103. 12. Taylor RS, McFarland RJ, Cox MI. An investigation into the causes offailure of PTFE grafts. EurJ Vase Surg. 1987;1:335-343. 13. Bassiouny H, White S, Glagov S, et al. Anastomotic intimal hvperplasra. mechanical injury or flow induced. Surgery. 1992; 15:708-717. 14. Suggs WD, Henriquez HF, DePalma RG. Vein cuff interposition prevents juxta-anastomotic neointimal hyperplasia. Ann Surg. 1988;207:717-723. 15. Abbott WM, Megerman J, Hasson JE, et al. Effect of compliance mismatch on vascular graft patency. ] Vase Surg. 1987;5:376382. 16. Norberto J], Sidawy AN, Trad KS, et al. The protective effect of vein cuffed anastomoses is not mechanical in origin. J Vase Surg. 1995;21:558-566. 17. Siegman FA. The use of the venous cuff for graft anastomosis.
Surg Gyneeol Obstef. 1979;148:930. 18. Miller JH, Foreman RK, Ferguson L, Faris A. Interposition vein cuff for anastomosis of prosthesis to small artery. Aust NZj Surg. 1984;54:283-285. 19. Taylor RS. Loh A, McFarland RJ, et al. Improved technique for polvtetrafluoroethvlene bypass grafting: long-term results using anastomotic vein patches. Brit] Surg. 1992; 79:348-354. 20. Tyrell MR, Grigg MJ, Wolfe IN. Is arterial reconstruction to the ankle worthwhile in the absence of autologous vein? EJ Vase
Surg. 1989;3:429-434. 21. Tyrell MR, Wolfe IN. New prosthetic venous collar anastomotic technique: combining the best of other procedures. BrJ Surg. 1991;78:1016-1017.
THE AMERICAN JOURNAL OF SURGERY. VOLUME 174 AUGUST 1997
BACKGROUND: Certain patients require tibial bypass for limb salvage without adequate vein available as the conduit. Polytetrafluoroethylene (PTFE) bypasses result in decreased patency prompting the addition of venous tissue at the distal anastomosis as cuffs, collars, and boots. We assessed feasibility and graft patency of a distal vein patch (DVP) interposed between PTFE and the tibial artery. METHODS: Between 7/93 and 7/96,148 tibial bypasses were performed with 25 (17%) using . PTFElDVP as the conduit. Patient demographics (n = 24) were 11 males and 13 females, mean age of 67, diabetes (n = 15,57%), renal failure (n = 8, 31%), and excessive cardiac risk (n = 20, 83%). All patients had limb-threatening ischemia with rest pain in 14 (58%) and gangrene/nonheali~g ulcer in 10 (42%). Lack of vein was due to previous failed bypass (15,63%), cardiac surgery (5,21.%), and unsuitable vein (4,21%). Patients were discharged on coumadin with follow-up at 1 month, 6 months, and annually. RESULTS: PTFElDVP bypasses originated from the CFA (13,48%), the SFA (3,11%) and the e.xternal iliac artery due to previous groin diss~ctl~n. (9,41%). Recipient arteries included anterior tibial (7), posterior tibial (8), and peroneal (10)•.Followup ranged from 1 to 36 months. Cumulative graft patency at 6 months and 3 years was .91% and 78%, respectively, by life table analysts. Limb salvage was 91%. CONCLUSION: These early data indicate that tibial bypass with PTFElDVP as the conduit results in acceptable patency and limb salvage. In the patient without adequate vein, PTFE bypasses to tibial arteries for limb salvage may be improved with a distal vein patch. Am J Surg. 1997;174:173-176. © 1997 by Excerpta Medica, Inc.
utogenous saphenous vein is the. pr~ferred conduit for lower extremity revascularization. However, there exists a certain population of patients who require a tibial bypass for limb salvage without adequate
A
From the Department of Surgery, Section o~ Vascular Surgery, Georgetown University Medical Center, Washlng~on, DC. . Requests for reprints should be addressed to Richard F. Neville, MD, Department of Surge'!', 4 PHC, Ge~rgetown University Medical Center 3800 Reservoir Road, Washington, DC 20007. Presented at the 25th Annual Meeting of The Society for Clinical Vascular Surgery, Naples, Florida, March 12-16, 1997.
vein available. The search for an alternative conduit in the absence of saphenous vein has stimulated the use of polytetrafluoroethvlene (PTFE) bypasses With the recent addition of venous tissue at the distal anastomosis in the form of cuffs, collars, and boots. We assessed the technical feasibility of tibial artery bypass using PTFE with a distal vein patch (DVP).
METHODS Between July 1993 and July 1996, 148 tibial artery bypass procedures were performed for limb salvage. Of this group, 24 patients did not have adequate saphenous vein, and 25 bypasses were performed using PTFE/DVP as the conduit. This represented 17% of the tibial bypasses performed during that time period. The 24 patients included 11 males and 13 females with a mean age of 67 years. Risk factor analysis revealed 15 diabetic patients (57%), 8 patients with renal failure (31%), and 20 patients with excessive cardiac risk (83%) by Eagle's criteria.' All patients had limb-threatening ischemia as the indication for revascularization with rest pain in 14 (58%) and gangrene or nonhealing ulceration in 10 (42%). A search for saphenous vein (ipsilateral or contralateral) was made in all patients by careful physical examination supplemented with Duplex ultrasound evaluation. In each patient the ipsilateral and contralateral greater saphenous vein was not present or unsuitable for bypass because of inadequate length or quality. If the vein was of questionable quality preoperatively, then it was evaluated under direct vision at operation. The lesser saphenous vein was also not sufficient by Duplex ultrasound evaluation in these patients. Reasons for a lack of usable saphenous vein included a previous failed revascularization at an outside institution in 15 patients (63%), previous cardiac surgery in 5 (21%), and unsuitable vein due to size or sclerosis in 4 (21%). All revascularizations were performed under epidural anesthesia with arterial lines and selective use of Swan-Ganz catheterization. Proximal exposure of the artery chosen as the inflow site was obtained using a standard groin dissection for the femoral artery or a retroperitoneal approach to the external iliac artery. Distal exposure varied according to the tibial artery chosen as the outflow site. The anterior tibial artery was exposed through an approach lateral to the border of the tibia. The posterior tibial and proximal peroneal arteries were exposed medially with the distal peroneal exposed laterally after segmental resection of the fibula. After proximal and distal arterial exposure, a 2- to 3-cm segment of vein was harvested from any available location. In 23 cases a piece of vein was found in the ipsilateral or contralateral lower extremity, with arm vein harvested under supplementary local anesthesia in 2 cases. An externally reinforced PTFE graft was tunnelled between the proximal
l
© 1997 by Excerpta Medica, Inc. All rights reserved.
0002-9610/97/$17.00 PI! S0002-9610(97}00091-3
173
PROSTHmC BYPASS WITH DISTAL VEIN PATCH/NEVILLE ET AL
Figure 1. Venous patch is sutured to tibial artery with a line (A to Bl, indicating the appropriate position for the venotomy prior to PTFE implantation.
Rgure 3. Intraoperative photograph corresponding to the drawing in Figure 2. Forceps hold the polytetrafluoroethylene graft above the bulging vein patch.
-
-
-
-
-
-
-
--::c~"'. -~
Rgure 2. The PTFE graft is implanted into the vein patch, resulting in a distal vein cuff configuration.
and distal dissections in an anatomic course if feasible. After heparinization. the proximal anastomosis was performed in the usual end-to-side fashion. A 2 to 3 cm arteriotomy was then performed in the artery chosen for distal anastomosis. The venous segment was opened longitudinally and cut to the appropriate length and width in preparation for the patch. The vein patch was sutured to the artery using a standard parachute technique. A longitudinal venotomy was then made in the proximal two thirds of the patch. The venotomy was positioned in order to begin the heel of the PTFE/vein patch anastomosis just beyond the suture line of the patch (Figure 1). The PTFE graft was cut to the appropriate length in a sigmoidal fashion to allow the sides to flare in a "cobrahead" configuration. The PTFE was then sutured to the vein patch using a standard parachute technique. Ideally, the vein patch expanded in a cufflike configuration under arterial flow without ballooning into a protuberant bulge (Figures 2 and 3). Completion arteriography was performed in each case (Figure 4). Patients were transferred to the intensive care unit and started on a heparin infusion 6 hours postoperatively with conversion to coumadin for long-term anticoagulation. Patients were seen in the office 7 to 10 days after discharge from the hospital. Physical examination, ankle pressures and waveforms. and graft duplex evaluation was performed at 3 months, 6 months. and then annually.
Rgure 4. Completion arteriogram of posterior tibial bypass using a polytetrafluoroethyleneldistal vein patch conduit; note the slight increase in opacification in the area of the vein patch.
RESULTS Bypass grafts originated from the common femoral artery in 13 cases (48%). the superficial femoral artery in 3 cases (11 %), and the external iliac artery due to severe scar formation after previous groin dissection in 9 cases (41%). Recipient arteries included the peroneal (10), posterior tibial (8). and anterior tibial (7). Four grafts failed during follow-up. Two failed grafts were to posterior tibial arteries and 2 were to peroneal arteries. One graft failure occurred after 17 months and was revised with a distal extension using a new segment of PTFE and new vein patch. Another graft failed after 18 months and was converted to an ilioprofunda 174
THE AMERICAN JOURNAL OF
SURGERY~
bypass to a diseased but patent second portion of the profunda femoris artery. Two failed grafts resulted in amputation. One failure within 30 days resulted in an above-knee amputation, and one failure at 6 months resulted in below-knee amputation. Graft patency and limb salvage rates were determined using standard life table analysis with follow-up intervals ranging from 1 to 36 months. Primary graft patency was 91 % at 6 months and 78% at 3 years with three grafts remaining at risk at the 3-year interval (Figure 5). Limb salvage at 3
VOLUME 174 AUGUST 1997
PAOSTHmc BYPASS WITH DISTAL VEIN PATCHlNEVILLE ET AL
F1gwe 5. ute table analysis of cumulative patency rates of polytetrafluoroethyleneldistal vein patch bypass.
figure 8. ute table analysis of limb salvage after polytetrafluoroethyleneldistal vein patch bypass.
years was 91% (Figure 6). Two patients died from myocardial infarction during follow-up.
COMMENTS Autogenous saphenous vein is the conduit of choice for distal revascularization for limb salvage. However, there are patients requiring tibial artery bypass without available vein. Duplex ultrasound has been used to improve the ability to locate acceptable saphenous vein; however, there is certainly a subset of patients in whom the choice of conduit remains a problem. This subset of patients has been estimated near 30% of those undergoing primary bypass and 50% of those patients undergoing secondary procedures.' Several alternatives to saphenous vein have been advocated. Lesser saphenous vein, superficial femoral vein, cryopreserved vein, human umbilical vein, and PTFE have been used with varying degrees of success.1-6 Polvterrafluoroethylene has been used most commonly with generally poor long-term results. Clinical trials have reported 1- and 3-year patency rates between 20% and 58% and 12% and 37%, respecrivelv."? These bypassesto tibial arteries are certainly possible; however, due to the poor results some would argue against even an attempt at tibial bypass with PTFE for limb salvage.4.8 Composite grafts have also been constructed using PTFE and segments of available vein." However, our early experience with composite grafts was not encouraging
with myointimal hyperplasia at the PTFE-vein anastomosis often leading to graft failure. Myointimal hyperplasia is an important factor in the failure of PTFE grafts anastomosed to small tibial arteries. I O- l l Smooth muscle cell migration and proliferation results in hyperplasia beyond the toe and at the heel of the anastomosis causing a reduction in lumen area and subsequent graft failure.lo,11 Although the factors leading to myointimal hyperplasia have not been completely delineated, it has been hypothesized that the addition of venous tissue to PTFE grafts at the distal anastomosis may decrease this process. This has been demonstrated in an in vivo animal model. 14 One proposed mechanism for this reduction involves a decrease in the compliance mismatch between the artery and the PTFE graft." Theoretically, a vein cuff interposed between the stiff graft and the more pliable artery minimizes the expansibility mismatch with pulsatile flow and thus decrease mechanical injury at the anastomosis. However, these mechanical properties have not proven important in the reduction of hyperplasia in an animal model. 16 The vein may also simply enlarge the distal anastomosis so that the deposition of hyperplasia must encroach on a wider lumen making its production less critical. One could also speculate that the venous endothelium confers a beneficial physiologic effect through the inhibition of myointimal hyperplasia. Siegman 17 first advocated the use of a venous cuff in 1979 to facilitate the performance of anastomoses to calcified arteries. Miller et al 18 described a vein cuff and Taylor et al 19 a vein patch to improve the results of PTFE bypasses. Both of these configurations have led to a seeming improvement in patency versus PTFE alone, but have some theoretical and practical disadvantages. Several early graft thromboses have been reported after use of the Miller vein cuff. l o This may be related to increased turbulence caused by an excessive bulging of the venous tissue between the PTFE graft and the artery. The increased turbulence and sheer stress may lead to early graft failure. Z1 The Miller cuff has been modified by Tyrell and Wolfe! I into a venous collar with promising early clinical results. In the Taylor technique, a venous patch is constructed, resulting in primary patency of 74% at 1 year and 58% at 3 years." However, the Taylor patch requires approximately 6 cm of vein, which may be a problem in many patients. This patch also involves the direct suturing of PTFE to the artery at the heel of the anastomosis where hyperplasia is known to develop. The Taylor technique also results in a potential point of constriction in the patch where the PTFE, artery, and vein join at the midpoint of the anastomosis. 1'1 Technical nuances are certainly important in the construction of the Miller cuff, the Tyrell collar, and the Taylor patch. Because of these technical nuances and theoretical disadvantages of the cuffs. collars and patches, we performed PTFE bypasses to tibial arteries with distal vein in a vein patch configuration (Linton patch) familiar to vascular surgeons. Standard vein patch techniques were used to secure the vein to the tibial artery with a PTFE graft implanted into the venous tissue. The PTFE must be placed to the proximal two thirds of the vein patch leaving a small rim of vein at the heel of the anastomosis and a vein cuff at the distal portion of the anastomosis. Minimal vein is required. 2 to 4 ern: however, it is important to carefully trim the
THE AMERICAN JOURNAL OF SURGERye VOLUME 174 AUGUST 1997
175
PROSTHETIC BYPASS WITH DISTAL VEIN PATCH/NEVILLE ET AL
vein allowing a "pseudo cuff' to form without excessive bulging. As in all tibial reconstructions, completion arteriography is mandatory in these cases as even a minor error can lead to graft failure.
CONCLUSIONS There is no question that an aggressive policy toward limb salvage will require alternative conduits to autogenous saphenous vein in a certain number of patients. Although this was not a randomized trial, these early results indicate a PTFE graft with a distal vein patch may prove an acceptable alternative in the absence of saphenous vein. At our particular institution, PTFE with a vein patch is preferred to PTFE bypass alone or composite grafts constructed with longer vein segments. We will continue to utilize the PTFE with distal vein patch in this challenging group of patients, and a multicenter prospective randomized trial may be of benefit to address the question of the best alternative conduit for the patient without suitable autogenous saphenous vein for limb salvage.
REFERENCES 1. Eagle KA, Coley CM, Newell BA, et al. Combining clinical and thallium data optimizes preoperative assessment of cardiac risk before major vascular surgery. Ann Int Med. 1989;110:859-866. 2. Brewster DC. Composite grafts. In: Rutherford RB. ed. Vascular Surgery. 3rd ed. Philadelphia: WB Saunders; 1989:481-486. 3. Bergan JJ, Veith FJ, Bernhard VM. er al. Randomization of autogenous vein and polvtetrafluoroethvlene grafts in femorodistal reconstruction. Surgery. 1982;92:921-930. 4. Hobson RW, Lynch TG, Jamil Z, et al. Results of revascularization and amputation in severe lower extremity ischemia: a five year clinical experience. J Vase Surg. 1985;2:174-185. 5. Veith FJ, Gupta SK, Ascer E, et al. Six year prospective multicenter randomize comparison of autologous saphenous vein and expanded polyterrafluoroethylene grafts in infrainguinal arterial reconstructions. J Vase Surg. 1986;3:104-114. 6. Whittemore AD, Craig KK, Donaldson MC, et al. What is the proper role of polvretrafluoroerhylene grafts in infrainguinal reconstruction? J Vase Surg. 1989;10:299-305.
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7. Flinn WR, Rohrer MJ, Yao JST, et al. Improved long-term patency of infragenicular polytetrafluoroethylene grafts. j Vase Surg. 1988;7:685-690. 8. Bell PRo Are distal vascular procedures worthwhile? Br J Surg. 1985;72:335. 9. Feinberg RL, Winter RP, Wheeler JR, et al. The use of composite grafts in femorocrural bypassesperformed for limb salvage: a review of 108 consecutive cases and comparison with 57 in situ saphenous vein bypasses. ] Vasc Surg. 1990;12:257-263. 10. Chevru A, Moore W. An overview of intimal hyperplasia. Surg
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THE AMERICAN JOURNAL OF SURGERY. VOLUME 174 AUGUST 1997