Long-Term Results of Venous Bypass for Lower Extremity Arteries with Selective Short Segment Prosthetic Reinforcement of Varicose Dilatations
Article Outline
The long-term benefit of venous bypass has been clearly demonstrated, but procedure feasibility is contingent upon availability of a suitable vein. In this study, we evaluated the outcome of venous bypasses performed by the first author using veins presenting dilatations that were selectively reinforced with a short prosthesis. The purpose was to answer three questions. First, should ectasis be reduced before reinforcement? Second, do hyperplasia and stenosis develop in reinforced zones? Third, do dilatation and rupture develop in unreinforced zones? Twelve patients, including 10 men and 2 women ranging in age from 36 to 77 years (median 68), underwent bypass for peripheral artery disease in seven cases, popliteal aneurysm in four, and prosthetic rupture in one. Ten patients had poor distal runoff. The bypass was femoral-to-popliteal in eight cases, femoral-to-infrapopliteal in three, and popliteal-to-popliteal in one. The graft was reversed in nine cases and ex situ devalvulated in three. The number of prosthetic reinforcements used was one in two cases, two in three cases, three in six cases, and four in one case. All but one prosthetic reinforcement were made of polytetrafluoroethylene (PTFE). Bypass occlusion was observed in two cases, including one case observed in the early postoperative period after bypass for limb salvage in a young man in whom distal runoff was limited to a few collaterals and one case that occurred 4 years after a repeat bypass procedure. The other 10 bypasses remained patent throughout follow-up, which varied from 1 to 11 years (median 4). There were three deaths during follow-up. Doppler ultrasound revealed no stenosis in the reinforced zones and no dilatation in the unreinforced zones but demonstrated progressive deterioration of the runoff in 50% of cases. At the last follow-up examination, two bypasses were patent despite poor runoff. Although the number of patients in this series was small, the outcome of venous bypass using reinforced vein grafts appeared clearly better than outcomes of prosthetic bypass reported in the literature. Reinforcement can be easily achieved using a short, thin-walled PTFE prosthesis adjusted to the proper diameter by gentle dilatation using forceps. Unlike most authors, we do not recommend reducing dilatation by resection or oversewing. Reinforced zones did not develop stenosis and unreinforced intermediate zones showed little or no dilatation and no risk of rupture.
Introduction
Infrainguinal bypass is generally considered more beneficial using vein grafts than prosthetic grafts for all indications, and the benefits increase as a function of the length of the bypass, i.e., distal popliteal artery, below-knee arteries, and ankle arteries. According to the Transatlantic Inter-Society Consensus (TASC),1 mean 5-year patency rates following bypass for intermittent claudication are 80% with vein grafts regardless of bypass configuration, 75% with polytetrafluoroethylene (PTFE) grafts used for above-knee bypass, and 65% for PTFE grafts used for below-knee bypass. For femoral-to-popliteal bypass in patients with critical ischemia, the respective patency rates are 66%, 47%, and 33%. Recommendation 92 states that “an adequate greater saphenous vein graft is the best conduit for femoral to lower and distal popliteal artery bypass. If an adequate greater saphenous vein graft is unavailable, another good quality vein graft should be used.” In the chapter entitled “Stenosis or Isolated Occlusion of the Superficial Femoral Artery at the Intermittent Claudication Stage (Version 2000),” the Decision-making Guidelines in Vascular Surgery published by the French College of Vascular Surgery2 simply state that “various studies have demonstrated the greater benefits of bypass using vein grafts.” If a saphenous vein graft is unavailable, many investigators have demonstrated the value of bypass using arm3, 4 or composite5 vein grafts.
However, in everyday practice, vascular surgeons frequently encounter situations in which an adequate vein graft is unavailable for a variety of reasons, such as previous destruction during treatment for varicose veins, harvesting for another bypass procedure, presence of fibrotic vein walls, insufficient diameter, or presence of varicose dilatations. Regarding varicose dilatations, it is not unusual to observe isolated segments of ectasis in a vein of otherwise adequate diameter. This situation raises a number of issues, such as whether the vein should be rejected because dilatation could progress to rupture, whether resection of the dilatation requiring multiple anastomoses results in higher risk, and whether oversewing could cause stenosis or fragility of the wall.
An alternative solution to allow use of vein grafts with varicose dilatation involves selective reinforcement using short prosthetic grafts. In a previous study, we reported promising preliminary results using vein grafts that had been reinforced either in selected areas or along the full length.6 Further experience indicates that selective reinforcement of localized varicose dilatation provides equivalent short-term results to full-length reinforcement. Selective reinforcement is easier to perform since there is less danger of damaging the vein during insertion into a short prosthetic segment than a long one.
This retrospective study describes the fate of bypasses performed by the first author using veins presenting dilatations selectively reinforced with a short prosthetic graft. The purpose of this study was to answer three questions. First, should ectasis be reduced before reinforcement? Second, do hyperplasia and stenosis develop in reinforced zones? Third, do dilatation and rupture develop in unreinforced zones?
Patients and Methods
From 1992 to 2001, the selective short segment reinforcement technique was used in 12 patients requiring infrainguinal bypass. There were 10 men and 2 women ranging in age from 36 to 77 years (median 68). Eight patients had occlusive arterial disease, including six with disabling claudication that did not respond to conventional medical treatment, one with permanent pain (Leriche and Fontaine stage III), and one with trophic manifestation on the heel and toes. Two of these patients had combined femoral artery occlusion and early-stage popliteal artery aneurysm. Runoff was normal in only one patient. In the remaining cases, runoff was abnormal, including four patients in whom two distal arteries were occluded but one communicating vessel to the plantar arch remained, three in whom one or two distal arteries failed rapidly, and one in whom only a few small collaterals arising from the tibioperoneal trunk were present. Risk factors in these patients were standard. The 36-year-old patient who presented critical ischemia had a family history of peripheral artery disease and smoked two packs of cigarettes per day.
Three patients presented popliteal aneurysms. One of these patients was asymptomatic, but arteriography demonstrated occlusion of the anterior tibial artery. Another patient presented partial thrombosis and runoff was limited to the peroneal artery. In the third patient, a previous venous bypass occluded, leading to acute ischemia treated by thrombolysis that left numerous clots, and contralateral operation was indicated due to the diameter of the contralateral popliteal aneurysm. The third patient, who had undergone multiple procedures for arterial occlusive disease, presented a femoral false aneurysm and a femoral-to-proximal popliteal bypass that had ruptured in three places, with runoff being reduced to the peroneal artery.
The infrainguinal bypass was femoral-to-popliteal artery in eight cases, femoral-to-distal artery in three, and popliteal-to-popliteal artery in one. In function of anatomical conditions, a reversed graft was used in nine cases and an ex situ devalvulated graft in three. In 11 cases, the bypass graft was the great saphenous vein. The remaining bypass graft was a continuous radial and cephalic vein segment that had been previously dilated by creating an arteriovenous fistula.
Conventional harvesting and anastomosis techniques were used in all cases. The diameter of the vein graft varied 4-9 mm. Vein graft diameter was 5 mm in five cases. The vein was inserted into the prosthetic graft and positioned so as to avoid folding at the level of flexion. The prosthetic graft used for reinforcement was a segment of Dacron® mesh (Cardial, France) in one case, a standard PTFE prosthesis in seven, and a thin-walled 6 mm PTFE tube designed for carotid artery bypass (Gore, Flagstaff, AZ) in four. The length of the reinforcement graft varied 2-6 cm, and the number of reinforcement grafts used was one in two cases, two in three cases, three in six cases, and four in one case. To keep the reinforcement graft from slipping during insertion into the introducer, one or both ends were attached to the adventitia using a single point of a 7.0 suture. Completion arteriography was performed to check for defects. Follow–up examinations with Doppler ultrasound were carried out in all patients at 1 month and 1 year after the procedure. Thereafter, all patients were advised to have yearly follow-up examinations with Doppler ultrasound and to consult immediately in case of abnormal ultrasound findings or clinical symptoms. For this study, patients were contacted and asked to either come in for examination or send in their last Doppler ultrasound study report.
Results
The bypass performed for limb salvage in the 36-year-old man occluded rapidly and amputation was required. The distal anastomosis was made at the end of the popliteal artery despite extensive infiltration. Since intraoperative arteriography showed high-grade narrowing of the tibioperoneal trunk, a guidewire was inserted down to the anterior tibial artery and the tibioperoneal trunk was dilated using a 3 mm balloon. Insertion down to the anterior tibial artery was not planned. In this patient, vein graft occlusion was not attributable to reinforcement of the vein graft but to poor runoff.
Follow-up periods for the reinforced vein grafts in the remaining 11 patients ranged 13-133 months (mean 47). Three patients died due to intercurrent causes with patent vein grafts at 1 year (n = 2) and 2 years (n = 1). The duration of follow-up in the eight surviving patients was 1 year in one case, 4 years in four cases, 5 years in one case, 6 years in one case, and 11 years in one case. One patient presented bypass occlusion at 4 years and required amputation. In this patient, the indication for bypass using reinforced venous graft was revascularization after thrombosis of the previous graft treated by thrombolysis that led to partial reopening but with numerous distal clots. The reinforced vein grafts in the remaining seven patients were patent at the end of follow-up. One of these patients presented stenosis of the proximal anastomosis at 6 months that was treated by short prosthetic bypass. This complication was not related to prosthetic reinforcement. One patient presented minor dilatation (1 mm) of the vein graft.
Overall findings showed that there was no stenosis of the reinforced segments or dilatation in intermediary zones. However, 50% of patients presented progressive deterioration of distal runoff. At the end of follow-up, two reinforced vein grafts were patent despite dead-end runoff.
Discussion
The reversed vein graft used as a conduit for the first long venous bypass procedure performed by Kunlin in 1948 presented a varicose dilatation. That graft remained patent until the patient died 28 years after the procedure. Although the dilatation remained stable, it was treated by resection followed by direct suture during aortobifemoral prosthetic bypass procedure carried out 14 years later. After 20 years, about one-third of the venous bypass exhibited dilatation, and at 27 years atheroscelorosis was observed by palpation during reoperation for false aneurysm of the proximal anastomosis.7
Aneurysmal dilatation is a rare complication following venous bypass.8, 9, 10, 11, 12, 13 Although aneurysmal dilatation can lead to rupture,12, 13 experience reported in the literature, as well as our own unpublished data, shows that early detection always allows successful treatment either by partial replacement of the graft or by external prosthetic reinforcement depending on the extent of dilatation. The mean delay for occurrence of aneurysmal dilatation is 7 years.8 The cause of graft dilatation is unclear. Several mechanisms have been implicated, i.e., atheroma,9, 11 although the appearance of tissue in the dilated zone is often the same as in the rest of the graft;14 continued smoking; and presence of aneurysmal disease. Regarding the role of aneurysmal disease, a prospective study reported by Loftus et al.10 showed that 42% of venous aneurysms occurred in bypasses for popliteal aneurysms versus 2% in bypasses for chronic ischemia. It is reasonable to suspect that the risk for aneurysm might be particularly high for veins presenting one or several varicose dilatations since the thinness of the walls of these lesions could signal generalized weakness of the vessel wall. No aneurysm was observed in our experience, but an anecdotal account has been brought to our attention. No such complications were reported in three other studies: Moritz et al.,15 who included nine short segmental reinforcements; Soury et al.,16 who included one short segmental reinforcement; and Neufang et al.,17 who reported 28-month follow-up findings after 35 bypass procedures that were all performed using grafts reinforced with short segment reinforcement using PTFE.
Another potential complication is development of hyperplastic stenosis in reinforcement sites. In an experimental study in sheep that confirmed a previous report, Moritz et al.15 observed evidence of a decrease rather than an increase in hyperplasia in the middle portion of sheep jugular veins that had been fully inserted into Dacron mesh tubes and used for femoral-to-popliteal bypass. The same authors observed no evidence of hyperplasia in a clinical study including 19 bypass procedures and stated that the only evidence of graft stenosis was observed in an unreinforced zone. Similarly, no evidence of hyperplasia was found by Soury et al.,16 by Neufang et al.,17 or by us. Since hyperplasia is a consistent effect of vein arterialization, it can be speculated that full reinforcement using a mesh tube might reduce hyperplasia by lowering the stresses applied to the wall by arterial blood flow.15 In a previously published animal study, Karayannacos et al.18 found that reduction of hyperplasia occurred only with mesh tubes allowing passage of vasa vasorum and that reinforcement using nonporous material led to thickening of the wall. However, like Neufang et al.,17 we used PTFE and observed no stenosis. A possible explanation for this difference is that we performed short segment reinforcement.
A possible shortcoming of our study is the short length of the mean follow-up period, which was slightly less than 4 years, and the small size of the patient population. Regarding follow-up, it should be said that it was sufficient to assess the risk of hyperplasia since it usually develops within the first year. Follow-up was too short to assess the risk of aneurysms, but that complication can be detected by annual clinical and Doppler ultrasound examination and easily repaired, often under local anesthesia. Neufang et al.17 reported similar findings in a series including nearly three times as many bypasses as ours. In their study, the 4-year primary and assisted patency rates of reinforced vein grafts were 66% and 82%, respectively. This is higher than similar rates reported for prosthetic grafts in the literature. A likely explanation involves preservation of wall compliance and of the antithrombogenic effects of the intima.
Six other technical points should be mentioned. The first point is that resection or plication in order to reduce dilatation is unnecessary. Unlike Soury et al.,16 we found that dilatations adapt well to the reinforcement prosthesis and cause no problem. Moritz et al.15 noted that a 50% reduction in vein diameter had no adverse effect. The second point involves collaterals in reinforced zones. Small collaterals can be closed using a lightweight suture, but larger collaterals should be sutured to prevent them from protruding into the vein lumen. The third point is that the vein must be placed such that the reinforcement prosthesis is not positioned at the point of knee flexion, which is located just above the midline of the knee. The fourth point is that the most suitable material for vein graft reinforcement appears to be a thin-walled PTFE tube. The diameter of these tubes can be easily expanded to fit case requirements using forceps. The fifth point is that care must be taken to keep the reinforcement prosthesis from slipping during passage of the introducer. We recommend attachment of one or both ends to the adventitia using a 7.0 suture. The sixth point is that lifelong follow-up is necessary. Patients with reinforced vein grafts should undergo Doppler ultrasound surveillance once a year. This technique can also be used for in situ bypasses by opening the prosthetic graft on one side and then sewing the edges back together over the vein.
Conclusion
The presence of a few varicose dilations in a vein of otherwise acceptable diameter should not be considered as a contraindication for use as a vein graft in patients with no other available vein. Use of such veins after prosthetic reinforcement of the dilated zones can achieve patency rates higher than those achieved using prosthetic grafts. This technique was used to avoid prosthetic bypass in 3.8% of 932 infrainguinal bypasses included in the series described by Neufang et al.17 Awareness of this option is necessary not only to those who perform this type of surgery but also to surgeons and angiologists who treat varicose veins.
References
- . Management of peripheral arterial disease. J Vasc Surg. 2000;31:S113–S116S217–S222
- Collège Français de Chirurgie Vasculaire, Brenot R. Repères pour les décisions en chirurgie vasculaire 2000;31–35.
- The use of arm vein in lower-extremity revascularization: results of 520 procedures performed in eight years. J Vasc Surg. 2000;31:50–59
- Arm vein is superior to composite prosthetic-autogenous grafts in lower-extremity revascularization. J Vasc Surg. 2000;31:1119–1127
- The use of spliced vein bypasses for infrainguinal arterial reconstruction. J Vasc Surg. 1995;21:403–412
- . Wrapped autologous greater saphenous vein bypass for severe limb ischemia in patients with varicose veins: preliminary report. J Cardiovasc Surg. 1995;36:117–120
- . Evolution sur 28 ans d'un long pontage veineux fémoro-poplité pour artériopathie—Actualités Chirurgicales. In 79éme Congrès Francais de Chirurgie. Paris: Masson; 1978;
- Infrainguinal aneurysm formation in arterialized saphenous vein grafts. J Vasc Surg. 1988;28:944–948
- . Aneurysmal dilatation in saphenous vein bypass grafts. J Cardiovasc Surg. 1990;31:668–671
- Prevalence of true vein grafts aneurysms: implication for aneurysms pathogenesis. J Vasc Surg. 1999;29:403–408
- Mega-aneurysmal degeneration of a saphenous vein graft following infrainguinal bypass: a case report. Vasc Endovasc Surg. 2004;38:267–271
- . Aneurysmal rupture of a femoropopliteal saphenous vein graft. Surgery. 1990;107:468–470
- Rupture à la peau d'un anévrisme athéromateux sur un pontage veineux fémoro-poplité par veine in-situ. Presse Méd. 1996;25:1631–1632
- . Pathophysiology of vein grafts failures: a review. Eur J Endovasc Surg. 1995;9:7–18
- The use of mesh-tube-constricted dilated or varicose vein as arterial bypass conduit. Thorac Cardiovasc Surg. 1992;40:356–360
- Prosthetic reinforcement of varicose saphenous vein grafts for infrainguinal bypass. Ann Vasc Surg. 1999;13:290–293
- External reinforcement of varicose veins with PTFE prosthesis in infrainguinal bypass surgery: clinical results. Thorac Cardiovasc Surg. 2003;51:62–66
- . Late failure in vein grafts: mediating factors in subendothelial fibromuscular hyperplasia. Ann Surg. 1978;187:183–188
PII: S0890-5096(06)00011-2
doi:10.1016/j.avsg.2006.10.005
© 2007 Annals of Vascular Surgery Inc. Published by Elsevier Inc All rights reserved.
