Preferential Use of ePTFE For Above-Knee Femoropopliteal Bypass Grafts Robert B. Patterson, MD, Richard J. Fowl, MD, Richard F. Kempczinski, MD, Robert Gewirtz, MD, Rakesh Shukla, PhD Cincinnati, Ohio
We have used polytetrafluoroethylene preferentially for bypasses to the above-knee popliteal artery since 1979. Since this approach has recently been challenged, we reviewed our experience with 138 grafts in 128 patients. The majority (74%) of patients were male with a mean age of 63.2 years. Risk factors included: smoking (85%), hypertension (55%), diabetes mellitus (45%), and coronary artery disease (41%). The indications for operation were disabling claudication (18%), rest pain (42%), gangrene/tissue loss (33%), and miscellaneous (7%). Perioperative (30 day) mortality was 3% and morbidity (excluding amputation or graft failure) was 5%. Patients were followed for up to eight years with a mean follow-up of 22.1 months. Grafts which remained patent, but did not prevent major amputation, were classified as "failed". Primary patency was 75% at one year and 54% at five years. Limb salvage was 88% at one year and 70% at five years. Risk factors, indication for operation and arteriographic runoff had no statistically significant impact on short- or long-term patency. However, bypass grafts to isolated popliteal segments had a significantly (p = 0.025) increased perioperative failure rate compared to all other grafts. Our data support the continued use of polytetrafluoroethylene for above-knee femoropopliteal bypass except perhaps in patients who require grafting to an isolated popliteal segment where higher early failure rates were seen. (Ann Vasc Surg 1990;4:338-343). KEY WORDS:
Extended polytetrafluoroethylene grafts; popliteal artery bypass.
Since Kunlin [1] first described femoropopliteal bypass in 1949, reversed autologous saphenous vein has remained the graft material of choice for this procedure. However, between 20 and 40% of patients requiring infrainguinal bypass grafting will not have an adequate ipsilateral greater saphenous vein [2,3]. If the surgeon is willing to use arm veins or to construct composite grafts using vein fragments harvested from multiple sites, autogenous conduits can be fashioned in a significant percentFrom the Department of Surgery, Division of Vascular Surgery and the Department of Environmental Health, Division o f Biostatistics, University of Cincinnati Medical Center, Cincinnati, Ohio. Reprint requests: Richard F. Kempczinski, MD, Department of Surgery, University of Cincinnati Medical Center, 231 Bethesda Avenue, Cincinnati, Ohio 45267-0558.
age of these patients. However, such grafts do not appear to have a long-term patency equivalent to a good, greater saphenous vein. Polytetrafluoroethylene (ePTFE) grafts were first introduced for clinical use in 1973, and early experiences [4-15] suggested patency and limb salvage rates compared favorably with saphenous vein when they were used for bypasses to the aboveknee (AK) popliteal artery. A more recent prospective study [16] has shown that the results of AK femoropopliteal bypass with expanded (ePTFE) are equivalent to those with reversed saphenous vein. The clear superiority of saphenous vein over synthetic material has been consistently demonstrated for infrageniculate grafting [9,16-18]. Our policy of preferentially using prosthetic grafts for bypass to the AK popliteal artery has 338
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several attractive, albeit theoretical, advantages, Operation is expedited in debilitated, elderly patients requiring surgery for limb salvage and the greater saphenous vein is spared for subsequent use for more distal infrageniculate bypass [19,20]. Recently, several authors have challenged these arguments and recommended that, except in very unusual circumstances, prosthetic grafts should never be used below the inguinal ligament [21,22]. To address that challenge, we reviewed our eight year experience with 138 AK ePTFE femoropopliteal grafts to evaluate both their primary patency and to establish the subsequent utilization of ipsilateral greater saphenous vein.
MATERIALS AND METHODS During the period February 1979 to November 1987, 128 patients at the University of Cincinnati Medical Center and the Cincinnati Veterans Administration Hospital underwent 138 AK femoropopliteal bypasses using ePTFE. Analysis of these patients provides the basis for this report. The majority (74%) of patients were male with a mean age of 63.2 (-+ 9.7) years. Risk factors for the development of atherosclerosis included smoking (85%), hypertension (55%,), and diabetes mellitus (45%). A history of coronary artery disease was present in 41% of patients. Bypass to achieve limb salvage accounted for the majority of procedures, with rest pain as the indication for surgery in 57 (42%,) and tissue loss or gangrene in 48 (33%). Twenty-five patients (18%) underwent operation for disabling claudication, and the remaining eight had bypasses inserted for miscellaneous indications (aneurysm, atheroemboli, etc.). Patients requiring bypass for trauma were excluded from review. All patients were categorized according to the criteria suggested by the A d H o c C o m m i t t e e on Reporting Standards [23]. Graft patency was evaluated for each category and for those patients operated on for limb salvage (i.e., all patients with rest pain or tissue loss) using the lifetable method. Arteriographic runoff was determined by review of preoperative arteriograms, and classified based upon the number of patent final vessels in direct continuity with the popliteal artery. Runoff was considered satisfactory (two or three vessel) in 66 (49%) limbs, and poor (single vessel or isolated popliteal segment) in 68 (51%). However, many of the patients with satisfactory runoff had additional occlusive lesions in the distal tibial or peroneal arteries, thus helping to explain the high percentage of our patients with critical limb ischemia. Arteriograms were unavailable for review in three patients (four limbs). Follow-up was complete for 131 patients, with only seven patients lost at varying intervals after
~, if_ ~ ~, ,~ :N ~ o ~
loo 9o 8o To
339
138
48 i
so so
38
I
24
3 YEARS
4
17 i ....
7H
40 3o 2o
lo 1
2
5
6
Fig. 1. Life table analysis: Primary patency of all grafts in this series. Numbers represent grafts at risk for each interval. Those intervals where standard error of mean was -> 10% are represented graphically by broken line.
surgery. All conclusions regarding graft patency were based on objective vascular laboratory measurements performed at regular intervals after surgery. Grafts were considered patent if the postoperative ankle/brachial index remained -> 0.01 higher than the preoperative value [23] and if calf pulse volume recordings documented graft patency [24]. If there was any question of graft status following the noninvasive studies, an arteriogram was obtained to resolve the matter. However, this was rarely necessary. No patients were placed on aspirin either pre- or postoperatively to improve graft patency. However, some of them were already taking this drug on the advice of their physicians because of cerebrovascular or cardiac disease. No .pa.t!entswere placed on Coumadin following their mmal " gralt • . Grafts that were successfully salvage d by thrombectomy, with or without revision, or those that required revision to prevent failure were classified as secondarily patent. Primary patency was calculated to the date of initial revision or failure. Major amputation was required in four patients despite a patent graft, and one functioning graft was removed because of infection. These five grafts were considered as failures for the purpose of statistical analysis. Patency data was evaluated utilizing life-table analysis [23,25],
RESULTS
Overall patency
Primary patency for all AK femoropopliteal bypass grafts using ePTFE was 75% at 12 months, 61% at three years, and 54% at five years (Fig. 1,
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TABLE I.--Life table primary patency of above-knee femoropopliteal bypass grafts with ePTFE Interval (months)
# at risk at start
Failed
0-1 1-3 3-6 6-9 9-12 12-18 18-24 24-36 36-48 48-60 60-72
138 116 110 92 76 65 48 38 24 17 7
12 4 6 7 5 5 2 4 0 1 0
*standard
Duration
Lost to Follow-up
5 1 8 6 5 9 6 7 5 7 4
2 0 3 1 0 1 0 0 0 0 0
Died
Interval patency rate
Cumulative patency (%)
SE* (%)
3 1 1 2 1 2 2 3 2 2 0
0.09 0.97 0.94 0.92 0.93 0.92 0.96 0.88 1.00 0.92 1.00
100 91 87 82 75 70 64 61 54 54 50
0.00 2.6 3.0 3.6 4.3 4.8 5.5 6.2 7.5 8.9 13.4
e r r o r of t h e m e a n
Table I). Cumulative patency (including those grafts salvaged by t h r o m b e c t o m y or local revision) was 82%, 67% and 56% for the same intervals. This difference was not significant by the logrank test at each interval. Limb salvage for those patients whose indication for surgery was rest pain or tissue loss was 88% at one year and 70% at five years (Fig. 2).
were performed on subsets representing risk factors for atherosclerosis. Either alone or in combination, diabetes, hypertension or coronary artery disease did not influence short- or long-term patency. Smoking was too ubiquitous a risk factor to effectively evaluate in this population.
Influence of arteriographic runoff Influence of operative indication and risk factors for atherosclerosis
Although the small number of patients operated upon for claudication (n = 25) makes valid statistical comparison impossible beyond one year, there appeared to be no difference in one, three, or five year patency when grafts were segregated based on surgical indications. Similar life-table and logrank test comparisons
There was no difference in early or late patency if patients with satisfactory versus poor runoff were compared. Analysis of the subgroup of patients who had bypass to an isolated popliteal segment revealed a significant (p = .025) increase in early failure rate (5 of 26 grafts) within 30 days of surgery. Despite this high early failure rate, the overall patency at three and five years for such grafts patent at discharge was comparable to grafts with satisfactory runoff.
Complications ,
.J 10% are represented graphically by broken line.
Perioperative mortality was 3.1% (4 of 128 patients), all from cardiac complications. Long-term survival (90% at 12 months, 71% at three years, and 61% at five years) was consistent with other reports [26-28]. Operative morbidity included wound complications in three (3), graft infections resulting in graft removal and revision in two (2), reexploration for bleeding in one (1), and nonfatal myocardial infarction in one (1). Twelve grafts failed within the first 30 days; two of those represented amputations despite a patent graft, one patent graft was removed for infection, and two were successfully salvaged with thrombectomy and local revision. Intermediate and late failures resulted in the loss of an additional 34 grafts for a total of 46 failures over the period of this report. One patient was lost to follow-up, 16 required major amputation, and nine had no further surgery. T w e n t y patients underwent additional recon-
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TABLE II.--Primary long-term patency of ePTFE femoropopliteal bypass grafts from comparable series in the literature
Gupta [5] (1980) Evans [31 ] (1981 ) Bergan [6] (1982) McCauley [32] (1984) Christenson [4] (1985) Sterpetti [20] (1985) Veith [16] (1986) Raggerty [26] (1987) Claudication Limb salvage Rutherford [27] (1988) Quifiones-Baldrich [28] (1988) Present series
No. of grafts 92 73 33 90 153 90 91 43 63 36* 101 * 138
Primary patency 12 36 months months N/A 83% 69% 57% 82% NA 67% 50 84% 80% 82% 64% 84% 60% 79% 52% 79% 69% 83% 75%
48% 46% 74% 61%
60 months NA NA NA 43% 76% 58% NA 29% 43% NA 63% 54%
*Above knee grafts only; NA = information not available.
structive surgery following graft failure. Nine grafts were locally revised with extension of patency of the original graft by an average of 18.4 months. Ten graft failures necessitated bypass to the below-knee (BK) level. The ipsilateral autogenous saphenous vein was available for reconstruction in five of these, and ePTFE was used in the remainder. One patient had subsequent reconstruction with a composite (ePTFE-ASV) graft and one had relief of rest pain with an extended autogenous profundaplasty using endarterectomized superficial femoral artery.
DISCUSSION Although much has been written about the use of ePTFE bypass grafts in the infrainguinal position, it is difficult to draw firm conclusions based on individual or institutional experiences. Small sample size, inadequate long term follow-up, heterogeneity of indications, and level of distal anastomosis (i.e. AK popliteal, BK popliteal, and tibial vessels) all preclude valid comparisons and statistically significant conclusions. Our experience with 138 AK popliteal ePTFE bypass grafts represents one of the largest reported in the literature, with follow-up of sufficient numbers of patients for at least 60 months to provide statistically valid data. The patency rates of 75% at one year, 6t% at three years, and 54% at five years compare favorably with other similar reports (Table II). Indication for operation and arteriographic runoff have previously been reported to significantly influence the long-term patency of infrainguinal bypass grafts [18]. This contrasts with our findings, and those of others, which failed to demonstrate any difference in either short- or long-term patency based on indication (claudication, rest pain or tissue loss) [28] or arteriographic runoff [29]. Only in that
small subset of patients who underwent bypass to an isolated popliteal segment could any difference in early graft failure be demonstrated. The high (19%) early failure rate of those grafts appeared to be more a consequence of surgical optimism, i.e., attempting to revascularize a limb that was probably unsalvageable. Our three year patency of 65% for ePTFE grafts to the isolated popliteal arterial segment suggests that such bypasses perform acceptably over the long-term in appropriate patients. Quifiones-Baldrich and associates [29] recently reviewed a similar experience with 146 femoropopliteal ePTFE grafts of which 101 were above-knee. Their five-year patency for AK grafts (63%) was statistically comparable to our results despite the fact that more than half (55%) of their patients underwent operation for intermittent claudication compared to only 18% of our patients. They also found similar patency rates with both good and poor runoff. The well-documented poor performance of prosthetic vascular grafts when used for bypass to the infrageniculate popliteal artery and tibial vessels has convinced most vascular surgeons of the necessity to use autogenous grafts for reconstructions in this position. However, a patient presenting with graft thrombosis several years after an AK reconstruction with reversed saphenous vein represents a much more difficult reoperative challenge than does a similar patient in whom the saphenous vein has been previously spared. Composite autologous grafts with vein harvested from the contralateral leg (which frequently has a compromised arterial supply as well), the arm, or from the ipsilateral lesser saphenous system may not have the same good long term patency rates that have been reported with in-situ techniques [29]. Thus, given the satisfactory patency which we have achieved using ePTFE grafts in the AK position, the preferential use of this
342
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material has theoretic appeal for the preservation of saphenous vein for later reconstruction. In a review of 59 AK prosthetic reconstruction, Rosen and colleagues [19] identified eight patients (14%) who required subsequent below-knee in-situ bypass grafts. They compared this group of patients against those having an initial in-situ bypass below the knee (n = 75). At 36 months, the cumulative limb salvage rate for staged reconstructions (prosthetic followed by in-situ) was 87%, compared to 73% and 78%, respectively, for prosthetic and insitu alone. More importantly, of 14 prosthetic grafts that occluded within the study period, 10 (71%) had an available saphenous vein which could have been utilized for distal reconstruction. This contrasts with those patients undergoing in-situ grafting as the initial procedure. In this group, 11 of 16 grafts that failed resulted in a limb loss. Our data also support the concept of performing an initial AK popliteal bypass with ePTFE, thus preserving the saphenous vein for later use as an infrageniculate bypass. Of the 10 graft failures in our series which required bypass to the below-knee level, autogenous saphenous vein was available for in-situ reconstruction in five. One additional patient had reconstruction with a composite (ePTFE-ASV) graft. Because we have become more aggressive with distal reconstruction using the in-situ technique, the availability of ipsilateral vein permits us to revascularize patients with disadvantaged outflow tracts following failure of an AK bypass who would have previously come to amputation. When presented with a patient who has an isolated AK popliteal segment and reconstitution of a distal tibial artery, we select our initial bypass based on the indications for surgery. In patients presenting with gangrene or tissue loss on the forefoot, the restoration of pulsatile flow to this level appears to be critical for optimal success [30], and we would perform a bypass to the tibial vessel which communicates most directly with the pedal arch using autogenous vein. However, for the relief of rest pain we would perform a bypass with ePTFE to the AK popliteal artery. Our low early failure rate (6.7%) and high three year patency (73%) in the group of patients with rest pain and an isolated popliteal segment clearly supports this approach. The higher early failure rate of prosthetic grafts to an isolated AK popliteal segment was primarily in patients undergoing bypass for advanced gangrene with no distal reconstructible vessel. Although the long-term patency rate of 65% at three years is acceptable in this subset of patients, there is no theoretic advantage to preserving the autogenous saphenous vein. In this group, we now recommend primary bypass with ASV.
ACKNOWLEDGMENT The authors wish to express their appreciation to Rosalie Bodenham, RN, for her invaluable assistance in the collection of the data reported in this manuscript.
REFERENCES 1. KUNLIN J. Le traitment de l'arterite obliterante par la greffe veneuse. Arch Mal Coeur 1949;42:371-379. 2. SZ1LAGYI DE, HAGEMAN JH, SMITH RF, et al. Autogenous vein grafting in femoropopliteal atherosclerosis: the limits of its effectiveness. Surgery 1979;86:836--851. 3. TAYLOR LM Jr, PHINNEY ES, PORTER JM. Present status of reversed vein bypass for lower extremity revascularization. J Vasc Surg 1986;3:288-297. 4. CHRISTENSON JT, BROOME A, NORGREN L, et al. Revascularization of popliteal and below-knee arteries with polytetrafluoroethylene. Surgery 1985;97:141-149. 5. GUPTA SK, VEITH FJ. Three year experience with expanded polytetrafluoroethylene arterial grafts for limb salvage. Am J Surg 1980;140:214-217. 6. BERGAN JJ, VEITH FJ, BERNHARD VM, et al. Randomization of autogenous vein and polytetrafluoroethylene grafts in femoral-distal reconstruction. Surgery 1982;92:921-930. 7. TILANUS HW, OBERTOP H, VAN URK H. Saphenous vein or PTFE for femoropopliteal bypass. A prospective randomized trial. Ann Surg 1985;202:780-782. 8. CRANLEY J J, HAFNER CD. Newer prosthetic material compared with autogenous saphenous vein for occlusive arterial disease of the lower extremity. Surgery 1981 ;89:2-7. 9. WEISEL RD, JOHNSTON KW, BAIRD RJ, et al. Comparison of conduits for leg revascularization. Surgery 1981;89:8-15. 10. JULIAN TB, LOUBEAU J-M, STREMPLE JF. Polytetrafluoroethylene or saphenous vein as a femoropopliteal bypass graft? J Surg Res 1982;32:1-6. 11. HURWITZ RL, JOHNSON JM, H U F N A G E L CE. Femoropopliteal bypass using externally supported polytetrafluoroethylene grafts. Am J Sttrg 1985;150:574-576. 12. BENNION RS, WILLIAMS RA, STABILE BE, et al. Patency of autogenous saphenous vein versus polytetrafluoroethylene grafts in femoropopliteal bypass for advanced ischemia of the extremity. Surg Gynecol Obstet 1985;160:23%242. 13. HAIMOV H, GIRON F, JACOBSON JH II. The expanded polytetrafluoroethylene graft. Three year's experience with 362 grafts. Arch Surg 1979;114:673-677. 14. SIMONE ST Jr, DUBNER B, SAFI AR, et al. Comparative review of early and intermediate patency rates of polytetrafluoroethylene and autogenous saphenous vein grafts for lower extremity ischemia. Surgery 1981;90:991-998. 15. QUIlqONES-BALDRICH WJ, MARTIN-PARADERO V, BAKER JD, et al. PTFE grafts as the arterial substitute of first choice in femoropopliteal revascularization. Arch Surg 1984;119:1238-1243. 16. VEITH FJ, GUPTA SK, ASCER E, et al. Six-year prospective multicenter randomized comparison of autologous saphenous vein and expanded polytetrafluoroethylene grafts in infrainguinal arterial reconstructions. J Vasc Surg 1986;3:104-114. 17. CORSON JD, BREWSTER DC, LASALLE AJ, et al. Comparative analysis of vein and prosthetic bypass grafts to the isolated popliteal artery. Surgery 1982;91:448--451. 18. BREWSTER DC, LASALLE AJ, ROBISON JG, et al. Factors affecting patency of femoropopliteal bypass grafts. Surg Gynecol Obstet 1983;157:437-442. 19. ROSEN RC, JOHNSON WC, BUSH HL Jr, et al. Staged infrainguinal revascularization: initial prosthetic above-knee bypass followed by a distal vein bypass for recurrent ischemia. Am J Surg 1986;152:224-230.
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20. STERPETTI AV, SCHULTZ RD, FELDHAUS RJ, et al. Seven-year experience with polytetrafluoroethylene as above-knee femoro-popliteal bypass graft. Is it worthwhile to preserve the autologous saphenous vein? J Vasc Surg 1985;2:907-912. 21. TAYLOR LM, EDWARDS JM, BRANT B, et al. Autogenous reversed vein bypass for lower extremity ischemia in patients with absent or inadequate greater saphenous vein. Am J Surg 1987;153:505-510. 22. KENT KC, WHITTEMORE AD, MANNICK JA. Shortterm and mid-term results of an all-autogenous tissue policy for infraiguinal reconstruction. J Vasc Surg, 1989; 9:107114. 23. RUTHERFORD RB, FLANIGAN DP, GUPTA SK, et al. Suggested standards for reports dealing with lower extremity ischemia. J Vasc Surg 1986;4:80-94. 24. KEMPCZINSKI RF. Segmental volume plethysmography in the diagnosis of lower extremity arterial occlusive disease. J Cardiovasc Surg 1982;23:125-129. 25. PETO R, PIKE MC, ARMITAGE P, et al. Design and analysis of randomized trials required prolonged observations of each patient II. Analysis and examples. Br J Cancer 1977;35:1.
mmm
343
26. RAFFERTY TD, AVELLONE JC, FARRELL C J, et al. A metropolitan experience with infrainguinal revascularization. J Vasc Surg 1987;6:365-371. 27. RUTHERFORD RB, JONES DN, BERGENTZ S-E, et al. Factors affecting the patency of infrainguinal bypass. J Vasc Surg 1988;8:236-246. 28. QUIIqONES-BALDRICH WJ, BUSUT'FIL RW, BAKER JD, et al. Is the preferential use of polytetrafluoroethylene grafts for femoropopliteal bypass justified? J Vasc Surg 1988;8:219-228. 29. SHULMAN ML, BADHEY MR. Late results and angiographic evaluation of arm veins as long bypass grafts. Surgery 1982;92:1032-1041. 30. BREWSTER DC, CHARLESWORTH PM, MONAHAN JE, et al. Isolated popliteal segment vs tibial bypass. Comparison of hemodynamic and clinical results. Arch Surg 1984;119:775-779. 31. EVANS LE, WEBSTER MW, BROOKS DH, et al. Expanded polytetrafluoroethylene femoropopliteal grafts: forty-eight month follow-up. Surgery" 1981 ;89:16--22. 32. McCAULEY CE, STEED DL, WEBSTER MW. Sevenyear follow-up of expanded polytetrafluoroethylene (PTFE) femoropopliteal bypass grafts. Ann Surg 1984;199:57-60.
We have used polytetrafluoroethylene preferentially for bypasses to the above-knee popliteal artery since 1979. Since this approach has recently been challenged, we reviewed our experience with 138 grafts in 128 patients. The majority (74%) of patients were male with a mean age of 63.2 years. Risk factors included: smoking (85%), hypertension (55%), diabetes mellitus (45%), and coronary artery disease (41%). The indications for operation were disabling claudication (18%), rest pain (42%), gangrene/tissue loss (33%), and miscellaneous (7%). Perioperative (30 day) mortality was 3% and morbidity (excluding amputation or graft failure) was 5%. Patients were followed for up to eight years with a mean follow-up of 22.1 months. Grafts which remained patent, but did not prevent major amputation, were classified as "failed". Primary patency was 75% at one year and 54% at five years. Limb salvage was 88% at one year and 70% at five years. Risk factors, indication for operation and arteriographic runoff had no statistically significant impact on short- or long-term patency. However, bypass grafts to isolated popliteal segments had a significantly (p = 0.025) increased perioperative failure rate compared to all other grafts. Our data support the continued use of polytetrafluoroethylene for above-knee femoropopliteal bypass except perhaps in patients who require grafting to an isolated popliteal segment where higher early failure rates were seen. (Ann Vasc Surg 1990;4:338-343). KEY WORDS:
Extended polytetrafluoroethylene grafts; popliteal artery bypass.
Since Kunlin [1] first described femoropopliteal bypass in 1949, reversed autologous saphenous vein has remained the graft material of choice for this procedure. However, between 20 and 40% of patients requiring infrainguinal bypass grafting will not have an adequate ipsilateral greater saphenous vein [2,3]. If the surgeon is willing to use arm veins or to construct composite grafts using vein fragments harvested from multiple sites, autogenous conduits can be fashioned in a significant percentFrom the Department of Surgery, Division of Vascular Surgery and the Department of Environmental Health, Division o f Biostatistics, University of Cincinnati Medical Center, Cincinnati, Ohio. Reprint requests: Richard F. Kempczinski, MD, Department of Surgery, University of Cincinnati Medical Center, 231 Bethesda Avenue, Cincinnati, Ohio 45267-0558.
age of these patients. However, such grafts do not appear to have a long-term patency equivalent to a good, greater saphenous vein. Polytetrafluoroethylene (ePTFE) grafts were first introduced for clinical use in 1973, and early experiences [4-15] suggested patency and limb salvage rates compared favorably with saphenous vein when they were used for bypasses to the aboveknee (AK) popliteal artery. A more recent prospective study [16] has shown that the results of AK femoropopliteal bypass with expanded (ePTFE) are equivalent to those with reversed saphenous vein. The clear superiority of saphenous vein over synthetic material has been consistently demonstrated for infrageniculate grafting [9,16-18]. Our policy of preferentially using prosthetic grafts for bypass to the AK popliteal artery has 338
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several attractive, albeit theoretical, advantages, Operation is expedited in debilitated, elderly patients requiring surgery for limb salvage and the greater saphenous vein is spared for subsequent use for more distal infrageniculate bypass [19,20]. Recently, several authors have challenged these arguments and recommended that, except in very unusual circumstances, prosthetic grafts should never be used below the inguinal ligament [21,22]. To address that challenge, we reviewed our eight year experience with 138 AK ePTFE femoropopliteal grafts to evaluate both their primary patency and to establish the subsequent utilization of ipsilateral greater saphenous vein.
MATERIALS AND METHODS During the period February 1979 to November 1987, 128 patients at the University of Cincinnati Medical Center and the Cincinnati Veterans Administration Hospital underwent 138 AK femoropopliteal bypasses using ePTFE. Analysis of these patients provides the basis for this report. The majority (74%) of patients were male with a mean age of 63.2 (-+ 9.7) years. Risk factors for the development of atherosclerosis included smoking (85%), hypertension (55%,), and diabetes mellitus (45%). A history of coronary artery disease was present in 41% of patients. Bypass to achieve limb salvage accounted for the majority of procedures, with rest pain as the indication for surgery in 57 (42%,) and tissue loss or gangrene in 48 (33%). Twenty-five patients (18%) underwent operation for disabling claudication, and the remaining eight had bypasses inserted for miscellaneous indications (aneurysm, atheroemboli, etc.). Patients requiring bypass for trauma were excluded from review. All patients were categorized according to the criteria suggested by the A d H o c C o m m i t t e e on Reporting Standards [23]. Graft patency was evaluated for each category and for those patients operated on for limb salvage (i.e., all patients with rest pain or tissue loss) using the lifetable method. Arteriographic runoff was determined by review of preoperative arteriograms, and classified based upon the number of patent final vessels in direct continuity with the popliteal artery. Runoff was considered satisfactory (two or three vessel) in 66 (49%) limbs, and poor (single vessel or isolated popliteal segment) in 68 (51%). However, many of the patients with satisfactory runoff had additional occlusive lesions in the distal tibial or peroneal arteries, thus helping to explain the high percentage of our patients with critical limb ischemia. Arteriograms were unavailable for review in three patients (four limbs). Follow-up was complete for 131 patients, with only seven patients lost at varying intervals after
~, if_ ~ ~, ,~ :N ~ o ~
loo 9o 8o To
339
138
48 i
so so
38
I
24
3 YEARS
4
17 i ....
7H
40 3o 2o
lo 1
2
5
6
Fig. 1. Life table analysis: Primary patency of all grafts in this series. Numbers represent grafts at risk for each interval. Those intervals where standard error of mean was -> 10% are represented graphically by broken line.
surgery. All conclusions regarding graft patency were based on objective vascular laboratory measurements performed at regular intervals after surgery. Grafts were considered patent if the postoperative ankle/brachial index remained -> 0.01 higher than the preoperative value [23] and if calf pulse volume recordings documented graft patency [24]. If there was any question of graft status following the noninvasive studies, an arteriogram was obtained to resolve the matter. However, this was rarely necessary. No patients were placed on aspirin either pre- or postoperatively to improve graft patency. However, some of them were already taking this drug on the advice of their physicians because of cerebrovascular or cardiac disease. No .pa.t!entswere placed on Coumadin following their mmal " gralt • . Grafts that were successfully salvage d by thrombectomy, with or without revision, or those that required revision to prevent failure were classified as secondarily patent. Primary patency was calculated to the date of initial revision or failure. Major amputation was required in four patients despite a patent graft, and one functioning graft was removed because of infection. These five grafts were considered as failures for the purpose of statistical analysis. Patency data was evaluated utilizing life-table analysis [23,25],
RESULTS
Overall patency
Primary patency for all AK femoropopliteal bypass grafts using ePTFE was 75% at 12 months, 61% at three years, and 54% at five years (Fig. 1,
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TABLE I.--Life table primary patency of above-knee femoropopliteal bypass grafts with ePTFE Interval (months)
# at risk at start
Failed
0-1 1-3 3-6 6-9 9-12 12-18 18-24 24-36 36-48 48-60 60-72
138 116 110 92 76 65 48 38 24 17 7
12 4 6 7 5 5 2 4 0 1 0
*standard
Duration
Lost to Follow-up
5 1 8 6 5 9 6 7 5 7 4
2 0 3 1 0 1 0 0 0 0 0
Died
Interval patency rate
Cumulative patency (%)
SE* (%)
3 1 1 2 1 2 2 3 2 2 0
0.09 0.97 0.94 0.92 0.93 0.92 0.96 0.88 1.00 0.92 1.00
100 91 87 82 75 70 64 61 54 54 50
0.00 2.6 3.0 3.6 4.3 4.8 5.5 6.2 7.5 8.9 13.4
e r r o r of t h e m e a n
Table I). Cumulative patency (including those grafts salvaged by t h r o m b e c t o m y or local revision) was 82%, 67% and 56% for the same intervals. This difference was not significant by the logrank test at each interval. Limb salvage for those patients whose indication for surgery was rest pain or tissue loss was 88% at one year and 70% at five years (Fig. 2).
were performed on subsets representing risk factors for atherosclerosis. Either alone or in combination, diabetes, hypertension or coronary artery disease did not influence short- or long-term patency. Smoking was too ubiquitous a risk factor to effectively evaluate in this population.
Influence of arteriographic runoff Influence of operative indication and risk factors for atherosclerosis
Although the small number of patients operated upon for claudication (n = 25) makes valid statistical comparison impossible beyond one year, there appeared to be no difference in one, three, or five year patency when grafts were segregated based on surgical indications. Similar life-table and logrank test comparisons
There was no difference in early or late patency if patients with satisfactory versus poor runoff were compared. Analysis of the subgroup of patients who had bypass to an isolated popliteal segment revealed a significant (p = .025) increase in early failure rate (5 of 26 grafts) within 30 days of surgery. Despite this high early failure rate, the overall patency at three and five years for such grafts patent at discharge was comparable to grafts with satisfactory runoff.
Complications ,
.J 10% are represented graphically by broken line.
Perioperative mortality was 3.1% (4 of 128 patients), all from cardiac complications. Long-term survival (90% at 12 months, 71% at three years, and 61% at five years) was consistent with other reports [26-28]. Operative morbidity included wound complications in three (3), graft infections resulting in graft removal and revision in two (2), reexploration for bleeding in one (1), and nonfatal myocardial infarction in one (1). Twelve grafts failed within the first 30 days; two of those represented amputations despite a patent graft, one patent graft was removed for infection, and two were successfully salvaged with thrombectomy and local revision. Intermediate and late failures resulted in the loss of an additional 34 grafts for a total of 46 failures over the period of this report. One patient was lost to follow-up, 16 required major amputation, and nine had no further surgery. T w e n t y patients underwent additional recon-
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TABLE II.--Primary long-term patency of ePTFE femoropopliteal bypass grafts from comparable series in the literature
Gupta [5] (1980) Evans [31 ] (1981 ) Bergan [6] (1982) McCauley [32] (1984) Christenson [4] (1985) Sterpetti [20] (1985) Veith [16] (1986) Raggerty [26] (1987) Claudication Limb salvage Rutherford [27] (1988) Quifiones-Baldrich [28] (1988) Present series
No. of grafts 92 73 33 90 153 90 91 43 63 36* 101 * 138
Primary patency 12 36 months months N/A 83% 69% 57% 82% NA 67% 50 84% 80% 82% 64% 84% 60% 79% 52% 79% 69% 83% 75%
48% 46% 74% 61%
60 months NA NA NA 43% 76% 58% NA 29% 43% NA 63% 54%
*Above knee grafts only; NA = information not available.
structive surgery following graft failure. Nine grafts were locally revised with extension of patency of the original graft by an average of 18.4 months. Ten graft failures necessitated bypass to the below-knee (BK) level. The ipsilateral autogenous saphenous vein was available for reconstruction in five of these, and ePTFE was used in the remainder. One patient had subsequent reconstruction with a composite (ePTFE-ASV) graft and one had relief of rest pain with an extended autogenous profundaplasty using endarterectomized superficial femoral artery.
DISCUSSION Although much has been written about the use of ePTFE bypass grafts in the infrainguinal position, it is difficult to draw firm conclusions based on individual or institutional experiences. Small sample size, inadequate long term follow-up, heterogeneity of indications, and level of distal anastomosis (i.e. AK popliteal, BK popliteal, and tibial vessels) all preclude valid comparisons and statistically significant conclusions. Our experience with 138 AK popliteal ePTFE bypass grafts represents one of the largest reported in the literature, with follow-up of sufficient numbers of patients for at least 60 months to provide statistically valid data. The patency rates of 75% at one year, 6t% at three years, and 54% at five years compare favorably with other similar reports (Table II). Indication for operation and arteriographic runoff have previously been reported to significantly influence the long-term patency of infrainguinal bypass grafts [18]. This contrasts with our findings, and those of others, which failed to demonstrate any difference in either short- or long-term patency based on indication (claudication, rest pain or tissue loss) [28] or arteriographic runoff [29]. Only in that
small subset of patients who underwent bypass to an isolated popliteal segment could any difference in early graft failure be demonstrated. The high (19%) early failure rate of those grafts appeared to be more a consequence of surgical optimism, i.e., attempting to revascularize a limb that was probably unsalvageable. Our three year patency of 65% for ePTFE grafts to the isolated popliteal arterial segment suggests that such bypasses perform acceptably over the long-term in appropriate patients. Quifiones-Baldrich and associates [29] recently reviewed a similar experience with 146 femoropopliteal ePTFE grafts of which 101 were above-knee. Their five-year patency for AK grafts (63%) was statistically comparable to our results despite the fact that more than half (55%) of their patients underwent operation for intermittent claudication compared to only 18% of our patients. They also found similar patency rates with both good and poor runoff. The well-documented poor performance of prosthetic vascular grafts when used for bypass to the infrageniculate popliteal artery and tibial vessels has convinced most vascular surgeons of the necessity to use autogenous grafts for reconstructions in this position. However, a patient presenting with graft thrombosis several years after an AK reconstruction with reversed saphenous vein represents a much more difficult reoperative challenge than does a similar patient in whom the saphenous vein has been previously spared. Composite autologous grafts with vein harvested from the contralateral leg (which frequently has a compromised arterial supply as well), the arm, or from the ipsilateral lesser saphenous system may not have the same good long term patency rates that have been reported with in-situ techniques [29]. Thus, given the satisfactory patency which we have achieved using ePTFE grafts in the AK position, the preferential use of this
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material has theoretic appeal for the preservation of saphenous vein for later reconstruction. In a review of 59 AK prosthetic reconstruction, Rosen and colleagues [19] identified eight patients (14%) who required subsequent below-knee in-situ bypass grafts. They compared this group of patients against those having an initial in-situ bypass below the knee (n = 75). At 36 months, the cumulative limb salvage rate for staged reconstructions (prosthetic followed by in-situ) was 87%, compared to 73% and 78%, respectively, for prosthetic and insitu alone. More importantly, of 14 prosthetic grafts that occluded within the study period, 10 (71%) had an available saphenous vein which could have been utilized for distal reconstruction. This contrasts with those patients undergoing in-situ grafting as the initial procedure. In this group, 11 of 16 grafts that failed resulted in a limb loss. Our data also support the concept of performing an initial AK popliteal bypass with ePTFE, thus preserving the saphenous vein for later use as an infrageniculate bypass. Of the 10 graft failures in our series which required bypass to the below-knee level, autogenous saphenous vein was available for in-situ reconstruction in five. One additional patient had reconstruction with a composite (ePTFE-ASV) graft. Because we have become more aggressive with distal reconstruction using the in-situ technique, the availability of ipsilateral vein permits us to revascularize patients with disadvantaged outflow tracts following failure of an AK bypass who would have previously come to amputation. When presented with a patient who has an isolated AK popliteal segment and reconstitution of a distal tibial artery, we select our initial bypass based on the indications for surgery. In patients presenting with gangrene or tissue loss on the forefoot, the restoration of pulsatile flow to this level appears to be critical for optimal success [30], and we would perform a bypass to the tibial vessel which communicates most directly with the pedal arch using autogenous vein. However, for the relief of rest pain we would perform a bypass with ePTFE to the AK popliteal artery. Our low early failure rate (6.7%) and high three year patency (73%) in the group of patients with rest pain and an isolated popliteal segment clearly supports this approach. The higher early failure rate of prosthetic grafts to an isolated AK popliteal segment was primarily in patients undergoing bypass for advanced gangrene with no distal reconstructible vessel. Although the long-term patency rate of 65% at three years is acceptable in this subset of patients, there is no theoretic advantage to preserving the autogenous saphenous vein. In this group, we now recommend primary bypass with ASV.
ACKNOWLEDGMENT The authors wish to express their appreciation to Rosalie Bodenham, RN, for her invaluable assistance in the collection of the data reported in this manuscript.
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