Creation of a distal arteriovenous fistula improves microcirculatory hemodynamics of prosthetic graft bypass in secondary limb salvage procedures

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1 ORIGINAL ARTICLES Creaton of a dstal arterovenous fstula mproves mcrocrculatory hemodynamcs of prosthetc graft bypass n secondary lmb salvage procedures Mchael J. H. M. Jacobs, MD, George J. Reul, MD, Igor D. Gregorc, MD, Drk Th. Ubbnk, MD, Jan H. M. Tordor, MD, Peter J. E. H. M. Ktslaar, MD, and Robert S. Reneman, MD, Maastrcht, The Netherlands, and Houston, Texas Purpose: In patents wth crtcal lmb schema, poor dstal arteral runoff, and absence of autogenous vens, the use of an artfcal graft and an arterovenous fstula mght be a valuable opton. However, n these patents lttle nformaton s avalable regardng preoperatve and postoperatve mcrocrculatory hemodynamcs after ths type of nterventon. Methods: Wth the use of ntravtal capllary mcroscopy, we studed the effect of dstal revascularzaton on the mcrocrculaton n 26 patents wth crtcal lmb schema. All patents had had faled vascular reconstructve operatons, and artfcal grafts were requred because of the absence of autogenous vens. Patents were prospectvely nvestgated and dvded nto two groups: 12 patents receved a femorocrural bypass wth polytetrafluoroethylene grafts, and 14 patents underwent the same procedure wth the creaton of an arterovenous fstula at the ste of the dstal anastomoss and lgaton of the proxmal ven. Red blood cell velocty was measured before and after arteral occluson to determne mcrocrculatory hemodynamc alteratons. Results: Immedate postoperatve graft patency was acheved n all 26 patents. The 1-year cumulatve graft patency rate was 64% n the group that had creaton of an arterovenous fstula, whch was sgnfcantly hgher (p < 0.01) compared wth that n the group n whch a fstula was not created (21%). The 1-year cumulatve foot salvage rate was 72% n the patents wth an arterovenous fstula and 43% n the patents wthout a fstula (p < 0.05). Red blood cell velocty ncreased smlarly n both groups after the bypass procedure. Peak and tme to peak red blood cell velocty also mproved sgnfcantly n both groups; however, comparng both groups, peak and tme to peak red blood cell velocty were sgnfcantly better (p < 0.05) n the patents wth an arterovenous fstula and remaned sgnfcantly hgher durng the follow-up perod. Conclusons: In concluson, creaton of an adjunctve arterovenous fstula at the dstal anastomoss of a prosthetc graft appears to mprove mcrocrculatory hemodynamcs n the nutrtonal capllary vascular bed. Improved graft patency and foot salvage rates suggest that ths procedure benefts patents wth crtcal lmb schema who have no usable vens. (J VAsc SURG 1993;18:1-9.) From the Dvsons of Vascular Surgery, Academc Hosptal Maastrcht and CARIM, The Netherlands, and Texas Heart Insttute/St. Luke's Epscopal Hosptal (Drs. Reul and Gregotc), Houston. Presented at the Sxteenth Annual Meetng of the Southern Assocaton for Vascular Surgery, St. Thomas, Vrgn Islands, Jan , Reprnt requests: Mchael J. H. M. Jacobs, MD, Department of Surgery, Academc Hosptal Maastrcht, PO Box 5800, 6202 AZ Maastrcht, The Netherlands. Copyrght 1993 by The Socety for Vascular Surgery and Internatonal Socety for Cardovascular Surgery, North Amercan Chapter /93/$ /6/41521 In patents wth crtcal lmb schema the autogenous ven bypass to the nfrapoplteal vessels s a well-accepted procedure wth satsfactory patency rates) Bypasses performed wth polytetrafluoroethylene (PTFE) are wdely regarded as beng of questonable value. 2,3 However, wth the use of peroperatve heparn and postoperatve warfarn, the patency of nfrapoplteal PTFE grafts seems to mprove. * Furthermore, n the absence of a ven, a PTFE tbal bypass s a better opton than a prmary amputaton, because the former has a 1-year graft

2 2 Jacobs et al. july 1993 A mm 2ram Fg. 1. Surgcal technque of creaton ofarterovenous fstula n whch graft s anastomosed to common ostum and proxmal ven s lgated. Cross sectons are shown at level of graft (A) and at anastomoses (B). patency rate of 40% and a 5-year foot-salvage rate of up to 60%. 5 Recently, the European Consensus Document on crtcal leg schema recommended that prosthetc grafts should only be used wth adjunctve procedures such as an arterovenous fstula or a ven cuff. 6 Ths recommendaton s based on retrospectve studes that sgnfed mproved graft patency and foot salvaget,8; however, ths mprovement s not evdenced by prospectve randomzed trals. In a recent study we found an ncreased graft patency rate wth the use of a prosthetc graft and a dstal arterovenous fstula wth lgaton of the proxmal ven. 9 Possble mechansms responsble for the mproved patency have been nvestgated n several hemodynamc anmal experments; however, most studes showed nconclusve results, l,n No nformaton s avalable regardng the nfluence of dstal reva~cularzaton wth or wthout an adjunctve arterovenous fstula on mcrocrculatory hemodynamcs. Wth the use of ntravtal capllary vdeo mcroscopy, we studed the effect of dstal bypass procedures on the mcrocrculaton n 26 patents wth crtcal lmb schema who receved a femorocrural bypass wth a PTFE graft or the same procedure wth the creaton of an arterovenous fstula. PATIENTS AND METHODS Between January 1990 and November 1991, 26 patents (16 men and 10 women) were enrolled n the study and underwent PTFE femorocrural bypasses for the treatment of rest pan (62%) or tssue necross (38%). The usual rsk factors were observed, wth dabetes beng present n 42% of patents, coronary artery dsease n 56%, prevous myocardal nfarcton n 38%, and hypertenson n 48%. Thrty-four percent of the patents were actvely smokng at the tme of operaton and 58% had been smokers wthn the 10-year perod precedng the procedure. Patents ranged n age from 38 to 91 years, wth a mean of years. All patents had had faled vascular reconstructon of the nvolved lmb (range one to fve procedures; mean 1.5). Selectve angography revealed longsegment occluson of the superfcal femoral artery n all patents wth reconsttuton of only one runoff crural artery. Proxmal anastomoses were placed at the common femoral artery n all patents. The dstal anastomotc stes ncluded the posteror tbal (46%), anteror tbal (31%), and peroneal (23%) arteres. Because of prevous coronary and perpheral vascular bypass procedures, no autogenous saphenous ven grafts were avalable, and PTFE, 6 mm dameter,

3 IOURNAL OF VASCULAR SURGERY Volume 18, Number 1 Jacobs et al. 3 6mm (: 0 2mm Fg. 2. Technque of dstal end-to-end anastomoss wthout arterovenous fstula. Cross sectons are shown at level of graft (A) and at dstal anastomoss (B). Note oval taperng as result of dscrepancy of graft and artery dameters. thn-walled, rnged Gore-Tex* grafts were used n all patents. Because age, sex, rsk factors, number of faled reconstructons, and the dstal anastomotc stes were evenly dstrbuted among the two groups, patents were randomly dvded nto two groups before operaton, on the bass of the surgcal procedure: 12 patents receved a femorocrural bypass and 14 patents underwent the same procedure wth the creaton of an onlay arterovenous fstula. Operaton was performed wth general anesthesa and heparn (1 mg/kg) was admnstered ntravenously before cross-clampng. All patents receved antbotc prophylaxs (cefuroxme) for 24 hours and were treated wth coumarn durng the follow-up after operaton. The surgcal technque of the creaton of the arterovenous fstula has been descrbed n detal. 9 In summary, the arterotomy n the crural artery was followed by a venotomy n the vena comtans, both 15 to 20 mm long. The adjacent walls were anastomosed n a sde-to-sde fashon wth a 7-0 polypro- ~Gore-Tex s a regstered trademark of W.L. Gore & Assocates, Inc., Flagstaff, Arz. pylene suture to create a common posteror wall. The PTFE graft was then anastomosed end to sde to the common ostum (Fg. 1). To prevent venous shuntng the ven was lgated 2 to 3 mm proxmal to the fstula. In the group of patents wthout a fstula, the PTFE graft was anastomosed end to sde to the crural artery n the usual fashon (Fg. 2). Intraoperatve angography was performed routnely to permt vsualzaton of the dstal anastomoss and the runoff n the lmb and foot. Follow-up ranged from 0 to 24 months wth a mean of 8 months. In both groups one patent was lost to follow-up. Patency rates, foot salvage, and operatve ndcatons were all defned accordng to the standards proposed by the Ad Hoc Commttee on Reportng Standards. 12 Contnuous-wave Doppler examnatons and duplex scannng studes were performed at 3-month ntervals to assess graft patency or earler f graft patency was questonable. In all patents, the ankle/arm pressure ndex and the mcrocrculatory parameters were determned before operaton, wthn 10 days after operaton, and at the last follow-up.

4 IOURNAL OF VASCULAR SURGERY 4 Jacobs et al. luly 1993 CAME D I VIDEO RECORDER ANALYSIS SYSTEM MONITOR <] LISHT SOURCE Fg. 3. Schematc setup of ntravtal capllary vdeo mcroscopy. Capllary mcroscopy s an accepted nonnvasve technque to measure nutrtve skn perfuson. 13 The method yelds reproducable nformaton as to the morphologc condton and dynamcs of skn capllares and provdes addtonal nformaton n patents wth crtcal schema. Intravtal capllary mcroscopy was performed after 20 mnutes of acclmatzaton n a sttng poston n a room wth a constant temperatnre between 23 and 24 C. Patents were subjected to capllary mcroscopy of the nal fold of the great toe, the technque of whch has been descrbed n detal before. 14 The foot of the patent was postoned at the stage of the mcroscope and fxated n a mass of clay. The nal fold was covered wth a drop of paraffn ol to mprove skn transparency. Capllares were vsualzed wth a modfed Letz mcroscope (Letz GmbH, Wetzler, Germany). The mages were produced on a montor screen and stored on tape for off-lne analyss wth the use of a vdeocassette recorder. A schematc drawng of the system s presented n Fg. 3. From the stored vdeo mages the followng parameters were assessed n three capllares: 1. The number of erythrocyte-perfused capllares per square mllmeter of nal fold skn (densty) 2. Red blood cell (RBC) column wdth n the arterolar lmbs oft_he capllary loops n mcrometers representng the dameter 3. RBC velocty at rest, as measured wth a flyng spot devce, 15 expressed n mcrometers per second (RBC velocty s assessed by synchronzng the movng spots wth the blood cells and plasma gaps n the arterolar branch of the capllary.) 4. Peak RBC velocty durng reactve hyperema after a 1-mnute arteral occluson nduced by nflatng a cuff around the ankle (Ths arteral occluson s the provocaton test to cause the reactve hyperemc response.) 5. Tme to peak RBC velocty n seconds as the tme needed to reach peak velocty after release of the cuff The average values of the measurements were taken as the readngs for the patents. The statstcal analyss of the dfferences n mcrocrculatory results between patents wth and wthout an arterovenous fstula was performed by means of the nonparametrc Mann-Whtney U test. Dfferences between preoperatve and postoperatve results were tested by use of the Wlcoxon sgnedrank test. The follow-up survval data were produced wth the SPSS statstcal package (verson 4.0 Manual 1990; SPSS Inc., Chcago, Ill.), whch contans the

5 Volume 18, Number 1 Jacob# et al ~ - 80 I lo 2 12 = 10 9 wth AV fstula.... O I, e,, ().... O.... O.... O.... O.... O I O.... O.... O.... O.... O wthout AV fstula ; ~ I I I I I I t I I I Months Fg. 4. Lfe-table analyss of cumulatve foot salvage rate. AV, Arterovenous , ?, J 10 12,,,, O.... O 8 ', O.... O.... O e,, 8 wth AV fstula, wthout AV fstula O.... O O.... O ,o ' &... o...? 3,3, I I I I I I I I I I I Months Fg. 5. Lfe-table analyss of cumulatve graft patency rate. AV,, Arterovenous. Lee-Desu statstc for overall comparson of the two survval curves. RESULTS No deaths occurred wthn 30 days after the operatve procedure, and graft patency was acheved n each patent n the mmedate postoperatve perod. Fve superfcal wound nfectons occurred, whch dd not requre operatve debrdement. The mean ankle/arm pressure ndex ncreased from 0.28 _ preoperatvely to postoperatvely (p < 0.01). In the arterovenous fstula group, four grafts occluded after 2, 5, 6, and 10 months, respectvely. Thrombectomy was performed n all patents, however, below-knee amputaton was necessary n three patents, whch accounted for a cumtflatve foot salvage rate of 72% after 2 years. It should be emphaszed that the standard error exceeds 10% after 5 months of follow-up (Fg. 4). The cumulatve graft patency rate was 64% after 1 year, agan wth a standard error exceedng 10% after 5 months (Fg. 5). Durng the second year of followup, all grafts wth an arterovenous fstula remaned patent; however, only seven patents were at rsk.

6 6 Jacobs et al. July 1993 All data on foot salvage and graft patency are presented wth lfe-table analyss untl 12 months of follow-up, because no changes occurred durng the second year. In the group of patents wth a PTFE graft wthout an arterovenous fstula, nne grafts occluded. Four grafts thrombosed n the second month, two grafts occluded n the thrd month, and three grafts faled after 4, 7, and 9 months, respectvely. Thrombectomy and revson of the anastomoses was performed n eght of the nne patents wthout successful outcome. Four patents underwent above-knee and two patents underwent belowknee amputaton. The cumulatve foot salvage rate after 1 year was 43% (Fg. 4). Because of the small group and early occlusons, the standard error already exceeded the 10% lmt after 1 month. The cumulatve graft patency rate (Fg. 5) after 1 year was 21%. The overall comparson n both groups showed a statstcally sgnfcant (p < 0.05) hgher foot salvage rate n the patents wth an arterovenous fstula (Fg. 4). The graft patency rate was sgnfcantly (p < 0.01) hgher n the patents wth an arterovenous fstula (Fg. 5). The ankle/arm pressure ndexes and mcrocrculatory data were measured for both groups before operaton, wthn 10 days after operaton, and at the last follow-up (Table I). The ankle/arm pressure ndex was sgnfcantly hgher n the arterovenous fstula group at the last follow-up. Capllary densty mproved sgnfcantly wthn each group after operaton, -whch showed that the revascularzaton mproved the capllary nutrtonal perfuson area. There were no dfferences between both groups, although n the arterovenous fstula group the capllary densty remaned sgnfcantly hgher as compared wth the ntal values. RBC velocty mproved after operaton; however, there were no dfferences between the two groups at short- and long-term follow-up. Peak RBC velocty and tme to peak RBC velocty mproved sgnfcantly mmedately after operaton wthn each group; however, n a comparson of both groups, peak RBC velocty and tme to peak RBC velocty were sgnfcantly better n the patents wth an arterovenous fstula as compared wth the values n patents wthout an arterovenous fstula. Durng follow-up, peak and tme to peak RBC velocty returned to the basc values n the group wthout an arterovenous fstula, whereas n the patents wth arterovenous fstula, these values remaned sgnfcantly hgher. DISCUSSION In patents wth crtcal lmb schema, poor dstal arteral runoff, and absence of autogenous ven, the use of prosthetc graft materal for lmb salvage s stll questonable. The 1-year patency rate of 40% and 5-year foot salvage rate of 60% suggest that PTFE grafts to the tbal vessels are a valuable opton when no ven s avalable, s The dea for usng dstal arterovenous fstulas s based on ncreased flow velocty along the whole graft exceedng the crtcal thrombotc threshold level. The mprovement that has been observed remans unproven, because no prospectve randomzed studes have been performed that compare dstal prosthetc grafts wth and wthout an arterovenous fstula. 7,8 Several studes nvestgatng the clncal results of an adjunctve arterovenous fstula report acceptable patency and foot salvage rates, 16 especally when shorter grafts are used and occlusve dsease n the pedal arteres s lmted, a7ls Snyder et al. 19 however, only found augmented graft flow n the mmedate postoperatve perod and low long-term patency rates. In the present study all patents had crtcal schema, sngle crural vessel runoff, and no autogenous ven. Graft patency and foot salvage rates were sgnfcantly hgher when prosthetc grafts were used wth an adjunctve arterovenous fstula, as compared wth results when a prosthetc graft was used wthout a fstula. Although the number of patents was small n both groups, the sgnfcant dfferences n clncal outcome could be confrmed by the objectve measurement, both on short- and long-term follow-up. Before operaton the ankle systolc pressures were smlar n both groups, and they ncreased sgnfcantly after operaton. At the last follow-up the better graft patency was confrmed by the sgnfcantly hgher ankle/brachal ndex n the patents wth an arterovenous fstula. In both groups, morphologc capllary mcroscopy showed no changes n capllary dameter after operaton. In both groups, capllary densty mproved sgnfcantly, whch ndcated enhanced total nutrtonal capllary perfuson. At the last follow-up, capllary densty returned to the ntal values n patents wthout a fstula and remaned hgh n the patents wth a fstula. Preoperatve RBC velocty was comparable n both groups and mproved sgnfcantly after operaton. Inducng a reactve hyperemc response caused sgnfcant changes between both groups. Peak and tme to peak RBC velocty mproved sgnfcantly n both groups, beng sgnfcantly better n the patents wth an

7 Volume 18, Number 1 Jacobs et al. 7 Table I. Macrocrculatory and mcrocrculatory data before operaton, after operaton, and at the last follow-up PTFE wthout PTFE wth Medan values arterovenous fstula Mann- Whtney arterovenous fstula ABI Before 28 ] NS 28]] After 79 ~ NS 84 ~ Follow-up 28 p < J** Densty Before 30] NS 35]] After 48 ~ NS 51 ~* Follow-up 26 NS 48 Dameter Before 8 NS 8 After 9 NS 8 Follow-up 8 NS 8 RBCV Before 33] NS 50]] After 140 ~ NS 252 ~ Follow-up 68 NS 98 J PRBCV Before 48] NS 79]] After 248 ~ p < ~ Follow-up 70 p < J~ TPRBCV Before 44] NS 41 ] ] After 18 ** p < ~ Follow-up 48 p < J** ABI, Ankle/brachal ndex; NS, not sgnfcant; RBCV~ red blood cell velocty; PRBCV, peak red blood cell velocty; TPRBCV, tme to peak red blood cell velocty. *p < 0.05; **p < arterovenous fstula as compared wth values n patents wthout an arterovenous fstula. Durng the follow-up perod, capllary mcroscopy allowed objectve evaluaton of the clncal outcome. In the patents wth an arterovenous fstula, RBC velocty, peak RBC velocty, and tme to peak RBC velocty remaned sgnfcantly hgher as compared wth the values n the patents wthout an AV fstula. Also the ndvdual data showed that mcrocrcuatory blood flow correlated wth the patency of the graft. In both groups of patents an open graft always nduced mproved capllary hemodynamcs, and n all cases an occluded bypass resulted n compromsed mcrocrculatory blood flow. These fndngs ndcate the applcablty of ntravtal capllary mcroscopy n the evaluaton of skn mcrocrcnlaton n patents wth crtcal schema who undergo dstal bypass operaton. In our technque we lgate the proxmal ven to prevent venous shuntng, a concept that s open to debate. In an expermental study, McGovern et al?0 showed that the anastomotc arterovenous fstula leads to rapd reversal of flow n the dstal artery and the development of venous hypertenson. Other studes showed ncreased graft blood flow, ether wth placement of the graft dstal to the adjunctve arterovenous fstula 11 or wth a remote arterovenous lcstula. 16 In a large seres of patents, Dardk et al.s have shown prograde flow n the dstal arteral crcut, and ther data ndcate that total flow nto the venous crcut and dstal arteres s sustaned by the ncreased volume and velocty nduced by those grafts constructed wth an adjunctve arterovenous fstula. Wth the ven left open, turbulent flow wll exst and wll be maxmal at the dstal anastomoss, because the blood flow s dverted n opposte drectons: dstally to the artery and proxmally to the ven. A reason responsble for the hgher patency rate n the patents wth an arterovenous fstula mght be the larger anastomoss and therefore delayed obstructon by fbrontmal hyperplasa. Wth the fstula, the crosssecton of the dstal anastomoss s crcular (Fg. 1), n contrast to the ncongruous anastomotc confguraton of the 6 mm graft and the 2 to 3 mm artery (Fg. 2). In concluson, creaton of an adjunctve artero-

8 8 Jacobs et al July 1993 venous fstula at the dstal anastomoss of a prosthetc graft mproves mcrocrculatory hemodynamcs n the dstal nutrtonal capllary vascular bed. Improved graft patency and foot salvage rates suggest that ths procedure mght be a valuable opton n the treatment of patents wth crtcal lmb schema, poor arteral run-off, and no usable autogenous ven. To valdate ths statement, a prospectve randomzed study should be performed that compares prosthetc graft bypasses wth and wthout an arterovenous fstula. REFERENCES 1. Taylor LM, Edwards JM, Porter jim. Present status of reversed ven bypass: fve-year results of a modern seres. J VAsc SURG 1990;11: Denns JW, Lttooy FN, Gresler HP, Baker WH. Secondary vascular procedures wth polytetrafluoroethylene grafts for lower extremty schema n a male veteran populaton. J VAsc SukG 1988;8: Qunones-Baldrch WJ, Busuttl RW, Baker JD. Is the preferental use of polytetrafluoroethylene grafts for femoropopllteal bypass justfed? J VASC SURG 1988;8: Fllnn WR, Rohrer MJ, Yao JST, et al. Improved long-term patency of nfragencular polytetrafluoroethylene grafts. J VASC SURG 1988;7: Veth FJ, Grupta SK, Ascer E, et al. Sx-year prospectve multcenter randomzed comparson of autologous saphenous ven and expanded polytetrafluoroethylene grafts n nfrangunal arteral reconstructons. J VAse SUV, G 1985;3: European Workng Group on Crtcal Leg Ischema. Second European Consensus Document on chronc crtcal leg schema. Crculaton 1991;84(suppl 4): Mller JH, Foreman RK, Ferguson L, Fars I. Interposton ven cuff for anastomoss n prosthetc to small arteres. Aust N Z J Surg 1984;54: Dardk H, Berry SM, Dardk A, et al. Infrapoplteal prosthetc graft patency by use of the dstal adjunctve artetovenous fstula. J VASE SVRG 1991;13: Jacobs MJHM, Gregorc I, Reul GJ. Prosthetc graft placement and creaton of a dstal arterovenous fstula for secondary vascular reconstructon n patents wth severe lmb schema. J VASC SURG 1992;15: McGovem PJ Jr, Jan KM, Kerr JC, Swan KG, Rockol JM. Hemodynamcs of an anastomotc arterovenous fstula. Am J Surg 1985;149: Parvn SD, Bentley S, Asher MJ, Prytherch DR, Evans DH, Bell PRF. Haemodynamcs of the adjunctve arterovenous fstula n femorodstal bypass graftng: an expermental study. Br J Surg 1984;71: Rutherford RB, Flangen DP, Gupta SK, et al. Suggested standards for reports dealng wth lower extremty schema. J VASC SURG 1986;4: Jacobs MJHM, Ubbnk DTh, Ktslaar PJEHM, Tordor JHM, Slaaf DW, Reneman RS. Assessment of the mcrocrculaton provdes addtonal nformaton n crtcal lmb schaema. Eur J Vasc Surg 1992;6: Jacobs MJHM, Breslau PJ, Slaaf DW, Reneman RS, Lemmens HAJ. Nomenclature of Raynaud's phenomenon: a capllary mcroscopc and hemorrheologc study. Surgery 1987;101: Tyml K, Ells CG. Evaluaton of the flyng spot technque as a televson method for measurng red cell velocty n mcrovessels. Int J Mcrocrc Cln Exp 1982;1: Paty PSK, Shah DM, Saf J, et al. Remote dstal arterovenous fstula m mprove nfrapopllteal bypass patency. J VAsc SURG 1990;11: Moody AP, A1Fagh S, Edwards PR, Campbell H, Harrs PL. The use of an adjuvant artero-venous shunt n prosthetc femoro-crural bypass. Eur J Vasc Surg 1991;5: Harrs PL, Campbell H. Adjuvant dstal arterovenous shunt wth femorotbal bypass for crtcal schaema. Br J Surg 1983;70: Snyder SO, Wheeler JR, Gregory RT, Gayle RG. Falure of atterovenous fstulas at dstal tbal bypass anastomotc stes. J Cardovasc Surg 1985;26: Submtted Jan. 27, 1992; accepted Aug. 3, DISCUSSION Dr. Jock R. Wheeler (Norfolk, Va.). In procedures such as have been descrbed here there s no consensus concernng fstula constructon, nor s there agreement over the effcacy of ths procedure n mprovng long-term graft patency and lmb salvage. It s nterestng to me to note, as one of my former colleagues mentoned, that we have been dscussng ths problem for 15 years. Dr. Jacobs and hs colleagues have provded us wth a unque method of objectvely assessng the physologc effects of an adjuvant arterovenous fstula. Ther data not only lend support to the valdty of ths procedure but may provde us wth a better understandng as to why some patents do well wth the fstulas and others do not. Although ther seres s small, ther results at 1 year wth a cumulatve patency rate of 64% and a lmb salvage rate of 72% n the arterovenous fstula group s mpressve, especally wth the use of the straght PTFE graft. In contrast, Dr. Stan Snyder reported our seres some years ago wth less than encouragng results. In a revew of our experence wth 30 femorotbal bypasses and creaton of a dstal arterovenous fstula at the dstal anastomoss by the common osteal technque, we observed a dsappontngly low graft patency rate wth four out of the 30 grafts beng patent at the end of 22 months of follow-up. Lmb salvage was acheved n sx of the patents at 22 months. All of the patents had an ncomplete pedal arch and all underwent operaton for lmb salvage. Poor graft patency and lmb salvage results were found

9 Volume 18, Number 1 Jagob$ ctal. 9 despte a hgh ntal fstula patency rate of 97% and a hgh ntal mean graft flow rate of 260 ml/mn. In the sx lmbs salvaged three grafts were patent despte an occluded fstula. In two cases both the fstula and the graft thrombosed, and only one case had a patent fstula and patent graft. As a result of these fndngs, we concluded that the addton of the arterovenous fstula n femoral dstal bypasses offered no sgnfcant clncal beneft over the standard bypass procedure. I have two questons and several thoughts for the authors, and despte our skeptcsm we are mpressed by the data that were presented today. It s apparent when I look at the dagram that, when the authors llgate the proxmal fstula, leavng competent valves on the dstal sde, ths may be lttle more than a dstal patch such as a Lnton patch wth a PTFE graft placed on that, and I wsh Dr. Jacobs would comment on ths. There would be some small amount of runoff n that area from small venous trbutares. Also, I would lke to ask the author whether the severty of pedal dsease affected the results, gven that capllary mcroscopy was routnely performed on the great toe. Dr. Mchael J. H. M. Jacobs. Regardng the possblty of runoff through the sde branches of the ven, we beheve that even wth competence of the valves n the ven there s some runoff, and on angograms we performed some 6 or 8 months after the procedure we fotmd that through the ven n the antegrade drecton there s outflow through the sde branches. So ths defntely wll contrbute to the hemodynamcs. As concerns the capllary mcroscopy, n the ntal stage we dd not see the dfferences between both groups and t was the frst am of the study to see whether there would be dfferences n the mcrocrculaton n the short term. And n the short term there were no dfferences durng restng condtons; only after arteral occluson, that s, durng reactve hyperema, dd we observe dfferences. BOUND VOLUMES AVAILABLE TO SUBSCRIBERS Bound volumes of the JOURNAL OF VASCULAR SURGERY for 1993 are avalable to subscrbers only. They may be purchased from the publsher at a cost of $69.00 for domestc, $89.83 for Canadan, and $85.00 for nternatonal subscrbers for Vol. 17 (January to June) and Vol. 18 (July to December). Prce ncludes shppng charges. Each bound volume contans a subject and author ndex, and all advertsng s removed. Copes are shpped wthn 60 days after publcaton of the last ssue n the volume. The bndng s durable buckram wth the journal name, volume number, and year stamped n gold on the spne. Payment must accompany all orders. Contact Subscrpton Servces, Mosby, Westlnc Industral Dr., St. Lous, MO , USA. In the Unted States call toll free (800) , ext In Mssour or foregn countres call (314) Subscrptons must be n force to qualfy. Bound volumes are not avalable n place of a regular JouRNAL subscrpton.