Comparison of basilic vein polytetrafluoroethylene for arteriovenous fistula. and brachial

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1 Comparison of basilic vein polytetrafluoroethylene for arteriovenous fistula and brachial Michael C. Coburn, MD, and Wilfred I. Carney, Jr., MD, Providence, R.L Purpose: The aim of this study was to compare patency and complication rates between basilic vein and polytetrafluoroethylene (PTFE) for brachial arteriovenous fistulas (AVF) for long-term hemodialysis. Methods: All basilic vein and PTFE brachial AVF constructed between March 1988 and April 1993 were retrospectively reviewed. After construction of life-tables, log-rank testing was used to compare the primary patency rate of basilic vein AVF (n = 59) with the primary and secondary patency rates ofptfe AVF (n = 47). Complication rates were calculated for each type of fistula and compared by use of chi-squared testing. Results: The primary patency rate for basilic vein AVF (9%) was superior to that of PTFE AVF (7%) at 1 year (p <.1), and at 2 years (86% vs 49%,p <.1). Complications occurred two and a half times more fi~equently in the PTFE group than in the basilic vein group (p <.5). Conclusions: Basilic vein AVF provided superior patency rates and lower complication rates compared with PTFE AVF. Prospective randomized trials comparing the two fistula types is required to firmly establish the basilic vein AVF as the alternative access procedure of choice after a failed or unconstructable radiocephalic fistula. (J VASC SURG 1994;2: ) The radial artery-cephalic vein fistula of Brescia and Cimino 1 remains the uncontested access of first choice for long-term hemodialysis. Nevertheless, most patients undergoing long-term hemodialysis will either lack adequate vein for construction or have development of an unsalvageable thrombosis of such a fistula. 2,a Hence, an alternative access site is commonly required. This alternative has typically invoked the use of prosthetic materials, as Upper extremity access with use of polytetrafluoroethylene (PTFE) has proven valuable, but patency rates are lower and complications rates higher than with the Brescia-Cimino fistulas, a,4,6 Recently there has been a renewed interest in the use of the brachial artery-basilic vein fistula, first proposed by Dagher et al. 7 Two-year patency rates of 7% to 8%, with relatively few complications, are From the Department of Surgery, Rhode Island Hospital and Brown University Providence. Presented at the Eighth Annual Meeting of the Eastern Vascular Society, Montrdal, Qudbec, Canada, May 12-15, Reprint requests: Wilfred I. Carney, Jr., MD, I1 Lockwood St., Physician's Office Building, Providence, RI 293. Copyright 1994 by The Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter /94/$ /6/ now being published. 8~ However, a direct comparison between the brachial artery-basilic vein fistula and upper extremity shunts with PTFE has not been performed. Hence, this retrospective study comparing patency and complication rates between the brachial artery-basilic vein and upper extremity PTFE fistulas for hemodialysis was conducted to address this issue. MATERIAL AND METHODS All patients who underwent construction of either a brachial artery-basilic native vein fistula (BAVF) or an upper extremity PTFE fistula (PTFEF) for long-term hemodialysis between March 1988 and April 1993 at a single institution were identified by an office-based computer system. Approximately 9% of the primary and revisionary procedures involving both BAVF and PTFEF were performed by the senior author (W. I. C.). For the purposes of the study, radial artery--cephalic vein and radial artery-antecubital vein fistulas (i.e., forearm fistulas of native vein or prosthetic material) were ignored. Inpatient/outpatient records and office charts were reviewed, and the following information was collected: age and sex of the patient, medical history, and type(s) of grafts created. Operative data

2 Volume 2, Number 6 Cob'urn and Carney 897 Table I. Demographic data Table II. Complications Basilic vein PTFE Badlic vein PTFE Total fistulas Mean age Sex Male 3 (51)* 15 (32) Female 29 (49) 32 (68) Medical history CAD 29 (49) 2 (44) PVD 26 (46) 13 (27) DM 28 (48) 2 (44) CAD, Coronary artery disease; PVD, peripheral vascular disease; DM, diabetes mellitus. *Numbers in parenthesis are percentages. were taken directly from the anesthesia and operative record. Follow-up information was obtained by inpatient/outpatient records, office charts, and telephone conversation with referring physicians, dialysis personnel, and individual patients. These data consisted of the following: survival status, fistula patency in months, and the development of aneurysmal, bleeding, infective, and arterial steal complications. Follow-up was complete in all but one patient until time of death or July Primary patency was defined as that length of time from the grafts creation until the development of thrombosis or a complication that required operative revision of the graft. If the graft could be salvaged by thrombectomy or revision such that blood flow was maintained through most of the graft and at least one anastomosis, then the fistula was considered secondary patent. Life-table analysis figures were constructed, and patency rates between BAVF and PTFEF were compared. Complication rates between the two types of grafts were also compared. Analysis ofpatency and complication rates between the two groups of shunts was performed separately for male and female patients. Last, among BAVF, patency and complication rates were compared between women and men. Comparison of patency rates based on life-tables was performed with log-rank statistical analysis. Demographic differences and complication rates between groups were compared with use of chi-squared testing. Anatomy and surgical technique. The basilic vein is the tflnar end of the venous arch of the dorsum of the hand, and it ascends along the ulnar border of the forearm. It then receives the median cubital vein and continues up in the medial bicipital groove. It pierces the brachial fascia just below the middle of the arm. It then parallels the course of the brachial artery Infection 2 (3.4)* 1 (16.1) Arterial steal 2 (3.4) 5 (8.1) Aneurysm 2 (3.4) 4 (6.5) Bleeding 4 (6.8) 1 (1.6) Total 1 (17)t 2 (43)t *Numbers in parenthesis are percentages. tp <.4. and vein but remains superficial to them. It joins the brachial vein at the axillary level and forms the axillary vein. We have used the method initially described by Dagher et al. 7 in 1976 and later by LoGerfo et al.n in 1978 to construct the brachial artery-basilic vein fistula. The basilic vein is approached at the antecubital level just anterior to the medial epicondyle of the humerus. The distal end of the conduit vein may consist of either the basilic vein or a section of the median cubital vein. The medial brachial cutaneous nerve is in close proximity to the basilic vein and needs to be carefully separated from the vein during dissection (Fig. 1). The branches of the vein are suture ligated. The anterior surface of the vein is marked to avoid axial rotation during passage through the subcutaneous tunnel. A tunnel is then created anterior to the anterior wound edge (Fig. 2), and the vein is brought through the ttmnel for anastomosis to the brachial artery at the antecubital level with a running 6- prolene stitch (Fig. 3). RESULTS There were a total of 16 fistulas performed in 811 patients (37 female, 44 male) (Table I). Fifty-six patients underwent only one access procedure, 21 patients had two separate fistulas created, and two patients required three separate upper extremity shunts during follow-up. Of the 16 fistulas, 59 were constructed as BAVF and 47 used PTFE from the brachial artery to one of the following: basilic vein (n = 22), axillary vein (n = 18), and cephalic vein (n = 7). To maintain patency, thrombosed PTFEF were salvaged by thrombectomy in 1 instances, and extension of the PTFE into the axillary vein in six cases, the internal jugular vein in four cases, and dhe cephalic vein in one instance. There were no cases among the BAVF group for which secondary procedures to maintain patency were successful. Secondary procedures were performed on four separate thrombosed BAVF. All four procedures consisted of thrombectomies and were unsuccessful. Therefore

3 898 Coburn and Carney December 1994 Fig. 1. Exposure of basilic vein is facilitated by generous medial incision in arm. Course of medial brachial cutaneous nerve runs in close proximity to basilic vein, and is carefully preserved during dissection. Branches of vein are demonstrated and require suture ligation. Fig. 2. After ligation of branches of basilic vein, vein is mobilized, distal end transected, and subcutaneous tunnel constructed. secondary patency did not differ from primary patency, so only primary patency rates are considered in BAVF. Comparing the two groups, the mean patient age was virtually identical (PTFEF 64.1 years old, BAVF = 65.7 years old) (Table II). There were more women in the PTFEF group than the BAVF group (68% vs 49%, p = NS). The presence of coronary artery disease and diabetes mellitus was seen in nearly 5% of each group, whereas a history of peripheral vascular disease was seen more commonly in the patients with BAVF (46% vs 27%, p = NS). Overall there were nine failures in the BAVF group and 27 failures in the PTFEF group. Accumulated 1-year primary patency for BAVF and PTFEF were 9% and 7%, respectively (p <.1); 2-year primary patency rates were 86% and 49%, respectively (p <.1) (Fig. 4). Secondary 1-year and 2-year patency rates for PTFEF were 87% and

4 Volume 2, Number 6 Coburn and Carney 899 Fig. 3. After vein is delivered through subcutaneous tunnel (indicated by dashed lines), anastomosis is constructed from basilic vein to brachial artery. 64%, respectively. This 1-year PTFEF secondary patency rate was not significantly different from the 1-year patency rate of BAVF, whereas the 2-year secondary patency rate of PTFEF was significantly less than the 2-year patency rate of BAVF (p <.2). A list of complications and their corresponding rates is depicted for each group in Table II. Seventeen percent of patients with BAVF had a complication compared with 43% of patients with PTFEF (p <.4). Of note, bleeding problems were the only complication that were more frequently witnessed in the BAVF group (6.8% vs 1.6%,p = NS). After construction of life-tables, patency rates between BAVF and PTFEF were compared on the basis of the sex of the patient (Figs. 5 and 6). The 2-year patency rate for women with BAVF was 79%, compared with the 2-year primary patency rate of 5% for women with PTFEF (p <.5). At 1 year the primary patency rates for BAVF and PTFEF were 86% and 75%, respectively (p = NS). The secondary patency rates at 1-year and 2-years for PTFEF were 94% and 75%, respectively (p = NS compared with the 1-year and 2-year patency rates of BAVF). The 1-year and 2-year patency rates for men with BAVF were both 93%, compared to the 1-year and 2-year primary patency rates of men with PTFEF of 6% (p <.1), and 48% (p <.1), respec- tively. The secondary 1-year (73%) and 2-year patency rates (47%) of PTFEF in men were also less than the corresponding patency rates in BAVF (p <.7 and p <.1, respectively). Complicatiorls were observed in 6 of 29 women with BAVF (21%), compared with 14 of 32 women with PTFEF (44%, p <.5). Thirteen percent of men with BAVF had a compfication, compared with 4% of men with PTFEF (p <.6). The effect of patient sex on patency and complication rates were then examined within the basilic vein group (Fig. 7). Although 1-year and 2-year patency rates were lower for women (86% and 79%) than men (93% and 93%), these differences did not reach statistical significance. Likewise, complication rates did not significantly differ between women (21%) and men (13%) with BAVF. DISCUSSION The basilic vein is relatively large and has been called the "hidden vein," because it is not visible by simple inspection or palpation. 9 Hence, it has often escaped the damage inflicted by repeated iatrogeific venopunctures and intravenous lines and represents a high quality conduit for hemodialysis access. 9ql In addition, use of the native basilic vein offers advantages over PTFE: (1) only one anastomosis is required and the distal venous anastomosis,

5 9 Coburn and Carney December 1994 ACCUMULATED PATENCY RATE (%) (OVERALL) ACCUMULATED PATENCY RATE (%) (FEMALE) BASILIC VEIN + PTFE-PRIMARY FTFE-SECONDARY! i i i i i i.i TIME (months) *p<.1 +p<.1 ++ complication rate (baslllc-17%, PTFE- 43%, p<.4) Fig. 4. Accumulated patency rates for BAVF and PTFEF. At 1 year, primary patency rates for BAVF and PTFEF were 9% and 7%, respectively (p <.1); 2-year patency rates were 86% and 49%, respectively (p <.1). Secondary patency rates at 1 year (87%) and 2 years (64%) for PTFEF were significantly less than corresponding BAVF patency rates only at 2 years (p <.2). Seventeen percent of BAVG developed complication, compared with 43% of PTFEF (p <.2). the most common site for stenosis in PTFEF, is avoided, (2) a high flow rate is generated through the large-caliber basilic vein, and (3) the development of local infection does not mandate removal of a native vein fistula. Despite the undamaged nature of the basilic vein and advantages of native vein over PTFE, the BAVF has received only limited attention. The few studies of the BAVF report favorable results, s~2 The most extensive experience, published by Dagher, s reported a 7% patency rate at 8 years. Logerfo et al., n published a cumulative 1-year patency rate of 85% for 23 such shunts, with two complications. An 8% 1-year cumulative patency rate in 3 such fistulas was reported by Svoboda and Balaji, 9 with three complications. Cumulative 1-year and 2-year patency rates for 59 BAVF in this study were 9% and 86%, respectively. Both these patency rates were statistically higher than the 1- and 2-year primary patency rates for 47 PTFEF (7% and 49%, respectively). Although revision of a thrombosed PTFEF resulted in a secondary patency rate at 1 year that was not significantly different from the 1-year patency rate of BAVF, this similarity between patency rates disappeared at 2 years. The patency rate at 2 years for BAVF (86%) "--"--El-- BASILIC VEIN * "~ - PTFE-PRIMARY ~,, ~ PTFE-SECONDARY i i 1 i i!! * p.5 + p=ns TIME (months) ++ complication rate (basllle-21%, PTFE-44%, p<.5) Fig. 5. Accumulated patency rates among women with BAVF and PTFEF. At one year, primary patencies for BAVF and PTFEF were 86% and 75%, respectively (p = NS); 2-year patency rates were 79% and 5%, respectively (p <.5). Secondary patency rates for women with PTFEF at 1 year (94%) and 2 years (75%) were not significantly less than corresponding BAVF patency rates. Twenty-one percent of BAVF developed complication, compared with 44% ofptfef (p <.5). was statistically superior to the secondary patency rate of PTFEF (63%). Hence, it appears that revision of a thrombosed PTFEF may extend patency for a short period of time, but it does not maintain flow for the long term. Because this study was retrospectively conducted, it is difficult in some instances to determine specifically the reasons why a particular type of fistula was constructed in favor of the other fistula type. However, there were three factors that appeared to impact on this selection process. First, most BAVF were created within the last 3 years of the study, whereas most of the PTFEF were constructed during the first 3 years of the study. Second, approximately 5% of basilic veins were found to be of inadequate caliber for access creation (less than 4 mm in diameter), and, hence, a PTFEF was constructed. This incidence of inadequate basilic vein for access creation is identical to that reported in the literature. 12 Last, although 9% of the fistulas were created by the senior author (W. I. C.), the remaining were constructed by other staff vascular surgeons who generally favored creation of PTFEF rather than BAVF. Both patient age and sex did not

6 Volume 2, Number 6 Coburn and Carney 91 ACCUMULATED PATENCY RATE (%) (male) 1 - ACCUMULATED PATENCY RATE(%) 1- "k O '--'~ BASILIC VEIN + PTFE-PRIMARY... ~"... PTFE-SECONDARY ~ BASILIC VEIN (FEMALE) ~ BASILIC VEIN (MALE) I i I I i i i I I i I I i I i I TIME (months) * p<o,1 + p<o.o1 ++ complication rata (baslnc-13%, PTFE-4%, p<.6) Fig. 6. Accumulated pateney rates among males with BAVF and PTFEF. At one year, primary patencies for BAVF and PTFEF were 93% and 6%, respectively (p <.1); 2-year patency rates were 93% and 48%, respectively (2 <.1). Secondary patency rates for PTFEF at 1 year (87%) and 2 years (47%) were significantly less than corresponding BAVF patency rates only at 2 years (p <.1). Thirteen percent of men with BAVF had complication, compared with 4% of men with PTFEF (p <.6). appear to play a significant role in the decision to construct BAVF versus PTFEF. The overall complication rate of BAVF was statistically lower than that of I'TFEF (17% vs 43%). One complication that did occur more frequently in BAVF was bleeding. All four cases of bleeding occurred after repeated access attempts at the dialysis unit and each required operative exploration. In two instances the bleeding site was controlled, and the fistula was salvaged, whereas in the other two cases adequate control could not be obtained and the fistulas were ligated. The tendency to bleed was usually found to be associated with venous stenosis and venous hypertension. Although dialysis personnel initially expressed some concern regarding difficult canulation of the BAVF, with experience the dialysis nurses became accustomed to the location of the fistulas, and with time the BAVF became as obvious to the dialysis personnel as the PTFEF. Nevertheless, bleeding occurred in less than 7% of BAVF. Generally a period of 4 weeks after operation was allowed for maturation of the BAVF. Two complications that have been mentioned as a possible deterent to BAVF are high output heart failure and arterial steal, both TIME (months) * p=ns + complication ratas (famale-28 %, male-13 %, p=ns) Fig. 7. Accumulated patency rates for men and women with basilic vein fistulas. At 1 year, patency rates for men and women were 93% and 9%, respectively (p = NS); 2-year patency rates were 93% and 83%, respectively (p = NS). Twenty-one percent of women had developmerit of complications compared with 13% of men (p = NS). presumably caused by the high flow rate of these fistulas, n,13 There was not a single case of high output heart failure, despite the fact that nearly 5% of patients had documented coronary artery disease, and only two cases of arterial steal, both of which resolved without further surgery. Of the 1 complications that developed in the BAVF group, six were salvaged (two arterial steals, two graft infections, and two bleeding fistulas). The remaining four BAVF required eventual ligation (two aneurysms and two bleeding fistulas). Thirteen of the 2 complications that developed in patients with PTFEF were unsalvageable, resulting in fistula ligation (1 infected grafts, two aneurysms, and one arterial steal). The remaining seven PTFEF that developed complications were salvaged (four arterial steals, two aneurysms, and one bleeding fistula). :So it appears that infectious complications in PTFEF accounted for a considerable number of failed PTFEF in this study (1 infected grafts among a total of 27 graft failures). Infected prosthetic grafts generally require excision. On the other hand, two infections in BAVF were salvaged by incision and drainage of a surrounding abscess with preservation of the graft. It is possible that women may prove anatomically problematic in creating BAVF because the basilic vein may be smaller than that in men. Unfortunately documentation of either vein size or fistula blood flow was unavailable in most patients in this

7 IOURNAL OF VASCULAR SURGERY 92 Coburn and Carney December 1994 retrospective study, so this possibility remains unproven and speculative. The fact that more women underwent PTFEF than BAVF may reflect this phenomenon and may have somewhat biased the results, but this difference did not reach statistical significance. Moreover, the primary rate patency at 2 years for women with BAVF significantly exceeded that of female patients with PTFEF. In addition, BAVF constructed in women did not demonstrate either poorer patency rates or a higher complication rate than BAVF created in men. All patency rates reported for males with BAVF were superior to corresponding rates for PTFEF. Therefore it appears that the results reported herein for BAVF are particularly favorable in the male patient. Nevertheless, because the ultimate success of an AVF is judged by its ability to provide prolonged uncomplicated access, BAVF were demonstrated to be superior fistula conduits compared with PTFEF, even in female patients. Further supporting the use of BAVF, complication rates in both women and men were statistically more frequent in PTFEF than BAVF. Because there was no statistical difference in mean age between the PTFEF and BAVF groups, comparison of patency and complication rates between PTFEF and BAVF based on patient age was not performed in this study. Last, 15 patients underwent multiple upper extremity access procedures, such that a PTFEF (or BAVF) was created in a recently thrombosed BAVF (or PTFEF), located either in the ipsilateral or contralateral arm. In nine of these cases, the current fistula was placed in the arm opposite to that harboring the thrombosed fistula. It is unlikely that the thrombosed fistula adversely affected the outcome of the current fistula, which was located in the contralateral arm. For the remaining six cases, the two fistulas were created in the same arm. In four instances, a PTFEF, now thrombosed, preceeded a BAVF, and in two cases a BAVF, now clotted, preceeded a PTFEF. If these six patients are excluded from the patency and complication rate comparisons, all similarities and differences between the two fistula types are retained (data not shown). Hence, it appeared that there did not exist a bias toward either the creation of BAVF in previously unoperated arms or the construction of PTFEF in previously explored arms. Confronted with failed or unconstructable radiocephalic fistulas, results from this retrospective study suggest that the BAVF offers a superior access procedure to PTFEF. In fact, patency rates for BAVF in this study concur favorably with the best reported results of radiocephalic fistulas, and exceed those of PTFEF described in the literature. 3,4,~4 A prospective randomized trial of BAVF and PTFEF is required to confirm these results and establish the BAVF as the secondary access procedure of choice. REFERENCES 1. Brescia MJ, Cimino JE, Appel K, Hurwick BF. Chronic haemodialysis using venipuncture and a surgically created arteriovenous shunt. N Engl 1 Med 1966;275: Mehta S. Statistical summary of clinical results of vascular access procedures for hemodialysis. In: Sommer BG, Henry ML, eds. Vascular access for hemodialysis. Philadelphia: WL Gore and Associates, and Precept Press, 1991: Khedakian GM, Roedersheimer LR, Arbaugh JJ, Newmark K], King LR. Comparison of autogenous fistula versus expanded polytetrafluoroethylene graft fistula for angioaccess in hemodialysis. Am J Surg 1986;152: Bennion RS, Wilson SE. Hemodialysis and vascular access. In: Moore W, ed. Vascular surgery: A comprehensive review. Philadelphia: WB Saunders, 1993: Schuman ES, Gross GF, Hayes JF, Standage BA. Long-term patency of polytetrafluoroethylene graft fistulas. Am J Surg 1988;155: Jenkins AM, Buist TA, Glver SP. Meditma-term follow-up of forty autogenous vein and forty polytetrafluoroethylene (Gore Tex) grafts for vascular access. Surgery 198;88: Dagher H, Gelber R, Ramos E, et al. The use of basilic vein and brachial artery as an A-V fistula for long term hemodialysis. J Surg Res 1976;2: Dagher FJ. The upper arm AV hemoaccess: long term follow-up. J Cardiovasc Surg 1986;27: Svoboda JL Balagi MR. Basilic vein transposition: the ideal secondary fistula. In: Sommer BG, Henry ML, eds. Vascular access for hemodialysis. Philadelphia: WL Gore and Associates and Precept Press, 1991: Hibberd AD. Brachiobasilic fistula with autogenous basilic vein: surgical technique and pilot study. Aust N Z J Surg 1991;61: LoGerfo FW, Menzoian JO, Kumaki DJ, Idelson BA. Transposed basilic vein-brachial arteriovenous fistula: a rehable secondary-access procedure. Arch Surg 1978;113: Rivers SP, Scher LA, Sheehan E, Lynn R, Veith FJ. Basihc vein transposition: an underused autologous alternative to prosthetic dialysis angioaccess. I VASC SURG 1993;18: Anderson CB, Codd JR, GraffRA, et al. Cardiac failure and upper extremity arreriovenous dialysis fistulas. Arch Intern Med 1976;136: Reilly DT, Wood RF, Bell PR. Prospective study of dialysis fistulas: problem patients and their treatments. Br J Surg 1982;69: Submitted May 31, 1994; accepted Aug. 29, 1994.

8 Volume 2, Number 6 Coburl,'t and Carney 93 DISCUSSION Dr. G. Richard Curl (Buffalo, N.Y.). Drs. Coburn and Carney have presented the largest reported series of dialysis access procedures with use of the transposed basllic vein. They reported an admirable primary patency rate of 9% at I year and 8% at 2 years, with a better patency rate in men than women. They have retrospectively compared these results with a concurrent series of PTFE dialysis access grafts and have shown significantly superior patency rates with the native vein fistulas, comparing the primary PTFE patency rate at i year and both 1% to 2% patency rates at 2 years. A comparison of the complications of infection, steal, aneurysm, and bleeding between the two groups also showed a marked overall superiority in the basilic vein group, with only bleeding complications being slightly higher in the native vein group. These results support the authors' contention that the transposed basilic vein graft is the preferred dialysis access procedure, second only to the radiocephalic fistula. However, because this is not a prospective randomized study, a direct comparison between these groups must be done with caution. Therefore my first questions to the authors concern potential differences between the two groups. Can you tell us why some patients received PTFE grafts and some basilic vein fistulas? Is this the results of two different groups of surgeons, or was PTFE used in some cases because veins were believed to be inadequate? Might this then bias the results against the PTFE procedures? Can you clarify the types of PTFE grafting that were done? Were these all upper arm grafts, or were some of these forearm loop grafts, which have a recognized inferior patency rate? Despite these concerns, I do not believe anyone is terribly surprised that vascular access procedures performed with native vein stay patent longer and are less likely to become infected than procedures performed with a prosthetic. There are, however, other considerations that may be relevant in determining the optimal dialysis access procedures. For example, can they be performed with minimal morbidity in these patients who are often at poor risk? Was the type of anesthetic and operative time comparable, or is basilic vein transposition suitable only for patients able to tolerate a longer procedure, perhaps requiring general anesthetic? One potential complication after this procedure is arm swelling. Although other authors have reported a low incidence of this complication, the current series does not address this. Can you tell us whether any patients experienced significant arm edema after basllic vein transposition in their series, and whether this necessitated ligation of any vein grafts or significantly delayed its use? Dr. Michael C. Coburn. There were differences between the groups. As I showed, there were more women in the PTFE group; although it didn't reach statistical significance, the numbers may not have been large enough to eventually yield a statistically significant difference between the two groups. He also asked how we selected to do a PTFEF versus a basilic vein fistula. This was a retrospective study, so in some instances the reason why a particular type of fistula, was chosen was difficult to determine. However, there arc. at least three factors that impacted on this selection process.. First, most basilic vein fistulas were created within the last years of the study, whereas most of the PTFEF were constructed in the first 3 years of the study, which adds some bias to the results. Second, approximately 5% of basilic veins were found to be of inadequate caliber for access creation, and hence.. a PTFE fistula was constructed. This incidence of inadequate basilic vein fistula is identical to that published by Dr. Veith and his coauthors. Third, although most of the fistulas of both types were. created by the senior author, some were constructed by' other vascular surgeons, who generally constructed PTFEF rather than basilic vein fistulas, and I must add that most of the cases were constructed by the senior author. The next question was the type of PTFE grafts that: were constructed with an upper arm or forearm graft. They' were all upper arm grafts. The third question pertained to the operative time and the anesthetic used. We mostly use local anesthetic to perform the basilic vein fistulas. The operation time was slightly longer for the basilic vein fistulas, average from 1.5 to 2.5 hours, whereas the: PTFEFs generally took 3 minutes to an hour less. You also asked about arm swelling. All patients had minimal arm swelling. In no case did the fistula require: sacrifice because of that arm swelling, but there were a few instances where we had to wait longer than 4 weeks before: the dialysis fistula was accessed. You also asked about the minimal size of the vein. Approximately 4 mm would be the minimal size that we would use. Most basllic veins measure 5 to 7 mm in diameter. As I mentioned, in 95% of instances, when the basilic vein was explored, it was found to be of adequate caliber, and that leads me to the final questions that he asked about preoperative venography and duplex scanning. We didn't use either method to identify these veins, probably because of the success rate in the literature, as well as our success rate at finding adequate basilic vein. Dr. Mario Diaz (Albany, N.Y.). Were you able to identify the reason for the failure between the Gore-tex* graft, PTFE grafts and AVF? Did you follow any protocol *Gore-tex is a trademark ofw. L. Gore & Associates, Elkton, Md.

9 94 Coburn and Carney December 1994 of surveillance of these grafts to be able to detect lesions that could be fixed before failure of these grafts? Dr. Coburn. Concerning your first question regarding the basilic vein fistulas, there were nine failures; five thrombosed. There were a few attempts at thrombectomy, but they basically did not work. Two patients had development of pseudoaneurysms, which eventually required ligation, and another two patients had development of repeated bleeding episodes after dialysis and these were eventually ligated as well. Most of the PTFE grafts that failed thrombosed, some of them could be salvaged for short periods of time with thrombectomy, but most of them that went on to develop a decent secondary patency were revised. For example, a bridge fistula from the brachial artery to the basilic vein was created, or thrombosed, and then reanastomosis to the axiflary vein was performed. The other question was a surveillance question. We don't have any protocol right now for surveillance, but we've discussed instituting one. Dr. Anton N. Sidawy (Washington, D.C.). In this day and age, where we see more patients with human immunodeficiency virus, this will be an all autogenous tissue technique, which is very good. When the transposed veins fail, they fail because of multiple areas of stenosis along the vein. Maybe a surveillance program in these patients will prevent thrombosis because once thrombosis occurs, the incidence of salvaging these veins is much less than that when a prosthetic graft is thrombosed. Perhaps in this particular group of arteriovenous hemoaccesses, surveillance may play a big role, because just patching areas of stenosis may allow these fistulas to go on for many years. Dr. Fritzbach. I think your results are outstanding and very encouraging for those of us who continue to be frustrated by bridge grafts. One reason we keep doing them is that we end up meeting the patient for the first time when dialysis access is a matter of some urgency rather than giving us an opportunity for long-range planning. IfI were to sell this procedure to our nephrologists, what would I tell them with respect to how soon we could use the graft, rather than transposed basilic vein AVF? How soon can we use that safely after we create it? Dr. Coburn. In general, we have been waiting approximately 4 weeks, although in a few cases we had to wait a week or two longer because of some edema. We found that if you access it earlier, you tend to have problems with bleeding. Dr. Fritzbach. My second question relates to the conservatism of dialysis nurses in accepting new procedures. How do they feel about this with respect to cannulation? Dr. Coburn. Initially they had some difficulty, and some of the bleeding problems that we had may reflect that. However, once they understood where the fistula was and once it was matured, they had better success at it. We have purposely created a very narrow loop rather than a wide loop so the fistula tunnel is close to the incision. This makes it easier for them to find the fistula, and it is more familiar ground as far as finding the fistula. Dr. Sidawy. You said that you have two fistulas that you had to ligate because of excessive bleeding. We found that fistulas that have excessive bleeding in multiple sticks will have proximal venous occlusion, either in the subclavian vein or in the axillary vein, which causes the pressure in the fistulas to be higher, and they bleed more. We found that if you could pick up that area of proximal occlusion and manage that either with dilation or with a bypass from the axillary vein to the internal jugular vein, then you could salvage those fistulas. Dr. Coburn. We did not study the patients, but that is a very good point. Dr. CliffLynd (York, Pa.). We have used the basilic vein fistula since Most of them that we have made have remained patent for pretty much as long as the patient needs dialysis. The nice thing about them is that they do not have a venous anastomosis. Anybody who performs vascular access surgery knows that the venous anastomosis is the real trouble spot, so probably the biggest advantage of the basilic vein fistula is not having the venous anastomosis to worry about. The bleeding complications that I've seen have come from the dialysis nurses sticking through both walls of the graft; they have to get used to the basilic vein graft being easier to compress and easier to go all the way through, but once they get used to that there's not much of a problem with it. With regard to preoperative screening, we use the duplex technique. We found that branches occur within 3 or 4 cm of the elbow, and many times there are enough branches that make the basilic vein too short to use properly. We like to have a long loop on the arm rather than keep it closer to the inside of the arm, because it's much easier for the patient to lie there undergoing dialysis and have their arm out to the side rather than having the needles on the inside of the arm. Dr. David Lolley (Pittsburgh, Pa.). Is there an increase incidence of wound complications such as slough or nonhealing on this rather large incision? Have you noticed any difference between distal venous obstruction from the Gore-tex graft versus the venous one? It is my pet theory that Gore-rex seems to induce distal venous obstruction for some unknown reason. Dr. Coburn. We found very few problems with wound healing and infection in these patients with basilic vein fistulas; even among the patients with diabetes, the incidence is much lower than the PTFE group. With regard to distal venous stenoses, that's very well documented. As far as the PTFE grafts go, we certainly saw that with the PTFE grafts. We did not study the basilic vein grafts with regard to where the exact cause of the thrombosis was, so I cannot answer that question.