Prosthetic Arteriovenous
Fistula for Vascular Access in
Hemodialysis Bernard S. Levowitz, MD, FACS, Brooklyn, New York Lucia Flores, MD, Brooklyn, New York Irving Dunn, MD, Brooklyn, New York Eli Frumkin, MD, Brooklyn, New York
A subcutaneous arteriovenous fistula in the distal forearm is cul’rently the preferred method for blood access in long-term hemodialysis. In patients whose forearm vessels are unsuitable, modifications of the technic originally proposed by Brescia et aI [I] consist primarily of variations in anatomic location and graft composition [2]. Fistulas in the upper and lower extremities constructed with straight, looped, or bridging segments of autologous saphenous vein provide the most desirable alternative conduits for access to the circulation. Allografts of artery and vein [3-51 and bovine carotid heterografts [6-8] may also serve as substitute channels for vascular access. Although short-term results with silicone mandrilgrown autogenous grafts [9] are encouraging, the long delay required before harvesting is a distinct disadvantage. Another approach to circulatory access in the absence of autogenous veins is the use of a nonbiologic conduit [JO]. Dacron@ velour graft (Vasculour D, United States Catheter and Instrument Corp, Glens Falls, New York) was selected because of the established stability of its prosthetic-blood interface characterized as a firmly bonded inner fibrin layer enmeshed by looped fibrils of the fabric [II]. This internal lining was considered best suited to withstand repetitive needle puncture without separation of the inner capsule, dissection, and subsequent thrombus formation. The present study was designed to investigate prosthetic blood access in the canine model and evaluate its clinical application in selected patients. From the Dapartmants of Surgery and Medicine (Renal Diwslon). Jewish Hospital and Medical Center of Brooklyn, and the State University of New York, Downstate Medical Center, Brooklyn, New York This work was sup ported in part by USPHS Grant SD-lFR-05502. Reprint requests should be addressed to Bernard S Levowitz, MD, Department of Surgery, Brookdale Hospital Medical Center, Linden Blvd at Brookdale Plaza, Brooklyn, New York 11212.
368
Material and Methods
Eighteen adult mongrel dogs weighing from 15 to 22 kg were anesthetized with sodium pentobarbital and placed on a volume respirator. Crimped seamless woven Dacron and crimped Dacron velour grafts, 6 mm in diameter, were preclotted and tunneled subcutaneously across the lower abdomen. The prostheses were anastomosed from the common femoral artery (end-to-side) to the opposite common femoral vein (end-to-side) using 5-O synthetic suture material. Commencing two weeks post implantation the grafts were punctured percutaneously with # 14 gauge hemodialysis needles under light anesthesia at one to two week intervals. Heparin, 1 mg/kg of body weight, was administered intravenously at the time of cannulation. The needles were withdrawn 3 hours later and local pressure applied for hemostasis. In nine instances animals were pump-circulated 3 hours from the cannulated fistula to the external jugular vein. The dogs were observed for complications including wound infection, hematoma formation, and thrombosis of the graft. Angiographic and histologic studies of the graft were obtained within 4 hours of puncture in selected long-term preparations. The animals were otherwise sacrificed at various intervals and the grafts inspected for patency and thrombus formation. Results
A total of 197 punctures were performed in fourteen Dacron velour and four woven Dacron implants over a period of one and a half years. Anastomotic suturing and percutaneous needle penetration of the Dacron velour were performed with greater facility than with woven Dacron. No differences were noted in the amount of bleeding from preclotted prostheses immediately after implantation. Infection did not develop in any graft preparation during the course of the study. Hematoma was the foremost complication among the punctured Dacron velour implants; it occurred five times, three times in one animal. Thrombosis of
The American Journal of Surgery
Prosthetic Arteriovenous
the graft was observed once two weeks after an accidental overdose of heparin had been neutralized with protamine sulphate. Thrombosis was the leading complication in fistulas of woven Dacron. All four prostheses were OCeluded at 80,85,187, and 214 days after surgical implantation after 6, 8, 13, and 21 punctures, respectively. A large hematoma developed in one instance. Arteriograms obtained two to eighteen months postoperatively in dogs with multiple punctures showed no evidence of mural thrombus, distortion, or compression of the graft. (Figure 1.) Recent punctures produced local fabric disruption with some extravasation of blood into the surrounding tissues. Depending upon age, healed sites were either undetectable or identified grossly by areas of brownish discoloration attributed to hemosiderin deposits. (Figure 2.) Microscopically, the luminal surface disruption at puncture sites healed with a smooth continuous compacted fibrin lining. No defects were seen in the outer fibrous capsules. Although tissue responses to both materials were similar, gross characteristics of the grafts differed considerably. Throughout the study velour prostheses remained soft and pliable. On the other hand, woven Dacron developed into a firm inflexible conduit enveloped in dense connective tissue that was progressively resistant to penetration by the dialysis needle [IO]. Clinical Cases
Between March 1972 and December 1974, nineteen crimped Dacron velour grafts (6 mm diameter) were implanted in fifteen patients for maintenance hemodialysis covering ninety-six dialysis months. The results are summarized in Table I. In ten patients the indication was unilateral or bilateral failure of standard Brescia arteriovenous fistulas. [I]. Due to lack of suitable vessels in the upper extremity, prostheses were used as the initial fistula in five patients. Associated conditions which adversely affected fistula patency including diabetes mellitus, sickle cell anemia, drug addiction, obesity, and advanced age were present in the majority of these patients. Early in the series three looped Dacron velour forearm fistulas from the brachial artery crossed the elbow and were anastomosed to the median basilic vein. Two of these thrombosed in the same patient at twenty-two and two months. Kinking with obstruction to flow was considered the cause of failure. Subsequently, straight subcutaneous bypasses were performed in the arm between the distal brachial
volume132. sefaiembwlS76
Fistula in Hemodialysis
Figure 1. Arteriogram fhree months postoperatively showing Dacron velour femoral artery to femoral vein fistula after eleven percutaneous punctures with a #14 gauge canada. Note absence of filling defects or distortion of fhe graft.
artery and the proximal median basilic vein. (Figure 3.) Operative procedures were carried out under axillary nerve or brachial plexus block supplemented by local infiltration anesthesia. For exposure of vessels high in the axilla and just proximal to the antecubital crease, transverse rather than longitudinal incisions were used. They provided maximum length of accessible prosthesis free of overlying scar. An anterolateral course of the graft in the arm assured comfortable exposure of the externally rotated, adducted upper extremity during the dialysis run. Conventional vascular operative technics were employed in the Dacron velour-to-vessel anastomoses, end-to-side, including preclotting, fine monofilament suture, and systemic perioperative antibiotics. Routinely, hemodialysis was commenced by the fourth postoperative day. Other than the two looped forearm fistulas previously described, no instance of graft thrombosis has occurred. Graft-related infections developed twice in the same patient at four and one month postop-
Levowitz et al
Figure 2. Dacron velour graft seven months ‘after implantation. Hemorrhagic extravasation into adherent surrounding tissues Is caused by recent cannulation. Areas of discoloration within smooth inner capsule mark healed puncturesttesof various ages.
eratively. She was an elderly female whose debilitated general condition and poor wound healing were considered predisposing factors. All four of these late postoperative failures required prosthetic replacement. In one patient an infected cannula tract at five months postoperatively resulted in cellulitis of the arm, septicemia, and ultimately a mycotic aneurysm. Removal of the bypass and replacement in the opposite arm was mandatory. A juvenile diabetic, one month after fistula construction, showed ipsilateral ischemia of the hand and progressive neuropathy. Eleven grafts are presently functioning two to nine months postoperatively. No patient has exhibited evidence of hyperdynamic cardiac failure. Comments
Porosity of a prosthetic arterial graft determines the degree of host fibroblastic ingrowth, which sustains the viability and adherence of the inner capsule. After puncture by a large gauge needle, firm attachments of the inner layer to the graft material must be assured to prevent dissection or thrombosis. Liotta et al [12] employed knitted nylon and Dacron velour with impervious Silastica backing for implantable blood pumps. They found a strong mechanical bond between the internal fibrin lining and these fabrics even in the absence of tissue ingrowth. The highly cohesive fibrin-graft interface formed by a velour lattice effectively prevented separation and fragmentation by turbulent pump flows. Both types of vascular grafts utilized in the experimental model tolerated repetitive percutaneous
370
puncture. However, the high patency rate achieved with knitted Dacron velour compared to woven Dacron was attributed to better anchoring of the inner capsule at puncture sites by virtue of larger interstices and fibrillar enmeshment [11]. In contrast, the less adherent attachment of the inner layer to low porosity woven Dacron implants resulted in separation, fragmentation, and ultimately thrombosis after multiple punctures. Needle penetration in the direction of blood flow appeared to reduce flap formation and inner capsule dissection. To minimize fabric disruption and spread rather than sever Dacron fibers during penetration, a solid pencil point obturator has been devised to replace the beveled obturator in commercially available cannulas [9]. Prosthetic grafts have generally been considered unsuitable for access fistulas in hemodialysis. After multiple punctures the risks of seeding and perpetuating a septic focus within the network of a fabric foreign body should be substantially greater than in nonviable biologic substitutes. Unavoidable contamination introduced with each percutaneous cannulation would be reflected in an appreciable incidence of this complication. Contrary to expectations, no instance of graft infection was observed in any experimental preparation. Aside from the two previously mentioned cases, infection of a prosthesis has not occurred in over 1,200 clinical dialyses. For routine percutaneous blood access, our overall experience thus far suggests no unusual predilection of the synthetic fistula for infection. Numerous options are presently available when standard subcutaneous arteriovenous fiitulas cannot
The American Journal
oi Surgery
Prosthetic
TABLE
I
Pabent
Age (yr) and Sex
Results of Dacron
Velour
17, M 48, F
4
22, F
5 6 7 8
59, 62, 66, 67,
Flstula Flstula Frstula Frstula
F M F F
Forearm Loop
lndicatron
2 3
69, M
(6 mm diameter)
failure failure failure failure
+
27, 36, 24, 28, 44, 52,
F F F F F F
52, F
* Brachial
Artery
(2)
+
5
(2) (2) (2) (2)
+ + + +
5 7 4 4
+
1
+ + f
6 8 2
f + + +
1 4 2 2
f +
(2) (2)
vessels vessels vessels vessels (1) (1)
Poor forearm
vessels
Basilic
Vein
for Mamtenance
Cause of Failure
Frstula in Hemodialysis
Hemodialysls
in I5 Patients
Associated Condrtrons
Thrombosis Thrombosis
Infected cannula
Infected graft Infected graft
Course Alive
Lupus, drug addict Drabetes
Expired Al rve
Suckle cell anemia, pregnancy
Alive
Debility, wound sepsrs
poor healrng,
Diabetes Suckle cell anemia Drug add ret Diabetes Suckle cell anemia Obese ty Obesity
Al rve Allve Expired Expired
Alive Alive Exprred Al rve Al rve Alive Al rve
Frstula
be performed or if suitable autogenous veins are lacking [2]. By choice and for a more appropriate match between graft and host vessel diameters, the arm rather than the lower extremity is preferred for a straight bypass. This selection is based on reports of decreased patency rates in looped fistulas [ 71 and the two occluded grafts noted in our series. At the expense of slight loss in dialysis efficiency, single needle dialysis has been adopted to replace the conventional double cannulation procedure [13]. The new system offers the substantial advantages of better patient tolerance, decrease in the rate of complications attending percutaneous puncture and minimal length of fistula required for blood access. Modified bovine carotid heterograft has gained limited acceptance as a fistula bypass but its place in the long-term management of access for hemodialysis remains to be established. Uncertainties regarding supply, expense, and eventual host response are deterrents to widespread usage [14]. To a lesser extent similar considerations apply to frozen preserved vein homograft [4] and silicone mandril-grown autografts. By virtue of availability, biologic compatibility, and established vascular utility, our preliminary results suggest that Dacron velour may provide a more desirable alternative for fistula access in hemodialysis.
Volume 132, Se@~~nber1976
Clurabon (mo) __--
+ +
+
Poor forearm Poor forearm Poor forearm Poor forearm Frstula failure Flstula failure
to Median
implanted
22 2 9 6 5 3
(2)
Replacement 9 10 11 12 13 14 15
Arm Straight
_____ Frstula failure Replacement Replacement Frstula farlure Frstula farlure Replacement Frstula failure
1
Grafts
Arteriovenous
Figure 3. Straight subcutaneous tunnel in arm for Dacron velour graft anastomosed to brachial artery distatly and median basilic vein proximally.
371
Levowitz et al
Summary
References
Vascular access through subcutaneous prosthetic arteriovenous fistulas was studied in eighteen dogs. Dacron velour and woven Dacron grafts (6 mm diameter) were constructed across the lower abdomen between the common femoral artery and the opposite common femoral vein. In heparinized animals 197 percutaneous punctures were made with a # 14 gauge hemodialysis cannula at weekly intervals. Over a period of one and a half years there was no instance of infection. One of the fourteen Dacron velour and all four woven Dacron fistulas thrombosed. These data suggested the feasibility of achieving repetitive blood access through Dacron velour vascular prostheses. Nineteen Dacron velour fistula bypasses between the brachial artery and median basilic vein were performed in fifteen selected patients for a total dialysis period of ninety-six months. Failed standard subcutaneous fistulas or absence of suitable vessels in the upper extremity were indications for the primary procedure. Of three looped forearm fist&s, two thrombosed at twenty-two and two months. Complications among sixteen straight bypasses in the arm included two graft infections and one cannula tract infection. There were no instances of thrombosis in this group. The advantages of single needle dialysis in these high risk patients have been emphasized. Eleven grafts are presently functioning two to nine months postoperatively. Our preliminary results suggest that a Dacron velour fistula merits consideration as an alternative for vascular access in maintenance hemodialysis.
1. Brescia MD, Cimino JE, Appel K, Nurwich BJ: Chronic hemodialysis using venipuncture and surgically created arteriovenous fistula N Engl J Med 275: 1089, 1966 2. Cohen HE, Solit RW: Arteriovenous fistulas for chronic hemodialysis. Surg C/in North Am 53: 673, 1973. 3. Abudalu J, Urea I, Zonder HB, Rosenfeld JB: Hemodialysis treatment by means of a cadaver arterial allograft. Arch Surg 105: 798, 1972 4 Adar R, Siegal A, Bogokowsky H, Mazes M: The use of arteriovenous autograft and allograft fistulas for chronic hemodialysis. Surg Gynecol Obstet 136: 941, 1973. 5 Zerbino VR, Tice DA: Successful use of preserved allograft vein for chronic hemodialysis. Nephron IO: 61, 1973. 6. Chinitz JL, Yokoyama T, Bower R, Schwartz C: Self-sealing prosthesis for arterio-venous fistula in man. Trans Am Sot Artif Int Organs 18. 452, 1972. 7 Haimov M, Burrows L, Baez A, Neff M, Slifkin R: Alternatives for vascular access for hemodialysis Experience with autogenous saphenous vein autografts and bovine heterogafts. Surgery 75: 447, 1974. 8 Zincke H, Hirsche BL, Amamoo DG, Woods JE, Anderson RC: The use of bovine carotid grafts for hemodialysis and hyperalimentation. Surg Gynecol Obstet 139: 350, 1974. 9. Beemer RK, Hayes JF: Hemodialysis using a mandril-grown shunt. Trans Am Sot Artif lnt Organs 19: 43, 1973 10. Flores L. Dunn I, Frumkin E. Forte R, Requena R, Ryan J, Knopf M, Kirschner J, Levowitz BS: Dacron arterio-venous shunts for vascular access in hemodialysis Trans Am Sot Artif Int Organs 19: 33, 1973 11 Lindenauer SM, Lavanway JM, Fry WJ: Development of a velour-vascular prosthesis Current Topics in Surgical Research, vol II. New York and London, Academic Press, 1970 12. Liotta D, Hall CW, Akers WW, Villanueva A, O’Neal RM, DeBakey ME: A pseudoendocardium for implantable blood pumps. Trans Am Sot Artif Int Organs 25. 75, 1972. 13. Kopp KF, Gutch CF, Kolff WJ: Single needle dialysis. Tfans Am Sot Artif Int Organs 25: 75, 1972. 14. Haimov M, Jacobson JH: Experience with modified bovine arterial heterograft in peripheral vascular reconstruction and vascular access for hemodialysis Ann Surg 180: 291, 1974
372
The Amdcan Journal
cf Surgery
Fistula for Vascular Access in
Hemodialysis Bernard S. Levowitz, MD, FACS, Brooklyn, New York Lucia Flores, MD, Brooklyn, New York Irving Dunn, MD, Brooklyn, New York Eli Frumkin, MD, Brooklyn, New York
A subcutaneous arteriovenous fistula in the distal forearm is cul’rently the preferred method for blood access in long-term hemodialysis. In patients whose forearm vessels are unsuitable, modifications of the technic originally proposed by Brescia et aI [I] consist primarily of variations in anatomic location and graft composition [2]. Fistulas in the upper and lower extremities constructed with straight, looped, or bridging segments of autologous saphenous vein provide the most desirable alternative conduits for access to the circulation. Allografts of artery and vein [3-51 and bovine carotid heterografts [6-8] may also serve as substitute channels for vascular access. Although short-term results with silicone mandrilgrown autogenous grafts [9] are encouraging, the long delay required before harvesting is a distinct disadvantage. Another approach to circulatory access in the absence of autogenous veins is the use of a nonbiologic conduit [JO]. Dacron@ velour graft (Vasculour D, United States Catheter and Instrument Corp, Glens Falls, New York) was selected because of the established stability of its prosthetic-blood interface characterized as a firmly bonded inner fibrin layer enmeshed by looped fibrils of the fabric [II]. This internal lining was considered best suited to withstand repetitive needle puncture without separation of the inner capsule, dissection, and subsequent thrombus formation. The present study was designed to investigate prosthetic blood access in the canine model and evaluate its clinical application in selected patients. From the Dapartmants of Surgery and Medicine (Renal Diwslon). Jewish Hospital and Medical Center of Brooklyn, and the State University of New York, Downstate Medical Center, Brooklyn, New York This work was sup ported in part by USPHS Grant SD-lFR-05502. Reprint requests should be addressed to Bernard S Levowitz, MD, Department of Surgery, Brookdale Hospital Medical Center, Linden Blvd at Brookdale Plaza, Brooklyn, New York 11212.
368
Material and Methods
Eighteen adult mongrel dogs weighing from 15 to 22 kg were anesthetized with sodium pentobarbital and placed on a volume respirator. Crimped seamless woven Dacron and crimped Dacron velour grafts, 6 mm in diameter, were preclotted and tunneled subcutaneously across the lower abdomen. The prostheses were anastomosed from the common femoral artery (end-to-side) to the opposite common femoral vein (end-to-side) using 5-O synthetic suture material. Commencing two weeks post implantation the grafts were punctured percutaneously with # 14 gauge hemodialysis needles under light anesthesia at one to two week intervals. Heparin, 1 mg/kg of body weight, was administered intravenously at the time of cannulation. The needles were withdrawn 3 hours later and local pressure applied for hemostasis. In nine instances animals were pump-circulated 3 hours from the cannulated fistula to the external jugular vein. The dogs were observed for complications including wound infection, hematoma formation, and thrombosis of the graft. Angiographic and histologic studies of the graft were obtained within 4 hours of puncture in selected long-term preparations. The animals were otherwise sacrificed at various intervals and the grafts inspected for patency and thrombus formation. Results
A total of 197 punctures were performed in fourteen Dacron velour and four woven Dacron implants over a period of one and a half years. Anastomotic suturing and percutaneous needle penetration of the Dacron velour were performed with greater facility than with woven Dacron. No differences were noted in the amount of bleeding from preclotted prostheses immediately after implantation. Infection did not develop in any graft preparation during the course of the study. Hematoma was the foremost complication among the punctured Dacron velour implants; it occurred five times, three times in one animal. Thrombosis of
The American Journal of Surgery
Prosthetic Arteriovenous
the graft was observed once two weeks after an accidental overdose of heparin had been neutralized with protamine sulphate. Thrombosis was the leading complication in fistulas of woven Dacron. All four prostheses were OCeluded at 80,85,187, and 214 days after surgical implantation after 6, 8, 13, and 21 punctures, respectively. A large hematoma developed in one instance. Arteriograms obtained two to eighteen months postoperatively in dogs with multiple punctures showed no evidence of mural thrombus, distortion, or compression of the graft. (Figure 1.) Recent punctures produced local fabric disruption with some extravasation of blood into the surrounding tissues. Depending upon age, healed sites were either undetectable or identified grossly by areas of brownish discoloration attributed to hemosiderin deposits. (Figure 2.) Microscopically, the luminal surface disruption at puncture sites healed with a smooth continuous compacted fibrin lining. No defects were seen in the outer fibrous capsules. Although tissue responses to both materials were similar, gross characteristics of the grafts differed considerably. Throughout the study velour prostheses remained soft and pliable. On the other hand, woven Dacron developed into a firm inflexible conduit enveloped in dense connective tissue that was progressively resistant to penetration by the dialysis needle [IO]. Clinical Cases
Between March 1972 and December 1974, nineteen crimped Dacron velour grafts (6 mm diameter) were implanted in fifteen patients for maintenance hemodialysis covering ninety-six dialysis months. The results are summarized in Table I. In ten patients the indication was unilateral or bilateral failure of standard Brescia arteriovenous fistulas. [I]. Due to lack of suitable vessels in the upper extremity, prostheses were used as the initial fistula in five patients. Associated conditions which adversely affected fistula patency including diabetes mellitus, sickle cell anemia, drug addiction, obesity, and advanced age were present in the majority of these patients. Early in the series three looped Dacron velour forearm fistulas from the brachial artery crossed the elbow and were anastomosed to the median basilic vein. Two of these thrombosed in the same patient at twenty-two and two months. Kinking with obstruction to flow was considered the cause of failure. Subsequently, straight subcutaneous bypasses were performed in the arm between the distal brachial
volume132. sefaiembwlS76
Fistula in Hemodialysis
Figure 1. Arteriogram fhree months postoperatively showing Dacron velour femoral artery to femoral vein fistula after eleven percutaneous punctures with a #14 gauge canada. Note absence of filling defects or distortion of fhe graft.
artery and the proximal median basilic vein. (Figure 3.) Operative procedures were carried out under axillary nerve or brachial plexus block supplemented by local infiltration anesthesia. For exposure of vessels high in the axilla and just proximal to the antecubital crease, transverse rather than longitudinal incisions were used. They provided maximum length of accessible prosthesis free of overlying scar. An anterolateral course of the graft in the arm assured comfortable exposure of the externally rotated, adducted upper extremity during the dialysis run. Conventional vascular operative technics were employed in the Dacron velour-to-vessel anastomoses, end-to-side, including preclotting, fine monofilament suture, and systemic perioperative antibiotics. Routinely, hemodialysis was commenced by the fourth postoperative day. Other than the two looped forearm fistulas previously described, no instance of graft thrombosis has occurred. Graft-related infections developed twice in the same patient at four and one month postop-
Levowitz et al
Figure 2. Dacron velour graft seven months ‘after implantation. Hemorrhagic extravasation into adherent surrounding tissues Is caused by recent cannulation. Areas of discoloration within smooth inner capsule mark healed puncturesttesof various ages.
eratively. She was an elderly female whose debilitated general condition and poor wound healing were considered predisposing factors. All four of these late postoperative failures required prosthetic replacement. In one patient an infected cannula tract at five months postoperatively resulted in cellulitis of the arm, septicemia, and ultimately a mycotic aneurysm. Removal of the bypass and replacement in the opposite arm was mandatory. A juvenile diabetic, one month after fistula construction, showed ipsilateral ischemia of the hand and progressive neuropathy. Eleven grafts are presently functioning two to nine months postoperatively. No patient has exhibited evidence of hyperdynamic cardiac failure. Comments
Porosity of a prosthetic arterial graft determines the degree of host fibroblastic ingrowth, which sustains the viability and adherence of the inner capsule. After puncture by a large gauge needle, firm attachments of the inner layer to the graft material must be assured to prevent dissection or thrombosis. Liotta et al [12] employed knitted nylon and Dacron velour with impervious Silastica backing for implantable blood pumps. They found a strong mechanical bond between the internal fibrin lining and these fabrics even in the absence of tissue ingrowth. The highly cohesive fibrin-graft interface formed by a velour lattice effectively prevented separation and fragmentation by turbulent pump flows. Both types of vascular grafts utilized in the experimental model tolerated repetitive percutaneous
370
puncture. However, the high patency rate achieved with knitted Dacron velour compared to woven Dacron was attributed to better anchoring of the inner capsule at puncture sites by virtue of larger interstices and fibrillar enmeshment [11]. In contrast, the less adherent attachment of the inner layer to low porosity woven Dacron implants resulted in separation, fragmentation, and ultimately thrombosis after multiple punctures. Needle penetration in the direction of blood flow appeared to reduce flap formation and inner capsule dissection. To minimize fabric disruption and spread rather than sever Dacron fibers during penetration, a solid pencil point obturator has been devised to replace the beveled obturator in commercially available cannulas [9]. Prosthetic grafts have generally been considered unsuitable for access fistulas in hemodialysis. After multiple punctures the risks of seeding and perpetuating a septic focus within the network of a fabric foreign body should be substantially greater than in nonviable biologic substitutes. Unavoidable contamination introduced with each percutaneous cannulation would be reflected in an appreciable incidence of this complication. Contrary to expectations, no instance of graft infection was observed in any experimental preparation. Aside from the two previously mentioned cases, infection of a prosthesis has not occurred in over 1,200 clinical dialyses. For routine percutaneous blood access, our overall experience thus far suggests no unusual predilection of the synthetic fistula for infection. Numerous options are presently available when standard subcutaneous arteriovenous fiitulas cannot
The American Journal
oi Surgery
Prosthetic
TABLE
I
Pabent
Age (yr) and Sex
Results of Dacron
Velour
17, M 48, F
4
22, F
5 6 7 8
59, 62, 66, 67,
Flstula Flstula Frstula Frstula
F M F F
Forearm Loop
lndicatron
2 3
69, M
(6 mm diameter)
failure failure failure failure
+
27, 36, 24, 28, 44, 52,
F F F F F F
52, F
* Brachial
Artery
(2)
+
5
(2) (2) (2) (2)
+ + + +
5 7 4 4
+
1
+ + f
6 8 2
f + + +
1 4 2 2
f +
(2) (2)
vessels vessels vessels vessels (1) (1)
Poor forearm
vessels
Basilic
Vein
for Mamtenance
Cause of Failure
Frstula in Hemodialysis
Hemodialysls
in I5 Patients
Associated Condrtrons
Thrombosis Thrombosis
Infected cannula
Infected graft Infected graft
Course Alive
Lupus, drug addict Drabetes
Expired Al rve
Suckle cell anemia, pregnancy
Alive
Debility, wound sepsrs
poor healrng,
Diabetes Suckle cell anemia Drug add ret Diabetes Suckle cell anemia Obese ty Obesity
Al rve Allve Expired Expired
Alive Alive Exprred Al rve Al rve Alive Al rve
Frstula
be performed or if suitable autogenous veins are lacking [2]. By choice and for a more appropriate match between graft and host vessel diameters, the arm rather than the lower extremity is preferred for a straight bypass. This selection is based on reports of decreased patency rates in looped fistulas [ 71 and the two occluded grafts noted in our series. At the expense of slight loss in dialysis efficiency, single needle dialysis has been adopted to replace the conventional double cannulation procedure [13]. The new system offers the substantial advantages of better patient tolerance, decrease in the rate of complications attending percutaneous puncture and minimal length of fistula required for blood access. Modified bovine carotid heterograft has gained limited acceptance as a fistula bypass but its place in the long-term management of access for hemodialysis remains to be established. Uncertainties regarding supply, expense, and eventual host response are deterrents to widespread usage [14]. To a lesser extent similar considerations apply to frozen preserved vein homograft [4] and silicone mandril-grown autografts. By virtue of availability, biologic compatibility, and established vascular utility, our preliminary results suggest that Dacron velour may provide a more desirable alternative for fistula access in hemodialysis.
Volume 132, Se@~~nber1976
Clurabon (mo) __--
+ +
+
Poor forearm Poor forearm Poor forearm Poor forearm Frstula failure Flstula failure
to Median
implanted
22 2 9 6 5 3
(2)
Replacement 9 10 11 12 13 14 15
Arm Straight
_____ Frstula failure Replacement Replacement Frstula farlure Frstula farlure Replacement Frstula failure
1
Grafts
Arteriovenous
Figure 3. Straight subcutaneous tunnel in arm for Dacron velour graft anastomosed to brachial artery distatly and median basilic vein proximally.
371
Levowitz et al
Summary
References
Vascular access through subcutaneous prosthetic arteriovenous fistulas was studied in eighteen dogs. Dacron velour and woven Dacron grafts (6 mm diameter) were constructed across the lower abdomen between the common femoral artery and the opposite common femoral vein. In heparinized animals 197 percutaneous punctures were made with a # 14 gauge hemodialysis cannula at weekly intervals. Over a period of one and a half years there was no instance of infection. One of the fourteen Dacron velour and all four woven Dacron fistulas thrombosed. These data suggested the feasibility of achieving repetitive blood access through Dacron velour vascular prostheses. Nineteen Dacron velour fistula bypasses between the brachial artery and median basilic vein were performed in fifteen selected patients for a total dialysis period of ninety-six months. Failed standard subcutaneous fistulas or absence of suitable vessels in the upper extremity were indications for the primary procedure. Of three looped forearm fist&s, two thrombosed at twenty-two and two months. Complications among sixteen straight bypasses in the arm included two graft infections and one cannula tract infection. There were no instances of thrombosis in this group. The advantages of single needle dialysis in these high risk patients have been emphasized. Eleven grafts are presently functioning two to nine months postoperatively. Our preliminary results suggest that a Dacron velour fistula merits consideration as an alternative for vascular access in maintenance hemodialysis.
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