Arterio-Venous Access Utilizing Modified Bovine Arterial Grafts for Hemodialysis A. HASSAN MOHAIDEEN, M.D., JAIRO MENDIVIL, M.D., MORRELL M. AVRAM, M.D., ROBERT A. MAINZER, M.D.

Forty-seven patients with chronic renal failure presenting with a loss of vascular access precluding hemodialysis were subjected to 105 surgical procedures to establish and to maintain an arteriovenous fistulae. 67 bovine heterografts were implanted over a 30 month period and observed for 6 or more months. Fifteen, or 32% of the patients, died during the study period. Eleven patients died with a functional fistula. Twenty fistulae continued to function at the end of 36 months constituting a 46.3% graft survival rate. Hemodialysis was continued in 11 of 12 patients via a P.T.F.E. Goretex graft or via a matured Brescia Fistula. The remaining patient experienced graft failure at the end of the study period. Graft thrombosis was observed in 31 of 67 grafts placed (46%). Successful thrombectomy was achieved in 52%. Fourteen grafts developed frank aneurysms with overt rupture in 8. All patients with aneurysms were negro. Six of 8 patients with aneurysm presented with severe hypertension. Thirteen aneurysms were resected without loss of life or limb. The use of bovine grafts in hypertensive negro patients is believed to be contraindicated.

T HE SUCCESSFUL DEVELOPMENT and subsequent ex-

perimental utilization of modified collagen arterial grafts of bovine origin, exhibiting minimal antigenesity, was first reported in 1956.9 The first clinical application of the modified collagen heterograft as a successful femoro-popliteal bypass conduit was reported by Rosenberg in 1962.10 Subsequent reports of successful long term clinical observations of this modified collagen graft in human subjects has suggested its use in selected chronic renal failure patients in whom there is a loss of arterial or venous access precluding continued hemodialysis. A total of 67 modified bovine grafts were implanted into a group of 47 chronic renal failure patients each of whom had sustained a loss of vascular access precluding hemodialysis. The patient population included five caucasian males and 13 caucasian females averaging 60.7 years in age and 10 negro males and 19 negro females averaging 47.5 years in age. The series of 67 bovine graft implantations included all patients operated upon during the period from July 1, 1973 to DeSubmitted for publication: October 6, 1976. Reprint requests: Department of Surgery, Long Island College Hospital, 340 Henry Street, Brooklyn, N.Y. 11201.

643

From the Departments of Surgery of the Long Island College Hospital and the State University of New York, Down State Medical Center, Brooklyn, New York

cember 31, 1975 and followed through to June 30, 1976. Eight patients admitted to the series required primary bovine grafts by reason of absence of any potential arterio-venous access route. Thirty-four patients each received a single bovine graft whereas 13 patients required a combined total of 33 grafts. Five patients were diabetic and 19 exhibited hypertension. The loss of vascular access in chronic renal failure patients undergoing hemodialysis is most frequently due to a venous outflow tract deficit. While the use of two widely separated arterial sites for afferent and efferent limbs of the conventional hemodialysis circuit or the use of the single needle modification are feasible, repeated arterial or venous punctures soon result in aneurysm formation or thrombosis. The optimum site of selection for placement of an arteriovenous fistula with interposition of a bovine graft is determined by the availability of a satisfactory venous outflow channel. In the current series the outflow tract included the basilic vein in 44 instances, the antecubital vein in three, the femoral vein in 10, the saphenous system in 8, the external iliac vein and the distal superficial femoral artery in the remaining two instances. The subcutaneous disposition of the bovine graft was in part determined by the availability of a satisfactory arterial inflow tract as this related anatomically to the venous outflow tract. Accordingly, 47 grafts were placed subcutaneously in an upper extremity. Of these grafts 44 were created with a U loop configuration and three as straight conduits. The upper extremity was favored as the graft site of choice because of the technical ease of the surgical approach and the facility with which hemodialysis could be conducted. The lower extremities were utilized primarily in those patients exhibiting a loss of venous access in the upper extremity. Of the 20 grafts placed subcutaneously in

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644

the thigh, 16 were straight conduits and four had a J loop configuration. The brachial or brachio-radial artery was utilized in 36 instances, the proximal radial artery in 8, the distal radial artery in three and the superficial femoral artery in 20. Arteries less than 3mm in size were avoided because of a high incidence of graft failure. The placement of the bovine graft in the upper extremity was performed under local procaine infiltration anesthesia on 35 occasions and under general anesthesia on 12 occasions whereas all 20 lower extremity implantations required general anesthesia. Local anesthesia was supplemented with intravenous Fentanyl or Demerol. All patients were vigorously dialyzed before undergoing surgery. Hemic levels were enhanced by preoperative transfusions to obtain hematocrit levels between 25% and 30%o. Intra-operative transfusions of blood and plasma were utilized as indicated to maintain the patient's usual blood pressure. Technical Considerations

Standard anatomic surgical approaches to the various vessels constituting the afferent and efferent limbs of the proposed arterio-venous fistulae were made. The modified bovine arterial grafts were irrigated with one liter of normal saline followed by a second liter of saline containing 5000 units of heparin. The selection of various sizes of bovine grafts for implantation were determined by availability rather than by design. Most grafts utilized in this series measured 28 to 32 cm in length and 7 mm in diameter. After preparation of the graft was accomplished, a marking suture was threaded through the adventia along one radiant of the graft and throughout its entire length to assure proper orientation of its axial disposition in a manner described by Linton.6 Placement of the graft was facilitated by the use of a tunnelling tool creating a subdermal tunnel. An apical counter-incision was required when a U loop or J loop graft disposition was desired. The graft was drawn through the tunnelling device by a previously placed traction suture. Grafts presenting a loop disposition were checked for axial rotation by determining the location of the axial adventitial marking suture and by distention of the graft with saline. It is suggested that this maneuver be repeated after implantation of the graft into the efferent venous limb has been effected. Care is required when placing grafts over areas subject to the stresses of flexion such as the elbow. This is readily achieved by placing the tunnel on the medial aspect of the elbow but anterior to the medial epicondyle.

Ann. Surg. c November 1977

The efferent venous anastomosis was constructed initially utilizing systemic heparinization. The graft was trimmed to obviate angulation and the anastomosis created with two number six zero dacron arterial sutures. Upon completion of the anastomosis the graft was again checked for axial rotation and the integrity of the suture line tested by instillation of saline via the open proximal limb of the graft. Upon corroboration of the graft's axial orientation and the integrity of the anastomosis, the proximal venous occluding serafin was removed and more saline instilled to assess the effectiveness of the efferent venous run off tract. All foregoing three factors being judged satisfactory the distal end of the graft just proximal to the anastomosis was occluded with a gentle serafin to permit unrestricted venous flow to pass by the anastomosis. The arterial anastomosis was performed as previously described after first shaping the proximal end of the graft to assure proper hemodynamic accommodation between the host artery and the bovine graft. Upon completion of the arterial anastomosis the integrity of the anastomosis was tested by applying a soft serafin to the graftjust distal to the arterial anastomosis and removing the distally placed occluding arterial clamp. Upon observing a satisfactory anastomotic integrity, both previously placed distal and proximal graft serafins were removed and, lastly, the proximal occluding arterial clamp was released. The appearance of an immediate arterial expansile pulse in both the graft and the venous outflow tract and the presence of a perceptible thrill within both arterial and venous anastomoses was evidence of a satisfactorily functioning arterio-venous fistula. Before effecting wound closure the graft should be inspected for evidence of pressure compression and the condition corrected if present. This generally requires minor alterations of the subcutaneous bed to release tension and is especially applicable to grafts with a loop disposition.

Post Operative Considerations

Patients undergoing the creation of arterio-venous fistulae with interposition of bovine grafts require observation to determine the continued patency of the graft and inspection of the operative area for evidence of hemorrhage. Post-operatively systemic heparinization was discontinued and antibiotics were used for 7 days. The agent most frequently prescribed was Doxocycline (Vibramycin) as a preoperative 200 mg intravenous loading dose followed by 100 mg orally daily for 7 days. Edema of varying degree was observed in the operative site post-operatively. This was generally self-

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limited and was mitigated by elevation of the part. The use of elastic compression dressings is to be avoided. There appears to be some relationship to the degree of edema and the thoroughness with which the graft is irrigated prior to implantation, the edema being inversely proportional to the effectiveness of the preparative process. Hemodialysis via the freshly implanted graft is interdicted for some three weeks post-operatively to facilitate resolution of edema and the development of graft adherence to the host's subcutaneous tissues. Early hemodialysis was associated with an increased incidence of graft thrombosis and was generally induced by excessive pressures required to control bleeding following removal of dialysis needles. Complications

Thrombosis Early thrombosis of bovine grafts was observed within 30 days of implantation in 14 of 67 grafts (21%). The cause of early graft thrombosis was deemed technical in 6 instances and occurred on the second, third, seventh, fourteenth and twentieth days postoperatively. The technical errors included such factors as selection of an inadequate or compromised venous outflow tract, technically imperfect vascular anastomoses, improper graft placement causing angulation, axial rotation or excessive tissue tension upon the graft and unexpected hypotensive episodes occurring both intra-operatively and postoperatively. These hypotensive episodes were generally related to inadequate pre-operative hydration and insufficient intra-operative and post-operative blood and fluid replacement. Two instances of thrombosis were deemed related to premature utilization of the graft for hemodialysis and resulted from application of excessive compression of the graft to control bleeding following the removal of dialysis needles. Ten grafts exhibiting early thrombosis were located in an upper extremity and the remaining five were located in a lower extremity. Thrombectomy was attempted on 11 occassions with successful revascularization in five (45%). The Fogarty catheter proved most effective permitting extraction of the thrombus from within the graft and the outflow tract in addition to providing information concerning the dimensions of the vascular anastomosis. It is suggested that the operative approach be made through the distal end of the graft and that venotomy and arteriotomy be avoided to obviate possible compromise in the diameter of both the inflow and outflow tracts expecially in vessels of marginal size. Successful

645

restoration of blood flow was achieved as late as 96 hours after thrombosis; however, early thrombectomy within the first 48 hours was associated with a greater salvage rate. Four acute thromboses were not explored because of coincidental heart failure and prolonged hypotension. One patient refused thrombectomy. Delayed or late thrombosis occurring later than 30 days after implantation of the graft was observed on 17 occassions affecting 10 patients. Thrombosis occurred between the fortieth post operative day and the eleventh post operative month. Thrombectomy was attempted in 14 instances with effective revascularization permitting continued hemodialysis in eight grafts (57%). The factors leading to thrombosis included technical difficulties with application of excessive pressure to the graft following the removal of dialysis needles. The probability of recurrent episodes of hypotension as the cause of thrombosis was suggested by the demonstration of multi-layered tubular clots extracted on two occassions. These hypotensive episodes were presumed to be related to the dehydrating affects of hemodialysis. In addition to the foregoing etiological factors 6 known instances of progressive stenosis of the graft outflow tract were observed. These stenoses presented a dense fibrous sclerosis which, in one instance, involved the distal 6 cm of the graft reducing the lumen to a thread like aperature terminating at the anastomotic site. A second patient experienced recurrent episodes of thrombosis in two successively placed grafts. In each instance the fibrosis extended from the efferent venous anastomotic site into the venous channel for some 4 cm. The remaining three patients exhibited a fibrous cicatrix involving the distal one to 2 cm of the graft and extending some one to 2 cm into the venous runoff channel as well. Four of these grafts were abandoned and two were salvaged by section of the distal normal appearing graft with reimplantation into a new venous runoff tract in one case and by the addition of a new length of graft to the freshly sectioned but matured graft and implanting the new segment into the same venous runoff tract just proximal to the stenotic segment but into grossly uninvolved vein. The remaining two instances of delayed thrombosis were secondary to infection stemming from contamination introduced incidental to the performance of hemodialysis. Thirteen of the 17 delayed episodes of thrombosis were located in an upper extremity and the four remaining were situated in a thigh. The data relating to graft thrombosis are summarized in Table 1. Of interest, but of no probable significance, is the incidence of thrombosis experienced in caucasian patients as opposed to negro patients, an incidence of 68% as compared to 41% respectively.

646

MOHAIDEEN AND OTHERS

Ann. Surg.

November 1977

TABLE 1. Bovine Graft Thrombosis Observed Within the First Thirty Days of Implantation (Early) and After Thirty Days of Implantation (Late) Incidence of Great Thrombosis

Number of patients % of patients by race Number of grafts % of grafts by race Number of thrombectomies

Combined Thrombosis

Late Thrombosis

Early Thrombosis

Total Patients by Race Negro

Caucasian

Total

Negro

Caucasian

Total

Negro

Caucasian

Total

Negro

Caucasian

29 62% 42 63%

18 38% 25 37%

47

6 21% 6 14% 6 3

8 44% 8 32% 5 2 40%

14

6 21% 8

10

6 4

4 22% 9 36% 8 4

12 68% 17 68% 13 6

66%

50%o

12 41% 14 33% 12 7 58%

67

Successful thrombectomies Success rate

50%

14

19%C 11 5 45%

17 , * 14 8 57%

Total 24 31 25 13 52%

46%c

Incidence of Graft Thrombosis by Site of Implantation- Upper or Lower Extremity

Distribution of Grafts Early Thrombosis

by Site

Number of grafts implanted % Distribution of grafts Number of grafts undergoing thrombosis % of grafts undergoing thrombosis Distribution of thrombosed grafts by site

Upper

Lower

Total

47 70%

20 309c

67

Upper

Lower

10 21% 71%

20%

4

29%o

Combined Thrombosis

Late Thrombosis Total

14

Upper

Lower

Total

Upper

Lower

13 28% 76%

4

17

20%

23 49% 74%

40%o 26%

25%c

8

Total

31

The incidence of graft thrombosis occurring in Negro and Caucasian patients is compared. The effect of the site of graft implantation upon the incidence of graft thrombosis is outlined.

Infection Infection of the graft as an immediate complication of graft placement was not experienced. The application of a double skin preparation, the avoidance of hematomata intra-operatively and the use of prophylactic antibiotics are believed factors limiting the incidence of infection. Frank late clinical infection was observed in two patients. The first was a 46 year old female who developed a hematoma about the graft after 6 weeks of dialysis and who had active uncontrolled pelvic inflammatory disease. The infection is believed to have metastasized to the hematoma. The second patient was a 55 year old female who entered the dialysis unit with a previously placed bovine graft which had become infected. The infected graft was excised and a new graft placed in the contra-lateral forearm some three weeks after the primary excision. The new graft functioned satisfactorily as a dialysis access route for 6 months and then became infected at the sites of needle puncture. The graft thrombosed spontaneously and was subsequently excised. The two instances of graft thrombosis secondary to infection have already been alluded to and are recorded once again in this section on infections. These two patients represent occult infections in that no evidence of infection was observed prior to attempted thrombectomy. Unfortunately, no data pertaining to the status of the venous outflow tract at the time of removal of the graft was recorded. Presumably, the outflow tract was obstructed since no systemic manifesta-

tion of sepsis was evident. These grafts had been used for hemodialysis for three and five months respectively. Aneurysm Formation

True aneurysm formation as opposed to an iatrogenicly induced false aneurysm was observed in 14 instances in 8 patients. Ten of the grafts developed multiple aneurysmal dilitations. The remaining exhibited a solitary area of dilitation. One graft was observed to become aneurysmal within 30 days of implantation and required excision within 60 days of implantation without having been used for hemodialysis. Seven grafts were located in a forearm and seven in a thigh. Six of the 8 patients exhibited severe hypertension with systolic pressures ranging above 180 mm Hg. All patients exhibiting aneurysmal degeneration of their grafts were negro. Of moment, is the observation that 40%o of the patients reported in this series exhibited hypertension and that the incidence of hypertension was 45% for negros and 33% for caucasian patients. Among negro patients 34% exhibited severe hypertension (i.e. in excess of 180 mm Hg) as opposed to only 17% of caucasian patients. (Table 2) The time lag between the observation of aneurysmal formation and rupture of the aneurysm was of short duration and generally was related to the hemodialysis conducted immediately before the appearance of a massive hematoma. Eight aneurysms presenting massive hemorrhage and skin necrosis were controlled in seven instances by

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simple ligation of the proximal and distal ends of the graft. The eighth graft was unrecognizable to the point of arterial implantation in the brachial artery and required a venous patch to maintain arterial continuity. One of the patients treated by simple ligation rebled from the arterial graft implant site. Control was obtained by ligation of the superficial femoral artery because of severe infection which precluded reintroduction of a new graft. Five of the ruptured aneurysms presented in a thigh and three were located in a forearm. Five grafts presenting aneurysmal dilation were resected. Reimplantation of a fresh bovine graft was carried out in four patients. Both arterial and venous segments of the previously placed bovine grafts were utilized as the vascular inflow and outflow tract on two occasions. The old venous outflow tract was preserved in the remaining two patients and the proximal end of the new graft implanted into a fresh arterial segment. Simple excision without reimplantation at the site was carried out in a fifth patient. The fourteenth aneurysm developed within one month of implantation. It functioned as a hemodialysis access route for three months at which point the patient died of a cerebral hemorrhage secondary to severe hypertensive cardiovascular disease. Of interest is the observation that, in all instances of ruptured aneurysms, the bovine graft was totally unrecognizable except at the venous end. The proximal end was generally represented by a one to 2 cm graft stump and in one instance did involve the implant site. One of the electively excised aneurysms involved the brachial artery necessitating the implantation of a segment of basilic vein to maintain arterial continuity. Other Complications In addition to the foregoing complications one spontaneous outflow tract disruption was experienced 21

days after implantation of the graft. The resultant hemorrhage was controlled but necessitated termination of the graft. The failure was judged to be technical because of the selection of a basilic vein with a reduced caliber. Two patients exhibited morbid edema. One followed implantation of a graft between the femoral artery and the external iliac vein. The edema became progressively larger necessitating termination of the graft with reimplantation of a new graft. Both of these procedures were performed with resolution of the edema at the State University Hospital. The second instance of morbid edema involved an upper extremity. The graft was used for ambulatory dialysis until the patient's death secondary to uncontrolled diabetic acidosis. One graft was severely lacerated incidental to the performance of hemodialysis necessitating surgical repair. A second graft developed a hematoma following removal of the dialysis needle and likewise was successfully repaired. One patient with early thrombosis of a thigh graft developed an inguinal lymphocele which became secondarily infected with consequent graft failure. Results of Therapy Fifteen of 47 patients (32%) have died during the 30 month period ending December 31, 1975. No deaths occurred during the 6 month observation period ending June 30, 1976. The causes of death were primarily related to the complications of hypertension, cardiovascular disease, uncontrolled diabetic acidosis and a variety of terminal systemic infections. Six patients in the group had multiple grafts. Eleven grafts (16.4% of the total number of grafts placed) were functional at time of death. While on hemodialysis, 6 of the group died within two months and five died within three to 7 months after the establishment of a fistula. Three patients died within one month and a fourth died within

TABLE 2. Incidence of Aneurysm Formation in Bovine Grafts for Hemodialysis in Hypotensive and Normotensive Patients by Race

Patients with Hypertension Negro Number of patients % of total grafts %by race Number of grafts required to maintain vascular access % of grafts used Number of patients developing aneurysms % of patient group Number of grafts developing aneurysms % of group Number of grafts undergoing aneurysm formation with spontaneous rupture % of aneurysms with spontaneous rupture

13

59%

29 62%

18 38%

10o

32 48% 2 7% 2 6%

42 63% 8 28% 14 48%

25 37% 0 0%o

1

8 57%

Caucasian

6

19 40o

16 34% 55%

12

28

25% 67%

35 52% 6 32% 12 34%

17 26 2 13% 2 12%

15 22 0

7

1 50o

10 37% 0

7 58%

Total

Negro

25 6 46% 12 48%

Caucasian

Total

13% 33%

37%

Negro

Caucasian

28% 45%

0%o 0

Combined Total

Patients with Normotension

0%o 0

Total

47

67 8 17% 14

21% 8

648

MOHAIDEEN AND OTHERS

three months after graft failure despite continued peritoneal dialysis. All five diabetics in the series died within one to four months after establishment of a fistula. The fact that the survival rate in this group of 15 patients ranged from one to twelve months (averaging 3.7 months after implantation of a graft to establish a fistula for hemodialysis) attests to the far advanced state of their disease. Thirty-two (68%) of the original 47 patients admitted to the study have survived. Twenty (42.6%) patients continue on hemodialysis via functional bovine grafts. Of the 12 patients alive, but without functional bovine grafts, 7 are being maintained on hemodialysis via P.T.F.E. Goretex grafts and four are on hemodialysis via matured radiocephalic fistulae. One patient, who had three bovine grafts, the last of which failed at the end of this period of study, is being maintained on peritoneal dialysis. The 20 patients with functional bovine grafts, in addition to the 11 patients presenting functional grafts at death, constitute a total of 31 functional grafts or a 46.3% functional survival rate achieved during the three year study period. The 47 patients reported in this series constitutes 20.5% of 229 patients being maintained on the chronic hemodialysis program during the 30 month period ending December 31, 1975. The 32% fatality rate compares to a fatality rate of 25.3% or 46 deaths in 182 patients being maintained on chronic hemodialysis via any access route but excluding all patients in whom a bovine graft had been placed.

Ann. Surg.

o

November 1977

The 47 patients were subjected to 105 surgical procedures without a fatality ascribable to surgery and without loss of limb. This averages 2.2 procedures per patient. Thirteen patients with multiple grafts required 65 surgical procedures, or 5.0 procedures per patient. The number of procedures required to maintain a satisfactory access route in the surviving patients as compared to the deceased was 2.3 and 2.1 procedures respectively. Sixteen patients did not realize a continued maintenance of their bovine graft access routes despite 39 procedures performed to maintain the viability of the bovine graft. Seven of these 16 patients were converted to P.T.F.E. Goretex grafts which have continued to function. Four patients died, four are being maintained on a Brescia fistula which matured in the interval gained by utilizing the bovine graft, and one patient is being maintained on peritoneal dialysis. Seventeen primary grafts continued to function at the conclusion of the 36 month period with a survival time ranging from 7 to 24 months. Five patients had multiple bovine grafts which functioned consecutively from 15 to 36 months. In a second group of 7 patients nonfunctioning bovine grafts were replaced by P.T.F.E. Goretex grafts, which have functioned sequentially for from 12 to 36 months. Four deaths were associated with congestive heart failure in combination with other pathological entities such as pericarditis, hepatitis, chronic alcoholism and amyloidosis with septicemia. While the arterio-venous fistulae may be impugned as contributing to the

"4.|

|

_

Tfll 1 1 | 21| M | |

_

til 2 l l l l l i l

_ _

i_ 1 l

*

FIG. 1. A photomicrograph of a modified bovine graft incorporated into host connective tissue. The graft lumen is occluded by an organizing mural thrombus. The graft wall is not invaded by this inflammatory cellular reaction evident taround the graft. (hema-

toxylin-eosin x 28)

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649

FIG. 2. A highpower view of Figure 1 showing a pronounced chronic inflammatory infiltrate in the host tissues surrounding the bovine graft. The infiltrate is composed by lymphocytes and plasma cells. (hematoxylin-eosin x 160)

development of heart failure, no other instances of chronic heart failure were observed in this series. Nor is it likely that the hemodynamic effect of the fistula was the precipitating cause of heart failure in these patients. Two patients had functional fistulae for five to 6 months prior to the onset of failure and death. The remaining two patients with functional fistulae experienced thrombosis of their fistulae prior to the onset of heart failure. Discussion The feasibility of maintaining

a

satisfactory

access

route for chronic hemodialysis by the utilization of a

modified collagen arterial heterograft of bovine origin is well documented and is supported by this report. 1,2'4'5'7'811,12 While this technique is reasonably

well accepted by most patients, for some, acceptance is one of resignation coupled with despair-a seemingly endless period of multiple surgical procedures and associated discomforts. Hopefully better solutions will be forthcoming and will include increased access to kidneys for transplantation and the development of better and longer lasting prostheses especially in relation to the incidence of thrombosis and aneurysm formation. Table 1, summarizing our experience relative to graft thrombosis, indicates no substantial differences in the incidence of graft thrombosis in relation to the

site of graft placement. The differing incidence of acute and delayed graft thrombosis observed in negro

and caucasian patients is probably of significance. The occurrence

no

statistical

of true aneurysms in 8 negro patients, but in no caucasian patients, is statistically suggestive. While severe hypertensive cardio-vascular disease may be considered as an etiologic factor in aneurysm formation, the development of true aneurysms in two normotensive negro patients suggests that yet other factors were operative. The bovine grafts utilized in this series of patients are reported to exhibit minimal antigencity.3 Histologic study of recognizable segments of bovine grafts removed at surgery incidental to the excision of aneurysms occurring in said grafts revealed an infiltration of the hosts tissues immediately adjacent to the graft by variable numbers of mononuclear cells with but little to no extension of the inflammatory reaction into the graft matrix. Figures 1 and 2 are representative of these histologic changes observed in five grafts studied following excision. These histologic findings together with the apparent stability of multiple grafts implanted sequentially in 13 patients do not suggest a relationship between aneurysm formation and rejection of the heterograft. The observation that 8 negro patients or 27.6% of all negro patients, developed true aneurysms following the implantation of bovine grafts is cause for concern. The 51% incidence of

MOHAIDEEN AND OTHERS

bovine graft thrombosis and the 27.6% incidence of bovine graft aneurysm formation in negro patients has induced us to consider other materials in the hope that the incidence of these complications can be reduced. Accordingly, we have abandoned the use of bovine grafts for hemodialysis access and have undertaken a long term evaluation of the P.T.F.E. Goretex graft. To date 22 such grafts have been implanted. All but four have functioned satisfactorily for as long as 10 months. The time lapse is too short for definitive evaluation of the P.T.F.E. graft however, the preliminary impression is that the new material will prove superior to bovine heterograft.

Conclusions A 36 month survey summarizing the usefulness of 67 bovine heterografts implanted into 47 patients requiring an access route for the maintenance of chronic hemodialysis is reported. One hundred five surgical procedures were required to establish and to maintain the 67 grafts as functional hemodialysis access routes in 47 patients. Twenty patients had functional grafts at the end of the study period and 11 patients had functional grafts at death constituting 31 functional grafts or 46.3% of all grafts implanted. No primary infection or loss of life or limb attributable to a surgical procedure was experienced. Fifteen or 32% of 47 patients originally admitted to the study have died during the 30 month study period. This represents a 1.1% fall out per month or about 12.8% fall out per annum which compared to a 10.6% fall out per annum for all patients undergoing hemodialysis at our facility. A 51% incidence of bovine graft thrombosis is reported. Revascularization by thrombectomy was achieved in 52%. A 27.6% incidence of bovine heterograft true aneurysm formation is reported as occurring in negro patients with no aneurysm formation observed in caucasian patients. The use of bovine heterografts as a hemodialysis access route in hypertensive negro patients is believed contraindicated.

Ann. Surg. * November 1977

The development of better prostheses for use as hemodialysis access routes is believed to be the pivotal factor in the elimination of true aneurysm formation and the reduction of graft thrombosis.

Acknowledgments The authors thank Robert J. Flynn, Ph.D. of the Brooklyn Polytechnic Institute for his assistance in determining the statistical significance of graft thrombosis and aneurysm formation observed in this study and Roosevelt Torno, M.D. for his assistance in preparing and describing the microphotographs.

References 1. Biggers, J. A., Remmers, A. R. Jr., Glassord, D. M., et al.: Bovine Graft Fistulas in Patients with Vascular Access Problems Receiving Hemodialysis. Surg. Gynecol. Obstet., 140:690, 1975. 2. Butt, K. M. H., Rao, T. K. S., Maki, T., et al.: Bovine Heterograft as a Preferential Hemodialysis Access. Tran. Am. Soc. Artif. Intern. Organs, Vol. XX-A:339, 1974. 3. DeFalco, R. J.: Immunologic Studies of Untreated and Chemically Modified Bovine Carotid Arteries. J. Surg. Res., 10:95, 1970. 4. Haimov, M., and Jacobson, J. H., II: Experience with Modified Bovine Arterial Heterograft in Peripheral Vascular Reconstruction and Vascular Access for Hemodialysis. Ann. Surg., 180:291, 1974. 5. Johnson, J. M., Kenoyer, M. R., Johnson, K. E., et al.: The Modified Bovine Heterograft in Vascular Access for Chronic Hemodialysis. Ann. Surg., 183:62, 1976. 6. Linton, R. R.: Atlas of Vascular Surgery, Philadelphia W. B. Saunders, 421, 1973. 7. Lefrak, E. A., and Noon, G. P.: Surgical Technique for Creation of an Arteriovenous Fistula using a Looped Bovine Graft. Ann. Surg., 182:782, 1975. 8. Payne, J. E., Chatterjee, S. N., Barbour, B. H., and Berne, T. V.: Vascular Access for Chronic Hemodialysis using Modified Bovine Arterial Graft Arteriovenous Fistulas. Am. J. Surg. 128:54, 1974. 9. Rosenberg, N., Gaughran, E. R. L., Henderson, J., et al.: The use of segmental arterial implants prepared by enzymatic modification of heterologous blood vessels. Surg. Forum; 6:242, 1956. 10. Rosenberg, N.: Arterial Heterografts and Their Modifications, In S. A. Wesolowski and C. Dennis (eds.), Fundamentals of Vascular Grafting, New York, McGraw-Hill Book Co., 1963, Chap. 15. 11. Sterling, W. A., Taylor, H. L., and Diethelin, A. G.: Vascular Access for Hemodialysis by Bovine Graft Arteriovenous Fistulas. Surg. Gynecol. Obstet., 141:69, 1975. 12. Yokoyama, T., Bower, R., Chinitz, J., et al.: Experience with 100 Bovine Arteriografts for Maintenance Hemodialysis. Trans. Am. Soc. Artifi. Intern. Organs, Vol. XX-A:328, 1974.

Arterio-venous access utilizing modified bovine arterial grafts for hemodialysis.

Arterio-Venous Access Utilizing Modified Bovine Arterial Grafts for Hemodialysis A. HASSAN MOHAIDEEN, M.D., JAIRO MENDIVIL, M.D., MORRELL M. AVRAM, M...
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