Extra-anatomic Bypass of the Abdominal Aorta | NCBI

Extra-anatomic Bypass of the Abdominal Aorta: Management of Postoperative Thrombosis ROBERT W. OBLATH, M.D., RICHARD M. GREEN, M.D., JAMES A. DEWEESE, M.D., CHARLES G. ROB, M.D.

Extra-anatomic bypass of the abdominal aorta was performed in 25 patients too ill to undergo abdominal operation (Group I) and in 22 patients with graft sepsis or hemorrhage (Group II). The graft patency rate determined by life table analysis in Group I patients was 83.5% at one year and 60% at two years. The graft patency rate for Group II patients of 47% at one year was significantly lower than the patency rate for Group I patients (p < .01). Thrombectomy was attempted in 11 of the 18 grafts that occluded postoperatively. Patency was re-established by this method in nine grafts (82%), failures resulted in amputation. Recurrent occlusion of three thrombectomized grafts was treated by multiple thrombectomies with cumulative patencies up to 44.5 months. Thrombectomy was not attempted in seven occluded grafts. Two graft occlusions resulted in amputation of extremities. Contralateral axillofemoral grafts were performed in three of the patients, ipsilateral axillofemoral graft in one patient, and aortobifemoral graft in one patient. Thrombectomy is the treatment of choice for occluded extra-anatomic bypass grafts. It can be performed easily under local anesthesia. If unsuccessful, contralateral axillofemoral or femoro-femoral grafts are indicated to re-establish blood flow. E XTRA-ANATOMIC BYPASS of the abdominal aorta is a

recognized procedure for revascularizing the lower extremities of the poor risk patient with aortoiliac occlusive disease, and for the patient with technical complications involving the abdominal aorta such as hemorrhage from the proximal aortic anastomosis, aorto-enteric fistulae, and prosthetic graft sepsis." '' 20 Graft thrombosis rates as high as 28% in the first six postoperative months have, however, limited the elective use of these grafts.'0 The etiology of extraanatomic graft thrombosis has been attributed to external graft compression, the absence of healing, the absence of supporting fibrous capsule about the graft, progression of atherosclerotic disease with limitation of outflow,9 '"1 and intimal hyperplasia at the proximal anastomosis.5"6 Graft thrombectomy under local anesthesia has been suggested by both LoGerfo'0 and Mannick12 as a method of prolonging long-term patency. Presented at the Annual Meeting of the Southern Surgical Association, December 5-7 1977, Hot Springs, Virginia.

From the University of Rochester Medical Center, Department of Surgery, Rochester, New York

The records of 47 patients with 71 extra-anatomic bypasses were reviewed. The results of early thrombectomy for thrombosis of extra-anatomic bypasses were analyzed and compared with other methods of management. Materials and Methods There were 71 extra-anatomic bypasses of the aortoiliac system with 10 mm woven or knitted Dacron® grafts performed on 47 patients between April 1970 and June 1976 by the resident and attending staffs of Strong Memorial Hospital. Eight femoro-femoral, four axillobifemoral, and 59 axillofemoral grafts were inserted. Indications for operation were aorto-iliac occlusive disease in which abdominal operation was contraindicated (Group I: 25 patients, 34 extremities) or for sepsis and/or hemorrhage from the proximal abdominal aorta (Group II: 22 patients, 37 extremities). Group I was further divided by symptoms: claudication in 10 extremities, rest pain in 17 extremities, and gangrene in 7 extremities. Group II was composed of 11 patients with abdominal aortic aneurysm in which resection was technically impossible, and 11 patients who developed sepsis of a previously inserted aortic prosthesis. All patients had received antistaphylococcal antibiotics preoperatively. There were 17 males and 8 females in Group I. Females were operated on at a statistically significant earlier age than males, 57.5 years vs. 68 years (p < 0.01). There were 19 males and 3 females in Group II, both with a mean age of 65 years. Ischemic heart disease and chronic obstructive pulmonary disease were present in 80% of the total

0003-4932-78-0600-0647-0075 © J. B. Lippincott Company

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TABLE 1. Early Results of Elective Extra-anatomic Bypass of Abdominal Aorta Operative Indication

No. of Extremities

Patent

Claudication Rest pain Gangrene

10 17 7

10 (100%) 15 (88%) 5 (71%)

population. Hypertension was significantly prevalent in the female population (p < 0.01).

more

Results The grafts remained patent for the first 30 postoperative days in 88% of the extremities of Group I patients. All ten extremities operated on for claudication improved as did 20 of 24 extremities (83%) operated upon for limb salvage (Table 1). The in-hospital postoperative mortality rate was 4%. One patient developed acute tubular necrosis and gram negative sepsis and died of a myocardial infarction. One patient survived a postoperative myocardial infarction. Three patients required four major amputations. There were two graft infections (6%) both in the groin, one S. aureus involving the anastomosis, the other a superficial E. coli infection. The patient with the S. aureus infection died of sepsis (Case 2) whereas the patient with E. coli infection recovered with local antibiotic therapy and died 37 days later of an unrelated myocardial infarction (Case 1). The in-hospital mortality rate for Group II patients was 41% and was due to the high incidence of multisystem failure manifested by acute tubular necrosis, pneumonia, and gram negative sepsis. Eight patients developed ATN, one survived; seven patients developed sepsis, one survived; and, six patients developed pneumonia and two survived. There were four graft infections (10.8%) in patients without antecedent sepsis, necessitating graft removal. The first patient, (Case 3) developed a S. aureus infection of the midportion of his right axillobifemoral graft, 30 days following operation for a ruptured abdominal aortic aneurysm. This portion was excised at the time of diagnosis and a contralateral axillobifemoral graft was inserted. This patient died two years later of a myocardial infarction with a patent graft and two viable extremities. The second patient, (Case 4), developed a S. aureus infection at the left groin anastomosis eight days following bilateral axillofemoral grafts for a ruptured abdominal aortic aneurysm with a congenital left sided inferior vena cava. The left axillofemoral graft was removed 28 days after diagnosis of the infection and the patient died 12 days later with a viable left lower extremity of ATN and pneumonia. The

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third patient, (Case 5), developed a mixed S. aureus, E. coli infection at the right groin anastomosis 11 days following bilateral axillofemoral grafts for a ruptured abdominal aortic aneurysm. The graft was removed three days following diagnosis of infection, the right lower extremity was amputated above the knee one day following graft removal, and the patient died of gram negative sepsis 13 days after amputation. The fourth patient, (Case 6), developed a P. aeruginosa infection at the right groin anastomosis seven months following bilateral axillofemoral graft for an aortoduodenal fistula. An infected false aneurysm at the right groin anastomosis was resected and a new graft segment was inserted distally to the superficial femoral artery. The patient is alive with a patent graft five years following initial operation. For all graft infections five of six grafts were removed (83%), one of six limbs were lost, three of five limbs required another extra-anatomic bypass to a clean arterial segment, and three of six patients died (Table 2). The immediate operative failure rates were similar for both groups. In Group I five of 33 grafts (15%) thrombosed within the first three postoperative days, and in Group II five of 37 grafts (13.5%) thrombosed in the same time period. Of those grafts that remained patent longer than three days, the one year patency rate determined by the life table analysis of Cox and Kaplan and Meier was significantly greater in Group I patients, 83.5% than in Group II, 47%.2,9 (p < 0.01) At two years the graft patency rate in Group I patients determined by this life table analysis was 60% (Fig. 1).2 6.9 Therefore, the rate of graft thrombosis as determined by life table analysis in the electively treated patients was 16.5% for the first year and 23.5% for the second year. Postoperative graft thrombosis occurred in 18 grafts (26%); six in the immediate postoperative period, five in the first three months, tfiree in the first year, and four in the second year. Thrombectomy under local anesthesia was attempted in 11 occluded grafts (Table 3). Patency was re-established in three of five prostheses TABLE 2. Results of Treatment for Postoperative Graft Infection

Patient

Graft

Limb

Life

1 2 3 4 5

Saved Lost Lost Lost Lost Lost 5 of 6 removed

Survived Saved* Saved* Survived Lost Saved* 1 of 6 lost*

Survived Dead Survived Dead Dead Survived 3 of 6 dead (50%)

6

Total:

(83%) * Three of 5 surviving limbs required another bypass to a clean segment.

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649 and 23 months and required contralateral axillofemoral bypass grafts for limb preservation. All were successful (Table 4).

EXTRA ANATOMIC BYPASS GRAFTS LONG TERM PATENCY

240 320 400 480 DAYS POST OPERATION

FIG. 1. Long-term patency of Group I and Group by Life Table analysis.

560

11

bypass grafts

that occluded in the immediate postoperative period. The failures required amputation. The three successfully thrombectomized grafts remained patent for 17.2 months, ten days, and ten days. The latter two grafts were in a patient who died ten days after operation of a myocardial infarction. Thrombectomy was attempted on two grafts that occluded at 9.5 months and 20.5 months and although initially successful for one and two months, thrombosis recurred requiring amputation in one patient and revascularization via a contralateral axillofemoral bypass graft in the other. Three other patients with late graft occlusion at three, three, and 11 months have undergone two to five successful thrombectomies with cumulative patencies of 5.5, 18.5, and 44.5 months. Thrombectomy was not attempted in seven occluded grafts (Table 4). Three of these occurred in the early postoperative period and two required major amputation. The other four grafts occluded at four, 14, 15,

Discussion The cumulative experience with extra-anatomic bypass grafts of the abdominal aorta since their initial description in 1962-1963 by Blaisdell and Louw confirms their usefulness in providing adequate blood flow to ischemic lower extremities."'' Used electively in poor risk patients with aorto-iliac occlusive disease, we obtained an initial success rate of 83% when operation was for limb salvage and 100% when operation was for claudication. This compares favorably with the results of Mannick and Moore who reported success rates of 87 and 94%. 12,15 Moore also reports a success rate of 80% in patients with claudication.'5 Despite the high incidence of serious associated disease, our elective operative mortality rate was 4%. Others have reported a postoperative mortality rate of 2.7, 4.7 and 5%10,13,15 indicating the relative safety of this operation in the poor risk patient. In good risk patients the postoperative mortality of aorto-femoral bypass is reported as 8.6% and that for endarterectomy as 3%.14 When intra-abdominal aortic reconstruction is technically impossible, as in our Group II patients, the extraanatomic bypass graft is the only operative alternative. The postoperative mortality rate of 41% in our series and 25-100% in other series indicate the critical nature of the underlying disease process in these patients who die of multisystem failure manifested by shock, gram negative sepsis, and acute tubuiar necrosis. 10,12,13,15

Our incidence of graft infection was 6% in the elective group and 10.8% in the emergent group. This is higher than the rate of 3% reported by Szilagyi for aorto-femoral and femorofemoral bypass (51 of 1354 grafts)'8 and 3.2% reported by Jamieson, et al., for prosthetic grafts with a groin incision (ten of 315 grafts). Treatment of graft infection required removal

TABLE 3. Thrombosed Grafts Treated by Thrombectomy

Patient

Indication

Day of Thrombosis

Treatment

Result

1

Ruptured AAA

Thrombectomy X5

Patent 44.5 mo

Alive, patent grafts

2 3 4 5 6 7 8 9 10 11

Graft sepsis Ruptured AAA Ruptured AAA Claudication Rest pain Rest pain Rest pain Gangrene Gangrene Gangrene

11 mo, 13 mo, 13.5 mo, 7 mo 3 mo, 2 mo, 0.5 mo 1 day 1 day 20.5 mo 1 day 1 day 2 mo 1 day 3 mo, 2 mo 9.5 mo

Thrombectomy X3 Thrombectomy Thrombectomy Thrombectomy Thrombectomy Thrombectomy Thrombectomy Thrombectomy Thrombectomy X2 Thrombectomy

Patent 5.5 mo Patent 10 days Patent 10 days Patent 2 mo Thrombosed Patent 17.2 mo Patent 11 mo Thrombosed Patent 18.5 mo Thrombosed

Dead, patent at death Dead, patent at death Dead, patent at death Alive, additional graft. patent Amputation Thrombosed, amputation Alive, patent graft Amputation Dead, patent at death Amputation

Remarks

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TABLE 4. Thrombosed Grafts Without Thrombectomy

Patient

Indication

Day of Thrombosis

Treatment

Result

Remarks

I 2 3 4 5 6 7

Rest pain Rest pain Rest pain Rest pain Rest pain Gangrene Claudication

4 mo 15 mo 1 mo 2 mo 23 mo 1 day 14 mo

Cont. axillo femoral Ipsi, axillo femoral Bil. aorto femoral No treatment Cont. axillo femoral No treatment Cont. axillo femoral

Patent 9 mo Patent 1.5 mo Patent 1 mo Thrombosed Patent 14 mo Thrombosed Patent 39 mo

Alive, patent graft Sepsis 2° to infection Dead, patent at death Alive, additional graft thrombosed Alive, patent graft Amputation Dead, patent at death

of five of six grafts and revascularization into a clean arterial segment in three of five extremities. This resulted in limb salvage in five of six cases, and there was a mortality rate of 50%. Our high incidence of groin wound infection occurred despite the prophylactic use of antibiotics.7 Although early satisfactory results are obtained in the poor risk patient with aorto-iliac occlusive disease by extra-anatomic graft, long-term patency does not compare favorably with that of intra-abdominal bypass.4"4"7 Aorto-femoral bypass with dacron has been shown to give a 97% six year patency rate.'4 Of 102 patients undergoing aorto-iliac thromboendarterectomy, a 100% patency rate was noted in 38 patients followed five years.3 A 98% patency rate was also noted in 97 patients followed four to 36 months in the same series.3 Extra-anatomic bypass grafts have shown considerably lower patency rates. In Moore's series 60% were patent at 12 months and 50% at 18 months.'5 LoGerfo, et al., determined 74% of the axillobifemoral and 37% of axillounifemoral grafts were patent at five years.10 Unfortunately, the latter study is one where cumulative patency is measured. That is, graft thrombosis treated by successful thrombectomy is not considered a graft failure. Thus a graft is considered patent over a long period even though multiple thrombectomies have been performed. Our data has been analyzed by the life table method such that patency is described as a finite time period from operation to graft occlusion. Thrombectomy and the resulting patency period is considered a separate event. In elective cases our one year patency rate is 83.5% and our two year rate is 60%. These results are similar to other reports and likewise do not approach the patency rates described for aorto-femoral grafts or aorto-iliac thromboendarterectomy. Group II patency rates are significantly lower than either Group I rates or those reported for aortofemoral bypass or endarterectomy. High postoperative mortality in this group does not explain the lower patency rate of 47%. It may be related to a number of factors. These patients are admitted in shock and complete evaluation of peripheral pulses is often inade-

quate due to low peripheral perfusion and the necessity for rapid resuscitation and early operation. Preoperative angiography is not routine. Initial operative efforts are directed at intra-abdominal aortic repair that often results in aortic ligation. This is followed by rapid axillofemoral bypass grafting in the setting of a critically ill, deteriorating patient. Thus technique and prolonged low peripheral perfusion may combine to significantly lower patency rates in those patients who do survive. As noted above, one study calculates cumulative long-term patency in which thrombectomy provides prolongation of graft life.'0 Postoperative thrombosis has been reported in 12, 20, and 28% of cases.10'12'13 A 26% thrombosis rate is reported in this series. Most graft thromboses occur in the early postoperative months. An explanation of early graft thrombosis has been suggested by Mannick. 13 The neointima forms during this period as does the surrounding fibrous capsule. Both provide a greater capacity to eventually withstand temporary periods of reduced flow. Thrombectomy is the treatment of choice in the event of graft thrombosis. It may be done under local anesthesia and should be followed by intraoperative angiography to define distal runoff. It may be necessary to improve runoff with additional distal grafts. 10 Revascularization via contralateral axillofemoral graft or femoro-femoral graft should also be considered. In four instances flow through patent hypogastric arteries to the affected limb has resulted in limb salvage. Failure to perform a thrombectomy or additional bypass grafts resulted in amputation in five of 18 cases. References 1. Blaisdell, F. W. and Hall, A. D.: Axillary-Femoral Artery Bypass for Lower Extremity Ischemia. Surgery, 54:563, 1963. 2. Cox, D. R.: Regression Models and Life Tables (with discussion). J. R. Statist. Soc., 34:187, 1972. 3. Darling, R. C. and Linton, R. R.: Aortoiliofemoral Endarterectomy for Atherosclerotic Occlusive Disease. Surgery, 55: 184, 1964. 4. DeBakey, M. E., Crawford, E. S., Cooley, D. A. and Morris, G. C., Jr.: Surgical Considerations of Occlusive Disease of the Abdominal Aorta and Iliac and Femoral Arteries: Analysis of 803 Cases. Ann. Surg., 148:306, 1958.

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5. DeWeese, J. A. (discussion) Plechat, F. R. and Pories, W. J.: Extra-anatomic Bypasses for Aortoiliac Disease in HighRisk Patients. Surgery, 80:486, 1976. 6. Gehan, E. A.: A Generalized Wilcoxon Test for Comparing ,* Arbitrarily Single Censored Samples. Biometrika, 52:203, 1965. 7. Hunt, T. K., Alexande-, J. W., Burke, J. F. and MacLean, L. D.: Antibiotics in Surgery. Arch. Surg., 11 0: 148, 1975. 8. Jamieson, G. G., DeWeese, J. A. and Rob, C. G.: Infected Arterial Grafts. Ann. Surg., 181:850, 1975. 9. Kaplan, E. L. and Meier, P.: Non Parametric Estimation from Incomplete Observations. J. Am. Statist. Assoc. 53: 457, 1958. 10. LoGerfo, F. W., Johnson, W. C., Corson, J. D., et al.: A Comparison of the Late Patency Rates of Axillobilateral Femoral and Axillounilateral Femoral Grafts. Surgery, 81, 33, 1977. II Louw, J. H.: Splenic-to-Femoral and Axillary-to-Femoral Bypass Grafts in Diffuse Atherosclerotic Occlusive Disease. Lancet, 1401, June 29, 1963. 12. Mannick, J. A. and Nabseth, D. C.: Axillofemoral Bypass Craft. A Safe Alternative to Aortoiliac Reconstruction. N. Engl. J. Med., 278:461, 1968.

13. Mannick, J. A., Williams, L. E. and Nabseth, D. C.: The Late Results of Axillofemoral Grafts. Surgery, 68:1038, 1970. 14. Moore, W. S., Cafferata, H. T., Hall, A. D. and Blaisdell, F. W.: In Defense of Grafts Across the Inguinal Ligament: An Evaluation of Early and Late Results of Aorto-Femoral Bypass Grafts. Ann. Surg., 168:207, 1968. 15. Moore. W. S., Hall. A. D. and Blaisdell, F. W.: Late Results of Axillary-Femoral Bypass Grafting. Am. J. Surg., 122: 148, 1971. 16. Plecha, F. R. and Pories, W. J.: Extra-Anatomic Bypasses for Aortoiliac Disease in High-Risk Patients. Surgery, 80:480, 1976. 17. Szilagyi, D. E., Smith. R. F., Elmquist, J. G., et al.: Angioplasty in the Treatment of Peripheral Occlusive Arteriopathy. Arch. Surg., 90:617. 1965. 18. Szilagyi, D. E., Smith, R. F., Elliott, J. P. and Vrandecic, M. P.: Infection in Arterial Reconstruction with Synthetic Grafts. Ann. Surg., 176: 321, 1972. 19. Szilagyi, D. E., Elliott, J. P., Smith, R. F., et al.: Secondary Arterial Repair: The Management of Late Failures in Reconstructive Arterial Surgery. Arch. Surg., 110:485, 1975. 20. Vetto, R. M.: The Femorofemoral Shunt: An Appraisal. Am. J. Surg., 112:162, 1966.

Disc USSION

In his manuscript, Dr. DeWeese quite properly emphasizes dangers of infection in the subcutaneously planted graft. This is a distressing event, especially when you have done the operation on a poor-risk patient, or a patient with an infected graft from another location, and are looking for a simple procedure. The main point of the paper is that, although there is a high incidence of thrombosis, Dr. DeWeese has demonstrated that if a thrombectomy, or further attempts at revascularization are performed, a successful outcome frequently results. With this I agree. In North Carolina Memorial Hospital in Chapel Hill we performed 42 axillofemoral bypass grafts, with similar results to those just reported. Two technical points: first, the 8 mm graft works better in our hands, since the velocity of flow is greater, and, we think, has less tendency to clot. Second, the axillary to both femorals has better results than to one femoral-also, we suspect, because of the increased velocity in the long limb of the graft. One question: Does your method of analysis do your results justice' You may increase the number of grafts exposed to the risk of clotting, but in doing this you double expose the grafts that do not function, or in which you have had to do another revascularization procedure. This would not give us a true incidence of primary graft failure, which should be better than the results that you report. I think we need to emphasize that these are not the procedures of choice for aortic or iliac occlusive disease. Replacement of bypass of an aorticoiliac segment with a prosthetic graft gives excellent early and late results, and can be performed with a low mortality in a majority of these patients. Extra-anatomic bypass grafts, as just described, are for patients with infected grafts, or who are very poor risk.

DR. WILLIAM H. ED\ARDS (Nashville, Tennessee): (Slide) At the vascular meetings this past summer, we presented a series of 1700 vascular procedures of which 67 were extra-anatomic bypass; these were both femoro-femoral as well as axillo-femoral bypass grafts. Seven of these patients had to be returned to the operating room within 72 hours following the original surgery. Five of these seven were for thrombosis; two were for hemorrhage. Of the patients returned to the operating room for thrombosis, the graft was opened in only two; one requiring thrombectomy and one a profundoplasty. (Slide) In the total group of 1700 patients, there were 58 that were returned to the operating room for thrombosis with a much higher salvage rate of return of flow. The patients with aortic bypass had a higher patency rate than those with extra-anatomic bypasses or embolectomies. We agree that the patient in whom some time and effort has been invested for restoration of flow to the lower extremities should have a second effort if the patient's general condition allows this. We prefer technically to approach both suture lines at the second operation feeling that there is probably some problem at a suture line or at the anastomosis which has caused the thrombosis. Fortunately, we have not had a high incidence of sepsis and consequently have not had to perform extra-anatomic bypasses for that reason. DR. GEORGE JOHNSON, JR. (Chapel Hill, North Carolina): The extra-anatomic bypass graft has certainly contributed to our management of arterial occlusion. They are not only useful in the axillogemoral and the femoro-femoral position, but also between the two axillary arteries and the carotid and subclavian arteries. We are able to take blood from one vascular system to give to another, because the flow through the arteries depends more on the peripheral resistance of the vascular bed than it does on the size of the artery. Thus each system has considerable reserve. The "rob Peter to pay Paul" principle works very well, as long as Peter, the artery that's being robbed, has no proximal obstruction. It is, however, possible to cause distal ischemia in the system from which you take the blood, if proximal arterial occlusion is present. We have seen this in two cases: thus we have made the good leg bad.

DR. W. STERLING EDWARDS (Albuquerque, New Mexico): We have used these techniques infrequently, for two reasons. First, we have been very fortunate in not having many infected grafts. Secondly, we've been rather reluctant to use axillo-femoral grafts on elective patients, since the reported long-term patencies have been rather poor. Therefore, I have more questions than comments. My first question is: Was there any difference in patency rate, depending on whether a woven or knitted graft was used? It is stated in the manuscript that both types were used with equal frequency.