In situ arterial allografts: a new treatment for aortic prosthetic infection

Systematic Review and Meta-Analysis on the Management of Open Abdominal Aortic Graft Infections

OBJECTIVE

Aortic graft infection (AGI) is a disastrous complication with an incidence of 0.2-6% in operated patients. With little or no high quality evidence, the best treatment option remains unclear. Therefore, the literature on the management of open abdominal AGI was systematically reviewed to determine optimal treatment.

METHODS

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review and meta-analysis was conducted for AGI. MEDLINE, Embase, and the Cochrane Database of Systematic Reviews were searched. Methodological quality was assessed using the Methodological Index for Non-randomised Studies (MINORS) score. Primary outcomes were 30 day mortality and one year survival. Secondary outcomes were survival, infection recurrence, limb salvage, and graft patency.

RESULTS

Of 1574 studies identified, 32 papers were included in the study. The overall quality of the studies was moderate, with an average MINORS score of 11.9. Pooled overall 30 day mortality and one year survival were 13.5% (95% CI 10.5-16.4) and 73.6% (95% CI 68.8-78.4), respectively. The lowest 30 day mortality and highest one year survival were found for in situ repair compared with extra-anatomic repair and for prosthetic grafts compared with venous grafts or arterial allografts. The infection recurrence rate was highest for prosthetic grafts.

CONCLUSIONS

There is a lack of well designed, qualitative comparative studies making conclusive recommendations impossible. The current best available data suggests that partial graft removal should be avoided and the lowest 30 day mortality and best one year survival are achieved with in situ repair using prosthetic grafts. Initiatives such as the MAGIC database to collaboratively collect prospective data are an important step forward in obtaining more solid answers on this topic.

In vivo detection of Staphylococcus aureus in biofilm on vascular prostheses using non-invasive biophotonic imaging

OBJECTIVES

Biophotonic imaging was compared to standard enumeration method both for counting Staphylococcus aureus in biofilm and bacterial susceptibility tests of different graft materials.

DESIGN

Prospective, randomized, controlled animal study.

MATERIAL AND METHODS

Five types of vascular grafts were placed subcutaneously in 35 mice and challenged with bioluminescent S. aureus. The mice were divided into equal groups as follows: group A (polyester), group B (polytetrafluoroethylene), group C and D (two types of silver acetate-coated polyester) and group E (bovine pericardium). Controls were given only the bacteria. The bioluminescence signal of S. aureus, able to predict number of viable bacteria in biofilm without any manipulation, was measured at different time points. Five days postinfection, regular cultures of adherent bacteria on grafts were obtained. Comparative analyses between bioluminescence activity and culture enumeration were performed.

RESULTS

The number of viable bacteria on silver-coated prostheses was the slightest, indicating superior bacterial resistance. The density of bacteria on polytetrafluoroethylene and polyester was comparable, with a non-significant advantage for polytetrafluoroethylene. Moreover, bioluminescence detected the number of viable S. aureus in biofilm more exactly compared to enumeration of bacteria.

CONCLUSION

Bioluminescence imaging can be considered a useful tool to characterize susceptibility of any graft material to bacterial biofilm prior to implantation.

Fresh Arterial Grafts as Conduits for Vascular Reconstructions in Transplanted Patients

OBJECTIVES

To assess the outcome of arterial allografts in patients receiving organ transplantation.

DESIGN

From October 1997 to June 2005, we used fresh arterial allografts as vascular conduits in 21 patients for the treatment of claudications (10), abdominal aortic aneurysm (6), complicated renal transplantation (2), acute lower extremity ischemia (2) and gangrene (1). At the time of the vascular procedure, ten of the patients (Group A) had already undergone organ transplantation. The mean follow up period was 32 months for renal and 37 months for heart recipients, respectively. In 11 patients (Group B), the vascular reconstruction was undertaken simultaneously with the renal transplantation. The mean follow up period was 49 months.

RESULTS

There was no arterial allograft related deaths. No signs of arterial graft infection or requirement for secondary intervention (angioplasty and/or thrombolysis) were observed during the follow up period.

CONCLUSIONS

Our experience suggests that it is possible to use fresh arterial allografts in the treatment of arterial occlusive disease or abdominal aortic aneurysm, both in already transplanted patients and simultaneously with organ transplantation, with good results.

Fresh and Cryopreserved Arterial Homografts: Immunological and Clinical Results

INTRODUCTION

This prospective study defined the immunological and clinical results after fresh and cryopreserved arterial homograft replacement due to graft infection.

MATERIALS AND METHODS

Thirty patients who underwent ABO-compatible homograft transplantation were studied for anti-human leukocyte antigen (HLA): antibody production and CD3- and CD4- versus CD8-positive lymphocyte subsets. Nine patients (30%) received immunosuppressive treatment with cyclosporine (1 to 3 mg/kg/d). Immunological studies were performed preoperatively, and early (1, 3, 7 days) and late (1, 3, 6, 12, 24, 36, 48 months) during follow-up. Abdominal computed tomography scans were performed postoperatively at 1, 6, 12, 24, 36, and 48 months of follow-up.

RESULTS

Preoperatively, antibodies were not detected. Postoperatively, a progressive increase in percent panel reactive antibodies was observed in all patients 1 month after the transplant. There were no difference between fresh and cryopreserved homografts. The antibody response among patients treated with cyclosporine was less pronounced and delayed. Recipient antibodies were directed against donor-specific antigens. During the immediate postoperative period (1, 3, 7 days) there was a slight increase in CD3- and CD4-positive T lymphocytes and a concomitant decrease in the CD8 subset. Later, CD3 and CD4 progressively decreased and the CD8 set increased. Clinically, no patients had signs of recurrent infection upon late follow-up. Four patients died (13%), but only one death was homograft-related (rupture of the graft). At 2-year follow-up, two patients showed stenotic lesions due to chronic rejection. Clinically, no differences were noted between fresh and cryopreserved homografts, or between patients treated with or without cyclosporine.

CONCLUSIONS

Fresh and cryopreserved arterial homografts are immunogenic; they induce a strong anti-HLA antibody response, similar to chronic rejection.

Quantitative reduction of methyl tetrazolium by fresh vein homograft biopsies in vitro is an index of viability

OBJECTIVE

The color density of the methyl tetrazolium (MTT) test is proportional to mitochondrial enzyme activity thus reflecting cellular viability. The aim was to evaluate the MTT test as a viability assay for vein homograft studies.

MATERIALS AND METHODS

Fresh intact vein samples were harvested during multi-organ procurement. The reliability of the MTT assay was tested by a fluorescent dye combination (1 microg/ml propidium iodide PI and 4 microM/ml SYTO-16 stains). The enzyme kinetics of the reaction was also investigated. The optimal reagent concentration, biopsy size and incubation period were established.

RESULTS

There was a linear relationship between the vein homograft's weight and the pigment production activity. A nonspecific reaction (8.6%) was observed in negative controls. The MTT cleavage up to 0.1% (w/v) follows the Michaelis kinetics. The Michaelis constant (2,805 +/- 130 microM), the maximal velocity (196 +/- 2.2 x 10(-5 )microM s(-1)) and the velocity constant (6.98 +/- 0.2 x 10(-7) s(-1)) was calculated. The viability assessed by fluorescent dyes simultaneously visualized the live/dead cell ratio, which can be calculated by image analysis software.

CONCLUSION

The use of MTT in colorimetric assays offers high sensitivity. The assay is simple, inexpensive, and reproducible in vein homograft studies.

Preservation of Vein Allograft Viability during Long-Term Storage

BACKGROUND

The aim of this study was to compare the vein allograft viability following cryopreservation with that remaining after prolonged refrigerated storage.

MATERIALS AND METHODS

Great saphenous vein biopsies had been cryopreserved, and the samples were divided into two matched groups and stored in tissue culture medium for 42 days at +4 degrees C, either with or without regular medium replacement. Each vein allograft was biopsied and assayed for viability every third day by the methyltetrazolium reduction assay. Viability indexes of vein allografts harvested from brain-dead multi-organ donors and from cadavers whose warm ischemic periods were maximally 24 h were also compared.

RESULTS

Vein allografts stored for 42 days at +4 degrees C showed a similar viability (58.9 +/- 1.2%) to that of cryopreserved veins (59.7 +/- 2.3%). This was true even when cryopreserved and thawed allografts were subjected to 3 days of post-thaw incubation under presumably favorable conditions (58.7 +/- 1.6%). There was no viability index difference between the samples with medium replaced and not replaced and the specimens harvested from two different donor groups.

CONCLUSIONS

Long-term storage of vein allografts at +4 degrees C is a valuable option for regular banking practice. Sufficient amounts can be procured from cadavers similar to tissue donors.

Use of superficial femoral artery to treat an infected great vessel prosthetic graft

We report a patient treated for infection of an ascending aorta to bilateral common carotid artery bypass graft. The superficial femoral arteries were used for the reconstruction after local treatment failed. The patient is free from infection and the grafts are patent 4 years after operation. We believe this is the only report in the literature in which the superficial femoral arteries were used to reconstruct an infected great vessel graft.

Aortoiliac stent graft infection: current problems and management

Aortic stent graft infection is uncommon. Most cases have been described anecdotaly in single-case reports. After observing one case in our experience, we decided to review the literature and contact centers performing endovascular aortic repair to determine the frequency, risk factors, and current treatment of stent graft infection. The literature was reviewed and the authors of identified articles were contacted for further information. In addition, 40 centers specializing in endovascular treatment were contacted by means a dedicated questionnaire. A total of 65 aortic stent graft infections were identified, including 43 reported cases and 22 previously unpublished cases that were observed at specialized centers. Stent grafts were implanted in the aorta in 50 cases and in the iliac artery in 15 cases. The frequency of infection was 0.43%. The gender ratio was 4:1 (M:F). Twenty-three percent of patients had immunodeficiency factors. Placement was performed in an interventional radiology suite in 62.5% of cases and in a sterile operating theater in 37.5%. Also, 35.5% of patients underwent other vascular procedures during the course of study and 29.2% stent grafts benefited from adjuvant endovascular procedures. Infection was classified as low grade in 35.4% of patients and high grade in 64.6%. Thirty-one percent of infections were associated with aortoenteric fistula. The offending microorganism was Staphylococcus aureus in 54.5% of cases. Treatment was conservative in 18% of cases and surgical in 82%. Surgical treatment consisted of stent graft removal followed by either extraanatomical bypass (59.5%) or in situ prosthetic reconstruction (40.5%). Mortality was 18% overall, 36.4% after conservative treatment and 14% after surgical treatment ( p = 0.083). Mortality was 16% after surgical treatment with extraanatomical bypass vs. 5.8% surgical treatment with in situ reconstruction. From these results we conclude that stent graft infection is an uncommon occurrence associated with poorly defined risk factors. Surgical treatment with complete excision of the infected stent graft followed by in situ reconstruction provides the best outcome. Establishment of a multicenter register to record such complications is needed to confirm the findings of this study.

Allograft replacement for infrarenal aortic graft infection: early and late results in 179 patients

OBJECTIVES

We evaluated early and late results of allograft replacement to treat infrarenal aortic graft infection in a large number of patients and compared the results in patients who received fresh allografts versus patients who received cryopreserved allografts.

METHODS

From 1988 to 2002 we operated on 179 consecutive patients (mean age, 64.6 +/- 9.0 years; 88.8% men). One hundred twenty-five patients (69.8%) had primary graft infections, and 54 patients (30.2%) had secondary aortoenteric fistulas (AEFs). Fresh allografts were used in 111 patients (62.0%) until 1996, and cryopreserved allografts were used in 68 patients (38.0%) thereafter.

RESULTS

Early postoperative mortality was 20.1% (36 patients), including four (2.2%) allograft-related deaths from rupture of the allograft (recurrent AEF, n = 3), all in patients with fresh allografts. Thirty-two deaths were not allograft related. Significant risk factors for early mortality were septic shock (P <.001), presence of AEF (P =.04), emergency operation (P =.003), emergency allograft replacement (P =.0075), surgical complication (P =.003) or medical complication (P <.0001), and need for repeat operation (P =.04). There were five (2.8%) nonlethal allograft complications (rupture, n = 2; thromboses, which were successfully treated at repeat operation, n = 2; and amputation, n = 1), all in patients with fresh allografts. Four patients (2.2%) were lost to follow-up. Mean follow-up was 46.0 +/- 42.1 months (range, 1-148 months). Late mortality was 25.9% (37 patients). There were three (2.1%) allograft-related late deaths from rupture of the allograft, at 9, 10, and 27 months, respectively, all in patients with fresh allografts. Actuarial survival was 73.2% +/- 6.8% at 1 year, 55.0% +/- 8.8% at 5 years, and 49.4% +/- 9.6% at 7 years. Late nonlethal aortic events occurred in 10 patients (7.2%; occlusion, n = 4; dilatation < 4 cm, n = 5; aneurysm, n = 1), at a mean of 28.3 +/- 28.2 months, all but two in patients with fresh allografts. The only significant risk factor for late aortic events was use of an allograft obtained from the descending thoracic aorta (P =.03). Actuarial freedom from late aortic events was 96.6% +/- 3.4% at 1 year, 89.3% +/- 6.6% at 3 years, and 89.3% +/- 6.6% at 5 years. There were 63 late, mostly occlusive, iliofemoral events, which occurred at a mean of 34.9 +/- 33.7 months in 38 patients (26.6%), 28 of whom (73.7%) had received fresh allografts. The only significant risk factor for late iliofemoral events was use of fresh allografts versus cryopreserved allografts (P =.03). Actuarial freedom from late iliofemoral events was 84.6% +/- 7.0% at 1 year, 72.5% +/- 9.0% at 3 years, and 66.4% +/- 10.2% at 5 years.

CONCLUSIONS

Early and long-term results of allograft replacement are at least similar to those of other methods to manage infrarenal aortic graft infections. Rare specific complications include early or late allograft rupture and late aortic dilatation. The more frequent late iliofemoral complications may be easily managed through the groin. These complications are significantly reduced by using cryopreserved allografts rather than fresh allografts and by not using allografts obtained from the descending thoracic aorta.

In situ revascularization with silver-coated polyester grafts to treat aortic infection: early and midterm results

PURPOSE

In this prospective study we analyzed the immediate and midterm outcome in patients with abdominal aorta infection (mycotic aneurysm, prosthetic graft infection) managed by excision of the aneurysm or the infected vascular prosthesis and in situ replacement with a silver-coated polyester prosthesis.

METHODS

From January 2000 to December 2001, 27 consecutive patients (25 men, 2 women; mean age, 69 years) with an abdominal aortic infection were entered in the study at seven participating centers. Infection was managed with either total (n = 18) or partial (n = 6) excision of the infected aorta and in situ reconstruction with an InterGard Silver (IGS) collagen and silver acetate-coated polyester graft. Assessment of outcome was based on survival, limb salvage, persistent or recurrent infection, and prosthetic graft patency.

RESULTS

Twenty-four patients had prosthetic graft infections, graft-duodenal fistula in 12 and graft-colonic fistula in 1; and the remaining 3 patients had primary aortic infections. Most organisms cultured were of low virulence. The IGS prosthesis was placed emergently in 11 patients (41%). Mean follow-up was 16.5 months (range, 3-30 months). Perioperative mortality was 15%; all four patients who died had a prosthetic graft infection. Actuarial survival at 24 months was 85%. No major amputations were noted in this series. Recurrent infection developed in only one patient (3.7%). Postoperative antibiotic therapy did not exceed 3 months, except in one patient. No incidence of prosthetic graft thrombosis was noted during follow-up.

CONCLUSION

Preliminary results in this small series demonstrate favorable outcome with IGS grafts used to treat infection in abdominal aortic grafts and aneurysms caused by organisms with low virulence. Larger series and longer follow-up will be required to compare the role of IGS grafts with other treatment options in infected fields.

Ten-year experience in autogenous reconstruction with the femoral vein in the treatment of aortofemoral prosthetic infection

OBJECTIVE

to study the short and long term effectiveness of in situ replacement of infected aortic grafts with the lower extremity deep veins.

METHODS

forty-nine patients operated on for infrarenal aortic graft infection since 1990 were studied. Diagnosis of infection was based on clinical signs, bacteriological tests and typical findings on CT scan and leukocyte scan. The surgical treatment consisted in harvesting the femoral vein, total graft excision, thorough debridement and in situ reconstruction with the femoral veins. After discharge, the patients were followed at 6 monthly intervals with clinical examination, duplex and/or CT scan.

RESULTS

there were four in-hospital deaths (8%). One patient required above-knee amputation (2%) and there were two graft limb occlusions (4%). With a mean follow-up 41 months, another 13 patients died, unrelated to the operation (29%). There were no late amputations and only two late graft limb stenoses (4%). We have a 5 year survival rate of 60%, a 5 year limb salvage rate of 98%, and a 5 year primary patency rate of 91%. There were no cases of aneurysmal dilatation of vein grafts and no incidence of reinfection.

CONCLUSION

in situ reconstruction with the lower extremity deep veins is in the long term a safe and attractive alternative in the treatment of infrarenal aortic graft infection.

Endovascular repair of aortic allograft aneurysmal degeneration: a case report

Aortoenteric graft fistula remains a dreadful complication of aortic surgery. Good results have been reported using in situ graft replacement with arterial allografts. Late aneurysmal degeneration of the graft itself may necessitate further repair. We report the case of such an aneurysmal degeneration 7 years after implantation of the allograft. Endovascular repair was performed with a Vanguard device; complete exclusion was obtained immediately. At 6-month follow-up, the patient was alive and well. Duplex and computed tomography scans showed an excluded aneurysm with a slight reduction in size. Endovascular stent grafting may be a therapeutic option for treating patients with late allograft degeneration.

Use of superficial femoropopliteal vein for suprainguinal arterial reconstruction in the presence of infection

BACKGROUND

Conventional treatment of mycotic aneurysms or graft infections of the aortoiliac segment by in situ or extra-anatomic prosthetic reconstruction has a high mortality and morbidity rate, with a substantial risk of persistent graft infection. The use of autologous vein may reduce this.

METHODS

Eleven patients with suprainguinal arterial infections including two with mycotic aortic aneurysms, four with aortic graft infections, four infected femorofemoral grafts and an infected axillofemoral graft were treated by debridement and in situ reconstruction with autologous superficial femoropopliteal vein. All patients received appropriate antibiotic therapy and were followed by regular postoperative duplex imaging. Preoperative femoral vein duplex imaging was performed in eight of the 11 patients.

RESULTS

Ten of the 11 patients survived with a functioning graft and without limb loss or evidence of infection at 4-33 months. One patient died from myocardial infarction after operation. Three patients had minor swelling of one leg. Four patients required subsequent angioplasty of anastomotic stenoses detected by duplex surveillance.

CONCLUSION

Superficial femoropopliteal vein is an excellent conduit for suprainguinal reconstruction in the presence of infection. Duplex imaging is useful for confirming the suitability of deep veins for use as a graft and for postoperative surveillance.

Immune response following fresh arterial homograft replacement for aortoiliac graft infection

INTRODUCTION

this prospective study defines the immune response to fresh arterial homograft replacement for graft infection.

MATERIALS AND METHODS

ten patients who underwent ABO-compatible homograft transplantation were studied for anti-HLA antibody production, and CD3-CD4-CD8-positive lymphocytes subset. Immunological studies were performed preoperatively, and at early (1, 3, 7 days) and late (1, 3, 6, 12, 18, 24 months) follow-up. All patients received immunosuppressive treatment with cyclosporine (1-3 mg/kg/day). Abdominal CT scans were performed postoperatively at the 1, 6, 12, 18, 24 months follow-up.

RESULTS

preoperatively, antibodies could not be detected. Postoperatively, as from 1st month post-transplant, a progressive increase in % PRA was observed in all patients, up to the 12th month of follow-up. Subsequently, at 18 and 36 months, a progressive decrease in % PRA was detected. Data showed that the recipient antibodies were directed against donor-specific antigens. During the immediate postoperative period (1, 3, 7 days) CD3- and CD4-positive T lymphocytes slightly increased, whereas CD8 simultaneously decreased. Later, CD3 and CD4 progressively decreased and CD8 increased. Clinically, all patients were cured of infection at late follow-up. CT scans showed thickening of the aortic wall (range: 2.5-4.5 mm), with no signs of aneurysmal degeneration.

CONCLUSIONS

fresh arterial homografts are immunogenic. Implanted homografts induce a strong anti-HLA antibody response, similar to chronic rejection, in spite of immunosuppressive treatment.

The results of in situ prosthetic replacement for infected aortic grafts

BACKGROUND

Treatment of aortic graft infection with graft excision and axillofemoral bypass may carry an increased risk of limb loss, aortic stump blowout, and pelvic ischemia. A review of patients with aortic graft infection treated with in situ prosthetic graft replacement was undertaken to determine if mortality, limb loss, and reinfection rates were improved with this technique.

METHODS

The clinical data of 25 patients, 19 males and 6 females, with a mean age of 68 years (range 35 to 83), with aortic graft infection, treated between January 1, 1989, and December 31, 1998, by in situ prosthetic graft replacement were reviewed. Follow-up was complete in the 23 surviving patients and averaged 36 months (range 4 to 103).

RESULTS

Twenty aortofemoral, 3 aortoiliac, and 2 straight aortic graft infections were treated with excision and in situ replacement with standard polyester grafts in 16 patients (64%), or with rifampin-soaked collagen or gelatin-impregnated polyester grafts in 9 patients (36%). Fifteen patients (60%) had aortic graft enteric fistulas, 8 patients (32%) had abscesses or draining sinuses, and 2 patients (8%) had bacterial biofilm infections. Thirty-day mortality was 8% (2 of 25). There were no early graft occlusions or amputations. There was one late graft occlusion. There were no late amputations. The reinfection rate was 22% (5 grafts). All reinfections occurred in patients operated upon for occlusive disease. Only one reinfection occurred in the rifampin-soaked graft group (11% versus 29%, P = NS). Reinfection tended to be lower in patients with aortoenteric fistulas and without abscess. Autogenous tissue coverage provided statistically significant protection against reinfection. There were no late deaths related to in situ graft infection.

CONCLUSIONS

Patients treated with in situ graft replacement had an 8% mortality and 100% limb salvage rate. Reinfection rates were similar to those of extra-anatomic bypass, but a trend of lower reinfection rates with rifampin-impregnated grafts was apparent. Patients with aortoenteric fistula and without abscess appear to be well treated by the technique of in situ prosthetic grafting and autogenous tissue coverage.