Aortic and peripheral prosthetic graft infection: differential management and causes of mortality

A Systematic Review of In-situ Aortic Reconstructions for Abdominal Aortic Graft and Endograft Infections: Outcomes of Currently Available Options for Surgical Replacement

BACKGROUND

This review synthetizes recent literature about in-situ aortic reconstructions for abdominal aortic graft or endograft infections (AGEIs), aiming to report outcomes individually related to currently available vascular substitutes (VSs).

METHODS

We performed a systematic review of all published literature from January 2005 to December 2022. We included articles reporting on open surgical treatment of abdominal AGEIs, with removal of the infected graft and in-situ reconstruction with biological or prosthetic material. Articles not distinguishing between abdominal and thoracic aortic-related outcomes were excluded, as well as studies reporting on cumulative in-situ and extra-anatomic reconstruction results.

RESULTS

Of 500 records identified through database searching (Pubmed: 226; Embase: 274), 8 of them were included in the present review. Overall, 30-days mortality rate was 8.7% (25/285), while the most frequent early complications were respiratory adverse events (46/346, 13.3%) and renal function deterioration (26/85, 30%). In 250/350 cases (71.4%), a biological VS was utilized. In 4 articles, the outcomes of different types of VSs were presented jointly. Patients analyzed in the remaining 4 reports were sorted in a "biological" and a "prosthetic" group (BG and PG). The cumulative mortality rate of the BG and PG were 15.6% (33/212) and 27% (9/33), respectively, while graft reinfection was 6.3% (15/236) in the BG, and 9% (3/33) in the PG. The cumulative mortality rate reported in articles focused on autologous veins was 14.8% (30/202), while their 30-days reinfection rate was 5.7% (13/226).

CONCLUSIONS

Since abdominal AGEIs are uncommon conditions, literature focused on direct comparison between different types of VSs is scarce, particularly when related to materials other than autologous veins. Although we found a lower overall mortality rate in patients treated with biological material or with autologous veins only, in recent reports prosthesis provide promising results in terms of mortality and reinfection rate. However, none of the available studies distinguish and compares different types of prosthetic material. Large multicenter studies are advisable, especially focused on different types of VSs and their comparison.

Endovascular Management of Bleeding Aortoenteric Fistula May be Feasible as a Definitive Repair

Aorto-enteric fistula (AEF) is a complication with devastating sequelae and significant morbidity. Although open surgery remains primary treatment endovascular approach may be used as a temporary bridge but rarely as a definitive therapy. We present a case of a patient who presented with a secondary AEF, due to hemodynamic instability we chose to treat the fistula with an aortic endograft. The patient underwent bowel resection due to bowel obstruction with omental patch over the aortic rent, 6 weeks of antibiotics. Patient is now at 8-year follow-up without evidence of infection. Although there is scarce literature on this topic, endovascular treatment of bleeding AEF may be feasible as a definitive option. Due to high risk of graft infection we recommend close observation and suppressive antibiotics.

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.

Vascular Graft Infections: An update

Vascular graft infection is a devastating complication of vascular reconstructive surgery. The infection can occur early in the postoperative period and is largely due to intraoperative contamination or by contiguous extension from a nearby infection. It can also occur years after implantation. Staphylococci remain the most common organisms and biofilm production makes eradication difficult. Factors commonly reported to predispose to vascular graft infection are periodontal disease, nasal colonization with Staphylococcus aureus, bacteremia, certain graft characteristics, diabetes mellitus, postoperative hyperglycemia, location of the incision, wound infection, and emergency procedure. Management consists of antibiotic and surgical therapy. Preventive methods are described.

[Aorto-bifermoral grafs infection due to Candida parapsilosis. An unusual pathogen]

BACKGROUND

Aorto-enteric fistula is a rare and potentially lethal entity. Its presentation may be as an enteric-paraprosthetic fistula, due to injury in the gut caused by direct contact with the vascular prosthesis.

OBJECTIVE

We report a case of enteric-paraprosthetic fistulae with the unusual finding of Candida parapsilosis as the only isolated pathogen.

CLINICAL CASE

A 65-year-old male, smoker, with aortobifemoral revascularisation with dacron due to aortoiliac occlusive disease, and re-intervention for thrombosis of left arm at 6 months. Hospitalisation at 22 months was required due to a toxic syndrome, which was diagnosed as enteric-paraprosthetic fistulae after complementary studies. The graft was removed and an extra-anatomic revascularisation was performed. Microbiology specimens taken from the duodenal segment in contact with the prosthesis showed the prosthetic segment and peri-prosthetic fluid were positive to C. parapsilosis.

DISCUSSION

The finding of C. parapsilosis in all cultures taken during surgery, along with negative blood cultures and no other known sources of infection, is of interest. It is an unusual pathogen with low virulence and limited as regards other Candida species. Our patient had no clinical data common to cases of infection with C. parapsilosis, and the mechanism of graft infection is unknown.

CONCLUSION

Graft infection by C. parapsilosis may be anecdotal. However, its consequences can also be severe. Microbiological tests can be useful to adjust antimicrobial therapy in the post-operative period, but their usefulness for determining the aetiology is doubtful, as it may be just an incidental finding.

Randomized Study of Noninferiority Comparing Prosthetic and Autologous Vein Above-Knee Femoropopliteal Bypasses

BACKGROUND

The main aim of this study was to compare the 5 years rates of secondary patency of above-knee femoropopliteal revascularizations with autologous veins or prosthetic grafts. The secondary objectives were to compare the rates of primary patency, limb salvage, morbidity, and mortality between the 2 groups.

METHODS

This was a single-blind randomized study of noninferiority (ratio 1:1), carried out in 11 centers of vascular surgery with 2 parallel groups between July 2002 and November 2005. Follow-up finished in May 2011. The monitoring protocol included a clinical examination and an ultrasound control at 1 month, 3 and 6 months, then annually.

RESULTS

One hundred patients were included and randomized in the study, 52 in the prosthetic group and 48 in the autologous vein group. Four patients randomized in the vein group received a prosthetic graft. No patient was excluded from the analysis. In the in intent-to-treat analysis, the 5 years secondary patency was 84.6% in the prosthetic group (IC 95%, 71.9-93.1) and 70.8% in the autologous vein group (IC 95%: 55.9-83.1), and the difference in secondary patency between the prosthetic and the autologous vein groups was 13.8% (IC 95%, -4.4 to 32.0). In the under treatment analysis, the 5 years secondary patency was 96.2% among patients receiving a prosthesis (IC 95%, 80.4-99.9) and 90.5% among patients receiving an autologous vein (IC 95%, 66.9-98.9), and the difference in the rate of patency between prostheses and veins was 5.7% (IC 95%, -13.2 to 24.6). Although there was no significant difference at 5 years, the death rate and the rate of amputation were higher in the prosthetic group.

CONCLUSIONS

Although it is impossible to conclude definitely to the noninferiority of prosthetic bypass compared with venous bypass because of the insufficient number of inclusions, this randomized study nevertheless showed at 5 years the satisfactory results obtained with prostheses compared with autologous vein for above-knee femoropopliteal bypasses.

Tolerability of High Doses of Daptomycin in the Treatment of Prosthetic Vascular Graft Infection: A Retrospective Study

INTRODUCTION

In treatment of prosthetic vascular graft infection (PVGI), appropriate antimicrobial treatment is crucial for controlling the septic process and preventing re-infection of the new graft. Glycopeptides are the mainstay of treatment for device-related infections by methicillin-resistant Staphylococcus aureus strains, but with some limitations, especially concerning vancomycin-intermediate and glycopeptide-intermediate S. aureus. We report our experience using a high dose of daptomycin (DAP) for treatment of PVGI.

METHODS

We reviewed medical reports of 26 patients treated with high doses of DAP (>8 mg/kg) and beta-lactams/aminosides for PVGI, defined as positive bacterial culture of intraoperative specimens or blood samples and/or clinical, biological, and radiological signs of infection. Clinical success was defined by resolution of all clinical signs at the end of follow-up, without the need for additional antibiotic therapy, and/or negative culture in case of new surgery.

RESULTS

Cultures of intraoperative samples were positive in 21 patients (80.8%). Blood and intraoperative cultures were concomitantly positive in 10 patients. The main microorganism identified in microbiological samples was S. aureus (n = 18). Surgery was performed in 23 patients (88.4%). The mean duration of the DAP regimen was 12.3 ± 11.9 days. DAP was discontinued in 26 patients [need to switch to microbiological results (n = 19), bacterial pneumonia (n = 2), and increased creatine phosphokinase levels (n = 4)]. One patient had myalgia, while 9 received concomitant statins.

CONCLUSION

High-dose DAP therapy shows a satisfactory toxicity profile even in severely ill patients with multiple comorbidities, and may favorably compete with vancomycin, especially concerning the risk of induced nephrotoxicity.

Factors predictive of treatment failure in staphylococcal prosthetic vascular graft infections: a prospective observational cohort study: impact of rifampin

BACKGROUND

There exists considerable debate concerning management of prosthetic vascular graft infection (PVGI), especially in terms of antimicrobial treatment. This report studies factors associated with treatment failure in a cohort of patients with staphylococcal PVGI, along with the impact of rifampin (RIF).

METHODS

All data on patients with PVGI between 2006 and 2010 were reviewed. Cure was defined as the absence of evidence of infection during the entire post-treatment follow-up for a minimum of one year. Failure was defined as any other outcome.

RESULTS

84 patients (72 M/12 F, median age 64.5 ± 11 y) with diabetes mellitus (n = 25), obesity (n = 48), coronary artery disease (n = 48), renal failure (n = 24) or COPD (n = 22) were treated for PVGI (median follow-up was 470 ± 469 d). PVGI was primarily intracavitary (n = 47). Staphylococcus aureus (n = 65; including 17 methicillin-resistant S. aureus) and coagulase-negative Staphylocococcus (n = 22) were identified. Surgical treatment was performed in 71 patients. In univariate analysis, significant risk factors associated with failure were renal failure (p = 0.04), aortic aneurysm (p = 0.03), fever (p = 0.009), aneurysm disruption (p = 0.02), septic shock in the peri-operative period (p = 0.005) and antibiotic treatment containing RIF (p = 0.03). In multivariate analysis, 2 variables were independently associated with failure:septic shock [OR 4.98: CI 95% 1.45-16.99; p=0.01] and antibiotic containing rifampin [OR: 0.32: CI95% 0.10-0.96; p=0.04].

CONCLUSION

Results of the present study suggest that fever, septic shock and non-use of antibiotic treatment containing RIF are associated with poor outcome.

[Aortodigestive fistula and septic wound of the lower leg. A case report]

An aortodigestive fistula can be revealed by a peripheral septic wound when patient have aortic endovascular prosthesis. Our clinical case is about a 69-year-old patient with an abscess of the lateral aspect of his left lower limb. He has been treated few years ago for an aorto-abdominal anevrysm by an aortobifemoral prosthesis. In spite of a negative initial assessment for an aortodigestive fistula, anaerobic germs were found into the abscess. The initial treatment associated debridement, negative pressure therapy, dermal substitute and a split thickness skin graft for the loss of cutaneous substance. Months later, in front of an unexplained skin healing delay and fever, we realised new assessment bringing to light an aortodigestive fistula. Furthermore, the local bacterial samples from the wound and the hemocultures found both a lot of Escherichia Coli. The change of the aorto-bifemoral prosthesis and the cure of the aortodigestive fistula allowed the complete healing of the loss of cutaneous substance of the leg. The aortodigestive fistulas have a very high mortality. Because of their difficult diagnosis, their clinical suspicion has to start a complete medical assessment. Every septic wound when patients have vascular prosthesis is suggestive of an aortodigestive fistula.

Aortic Paraprosthetic-colonic Fistulae: A Review of the Literature

BACKGROUND

Aortic graft-colonic fistulae are a rare complication of aortic reconstructive surgery.

METHODS AND FINDINGS

A comprehensive review of this entity was performed based on the available literature from 1950 until 2006. Available reports were analyzed with respect to demographics, prior surgical intervention and its indication, prosthetic material used during the initial intervention, clinical presentation, the time interval in between the initial operation and symptoms, the method of treatment of the aortic graft-colonic fistula and its outcome.

The role of muscle flaps in wound salvage after vascular graft infections: the Emory experience

BACKGROUND

The incidence of prosthetic graft infection is 1 to 6 percent, and the mortality rate of infected aortoiliac or aortofemoral bypass is 25 to 75 percent. The goal of this study was to report the use of muscle flaps in the management of patients presenting with infected vascular grafts.

METHODS

A total of 22 patients required 26 muscle flaps to cover 24 infected vascular grafts. Muscle flaps were used for local wound control in all patients regardless of the fate of the graft. The vascular surgeons elected for graft salvage in eight of the 24 grafts. All of the muscle flaps survived.

RESULTS

The average time interval between the bypass and infection was 371 days. One-month follow-up revealed an 88 percent salvage rate, but this decreased to 50 percent during the mean follow-up of 23 months. None of the patients originally managed with a salvaged graft lost a limb, and overall, 14 of 22 limbs in this series remained viable (64.0 percent). The mortality rate during the index hospitalization was 9 percent. In this series, suprainguinal grafts had a higher mortality rate. In addition, infection occurring more than 1 month postoperatively, culture-positive Pseudomonas and methicillin-resistant species, and exposure of the arterial-graft anastomosis were poor prognostic indicators of graft preservation.

CONCLUSIONS

Management of infected vascular grafts remains a challenging problem. Muscle flap coverage should have a high priority, as the chance of a good outcome is highly favorable in early infections.

Infected pseudoaneurysm of the femoral artery secondary to melioidosis infection of a previous femoropopliteal bypass graft

Infected arterial aneurysm or pseudoaneurysm caused by Burkholderia pseudomallei is very rare; a review of the literature reveals only five previously reported cases. We report the first case of melioidosis infection of a previous femoropopliteal bypass graft complicated by para-anastomotic pseudoaneurysm of the femoral artery successfully treated by surgical removal of the old graft and creation of a new, extraanatomic, external iliac-to-popliteal bypass graft.

Primary aortoenteric fistula

BACKGROUND

A primary aortoenteric fistula (PAEF) is a rare clinical entity that results in fatal exsanguination if undiagnosed. The present study investigates whether management and survival have altered over time.

METHODS

A Medline search was conducted for the period from January 1994 to December 2003. Data were categorized and compared with reviews of PAEF published before this interval.

RESULTS

The classical triad (gastrointestinal bleeding, pain and a pulsating mass) was present in only 11 per cent of 81 patients. Most PAEFs were caused by an aneurysmal aorta and were almost always (94 per cent) heralded by repetitive gastrointestinal bleeds. Computed tomography (CT) provides images superior to those of other diagnostic modalities, such as gastroduodenoscopy or conventional angiography. Operative mortality rates were lower in later years possibly owing to improvements in perioperative care and the advent of endovascular techniques.

CONCLUSION

Gastrointestinal bleeding combined with a negative endoscopy in the presence of an aneurysmal aorta suggests PAEF and requires urgent evaluation by CT. Endovascular operation is an attractive treatment option.

Intra-abdominal aortic graft infection: complete or partial graft preservation in patients at very high risk

BACKGROUND

Total graft excision with in situ or extra-anatomic revascularization is considered mandatory to treat infection involving the body of aortic grafts. We present a series of nine patients with this complication and such severe comorbid medical illnesses or markedly hostile abdomens that traditional treatments were precluded. In these patients selective complete or partial graft preservation was used.

METHODS

Over the past 20 years we have treated nine infected infrarenal aortic prosthetic grafts with complete or partial graft preservation, because excision of the graft body was not feasible. In all nine patients infection of the main body of the aortic graft was documented at computed tomography or surgery. Essential adjuncts included percutaneous or operative drain placement into retroperitoneal abscess cavities and along the graft, with instillation of antibiotics three times daily, repeated debridement of infected groin wounds, and intravenous antibiotic therapy for at least 6 weeks.

RESULTS

One patient with purulent groin drainage treated with complete graft preservation died of sepsis. One patient with groin infection treated with complete graft preservation initially did well, but ultimately required total graft excision 5 months later, after clinical improvement. In four patients complete graft preservation was successful; two patients required excision of an occluded infected limb of the graft; and one patient underwent subtotal graft excision, leaving a graft remnant on the aorta, and axillopopliteal bypass. In summary, seven of nine patients survived hospitalization after complete or partial graft preservation; amputation was avoided in all but one patient; and no recurrent infection developed over mean follow-up of 7.6 years (range, 2-15 years).

CONCLUSIONS

Although contrary to conventional concepts, partial or complete graft preservation combined with aggressive drainage and groin wound debridement is an acceptable option for treatment of infection involving an entire aortic graft in selected patients with prohibitive risks for total graft excision. This treatment may be compatible with long-term survival and protracted absence of signs or symptoms of infection.

Prioritizing treatment in cases of concurrent abdominal aortic aneurysm

Patients with concomitant abdominal aortic aneurysm (AAA) and intra-abdominal malignancy present a clinical dilemma because of the difficulty in deciding which pathology to address first. As this scenario is not commonly encountered, clear guidelines are not available to help in the decision-making process. Surgery for malignancy has been said to increase the risk of postoperative aneurysm rupture, but simultaneous cancer surgery and primary repair of the aneurysm may carry the risk of prosthetic graft infection. This paper describes a further complication that may arise in the setting of concomitant intra-abdominal malignancy carcinoma and AAA, namely peripheral embolism.

Endovascular repair of bleeding aortoenteric fistulas: a 5-year experience

PURPOSE

Aortoenteric fistula (AEF) is an uncommon but catastrophic complication that can occur either primarily or after aortic reconstruction. Untreated, it is uniformly fatal. Conventional surgical management is associated with a perioperative mortality rate of 25% to 90% and frequent major complications. We reviewed our experience with the endovascular treatment of both primary and secondary AEFs in an effort to determine whether endovascular repair is a less morbid alternative to traditional surgical treatment in select patients.

METHODS

In a 5-year period, seven high-risk patients who had bleeding and an AEF documented by means of radiology or endoscopy (2 primary, 5 secondary) were treated with coil embolization (1) or placement of an endovascular aortic stent graft (3 aortouniiliac, 2 tube, 1 bifurcated). One patient underwent computed tomography (CT)-guided percutaneous catheter drainage of an infected perigraft collection. The average follow-up period was 27 months (range, 11-66 months), and follow-up consisted of physical examination, complete blood count, and contrast-enhanced helical CT scanning at 3, 6, and 12 months and yearly thereafter. All patients were treated with intravenous antibiotics perioperatively and were prescribed life-long oral antibiotics on discharge.

RESULTS

There was one perioperative death (14%) caused by fungal sepsis. Persistent sepsis after stent-graft placement necessitated laparotomy and bowel resection in one patient. One patient had three bouts of recurrent sepsis that were successfully treated with a change of antibiotic. There were three late deaths (43%) unrelated to the procedure or AEF. Three patients (43%) were alive and well an average of 36 months (range, 23-67 months) after the procedure, with no clinical or radiologic evidence of recurrent bleeding or infection.

CONCLUSION

Endovascular management of AEFs is technically feasible and may be the preferred treatment in select patients with bleeding and no signs of sepsis. In the setting of gross infection, it may also be considered in high-risk patients as a bridge to more definitive treatment after hemodynamic stabilization and optimization.

Value of bone scintiscan for diagnosis of arterial prosthesis infection: preliminary results

Diagnosis of arterial prosthetic infection is often difficult to confirm. Several cases of lower extremity hypertrophic osteoarthropathy (HOA) have been associated with arterial prosthetic infection. The presence of bone and joint abnormalities could constitute an early sign of HOA. The purpose of this prospective study was to determine the diagnostic value of routine bone scintiscan in patients hospitalized for suspected arterial prosthesis infection. Between December 1995 and May 1997, 17 patients with suspected infection were admitted to our institution. All underwent bone scintiscan before surgical treatment. Presence or absence of infection was defined according to the criteria proposed by Yeager. During the same period, bone scintiscan was performed in a control group of 8 patients with arterial prostheses but no clinical or laboratory signs of infection. Scintiscans were studied to detect bone and joint abnormalities distal to the arterial prosthesis. The results of this preliminary study indicate that routine bone scintiscan can assist definitive diagnosis in patients with suspected arterial prosthesis infection. Demonstration of bone and joint abnormalities distal to a prosthesis appears to be a fairly sensitive and highly specific sign of infection.

Surgical repair of infected peripheral graft and abdominal aortic aneurysm using arterial homograft

We report a case of combined surgical repair including lower limb revascularization (below-knee bypass) and abdominal aortic aneurysm repair using cryopreserved arterial homograft. The patient experienced lower limb ischemia due to repeated thrombosis of a long-infected polytetrafluoroethylene (PTFE) graft, and was also shown to have a complicating abdominal aortic aneurysm. Infection was eradicated with total graft excision and intravenous antibiotics. Two-year patency of the in situ arterial homograft revascularization was demonstrated with hemodynamic and tomographic controls; no degenerations have been found to date. Benefits of the use of in situ arterial homograft for arterial reconstruction may include improved hemodynamics and greater resistance to infection compared to when alloplastic materials are used. Because of the risk of allograft deterioration, close follow-up of the patient is required.

In situ replacement of infected aortic grafts with rifampicin-bonded prostheses: the Leicester experience (1992 to 1998)

PURPOSE

Prosthetic graft infection after aortic aneurysm surgery is a life-threatening complication. Treatment options include total graft excision and extra-anatomic bypass grafting or in situ replacement of the graft. The latter option is gaining increasing popularity, but the long-term outcome remains uncertain, particularly in light of the increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA). We performed a prospective nonrandomized study to assess the outcome after graft excision and in situ replacement with a rifampicin-bonded prosthesis for the treatment of major aortic graft infection.

METHODS

In a 6-year period from January 1992 to December 1997, 11 patients (eight men, three women) with major aortic graft infection underwent total graft excision and in situ replacement with a rifampicin-bonded prosthesis. The median age of the patients was 66 years (range, 49 to 78 years). Four patients had a hemorrhage from an aortoenteric fistula, three had a retroperitoneal abscess, two had graft occlusion, one had a perigraft collection shown by means of computed tomography, and one had a ruptured suprarenal false aneurysm. Organisms were cultured from 10 patients.

RESULTS

MRSA was isolated in two patients, both of whom had originally undergone repair of a ruptured abdominal aortic aneurysm. Two patients died (18.2%) within 30 days, and three patients (27.6%) had nonfatal complications (peritoneal candidiasis, transient renal impairment, and profound anorexia). Two patients died late in the follow-up period. Seven patients remain alive and clinically free of infection.

CONCLUSION

The long-term results after total graft excision and in situ replacement with a rifampicin-bonded prosthesis appear to be favorable. However, MRSA aortic graft infection appears to be associated with a poor prognosis.

Rabbit model for the study of aortic graft infection

Despite improvements in surgical technique and antimicrobial therapy, prosthetic aortic graft infections remain a challenging clinical problem. Diagnosis is difficult, and treatment results are less than optimal. An animal model is needed that will allow critical investigation of novel approaches in the therapy of aortic graft infections. Three-millimeter internal diameter polytetrafluoroethylene vascular prostheses were anastomosed as aortic interposition grafts in 25 rabbits. Increasing concentrations of Staphylococcus aureus (no bacteria to 1 x 10(8)) were applied topically to inserted grafts to initiate infection. There were 15 long-term survivors. Surviving rabbits were sacrificed at 2 weeks postoperatively to evaluate the development of aortic graft infection. Of the 15 survivors, 6 developed graft infection. All infected prosthetic aortas were innoculated with 1 x 10(4) or higher concentrations of S. aureus. A cost-effective, reliable model has been developed suitable for the study of prosthetic aortic infection.

False aneurysm of the axillary artery caused by graft infection: report of a case

A 77-year-old man presented to our hospital following the sudden onset of left subclavicular swelling, 8 years after undergoing subtotal removal of an axillofemoral bypass. Computed tomography revealed a rupture of the left axillary artery with the formation of a false aneurysm. Emergency surgery was performed in the form of an extraanatomic, axillo-axillary bypass with resection of the false aneurysm. Prior to removal of the false aneurysm, the subclavian artery was ligated via a left thoracotomy to minimize blood loss. The pathogen was identified as Proteus mirabilis, which is a rare causative organism for prosthetic graft infection. This case report demonstrates that total removal of the graft with revascularization should be performed for graft infections.

Comparison of endovascular and conventional vascular prostheses in an experimental infection model

INTRODUCTION

The causes and management of prosthetic graft infections have been extensively studied for conventional bypass grafts; however, the infectivity and therapy for endovascular graft infections are completely unknown. The aim of this study was to compare the biologic properties of infected aortic grafts when inserted by endoluminal or standard transabdominal techniques.

METHODS

Eighteen dogs underwent placement of polytetrafluoroethylene grafts in their infrarenal aortas either by an endovascular technique (8) or a standard interposition technique (10). Endovascular grafts were constructed from polytetrafluoroethylene (3 cm) and two balloon-expandable stents coaxially mounted onto a balloon catheter delivery system. The grafts were inserted through a left carotid arteriotomy under fluoroscopic control. Initially, seven grafts were infected with decreasing inocula of Staphylococcus aureus, starting at 10(7) organisms per ml for 30 minutes and then rinsed briefly (10 seconds) in normal saline solution, until a 50% infective dose for the standard grafts was determined to be 10(2) organisms per ml. After this initial experiment, a second group of 11 dogs were compared at a concentration of 10(2) S. aureus per ml. Five dogs underwent endovascular repair, and six dogs had standard graft interpositions after an identical period of bacterial exposure. All grafts were removed at 2 weeks under sterile conditions and were submitted for quantitative culture analysis.

RESULTS

Three of the six dogs (50%) with standard grafts appeared to clear their infections, whereas only one of the five dogs (20%) with an endovascular graft was free of organisms at 14 days. This results was further manifested by statistically significant lower postmortem colony counts in the standard grafts (p < 0.01).

CONCLUSIONS

The endoluminal position of the graft and its proximity to the arterial wall do not appear to provide protection against infection. These data suggest that if endovascular grafts become infected, they may be in a disadvantaged position for host defense mechanisms to be effective.

The surgical management of aortoenteric fistulas

Aortoenteric fistulas are serious and life-threatening complications of aortic surgery. Their exact pathogenesis is unknown, but mechanical erosion or infection leading to suture line failure are likely mechanisms. The presentation of an aortoenteric fistula can be seen months to years following the original operation, and clinical suspicion remains the cornerstone for diagnosis. When it is suspected, a prompt diagnostic work-up should be pursued in the absence of a readily recognizable source of hemorrhage. Once it is found, either by diagnostic studies or emergency laparotomy, repair can be accomplished by in situ graft replacement or extra-anatomic bypass with closure of the aortic stump. Thorough debridement of the aorta and perigraft tissues is essential for success and patient survival. As perioperative preparation and surgical techniques evolve, so too will the controversy concerning the optimal method for repair.

Management and outcome of infrapopliteal arterial graft infections with distal graft involvement

PURPOSE

The purpose of this study was to determine the outcome of patients with infrapopliteal artery graft infections (InfraPopGIs) who presented with graft infection distal to the popliteal artery.

PATIENTS AND METHODS

Between July 1, 1979 and June 30, 1994, 27 patients presented with infrapopliteal artery graft infections (18 polytetrafluoroethylene [PTFE], 9 autologous vein). The infection involved the anastomosis in 22 cases (8 anterior tibial, 8 posterior tibial, 4 peroneal, 2 dorsalis pedis arteries) and was localized to the body of the graft in 5 cases (4 calf, 1 ankle). All bypasses were originally performed for limb salvage. Twelve patients with patent grafts and intact anastomoses were managed by complete graft preservation. Fifteen patients presented with occluded grafts (10), anastomotic hemorrhage (4), or systemic sepsis (1) and were treated by total or subtotal graft excision.

RESULTS

The hospital mortality rate was 19% (5 of 27) and the amputation rate in survivors was 27% (6 of 22). These results were compared with a mortality rate of 13% (15 of 114; P > 0.05) and a limb loss rate of 10% (10 of 99)(P = 0.05) in 114 patients during this period who presented with infection proximal to the tibial arteries. Of 6 survivors with graft infections who required amputations, 5 lacked a suitable outflow artery for a secondary bypass and 1 developed progressive gangrene despite a patent secondary bypass. Among the other 16 survivors, 7 (44%) limbs remained viable without requiring a secondary bypass, 6 (37%) limbs were salvaged with successful preservation of patent grafts, and 3 (19%) required secondary bypasses to prevent limb loss.

CONCLUSIONS

Patients presenting with infrapopliteal artery graft infections have higher amputation rates than patients with more proximal infected peripheral grafts. Selective graft preservation and selective revascularization when outflow arteries are available are essential adjuncts to minimize high rates of limb loss associated in patients with graft infections.

Durability of cross-femoral grafts after aortic graft infection: the fate of autogenous conduits

PURPOSE

Revascularization for the treatment of aortic graft infection is usually accomplished by remote prosthetic axillofemoral bypass combined with cross-femoral bypass. When infection at the femoral level precludes placement of a prosthetic cross-femoral graft, we have used a variety of autogenous tissue conduits to restore circulation to the contralateral leg. To determine which of these conduits offers the most durable reconstruction, we have reviewed 78 patients treated for aortic graft infection.

METHODS

Between 1980 and 1991 we used either autogenous saphenous vein (ASV, n = 34), endarterectomized superficial femoral artery (SFA, n = 14), or direct ilioiliac anastomosis (iliac, n = 10) to provide cross-femoral flow. We compared the performance of these tissue conduits with a concurrent patient group with aortic graft infection in whom a prosthetic cross-femoral graft was used (prosthetic, n = 20).

RESULTS

Follow-up was available for 98.7% of patients, average 3.8 +/- 2.9 years, and was not different between the four groups. Bleeding complications occurred exclusively in the ASV group (n = 3, 8.8%) and were all in the perioperative period. In addition one ASV and one iliac conduit developed multiple false aneurysms. Hemodynamic conduit failure (thrombosis or stenosis) occurred in nine (26.5%) ASV conduits, six (42.8%) SFA conduits, and one iliac conduit, but not in the prosthetic group. When all of these adverse events were combined for each conduit group, both ASV and SFA conduits had a higher rate of conduit failure when compared with the prosthetic conduits (p < 0.05, log-rank test). Limb loss resulting from cross-femoral conduit failure occurred in six (17.6%) patients in the ASV group, four (28.6%) patients in the SFA group, and one patient each in the iliac and prosthetic groups. These differences were not significant.

CONCLUSIONS

We conclude that ASV and SFA conduits do not provide stable long-term cross-femoral revascularization and should be regarded as bridge grains until femoral infection is eradicated. When femoral infection mandates their use, frequent postoperative conduit surveillance is required. If ASV or SFA caliber is marginal, consideration should be given to the use of a larger autogenous conduit, such as superficial femoral vein.

Development of a Staphylococcus epidermidis vascular graft infection model in sheep

Staphylococcus epidermidis is an increasingly recognized causative organism of vascular graft infections. To increase our understanding of this problem we have tried to establish Staph. epidermidis vascular graft infection in sheep by direct inoculation. A 2 cm long, 5 mm diameter polytetrafluoroethylene (PTFE) or a gelatin sealed Dacron vascular graft was inserted into the left carotid artery. At the completion of the operation 1 mL of normal saline containing either 10(4), 10(6), or 10(8) colony forming units (cfu) of a slime producing Staph. epidermidis was inoculated directly onto the graft. After 3 weeks the grafts were harvested in a sterile fashion. Swabs were taken of the perigraft tissues and the external and internal aspects of the grafts; a 3-5 mm segment of the graft was incubated in broth medium and a second segment was ground for 5 min and then incubated in broth medium. Note was made of the presence of abscess formation, anastomotic failure or thrombosis. Thirteen sheep received a PTFE graft and 14 received a gelatin sealed Dacron graft. Three sheep died immediately postoperatively. The rate of infection was 40% at 10(4), 67% at 10(6) and 80% at 10(8) cfu Staph. epidermidis. In only four cases were all five cultures positive. In nine cases two or less cultures were positive, the majority of these being the broth cultures. Nine other organisms were isolated from nine mixed infections. Nine out of 13 PTFE and seven out of 11 Dacron grafts were infected.(ABSTRACT TRUNCATED AT 250 WORDS)

Secondary aortoenteric fistula: contemporary outcome with use of extraanatomic bypass and infected graft excision

PURPOSE

The standard treatment for secondary aortoenteric fistula (SAEF) has been infected graft removal (IGR) and extraanatomic bypass (EAB), an approach criticized for its high rate of death, amputation, and disruption of aortic closure. Recently, graft excision and in situ graft replacement has been proposed as a safer treatment alternative. Because the current outcome that can be achieved by use of the standard treatment of SAEF has really not been established, we reviewed the records of 33 patients treated for SAEF at our institution during a contemporary time interval (1980 to 1992).

METHODS

Thirteen patients (39.4%) were admitted with evidence of gastrointestinal bleeding and infection, whereas nine (27.3%) only had bleeding, 10 (30.3%) only had signs of infection, and one SAEF was entirely occult (graft thrombosis). Four patients required emergency operation. The fistula type was anastomotic in 13 (39.4%) patients, paraprosthetic in 15 (45.5%), and not specified in 4 cases. Thirty-two patients underwent EAB followed immediately by IGR (n = 16, 48.5%) or followed by IGR after a short interval, averaging 3.9 days (n = 16, 48.5%). The final patient underwent IGR, followed by EAB.

RESULTS

Follow-up on 31 patients (93.9%) averaged 4.4 +/- 3.7 years. There were nine deaths (27.3%) resulting from the SAEF, six perioperative and three late. Three patients (9.1%) had disrupted aortic closure. There were four amputations in three patients (9.1%), two perioperative and two late. Late EAB infection occurred in five patients (15.2%), leading to one death and one amputation. EAB failure occurred in six patients, two during operation and four late, leading to one amputation. The cumulative cure rate for this SAEF group was 70% at 3 years and thereafter. Compared with our earlier SAEF experience, this is a decline of 21% in the mortality rate, 19% in aortic disruption, and 27% in limb loss.

CONCLUSIONS

We conclude that outcome reports based on SAEF series extending over long time intervals do not accurately represent the results that are currently achieved with standard SAEF treatment with use of EAB plus IGR. This improved outcome is attributed to wide debridement of infected tissue beds, reduced intervals of lower body ischemia, and advances in perioperative management. To determine whether any new treatment approach actually offers improved outcome in the management of SAEF, comparison with EAB plus IGR should be limited to patients treated within the last decade at most.

Selective preservation of infected prosthetic arterial grafts. Analysis of a 20-year experience with 120 extracavitary-infected grafts

OBJECTIVE

The authors report on their 20-year experience with 120 patients with infected extracavitary prosthetic arterial grafts (95 polytetraflouroethylene, 25 Dacron). Throughout this experience, an effort was made, when appropriate, to salvage all or a portion of these infected grafts.

METHODS

When patients had arterial bleeding (20 cases) or systemic sepsis (6 cases), immediate graft excision was performed. When the infected graft was occluded (43 cases), subtotal graft excision was performed, leaving an oversewn 2- to 3-mm graft remnant to maintain patency of the artery. Complete graft preservation was attempted in 51 cases in which the graft was patent, the patient was not septic, and the anastomoses were intact. Aggressive operative wound debridement was repeated, as necessary, to achieve wound healing. The preferred method of revascularization, when necessary, included secondary bypasses tunneled through uninfected (often lateral) routes. Follow-up averaged 3 years (range, 1 month-20 years).

RESULTS

This strategy resulted in a hospital mortality of 12% (14/120) and a hospital amputation rate in survivors of 13% (14/106 threatened limbs). Of the surviving patients treated by complete graft preservation, the hospital amputation rate was only 4% (2/45) and long-term complete graft preservation was successful in 71% (32/45) of cases. Partial graft preservation also proved successful in 85% (35/41) of surviving patients who had occluded grafts. Successful complete graft preservation was as likely when gram-negative or gram-positive bacteria were cultured from the wound, with the exception of Pseudomonas (successful graft preservation in only 40% [4/10] of cases).

CONCLUSION

Based on this 20-year experience, the authors conclude that selective partial or complete graft preservation represents a simpler and better method of managing infected extracavitary prosthetic grafts than routine total graft excision.

Percutaneous transluminal angioplasty of the abdominal aorta

PURPOSE

To determine the long-term results of percutaneous transluminal angioplasty (PTA) of focal infrarenal abdominal aortic stenoses.

PATIENTS AND METHODS

Over a 10-year period, 15 focal infrarenal abdominal aortic stenoses were treated with PTA in 14 patients (13 women and one man; mean age, 53.2 years; range, 43-78 years).

RESULTS

The initial technical success rate was 100%. Clinical patency, as defined by continued absence or improvement in symptoms after PTA, was achieved in 14 of the 15 angioplasty procedures (93%) with a mean duration of clinical follow-up of 4.3 years (range, 0.6-9.8 years) in the 14 patients. Long-term noninvasive follow-up demonstrated continued patency of the angioplasty site in 11 of 11 patients available for study. The mean ankle-arm index in these 11 patients was 0.95 (range, 0.9-1.0) at a mean follow-up of 4.8 years (range, 0.6-9.8 years). There was no significant morbidity or mortality associated with the angioplasty procedures.

CONCLUSION

In view of the high degree of technical success and the excellent long-term patency, we believe that PTA should be considered a primary method of treatment in properly selected patients with focal abdominal aortic stenoses.

Antibiotic irrigation and conservative surgery for major aortic graft infection

PURPOSE

Traditional surgical treatment for panprosthetic aortic graft infection entails radical excision of the graft, aortic stump closure, and extraanatomic revascularization of the lower limbs. This carries an early mortality rate of 24% to 45%. Amputation rates range from 11% to 37%. Multiple operations and prolonged hospital stay are usual. We have developed a more conservative management technique with the aim of improving outcome.

METHODS

We describe an innovative method of treating the condition with prolonged, high-dose, local antibiotic irrigation therapy, systemic antibiotic treatment, surgical debridement, and graft conservation in a prospectively studied series of 10 patients.

RESULTS

The actual 30-day patient survival rate is 90%, the 1-year survival rate is 80%, and the 4-year survival rate is 67%. Two patients died because of graft infection, and the third died, uninfected, of an unrelated cause. No limbs have been amputated. Only two patients required a second operation. Mean postoperative hospital stay was 32 days. The seven survivors have been closely followed up with regular computed tomography or indium scanning and clinical examination and appear to be free from infection at a mean of 61 months after cessation of irrigation therapy.

CONCLUSION

The technique appears to represent a significant improvement in the management of this major complication of vascular surgery.

Infected abdominal aortic grafts

Aortic grafts were inserted in 1711 patients at Ottawa Civic Hospital (OCH) between 1976 and 1986. Aorto-iliac occlusive disease was the indication in 884 while in 827, the graft was inserted for abdominal aortic aneurysms. Graft infection occurred in 12 patients; six presenting with gastrointestinal bleeding due to aorto-enteric fistula (AEF) and the other six presenting with groin abscesses, mostly as a draining sinus. These were treated with graft excision and immediate extra-anatomic bypass. Seven patients died, giving a mortality rate of 58%. Three surviving patients required above-knee amputatio. These results are comparable to the results of others in the literature; therefore, continuing assessment of all aspects of graft infection and the search for more effective methods of prevention and management are needed.

Creation of a neo-aortoiliac system from lower extremity deep and superficial veins

OBJECTIVE

This study evaluated the morbidity, mortality, and intermediate term follow-up of patients undergoing replacement of their aortoiliac-femoral systems with lower extremity deep and superficial veins.

SUMMARY BACKGROUND DATA

The most commonly used treatment for aortic prosthetic infection is ectopic bypass and removal of the prosthesis. The overall mortality rate with this approach is approximately 20%, with an amputation rate of 10% to 14%. Other limitations include thrombosis of the ectopic bypass leading to limb loss, reinfection of the ectopic bypass, and aortic stump blowout. Dissatisfaction with this approach has led the authors to develop the following.

METHODS

A neo-aortoiliac system (NAIS) was fashioned from lower extremity deep veins (DV), greater saphenous veins (GSV), or both in patients with infected aortobifemoral prosthesis (n = 17) and other complex aortic problems (n = 3). Removal of infected prosthetic material, harvest of vein, and creation of NAIS was performed as a single-staged procedure.

RESULTS

The in-hospital mortality and amputation rates were 10% each. The mean (+/- standard deviation [SD]) operative time was 6.5 +/- 1.8 hours and the blood transfusion requirement was 4 +/- 3 units. Four patients experienced postoperative gastrointestinal complications with peritonitis and sepsis; NAIS vein graft resisted infection and remained intact. The mean follow-up time was 22.5 +/- 16 months. NAISs constructed from GSVs were prone to the development of focal stenoses requiring intervention or diffuse neointimal hyperplasia leading to occlusion. In contrast, all NAISs from larger caliber DVs have remained widely patent. The failure rate of GSV NAISs was 64%, compared to 0% for DV NAISs (p = 0.006). Despite the high failure rate in patients with GSV NAISs, none has required amputation. In patients who had DVs harvested for NAIS reconstruction, limb edema and other signs of venous hypertension have been minimal.

CONCLUSION

NAIS reconstruction from lower extremity veins is a successful option in patients with extensive aortic prosthetic infection and other complex aortic problems.

The role of computerized tomography in aorto-iliac vascular disease

Computerized tomography (CT) now has a definite place in the assessment of aortic vascular disease. In a study of 96 patients with abdominal or thoracic aorto-iliac problems, CT proved most useful in the management of haemodynamically stable patients with abdominal aortic aneurysms that were suspected of leaking. The complex anatomy associated with thoracic and abdominal aneurysms and aortic dissection was clearly defined. The interpretation of scans on postoperative aortic graft patients was difficult and less often helpful. The incidental finding of aortic disease during abdominal scans for a variety of other indications was infrequent and seldom contributed to patient management. The indications for CT have become far more selective.

Percutaneous transluminal aortic angioplasty: early and late results

Percutaneous transluminal angioplasty of the infrarenal abdominal aorta (13 patients) and its bifurcation (15 patients) was performed in 28 patients with a total of 32 dilatation procedures. The group consisted of 16 female and 12 male patients and initial successful dilatation was achieved in all. Recurrence within 1 month requiring bypass surgery occurred in 1 patient. Three patients were lost to follow-up. Long-term follow-up in the remaining 24 patients ranged from 1 to 9 years with a mean of 4.5 years. During the follow-up period, repeat angioplasty of the original stenosis was performed in 3 patients and another patient underwent dilatation of a new lesion which developed in the aorta. According to clinical and noninvasive studies, these 4 patients, as well as the other 20, have maintained patency of the treated lesions and are symptom free. No immediate complications requiring surgery occurred. We conclude that angioplasty is the initial treatment of choice in focal lesions of the distal abdominal aorta and its bifurcation.

[Possibilities for the use of 2nd generation cephalosporins in perioperative antibiotic prophylaxis]

Perioperative antibiotic prophylaxis has proven to prevent infections in a variety of surgical interventions such as colorectal, biliary and vascular surgery. The antimicrobial spectrum of an antibiotic used for perioperative prophylaxis should include Staphylococcus spp., Streptococcus spp. and Escherichia coli which are among the most frequent pathogens isolated from surgical infections. Second generation cephalosporins provide appropriate activity against these microorganisms. In colorectal surgery, combination with an anti-anaerobic agent is mandatory. During the past few years no major resistance development has been observed against second generation cephalosporins which are used at a dosage of 1.5 to 2 g. A single dose may provide sufficient serum levels for approximately three hours. Prolonged surgical procedures need an additional dose. Single dose prophylaxis with a second generation cephalosporin appears to be an appropriate strategy for infection prevention in surgery with regard to efficiency, safety and costs.

Axillobifemoral bypass and aortic exclusion for vascular septic lesions: a multicenter retrospective study of 98 cases. French University Association for Research in Surgery

Ninety-eight patients with aortic infection or aortoenteric fistula were treated by axillobifemoral bypasses and aortic exclusion by 22 surgical teams. Early mortality was 24%. Primary patency at two and five years was 62% and 55%, respectively. Actuarial primary patency at two and five years was 82% and 65%, respectively. The actuarial rate of limb salvage at two and five years was 90% and 82%, respectively. Eight aortic stumps ruptured in less than eight months, postoperatively. Two of these ruptures were treated with success. Infection of the axillobifemoral bypasses was observed in seven cases, six of which were treated successfully. Eight patients had axillary complications, all treated successfully without upper limb sequelae. In eight cases, the axillobifemoral bypass was replaced by a thoracic aortic bypass. Early mortality was higher after emergency operation (30%) than after elective operation (14%). Mortality after cure of primary infection (7%) was lower than after secondary infection (27%). The rate of infection in polytetrafluoroethylene axillobifemoral bypass (3%) was lower than in Dacron axillobifemoral bypass (13%). The rate of occlusion of polytetrafluoroethylene axillobifemoral bypass and Dacron axillobifemoral bypass was identical. The rate of occlusion in ringed reinforced grafts was lower (9%) than in the nonreinforced grafts (22%). The rate of occlusion was significantly higher after ablation of graft for occlusive lesions (38%) than after graft for aneurysms (7.9%) (p less than 0.01).

Ureteral injury in abdominal vascular reconstructive surgery

Iatrogenic ureteral injuries in vascular reconstructive surgery are rarely reported. We present a case of ureteral transection during repair of an aortic aneurysm in a patient with a previously placed aortobifemoral graft. In reported series of surgical ureteral injuries, 17 of 381 injuries occurred during vascular procedures. A review of the literature and management scheme for ureteral complications in the presence of prosthetic vascular grafts is presented in light of current endourologic materials and techniques.