Management of infected aortic prosthetic grafts

The management of infected prosthetic grafts is one of the most challenging problems facing vascular surgeons. High mortality and morbidity rates with traditional treatment have led many surgeons to consider different and novel strategies. Diagnosis is usually straightforward, but occasionally is unclear even after extensive clinical and radiologic investigations. Although routine total graft excision for all infected aortic grafts is still favored by some vascular surgeons, most favor only partial graft excision if only the distal limb of the graft is involved. Placement of in situ autologous vein or cryopreserved grafts have gained popularity, and investigations are continuing regarding the use of in situ antibiotic and silver-coated prosthetic grafts. In this article the authors review the incidence and etiology of aortic graft infections, methods to prevent these complications, the diagnosis of infected aortic grafts, and lastly the management of these complicated cases, including total graft excision and partial and complete graft preservation.     

Diagnosis and management of infected prosthetic aortic grafts

Infection of an aortic prosthetic graft represents one of the most difficult diagnostic and therapeutic challenges to the vascular surgeon. The presentation of this complication, the degree of ischemia of the lower extremities, and the overall medical status of the patient determine the urgency and optimal treatment to maximize limb salvage and survival. Although partial or total graft preservation can be a treatment option if the infection is localized to the distal limb of an aortofemoral graft and all anastomoses are intact, treatment of an infected aortic prosthetic graft often requires total graft excision, preferably preceded by revascularization of the lower extremities through lateral uninfected routes. Careful selection of the many time-honored and newly developed diagnostic and treatment modalities is necessary to lower morbidity and mortality rates in patients with this complication.     

Management of infected prosthetic dialysis arteriovenous grafts

BACKGROUND: Hemodialysis access is one of the most common vascular procedures that is performed by vascular and general surgeons. Prosthetic arteriovenous graft (AVG) infections pose potentially life-threatening septic and bleeding complications, as well as loss of dialysis access. Strategies employed to preserve some grafts, prevent morbidity in those with major infections, and maintain access are presented. METHODS: Between July 1, 1995 and August 1, 2002, 1441 AVG procedures were performed at a single institution. Fifty-one (3.5%) prosthetic AVG infections in 45 patients were identified. Twenty-seven graft infections occurred at a prior incision for placement or revision of a graft. The other 24 infections were located within the body of the graft, and 14 of these were documented to be at a recent puncture site for hemodialysis access. The most common presentation (47% [24/51]) was an exposed graft or a draining sinus tract. Management included total graft excision (TGE) when patients presented with sepsis or the entire graft was bathed in pus; subtotal graft excision (SGE), when all of the graft was removed except an oversewn small cuff of prosthetic material on an underlying patent artery; and partial graft excision (PGE), when only a limited infected portion of the graft was removed and a new graft was rerouted through adjacent sterile tissue to maintain patency of the original graft. RESULTS: None of the 45 patients died or developed hand ischemia. A uniformly successful outcome was achieved in all patients who were treated with TGE (13/13: 8 vein patches, 4 primary closure, 1 arterial ligation) or SGE (15/15). However, these treatments necessitated placement of a central venous catheter for temporary dialysis access and a new AVG later. All of these 28 wounds healed by secondary intention, including all 15 cases in which an oversewn cuff of prosthetic material remained. Graft patency and wound healing were achieved in 74% (17/23) of infections treated with PGE, and placement of a temporary dialysis access catheter and new AVG were avoided. The 6 failures of PGE ultimately required TGE because of nonhealing wounds, but there were no acute hemorrhagic or septic events. CONCLUSIONS: Systemic sepsis caused by prosthetic AVG infections mandates TGE. SGE and PGE can be safely employed in selected patients with infected prosthetic AVGs. SGE maintains patency of the underlying artery and avoids a difficult and time-consuming dissection. PGE offers the advantage of minimizing extensive dissection of well-incorporated uninfected graft segments and allows continued dialysis access at the incorporated portion of the graft.     

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.     

A systematic review of infected descending thoracic aortic grafts and endografts

ObjectiveThe objective of this study was to collect and critically analyze the current evidence on the modalities and results of treatment of descending thoracic aortic surgical graft (SG) and endograft (EG) infection, which represents a rare but dramatic complication after both surgical and endovascular aortic repair.MethodsA comprehensive electronic health database search (PubMed/MEDLINE, Scopus, Google Scholar, and the Cochrane Library) identified all articles that were published up to October 2017 reporting on thoracic aortic SG or EG infection. Observational studies, multicenter reports, single-center series and case reports, case-control studies, and guidelines were considered eligible if reporting specific results of treatment of descending thoracic aortic SG or EG infection. Comparisons of patients presenting with SG or EG infection and between invasive and conservative treatment were performed. Odds ratio (OR) meta-analyses were run when comparative data were available.ResultsForty-three studies reporting on 233 patients with infected SG (49) or EG (184) were included. Four were multicenter studies including 107 patients, all with EG infection, associated with a fistula in 91% of cases, with a reported overall survival at 2 years of 16% to 39%. The remaining 39 single-center studies included 49 patients with SG infection and 77 with EG infection. Association with aortoesophageal fistula was significantly more common with EG (60% vs 31%; P = .01). In addition, time interval from index procedure to infection was significantly shorter with EG (17 ± 21 months vs 32 ± 61 months; P = .03). Meta-analysis showed a trend of increased 1-year mortality in patients with SG infection compared with EG infection (pooled OR, 3.6; 95% confidence interval, 0.9-14.7; P = .073). Surgical management with infected graft explantation was associated with a trend toward lower 1-year mortality compared with graft preservation (pooled OR, 0.3; 95% confidence interval, 0.1-1.0; P = .056).ConclusionsThoracic aortic EG infection is likely to occur more frequently in association with aortoesophageal fistulas and in a shorter time compared with SG infection. Survival is poor in both groups, especially in patients with SG infection. Surgical treatment with graft explantation seems to be the preferable choice in fit patients.     

Prevention of paraplegia in transluminally placed endoluminal prosthetic grafts for descending thoracic aortic aneurysms.

OBJECTIVE: To evaluate the efficacy of a temporary balloon occlusion test for the prevention of paraplegia following transluminally placed endoluminal prosthetic grafts for descending thoracic aortic aneurysms. SUBJECTS AND METHODS: Two occlusion balloons were inserted via the brachial and femoral arteries and positioned in the proximal and distal neck of the descending thoracic aortic aneurysms using fluoroscopy. After temporary occlusion of the thoracic aorta by inflation of both the proximal and distal balloons, the evoked spinal potential was measured for 15 mins. A maximum amplitude during temporary balloon occlusion test decreasing by more than 20% of the pre-balloon occlusion level was considered to be significant, enough to not perform transluminally placed endoluminal prosthetic grafts, but instead an open repair. The test was applied in 12 cases (9 males and 3 females, 50-86 years old). All aneurysms were located between the Th6 and Th12 with a maximum diameter of 40-70 mm, and average of 56 mm. RESULTS: The changes in maximum amplitude of evoked spinal potential remained within 20% of the value before balloon occlusion in 11 cases. Transluminally placed endoluminal prosthetic grafts were performed in these 11 cases and no instance of paraplegia or other complication relating to the test was observed. Deployment of stent-grafts was successful in 10 cases (91%). CONCLUSION: It is suggested that the preoperative measurement of evoked spinal potential during temporary balloon occlusion is clinically useful for the assessment of the risk to paraplegia occurring in transluminally placed endoluminal prosthetic grafts.     

Cryopreserved aortic allograft replacement of infected prosthetic grafts in man: processing and clinical results

Abstract Aortic allografts preserved at °C have been used successfully for the replacement of infected prosthetic grafts, but have a limited storage duration and this does not allow for rigourous security of the allograft. Original cryopreservation protocol has been developed, characterized by the use of polyethylene glycol 20000 30 g/1 associated with 12.5% DMSO, high concentration of antibiotics (lincomycin 300 mg/1, vancomycin 125 mg/1), controlled freezing rate, and storage in the vapour phase of liquid nitrogen (- 150°C). Cryopreserved arterial allografts were used for the replacement of infected prostheses in 22 patients. In 2 patients, allograft-related dysfunction was observed, 3 patients died in the early postoperative period from non-allograft-related causes, and, 17 patients were cured of infection without any dysfunction of the allograft. These results are comparable to replacement by fresh allograft, but cryopreservation allows for better microbiological security, long-term storage, and, thus, better management of the available allografts.     

Cryopreserved aortic allograft replacement of infected prosthetic grafts in man: processing and clinical results

Aortic allografts preserved at 4 °C have been used successfully for the replacement of infected prosthetic grafts, but have a limited storage duration and this does not allow for rigourous security of the allograft. Original cryopreservation protocol has been developed, characterized by the use of polyethylene glycol 20 000 30 g/l associated with 12.5 % DMSO, high concentration of antibiotics (lincomycin 300 mg/l, vancomycin 125 mg/l), controlled freezing rate, and storage in the vapour phase of liquid nitrogen (? 150 °C). Cryopreserved arterial allografts were used for the replacement of infected prostheses in 22 patients. In 2 patients, allograft-related dysfunction was observed, 3 patients died in the early postoperative period from non-allograft-related causes, and, 17 patients were cured of infection without any dysfunction of the allograft. These results are comparable to replacement by fresh allograft, but cryopreservation allows for better microbiological security, long-term storage, and, thus, better management of the available allografts.     

Management of aortic prosthetic infections

Infections of aortic vascular prostheses remain a dreaded complication. Although removal of the graft has generally been recommended in the literature, the role of lesser procedures, the need for alternate revascularization, and a precise plan of attack are ill defined. We have treated 18 patients with infection of aortic prostheses. Specific risk factors potentially promoting infection included reoperation, septic complications, or gastrointestinal entry at the time of graft placement. Clinical signs of infection included chronic draining sinus in eight patients, localized groin abscess in three patients, groin swelling in four patients, gastrointestinal bleeding in two patients, and pseudoaneurysm in one patient. Treatment by local therapy, including catheter irrigation of sinus tracts, debridement, and local antibiotics, resulted in failure in eight of nine patients. If the sinogram of a groin sinus showed no communication with the body of the graft, resection of a graft limb was successful in 66 percent of the patients. If the sinus communicated with the body of the graft, total resection was mandatory. When total excision was necessary, all patients required revascularization by means of an extraanatomic bypass. The mortality rate was 33 percent and was primarily due to bleeding fistulas. An aggressive approach to this serious problem with early graft excision is encouraged.     

Platelet serotonin changes in dogs with prosthetic aortic grafts

The purpose of this study was to elucidate the mechanisms underlying the striking reduction in platelet serotonin found after placement of prosthetic aortic grafts in dogs. Changes in platelet serotonin paralleled changes in platelet survival time. Both were reduced after graft placement, remained depressed for up to a year, and then returned to normal. In vivo release of serotonin was assessed by labeling autologous platelets with ⁵¹Cr (a nonreleasable, cytoplasmic label) and ¹⁴C-serotonin (a releasable, storage granule label). In dogs with grafts, ¹⁴C-serotonin persisted in the circulation beyond the life span of ⁵¹Cr-labeled platelets. The ratio of platelet ¹⁴C/⁵¹Cr activity over 5 days following infusion of double-labeled platelets markedly increased. These data indicated in vivo release and reutilization of labeled serotonin. In vitro platelet uptake of ¹⁴C-serotonin was assessed in separate experiments and was found to be depressed following graft placement. We conclude that the reduction in platelet serotonin stems from platelet interaction with aortic prostheses. Platelets adhere to the prosthetic surface, release serotonin, and recirculate. Reutilization of released serotonin occurs but may be limited by depressed platelet uptake. The net effect is a reduction in platelet serotonin. These findings support our view that platelet interaction with prosthetic surfaces is, in large measure, a reversible phenomenon, with platelets reentering the circulation in an altered state.     

Laser-induced shock waves enhance sterilization of infected vascular prosthetic grafts

BACKGROUND AND OBJECTIVE: Bacteria that cause infection of vascular prosthetic grafts produce an exopolysaccharide matrix known as biofilm. Growth in biofilms protects the bacteria from leukocytes, antibodies and antimicrobial drugs. Laser-generated shock waves (SW) can disrupt biofilms and increase drug penetration. This study investigates the possibility of increasing antibiotic delivery and sterilization of vascular prosthetic graft. STUDY DESIGN/MATERIALS AND METHODS: Strains of Staphylococcus epidermidis and S. aureus were isolated from infected prosthetic grafts obtained directly from patients. Dacron grafts were inoculated with the isolated bacteria, which were allowed to form adherent bacterial colonies. The colonized grafts underwent the following treatments: (a) antibiotic (vancomycin) alone; (b) antibiotic and SW (c) saline only; and (d) saline and SW. Six hours after treatment, the grafts were sonicated, the effluent was cultured and the colony forming units (CFU) were counted. RESULTS: CFU recovered from control grafts colonized by S. epidermidis were comparable: saline, 3.05 x 10(8) and saline+SW 3.31 x 10(8). The number of S. epidermidis CFU diminished to 7.61 x 10(6) after antibiotic treatment but the combined antibiotic+SW treatment synergistically decreased CFU number to 1.27 x 10(4) (P<0.001). S. aureus showed a higher susceptibility to the antibiotic: 2.26 x 10(6) CFU; antibiotic +SW treatment also had an incremental effect: 8.27 x 10(4) CFU (P<0.001). CONCLUSIONS: This study demonstrates that laser-generated shock waves have no effects alone, but can enhance the effectiveness of antibiotics against bacteria associated with prosthetic vascular graft biofilms, suggesting that this treatment may be of value as adjunctive therapy for prosthetic graft infections.     

Late rupture of prosthetic aortic grafts. Presentation and management

Eight patients were treated for complications arising from actual holes in prosthetic aortofemoral or aortoiliac grafts. All occurred more than 8 years after implantation. Presentations varied and included shock from a graft-to-enteric fistula, a rapidly expanding painful femoral aneurysm, an acutely ischemic limb, and rest pain. The whole graft is suspect and must be assessed by aortography, but graft deterioration can be localized, which simplifies management. In our patients, holes in the body of the graft or near the bifurcation were approached transabdominally. We replaced as much of the graft as was reasonable under the circumstances. Two of the four patients died. Five patients had graft holes in the inguinal region which we believe were related to tethering in that area. For this reason, we recommend cutting the inguinal ligament and prosthetic limbs no more than 8 mm in diameter. Partial retroperitoneal resection with external sleeve support has been a durable alternative to a complete redo operation in patients with degeneration isolated to the inguinal area.