In situ revascularisation for femoropopliteal graft infection: ten years of experience with silver grafts

Introduction

Infection of synthetic vascular graft is rare but serious complication. It occurs in up to 6% ¹ and is associated with high mortality up to 50% and limb loss in 20% of cases. ²

The traditional treatment of synthetic graft infection consists of graft removal, debridement of all necrotic and infected surrounding tissue and extra-anatomic reconstruction. Since results, regarding aortic graft infection, were not promising with amputation rate up to 29%, aortic stump blowout in 20%, and graft reinfection in up to 40% of cases ³ it prompted number of investigators to use in situ revascularization as an option for treatment of aortic graft infection. ⁴ In recent years, Intervascular InterGard Silver (La Ciotat, France) graft impregnated with silver salts, as antimicrobial agent, entered clinical use. Promising results of its use in aortic position ⁵ led us to suppose that such grafts could be successfully used for peripheral graft infections. The purpose of this study was to analyze clinical outcome of patients treated with in situ reconstruction for femoropopliteal graft infection.

Methods

Total of 42 patients were treated in our hospital for femoropopliteal graft infection between December 2001 and December 2011. In 27 patients in situ implantation of silver graft was performed. These patients were enrolled in database formed in 2001 for prospective follow-up. Rest of the patients with infected and occluded grafts with irreversible ischemia and indication for amputation were excluded from the study. Also, patients with infragenual femoropopliteal grafts were excluded. All participants gave informed consent and study was approved by local Ethics Committee.

In the first half of decade, diagnosis was established by clinical examination and ultrasonography, and all patients underwent conventional angiography. In the second one, multislice computed tomography (MSCT) was added as a powerful tool for establishing diagnosis. In this period, conventional angiography was completely abandoned.

Whenever possible, specimens for microbiological culture were obtained prior to surgery, and adequate antibiotic therapy was initiated. In other cases, broad spectrum antibiotics were given prior to surgery and changed if necessary after obtaining intraoperative specimens.

Results

Total number of 27 patients was enrolled in study. Twenty (74%) patients were male and seven (26%) were female. Mean age was 65 years (range from 48 to 77 years). Nineteen (70%) patients were smokers, 14 (52%) had hypertension, 13 (48%) had dyslipidemia, 13 (48%) had diabetes, five (18%) had chronic obstructive pulmonary disease and five (18%) had chronic renal failure. Coronary artery disease was found in nine (33%) patients.

In majority (85%) of cases, initial synthetic graft placement was done because of occlusive disease. In 15% of cases it was done due to presence of aneurysmal disease.

Time between primary graft implantation and infection ranged from 1 to 13 months, average seven months.

The clinical presentation of graft infection is shown in Table 1.

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Table 1.

Clinical presentation of graft infection.

Clinical presentation	N	%
Cellulitis	2	7
Wound secretion	21	78
Graft exposure	1	4
Graft occlusion	3	11

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Table 2.

Microorganisms cultured from infected graft.

Microorganism	N	%
Staphylococcus aureus	16 a	59
Streptococcus	5	19
Enterobacter	4	15
Escherichia coli	2	7

N: number of patients; %: percent of patients.

a

Three patients with MRSA.

Preoperative cultures were obtained in 22 patients and in all patients intraoperative specimen was taken. Table 2 shows microorganisms cultured from infected graft.

In 14 patients infection was confined to the groin, in nine was confined to the region of distal anastomosis and in four patients involved entire graft length.

All surgical procedures were elective, except in three patients with acute graft occlusion and critical limb ischemia. The mean follow-up was 31 months (range from 1 to 60 months).

Early results – up to 30 days

In three patients, reinfection occurred in early postoperative period. In two of them groin in situ implantation of silver grafts was performed. Both of them developed reinfection in groin and died due to sepsis and multiple organ failure. In the third patient, in whom complete femoropopliteal graft was substituted with silver prosthesis, reinfection occurred involving total graft length. In this patient, major amputation was performed. All grafts were patent except in one case (abovementioned patient who underwent major amputation). These data are summarized in Table 3. The rest of patients had uneventful postoperative course, and mean duration of postoperative hospitalization was nine days (range from 7 to 11 days).

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Table 3.

Early results of in situ implantation of InterGard Silver grafts in treatment of vascular prosthesis infection.

N	%
Reinfection	3	11
Mortality	2	7
Amputation	1	4
Graft patency	26	96

N: number of patients; %: percent of patients.

Late results

Late reinfection occurred in two cases, after eight and ten months. In one patient major amputation was performed due to graft infection and occlusion and irreversible leg ischemia. In this patient, complete femoropopliteal graft was substituted with silver prosthesis eight months earlier. The other patient had partial infection of occluded graft without critical limb ischemia and partial removal of infected portion, confined to region of distal anastomosis, was performed. Ten months earlier, this patient underwent partial removal of infected graft in supragenual wound. Additional two patients with occluded grafts, but without evidence of infection, underwent major amputation due to foot gangrene. One patient died 36 months after surgery due to myocardial infarction. No pseudoaneurysm formation was noted. Data are summarized in Table 4.

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Table 4.

Late results of in situ implantation of InterGard Silver grafts in treatment of vascular prosthesis infection.

N	%
Reinfection	2	8
Mortality	1	4
Amputation	3	12
Graft patency	18	72

N: number of patients; %: percent of patients.

Overall survival and patency rate after 5 years follow-up were 82% and 42%, respectively (Figure 1). Non-reinfected primary patency rate was 81.8%. Limb salvage results are shown in Figure 2. OPEN IN VIEWER

Figure 1.

Kaplan-Meier estimates of survival and graft patency in patients treated by in situ implantation of InterGard Silver grafts for synthetic vascular prosthesis infection.

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Figure 2.

Life table reporting limb salvage.

Overall, reinfection occurred in five (18.5%) patients. Three patients had primary graft MRSA infection. All of them developed reinfection with same pathogen in early postoperative period, despite thorough wound debridement and silver graft implantation. These were the only patients with MRSA isolated from the wound. As previously mentioned, two of them died due to sepsis and multiple organ failure, and in one major amputation was performed. In two patients late reinfection developed and was caused by Streptococcus and their outcome is previously described.

Discussion

Reviewing the literature, the majority of papers regarding this topic are related to aortic graft infection. To our knowledge this is the first paper that deals with in situ implantation of silver grafts for femoropopliteal graft infection. This is the reason why our results cannot adequately be compared with those previously published.

When vascular graft infection occurs several options for treatment are available. Every approach has its own advantages and disadvantages. Since it is rarely seen, no large studies can be conducted and only limited number of patients is enrolled. Therefore no uniform recommendation for treatment can be advocated. Treatment of such devastating complication depends on clinical presentation, patient medical history, extent of infection and surgeon preference. Conventional treatment consists of excision of infected graft, necrotic tissue debridement and extra-anatomic reconstruction.^3,6 Conservative regimen, in some cases, could be an option. In situ implantation of various types of grafts is also described.^5,6,7–10

The primary endpoint of this study was recurrence of infection. Early reinfection occurred in 11% of patients, while late was present in 8% of cases. In all cases of early reinfection, causative microorganism was MRSA. This finding suggests that in cases of infection with virulent microorganisms, such as MRSA, in situ revascularization cannot be recommended and alternative therapeutic approaches should be considered. This observation is also suggested by Schmacht et al. ¹¹ Based on the results of this study, in cases of non-MRSA infection, in situ revascularization with silver grafts is reasonable option for graft infection treatment.

Previous experience with in situ implantation of InterGard Silver prosthesis^5,10 for aortic graft infection showed 6.5% and 3.7% of reinfection. Batt et al. ¹² reported 15.7% of late reinfection in aortic position. Oderich et al. ⁶ showed 11.5% of reinfection when rifampicin-bonded prostheses implanted in situ. Results from our study indicate higher rate of reinfection (18.5%) compared to previously cited reports.

Autogenous veins and cryopreserved allografts are associated with the lowest rates of reinfection, 2.4% and 0.7%, respectively.^7,8 However, in some cases autogenous vein may be previously harvested for aortocoronary bypass procedures or may not be suitable for use due to small diameter or varicose syndrome. For cryopreserved grafts principal limitation is the expense.

Antibiotic therapy was administered during hospital stay and maximum one month after the discharge while others reported such therapy for several months and even life-long suppressive doses.^6,10 In our study, vancomycin was used to treat patients with MRSA infection.

In this study perioperative mortality was 7% (2 of 27 patients). Both patients died due to graft reinfection with MRSA and cause of death was multiple organ failure due to persistent infection. Major amputation was done in one (4%) patient and graft patency in first 30 days was 96%. Batt et al. ⁵ and Zegelman and Gunther ¹⁰ reported perioperative mortality of 16.6% and 6.5%, respectively, with no amputation reported.

Oderich et al. ⁶ and Bandyk et al. ⁹ reported no amputation rate during follow-up, while we observed three major amputations, in two patients due to foot gangrene and in one due to graft reinfection. We found no pseudoaneurysm formation and one death not related to previously performed procedure.

With progress in field of vascular surgery and critical care, treatment of vascular graft infection also changes. O’Connor et al. ¹³ in their meta-analysis challenged the status of extra-anatomic bypass as the gold standard for treatment of aortic graft infection. They showed statistically significant difference in favour of patients treated by in situ reconstruction with autogenous veins, rifampicin-bonded prosthesis and cryopreserved allografts versus extra-anatomic bypass.

Treatment of prosthetic graft infection should be individually tailored for each patient. In situ implantation of silver grafts is one of the options. They are readily available from shelf (not in United Sates). Also, in situ revascularization is easier to perform than extra-anatomic bypass.

Results regarding its clinical use presented in this study are according to our opinion acceptable. However, risk of reinfection remains as with other treatment modalities.