Cryopreserved saphenous vein allograft for infragenicular bypass in the presence of foot infection

Introduction

Autogenous greater saphenous vein is the bypass conduit of choice for infrainguinal reconstruction. In the presence of infection when autogenous vein is unavailable due to multiple previous operations having exhausted the supply, the risk of major limb loss or death is high.^1–3 Cryopreserved saphenous vein allograft (CSVA) yields satisfactory patency and limb salvage rates when no autogenous vein is available.^4–8 This report describes our recent experience with the use of CSVA for salvage of the limb in the setting of infection.

Materials and methods

Between July 2004 and May 2010, 12 patients with overt foot infections underwent 13 arterial reconstructions with CSVA. The mean age was 68.4 ± 2.2 years (range 56–80 years). Associated comorbidities included hypertension (100%), diabetes mellitus (54%), coronary artery disease (39%), cigarette smoking (62%) and end stage renal disease (23%). The indication for operation was limb salvage in all patients and all patients were designated as Rutherford Class 5 and 6. ⁹

Cryopreserved human allografts offer the patient an alternative to amputation in these ‘last resort’ settings and have undergone a number of modifications over the years. The allografts are aseptically recovered from qualified donors by recovery organizations and regional tissue banks, within 24 hours of asystole, and sent with consent to CryoLife, Inc. (Kennesaw, GA, USA). The allograft is dissected free from the surrounding tissue, inspected for attributes and irreparable defects are dissected away. The allograft is then incubated in a tissue culture medium containing a mixture of antimicrobials. The allograft is cryopreserved in a tissue culture medium containing cryoprotectants within the CryoSafe® packaging system's innermost pouch of a three-pouch packaging system. The packaging system not only withstands ultracold temperatures, but also allows for aseptic introduction of the allograft into the operating environment. Supercooling by liquid nitrogen boost is begun prior to crystallization to minimize ice crystal damage to the allograft matrix. Finally, the allograft is transferred for long-term storage at or below −135℃. All CryoVein® cryopreserved human saphenous vein allografts were obtained from CryoLife®, Inc. and were prepared following the manufacturer's instructions.

Wide debridement and copious irrigation was performed on all infected tissue beds. All patients were donor matched to recipient blood groups. All patients were administered perioperative broad-spectrum antibiotics until specific organism cultures were available. Postoperative anticoagulation was not used; all patients received antiplatelet agents.

Results

Twelve patients underwent 13 infrainguinal bypasses with CSVA. Two patients died with open grafts during follow-up at nine (multi-system organ failure) and 52 days (homicide) postoperatively which corresponds to an 83% survival rate during follow-up. Three grafts failed during follow-up between one and 36.3 months (mean 11.7 ± 3.3 months). Two of these patients underwent amputation for an 82% limb salvage rate (Figure 1); the third patient was being followed in the wound clinic, but the prognosis was poor. The primary cumulative patency rate as determined by Kaplan–Meier analysis is 40% (±20%) and the primary assisted patency 60% (±19%) at 18 months follow-up (Figure 1). To obtain this primary assisted patency rate on failing grafts, one patient underwent PTA/stent angioplasty and one patch angioplasty. OPEN IN VIEWER

Discussion

Arterial reconstruction in the presence of lower extremity infection remains among the most challenging problems in vascular surgery, with amputation rates approaching 40%. ¹⁰ In the infected field, autogenous tissue is the best conduit for arterial reconstruction, but autografts are not always available, especially in ‘arteriopath’ patients who have had multiple previous lower extremity operations. As previously reported, ¹¹ ABO-blood group are matched between donor and recipient, although potential clinical impact is difficult to ascertain due to the small patient numbers.

The aim of this study was to evaluate the role of cryopreserved human allograft for limb salvage arterial reconstruction in the setting of infection. An allograft conduit which is resistant to infection, readily available and can be placed in an expedient manner in these ‘high risk’ limb salvage patients is attractive. In this high risk, complex patient population, there were two perioperative deaths. Donker ¹² recently reported two-year primary and primary assisted patency of 34 and 36%, respectively, with polytetrafluoroethylene pre-cuffed bypass grafts in the infragenicular location with a corresponding 59% limb salvage rate. Relative to these outcomes, our 40% primary patency and 60% primary assisted patency at 18 months follow-up attained an 82% limb salvage rate. Of note, among the three patients whose grafts failed, two had both diabetes and chronic renal failure. In this subset of inordinate high risk limb loss patients, primary amputation may be warranted, but a larger sample size is needed to make this judgement. Clearly the CVSA, while patent, helped heal the infected wounds with comparable outcomes to other previously reported allograft series. ¹¹ In this difficult, complex patient population, CSVA appears to be a reasonable alternative to a major limb amputation. Larger patient populations and longer follow-up are needed to determine if this arterial reconstruction with CSVA is safe and durable enough to salvage limbs in the presence of infection. The continued use of CSVA in this setting appears warranted.