Mycotic pseudoaneurysms due to injection drug use: a ten-year experience.

BACKGROUND: Arterial injury and infection due to repetitive injection drug use can result in mycotic pseudoaneurysm predisposing to hemorrhage, distal embolism, limb loss, and death. We hypothesized that debridement of the infected artery, followed by immediate vascular reconstruction, results in successful limb salvage in these patients.

METHODS: The setting was a county hospital. A retrospective review of all patients diagnosed with lower extremity pseudoaneurysms by the Departments of Surgery and Radiology between 2000 and 2009 was conducted. Outcome measures were patient characteristics, site(s) of lesion, type and results of imaging, type of operation, length of hospital stay, and complications.

RESULTS: Sixteen patients had 17 pseudoaneurysms. One of the patients had two mycotic pseudoaneurysms in the same region separated by a period of 10 months. Culture of the wall of the first pseudoaneurysm was not performed. The second pseudoaneurysm was culture positive. The 15 remaining mycotic pseudoaneurysms were all culture positive. Nine patients were men, and the median age of the patient group was 37 years. Common femoral pseudoaneurysms were the most frequent (76%). Symptoms included swelling (94%), pain (82%), and erythema (75.6%). A rapidly expanding pulsatile expansile mass was present in four of the patients. Computed tomography and percutaneous angiography were done in seven and four of the patients, respectively, and were diagnostic in all cases studied. Resection and reconstruction with autologous vein was the most common procedure (seven), followed by cadaveric grafting (four), synthetic grafting (two), ligation (two), and primary repair (two). Muscle flaps were used in 76.5% of the cases. Complications included anastomotic dehiscence (n = 3), acute thrombosis (n = 1), ischemia (n = 1), abscess (n = 1), and compartment syndrome (n = 1). Three of these patients required a second vascular reconstruction. One patient ultimately required an amputation. No postoperative deaths occurred. Methicillin-resistant Staphylococcus aureus was cultured from 13 of the 16 arterial walls.

CONCLUSION: Methicillin-resistant Staphylococcus aureus is the predominant organism causing mycotic aneurysms of the common and superficial femoral arteries owing to injection drug use at San Francisco General Hospital. Wide debridement of the infected artery and reconstruction with an in-line reversed saphenous vein or cryopreserved vascular allograft is a safe and effective method of treatment. Long-term follow-up studies are needed to determine the durability of this method of treatment.