CHICAGO—Using covered stents to treat pseudoaneurysms in arteriovenous (AV) grafts significantly increases the risk of graft infection, a study found.

“This is the first study to show this correlation, and should alert interventional radiologists, vascular surgeons, and nephrologists that we need to examine this issue more closely in order to come up with a solution,” said lead investigator Charles Kim, MD, Assistant Professor of Interventional Radiology at Duke University Medical Center in Durham, N.C.

“Nephrologists sometimes refer patients with large pseudoaneurysms to interventional radiologists to be treated with a covered stent because this method of treatment has been shown to be safe and effective.  However, based on the results of the study, I think we need to take a step back to figure out the optimal strategy for treating pseudoaneurysms.”

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Dr. Kim and his colleagues suspect that hematomas may be responsible for the increased infection risk. “Hematomas are highly susceptible to infection if they are contaminated with bacteria. Since these AV grafts are punctured with needles many times per week for hemodialysis, we have a potential culprit for the source of contamination,” Dr. Kim said.

He presented study findings at the Society of Interventional Radiology’s 2011 Annual Scientific Meeting.

Surgical revision has been the standard treatment for large pseudoaneurysms in AV grafts, Dr. Kim said. However, surgical revision carries with it increased morbidity compared with endovascular treatments, so potential alternatives should be considered. He and his colleagues examined whether covered stent use in polytetrafluoroethylene AV grafts impacts the incidence of subsequent infectious complications.

The researchers reviewed 258 interventions (in 190 patients) in which stents were used to treat pseudoaneurysms in AV grafts. Overall, 10.1% of the grafts were eventually excised because of infection, a rate that compares favorably to what is reported in the literature. However, when a covered stent was used, the incidence of graft infection was markedly higher at 41%. The median time from stenting until graft excision was 6.5 months.

Dr. Kim’s group also reviewed all of the surgeries on AV grafts excised because of infection over a 5.5-year period. Of 109 excisions, nearly a third of them were previously treated with a covered stent.

 “Given the marked morbidity associated with AV graft infections and subsequent excisions,” he told Renal & Urology News, “our data suggest that we need to come up with new strategies to minimize infection, such as decompression of the pseudoaneurysm at the time of covered stent deployment, antibiotic prophylaxis, or avoidance of this technique altogether.”