Volume 33, Issue 6 , Pages 684-686, June 2007
Peripheral Seeding of Mycotic Aneurysms from an Infected Aortic Stent Graft
Article Outline
Aortic stent graft infection is rare and there are no reported cases of seeded peripheral mycotic aneurysms complicating this condition. We describe the case of a 54 year old man who developed a late stent graft infection at three years, resulting in the peripheral seeding of three mycotic aneurysms with two incidents of rupture. He was successfully treated with extra-anatomic bypass of the aorta and both surgical and endovascular repair of his peripherally seeded mycotic aneurysms.
Keywords: Mycotic aneurysm, Aortic endograft, Aortic stent, Abdominal aortic aneurysm
Introduction
Mycotic aneurysms resulting from septic emboli are rare and usually occur following infective endocarditis. Septic emboli from infected aortic stents have been reported to cause splenic and colonic infarcts, but there are no reports of distal emboli forming peripheral mycotic aneurysms.
Case Report
A 54 year old man with bilateral short distance (50 yards) claudication, was found to have a tight distal aortic stenosis and an associated 3.5
cm saccular infra-renal aortic aneurysm. He was treated with a covered stent (Wallgraft®), but required a further bare metal stent (Palmaz®) to seal a proximal endoleak. Post-operatively his symptoms resolved and his aneurysm remained excluded on CT scans at 1, 2 and 3 years.
He re-presented at 3½ years with a three week history of back pain and seven days of rigors. He was septic with malaise and weight loss. His C-reactive protein was raised at 278mg/L and he had a leucocytosis of 13.6×109/L. CT demonstrated a contained endoleak with para-aortic inflammation and an intact stent. Laparotomy confirmed severe inflammation, friable tissues, but no infection. The stent was replaced with a Rifampicin soaked silver coated Dacron graft. Enterococcus faecalis sensitive to both amoxicillin and gentamicin was subsequently cultured from both the stent and its “pseudointima”, confirming the diagnosis of an infected stent graft. Despite appropriate antibiotic therapy, he remained septic, and within a week required a laparotomy for haemorrhage. His aortic graft was removed and replaced with bilateral axillo-femoral grafts.
Three weeks later he developed a right gluteal swelling. Ultrasound showed a large haematoma (16×6×10cm), which resolved with conservative management. Within days he developed tightness in his right calf, and an ultrasound, then CT, demonstrated a ruptured aneurysm of his posterior tibial artery (Fig. 1). The CT also revealed a small aneurysm of the left internal pudendal artery (Fig. 2.). The radiological diagnosis was that “these aneurysms are likely to be mycotic”. The posterior tibial aneurysm was excised and the artery ligated. The internal pudendal aneurysm was coil embolized. Histological examination of the posterior tibial aneurysm showed features consistent with the radiological diagnosis, although tissue was insufficient for microbiological confirmation. Echocardiography was normal, excluding infective endocarditis as an aetiology.
Fig. 1
CT reconstruction showing an aneurysm at the mid level of the posterior tibial artery.
Fig. 2
CT reconstruction showing the previously unknown small aneurysm in the left internal pudendal artery.
The patient has been maintained on long term co-trimoxazole and remains well at 18 months.
Discussion
The incidence of graft infection following aortic aneurysm repair is small. Fiorani et al.1 report a multicentre mean frequency rate of 0.4%. Of these 54.9% occurred more than 4 months post procedure with staphylococcus aureus and enterococcus pathogens accounting for the majority of infections (54.9% and 9.1% respectively). In our case the graft infection occurred at 3 years, with no preceding illness or additional invasive procedure. This highlights the lack of long term follow up data regarding the late infection rates of aortic stents, and the need for continued close follow up.
Whilst septic embolisation following aortic stenting2 and the development of peripheral mycotic aneurysms at the site of stenting3 have been described, the ‘seeding’ of peripheral mycotic aneurysms has only been reported following infective endocarditis.4 This case represents the first reported incidence of ‘seeding’ of peripheral mycotic aneurysm distal to an infected aortic stent. Whilst we have CT confirmation of two mycotic aneurysms, we have assumed that the contra-lateral buttock haematoma was the result of a further ruptured ‘seeded’ mycotic aneurysm.
Although rare, the incidence of aortic stent infections seems likely to rise. Treatment involves removal of the stent and replacement with an anatomic or extra-anatomic bypass. Several case reports have documented the use of superficial femoral veins5; this was not an option in this case due to the friability and intense inflammatory reaction encountered. Nevertheless, this experience emphasises the risks involved in the use of Dacron in an infected bed, despite appropriate antibiotic cover.
The management of disseminated peripheral mycotic aneurysms is unknown. Success has been reported with both endovascular and surgical strategies in combination with long term anti-biotics4 and this appears to have worked in our case.
In conclusion, we report a late aortic stent infection coupled with the distal ‘seeding’ of three mycotic aneurysms. With the increasing use of aortic stents, all clinicians should be aware of this potentially devastating and previously unreported complication.
References
- Endovascular graft infection: preliminary results of an international enquiry. J Endovasc Ther. 2003;10(5):919–927
- . Late infection of an endovascular stent graft with septic embolization, colonic perforation, and aortoduodenal fistula. Ann Vasc Surg. 2006;20(2):263–266
- Distal septic emboli and fatal brachiocephalic artery mycotic pseudoaneurysm as a complication of stenting. J Vasc Surg. 2002;36(3):625–628
- . Mycotic aneurysms affecting both lower legs of a patient with Candida endocarditis–endovascular therapy and open vascular surgery. Ann Vasc Surg. 2004;18(1):130–133
- . Excision and autogenous revascularization of an infected aortic stent graft resulting from a urinary tract infection. J Vasc Surg. 2002;36(3):622–624
PII: S1078-5884(07)00003-2
doi:10.1016/j.ejvs.2006.12.010
© 2007 Elsevier Ltd. All rights reserved.
Volume 33, Issue 6 , Pages 684-686, June 2007
