Stent graft exclusion of a mycotic profunda femoris artery pseudoaneurysm with 2-year follow-up

Abstract

Mycotic pseudoaneurysms develop at sites of intimal disruption where bacterial invasion occurs. The conventional treatment involves arterial ligation, excision and debridement, followed by a bypass procedure at a later point. Recently, covered stent grafts have been used to treat mycotic arterial aneurysms either as temporary or definitive procedures. However, this is associated with a risk of stent graft infection, recurrence and rupture. There is a paucity of long-term results on the durability of such endovascular stent graft procedures in mycotic arterial pseudoaneurysms. We describe a successful endovascular covered stent repair of a mycotic profunda femoris artery pseudoaneurysm and follow-up of this repair at 2 years.

Background

A pseudoaneurysm is a contained rupture whose walls are formed by extravasated blood and the surrounding tissues. It is termed mycotic when its development results from arterial disruption by bacterial infection.¹ Mycotic profunda femoris artery (PFA) pseudoaneurysms are rare, and the treatment is generally decided on a case-by-case basis. The use of covered stent grafts to successfully exclude non-infected PFA pseudoaneurysms has been reported in the literature with good outcomes.^2–6

In the case of mycotic pseudoaneurysms, the use of stent grafts is avoided due to the risk of reinfection and open surgery is conventionally the preferred approach. However, open surgery has risks of morbidity such as bleeding, wound infection and prolonged hospital stay. In this report, we describe the successful exclusion of a mycotic PFA pseudoaneurysm with a covered stent graft and good outcomes on follow-up at 2 years.

Case presentation

A 54-year-old man presented with a 5-day history of ischaemic pain in his right foot. He had a background of ascending aortic aneurysm repair, aortic valve replacement and was taking warfarin. There was no history of intravenous drug use or lower limb trauma. The patient had a CT angiography (CTA) scan which showed a below knee popliteal occlusion. During his admission, he had an episode of unexplained fever; a transthoracic echocardiography scan was therefore requested and showed an infected thrombus overlying his metallic aortic valve. He was treated with intravenous antibiotics, and several blood cultures returned as negative. In addition, the patient had catheter-directed thrombolysis for acute right leg ischaemia and popliteal occlusion, which was unsuccessful. His symptoms of acute ischaemia worsened, and he developed sensory and motor deficits. He then underwent popliteal trifurcation embolectomy with an on-table angiogram and thrombolysis, but this also proved unsuccessful. An above-knee amputation was performed shortly afterwards, as the limb was no longer salvageable.

Investigations

The CTA scan completed on initial presentation also showed an incidental right-sided 1.8 cm partially thrombosed pseudoaneurysm from the first branch of the PFA (figure 1). A watch-and-wait approach was taken, and the patient was commenced on long-term intravenous antibiotic therapy guided by blood culture results. An arterial duplex scan was done 2 months later to monitor the PFA pseudoaneurysm which appeared to have significantly increased in size and had an irregular outline suggestive of contained rupture. The size had increased to 3.6 cm transverse diameter and 3.4 cm anterior–posterior diameter with virtually no neck (figure 2), and a new pulsating mass was palpable within his right thigh.

Figure 1.

Profunda femoris artery pseudoaneurysm at first detection.

Figure 2.

Catheter-directed CT angiography image of profunda femoris artery pseudoaneurysm at 2-month follow-up prior to treatment.

Treatment

A multidisciplinary team decision was made to treat the pseudoaneurysm with a covered stent graft. The rationale for this decision was to exclude the PFA pseudoaneurysm while maintaining perfusion of his above-knee stump through collateral arterial supply arising from the PFA. An 8×50 mm Viabahn stent was successfully planted in the proximal PFA, and there was no longer a palpable pulsating mass at the end of the procedure (figures 3 and 4). He was treated with intravenous antibiotics for a further 6 weeks postoperatively.

Figure 3.

Catheter-directed CT angiography image of the sealed pseudoaneurysm immediately after stent placement.

Figure 4.

Catheter-directed CT angiography image displaying stent graft after deployment.

Outcome and follow-up

The patient had three arterial duplex scans over the next 6 months and a further scan at 2 years, all of which demonstrated complete exclusion of the pseudoaneurysm (figure 5). Clinical examination at 2 years showed a healed above-knee stump, and no signs of infection or recurrence of the pseudoaneurysm. A subsequent duplex scan at 2 years showed that the stent graft had occluded but displayed no evidence of pseudoaneurysm recurrence.

Figure 5.

Arterial duplex image of stent graft at 6 months demonstrating patency of graft and pseudoaneurysm exclusion.

Discussion

In the treatment of this PFA pseudoaneurysm, there were a number of challenges that had to be taken into consideration. The depth of the PFA meant that ultrasound-guided compression, usually a first-line therapy, would very likely be unsuccessful. This patient had previous surgery to the groin, which would result in significant scarring making a surgical approach technically challenging. Furthermore, the presence of infection meant that revascularisation would have to be undertaken at a later time-point due to the risk of graft infection. Arterial infection is also a relative contraindication to embolisation and stent grafts due to the risk of bacterial colonisation of prosthetic material and reinfection. Furthermore, the lack of a pseudoaneurysm neck made thrombin injection and embolisation high risk for distal arterial embolisation. The multidisciplinary team consensus was therefore to offer a covered stent to exclude the pseudoaneurysm and maintain PFA flow to optimise healing of the above-knee stump.

On reviewing the available literature, we found that research into the management of mycotic pseudoaneurysms is sparse. There are three reports of mycotic PFA pseudoaneurysms; however, they were published before the advent of endovascular procedures.^7–9 There is one recent report on the successful use of embolisation to manage a ruptured mycotic PFA pseudoaneurysm, but no information on follow-up is provided.¹⁰ There are reports on the endovascular management of mycotic pseudoaneurysms arising from other peripheral arteries, either as a bridge to surgery or as a definitive treatment.^11–16 Notably, the longest follow-up seen among these cases was 18 months. Although in our case the stent graft had occluded at 2 years, it had served its purpose in treating the pseudoaneurysm, facilitating wound healing and allowing time for a collateral blood supply to form. This report therefore adds to this body of evidence indicating that stent graft repair may be a valuable treatment option. However, there is a real need for the reporting of long-term outcomes beyond 1 year and research comparing endovascular and open approaches in the treatment of mycotic pseudoaneurysms.

Learning points.

• In our experience, endovascular treatment with a covered stent graft for a mycotic profunda femoris artery pseudoaneurysm, and appropriate antibiotic therapy postprocedure for 6 weeks, was effective and durable with no recurrence at 2 years follow-up.

• Endovascular treatment with covered stent grafts and appropriate prolonged antibiotic therapy could be a useful adjunct, or alternative to open surgical repair, for peripheral arterial mycotic aneurysms.