Cath Lab Digest

Introduction
Pseudo-aneurysm formation after vascular reconstruction is a rarely encountered problem in the treatment of peripheral arterial disease (PAD). It has most commonly been described in the vascular surgical literature as a delayed complication of lower extremity bypass surgery, and the usual mode of repair has been surgical. Recent advances in minimally invasive therapy for this clinical entity have centered on ultrasound-guided compression and thrombin injection to obliterate the cavity and restore vascular integrity. With the advent of stent-supported angioplasty, endovascular methods of treatment for iatrogenic pseudoaneurysms have generated renewed interest. The following case outlines the rare occurrence of, and therapy for, a delayed non-anastomotic pseudo-aneurysm caused by balloon angioplasty and self-expanding stent deployment in a previously occluded venous femoral-popliteal bypass graft.

Case Report
A 73-year-old female with diabetes, hypertension and hypercholesterolemia presented to our center with rest pain of the right foot. She had a history of chronic PAD, and had previously undergone left above-knee femoral-popliteal bypass grafting, followed by above-knee right femoral-popliteal bypass grafting using saphenous vein for progressive bilateral lower extremity claudication. The right femoral-popliteal bypass graft was nine months old. Resting ankle-brachial indices were 0.40 on the right and 1.1 on the left. Angiography revealed a totally occluded vein graft in its proximal segment (Figure 1). She then underwent successful recanalization of the graft with balloon angioplasty with a 5 x 60 mm balloon catheter, after an overnight course of catheter-directed lytic therapy with tissue plasminogen activator failed to recanalize the occluded graft. Self-expanding 6 mm diameter nitinol stents were placed at the proximal and distal graft anastomosis to treat severe diffuse residual disease after balloon angioplasty with a satisfactory final angiographic result (Figure 2).

She presented 3 days after this procedure with the acute onset of severe, tearing right thigh pain radiating to the calf. On exam her right thigh was enlarged, tense, warm and diffusely tender to gentle palpation. She had palpable femoral pulses and her popliteal, dorsalis pedis and posterior tibial pulses were brisk and easily visible by Doppler. Arterial Doppler of lower extremities revealed ankle-brachial indices of .54 on the right and 1.01 on the left, essentially unchanged from her post-angioplasty baseline. Emergent CT angiography (Figure 3) revealed a 3 cm x 6 cm pseudoaneurysm from rupture of the right femoral popliteal saphenous bypass graft just cephalad to the self-expanding nitinol stent placed in the distal graft.

Retrograde contralateral access was obtained in the left common femoral artery and a 5 Fr catheter was positioned in the graft. Arteriography confirmed rupture of the mid segment of the saphenous vein graft and a large pseudoaneurysm in the mid right thigh (Figure 4). The stents in the proximal and distal graft were patent and there was 1 vessel run-off to the foot (Figure 5).

An 0.035” Amplatz Super Stiff™ guidewire (Boston Scientific, Fremont, California) was positioned in the distal graft and a 10 Fr Arrow sheath was positioned in the proximal left common iliac artery. The sheath would not cross over the rather steep aortic bifurcation. Utilizing a “buddy wire” technique with the Amplatz wire and a STORQ soft wire (Cordis Corp, Miami, Florida) positioned in the right common femoral artery, a 7 mm x 5 cm GORE Viabahn stent graft was positioned in the mid segment of the right femoral popliteal bypass graft at the site of the rupture. The stent graft was deployed without incident, with complete coverage of the rupture site. A 5 mm x 40 mm balloon was positioned within the stented segment and two inflations performed to appose the stent graft at nominal pressures. Final angiography revealed complete apposition of the stent with sealing of the leak (Figure 6). Distal popliteal arteriography and infra-popliteal run-off angiography revealed preserved single vessel runoff to the foot. The patient was discharged on a regimen of aspirin and clopidogrel, with resolution of her symptoms. Follow up ankle brachial indices two weeks post procedure were .58 on the right and .95 on the left, demonstrating improvement. Repeat CT angiography performed two weeks post procedure revealed continued integrity and patency of the bypass graft (Figure 7).

Pseudoaneurysm (PA) formation after vascular surgical reconstruction is most commonly associated with disruption of an arterial anastomosis after either aortofemoral bypass or infrainguinal bypass, or as a complication of dialysis graft fistulas.⁷ The cumulative risk of clinically significant PA’s after surgery remains small between 2–6%.⁷ The incidence of false aneurysm formation after balloon angioplasty is also rare; only a few case reports describing the clinical phenomenon exist.^4–6,9,19 Palmaz et al reported two cases of PA formation in a review of the initial multicenter experience with iliac stenting, suggesting that stents may contribute significantly to the risk of PA formation.²⁰ Pseudoaneurysms can, if left untreated, be complicated by thrombosis, rupture or distal embolization. Active hemorrhage with continuing expansion, severe unremitting pain and impending compartment syndrome are among the indications for urgent surgical intervention. Early surgical repair is usually mandated in these cases, with interposition graft placement being the procedure of choice.⁷