Popliteal Artery Aneurysm Repair Using a Covered Stent Graft Reinforced with Interwoven Nitinol Stent

VASCULAR DISEASE MANAGEMENT 2012;9(1):E3–E4

Abstract

Popliteal artery aneurysm (PAA) is the most commonly encountered peripheral arterial aneurysm in vascular medicine. Surgical correction has been the gold standard of therapy with endovascular techniques using covered stent grafts having comparable medium-term patency rates. However, despite being less invasive, this endovascular approach presents with problems such as stent thrombosis, endoleak, and recurrent ischemia necessitating reintervention. Herein, we present a new strategy paradigm in the percutaneous treatment of PAA using a covered stent graft superimposed with a high radial strength interwoven nitinol stent.

Introduction

Popliteal artery aneurysms (PAA) can result in acute limb ischemia due to thrombosis with distal embolization, or rarely, vessel rupture. Prompt recognition with effective therapy remains paramount in improving clinical outcomes. Traditional surgical treatment methods involve arterial bypass, preferably with an autologous vein, and ligation of the aneurysmal popliteal segment.¹ Although surgical outcomes are good, less invasive endovascular treatment with covered stent grafts have gained popularity due to lower morbidity and comparable patency rates.² However, complications associated with the percutaneous techniques, such as stent thrombosis and endoleak, have limited their widespread acceptance.

Case Report

A 64-year-old man was admitted for peripheral angiogram due to symptoms of bilateral lower extremity lifestyle-limiting claudication. Selective angiogram of the left lower extremity showed a heavily calcified mid to distal SFA with 80% diffuse, ulcerated stenoses, and a 2 cm PAA with 3-vessel runoff (Figure 1). Percutaneous intervention of the SFA was performed with Turbohawk directional atherectomy (ev3 Endovascular, Inc.) in the SFA followed by balloon angioplasty with good angiographic result. The PAA was then successfully excluded by deployment of a 7 x 150 mm Viabahn stent (Gore Medical), which was postdilated with a Sterling 7 x 100 mm balloon (Boston Scientific). A Supera 6 x 120 mm, self-expanding, high radial strength stent (IDEV Technologies Inc.) was then deployed within the Viabahn stent (Gore), covering the distal and proximal landing zones in order to reinforce the covered stent. There was a good angiographic result with brisk flow and preserved 3-vessel runoff (Figure 2).  The patient was discharged home the following morning and had no complications in 3 months of follow-up.   

Discussion

Popliteal artery aneurysm is the most commonly encountered peripheral arterial aneurysm in vascular medicine,³ and accounts for nearly 70% of all peripheral aneurysms.⁴ It is estimated that 10%-15% of patients with abdominal aortic aneurysm also have PAA. With 30% to 50% of patients being asymptomatic on presentation, prompt recognition and treatment are critically important.^5,6 Surgical repair by vessel ligation and arterial bypass has good results with 5-year patency rates >75%.⁷ Endovascular repair, in comparison, has similar medium-term patency rates, with a higher 30-day rate of stent thrombosis requiring reintervention, as demonstrated by a meta-analysis by Lovegrove et al² and corroborated by others.^7,8 In addition, endoleak is not uncommon, occurring in up to 20% of treated patients at 16-month follow-up.⁹  Covered stent graft use in the treatment of PAA functions by excluding the aneurysm, which decreases the axial force against the wall of the aneurysm, halting further growth and lowering the risk of rupture. Moreover, it prevents the formation of intraluminal thrombus and distal embolization.

The popliteal artery is a unique vessel under numerous mechanical forces, primarily flexion, as it spans the knee joint. Traditionally, peripheral interventionalists avoid stenting across a joint segment as the incidence of stent fracture and restenosis increase steeply. The radial strength of a Viabahn covered stent is inadequate for the amount of force exerted in the knee joint, and can often lead to kinking, bending, or even stent fracture (up to 16.7% in one prospective study).¹⁰ In addition, longitudinal movement of the stent, endoleak, or, as demonstrated in our case, stent thrombosis may occur. In a prospective study, by Tielliu et al, 24% of treated patients had stent thrombosis at 4-month mean follow-up.⁷ In an effort to avoid bending and thrombosis of stents, some interventionalists advise patients to avoid prolonged knee flexion greater than 90°. The Supera stent (IDEV) is a high radial strength stent composed of a wire interwoven nitinol design. The operator deploying the stent has the ability to adjust its radial strength by stacking the stent tighter over a desired area, thereby preventing kinking or fracture even across a flexion point. 

We have instituted a novel treatment of PAA by first excluding the aneurysm with a Viabahn covered stent (Gore), and then reinforcing and increasing the radial strength of the stent graft by deploying Supera stents (IDEV) within the Viabahn (Gore), covering both the proximal and distal edges across the joint. Our hypothesis is that a covered stent with higher radial strength may lead to improved outcomes in vessel patency, lower incidence of stent thrombosis, and therefore, reduced repeat intervention for limb ischemia. Further investigation with medium- and long-term follow-up will be required before wide acceptance of this treatment strategy for PAA.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr. George reports that he was paid an honoraria for consulting for IDEV Technologies. Drs. Varghese and Kovach report no potential conflicts.

Manuscript submitted November 15, 2011, provisional acceptance given November 22, 2011, final version accepted November 29, 2011.

Address for correspondence: Jon C. George, MD, Deborah Heart and Lung Center, Interventional Cardiology and Endovascular Medicine, 200 Trenton Road, Browns Mills, NJ 08015. E-mail: jcgeorgemd@hotmail.com

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