Complications of Endovascular Repair of Popliteal Artery Aneurysms

Introduction

Popliteal artery aneurysms (PAAs) occur at an incidence of 7.39 per 100,000 people, accounting for 80% of peripheral artery aneurysms. Typically asymptomatic, they are most commonly found incidentally on peripheral arterial disease screening examinations or when screening is based on the known presence of an aortic aneurysm, which confers a 12%–40% chance of popliteal artery aneurysm occurrence. PAAs may occasionally cause symptoms related to compression of surrounding structures (nerve palsy or leg swelling), but more frequently the symptoms are directly correlated with arterial occlusion in the form of emboli (i.e., blue toe syndrome) or acute limb ischemia from aneurysm thrombosis. Repair is recommended for PAAs ≥2 cm maximum diameter or when symptoms are present. Consideration should also be given to prophylactic repair for smaller aneurysms without symptoms when there is evidence of significant thrombus burden with prior embolization (poor run-off).

Traditionally, PAAs have been treated with open surgical techniques. Repair options include interposition reconstruction with excision of the aneurysmal segment or bypass with proximal and distal ligation of the aneurysm. Both medial and posterior approaches are well described, with the use of autologous vein preferred, but prosthetic conduits perform relatively well compared with its use in occlusive disease. Elective open surgical repair for PAAs is frequently reported, with greater than 80% cumulative patency at 3 years.

Despite the high patency rates for open repair, endovascular stent grafts provide an alternative to open PAA repair, with a greater number of patients undergoing endovascular repair than ever before. Early reports of endovascular PAA repair utilized the Wallgraft (Boston Scientific, Minneapolis, Minnesota), a self-expanding covered stent based on the Wallstent platform. At the time, it was the only available self-expanding covered stent, but it has limitations given its stainless steel base, which gives it limited flexibility and allows for a fair amount of lengthening and foreshortening depending upon the vessel diameter in which it is deployed. With the introduction of newer nitinol-based endoprosthesis, namely the Gore Viabahn (Gore Medical, Flagstaff, Arizona), came the potential of increased flexibility and easier deployment without the concerns of foreshortening, thus opening the door for more widespread use of the technique.

Endovascular repair of popliteal aneurysms has been reported with patency greater than 70% up to 4 years. Secondary interventions are most common for loss of patency, with in-stent stenosis resulting from kinking or in-folding of grafts. Additional reintervention may be required for extension of aneurysmal disease with subsequent endoleaks.

Evaluation for endovascular versus open repair of popliteal aneurysms is based on a variety of factors, including medical risk for anesthesia, baseline functional capacity, patient lifestyle, vascular anatomic characteristics, and acuity of presentation. In general, emergency repairs are a result of thrombotic events and thus are most frequently treated by open repair in our practice. This is not a mandate, of course, because catheter-directed therapies for management of acute thrombosis are being more frequently used and can allow more expeditious clot removal even for Rutherford IIb patients, but this has been our general experience to date. Patient concerns regarding recovery time from surgery may lead toward endovascular repair for highly functional patients needing to return to work quickly or to help care for loved ones. Similarly, older individuals and those with more medical comorbidities are more likely to be preferred for endovascular repair, but this will be balanced with objective evaluation of endovascular candidacy. Although a near infinite subjective discussion can be had regarding personal or patient preferences for when to perform open versus endovascular repair, a more appropriate first question concerns simple anatomic adequacy for repair, which will be discussed in greater detail later.