Endovascular Treatment of Popliteal Artery Aneurysms

Popliteal artery aneurysms (PAAs) are rare, occurring usually in men older than 60 years. The incidence is significantly higher in patients with an abdominal aortic aneurysm (AAA), where up to 30% may be affected. These aneurysms have a tendency to occur bilaterally. PAAs exhibit symptoms in up to 70% of the cases within 5 years. Symptomatic PAAs can manifest with progressive intermittent claudication as a result of chronic peripheral embolization. In some cases this follows thrombosis of the PAA. Other cases manifest with severe ischemia of the limb as a consequence of acute thrombosis or embolization. In these patients, limb loss can follow if treatment is not immediately instituted. Both chronic and acute embolization make treatment tedious as the outflow vessels become less suitable for a bypass or interposition graft reconstruction. Elective treatment before symptoms occur is therefore indicated.

PAA growth rate per year is approximately 10% of its maximal diameter. The best timing for treatment of asymptomatic PAA with regard to the diameter is still the subject of continued debate. A PAA larger than 3 cm, especially with mural thrombus, is a clear indication for treatment. For a PAA between 2 and 3 cm in diameter there is no consensus.

Some advocate using a combination of aneurysm size and distortion of the popliteal artery as a guideline to treat asymptomatic PAAs. The highest predictive value for symptomatology is a diameter of at least 3 cm and a distortion of more than 45 degrees measured as the angle of the most proximal curve in the popliteal artery. It is unclear what the impact of thrombus is in the wall of the aneurysm on the occurrence of symptoms, although it is reasonable to recognize that thrombus can dislodge and cause peripheral embolization.

Indications for treatment and technical options have evolved across history. In the 18th and 19th centuries, indication was often rupture or symptomatic swelling of the limb. Compression or ligation was the only means to treat a symptomatic PAAs in those times. The 20th century was dominated by open arterial reconstructions with an interposition or bypass graft.

In 1994, the first report of endovascular repair of a PAA marked the beginning of a new era. Endovascular repair of a PAA involves introducing a covered stent at the level of the aneurysm, with landing zones both proximal and distal to the PAA in a healthy part of the popliteal or superficial femoral artery (SFA).