Popliteal Artery Aneurysm

A popliteal artery with a diameter larger 7 mm is considered aneurysmal.

Aneurysms can be either true or false. True aneurysms are most commonly atherosclerotic, but can also be associated with connective tissue diseases, such as Marfan or Ehlers-Danlos syndromes, and with pregnancy. True popliteal aneurysms are the most common peripheral arterial aneurysms and are associated with aneurysms in other locations. An abdominal aortic aneurysm is seen in up to 50% of patients with popliteal artery aneurysms, and bilateral popliteal artery aneurysms are seen in up to 70% of cases. In contrast, popliteal artery aneurysms are present in ~15% of patients with abdominal aortic aneurysm. Therefore, patients with a popliteal artery aneurysm should be evaluated for an abdominal aortic aneurysm and for a contralateral popliteal artery aneurysm.

False aneurysms (pseudoaneurysms) can be caused by trauma or infection (mycotic aneurysm).

About 45% of patients with popliteal artery aneurysms are asymptomatic at the time of diagnosis. Symptomatic patients can present with lower-extremity ischemia, rest pain, or severe ischemia associated with thrombosis or embolization. Complications of untreated aneurysms are serious, with a high amputation rate with development of complications. Complications include thrombosis, distal embolization, and rupture (rare) and occur in up to 30% of aneurysms. For these reasons, it is recommended that patients with asymptomatic popliteal artery aneurysms undergo surgical repair, unless the patient is not a good surgical candidate.

Patients who present with acute thrombosis are treated with thrombolytic therapy to recanalize the distal popliteal and trifurcation vessels as targets for bypass surgery.

Diagnosis is most commonly made with ultrasound, which can help determine the patency of the aneurysm and whether the aneurysm contains thrombus. Color Doppler can differentiate an aneurysm from a popliteal mass such as a Baker cyst.

Conventional angiography may not not be helpful, especially if the artery is occluded. CTA and MRA can delineate the aneurysm sac and mural thrombus.

Case courtesy of Dr. Hansel Otero of Tufts Medical Center.

References

Wright LB, Matchett WJ, Cruz CP, James CA, Culp WC, Eidt JF, McCowan TC. Popliteal artery disease: diagnosis and treatment. Radiographics. 2004 Mar-Apr;24(2):467-79.