Arteriosclerotic Femoral Artery Aneurysms

Pathogenesis

The etiology of arteriosclerotic or degenerative femoral artery aneurysms is not clear. The multiplicity of aneurysms often found in patients with arteriosclerotic femoral artery aneurysms supports a systemic abnormality in the arterial wall or in the body's response to injury. Arterial wall damage can occur at locations where hemodynamic or mechanical factors cause arterial wall stress, such as proximal to major branching vessels or distal to a relative stenosis at the inguinal ligament. Similar to aortic aneurysms, an inflammatory infiltrate is seen in the wall of femoral aneurysms. In addition, hereditary factors affecting collagen or elastin production or stability and arterial wall enzyme activity can contribute to aneurysm formation. None of these factors satisfactorily explains the predilection of the disease for men; femoral aneurysms, like popliteal aneurysms, are much more common in men, with a male-to-female ratio of 20:1 or greater.

Pattern of Disease

Aneurysms of the proximal femoral arteries almost always involve the common femoral artery with or without involvement of the superficial femoral and profunda femoris arteries. Common femoral artery aneurysms can be categorized as type 1, being femoral artery aneurysms limited to the common femoral artery, or type 2, being those with involvement of the orifice of the profunda femoris artery. Type 1 and type 2 aneurysms occur with nearly equal frequency. The anatomic differences become important when planning arterial reconstruction. Type 2 aneurysms usually require a more complex procedure to ensure continued patency of both the superficial femoral and profunda femoris arteries.

Of great clinical significance is the common association of femoral artery aneurysms with life-threatening and limb-threatening aneurysms that can pose greater risk for the patient than the femoral aneurysm. In a series of 100 patients with arteriosclerotic femoral artery aneurysms seen at a single institution, aortoiliac aneurysms were detected in 85% of patients, thoracic aortic aneurysms in 6%, and popliteal aneurysms in 44%; 55% of the popliteal aneurysms were bilateral. In addition, 72% of patients had bilateral femoral artery aneurysms. Associated aortic aneurysms are more common in patients with bilateral femoral artery aneurysms.

Aneurysms of the proximal superficial femoral or profunda femoris artery without an ipsilateral common femoral artery aneurysm are unusual. Aneurysms of the profunda femoris artery often manifest with rupture. Asymptomatic proximal superficial femoral or profunda femoris artery aneurysms are being recognized more often with the increasing use of imaging modalities. Similar to common femoral artery aneurysms, concomitant aortic aneurysms are common.