Most lower extremity aneurysms occur in men over age 50 years. Half are bilateral. One-third of patients with popliteal aneurysms and one-half of those with femoral aneurysms have an associated aortoiliac aneurysm.
Popliteal aneurysms account for approximately 85% of all peripheral artery aneurysms. Symptoms are rarely due to rupture but result rather from arterial thrombosis, peripheral embolization, or compression of adjacent structures with resultant venous thrombosis or neuropathy. Arterial thrombosis can be limb-threatening if all outflow vessels are occluded, leading to amputation in up to 30% of patients.
Ultrasound is the diagnostic study of choice to measure the diameter of the aneurysm as well as to search for other arterial aneurysms. MRA or conventional arteriography is required to define the anatomy of the outflow arteries in preparation for operative repair.
Surgery is recommended for all asymptomatic aneurysms larger than 2 cm and for all symptomatic aneurysms regardless of size. If preoperative angiography reveals no patent distal vessels for bypass, catheter-directed thrombolysis can be attempted. If a patent outflow vessel is identified or is recanalized with thrombolytic therapy, a saphenous vein bypass graft with proximal and distal ligation of the aneurysm is performed. In large aneurysms producing popliteal vein or nerve compression, resection of the aneurysm in addition to grafting is required.
Femoral aneurysms present as pulsatile groin masses. They have the potential for the same complications as popliteal aneurysms. Because the incidence of complications is lower than with popliteal aneurysms, patients with combined disease undergo repair of aortoiliac and popliteal aneurysms before repair of the femoral aneurysm.
Femoral pseudoaneurysms may result from injury produced by intravenous drug abuse, femoral artery puncture for angiography, or femoral line insertion. Mycotic aneurysms must be widely debrided with proximal and distal ligation or interposition grafting using autologous vein. Uninfected, small (> 5 cm) traumatic pseudoaneurysms can often be treated by ultrasound-guided compression of the neck of the aneurysm or by thrombin injection, which has a reported success rate of 90%. If these techniques are not successful, open repair is required. Pseudoaneurysms may also develop at the distal anastomosis of an aortofemoral bypass graft. They should be repaired if graft infection is suspected or if their diameter exceeds 2 cm.
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Revision date: July 3, 2011
Last revised: by Dave R. Roger, M.D.