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Aneurysm, Femoral And Popliteal

Femoral and popliteal aneurysms result from progressive atherosclerotic changes occurring in the walls (medial layer) of the major peripheral arteries. Aneurysmal formations may be fusiform (spindle-shaped) or saccular (pouchlike), with fusiform occurring three times more frequently than saccular. They may be single or multiple segmental lesions, often company other arterial aneurysms located in the abdominal aorta or iliac arteries.

This condition occurs most frequently in men over age 50. The clinical course is usually progressive, eventually ending in thrombosis, embolization, and gangrene. Elective surgery before complications arise greatly improves the prognosis.

Causes

Femoral and popliteal aneurysms are usually secondary to atherosclerosis. Rarely, they result from congenital weakness in the arterial wall. They may also result from trauma (blunt or penetrating), bacterial infection, or peripheral vascular reconstructive surgery (which causes "suture line" aneurysms, whereby a blood clot forms a second lumen, also called false aneurysms).

Signs and symptoms

Popliteal aneurysms may cause pain in the popliteal space when they're large enough to compress the medial popliteal nerve and edema and venous distention if the vein is compressed. Femoral and popliteal aneurysms can produce symptoms of severe ischemia in the leg or foot, due to acute thrombosis within the aneurysmal sac, embolization of mural thrombus fragments and, rarely, rupture.

Diagnosis

In femoral aneurysm, the diagnosis is usually confirmed by bilateral palpation that reveals a pulsating mass above or below the inguinal ligament. When thrombosis has occurred, palpation detects a firm, nonpulsating mass.

Arteriography or ultrasonography may be indicated in doubtful situations. Arteriography may also detect associated aneurysms, especially those in the abdominal aorta and the iliac arteries. Ultrasonography may be helpful in determining the size of the popliteal or femoral aneurysm.

Treatment

Femoral and popliteal aneurysms require surgical bypass and reconstruction of the artery, usually with an autogenous saphenous vein graft replacement. Arterial occlusion that causes severe ischemia and gangrene may require leg amputation.

Special considerations

Before corrective surgery:

• Evaluate the patient's circulatory status, noting the location and quality of peripheral pulses in the affected arm or leg.
• Administer prophylactic antibiotics or anticoagulants as needed.
• Discuss expected postoperative procedures with the patient, and review the surgical procedure.

After arterial surgery:

• Monitor carefully for early signs of thrombosis or graft occlusion (loss of pulse, decreased skin temperature and sensation, severe pain) and infection (fever).
• Palpate distal pulses at least every hour for the first 24 hours, then as frequently as needed. Correlate these findings with preoperative circulatory assessment. Mark the sites on the patient's skin where pulses are palpable, to facilitate repeated checks.
• Help the patient walk soon after surgery, to prevent venostasis and possible thrombus formation.