Explain the presentation, diagnostic workup, and operative plan for emergent femoral artery embolectomy in acute femoral occlusion.

Acute Femoral Artery Occlusion: Presentation, Workup, and Operative Plan

Clinical Presentation

Acute femoral artery occlusion classically presents with the "6 P's": pain, paralysis, paresthesia, pulselessness, pallor, and poikilothermia (coolness), though painless presentations with isolated neurologic deficits can occur. 1

Key Presenting Features

• Sudden onset of severe leg pain radiating distally, typically occurring within hours 2, 3
• Absent femoral pulse on the affected side, with potential bilateral involvement 1
• Motor and sensory deficits ranging from paresthesias to complete paralysis and anesthesia 1
• Muscle tenderness indicating compartment syndrome risk 2
• Contralateral palpable popliteal pulse may be a critical diagnostic clue suggesting underlying popliteal aneurysm thrombosis rather than simple embolism 4

Critical Distinction: Embolism vs. Thrombosis

• Embolic occlusion: Sudden onset, identifiable cardiac source (atrial fibrillation in 78% of cases), most commonly lodges at the common femoral bifurcation 2, 5
• Thrombotic occlusion: Preceded by progressive claudication, occurs most commonly in the superficial femoral artery with underlying atherosclerotic disease, less abrupt onset 5
• Popliteal aneurysm thrombosis: Commonly mistaken for embolic event, diagnosis often made intraoperatively during attempted embolectomy 4

Diagnostic Workup

Immediate Bedside Assessment

• Assess limb viability immediately using the 5 P's (pain, paralysis, paresthesias, pulselessness, pallor) to determine urgency 6
• Initiate systemic anticoagulation with heparin immediately to prevent proximal and distal thrombus propagation, regardless of planned intervention 6, 5
• Document ischemia duration from symptom onset, as duration >24 hours significantly worsens limb salvage outcomes 2

Point-of-Care Ultrasound

Bedside ultrasound performed by the emergency physician or vascular specialist can rapidly localize the occlusion and guide immediate management without delaying definitive therapy. 4, 3

• B-mode findings: Echogenic material within the artery, noncompressible vessel 3
• Doppler findings: Absent flow signal at the occlusion site 3
• Evaluate bilateral common femoral arteries to assess for bilateral disease or contralateral popliteal aneurysm 4
• Brief venous examination excludes phlegmasia cerulea dolens as alternative diagnosis 4

Advanced Imaging (When Time Permits)

• CT angiography is fast and reveals the exact nature, level of thrombosis, and underlying atherosclerotic disease 4
• Ultrasound imaging is the most rapid means to confirm popliteal aneurysm when suspected 4
• Catheter angiography provides detailed anatomic information and allows catheter-based treatment in viable or marginally threatened limbs (Rutherford class I or IIa) 4

Critical Caveat on Imaging

Patients with severe ischemia indicated by motor loss or severe sensory deficits (Rutherford class IIb or III) should proceed directly to definitive therapy without imaging studies that would delay treatment. 4

Operative Plan for Emergent Femoral Embolectomy

Indications for Immediate Surgery

• Immediately threatened limbs (Rutherford class IIb and early class III) require emergency thromboembolectomy within hours to prevent limb loss 4, 6
• Ischemic myositis (muscle tenderness) is the best clinical predictor of nonviability and indicates need for urgent intervention 5
• Ischemia duration <24 hours with viable limb offers best outcomes for embolectomy 2

Surgical Technique

All patients should undergo lower limb embolectomy using the Fogarty catheter, with femoral artery access in 70.9% of cases. 2

• Primary approach: Common femoral artery exposure and Fogarty catheter thrombectomy 2, 5
• Assess for underlying lesions: If thrombosis rather than embolism is discovered intraoperatively, address the underlying atherosclerotic lesion 4, 5
• Perform fasciotomy in patients with compartment syndrome (required in approximately 30% of cases) 2
• Evaluate distal runoff: If absent runoff vessels are identified, consider catheter-directed thrombolysis or mechanical thrombectomy to restore distal flow and resolve emboli 4, 6

Alternative Endovascular Approach

Catheter-directed thrombolysis is recommended for viable limbs when a guidewire can be passed across the lesion, with one-year limb salvage rates similar to surgery but lower mortality and higher recurrent ischemia rates. 6

• Mechanical thrombectomy with the Amplatz device achieves 78% complete recanalization of the deep femoral artery with 94% limb salvage at 9 months 7
• Additional aspiration thrombectomy of tibial arteries may be required in 50% of cases 7
• Supplemental local thrombolysis with urokinase needed in approximately 67% of mechanical thrombectomy cases 7

Prognostic Factors

• Limb preservation is significantly higher in patients without muscle tenderness, with normal motor activity, and ischemia duration <24 hours 2
• Immediate postoperative mortality is 13.5%, with 68.4% due to cardiac causes 2
• Amputation rate among survivors is 16.4% due to persistent arterial occlusion 2
• Repeat embolectomy required in 7.3% of cases 7

Critical Pitfalls to Avoid

• Do not delay revascularization for imaging in severely ischemic limbs; proceed directly to the operating room 4
• Do not assume embolic etiology without considering popliteal aneurysm thrombosis, especially if contralateral popliteal pulse is prominent 4
• Do not perform embolectomy alone if thrombosis of underlying atherosclerotic disease is discovered; address the stenotic lesion 5
• Recognize nonviable limbs early and proceed to amputation rather than futile revascularization attempts 5
• Always anticoagulate immediately even before definitive diagnosis to prevent thrombus propagation 6, 5