Perioperative management - Transfemoral Fogarty balloon catheter embolectomy in embolic occlusion of the left external iliac artery—Vascular Surgery

• Arterial embolism resulting in acute limb ischemia

80-90% of all peripheral emboli originate from thrombi in the left atrium, and 70% of all peripheral emboli involve the aortoiliac axis. Vascular branches are most often affected, especially the femoral bifurcation and the popliteal level.

More than 70% of cardiac embolisms are by absolute arrhythmia in atrial fibrillation. Other sources of cardiac embolisms:  acute myocardial infarction (5%); dilated cardiomyopathy; valve defects; endocarditis; prosthetic heart valve replacement; heart wall aneurysm; and atrial myxoma.

10-20% of all peripheral thromboembolism are caused by non-cardiac sources of embolism: Aneurysms of the aortoiliac and femoropopliteal axis (microembolism -> "blue toe syndrome" or "trash foot" ); arteriosclerotic plaques; rarely tumors (lung cancer, pulmonary metastases with connection to the pulmonary circulation, angiosarcoma); foreign bodies; or paradoxical embolism in patent foramen ovale cordis.

In 5-10% of cases, the origin of a peripheral arterial embolism is unknown.

• ASA IV

The diagnosis of acute limb ischemia can often be made "at a glance" after a brief history and examination. Normally, angiography is not performed (exception: concurrent PAOD) and management is planned based on the clinical findings (history, inspection, palpation). After having resolved the absolute ischemia, diagnosis and treatment of the source of the embolism can be approached in orderly fashion.

Emergent diagnostic work-up should address the following questions:

1. Severity of ischemia (Pratt's 6 Ps, TASC in PAOD)?
2. Localization and extent of the occlusion?
3. Acute ischemia resulting from embolization or PAOD?

The typical 6 Ps of Pratt characterize the severe course of acute limb ischemia with grave threat to the limb viability (Source: Pratt GH (1954) Cardiovascular surgery. Kimpton, London):

In PAOD, the classification of acute limb ischemia according to the Transatlantic Inter-Society Consensus (TASC) Working Group seeks to reflect the varying levels of urgency for further diagnostic work-up and management:

Medical history/clinical picture

Rough distinction between acute thrombotic occlusion and embolism:

→ Embolism

• Sudden, occasionally whip-like pain in the limb (cardinal symptom)
• Often severe ischemia
• Cardiovascular history: known atrial fibrillation; heart defect; history of myocardial infarction; aortic aneurysm

→ thrombotic occlusion

• more likely symptoms increasing over several days, typically with incomplete ischemia
• Known PAOD (claudication symptoms?)
• History of bypass surgery, stenting/PTA
• Atherosclerosis risk profile
• Local trauma
• No evidence of source of the embolism

Skin color

• White ischemia: pale distal to the occlusion
• Blue ischemia: less favorable prognosis because thrombus formation due to stasis has already spread to the venous circulation
• Spontaneous Ratschow test may be seminal in incomplete ischemia (total pallor with the limb elevated and no recovery even after returning the limb to the horizontal position).

Capillary refill time

• short plantar pressure with finger on big toe or forefoot → initially pale pressure point usually turns red within < 3 seconds
• The longer the redness takes to appear, the more marked is the perfusion disorder

Effective perfusion pressure

• Elevation of the limb allows the perfusion pressure to be estimated → 10 cm = 7.5 mmHg

Skin temperature

• The affected limb is colder when comparing both extremities
• The occlusion is much more proximal than the drop in temperature

Pulses

• In the simplest case, lack of pulses in the affected limb
• Bilateral lack of pulses: pre-existing bilateral PAOD or asymptomatic embolism

Auscultatory bilateral comparison of the limb arteries

Ankle-Brachial Index (ABI)

• ABI = systolic BP of posterior tibial artery / systolic BP of brachial artery
• the smaller the ABI, the more pronounced the ischemia
• In acute stages, the pressure might not be measurable

Color-flow Doppler ultrasonography

• Carotid artery, abdominal aorta, limb arteries (rule out popliteal aneurysm in lower leg occlusion!)
• Stenoses and occlusions in almost all vascular regions apart from chest
• Allows quantifying the degree of stenosis and assessing plaque morphology
• Sensitivity and specificity around 90%   

CT angiography

• Multislice computed tomography (MS-CT) with nonionic contrast agent
• Broad range of indications: traumatic vascular lesion (esp. trunk); vascular dissection/rupture; aneurysm; arterial thrombosis/embolism; portal vein/mesenteric vein thrombosis; pulmonary artery embolism; PAD; vascular tumors
• Benefits: rapid; detects relevant comorbidities; visualizes peripheral arteries; sensitivity and specificity each about 90%
• Drawbacks: Radiation and contrast agent exposure, allergies (about 3%), no functional assessment
• Indication does not depend on the degree of ischemia but on the history and clinical findings in the contralateral leg: angiography is recommended in case of pre-existing PAOD or evidence of popliteal aneurysm. The findings then determine the surgical strategy. The presence of concomitant PAOD or popliteal aneurysm as the origin of acute ischemia necessitates more complex repair (e.g., interposition grafts, bypass procedures). However, in case of complete ischemia do not waste too much time on angiography (suitable logistics).

Laboratory panels

• Blood count
• Electrolytes
• Coagulation
• Kidney function parameters
• Liver function parameters
• Blood lipids
• Blood group

Cardiac check

• Resting ECG

Chest x-ray

As an emergency measure administer 5000-10000 IU heparin to prevent appositional thrombosis. Protect the foot in a padded bootie to prevent pressure injury (especially during surgery as well!).

Acute limb ischemia is a vascular emergency, so measures taken as part of special preparation should be limited to the bare essentials.

• Shaving the surgical field
• While packed RBCs are usually not required, the blood group should be known.
• In advanced ischemia and acute threat to limb viability and patient life, the fasting criteria may not be met

General surgical risks

• Major bleeding, blood transfusions, transmission of hepatitis/HIV through allogeneic blood transfusions
• Allergy/intolerance
• Wound infection
• Thrombosis/embolism
• Skin/vascular/nerve damage, e.g., due to patient positioning
• Keloid

Procedure-specific risks

• Repeated vascular occlusion, possibly repeat procedure, (partial) amputation
• Vascular dissection/rupture by the balloon catheter, mange by stenting or venous interposition or prosthetic graft, if necessary
• Massive infections with severe bleeding from the suture lines, sepsis, amputation
• Nerve injury with paresthesia or pain, weakness or partial limb paralysis
• Embolism during withdrawal of the balloon catheter, e.g., gangrene in the foot, amputation
• Lymphedema
• Impaired renal function induced by contrast agent during intraoperative angiography