Description

• Acute loss of perfusion distal to occlusion of major arteries due to an embolus (air, fat, amniotic fluid) that migrates to point of occlusion or a thrombus (most common) intrinsic to point of occlusion; both are true emergencies.
• Following obstruction of the artery, clot extends both proximally and distally, collateral pathways become involved, and process becomes self-propagating. Ultimately, venous circulation can become involved.
• Golden period of 4 to 6 hours, after which ischemia leads to irreversible cellular death
• Distribution of emboli: femoral artery, 28%; aortoiliac, 18%; popliteal artery, 17%; brachial, 10%; mesenteric arteries, 5–7%; cerebral, ~15–20%; other, 9%
• Classic presentations
  • Blue toe syndrome: sudden painful, cool, blue toe in the presence of palpable distal pulses
  • Mesenteric ischemia: pain out of proportion to abdominal physical exam; typically begins periumbilically and then pain diffuses

Epidemiology

Incidence

• 50 to 100/100,000 hospital admissions annually
• Limb ischemia: 13 to 17/10,000 people per year

Prevalence

• Predominant age: elderly (>65 years)
• Predominant sex: male > female
• A leading cause of limb loss in elderly
• More common in African Americans

Etiology and Pathophysiology

Thrombosis in arterial circulation due to platelet aggregation and adhesion (not fibrin clot formation, as in venous thrombosis)

• Emboli
  • Arise from degenerative, stenotic, and ulcerative atherosclerotic plaques
  • Bilateral lower extremity disease signifies proximal aortic source.
  • Unilateral lower extremity embolic disease signifies disease distal to aortic bifurcation.
  • Emboli more commonly lodge in areas of bifurcation
• Cardiac
  • Atrial flutter/fibrillation
  • Valve disease and/or endocarditis
  • Myocardial infarction
  • Cardiomyopathy (low ejection fraction)
• Thrombosis
  • Atherosclerotic occlusive disease
  • Hypercoagulable states
  • Low-flow states
  • Entrapment syndrome
  • Venous gangrene
  • Drug abuse
  • Heparin-induced thrombocytopenia
  • Vascular bypass/grafts
• Trauma
  • Blunt or penetrating
  • Vascular/cardiac interventional procedures
• Aneurysms: cardiac, aortic, peripheral
• Paradoxical embolus: transit from right to left atria via patent foramen ovale

Genetics
Can be associated with inheritable hypercoagulable and premature atherosclerotic syndromes

Risk Factors

Tobacco abuse, endocarditis, diabetes, drug abuse, cardiac arrhythmia, atherosclerotic disease, trauma, DVT, large vessel aneurysmal disease, prior lower extremity revascularization

General Prevention

Anticoagulation in atrial arrhythmia, reduction of atherosclerosis risk factors, smoking cessation