Description

• Obstruction of the peripheral arteries secondary to embolism or thrombus (acute) or plaque (chronic)
• Caused by atherosclerosis or embolus
• Patients with PAD may also have coronary artery and cerebrovascular disease
• Epidemiology:
  • Risks factors (selected):
    • Age
    • Smoking
    • Diabetes
    • Hyperlipidemia
    • HTN
  • Associated with morbidity and mortality from other forms of atherosclerosis (coronary artery disease, stroke)
  • Complications:
    • Aneurysm
    • Thrombosis
    • Ulceration
    • Limb loss
• Chronic arterial insufficiency (CAI):
  • Progressive obstructing atherosclerotic disease causing subacute ischemia and pain (claudication)
  • Up to 10% develop critical leg ischemia
• Acute arterial insufficiency (AAI):
  • Caused by arterial thrombosis (50%) or embolism
  • Trauma (including iatrogenic)
  • Causes acute limb ischemia with signs and symptoms of the 6 Ps (below)
• Atheroembolism:
  • Caused by rupture or partial disruption of an atherosclerotic plaque (aorta, femoral, iliac)
  • Gives rise to cholesterol emboli that shower and obstruct arteriolar networks
  • May be precipitated by invasive arterial procedures such as cardiac catheterization

Etiology

• Obstruction by atherosclerotic plaques (CAI)
• Arterial thrombosis
• Arterial emboli:
  • Cardiac emboli from dysrhythmias, valvular heart disease, atrial myxoma, or cardiomyopathy (80%)
  • Aneurysms
  • Infection
  • Tumor
  • Vasculitis or foreign body
  • Thrombosis of plaques from pre-existing CAI
• Atheroembolism

Signs and Symptoms

• CAI:
  • Claudication:
    • Aching pain in the calves (femoropopliteal occlusion) or buttocks and thighs (aortoiliac region)
    • Occurs with activity and slowly relieved by rest or dependent positioning
    • Classic claudication presents in about 1/2 of patients with PVD
  • Severe disease presents with:
    • Limb pain at rest, usually starting in the foot
    • Rapidly progressive claudication or ulceration
    • Usually exacerbated at night with relief of pain when foot is hung off the bed
• AAI:
  • Extremity pain:
    • Sudden onset
    • Gradual increase in severity
    • Starts distally and moves proximally over time
    • Decrease in intensity once ischemic sensory loss occurs
    • Embolism can occur proximally and move more distally in a minority of cases
• Atheroembolism:
  • Complaint of cold and painful fingers or toes
  • Small atherosclerotic emboli may affect both extremities
  • Usually related to recent arteriography, vascular, or cardiac surgery
  • Can be related to aneurysm and/or stenotic disease of a more proximal source
  • Multiorgan involvement is common (renal, mesentery, skin, others)

• CAI:
  • Absent or decreased peripheral pulses
  • Delayed capillary refill with cool skin
  • Increased venous filling time
  • Bruits
  • Pallor and dependent rubor of the leg
  • Muscle and skin atrophy
  • Thickened nails and loss of dorsal hair
  • Ulcerations (especially toes or heels) or gangrene with severe disease
• AAI:
  • 6 Ps:
    • Pain (first, sometimes only symptom)
    • Pallor
    • Pulselessness
    • Poikilothermic
    • Paresthesias (late finding)
    • Paralysis (late finding)
  • Identification of a source of a possible embolic process is crucial (atrial fibrillation, cardiomegaly)
  • Assess paralysis segmentally in the limb by isolating muscle groups (i.e., holding the calf to assess intrinsic muscles of the foot)
• Atheroembolism:
  • Ischemic and painful digits
  • “Blue-toe syndrome”
  • Livedo reticularis

Essential Workup

• CAI:
  • Ankle–brachial index (ankle systolic BP divided by higher arm systolic BP)
  • Formal arterial doppler
  • Bedside test to determine whether CAI is present (see NEJM video reference)
  • Ratio of <0.9 is abnormal and <0.4–5 indicates severe disease
  • Calcific arteries (diabetes) can have false-negative ABI or elevated ABI (>1.3)
• AAI:
  • Physical diagnosis using the 6 Ps
  • Those with acute-on-CAI tolerate limb ischemia better than those without CAI, due to well-developed collateral circulation
• Atheroembolism:
  • Clinical diagnosis: Affected areas painful, tender, and may be either dusky or necrotic
  • Workup may investigate source of emboli with duplex US, CT angiogram, ECG

Diagnostic Tests and Interpretation

• CBC
• Electrolytes, BUN, creatinine, glucose
• Coagulation studies
• Creatine phosphokinase to evaluate for ischemia
• Special tests for suspected etiologies:
  • Hold blood for hypercoagulable studies
  • Sedimentation rate and CRP for vasculitis
  • Blood cultures for endocarditis

• Doppler US:
  • Visualizes both venous and arterial systems
  • Identifies level of arterial occlusion, as well as thrombosis and aneurysm
  • Sensitivity and specificity >80–90% for occlusion of vessels proximal to the popliteal vessels
• Plethysmography/segmental pressure measurements:
  • Uses measurements of the volume and/or limb pressure to characterize the arterial perfusion
  • Variable availability depending on the quality of the duplex technician as well as the equipment utilized
  • Approximates US in sensitivity and specificity
• Angiography:
  • Determines details about the anatomy, including the level of occlusion, stenosis, and collateral flow
  • Useful where the diagnosis of AAI is uncertain or before emergent bypass grafting
  • Advantage is intervention (atherectomy, angioplasty, percutaneous thrombectomy, and/or intraluminal thrombolytics) can be done at the time of diagnosis
  • Can be used to plan future open revascularization
• CT angiogram:
  • CT is useful for diagnosis of occlusive aortic disease or dissection
  • Rapidly available and reliable
  • Many centers have moved to CT angiogram as the first-line diagnostic tool. The decision for operative or angiographic intervention is based on the CT angiogram
  • Requires contrast, therefore may not be first line for patients with renal insufficiency
• MRI:
  • Sensitive for evaluation of CAI and dissection
  • Plaques can be identified within the vasculature
  • Disadvantages are that MRI is time consuming and expensive, therefore, limiting its utility in the ED

Differential Diagnosis

• Acute thrombosis or emboli
• Arterial dissection
• Deep venous thrombosis
• Venous insufficiency
• Venous aneurysm
• Popliteal entrapment syndrome
• Baker cyst
• Extrinsic mass compression (i.e., tumor)
• Compartment syndrome
• Buerger disease
• Spinal stenosis
• Neuropathy
• Bursitis
• Arthritis
• Reflex sympathetic dystrophy

Pre Hospital

• Maintain hemodynamic stability with fluids
• Apply cardiac monitor to assess for potential dysrhythmia
• Place the ischemic limb at rest and in a dependent position
• Provide oxygen if low oxygen saturation or pulmonary symptoms

Initial Stabilization/Therapy

• IV fluid bolus for hypotension
• ECG, monitor, pulse oximetry
• Supplemental oxygen
• Pain control
• Avoid temperature extremes

Ed Treatment/Procedures

• CAI:
  • Antiplatelet therapy with aspirin 81–325 mg/d or clopidogrel 75 mg/d may be used as first-line treatment. Dual therapy has not been shown to improve outcomes, although may be indicated in other forms of atherosclerosis
  • Other drugs include: Cilostazol 100 mg b.i.d, pentoxifylline 400 mg t.i.d, and dipyridamole 200 mg b.i.d
  • Revascularization depending on the severity and location of obstruction:
    • Balloon angioplasty with possible stent placement
    • Atherectomy
    • Bypass grafting
  • Risk-factor modification:
    • Tobacco cessation
    • Aggressive management of hyperlipidemia, HTN, diabetes
    • Exercise therapy
• AAI:
  • Limit further clot propagation with IV heparin 80 U/kg IV bolus → 18 U/kg/hr IV gtt
  • Do not anticoagulate patients suspected of having an aortic dissection or symptomatic aneurysm
  • Emergent consultation with vascular surgery or interventional specialty (radiology and/or cardiology):
    • To determine which diagnostic study is best to make the diagnosis
    • To begin arrangements for possible operative therapy and/or other intervention
    • Options for operative therapy include percutaneous thrombectomy, embolectomy, angioplasty, regional arterial thrombolysis, bypass grafting
    • Blood flow to the affected limb must be re-established within 4–6 hr after onset of ischemic symptoms
  • Complications of AAI include:
    • Compartment syndrome
    • Irreversible ischemia requiring amputation
    • Rhabdomyolysis, renal failure
    • Electrolyte disturbances
• Atheroembolism:
  • Treat conservatively if a limited amount of tissue is involved and renal function is not significantly compromised
  • No clear therapy for the ischemic digits besides supportive wound care and analgesia
  • Formal arterial US
  • Some studies have tried corticosteroids to decrease inflammation, statins to stabilize plaque, aspirin, or dipyridamole
  • Amputation for irreversibly necrotic toes
  • Vascular surgeon referral within 12–24 hr of ED visit
  • Prevent further embolic events by a thorough investigation and correction of the source of atheroemboli

Medication

• Aspirin: 81–325 mg PO per day
• Cilostazol: 100 mg PO b.i.d
• Clopidogrel: 75 mg PO per day
• Heparin: 80 U/kg bolus IV followed by 18 U/kg/hr IV
• Pentoxifylline: 400 mg PO t.i.d
• Medical optimization (antiplatelet agents, statins, control of hypertension, diabetes, cardiac and renal functions)

Disposition

• All patients with AAI are admitted for evaluation and revascularization
• CAI: Consider admission for rapidly progressive claudication or ischemic pain at rest:
  • To undergo heparinization and angiography to rule out an acute thrombosis
• Atheroembolism admission indicated with large areas involved, significant pain, infection, or renal compromise

• Atheroembolism:
  • If they have small lesions, adequate pain control, no evidence of renal compromise or superinfection, and follow-up within 24 hr
• CAI:
  • No evidence of rapid progression, critical leg ischemia, gangrene, or infection

• CAI will need urgent referral to vascular surgery
• Atheroembolism, depending on the origin of the emboli, may need referral to vascular surgery or to cardiology

Follow-Up Recommendations

CAI without acute ischemia and atheroembolism with minimal involvement should have close follow-up to evaluate the extent of their disease

See Also

• Arterial Occlusion
• Venous Insufficiency