Arterial Embolus & Thrombosis
Description of Medical Condition
The acute loss of perfusion distal to an occlusion of a major artery due to an embolus which migrates to the point of occlusion or a clot intrinsic to the point of occlusion (thrombosis). Both are true emergencies. Following obstruction of an artery, a soft coagulum forms both proximally and distally in the areas of stagnant flow. As the clot extends, collateral pathways are involved and the process becomes self-propagating. Ultimately, the venous circulation can be involved. The extent of vascular compromise is critical and determines the “golden” period of four to six hours. After this time, the profound ischemia leads to cellular death and is irreversible.
System(s) affected: Cardiovascular, Hemic/Lymphatic/lmmunologic
Genetics: Can be associated with inheritable hyper-coagulable and premature atherosclerotic syndromes
Incidence/Prevalence in USA: 50-100/100,000 hospital admissions. A leading cause of death and limb loss in the elderly.
Predominant age: Elderly
Predominant sex: Male > Female
Medical Symptoms and Signs of Disease
• To estimate occlusion location
– Symptoms typically start one joint below occlusion
– Palpable pulses are absent below an occlusion and are accentuated above
• The five “P’s”: Pain, Pulselessness, Pallor, Paresthe-sias, and Paralysis. If any one is present, frequent re-evaluations indicated. Proximal occlusions lead to a more rapid progression of findings. Occlusion at the aortic bifurcation can produce bilateral findings.
– Pain: Diffuse in distal area. If persists, crescendo in nature. Predominates as first symptom in embolism. Not alleviated by change of position.
– Pulselessness: Mandatory for the diagnosis of embolism or thrombosis. Pedal pulses subject to observer error. Always compare to the opposite limb.
– Pallor: Skin color pale early, cyanotic later. Check extremity temperature left to right and top to bottom. Look for signs of chronic ischemia — skin atrophy, loss of hair, thick nails.
– Paresthesia: Numbness early with thrombosis. Light touch first to be lost. Not reliable in diabetics. Loss of pain and pressure indicate advanced ischemia.
– Paralysis: Motor defect occurs after sensory and indicates profound ischemia
• Distribution of emboli
– Femoral artery 30%
– Iliac artery 15%
– Aortic bifurcation 10%
– Popliteal artery 10%
– Brachial 10%
– Mesenteric arteries 5%
– Renal 5%
– Cerebral — estimated 15-20%
What Causes Disease?
• Emboli
– Cardiac
– Atrial flutter/fibrillation
– Valve disease
– Myocardial infarction
– Cardiomyopathy
– Cardiac tumors
– Endocarditis
– Aneurysms — cardiac, aortic, peripheral
– Paradoxical
• Thrombosis:
– Atherosclerotic occlusive disease
– Aortic and peripheral aneurysms — especially popliteal
– Hypercoagulable states
– Venous gangrene
– Drug abuse
– Heparin allergy
– Vascular bypass
• Trauma:
– Blunt
– Penetrating
– Vascular and cardiac interventional procedures
Risk Factors
• Drug abuse
Diagnosis of Disease
Differential Diagnosis
Emboli vs thrombosis
• Emboli
– Myocardial diseases — myocardial infarction, arrhythmias — atrial fibrillation
– Aneurysms
– Pain as first symptom
• Thrombosis
– Absence of heart disease — arrhythmias/infarction
– Chronic vascular history
– Bilateral changes of chronic ischemia
– Numbness rather than pain as first symptom
– Vascular procedures — bypass/interventional
• Acute aortic dissection; chest or back pain
• Acute deep vein thrombosis; massive swelling and warm skin
• Low flow states
Laboratory
• Acute diagnosis is by history and exam: Laboratory data is for preoperative evaluation, elucidation of etiology, or documentation of severity of ischemia. 0EKG
– Myocardial/muscle isoenzymes
– Coagulation parameters
– Blood pH/bicarbonate
– Urine myoglobin
– Electrolytes
Drugs that may alter lab results: N/A
Disorders that may alter lab results: N/A
Pathological Findings
N/A
Special Tests
• Noninvasive — indirect:
– Doppler: presence or absence of flow
– A/ai (ankle/arm index) = dorsal pedal/posterior tibial pressure + by brachial pressure; a/ai > 0.30 favorable
• Noninvasive — direct
– Duplex imaging if time permits
Diagnostic Procedures
• Arteriography
– Rarely indicated preoperatively in threatened limb
– May help differentiate thrombosis from embolus in non-threatened limb
– Useful with occluded grafts
Treatment (Medical Therapy)
Appropriate Health Care
Based on detailed exam, history, and Doppler exam. Triage determines appropriate therapy.
• Viable
– Mild ischemicpain
– Normal neurologic exam
– Capillary refill present
– Arterial signals present by Doppler in distal extremity
– A/ai > 0.30
• Threatened
– Ischemicpain OMild neurologic deficit
– Weakness of dorsiflexion
– Minimal sensory loss- light touch and/or vibratory
– No pulsatile flow by Doppler
– Venous flow present
• Major ischemic changes — irreversible
– Profound sensory loss
– Muscle paralysis
– Absent capillary refill
– Skin marbling
– Muscle rigor
– No arterial or venous signals by Doppler
General Measures
• Time is of the essence
• In the threatened category nothing should delay appropriate therapy
• Unless contraindicated, systemic heparinization to decrease clot propagation and prophylaxis against further emboli
• Resuscitation and stabilization of patient to extent permitted by time
• Viable — symptomatic
– Heparin
– Arteriography
– Embolism
– Surgical removal if acceptable operative risk, e.g. balloon embolectomy
– Anticoagulation vs intraarterial thrombolytics if prohibitive risk
– Thrombosis
– Trial of thrombolytics and correction of arterial defect if good risk
– Anticoagulation if poor risk or thrombolytics contra-indicated
• Threatened — salvageable
– Heparin
– Minimal delay to definitive therapy
– Arteriography
– Individualized thrombolysis and/or operative procedure (depending on extent of thrombosis and amenability for surgical removal)
– Thrombolysis to optimize alternatives
– Adjunctive operative therapy
– I ntraoperative lytic therapy
– Bypass
– Patch angioplasty
• Major ischemia — irreversible
– Arteriography usually not warranted
– Attempts at repertusion contraindicated
– Anticoagulation
– Definitive amputation if possible
Surgical Measures
See General Measures
Activity
N/A
Patient Education
N/A
Medications (Drugs, Medicines)
Drug(s) of Choice
• Heparin
0100 units/kg IV loading dose (approximately 5,000- 10,000 units)
– Continuous heparin infusion sufficient to double the PTT, generally 1000 to 1500 units/hour
• TPA/Urokinase
– Refer to manufacturer’s literature
Contraindications:
• Heparin
– Allergy
– Bleeding diathesis Trauma (e.g., head injury)
– Hematuria/hemoptysis
– Acute aortic dissection
• Tissue plasminogen activator (TPA/Urokinase)
– Non-salvageable ischemia
– Recent Ml OAneurysm
– Aortic dissection
– Trauma
– Uncontrolled hypertension
– Recent operative procedure
Precautions: N/A
Significant possible interactions: N/A
Alternative Drugs
Lie thrombolytics in development
Patient Monitoring
• Post operative monitoring: OAnticoagulation
– Establish brisk diuresis
– Continued resuscitation and diagnosis including echocardiography and other studies
– Monitor perfusion stability
– Treat/eliminate causative factors
Prevention / Avoidance
• Chronic anticoagulation in atrial arrhythmia
• Reduction of risk factors for atherosclerosis
Possible Complications
• Acidosis
• Myoglobinuria
• Hyperkalemia
• Recurrent occlusion
• Failure to remove clot/obstruction
• Compartment syndromes/reperfusion syndrome; delayed or instant
– Predisposing factors include: combined arterial injury, profound and prolonged ischemia, hypotension
– Occurs both in upper and lower extremities
– Clinical findings
– Severe pain
– Pain with passive muscle movement
– Hypesthesias of nerves in compartment
– Paralysis of nerves especially peroneal — foot drop
– Tender, tense edema
– Compartment pressure > 30-45 mm Hg
– Consequences of unrecognized compartment syndrome — acute
– Amputation
– Sepsis
– Myoglobin renal failure
– Shock
– Multiple organ failure
– Delayed
– Ischemic contracture
– Infection
– Causalgia
– Gangrene
– Treatment
– Fasciotomy
Expected Course / Prognosis
• 90% good outcome with prompt treatment
• Delayed/untreated associated with high mortality and limb loss
• 20-30% hospital mortality associated with causative factors
Miscellaneous
Associated Conditions
• Acute mesenteric ischemia
• Renal infarction
• Carotid/CVA
• Multiple emboli
• Digital microembolization
Age-Related Factors
Pediatric: Rare in children
Geriatric: Most common age affected
Pregnancy
Rare
International Classification of Diseases
444.0 Arterial embolism and thrombosis of abdominal aorta
444.21 Arterial embolism and thrombosis of arteries of upper extremity
444.22 Arterial embolism and thrombosis of arteries of lower extremity
444.81 Arterial embolism and thrombosis of iliac artery 444.9 Arterial embolism and thrombosis of unspecified artery
See Also
Abbreviations
A/ai = Ankle/arm index
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