Arterial embolism is a sudden interruption of blood flow to an organ or body part. This is caused when the artery that supplies the blood to that organ or body part is blocked by an embolus (blood clot or atherosclerotic plaque) that has moved in the bloodstream from its point of origin to a new location.

The point of origin for the embolus can be the heart or a large blood vessel.

An embolus is a clot (or a piece of plaque that acts in the same manner as a clot) that travels from the site where it formed to another location in the body. The embolism can lodge in an artery at the new location and block the flow of blood there.

The blockage deprives the tissues in that location of its normal blood flow and oxygen (lack of blood and oxygen is called "ischemia"). This can result in damage or even death of the tissues (necrosis) in that organ.

Arterial embolism may be caused by a single embolus or multiple emboli.

Arterial emboli can affect the extremities -- especially the legs and feet. Some may involve the brain, causing a stroke, or the heart, causing a heart attack. Less common sites include the kidneys, gut (intestines), and the eyes.

A major risk for emboli is atrial fibrillation because the blood flow through the atria can be slow enough to trigger clots to form, which can then travel (embolize). The risk of an embolism increases when factors that tend to form clots are increased.

These may include injury or damage to an artery wall, hematologic (blood component) conditions associated with increased clotting (such as increased platelet count), and other disorders.

Another condition that poses a high risk for embolization (especially to the brain) is mitral stenosis. Endocarditis may also cause arterial emboli (paradoxical embolization), if a clot travels through a hole in the heart called the foramen ovale.

If an embolism involves the arteries supplying blood flow to the lungs, it is called pulmonary embolism, rather than arterial embolism, and it is a different condition (that is, clots originated in the veins, not the arteries). Endocarditis can also cause pulmonary embolism.

EMBOLIZATION IN AN EXTREMITY

• muscle pain in the extremity (see knee pain, foot pain)
• numbness and tingling in the extremity
• pale color of arm or leg
• decreased or absent pulse in the extremity
• decreased extremity temperature, the extremity feels cold to touch
• lack of movement of the extremity
• weakness of the extremity
• muscle spasm in the extremity
• body feels cool (fingers or hands)
• muscle function loss

Symptoms may begin abruptly or slowly depending on the size of the embolus and the extent to which it blocks the blood flow.

Later symptoms:

• blisters develop easily
• skin erosion (ulcer)
• skin necrosis (skin is dark and damaged)
• skin falling off (sloughing)

EMBOLI IN AN INTERNAL ORGAN (see complications)

• Symptoms of ischemia (lack of oxygen) or infarction (tissue death): varies with organ involved. There may be pain and/or temporary decreased organ function.

There may be decreased or absent pulse, and/or decreased or absent blood pressure in the extremity. There may be signs of tissue necrosis or gangrene.

Tests to diagnose arterial embolism or reveal the source of emboli may include:

• a Doppler ultrasound exam of an extremity
• transcranial Doppler
• echocardiography, transthoracic
• transesophageal echocardiography (TEE)
• myocardial contrast echocardiography (MCE)
• magnetic resonance imaging
• angiography of the affected extremity or organ
• renal arteriography
• extremity arteriography
• plethysmography
• a duplex Doppler/ultrasound exam of extremity

This disease may also alter the results of the following tests:

• isotope study
• platelet aggregation test
• factor VIII assay
• euglobulin lysis time (ELT)
• plasminogen activator inhibitor-1 (PAI-1) activity
• tissue-type plasminogen activator (t-PA) levels

Arterial embolism requires prompt hospitalization for treatment. The goals of treatment are to control symptoms and to improve the interrupted blood flow to the affected area of the body. Intravenous analgesics are administered for pain control.

Medications that improve blood flow by breaking up the clot are local thrombolytics (such as streptokinase). The development of new clots is prevented with anticoagulants (such as warfarin or heparin) or antiplatelet medications (such as aspirin, ticlopidine, and clopidogrel).

Surgical procedures may be appropriate for some people. These may include thromboaspiration (clot aspiration), embolectomy (clot removal through a balloon catheter or through open surgery), angioplasty (dilatation of the artery with a balloon catheter) with or without implantation of a stent, and bypass of the blood vessel.

The underlying cause of the emboli, if identified, should be treated to prevent further embolization.

The outcome varies depending on the location of the embolism and the extent that the embolism affects blood supply to the area. Arterial embolism can be serious if not treated promptly. It may be life-threatening, with a 25 to 30% death rate.

The affected area can be permanently damaged, with up to approximately 25% of cases requiring amputation of an affected extremity. Arterial emboli can recur even after successful treatment.

• infection in the affected tissue
• tissue death (necrosis) and gangrene of the extremity (See gas gangrene.) requiring amputation
• septic shock
• acute MI
• transient ischemic attack (TIA)
• stroke (CVA)
• temporary or permanent kidney failure
• temporary or permanent decrease/loss of other organ functions

Prevention of arterial embolization begins with prevention of the source of the embolus. For example, if a high risk for embolism is identified, blood thinners (such as Coumadin) may be prescribed to prevent formation of a blood clot that could be a source of the embolism.

Antiplatelet agents may also be needed. Measures to reduce atherosclerosis may reduce risk of an arterial embolus forming from a piece of atherosclerotic plaque. The risk for both atherosclerosis and clot formation/embolism increases in persons who smoke, are under stress, are overweight, or who lead a sedentary life.