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Understanding embolism—A threat to life and limb
Blood clots are the most common culprit
Speed is of the essence


Types of embolism
Types of embolism

  • Cerebral embolism. A blockage of an artery supplying blood to the brain; it is a common cause of embolitic stroke.
  • Pulmonary embolism. A blockage of an artery supplying blood to the lungs; it can cause chest pain, breathlessness and sudden death.
  • Leg embolism. A blockage of an artery supplying blood to the leg; gangrene may develop below the blockage.
  • Arm embolism. A blockage of an artery supplying blood to an arm; it can cause pain, numbness, coldness and often muscle paralysis.


Who’s at risk?
Who’s at risk?

These medical conditions (including one device) put some people at a higher-than-average risk for developing arterial embolism:

  • Atrial fibrillation. Very rapid beating of the heart’s upper chambers.
  • Valve disease. Mitral valve, aortic or pulmonary stenosis caused by diseases such as rheumatic fever, endocarditis or congenital defects.
  • Prosthetic valve. A replacement for a diseased valve. Mechanical-type valves tend to promote clot formation more often than the biologic, or animal, type.
  • Endocarditis. A bacterial infection of the endocardium, the lining that covers the inner walls of the heart’s chambers and the valves.
  • Congestive heart failure. A condition resulting from the heart’s inability to pump sufficient blood to maintain normal circulation.
  • Heart attack. Damage to some portion of the heart muscle due to reduction or stoppage of blood flow to that site.
  • Deep vein thrombosis. A blood clot in a deep vein in the leg. A fragment can travel toward the lungs, where it can cause a pulmonary embolism.

In an average lifetime, the heart pumps 1 million barrels of blood—enough to fill 3.3 supertankers—with a precious cargo of oxygen and nutrients to nourish all the body’s cells.

But that same transport system can carry a hidden hazard—a wandering clump of material called an embolus—that forms elsewhere in the body, breaks loose and travels through the bloodstream to a distant blood vessel. The result: an embolism, or a blockage in the flow of blood in the legs, arms, lungs or brain.

Blood clots are the most common culprit

The material might be a piece of tissue or tumor, a mass of bacteria, a bit of bone marrow, a lump of cholesterol or calcium, or a globule of fat. However, the most common kind of emboli are blood clots, and the distant lodging place usually depends on the site of the original blood clot.

A pulmonary embolism, for example, is usually the result of a fragment from a deep vein thrombosis (a blood clot formed deep in a vein, most often in the leg) that travels to the lungs. A cerebral embolism or embolic stroke, on the other hand, generally begins as a blood clot in the lining of the heart after a heart attack or as the result of a damaged heart valve.

Embolisms are named for the part of the circulation affected (see “Types of Embolism”).

Speed is of the essence

An embolus can travel far from the original site of the blood clot in a matter of seconds. With a pulmonary embolism, the signs are sudden breathlessness and a feeling of faintness. The symptoms of embolic stroke depend on which part of the brain is affected; loss of vision, inability to speak, partial paralysis or loss of consciousness are among the possible symptoms.

In any case, there is little time to spare. Recovery depends on the speed with which blood flow is reestablished to the oxygen-deprived organ and on maintaining vital functions such as respiration, blood pressure, circulation and electrolyte balance. If there’s enough time, a doctor might first try dissolving the embolus with thrombolytic drugs. If not, a surgeon will perform an embolectomy by cutting into the artery and suctioning out the embolus that is causing the blockage.

Once the flow of blood is restored, the original source of the clot must be found and, if possible, removed. This is important because emboli tend to recur. With proper treatment the long-term prospects are good for the majority of patients who survive an embolism.