What Is Stroke?

Understanding "Stroke" and "Cardioembolic Stroke"

It is a known fact that stroke occurs when the blood supply to a part of the brain is interrupted or severely reduced.  That event deprives brain tissue of oxygen and nutrients. A few minutes after that occurs brain cells begin to die.  The result is that abilities controlled by that area of the brain are lost. These abilities can include speech, movement, vision and memory.

Did you know that there are two basic types of stroke:

1. Ischemic (blockage of an artery).

2. Hemorrhagic (rupture of an artery).

History shows that About 80 percent of strokes are ischemic strokes. This type of stroke occurs when blood clots, then plaque or vegetation block arteries to the brain.  That results in damage to brain tissue.   Ischemic strokes are either embolic or thrombotic.

In the case of an embolic stroke, a blood clot forms somewhere in the body, usually the heart.  That clot travels through the blood stream to the brain. As the it enters the brain it will continue until it lodges in a small blood vessel blocking blood.  At that point the clot flow beyond that point cut off, resulting in a stroke. This type of blood clot is called an embolus.

It is estimated that 25% of ischemic strokes are cardioembolic.  A cardioembolic stroke occurs when the embolus has traveled from the heart. There are some 125,000 cases of cardioembolic strokes yearly in the United States.

These strokes can not be considered a single disease process as there are many different types of cardiac disorders that lead to cardioembolic stroke.  Each of them has unique clinical features, risks of initial and recurrent stroke, and optimal therapy.

Cardioembolic Stroke

Clot forming heart diseases include atrial fibrillation, a recent heart attack, dilated cardiomyopathy (stretching and poor pumping action of the heart chambers) and diseases of the heart valves.

Such discorders tend to cause blood flow to slow down in parts of the heart.  When the movement of blood slows it tends to clot. To prevent these clots doctors put prescribe medications that help reduce their occurrence.

Atrial fibrillation (AF) is the most common heart condition that causes stroke. This type of stroke is caused when the two upper chambers of the heart (atria) beat rapidly and unpredictably. This causes the atrial walls to wriggle without contracting.

Blood flow tends to slow down in this non-beating chamber, allowing clots to form. AF increases stroke risk up to six times. About 15 percent of all people who have a stroke have AF.

Diagnosis of Cardioembolic Stroke

Traditionally, an echocardiogram is used to evaluate the heart in stroke victims. Echocardiograms use ultrasound to look inside the heart for clots and other potential causes of cardioembolic stroke.

The combination of magnetic resonance imaging and echocardiography of the heart provides the optimal imaging assessment of stroke patients, leading to improved detection of not only the potential source of the stroke, but the underlying cause.

More information can be found at http://www.SIRweb.org.

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                   What Is Stroke?