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Atrial Fibrillation (AFib) is a common condition. It is well tolerated by most people who have it. Treatment however can be somewhat complicated and frustrating at times. In addition, it can be associated with strokes and other complications, and therefore deserves careful evaluation.
The mechanism of the arrhythmia is illustrated above. Instead of the regular initiation of the heart beat in the sinus node (as is illustrated graphically on HeartPoint's arrhythmia page), there is no single place the heart beat "starts" in the atrium. Wavefronts of activity (illustrated by the wavy arrows) spread throughout the atrium in a random pattern, simply finding another small island of tissue to depolarize. There is no effective contraction of the atrial muscle in this situation.
The lower chambers, the ventricles, continue to depolarize in a normal pattern. Their activity begins in the AV node and spreads down to the ventricles through specialized conduction tissues in the normal fashion. The rate of ventricular activation is often quite high and almost always quite irregular. This is due to the fact that many of the waves of fibrillation from the atrium reach the AV node, and they do so in an irregular pattern.
To learn more about atrial fibrillation, read on.
©COPY;1997 HeartPoint Updated December 1997
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