What Is Atrial Fibrillation, How Is This Different From Normal Rhythm, And How Dangerous Is It?

Dr. Hugh Calkins answers the question: 'What Is Atrial Fibrillation?'

ByHugh Calkins, M.d., Director, Arrhythmia Service, Johns Hopkins Hospital
November 24, 2008, 9:47 AM

— -- Question: What is atrial fibrillation, how is this different from normal rhythm, and how dangerous is it?

Answer :Atrial fibrillation is a rapid chaotic rhythm in the upper chamber of the heart. And it's different than normal rhythm because normally the heart is a muscle and there's a timer on it that's a sinus node so during normal rhythm the upper chamber contracts and then the lower chamber contracts and there is a one for one relationship between the two.

When you develop atrial fibrillation the upper chamber suddenly starts beating at rapid rates -- 300 to 600 beats a minute -- in a very chaotic fashion, and that results in the lower chamber of the heart beating typically between 80 and 130 beats per minute, again in a rapid chaotic fashion.

Atrial fibrillation is not a life-threatening arrhythmia -- it doesn't suddenly cause you to die -- but it can be serious and that atrial fibrillation is closely linked to strokes. So if a patient has atrial fibrillation they have about a five-fold increased risk of stroke. Atrial fibrillation also has been shown to have a slightly shorter survival or life span, and that atrial fibrillation can cause symptoms.

So I think when we think about atrial fibrillation we think about risk of stroke and does a patient need to be on a blood thinner, we think about symptoms, do they have symptoms from the atrial fibrillation -- and many patients do. And we don't' think so much in terms of this is a heart rhythm that you're going to die from, because it's generally not life-threatening in that sense, it's more of a condition that increases stroke risk, sometimes can cause heart failure, and commonly causes symptoms that decrease one's quality of life.

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