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Atrial Fibrillation

Atrial Fibrillation
Atrial Fibrillation
Causes and Risk Factors

Atrial fibrillation
More than 30% of older Americans experience atrial fibrillation (AF), due to heart disease or conditions that increase the risk of AF. But what is this condition? What causes AF and what types of atrial fibrillation are diagnosed? Continue reading here for more information.

What is atrial fibrillation?
Atrial fibrillation (AF) is the most common type of arrhythmia. An arrhythmia is a problem with the speed or rhythm of the heartbeat.

What happens during atrial fibrillation?
During AF, the heart's electrical signal begins in a different part of the atria or the nearby pulmonary veins and is conducted abnormally. The signal doesn't travel through normal pathways, but may spread throughout the atria in a rapid, disorganized way. This can cause the atria to beat more than 300 times a minute in a chaotic fashion. During AF, the ventricles may beat up to 100-175 times a minute, in contrast to the normal rate of 60-100 beats a minute.

When this happens, blood isn't pumped into the ventricles as well as it should be, and the amount of blood pumped out of the ventricles is based on the randomness of the atrial beats. In AF, instead of the body receiving a constant, regular amount of blood from the ventricles, it receives rapid, small amounts and occasional random, larger amounts, depending on how much blood has flowed from the atria to the ventricles with each beat.

Types of atrial fibrillation
AF may be brief, with symptoms that come and go and end on their own, or it may be persistent and require treatment. Or, AF can be permanent, in which case medicines or other interventions can't restore a normal rhythm. Atrial fibrillation is generally classified as either:

  1. Occasional - symptoms come and go, lasting for a few minutes to hours and then stop on their own; also called "paroxysmal atrial fibrillation"
  2. Chronic - symptoms may last until treated

Subtypes of atrial fibrillation

Paroxysmal atrial fibrillation - the abnormal electrical signals and rapid heart rate begin suddenly and then stop on their own; symptoms can be mild or severe and last for seconds, minutes, hours, or days

Persistent atrial fibrillation - a condition in which the abnormal heart rhythm continues until it's stopped with treatment

Permanent atrial fibrillation - a condition in which the normal heart rhythm can't be restored with the usual treatments

What medical conditions or situations can cause the heart to go into fibrillation?  Learn more about the heart's electrical system and how you can avoid certain risks of atrial fibrillation (AF) in the next section.  More info on atrial fibrillation cause here.

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