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Heart Arrhythmia

What Causes an Arrhythmia?

Each heart beat is triggered by an electrical signal that begins in a group of cells called the sinus node or sinoatrial (SA) node. From the SA node, the electrical signal travels through special pathways in the right and left atria. The electrical signal then moves down to a group of cells called the atrioventricular (AV) node. The electrical signal then leaves the AV node and travels along a pathway called the bundle of His. This pathway divides into a right bundle branch and a left bundle branch.

The ventricles then relax, and the heartbeat process starts all over again in the SA node.

A problem with any part of this process can cause an arrhythmia. For example, in atrial fibrillation, a common type of arrhythmia, electrical signals travel through the atria in a fast and disorganized way. This causes the atria to quiver instead of contract.

Who Is At Risk for an Arrhythmia?

Arrhythmias are more common in people who have diseases or conditions that weaken the heart, such as:

Other conditions also can increase the risk for arrhythmias, such as:

Also, several other risk factors can increase risk for arrhythmias. Examples include heart surgery, certain drugs (such as cocaine or amphetamines), or an imbalance of chemicals or other substances (such as potassium) in the bloodstream.


Reference: The National Heart, Blood, and Lung Institute.

Last updated April 16, 2017