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Types of Arrhythmias

An arrhythmia (also called dysrhythmia or irregular heart rhythm) is an irregular or abnormal heartbeat. These are the common types of arrhythmias:

Supraventricular arrhythmias

  • These are arrhythmias that begin above the ventricles.
  • "Supra" means above and "ventricular" refers to the lower chambers of the heart (ventricles).

Premature atrial contractions (PACs)

Early extra beats that originate in the atrial (upper chamber of the heart)

Paroxysmal supraventricular tachycardia (PSVT)

A rapid, usually regular rhythm, originating from above the ventricles. PSVT begins and ends suddenly.

Accessory pathway tachycardias (bypass tract tachycardias)

A rapid heart rhythm due to an extra abnormal pathway or connection between the atria and the ventricles. The impulses travel through the extra pathways (short cuts) as well as the normal AV-HIS Purkinje system. This allows the impulses to travel around the heart very quickly, causing the heart to beat unusually fast (example: Wolff-Parkinson-White syndrome).

AV nodal reentrant tachycardia (AVNRT)

A rapid heart rate due to more than one pathway through the AV node.

Atrial tachycardia

A rapid heart rhythm originating in the atria.

Atrial fibrillation

A very common irregular heart rhythm. Many impulses begin and spread through the atria, competing for a chance to travel through the AV node.

The resulting rhythm is disorganized, rapid, and irregular. Because the impulses are traveling through the atria in a disorderly fashion, it results in loss of coordinated atrial contraction

Atrial flutter

An atrial arrhythmia caused by one or more rapid circuits in the atrium. Atrial flutter is usually more organized and regular than atrial fibrillation.

Ventricular arrhythmias

These are arrhythmias that begin in the lower chambers of the heart.

Premature ventricular contractions (PVCs)

PVCs are early extra beats beginning in the lower chambers of the heart (ventricles). PVCs are common. Most of the time they cause no symptoms and require no treatment. In some people, PVCs can be related to stress, too much caffeine or nicotine, or exercise. But sometimes, PVCs can be caused by heart disease or electrolyte imbalance. People who have a lot of PVCs, and/or symptoms associated with them, should be evaluated by a heart doctor. Learn more about premature ventricular contractions.

Ventricular tachycardia (V-tach)

A rapid rhythm originating from the lower chambers of the heart. The rapid rate prevents the heart from filling adequately with blood, and less blood is able to pump through the body. This can be a more serious arrhythmia, especially in people with heart disease, and may be associated with more symptoms. A heart doctor should evaluate this arrhythmia.

Ventricular fibrillation

An erratic, disorganized firing of impulses from the ventricles. The ventricles quiver and are unable to contract or pump blood to the body. This is a medical emergency that must be treated with cardiopulmonary resuscitation (CPR) and defibrillation as soon as possible. (Learn more about sudden cardiac death)

Long QT Syndrome

The QT interval is the area on the electrocardiogram (EKG) which represents the time it takes for the heart muscle to contract and then recover, or the electrical impulse to fire impulses and then recharge. When the QT interval is longer than normal, it increases the risk for torsade de pointes, a life-threatening form of ventricular tachycardia.(Get more information about Long QT Syndrome)


These are slow heart rhythms, which may arise from disease in the heart’s conduction system (such as SA node, AV node or HIS-Purkinje system).

Sinus node dysfunction

A slow heart rhythm due to an abnormal SA (sinus) node.

Heart block

A delay or complete block of the electrical impulse as it travels from the sinus node to the ventricles. The level of the block or delay may occur in the AV node or HIS-Purkinje system. The heart may beat irregularly and, often, more slowly.

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