Arrhythmia

Abnormal Heart Rhythms

An abnormal heart rhythm is a change in the speed or pattern of the heartbeat -- the heart may beat too slowly, too rapidly or irregularly. When the heart beats too slowly, too little blood is pumped out to the rest of the body. When the heart beats too quickly, it cannot fill completely with blood so the body doesn't receive the blood volume it needs to function properly. Slow heart rates are called bradycardias. Fast heart rates are called tachycardias.

The heart is made up of four chambers. The upper chambers, called the atriums, receive and collect blood. The lower chambers, called the ventricles, pump blood to the body. Working together, the chambers of the heart move life-sustaining blood throughout the body. Please see Normal Hearts to learn more about how the heart works.

There are several types of abnormal heart rhythms, some occur in one of the atriums and are called atrial, others occur in the ventricles and are called ventricular. Click on the links below for more information about these abnormal heart rhythms including animated diagrams:

• Atrial Flutter
• Atrial Fibrillation
• Atrial Tachycardia
• Supraventricular Tachycardia
• Wolff-Parkinson-White Syndrome
• Complete Heart Block
• Ventricular Tachycardia
• Ventricular Fibrillation

To learn more about abnormal heart rhythms, visit:

• Signs and Symptoms
• Diagnosis
• Treatment

Reviewed by health care specialists at UCSF Medical Center.
Last updated May 8, 2007

This information is for educational purposes only and is not intended to replace the advice of your doctor or health care provider. We encourage you to discuss with your doctor any questions or concerns you may have.