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Conditions InDepth: Arrhythmias (Heart Rhythm Disturbances)
- Two upper chambers (atria/atrium) —Receive blood from the body and empty the blood to the lower chambers.
- Two lower chambers (ventricles) —Receive blood from the upper chambers and pump blood to the lungs or out to the body. The left ventricle is the strongest muscle/chamber in the heart and is responsible for pumping the blood to the entire body.
- An electrical signal begins in a nerve bundle, in the atria, called the sinoatrial (SA) node. The SA node, also known as the pacemaker of the heart, stimulates the heart to beat at 60-100 times per minute.
- The SA node sends electrical signals to the muscles of the atria which makes them contract. At the same time, the SA node sends the signal down the heart through a nerve pathway.
- The signal travels from the SA node to the atrioventricular (AV) node, which sits between the ventricles and the atria. The signal slows here so that the ventricles have time to fill.
- The AV node then sends signals to the muscles of the ventricles to make them contract.
|Heartbeat: Anatomy of the Heart|
|The electrical signal starts in the sinoatrial (SA) node in the right atrium.|
|Copyright © Nucleus Medical Media, Inc.|
- Bradycardia —Heartbeat less that 60 beats per minute.
- Tachycardia —Heartbeat more than 100 beats per minute. Temporary tachycardia is a normal reaction to physical activity to help supply more oxygen to working muscles. Tachycardia that is not in response to physical activity can cause problems or be a sign of problems.
- Extra beats
- Skipped beats
- Reviewer: EBSCO Medical Review Board Michael J. Fucci, DO, FACC
- Review Date: 06/2017
- Update Date: 12/20/2014