The heart beats 60-100 times a minute to continuously pump blood throughout the body. This regular contraction is controlled by a natural pacemaker called the sinoatrial node (SA Node) located in the upper portion of the right atrium of the heart. The electrical current is initiated here, and spreads to the atrioventricular node (AV Node), and then to the bundle branches and purkinje fibers, thus initiating the coordinated pumping action of the heart.

A disturbance in the regular rhythm of the heart is called an arrhythmia. Arrhythmias are caused by an interruption in the normal pathway of electrical conduction through the heart. This "short" in the electrical circuit disrupts the natural pacemaker and therefore the heartbeat.

There are, many different types of arrhythmias. Some arrhythmias cause the heart to beat too slow and some cause it to beat too fast. These irregular heartbeats may be detected on an electrocardiogram (EKG).

At times they can be felt as skipped beats or palpitations. Many people have heart rhythm irregularities (arrhythmias) that never require medical treatment or medication. Other people may require medication or a pacemaker to control the irregular heartbeats.

There may be times when an arrhythmia is severe enough to affect the ability of the heart to pump. If the heart cannot pump adequately, blood pressure and the circulation of blood and oxygen cannot be maintained. This type of arrhythmia is dangerous and known as a life-threatening arrhythmia. Fainting spells, blackouts, dizziness, loss of consciousness and cardiac arrest may be associated with this arrhythmia. Usually, medication can control these arrhythmias and their associated symptoms. When medication is unable to do so, a cardiac operation may be necessary to treat the rhythm disturbance. There are many types of cardiac arrhythmia operations. Your cardiologist and surgeon will discuss in detail with you the type of arrhythmia operation you require.

Acknowledgements
Content: Jaelene K. Williams, RN, MS
Medical Illustrations: Kathleen Wagner
Illustrations: Catherine Gendron