An arrhythmia is an abnormal rhythm of the heart that can cause the heart to pump less effectively.

Atrial fibrillation is a type of arrhythmia in which the electrical signals in the atria, or the two small chambers of the heart, are fired in a very fast and uncontrolled manner.

Did you know that electrical currents flow throughout your body? Because the strongest of these travels through your heart, doctors are able to monitor your heart by placing electrical sensors on the surface of your skin. They do this by giving you an electrocardiogram -- abbreviated either ECG or EKG (from the original German spelling of the word).

A pacemaker is a small device implanted under the skin that sends electrical signals to start or regulate a slow heartbeat.

With advances in technology, pacemakers and ICDs generally last several years and, in most cases, allow a person to lead a normal life.

Do cell phones interfere with pacemakers? Do ICDs need to be adjusted? Here are answers to these and other questions.