Cardioversion

External cardioversion

An external cardioversion is often performed in an emergency situation. When a person's heart is beating abnormally and inadequately pumping blood to the body, an electrical shock is given with a defibrillator to revert the heart rate to a normal rhythm.

Other times, an external cardioversion is scheduled ahead of time to treat an arrhythmia (most often atrial fibrillation) that is recent or has not responded well to medication. Prior to the scheduled cardioversion, it is often necessary to run tests to make sure that there are no blood clots in the heart. Some people need medication to "thin" their blood before having the cardioversion.

For a scheduled cardioversion, the person is usually sedated beforehand and his or her breathing is assisted. The doctor then delivers an electrical shock from a defibrillator to the heart using paddles on the patient's chest. The electrical shock usually makes the person's heart convert back to a normal rhythm. Afterwards, to decrease the likelihood of the arrhythmia returning -- or to prevent blood clots from entering the general circulation -- the doctor may recommend a medication regimen.