A cardioversion is a nonsurgical procedure that delivers a small dose of electricity to the heart at a specific time in the cardiac cycle in hopes of changing, or converting, an irregular heart rhythm to a normal, regular rhythm.

The heart is a muscular organ about the size of a closed fist. It pumps oxygen-rich blood to the body. The heart requires an electrical impulse or signal from the heart’s internal electrical system (or conduction system) to produce a heartbeat. The electrical impulse starts in the atria, or upper chambers of the heart, and travels down to the ventricles, or lower chambers of the heart, causing the heart to contract and pump blood throughout the body.

Heart rhythm disorder can result from a variety of causes, including underlying heart disease (such as coronary artery disease, heart valve disease or heart failure), thyroid dysfunction or an electrolyte abnormality (e.g., a potassium, magnesium or calcium imbalance). Heart rhythm disorders may occur without underlying heart disease and be caused by stimulants such as caffeine, emotional stress, prescribed as well as illicit drugs, or physical activity.

Atrial fibrillation is one example of an irregular heart rhythm. Some people with atrial fibrillation have no symptoms. Others may feel palpitations, shortness of breath, weakness or fatigue. Your physician may first use medicines to change your atrial fibrillation to a regular rhythm. If medication doesn't work, an electrical cardioversion may be needed.