How do Doctors Use Cardioversion for Atrial Fibrillation?

Cardioversion for atrial fibrillation is a medical procedure that physicians use to get the heart, specifically the left atrium of the heart, to beat normally. A complex reaction involving electricity is what causes the heart to beat. When those electric signals are delivered incorrectly to the heart, it can quiver instead of beat. This irregular heartbeat can have serious consequences for a patient. By delivering a controlled shock — cardioversion — to the heart, physicians can usually restore the heart beat to a normal sinus rhythm, or normal heart beat, instead of a quiver.

Knowing just a little about cardiac anatomy is helpful in understanding the use of cardioversion for atrial fibrillation. Think of the heart as a circle divided into four equal pieces, and each piece is a chamber. The upper left chamber is called the left atrium. Freshly oxygenated blood from the lungs comes into the left atrium, and is pumped through the next chamber, the left ventricle, which sits directly below the left atrium. From there the blood is pumped into the rest of the body.

If the left atrium quivers instead of beats, blood is not pumped well to the rest of the body causing dizziness and weakness. This is atrial fibrillation. When blood doesn’t move from the quivering left atrium, it tends to clot. When the left atrium starts to beat correctly again, this clot can be pumped into the brain and cause a stroke. To prevent this, physicians want to get the heart beating normally as soon as possible; to do so, they use electrical cardioversion.

In cardioversion for atrial fibrillation, most physicians will use medication to anesthetize the patient, because the procedure is uncomfortable. An electrocardiograph (ECG or EKG) is used to monitor the heart, and blood pressure and breathing are also monitored. The physician may use a transesophegeal echocardiogram (TEE), an ultrasound of the heart, to see if any blood clots have formed. Many patients are put on an anti-clotting medication as soon as atrial fibrillation is detected to prevent clots from forming.

Cardioversion for atrial fibrillation is done in a hospital setting, in case of any complications. The physician, often a cardiologist, uses patches or paddles applied directly to the chest to send an electric current to the heart. Two or three shocks are sometimes needed to get the heart rhythm back to normal. After the rhythm is back to normal, a patient is monitored until the medication given begins to wear off. The patient's heart is continuously monitored during this recovery period to make sure the rhythm remains normal.

In 90 percent of cases, cardioversion is successful in restoring a normal sinus rhythm. Many patients will experience repeated episodes of atrial fibrillation and may need cardioversion multiple times. Medication or a pacemaker also may be needed to help control atrial fibrillation.