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Electrical cardioversion – the rhythm reset

Electrical cardioversion is a procedure in which a patient receives an electrical shock on the outside of the chest (while under mild anesthesia) using either paddles or patches. The shock can be used to “reset” the heart to a normal rhythm. The procedure is similar to defibrillation but uses much lower levels of electricity. Defibrillation delivers a stronger shock than electrical cardioversion. It’s often used during a sudden cardiac arrest to quickly restore normal heart rhythm.

The decision to use electrical cardioversion

Your health care professional may recommend a transesophageal echocardiography (TEE) as a first step. The TEE procedure involves swallowing a small ultrasound device that allows the health care team to view the inside your heart atria for blood clots.

If you already have clots in the atria, you will need protection from increasing your stroke risk. So your health care professional may recommend a *blood thinner before an electrical cardioversion procedure. Electrical cardioversion often successfully restores a regular heart rhythm. But atrial fibrillation, also called AFib, may return. In many instances, you may need anti-arrhythmia medications indefinitely to keep your heart’s rhythm and rate in the best range. Your health care professional may give you medication to restore your heart’s normal rhythm and then monitor your heart for a few hours in a hospital setting. This is called pharmacological cardioversion.

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Radiofrequency ablation or catheter ablation

Ablation is a procedure for cardiac arrhythmias if long-term medications or electrical cardioversion are not preferred or were not effective. Before ablation surgery, doctors perform electrical mapping of the heart using an electrically sensitive catheter to map the origins of “extra” electrical activity throughout the heart. The map tells the doctor which areas of the heart are creating problematic electric signals that interfere with the proper rhythm.

How is an ablation performed?

A catheter is inserted into a blood vessels and gently guided to the heart. The doctor carefully destroys malfunctioning tissue using the catheter to deliver energy (such as radiofrequency, laser or cryotherapy) to scar the problematic areas. The scarred areas will no longer send abnormal signals.

If successful, the heart will return to a normal rhythm. AFib may return, so multiple ablation procedures may be needed. This minimally invasive procedure usually has a short recovery period. Patients are generally placed on a short course of anti-arrhythmic drugs while the procedure takes full effect.

Common types of ablation for AF include:

• Pulmonary vein isolation ablation (PVI ablation or PVA). In some AFib patients, fibrillation is triggered by extra electrical currents in the pulmonary veins. During this procedure, doctors use the catheter tip to destroy the tissue that is sending the extra currents. In most cases, a normal heart rhythm returns.
• AV node ablation with pacemakers. In other AFib patients, the trigger for their AFib occurs in the atrioventricular node (where the electrical signals pass from the atria to the ventricles). Doctors place the catheter near the AV node and destroy a small area of tissue. They then implant a pacemaker to restore and maintain the heart’s normal rhythm.

What is an echocardiogram? (PDF)
What are electrophysiology studies? (PDF)