What is cardioversion?

Cardioversion is a medical procedure used to restore your heartbeat to normal.

Why is cardioversion done?

Cardioversion is usually needed because the heart is beating abnormally. This abnormal heart beat, called an arrhythmia, can prevent your heat from pumping enough blood to your body. Some people who have an arrhythmia don’t notice any symptoms, while others may feel palpitations (very fast or irregular heart beat), short of breath, and very tired.

Your doctor may have already tried to treat your abnormal heart beat using medication. If this has not worked, cardioversion may successfully restore your heart beat to normal.

How is cardioversion done?

Cardioversion is done in a hospital or clinic. An intravenous (IV) catheter will be placed in a vein in your arm so that you can be given. Sedation will make you feel sleepy so you don’t feel any discomfort or pain during the procedure.

Your doctor will deliver an electrical shock through two adhesive pads placed onto your chest. The shock lasts less than one second, and briefly stops your heart so it can be reset and return to a normal heart beat. Some people need only one shock to revert back to a normal heart beat, while others need more.

The procedure takes about 30 minutes. Most of this time is used to make you sleepy and wake you up again, and many people don’t remember the procedure at all. It is likely that you will be able to go home on the same day as your cardioversion.

What are the risks?

If you have an irregular heartbeat, blood clots can form within your heart. Cardioversion can cause a clot to dislodge (break free) and travel to your brain, resulting in a stroke. To avoid this happening, your doctor may give you medication called warfarin for two or three weeks before cardioversion, to thin your blood and make it less likely to clot.

Another risk of cardioversion is that the skin on your chest where the adhesive pads were placed may become irritated. This is easily treated by application of a cream.

Cardioversion may not restore a normal heart beat. If this happens, you may need a different type of treatment, such as medication, a pacemaker, or an implantable cardioverter defibrillator. Your doctor will discuss these treatment options with you.

Publication details

Version 1.1 Published April 2016. Next review 2023.


The information on this page is general in nature and cannot reflect individual patient variation. It reflects Australian intensive care practice, which may differ from that in other countries. It is intended as a supplement to the more specific information provided by the doctors and nurses caring for your loved one. ICNSW attests to the accuracy of the information contained here but takes no responsibility for how it may apply to an individual patient. Please refer to the full disclaimer.