Patient education: Cardioversion (The Basics)

What is cardioversion? — 

This is a treatment to fix abnormal heart rhythms.

Everyone has a built-in electrical system in their heart that controls their heartbeat (figure 1). Electrical signals in the heart control which parts of the heart pump and when. Sometimes, these signals become abnormal and cause an abnormal heart rhythm, called an "arrythmia."

Some types of abnormal heart rhythms that might be treated with cardioversion include:

●Atrial flutter

●Atrial fibrillation

●Supraventricular tachycardia

●Ventricular tachycardia

Abnormal heart rhythms can lead to problems like heart failure, stroke, and even death. This is why getting treatment is so important.

Cardioversion can be done in 2 ways:

●Electrical cardioversion – The doctor sends an electric shock through your heart. After the shock, your heart might begin beating normally again.

●Drug cardioversion – You get medicines to try to reset your heart's rhythm. Sometimes, doctors will try this before doing electrical cardioversion.

How do I prepare for cardioversion? — 

The doctor or nurse will tell you if you need to do anything special to prepare. You might need to take medicines called "anticoagulants" or "blood thinners." These do not actually thin the blood. They just make the blood less likely to form clots.

Before the procedure, your doctor will do an exam. They might order tests, such as:

●Electrocardiogram ("ECG") – This records your heart rate and rhythm by measuring the electrical activity in your heart (figure 2).

●Transesophageal echocardiogram ("TEE") – Your doctor inserts a thick probe called a "transducer" through your mouth and into your esophagus. (The esophagus is the tube that carries food from your mouth to your stomach.) The transducer sends sound waves toward your heart, and the sound waves create images of the inside of your heart. If the TEE shows any blood clots in your heart, your doctor will usually delay your cardioversion until a later time.

Your doctor will also ask about your "health history." This involves asking about any health problems you have or had in the past, past surgeries, and any medicines you take. Tell them about:

●Any medicines you are taking – This includes prescription and "over-the-counter" medicines, plus any herbal supplements. It helps to write down and bring a list of your medicines, or bring a bag with all your medicines with you.

●Any allergies you have

●Any bleeding problems you have – Certain medicines, including some herbs and supplements, can increase the risk of bleeding. Some health conditions also increase this risk.

You will also get information about:

●Fasting – This means not eating or drinking anything for a period of time. Whether you need to fast, and for how long, depends on the procedure.

●What help you will need when you go home – For example, you might need someone else to bring you home or stay with you for some time while you recover.

Ask the doctor or nurse if you have questions or if there is anything you do not understand.

What happens during cardioversion? — 

When it is time for the procedure:

●You will get an "IV," which is a thin tube that goes into a vein. This can be used to give you fluids and medicines.

●The doctors and nurses will monitor your breathing, blood pressure, and heart rate during the procedure.

●The doctor will attach small, sticky patches called "electrodes" to your chest. These will monitor the electrical activity in your heart during the procedure.

●For electrical cardioversion:

•You will get "sedative" medicines. These make you relax and feel sleepy. You might be awake for some parts of the procedure, but you might not remember it.

•The doctor will attach 2 larger "defibrillator pads" to your skin. These go on your chest or, sometimes, your chest and back. The pads are connected to a machine called a "defibrillator," which gives the electric shock.

•The doctor will use the defibrillator to give a shock. Then, they will monitor your heart rate. If the shock works properly, it will cause your heart to start beating normally. Sometimes, the doctor might need to try more than 1 shock to reset your heart's rhythm.

●For drug cardioversion:

•The doctor will give you medicines, either by mouth or through an IV. If the medicine works properly, it will cause your heart to start beating normally.

•Sometimes, the doctor might need to give you more than 1 dose of the medicine to reset your heart's rhythm.

What happens after cardioversion? — 

You will be taken to a recovery room. If you had sedatives, the staff will watch you closely as they wear off. You might feel tired for a short time.

Usually, you can go home the same day. But in some cases, you might need to stay in the hospital for longer.

What are the risks of cardioversion? — 

Your doctor will talk to you about all the possible risks, and answer your questions. Possible risks include:

●Your abnormal heart rhythm isn't fixed, or you have another heart rhythm problem.

●Blood clots – If a blood clot blocks a blood vessel, this can cause problems. Sometimes, electrical cardioversion can dislodge blood clots from the heart and send them to other parts of the body.

●Minor burns, pain, or skin irritation – This can happen where the defibrillator pads or electrodes were attached.

●Low blood pressure – Usually, this is caused by the sedative medicines and goes away after a few hours.

What if I am pregnant? — 

Cardioversion can be done during pregnancy. It does not affect your baby's heart rhythm. But your doctor will probably monitor your baby's heart during the procedure.

What else should I know? — 

Ask your doctor about any lifestyle changes you should make to keep your heart healthy.

If you have any signs of a stroke after having cardioversion, call for an ambulance right away (in the US and Canada, call 9-1-1).

More on this topic

Patient education: Cardioversion – Discharge instructions (The Basics)
Patient education: Overview of heart arrhythmias (The Basics)
Patient education: Atrial flutter (The Basics)
Patient education: Atrial fibrillation (The Basics)
Patient education: Heart failure and atrial fibrillation (The Basics)
Patient education: Supraventricular tachycardia (SVT) (The Basics)
Patient education: Ventricular tachycardia (The Basics)
Patient education: Wolff-Parkinson-White syndrome (The Basics)
Patient education: Long QT syndrome (The Basics)

Patient education: Cardioversion (Beyond the Basics)
Patient education: Atrial fibrillation (Beyond the Basics)
Patient education: Wolff-Parkinson-White syndrome (Beyond the Basics)