What is cardioversion?

Cardioversion is a treatment for cardiac arrhythmias (abnormal heartbeats), including atrial fibrillation. Arrhythmias happen when the heart’s electrical signal causes it to pump too fast or irregularly. Arrhythmias can prevent the heart from pumping enough blood to your brain and body and cause other problems, such as blood clots. Cardioversion uses medications or low-energy electrical shocks to restore a normal heartbeat.

Cardioversion is usually a scheduled procedure. It is an emergency procedure done right away when symptoms are severe. Severe symptoms include dizziness, passing out, chest pain, shortness of breath, and low blood pressure.  

Cardioversion is only one method of treating cardiac arrhythmias. Discuss all of your treatment options with your doctor to understand which choices are right for you. 

Types of cardioversion

There are two basic methods of performing cardioversion. Your doctor will chose the best method for you based on the type of rhythm, your medical history, and your particular situation. Types of cardioversion include:

  • Chemical or pharmacological cardioversion uses oral or IV medications to convert your arrhythmia to a normal heartbeat. You may take medications at home or stay in the hospital during chemical cardioversion. Your doctor will monitor you closely in either case. 
  • Electrical cardioversion uses low-energy shocks to convert your arrhythmia to a normal heartbeat. Electric cardioversion delivers an electrical shock at a specific time in the heart rhythm. Electric cardioversion causes all the heart cells to contract at the same time. This stops the abnormal rhythm and allows the heart to restart normal electrical activity.

Patients with a high risk of arrhythmias that can become rapidly life threatening may have an implantable cardioverter defibrillator (ICD). An ICD is implanted in the chest or belly. It is attached to the heart by wires and electrodes. 

An ICD delivers low-energy cardioversion shocks automatically when needed. If cardioversion shocks don’t convert the arrhythmia, the ICD will deliver a higher-energy defibrillation shock to convert the arrhythmia.

Other procedures that may be performed 

Your doctor may perform other procedures to diagnose and treat your cardiac arrhythmia or the underlying cause. Other procedures include: 

  • Advanced cardiac life support (ACLS) to stabilize your condition as needed. This can include defibrillation, cardiopulmonary resuscitation (CPR), and continuous monitoring of your vital signs and heart rhythm. ACLS may also include IV medications, oxygen therapy, and placing a breathing tube in your windpipe (intubation) and attaching it to a ventilator.
  • Transesophageal echocardiography (TEE) to rule out blood clots in the heart before your scheduled cardioversion. The arrhythmia, atrial fibrillation, can cause blood clots to develop in the heart. If you have blood clots, you may need to take blood-thinning medicines before a scheduled cardioversion.

Why is cardioversion performed? 

Your doctor may recommend cardioversion to treat cardiac arrhythmias when medications are not successful or when the rhythm causes serious symptoms. Serious symptoms include shortness of breath, dizziness, passing out, low blood pressure, and chest pain or pressure. 

Your heart is a muscle that works like a pump. It has four chambers, two upper chambers (atria) and two lower chambers (ventricles). Like all pumps, your heart requires an energy source to function. 

Your heart's energy comes from a built-in electrical conduction system that sends electrical signals through the four chambers. These electrical signals coordinate the chambers to produce a normal heartbeat. Certain malfunctions in these signals will cause an arrhythmia that may require cardioversion.

Cardioversion treats the following cardiac arrhythmias:

  • Atrial fibrillation, which occurs when electrical signals move too fast and erratically through the heart’s upper chambers (atria). This causes the atria to quiver instead of contracting effectively.
  • Atrial flutter, which occurs when electrical signals move regularly, but too fast, through the atria.
  • Ventricular tachycardia with a pulse, which occurs when the ventricles beat extremely fast. The rapid contractions cannot pump enough blood to produce a pulse for very long. Without rapid cardioversion, it can quickly lead to ventricular fibrillation. This is a life threatening cardiac arrhythmia that can lead to cardiac arrest and death.