Cardioversion is a method to return an abnormal heart rhythm back to normal.
Cardioversion can be done using an electric shock or drugs.
Electric cardioversion may be done with a device that gives off a shock. The device can be placed inside (internal) or the shock can be delivered from the outside (external) the body.
External electric cardioversion uses a device called a defibrillator.
Electrode patches are placed on the chest and back. The patches are connected to the defibrillator.
The defibrillator is activated and an electric shock is delivered to your heart.
This shock briefly stops all electrical activity of the heart. Then it allows the normal heart rhythm to return.
Sometimes more than one shock, or a shock with higher energy is needed.
Emergency external electric cardioversion is used to treat abnormal heart rhythms (arrhythmia) that can cause death, such as ventricular tachycardia or ventricular fibrillation.
External electric cardioversion may also be used for non-emergency conditions. Heart rhythm problems, such as atrial fibrillation or paroxysmal supraventricular tachycardia (PSVT) that began recently or that cannot be controlled with medicines may be treated this way.
You may need tests before having external cardioversion to make sure that there are no blood clots in the heart.
Some people may need to take blood thinners.
You may be given medicine to help you relax before the procedure.
After the procedure, you may be given medicines to prevent blood clots and to help prevent the arrhythmia from coming back.
An implantable cardioverter-defibrillator (ICD) is a device that is placed inside your body. It is most often used in people who are at risk for sudden death from ventricular tachycardia or ventricular fibrillation, or who have had these heart rhythms before.
The ICD is implanted underneath the skin of your upper chest or abdomen.
Wires are attached that go into the heart.
If the device detects a dangerous heartbeat, it sends an electrical shock to the heart to change the rhythm back to normal.
CARDIOVERSION USING DRUGS (PHARMACOLOGIC)
Cardioversion can be done using drugs that are taken by mouth or given through an intravenous line (IV). It can take from several minutes to days for this treatment to work. If you are given drugs for cardioversion in a hospital, your heart rate will be regularly checked.
Cardioversion using drugs can be done outside the hospital. This treatment is most often used for people with atrial fibrillation that comes and goes. However, you will need to be closely followed-up by a cardiologist.
As with electrical cardioversion, you may be given blood thinning medicines to prevent blood clots from forming and leaving the heart (which can cause a stroke).
Complications of cardioversion are uncommon, but may include:
Allergic reactions from medicines used
Blood clots that can cause a stroke or other organ damage
Bruising, burning, or pain where the electrodes were used
Worsening of the arrhythmia
People who perform external cardioversion may be shocked if the procedure is not done correctly. This can cause heart rhythm problems, pain, and even death.
Epstein AE, DiMarco JP, Ellenbogen KA, et al. 2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2013 Jan 22;61(3):e6-75.
Lafuente-Lafuente C, Mah I, Extramiana F. Management of atrial fibrillation. BMJ. 2009; 339:b5216. doi: 10.1136/bjm.b5216.
Miller JM, Zipes DP. Therapy for cardiac arrhythmias. In: Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 37.
Myerburg RJ, Castellanos A. Approach to cardiac arrest and life-threatening arrhythmias. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 63.
Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.