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Cardioversion

Definition

Cardioversion is a method to restore an abnormal heart rhythm back to normal.

Information

Cardioversion can be done using an electric shock or medications.

ELECTRIC CARDIOVERSION

Electric cardioversion may use a device that can be placed inside (internal) or outside (external) the body.

External electric cardioversion uses a device called a defibrillator.

• Electrode patches are placed on the front and back of the chest and connected to the defibrillator.
• After the defibrillator paddles (or large patches) are placed on your chest, 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 any abnormal heart rhythm (arrhythmia) that is life threatening, such as ventricular tachycardia or ventricular fibrillation. Such a shock can be life saving.

External electric cardioversion may also be used when there is not an emergency.

• 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.
• First, tests are often done to make sure that there are no blood clots in the heart.
• Some people may need to take blood thinners before the cardioversion procedure.
• You will usually be given a sedative before the procedure starts.
• After the external cardioversion, you may be given medicine to prevent blood clots and to help prevent the arrhythmia from coming back.

An implantable cardioverter-defibrillator (ICD) is a device that is usually placed underneath the skin of your upper chest or abdomen. Wires are attached that go into the heart.

• The ICD detects life-threatening, rapid heartbeats. If such a heartbeat (arrhythmia) occurs, the ICD quickly sends an electrical shock to the heart to change the rhythm back to normal.
• An ICD is most often placed in people who are at high risk of sudden death from dangerous arrhythmias, such as ventricular tachycardia or ventricular fibrillation. Often, they are placed in people who have had these dangerous abnormal heart rhythms before.

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 several minutes to days for a 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, most often 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

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.

References

Epstein AE, DiMarco JP, Ellenbogen KA, et al. ACC/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices): developed in collaboration with the American Association for Thoracic Surgery and Society of Thoracic Surgeons. Circulation. 2008;117:e350-e408.

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: Saunders Elsevier; 2011:chap 37.

Morady F. Electrophysiologic interventional procedures and surgery. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 66.

Myerburg RJ, Castellanos A. Approach to cardiac arrest and life-threatening arrhythmias. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 63.

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