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Electrical Cardioversion (Defibrillation) for a Fast Heart Rate
Electrical cardioversion is a procedure in which a brief electric shock is given to the heart to reset the heart rhythm back to its normal, regular pattern (normal sinus rhythm). The shock is given through patches applied to the outside of the chest wall. In some situations an external defibrillator, which has paddles, might be used.
Usually, the person is sedated. If the person is conscious, medicine is given to control pain and to cause the person to relax to the point of being nearly unconscious during the procedure.
What To Expect
After cardioversion, the person's heart rate and blood pressure are monitored.
Additional drugs to help prevent heart rhythm problems from recurring (antiarrhythmic drugs) may also be given before and after the procedure. If antiarrhythmic drugs are not used after cardioversion, the heart may be at greater risk of going back into a fast heart rate.
After cardioversion, you may take a blood-thinning medicine for a few weeks to prevent dangerous blood clots.
Why It Is Done
Cardioversion may be used as an emergency procedure to stop a fast heart rate that is causing low blood pressure or severe symptoms. These heart rate problems include atrial fibrillation, supraventricular tachycardia, and ventricular tachycardia.
How Well It Works
Electrical cardioversion of the heart is very effective. Most people who receive cardioversion return to normal sinus rhythm immediately after the procedure.footnote 1
Risks of the procedure include the following:
- A blood clot may become dislodged from the heart and cause a stroke. Your doctor will try to decrease this risk by using anticoagulants or other measures.
- The procedure may not work. Additional cardioversion or other treatment may be needed.
- Antiarrhythmic medicines used before and after cardioversion or even the cardioversion itself may cause a life-threatening irregular heartbeat.
- You can have a reaction to the sedative given before the procedure. Harmful reactions are rare.
- You can get a small area of burn on your skin where the paddles or patches are placed.
What To Think About
Cardioversion is only a temporary fix for a fast heart rate. Medicines (such as beta-blockers and calcium channel blockers or other antiarrhythmic medicines) may be used to keep the heart rate slow when a person has an episode of supraventricular tachycardia (SVT). For long-term treatment and to reduce the chance of having another episode of either SVT or ventricular tachycardia (VT), catheter ablation or medicine can be used.
- Page RL, et al. (2015). 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation. DOI: 10.1161/CIR.0000000000000311. Accessed September 23, 2015.
Current as of: December 15, 2019
Author: Healthwise Staff
Medical Review: Rakesh K. Pai, MD - Cardiology, Electrophysiology
E. Gregory Thompson, MD - Internal Medicine
Martin J. Gabica, MD - Family Medicine
Adam Husney, MD - Family Medicine
John M. Miller, MD, FACC - Cardiology, Electrophysiology
Current as of: December 15, 2019
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