Medically Reviewed By William C. Lloyd III, MD, FACS
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What is defibrillation?

Defibrillation is an emergency treatment for ventricular fibrillation and other life-threatening arrhythmias (abnormal heartbeats). A heart in ventricular fibrillation stops pumping blood to the brain and body. It will cause cardiac arrest and death within a few minutes if not treated immediately. Defibrillation restores a normal heartbeat by shocking the heart with electricity.

Rapid defibrillation saves lies, especially when combined with CPR and intensive medical care. Defibrillation does not reverse the underlying cause of the arrhythmia. It is not successful in all cases, especially with serious, untreated heart disease or certain end-stage diseases.

Types of defibrillators

The types of defibrillators include:

  • Advanced life support (ALS) unit is a device used by healthcare providers in hospitals and ambulances. ALS units also provide vital information to help healthcare providers make decisions and deliver treatments.
  • Automatic external defibrillator (AED) is a user-friendly device that laypersons and emergency medical technicians (EMTs), can operate. AEDs are available in public places, such as schools, shopping malls, and airports. An AED guides users to apply electrodes. It then automatically analyzes the patient’s heart rhythm. AEDs tell users to deliver a shock, if needed, or will deliver the shock automatically.
  • Implantable cardioverter defibrillator (ICD) is implanted in the chest or belly. It is attached to the heart by wires and electrodes and will automatically deliver a shock when needed. Your doctor may recommend an ICD if you are at risk for a life-threatening ventricular arrhythmia.
  • Wearable defibrillator is worn outside the body. Your doctor may recommend this device if you have a short-term risk of a life-threatening arrhythmia, or if you are not a candidate for an implantable device.

Other procedures that may be performed

Defibrillation must be combined with intensive medical care, called advanced cardiac life support (ACLS). ACLS treats the underlying cause of life-threatening ventricular arrhythmias and prevents them from occurring again. ACLS includes:

  • CPR (cardiopulmonary resuscitation) and repeat defibrillation as needed
  • Continuous monitoring of vital signs, heart rhythm, and other functions
  • IV medications to suppress more arrhythmias, reduce the heart’s workload, and improve blood pressure, vital signs, and other functions 
  • Oxygen therapy, which is often combined with intubation (placing a breathing tube in the windpipe). The breathing tube is connected to a ventilator to assist or perform breathing for the patient. 
  • Pacing using a temporary pacemaker to correct arrhythmias

Other procedures vary depending on the underlying cause of the life-threatening ventricular arrhythmia. Common procedures include:

  • Coronary angioplasty to widen or open a blocked or narrowed coronary (heart) artery. Blocked or narrowed coronary arteries are a risk for a heart attack.
  • Permanent pacemaker implant to provide continuous or as-needed automatic pacing of the heart rhythm 

Why is defibrillation performed? 

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. 

Electrical signals coordinate the chambers to produce a normal heartbeat. Certain malfunctions in these signals will cause a disorganized, ineffective, quivering rhythm.

Defibrillation delivers an electrical shock that 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. Defibrillation must be done within several minutes of the start of a life-threatening ventricular arrhythmia to be effective.

Defibrillation treats immediately life-threatening ventricular arrhythmias including:

  • Ventricular fibrillation, which occurs when the lower chambers of your heart, or ventricles, beat so fast and unevenly that they just quiver, or shake. As a result, your heart pumps very little or no blood to your brain and body. Death occurs within five to 10 minutes without defibrillation.

  • Ventricular tachycardia without a pulse, which occurs when the ventricles beat extremely fast. This decreases efficiency of the heart. It reduces the amount of blood that your heart can pump out to your brain and body. If the amount of blood is not enough to produce a pulse or causes you to pass out, it requires treatment with defibrillation. Ventricular tachycardia without a pulse can also rapidly lead to ventricular fibrillation.

Ventricular fibrillation and ventricular tachycardia without a pulse can be due to:

  • Drug toxicity including overdose, poisoning, or adverse effects from cocaine, methamphetamine, digoxin (Lanoxin), tricyclic antidepressants, certain antiarrhythmic drugs, certain antipsychotics, and venlafaxine (Effexor). Certain chemical exposures, including benzene and vinyl chloride, can also cause life-threatening heart arrhythmias.

  • Electrolyte imbalance including abnormal amounts of potassium, calcium or magnesium in the bloodstream

  • Heart disease including heart attack, other cardiac arrhythmias, certain congenital heart defects (birth defects), cardiomyopathy, congestive heart failure, and previous cardiac arrest

Who performs defibrillation?

A doctor or specially trained nurse, paramedic, or other healthcare provider performs defibrillation. A layperson might perform defibrillation in a public place where an automatic external defibrillator (AED) is available. Some people at risk for life-threatening ventricular arrhythmias have an implantable cardioverter defibrillator (ICD) inside their body. An ICD will automatically perform defibrillation when needed. 

Doctors who perform defibrillation include: 

  • Cardiologists specialize in the medical treatment of heart diseases.

  • Critical care medicine doctors specialize in the diagnosis and management of life threatening conditions.

  • Emergency medicine doctors and pediatric emergency medicine doctors specialize in rapidly diagnosing and treating acute or sudden illnesses and injuries, and complications of chronic diseases.

  • Cardiac surgeons specialize in the surgical treatment of conditions of the heart and its blood vessels. Cardiac surgeons may also be known as cardiothoracic surgeons.

  • Thoracic surgeons specialize in the surgical treatment of diseases of the chest, including the blood vessels, heart, lungs and esophagus. Thoracic surgeons may also be known as cardiothoracic surgeons.

How is defibrillation performed?

The defibrillation procedure varies depending on the type of device. It generally includes these steps:

  1. The provider will start CPR until a heart defibrillator is available.

  2. The provider will apply two sticky defibrillator electrodes or paddles lubricated with special jelly to your upper right chest and lower left ribcage area. An alternate position is the upper right chest and the upper left back. In rare cases, a doctor will make an incision into your chest (thoracotomy) and place the electrodes directly on your heart muscle.

  3. The provider or the AED will analyze your heart rhythm and deliver a shock to your heart if needed.

  4. The provider or the AED will re-analyze the resulting heart rhythm and provide more shocks as needed. During this time, a team of healthcare providers will continue CPR and advanced life support (ALS) treatments as needed.

An implantable cardioverter defibrillator (ICD) will automatically perform defibrillation as needed. A defibrillation shock from an ICD feels like being kicked in the chest. If you receive a defibrillation shock from your ICD, you or someone you are with should immediately call 911, even if you feel fine. You will need evaluation and may need more treatment.

Will I feel pain?

Your comfort and relaxation is important to you and your care team. Defibrillation is a traumatic procedure. People often compare the shock to being kicked in the chest. You will likely be unconscious and unaware during defibrillation and unaware of the procedure. Sometimes people who are defibrillated regain consciousness very rapidly and feel some chest pain or discomfort. 

Near-death experiences, such a life-threatening heart arrhythmia and defibrillation, are emotionally traumatic and may cause a lot of anxiety when you regain consciousness. You will have enough sedation and pain medications so that you are comfortable. Tell your care team if you are uncomfortable in any way.

What are the risks and potential complications of defibrillation?  

There are risks and potential complications with defibrillation. The life-saving benefit of defibrillation far outweighs the risks. Risks and potential complications include:

  • Skin burns

  • Myocardial necrosis (death of heart muscle tissue)

  • Other cardiac arrhythmias including asystole (no heart rhythm, or “flatline”), ventricular fibrillation after pulseless ventricular tachycardia, and other less serious arrhythmias

Reducing your risk of complications

Defibrillation is an emergency procedure, so it is not possible to prevent or reduce all risks and potential complications. However, defibrillation saves lives and there are things you can do after defibrillation to reduce further risks. This includes:

  • Following activity, dietary and lifestyle restrictions and recommendations during and after recovery

  • Calling 911 immediately if you have chest pain or discomfort, chest pressure, racing heartbeat, sensation of fluttering in your chest, shortness of breath, dizziness, or passing out

  • Taking your medications exactly as directed

  • Telling all members of your care team if you have any allergies

What can I expect after defibrillation?

Knowing what to expect can help make your road to recovery after defibrillation as smooth as possible. 

How long will it take to recover?

You will need close monitoring in a critical care setting in a hospital after defibrillation. You will also need other treatments to stabilize your condition and treat the underlying cause of your arrhythmia. 

Recovery time varies depending on the underlying cause, your general health, your age, and other factors. Ask your doctor about all the factors that influence your recovery and when you can return to normal activities.

How will I feel after defibrillation?

It is common for people who have survived a near-death experience to be upset and experience many emotions, including anxiety and fear. Some people find it helpful to talk to a pastor, therapist, or other professional support person. 

You will also likely feel fatigued and may have chest soreness and pain from skin burns after defibrillation. Your care team will treat your pain as needed. Ask your doctor before taking any pain medication at home and only take pain medication as directed.

Contact your doctor if your pain is not well controlled by your medication or you have new or worsening pain, fatigue, or other symptoms.

When should I call my doctor?

It is important to keep your follow-up appointments after defibrillation. Contact your doctor for questions and concerns between appointments. Seek immediate medical care (call 911) if you have:

How might defibrillation affect my everyday life?

Defibrillation can save your life, but it will not cure heart disease or other underlying causes of life-threatening ventricular arrhythmias. You may need to make adjustments in your diet and lifestyle as part of your treatment plan after defibrillation. These will vary depending on the underlying cause, your general health, your age, and other factors. 

Talk with your doctor about your diagnosis and treatment plan and how it will affect your everyday life.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Nov 15
View All Heart Health Articles
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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