A defibrillator is a life-saving device that delivers an electric shock to the heart in order to restore a normal rhythm when faced with potentially deadly abnormal heart rhythms like ventricular tachycardia (without a pulse) or ventricular fibrillation, both occurring in the heart’s lower chambers. This intervention can be critical during cardiac arrest, effectively halting the abnormal rhythm and allowing the heart to return to its regular beat. Nevertheless, it’s important to note that despite defibrillation, many individuals do not survive cardiac arrest, and those who do often require various forms of therapy for their recovery.


The sensation of receiving a shock from a personal defibrillator can vary from being painless to feeling like a forceful impact to the chest.

For individuals at high risk of experiencing life-threatening heart rhythms, there are two main types of defibrillators available:

  • Wearable cardioverter defibrillator (WCD): This device is worn like a vest discreetly under your clothing. It features sensors that make direct contact with your skin and can administer a shock when it detects an abnormal heart rhythm.
  • Implantable cardioverter defibrillator (ICD): Similar to a pacemaker, an ICD serves as an internal guardian against arrhythmias. It has the capability to deliver precisely measured electrical charges when necessary. In addition to maintaining a regular heartbeat, an ICD can also deliver a life-saving shock to the heart when it detects a potentially fatal rhythm.

Reasons for undergoing the procedure

For individuals with certain arrhythmias, immediate assistance can be obtained in a hospital or any location equipped with an automated external defibrillator. However, those at a high risk of life-threatening heart rhythm disturbances may require a personal defibrillator that they carry at all times. While cardiopulmonary resuscitation (CPR) can offer temporary aid, a defibrillator plays a crucial role in increasing survival chances during sudden cardiac arrest, even for individuals with existing pacemakers or implantable cardioverter defibrillators (ICDs).


A defibrillator should only be utilized in cases of ventricular tachycardia (without a pulse) or ventricular fibrillation. Employing it for any other type of arrhythmia could potentially induce ventricular fibrillation and lead to cardiac arrest.


Continuing CPR is crucial while waiting for a defibrillator to be prepared for use. Here’s what to do when using a defibrillator:

  • Ensure safety: Before delivering a shock, confirm that no one is in direct contact with the person in need of defibrillation or their bed.
  • Use an automated external defibrillator (AED): If you have access to an AED, it can assess the heart’s rhythm and determine if a shock is required. AEDs automatically charge themselves and provide step-by-step verbal instructions on how to use them.
  • First responder or healthcare provider actions:
  • Placement of paddles or sticky pads: Place two defibrillator paddles or adhesive pads, which are connected to the defibrillator, on the person’s chest. Position one paddle or pad below their right shoulder and the other below their left nipple. To prevent skin burns, the pads already contain conducting material. However, the healthcare provider will apply conducting material to the chest before using the paddles.
  • Initiate shock: If using sticky pads, press the designated button on the defibrillator machine to administer the shock. If handheld paddles are being used, simultaneously press the button on each paddle.
  • Purpose of defibrillation: The defibrillator temporarily stops the movement of the heart muscle, allowing the heart to generate an electrical impulse that can restore a normal rhythm. Essentially, defibrillation helps restart the heart.

By following these steps, you can effectively use a defibrillator to aid someone experiencing a cardiac emergency, while also ensuring the safety of those around.

After the procedure

In the event of a cardiac arrest, initial responders will administer CPR for two minutes and assess for the return of a pulse and normal heart rhythm. If necessary, they will continue CPR and provide additional defibrillation shocks. If the first attempt at defibrillation is unsuccessful, medications like epinephrine or amiodarone may be administered to correct the abnormal heart rhythm. If blood circulation is restored but the individual remains unresponsive, lowering their body temperature to a range of 32 to 36 degrees Celsius (89.6 to 96.8 degrees Fahrenheit) may be considered to protect and aid in the recovery of brain function. Once the patient’s condition stabilizes, cardiac catheterization may be performed as part of the treatment protocol.


Following cardiac arrest and defibrillation, recovery is a long-term process, often taking months or even years. Up to 40% of survivors may experience impairments that prevent them from resuming work or regular activities. Fatigue can be a limiting factor, and recovering from CPR-related rib fractures and other issues like walking difficulties or seizures may also take time. Occupational, physical, or speech therapy may be necessary.

If you witness someone collapse, call for local emergency assistance immediately.

Survivors of ventricular fibrillation are at high risk of recurrence and may receive an implantable cardioverter-defibrillator (ICD) to address the underlying cause. Regular check-ups are crucial, and the ICD battery typically needs replacement after about five years.