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Does a defibrillator restart a stopped heart?

Published on 13th January 2023

Unfortunately, a defibrillator/AED will not restart a heart once it has stopped beating.

This is a common question for those unfamiliar with lifesaving technology. Does a defibrillator restart a stopped heart?

The short answer is no; an automated external defibrillator (AED) cannot restart a heart that has stopped beating due to cardiac arrest.

An AED can shock a heart when it has lost its rhythm. This is known as ventricular fibrillation, and the shock of an AED sends electrical pulses to the heart to restore it to a normal rhythm. If successful, this will cause the heart to start beating again.

Ventricular fibrillation is when the heart’s electrical signals become chaotic, causing the heart to quiver instead of beating in a normal rhythm. This can be fatal if left untreated as it keeps the heart from pumping blood throughout the body. Without blood, vital organs and bodily systems begin to shut down, leading to loss of consciousness and death within minutes.

Our range of AEDs is designed to recognise this type of arrhythmia and respond by sending electrical pulses to reset the rhythm back to normal. The device will analyse the heart rhythm and determine if a shock is necessary, then deliver an electrical current that can help restore the heartbeat to normal. It’s important to remember that this only works if the arrhythmia has been detected in time and the AED is used correctly.

It is important to note that while an AED can help with ventricular fibrillation, it does not guarantee survival. The effectiveness of the shock also depends on how quickly it is administered, as well as the overall health of the person receiving the shock. For these reasons, early access to an AED and prompt bystander CPR are critical for increasing the chances of survival after cardiac arrest.

Why does ventricular fibrillation occur?

Ventricular fibrillation occurs when the electrical impulses that control heart rhythm become chaotic or disorganised. This can be caused by several factors, including coronary artery disease, electrolyte imbalance, scarring on the heart from previous damage or infection, and even an underlying genetic condition.

What steps reduce the risk of ventricular fibrillation?

Practising a healthy lifestyle is the best way to reduce the risk of ventricular fibrillation. This includes eating nutritious foods, exercising regularly, and avoiding smoking and excessive alcohol use. Additionally, those with existing heart conditions should take steps to manage their condition through prescribed medications, lifestyle changes or other treatments recommended by their doctor. See our guide on foods for a healthy heart.

What is arrhythmia?

Arrhythmia is an abnormal heartbeat, which various underlying medical conditions can cause. It occurs when the heart beats too fast (tachycardia) or too slow (bradycardia). Other arrhythmias include atrial fibrillation and supraventricular tachycardia. These irregular heartbeats can lead to serious health problems if not treated, including stroke and sudden cardiac arrest.

How does an AED help during SCA?

The key role of an AED is to detect and treat arrhythmia quickly. If a shock from the AED is effective, it can help reset the heart’s rhythm and allow blood to flow through the body again. Even if the shock is not successful in restoring normal rhythm, using an AED will provide more time for medical professionals to respond and treat the person suffering from cardiac arrest.

What steps should be taken if the heart has stopped?

If a person’s heart has stopped beating, it is critical to call 999 immediately and perform CPR. This can help keep the body alive until a defibrillator, or medical personnel can arrive on the scene. Once an AED is available, it should be used as soon as possible to give the person the best chance of survival.