How do defibrillators work?

How do defibrillators work?

Defibrillators are typically associated with frightening scenes from television shows or movies where patients get jolted with electricity through large paddles. Everyone has seen a scene with medical attendants anxiously telling everyone to make way, shouting ‘clear!’ amidst CPR and defibs.

Thankfully, those machines have developed into a lightweight, portable medical device that can restore a regular heartbeat by sending a shock or an electric pulse to the heart. 

Defibrillators have saved many lives by preventing or correcting an arrhythmia – a heartbeat that is uneven, too slow or too fast. It can also restore a heartbeat if your heart suddenly stops. 

More on arrhythmia

A heart arrhythmia occurs when the electrical impulses that coordinate the heart’s beating don’t work correctly, causing your heartbeat to be too fast, too slow, or at an irregular pace, explains Mayo Clinic.

Heart arrhythmias can feel like a fluttering or racing heart and may be harmless. Some arrhythmias can cause bothersome — sometimes even life-threatening — signs and symptoms. Treatment for heart arrhythmia can often control or eliminate fast, slow or irregular heartbeats. In addition, because troublesome heart arrhythmias are usually made worse — or are even caused — by a weak or damaged heart, you may be able to reduce your arrhythmia risk by adopting a heart-healthy lifestyle.

Eat a well-balanced diet that incorporates all food groups and lean meats. 

Different types of defibrillators

There are three types of defibrillators – Automated External Defibrillators (AEDs), Implantable Cardioverter Defibrillators (ICDs) and Wearable Cardioverter Defibrillators (WCDs).


An AED is a lightweight, battery-operated, portable device. It checks your heart rhythm and restores a normal rhythm by sending a shock to your heart. This device helps people having a sudden cardiac arrest. 

Sticky pads with sensors, called electrodes, are attached to your chest if you have a cardiac arrest. The electrodes send information about your heart rhythm to the AED computer. Your heart rhythm is analysed, and finds out if you need an electric shock to your heart. 


ICDs check for arrhythmias by being placed surgically in your chest or abdomen. Arrhythmias can interrupt the blood flow from your heart to the rest of your body, causing your heart to stop. If this happens, the ICD will send a shock to your heart to correct the arrhythmia.

An ICD gives off a low-energy shock to speed up or slow down an abnormal heart rate. It can also send a high-energy shock to correct a fast or irregular heartbeat. The ICD is similar to a pacemaker because of the low-energy electrical shocks. Pacemakers only deliver low-energy electrical shocks. 


According to the National Heart, Lung and Blood Institute, WCDs have sensors attached to your skin. Wires connect them to a unit that assesses your heart’s rhythm. It delivers shocks when your heart needs it. 

The WCD is similar to an ICD. It can deliver low- and high-energy shocks when necessary. The device attaches a belt to a vest worn under your clothes. The vest can be fitted to your size and programmed to detect a particular heart rhythm. 

The sensors can detect when an arrhythmia occurs and notifies you too. If you feel that the shock is not needed, you can turn off the alert. If you don’t turn the alert off, a shock will correct the rhythm within one minute. 

During an episode, the WCD can distribute repeated shocks. Replace the sensors after an episode. A record of your heart’s activity can be sent to your doctor. 

What to expect from electric shocks

Electric shocks can take time to get used to. Defibrillators can deliver electrical energy to your heart at different strengths.  It isn’t painful, but the sensation can be unpleasant. The site of the shock can be tender after the event and will need time to heal. Shocks can be low energy and high energy.

Low-energy shocks

The low-energy electrical shocks are not painful. You may not notice them or feel fluttering in your chest. 

High-energy shocks

These shocks last a fraction of a second. They can be intense or painful. High-energy shocks may feel like thumping or a kick in your chest. One or two strong shocks over a short period can make the symptoms disappear and maybe a sign that your device is working. 

You should notify your doctor and make an appointment for that day or the next day. The doctor will assess your condition and the device. 

Unnecessary shocks

After your surgery and while you adjust, your defibrillator may release unnecessary shocks. A damaged wire or fast heart rate can trigger these types of shocks. 

The shocks can occur if you forget to take your medication. Some people feel phantom shocks even when the device does not detect an arrhythmia. 

Stay connected and protected! 

Time and accuracy are the most critical factors in an emergency like a heart attack! It can distinguish between a good or bad outcome.

It would be best to plan for when things go wrong; iER is that safety net. 

Because you have the iER app on your phone, you will always be connected. The app contains unique built-in alerts and GPS tracking functionality! That means that the emergency services can locate you with ease, ensuring a swift, hassle-free rescue.


iER offers members three different plan options.

It is Standard that everyone gets full and unrestricted access to the service providers on the network, as the iER App is free on all devices and networks. Suppose you want to upgrade to a package that allows you access to utilise iER’s total cover. In that case, there is a Premium Plan and a Premium Plan Plus that offer loads of extras for post-emergency protocol for a nominal fee.


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