Lifesaving Technology: Understanding Defibrillators


Cardiac arrest can strike anyone at any time. It occurs when the heart malfunctions and stops beating unexpectedly. A key tool that can help save lives during a cardiac emergency is the defibrillator. Defibrillators deliver an electric shock to re-start the heart and restore a normal heart rhythm. In this article, we will take a deeper look at defibrillators – what they are, how they work and their role in emergency response.

What is a Defibrillator?

A defibrillator, commonly referred to as a “defib”, is a portable electronic device that can deliver an electric pulse or shock to the heart in order to restore normal heart rhythm. During cardiac arrest, the heart develops a life-threatening abnormal heart rhythm called ventricular fibrillation. This causes the heart to quiver instead of pumping blood effectively. A defibrillator treats ventricular fibrillation by delivering a measured electric shock. This depolarizes a critical mass of the heart muscle, terminating the ventricular fibrillation, and allowing the heart’s natural pacemaker to restart normal sinus rhythm.

There are two main types of defibrillators – automated external defibrillators (AEDs) and implantable cardioverter defibrillators (ICDs). AEDs are small, lightweight devices that are designed to be easy to use for the layperson or emergency medical technician. ICDs are implanted surgically in patients who are at high risk of cardiac arrhythmia. ICDs continuously monitor the patient’s heart rhythm and can deliver shocks automatically if a life-threatening rhythm is detected.

How Defibrillators Work

The key components that allow defibrillators to work include:

– Pads or electrodes – These are adhesive patches that are placed on the patient’s bare chest. They conduct the electrical pulse from the defibrillator to the heart muscle.

– Battery – Provides power to the defibrillator circuitry and delivers the shock to the patient through the pads.

– Monitor – Has sensors that analyze the heart’s rhythm through the pads/electrodes. It can detect ventricular fibrillation.

– Computer processor – Interprets the heart rhythm and decides if a shock is needed based on preset parameters.

– Charge delivery system – Uses the battery to store and deliver controlled, measured electric shock through the pads to the heart muscle.

When activated on a patient in cardiac arrest, the defibrillator monitors the heart rhythm through the pads. If ventricular fibrillation is detected, it charges then instructs the person to press the shock button to deliver the electric pulse. This depolarizes a critical mass of heart muscle cells, ending the chaotic rhythm and allowing normal rhythms to resume through the body’s natural pacemakers.

Defibrillators in Emergency Response

Early defibrillation within the first few minutes of collapse can be lifesaving in many cases of cardiac arrest. For this reason, public access defibrillation (PAD) programs have been established worldwide to improve access to early defibrillation. AEDs are placed in public locations where collapse from cardiac emergencies may occur such as airports, casinos, shopping malls etc. These are intended to be operated by laypersons who receive CPR/AED training.

When activated, most AED machines have audio and visual prompts to walk users through operation. They analyze the heart rhythm and will only instruct a shock if ventricular fibrillation or other shockable rhythm is detected. For non-shockable rhythms like asystole or pulseless electrical activity, CPR is prompted by the AED. Many public AED programs also have targeted response plans so that Emergency Medical Services are simultaneously dispatched if possible.

Responsive implantable devices have also improved outcomes from cardiac arrest at home or in public locations. ICDs can detect lethal rhythms and deliver treatment without needing human intervention. The incidence of unwitnessed out-of-hospital cardiac arrest is declining likely due to proliferation of these devices and PAD programs. Defibrillation within 3-5 minutes has been shown to increase survival from under 10% to over 50% in some studies.

Expanding Technology

Defibrillator technology is continuously advancing to further optimize resuscitation outcomes. Newer AED models incorporate monitoring telemetry for event documentation which can improve quality of CPR delivered. Additional sensors are being developed to analyze other vital signs like end tidal carbon dioxide monitoring during CPR. Computer algorithms to detect cardiac rhythms are also optimizing detection accuracy which reduces unnecessary shocks and gets patients faster advanced medical care.

Miniaturized implantable loop recorders have been developed to remotely monitor patients at higher risk of arrhythmias. These allow arrhythmia events to be captured without requiring physical examination of a device. Future directions may involve incorporating pacing capabilities with defibrillation therapy. Researchers are also investigating more patient-specific treatment approaches with defibrillation like using impedance thresholds for optimal energy delivery based on individual heart size.


In summary, defibrillators play a pivotal role in improving survival from cardiac emergencies in both medical and public access settings. As technology advances and more defibrillators are deployed through PAD programs, the percentage of victims who receive early defibrillation will increase. For the nearly 100,000 annual cases of out-of-hospital cardiac arrest, defibrillators have the potential to save many more lives each year. It is hoped that continued innovations will help maximize the benefit from this lifesaving technology.

1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it