Understanding cardiac arrest

Cardiac arrest is a life-threatening emergency where the heart suddenly stops beating effectively, cutting off blood flow to the brain and other vital organs. Without prompt action, it leads to death within minutes.

Unlike a heart attack, which involves a blocked artery, cardiac arrest is primarily an electrical malfunction. The heart goes into an irregular rhythm like ventricular fibrillation and cannot pump blood. Without rapid treatment — usually CPR and defibrillation — the chances of survival plummet with each passing minute.

The chain of survival

The American Heart Association defines a “chain of survival” — a series of steps that dramatically improve survival rates in out-of-hospital cardiac arrest:

  1. Immediate recognition and calling emergency services

  2. Early CPR with high-quality chest compressions

  3. Rapid defibrillation with an AED

  4. Advanced medical support from emergency responders

  5. Post-cardiac arrest care in a hospital

CPR and AED use are the second and third steps — and they are most often delivered by bystanders before professional help arrives.

Why time matters

In cardiac arrest, every second counts. The brain begins to suffer irreversible damage within 4 to 6 minutes of oxygen deprivation. If defibrillation occurs within the first 3 minutes, survival rates can exceed 70%. But after 10 minutes, survival chances are near zero without intervention.

Each minute without CPR or AED decreases survival by 7–10%. That’s why bystander action is so critical — waiting for emergency responders may take too long.

What is CPR?

CPR (Cardiopulmonary Resuscitation) is a lifesaving technique that uses chest compressions — and sometimes rescue breaths — to manually pump blood through the body during cardiac arrest.

There are two main types:

  • Hands-only CPR: Recommended for untrained bystanders. Focuses solely on chest compressions.

  • Conventional CPR: Involves both chest compressions and rescue breaths, usually performed by trained responders.

High-quality CPR buys time by delivering oxygen to the brain and organs until defibrillation or medical help can restore normal heart function.

Steps to perform CPR

If you witness someone collapse and they are unresponsive with no pulse:

  1. Call emergency services immediately.

  2. Check for breathing and pulse. If absent, begin CPR.

  3. Place the heel of one hand on the center of the chest.

  4. Place the other hand on top and interlock fingers.

  5. Push hard and fast — at least 2 inches deep, 100–120 compressions per minute.

  6. Allow the chest to fully recoil between compressions.

  7. Continue until help arrives or an AED is available.

If you are trained, you can give rescue breaths in a 30:2 ratio (30 compressions to 2 breaths).

What is an AED?

An AED (Automated External Defibrillator) is a portable medical device that analyzes heart rhythms and delivers an electric shock to restore normal heart function.

AEDs are designed to be user-friendly and can be found in:

  • Schools

  • Airports

  • Offices

  • Gyms

  • Shopping centers

Modern AEDs provide step-by-step audio instructions, making them accessible to the general public — no medical training needed.

How to use an AED

  1. Turn on the AED and follow the voice prompts.

  2. Expose the person’s chest and attach the adhesive electrode pads.

  3. Ensure no one is touching the person.

  4. Allow the AED to analyze the heart rhythm.

  5. If a shock is advised, press the button when prompted.

  6. Immediately resume CPR after the shock.

Continue to follow the AED’s instructions until emergency medical services arrive.

AED effectiveness

Defibrillation is the only treatment for ventricular fibrillation and pulseless ventricular tachycardia — the most common rhythms in cardiac arrest.

  • An AED shock delivered within the first 3 minutes can lead to survival rates as high as 70–80%.

  • For each minute defibrillation is delayed, the chance of survival drops by about 10%.

  • Bystanders using AEDs before EMS arrives doubles or even triples survival chances.

This makes AEDs one of the most important tools in emergency first aid.

Common fears and myths

Many people hesitate to perform CPR or use an AED because of fear or misinformation:

“What if I hurt them?”
CPR may cause broken ribs, but doing nothing is far worse.

“What if I do it wrong?”
Any attempt at CPR is better than no action. Hands-only CPR is simple and effective.

“Can I be sued?”
Good Samaritan laws in many countries protect bystanders who provide emergency care in good faith.

“AEDs are only for professionals.”
False. AEDs are designed for public use and are safe, even if the victim doesn’t need a shock — the device won’t deliver one unless necessary.

Who should learn CPR and AED?

Everyone. Cardiac arrest can happen anytime, anywhere — in your home, workplace, or on the street.

People who especially benefit from training include:

  • Parents

  • Teachers

  • Coaches

  • First responders

  • Workplace safety officers

Many organizations offer certified training courses, including the Red Cross and the American Heart Association. Even a one-hour workshop can make a difference.

CPR and AED for children

Cardiac arrest can affect children due to choking, drowning, or congenital heart defects.

Differences when performing CPR on children:

  • Use one hand for compressions in smaller children

  • Compress the chest about 1/3 of its depth (about 2 inches)

  • Provide rescue breaths with less volume

AEDs can be used on children, often with pediatric pads or a child setting. Always follow the device’s instructions.

Survival statistics

The impact of CPR and AED is clear in the numbers:

  • Bystander CPR can double or triple survival chances

  • Only about 10% of out-of-hospital cardiac arrest victims survive without intervention

  • With both early CPR and defibrillation, survival can rise to over 50%

  • Most cardiac arrests occur at home — where family members are the first and only chance for help

Training more people in CPR and AED use is one of the most effective public health strategies for reducing sudden cardiac death.

Public access to AEDs

Many communities have expanded access to AEDs in public places. You can often find them:

  • Mounted on walls near entrances

  • In glass cases like fire extinguishers

  • With signage that reads “AED” or shows a heart with a lightning bolt

If you're unsure where to find one, ask staff members or look for a visible sign near elevators or reception desks.

Post-resuscitation care

Once the heart is restarted, the patient still needs advanced medical care. Common treatments include:

  • Cooling therapy (therapeutic hypothermia)

  • Mechanical ventilation

  • Cardiac catheterization

  • Medications to stabilize heart rhythm

Even if the person wakes up after CPR and AED use, emergency services should still be called. They may need hospitalization and further monitoring.

CPR training options

You can learn CPR and AED use through:

  • In-person classes at local hospitals or community centers

  • Certified courses from the American Heart Association or Red Cross

  • Online blended courses with in-person testing

Many workplaces offer CPR training as part of their safety programs — consider requesting it if your employer doesn’t already provide it.

Technology and future advances

New technology is improving emergency response and AED accessibility:

  • Mobile apps show nearby AED locations

  • Smartwatches and phones can detect abnormal heart rhythms

  • Drones delivering AEDs to remote areas are being piloted in some countries

  • Wearable AEDs and home devices are becoming more common for high-risk individuals

These advances are promising, but nothing replaces the need for trained, confident bystanders.

The power of preparation

CPR and AED use are among the simplest yet most powerful ways ordinary people can save lives. Learning what to do in a cardiac emergency transforms fear into action.

By being prepared:

  • You can keep someone alive until help arrives

  • You reduce the chance of brain damage or long-term disability

  • You may save a loved one — most cardiac arrests happen at home

Every second truly matters. Your hands could be someone’s only chance at survival.

Conclusion

Cardiac arrest strikes suddenly, but survival is possible with immediate action. CPR and AEDs work together to restore life when the heart stops. These tools are simple to use, require no medical background, and are available in many public spaces.

The more people trained, the more lives can be saved. Whether you’re a parent, coworker, friend, or passerby, you can be a hero. Learn CPR, locate your nearest AED, and be ready — because when every second counts, someone will be counting on you.