During Cardiac Arrest, What Happens to a Person?

One moment someone is chatting, walking or sitting at their desk. The next, they’re on the floor. That’s cardiac arrest, and it rarely gives anyone time to prepare.

Most of us have never seen it happen. So here’s what actually goes on inside the body, and what you can do if it happens near you.

As Dr. Krishna Dhoot, Interventional Cardiologist, puts it: “The heart’s rhythm has failed, but the brain can’t wait. When a bystander starts compressions early, it gives the person a much better chance while help is on the way.”

Your heart runs on tiny electrical signals. In sudden cardiac arrest, those signals go haywire. The heart quivers or simply stops, and it can’t push blood around anymore.

The effects show up fast:

• No blood flow to the brain, lungs or kidneys
• The pulse can’t be felt
• Breathing stops, or turns into slow, noisy gasps
• The person collapses and doesn’t respond

The usual culprit is a chaotic rhythm called ventricular fibrillation. It often shows up in people with coronary artery disease, a weakened heart muscle or an inherited rhythm problem. Sometimes there’s no obvious cause until the heart is examined later.

Surprisingly little. Most people black out within seconds, so there’s usually nothing to remember afterwards.

A few notice palpitations, dizziness or chest discomfort just before. Many don’t.

It’s the people around them who see the real picture: a sudden fall, no reply when you call their name, no normal breathing. That’s frightening to watch, and it’s exactly when a bystander’s response counts.

The brain is greedy for oxygen. It can’t store any, so when blood stops moving, it starts running short almost immediately.

Unconsciousness comes first. After roughly 4 to 6 minutes without circulation, brain cells may start getting damaged, and longer gaps raise the risk of lasting brain injury.

That’s why CPR is so useful. Compressions don’t restart the heart by themselves, but they keep some blood reaching the brain until a defibrillator or medical team steps in.

Honestly, many cases come with none. But some people get hints in the days or weeks before:

• Chest pressure or pain
• A racing, fluttering or skipping heartbeat
• Fainting spells, or nearly fainting
• Breathlessness that feels out of proportion
• Tiredness that doesn’t go away
• A relative who died suddenly at a young age

Learn more about heart attack symptoms, warning signs, and risk factors to understand when symptoms may need attention.

A heart attack can set off a cardiac arrest. They’re related, but they aren’t the same event.

Don’t freeze, and don’t wait to be 100% sure. If someone has collapsed and isn’t responding or breathing normally, treat it as an emergency.

1. Tap and shout. Check whether they respond.
2. Call 112 (or 108 for an ambulance). Send someone to find an AED if there’s one nearby.
3. Push on the centre of the chest. Use the heel of your hand, press hard and fast at about 100 to 120 beats a minute, and let the chest come back up each time.
4. Switch on the AED when it arrives and follow its spoken instructions.
5. Keep going until paramedics take over.

Skip the water, and don’t try to prop them up or shake them awake.

Straight away, if someone:

• Collapses and won’t respond
• Isn’t breathing, or is only gasping
• Has chest pain lasting more than a few minutes, especially with sweating or breathlessness

Not every situation is an emergency, though. If you’ve had repeated fainting, unexplained palpitations, or a family history of sudden cardiac death, don’t sit on it. A cardiac evaluation, which may include an ECG, 2D Echo or TMT, helps assess how your heart is working.