Heart Attack vs Cardiac Arrest

Although the terms are often used interchangeably, in fact a cardiac arrest and a heart attack are two entirely different situations.  A heart attack is the most common cause of cardiac arrest.

Cardiac Arrest

A cardiac arrest is when the heart stops functioning altogether.

Cardiac arrest happens when the heart stops pumping blood around the body. This means you are unconscious and not breathing. CPR must be performed immediately.

Heart Attack

A heart attack is one of the most common causes of cardiac arrest along with choking and electrocution.

A heart attack occurs when the blood supply to the heart muscle itself is blocked and the area beyond the blockage is starved of oxygen.  This causes that part of the heart muscle to die.  The damage to this part of the heart is permanent.

During a heart attack the heart is usually still able to function, although it will not be working properly.  The disability caused by this depends on the area of tissue damaged by the oxygen starvation.

If the damage is great enough it will disrupt the heart’s electrical pathways and cause a cardiac arrest.

How does your heart work?

Your heart is a four-chambered pump that is responsible for pumping oxygenated blood around the body to all your vital organs.
The chambers are known as atria and ventricles.

Within each heart beat the two top chambers collect blood from the body and lungs and contract, forcing blood into the two bottom chambers. These then contract forcing the blood out around the body.

The heart has it’s own electrical circuit (pacemaker) that sets the rate and rhythm of the contractions that make your heart pump (beat). It makes the two chambers at the top (the atria) contract together and then the two bottom chambers (ventricles) contract. This gives the characteristic “lub-dub” sound of a heart beat.

A heart normally beats 60-90 times a minute whilst at rest.  A pulse is an echo of your heartbeat.

In order to do its job properly your heart needs to have a very good blood supply.  In fact as the oxygenated blood is pumped out of your heart some of it immediately doubles back via your coronary arteries to give the heart its own excellent blood supply.

How do heart attacks happen?

Over time, the arteries in your heart may become furred up or clogged with cholesterol plaques.

Plaques are fatty deposits that line the artery walls and cause them to narrow and harden. This surface is quite rough and can cause blood clots to form.  These can completely block the artery, resulting in the death of an area of heart muscle. The pain from a heart attack is caused by the heart muscle dying and releasing toxins into the bloodstream.

Heart attacks can vary in severity from reasonably mild to fatal.  It can be difficult to recognise definitively that a heart attack is taking place.  However, they usually have a sudden onset, and can occur at any time; even at rest.

Key symptoms to look out for

• severe central chest pain, often described as tight, dull, pressure or mistaken for indigestion
• pain that radiates from the chest to the jaw or down the arms, back or shoulders, and lasts for more than 30 minutes
• a pale grey colour
• profuse sweating
• shortness of breath, feeling dizzy or faint
• a feeling of impending doom
• variable or irregular pulse

What should I do if I suspect someone is having a heart attack?

• Phone 999 or 112 immediately
• sit the person down to rest
• If the person is not allergic to aspirin and is over 16, allow them to chew a 300mg aspirin slowly
• Stay with person and monitor their breathing, if they stop breathing normally, commence CPR.

Useful resources:

First Aid Training

A range of training courses is available to help you learn CPR and other key life saving skills, including:

• One-day Emergency First Aid at Work
• Three-day First Aid at Work
• CPR Training (available for groups)

Other Resources

• Resuscitation Council (UK) interactive Lifesaver game – available online, and as tablet and phone apps.

HTS Training have made all reasonable efforts to ensure the accuracy of this information. However, there may be occasional and inadvertent errors. HTS Training therefore make no warranty, either express or implied, and accept no liability for any inaccuracies or omissions, nor for any decisions based on the information contained herein. Such decisions remain the responsibility of the reader. We would always recommend undertaking regular first aid training, and following the latest guidance provided as a part of that course.