Heart & Defibrillator Facts

What is a heart attack?

Your heart needs an oxygenated blood supply to survive. Blood is delivered to the heart by coronary arteries, if these arteries become blocked the area of heart muscle they feed will die, this is what we call a heart attack. The heart attack victim is usually conscious and usually has signs and symptoms, these can include:

  • Chest pain – often described as crushing or a tightening, it may be severe or quite mild.
  • Pain radiating down the arm, spreading to the neck, jaw, abdomen or back – it may be severe or just mild discomfort.
  • Nausea – you may vomit.
  • Light headiness or dizzy
  • Shortness of breath.

If you think you are having a heart attack, or you suspect someone else is, dial 999, do not delay. 1 in 2 heart attacks are fatal, the faster you receive treatment the better the chances of survival.

What is a cardiac arrest?

A cardiac arrest is when the heart suddenly stops pumping blood around the body; it is usually without warning and is sudden, there may be no signs of distress or discomfort.

The patient will collapse, there will be no discernible blood pressure or pulse and they will stop breathing, they are clinically dead. For a very short while, following cardiac arrest, the heart muscle will ‘quiver’ this is known as ventricular fibrillation.

Without immediate resuscitation and the use of a defibrillator the patient will die. If you witness a cardiac arrest call 999 immediately, commence resuscitation (CPR) and use a defibrillator if available. Do not stop CPR before help arrives.

What is Ventricular Fibrillation (VF)?

VF is the heart failing to beat properly, the heart muscle ‘quivers’ as opposed to contracting and is no longer pumping blood around the body. The patient will suddenly collapse, they will be unresponsive and have no discernible pulse or blood pressure. Untreated, ventricular fibrillation is fatal.

Dial 999 immediately. Commence CPR and use a defibrillator if available. Do not stop CPR before help arrives.

What is a defibrillator?

A defibrillator or Automated External Defibrillator (AED) is an electronic device used to administer an electric shock to a heart in ventricular fibrillation. Basically the AED will hopefully ’shock’ the heart back into a normal rhythm.

The latest AEDs are portable and light and very easy to use, do not be afraid of them, they are designed to be used by people with little or no experience, they will not shock someone who doesn’t need it.

The AED will deliver the shock automatically and most have voice and visual prompts. It is important that CPR is interrupted ONLY for analysis of rhythm and delivery of shock (the machine will tell you). Clinical studies have shown that for best results shocks should be administered every 2 minutes, it is vital that between times good quality CPR is administered.

The Resuscitation Council UK has an excellent website with lots of information on the use of AEDs.


Pie chart illustrating the number of deaths in the US from various causes.

Pie chart source: http://www.sca-aware.org/about-sca

In The US A School Student Was Saved In Class Because Of A Defibrillator

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