The devices are voice-activated and someone with no first aid experience can be trained in just four hours.

Defibrillators are said to be easy to use

They can tell whether the patient requires a "shock" to restart the heart or whether conventional cardio-pulmonary resuscitation (CPR) and first aid should continue until paramedics arrive.

Steve Jelf, director of the Forth Valley Red Cross branch, said people should not be concerned about security guards with no previous medical knowledge being trained in their use.

"We are talking about a thing called an automatic external defibrillator, which is just that - a fool-proof automatic machine that talks you through the system," he added.

Customer safety

Colin Caulfield, operations manager at the shopping centre, said: "Over recent years, the Howgate Shopping Centre has been evolving the highest levels of customer safety.

"Our customers are very important to us, their safety is paramount and we place this above all else.

"Our trained staff exemplify the standards that we strive towards, which is stress free and convenient shopping for all our customers."

The machines are "fool-proof"

The defibrillators were introduced in England in April this year under a UK Government scheme.

The Department of Health aims to install 700 more in bus and railway stations, shopping centres and airports in England over the next year.

The survival rate among people in Scotland who suffer heart attacks is about 5%, which Mr Jelf said could rise considerably if they were more widely available.

Heart defibrillators have been introduced in public places across the US, including Chicago's O'Hare airport, where the survival rate is 73%.

In Las Vegas, where the machines have been sited in casinos, the rate is 58%.