A heart attack is the result of part of the heart muscle being starved of oxygen and nutrients by a blocked blood vessel.

However, while treatment to restore blood flow is vital to prevent serious damage to the heart, research has now shown that once blood starts to flow again in the damaged areas, this can itself further damage the heart.

Although a form of oxygen called free radicals is thought to be responsible for causing this damage, little is known about exactly what happens.

Researchers at London's St Thomas' Hospital, led by Dr Michael Shattock and Dr Philip Eaton, have found a way of marking proteins in heart muscle that are damaged by free radicals.

The new project aims to extract these proteins and identify them as a step towards finding treatments or preventative measures that stop the damage.

Heart is damaged by treatment

Dr Eaton said: "At the moment it's almost a no-win situation.

"The blood supply needs to be restored to stop serious and possibly life-threatening damage to the heart.

"But the very process of getting the blood back to the muscle itself causes damage. If we can find out exactly how these proteins are affected, we might be able to develop a way of reducing the effects."

The research is backed by a grant of more than £100,000 from the British Heart Foundation.