What may have caused Christian Eriksen to collapse?

The footage of Denmark's midfielder Christian Eriksen collapsing on the pitch on Saturday and receiving chest compressions as stunned fans at Copenhagen’s Parken Stadium looked on was shocking.

The player was said to be “awake” and had been rushed to hospital where he was being stabilised on Saturday night.

It is not yet known what caused Eriksen to collapse and his heart to apparently stop, but it is not the first time football has seen witnessed such scenes.

Many will remember the collapse of Bolton Wanderers star Fabrice Muamba in 2012. Both men were at their physical peak with no signs of hidden danger.

So what can trigger a sudden cardiac arrest in young, fit, healthy sports men and women.

Dr Richard Till is a consultant cardiac electrophysiologist at the Norfolk and Norwich Hospitals Trust specialising in the electrical activity of the heart.

He told The Independent what happened to Christian Eriksen was rare and it was likely the fast CPR he received on the pitch that helped to save the player’s life.

He said a sudden cardiac arrest was not the same as a heart attack triggered by underlying coronary heart disease. This is where fatty deposits block arteries to the heart causing muscle to die, which can stop the heart beating.

“It is very unlikely to be the cause in his case. What is more likely is that he has a congenital condition that has not been picked up until now.”

He said these other causes of a sudden cardiac arrest can include a condition known as hypertrophic cardiomyopathy which can cause the heart muscle to thicken and make it harder to pump blood.

It’s also possible Eriksen had a viral infection that led to myocarditis, an inflammation of the heart muscle.

Other causes of a cardiac arrest can be linked to electrical faults in the signals that trigger the different sections of the heart to pump blood. This can lead to an abnormal rhythm, reducing blood flow out of the heart to organs like the brain and leading people to collapse. One such condition known as Brugada syndrome is an inherited condition, another similarly inherited condition known as long QT syndrome can also affect how the heart beats.

Dr Till said these can be intermittent and potentially missed by the ECG heart traces and ultrasound scans that are common health assessments for professional footballers and other athletes.

He added: “The key is to keep oxygen and blood flowing to the brain through chest compressions and I understand Christian Eriksen received very prompt CPR on the pitch. He would have been connected to a defibrillator which would check his heart rhythm and shock the heart to return it to a normal rhythm if appropriate. Which is what I understand happened.

“This is very, very uncommon for someone in the professional field. It is more common in amateur athletics and people running marathons for the first time, for example, but again still rare.

“It’s likely his youth and fitness helped his brain to survive until they started CPR.”

He said quick CPR was crucial, adding: “It is a skill everyone should know. This is a very public occurrence of something that in reality is very rare. It shouldn’t put anyone off exercising and should encourage everyone to learn CPR. It really is a skill that saves lives.”