How can athletes play with ICDs, and what happens when it goes off?

Image source, Getty Images Image caption, Christian Eriksen is Denmark's record appearance-maker By Daniel Austin BBC Sport senior journalist Published 11 minutes ago When Christian Eriksen collapsed during Denmark's 2-1 friendly victory over Ukraine on Sunday, he was assisted by a device which was fitted to support his heart after he suffered a cardiac arrest during a Euro 2020 match. The implantable cardioverter defibrillator (ICD) sits in Eriksen's chest, with wires connecting it to his heart. It provides a shock to either restart the heart if it stops beating, or to jolt it back into a regular rhythm if abnormalities are detected. "The pacemaker responded as it should," said Denmark's national team doctor Morten Boesen on Sunday. The sight of Eriksen dropping to the turf, before being surrounded by visibly upset team-mates while being treated by medical staff behind a makeshift curtain, was frighteningly reminiscent of his previous collapse, which shocked football fans around the world. So, how can athletes return to elite-level sport after having an ICD fitted, what are the risks, and what happens when the device goes off? 'Athletes will never say stop' The need for an ICD - which is around half the size of a mobile phone - to be fitted can be caused by a variety of different health conditions, including heart failure, coronary heart disease, and arhythmias. Depending on the exact illness an athlete is suffering from, a return to competition is possible. "All cases are individual," says Dr. Amanda Lahti, a doctor and researcher in sports medicine. "It is a shared decision model – you take opinions from the club, the player, their agent, and medical experts, looking at the risks and the potential benefits. You then take a collective decision about whether a player can continue with their career or if they should stop. "The difficulty with that is the athlete themselves has the final word, and they will never say 'stop'. They are willing to take risks that perhaps you or I would not." When Eriksen suffered his cardiac arrest in June 2021, he was playing his club football for Inter Milan in Italy's Serie A, one of a minority of leagues which prohibits players fitted with an ICD from competing. Eriksen made his return first with Brentford and then Manchester United in the Premier League, where there is no blanket rule, and players must undergo individual testing to assess whether they are healthy enough to play. "I don't see any risk, no," he told BBC Sport in 2022. "I have an ICD, if anything would happen then I am safe." To play this video you need to enable JavaScript in your browser. This video can not be played Figure caption, Eriksen told BBC Sport "it is a miracle that I am back playing football" in 2022, following the fitting of his ICD World football's governing body Fifa, and its European counterpart Uefa, allow players with ICDs to participate in their competitions, as does Germany's Bundesliga, where Eriksen spent the past season p