Images of Fabrice Muamba collapsed on a football pitch brought back uncomfortable memories for many in Spain.
Seven professional players have died suddenly in Spain in the last decade after suffering heart failure. One died in the 1970s, two in the 1980s and one in the 1990s, unfavourable statistics compared to other countries - and there is no conclusive evidence to say why.
Antonio Puerta, the Sevilla full-back, collapsed on the pitch away from the ball during a game with Getafe in 2007.
An outpouring of grief followed and Spain did not know what to do. Heart conditions are extremely difficult to detect in fit young men and Puerta died of dysphasia, a defect in the generation of cells in the heart rather than a heart attack, which is usually caused by a build-up of cholesterol in the artery walls.
But some of the deaths could possibly have been prevented and some good came from the tragedy of Puerta's death. Every professional club and every sports centre in Spain is now required to have a medical kit which includes a heart defibrillator. The kit, which costs €5,000 (Dh24,179) and includes 22 other items, must be within easy access of the pitch.
The defibrillator has already saved lives. In 2010, Miguel Garcia collapsed during a televised second division game between Sevilla's rivals Real Betis and UD Salamanca.
Doctors from both teams rushed on to the field and resuscitated Garcia, whose heart had stopped beating for 25 seconds. He was legally dead according to one of the doctors, but survived because of the defibrillator, which was used six times on Muamba on Saturday. Garcia's life was saved, although he had to retire from football with immediate effect, but he was 31 and had enjoyed a full career.
Others players were not so fortunate. In 2008, Real Madrid's Rueben de la Red had just broken into the full Spain team and was in the squad which were crowned European champions. The midfielder, then 23, collapsed during a Copa del Rey game against Real Union.
Subsequent tests were inconclusive and, while de la Red hoped to play again, he was forced to announce his retirement in an emotional speech in 2010.
De la Red's Spanish Under 21 teammate Sergio Sanchez similarly announced his retirement in 2010 after complaining of chest pains. Tests found that he had a dilated aorta, for which he had successful surgery.
Like Puerta, Sanchez was with Sevilla, but his story had a happier ending and, after a year out, returned to play in January 2011. He transferred to Malaga in June 2011 and has resumed a normal career since.
The problems have not been confined to the pitch.
Dani Jarque, the captain of Espanyol, died in the team hotel during their 2009 pre-season. Andres Iniesta dedicated the goal which won Spain the World Cup to him, while Espanyol fans still cheer throughout the 21st minute of every home game.
Jarque wore 21 and this is a poignant reminder of one of the tragic losses which continue to haunt Spanish football.