Commotio Cordis is the medical term for a rare disruption of the heart's electrical system resulting from a blunt impact to the chest that leads to sudden cardiac arrest.
Commotio cordis:
Occurs most often in baseball. Aside from baseball and lacrosse (three deaths of players from New York in two years; one near death of a player at a Massachusetts prep school), commotio cordis has occurred in softball, soccer and karate. In the fall of 2000, two football players died from blows to the sternum delivered by a helmet. In one case, a young boy reportedly died after his father poked him in the chest.
Is largely the result not of the force of the blow but from an incredibly untimely blow contacting the chest directly over the heart at just the wrong time -- the precise millisecond between heart contractions that throws the heart into a lethal abnormal heart rhythm called "ventricular fibrillation" or VF, which causes a useless quivering of the heart that results in a complete cessation of circulation instantly depriving the brain and other vital organs without circulation and oxygen. The blows usually causes no identifiable structural injury to the ribs, sternum or to the heart itself.
Occurs most often in healthy young athletes, who are especially at risk because the pliability of their chest walls. In a study of 55 cases of sudden cardiac arrest, 90% were 16 years of age or younger, 25 were playing in organized athletic events such as baseball, softball, and ice hockey. The remaining 30 children were playing informal sports at home, school or on the playground. None of the children showed evidence of any heart defect or diseases.
Cannot be completely eliminated through the use of protective equipment. Chest protectors do not appear to protect against it: athletes have died wearing chest protectors while playing baseball, lacrosse, hockey and softball. Studies have shown that the use of softer, lighter baseballs may reduce the risk of commotio cordis. Softer, heavier (so-called Reduction In Force or "RIF") baseballs may actually increase the risk of commotio cordis.