This type of injury, called commotio cordis, previously has been associated with competitive sports such as softball, baseball and hockey. But it appears such injuries are occurring more often and in a wider variety of settings, the researchers say.
"This is a new type of public health problem related to the dangers of a strike in the chest," says Dr. Barry Maron, lead author of the study, which was presented today at an American Heart Association conference in Anaheim, Calif.Nevertheless, the problem still remains a rare one, Maron says. He's the director of the Hypertrophic Cardiomyopathy Center at the Minneapolis Heart Institute Foundation.
The injuries in question do not involve any structural damage to the chest wall or heart, nor do the victims have abnormal hearts or heart disease, the researchers add. In fact, they say, the exact cause of death often is unclear.
To examine the possible causes of commotio cordis, the researchers created a registry of 124 confirmed cases of people who had suffered this type of injury. The victims ranged in age from 1 to 44, with an average age of 14. Most of the cases involved people 18 years or younger, and almost half occurred in children 12 or under.
Most of the cases, 62 percent, involved organized sports, and the rest resulted from everyday activities, recreational sports, discipline from a parent or minor scuffles around the house or playground. Some, though, included what the researchers labeled more "bizarre circumstances" -- such as impacts from snowballs, a tennis ball filled with coins, a dog's head and a plastic sledding saucer.
Younger children are more vulnerable, Maron says, because they generally have narrower chest cages and underdeveloped chest muscles.
Only 18 of the 124 victims studied survived their accident, usually because they had received prompt cardiopulmonary resuscitation, the study says.
Other studies, however, suggest that the incident itself is almost an accident of timing, says Dr. Mubadda A. Salim, chief of pediatric cardiology at the University of Maryland Hospital for Children. The fatal blows were administered at the precise moment in the heart's cycle to cause arrhythmia or irregular heart beat, similar to what you would find after a heart attack, he adds.
"It's not the amount of energy, it's the timing of the energy," Salim says.
The new registry created by the researchers will make comprehensive information on causes and risk factors for such injuries more accessible to doctors who've never seen this rare condition, Salim says. And, he adds, knowing the risks and causes also might encourage people to change their behavior.
But the registry also might help alleviate guilt on the part of the usually innocent perpetrator.
"If you're playing with your son or daughter and you just happen to touch their chest and they drop dead, there is a big guilt factor," Salim says. "The registry creates the possibility that this is not your fault. Some people need to get that information so they can go on with their lives."
According to the American Heart Association, the most effective treatment for cardiac arrest is prompt CPR and defibrillation, which involves delivering an electric shock to the heart. Survival depends on how quickly the victim gets defibrillation, with chances of survival declining about 7 percent to 10 percent with every minute of delay. Few efforts to resuscitate succeed after 10 minutes.
What To Do
Maron and other physicians caution against ever hitting another person in the chest, no matter how lightly.
Or, visit the Web site of Operation Heartbeat, a community-based initiative of the American Heart Association aimed at improving the national survival rate from sudden cardiac arrest.
And for more on commotio cordis, try MomsTeam.com.