Q and A: What is Commotio Cordis?

Earlier this month tragedy struck the baseball field in Arizona when a 13-year-old Little Leaguer was trying to bunt and got hit in the chest. He took a few steps towards first and collapsed. He died the next morning.

Getting hit by a pitch is to be expected when playing baseball. Dying is not. The Arizona boy suffered from commotio cordis, which is Latin for agitation of the heart. Commotio cordis is a disruption of heart rhythm that occurs as a result of a blow to the area directly over the heart. From 1996 to spring 2007, the USA National Commotio Cordis registry had 188 cases recorded and fewer than 20 percent survived.

“It is a scary thing,” said Dr. Bruce Thomas, a seamheads contributor who practices sports medicine in Florida and was a consulting/Spring Training physician for the Florida Marlins from 1993-2002 and is currently in that role for the Washington Nationals. He is also Team Physician for the Brevard County Manatees, the Class A Affiliate for the Milwaukee Brewers.

Thomas said it is believed to be an electrical event and when the ball hits the right place during the right moment of the cardiac electric cycle it causes a sudden change in heart rhythm.

“Blood flow essentially stops. When it stops to the brain, in seconds, the patient becomes unconscious. When it stops elsewhere it results in rapid death,” he said.

I spoke with Thomas more about the condition.

Q: Why does the heart respond that way?A: Although the exact mechanism of what occurs is unknown, it is believed that sudden death is due to an electrical event, most likely ventricular fibrillation (VF) occurring immediately upon chest wall impact. Ventricular fibrillation is like a bowl full of worms wriggling. Not a coordinated synchronized beat like the normal heartbeat.

Q: Would it have mattered a split second or two later?A: That’s a very good question and the answer is unknown. It is, however, felt that the timing of impact of the blunt chest trauma is important in the mechanism of commotio cordis. There is only a 20 to 40 millisecond window on the up slope of what we call the T wave (early repolarization of the ventricles-lower chambers). This has been worked out through experimental models. Interestingly, the velocity also seems to be important, with higher velocities more likely to cause the event, as expected.

Q: Is the heart actually damaged or has it just stopped?A: For the most part, autopsy studies of these cases have shown a normal heart.

Q: Is a ball hitting someone’s chest similar to doing CPR (chest compressions) on someone with a beating heart?A: The velocity that’s required to cause commotio cordis is a minimum of 40 miles an hour. This is significantly higher impact then doing chest compressions during CPR on a normal heartbeat.

Q: Realistically, how hard does a ball have to hit someone to stop the heart?A: Although the answer to this question is also definitively unknown it appears that the ideal velocity to cause commotio cordis is 40 miles per hour. This explains why the vast majority of these cases occur in young persons (the mean age is 15 years old), and why 75 percent of cases have occurred during athletics involving blunt projectile such as baseball, lacrosse, and hockey.

Q: What’s the danger radius around the heart?A: Only impact occurring directly over the cardiac silhouette results in ventricular fibrillation, so it appears that the impact must occur directly over the heart.

Q: Why was this boy’s heart not able to be restarted as fast as it was stopped?A: If indeed this is caused by ventricular fibrillation, that rhythm usually requires intervention to revert back to a normal rhythm, and does not do so spontaneously. Because a heart in ventricular fibrillation does not pump blood normally, if at all, the person dies very rapidly without intervention such as an Automated External Defibrillator (AED).

Q: Cleary, seconds count, the next time this happens can a player be resuscitated?A: AEDs are more and more frequently seen at sporting events, and are required at most professional ball games. This may indeed allow us to resuscitate an athlete with commotio cordis, but the intervention would have to be done extremely promptly, and the rescue personnel would have to be fully trained in advance on the use of the device. That day may come.

Q: This type of tragedy seems to happen only in young players, are MLB players at risk?A: MLB players generally fall above the age range of most commotio cordis cases. We do know that younger patients are in the risk target zone and not older athletes.

Q: With your experience in the Major Leagues, do you know if protocols are in place if this were to happen? If so, what are they?A: All MLB trainers, positions, and some coaches are trained in CPR and AED use. We have protocols to ensure that the AEDs are working properly and we also have AED practice sessions and CPR review sections usually during spring training. If this were to occur during a Major League game, it would be handled the same as any other sudden loss of consciousness. With trained personnel and proper equipment very close at hand the likelihood of survival would be high.

Q: In your opinion what are the keys to preventing this tragedy?A: Unfortunately, and surprisingly, commercially available chest wall protectors have not been shown to effectively prevent commotio cordis. Many of the commotio cordis victims reported to the national commotio cordis registry were indeed wearing protective equipment at the time of their event. Coaching measures should encourage batters to turn away from oncoming projectiles whenever possible to avoid contact directly over the heart. Softer and less dense balls should be used whenever possible without changing the nature of the game. Age appropriate safety baseballs have indeed been shown to decrease the risk of commotio cordis.