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How an NFL hit could stop a heart

When Damar Hamlin’s heart stopped beating during a National Football League game between the Cincinnati Bengals and the Buffalo Bills on Monday night, the crowd fell silent.

Hamlin, a Bills safety, had taken a hit to the chest from the shoulder of a Bengals receiver in what appeared to be a routine play. After that he stood up, took a few steps, then fell onto his back, where he lay still.

According to reporting from the scenemanaged staff cardiopulmonary resuscitation (RCP) in the field and an automatic external defibrillator (an AED) was at his side. Invoice reps have confirmed his heart stopped – but was then restarted – in the field.

After several minutes, an ambulance pulled onto the field and transported Hamlin to the University of Cincinnati hospital, where he was in critical condition. starting Tuesday afternoon.

Injuries on the soccer field are more common than in any other popular professional sport: more than three times as many injuries happen during NFL games as it does during professional basketball, baseball, hockey and football games combined.

But when we think of soccer related injuries, the ones that usually come to mind are concussions and musculoskeletal problems. Heart injuries, not so much.

It is still unclear what happened to Hamlin during Monday night’s game. However, it is possible for the heart to stop beating after a sharp, aimed blow to the chest, an event called commotio cordis in medical terms, from the Latin for “agitation of the heart.” And while it’s a well-described sports injury, it’s not something most NFL viewers are familiar with.

That’s because commotio cordis is incredibly rare, said Mark Link, a cardiologist at the University of Texas Southwestern Medical Center. These types of injuries generally cause between 15 and 20 deaths each year.

And they’re especially rare in adults, Link said. “Typically, the average age is around 15, so Damar was a little old for that,” she said. Hamlin is 24 years old.

While the situation is still evolving, it’s worth understanding what this unusual condition is, who is most typically at risk, and how athletes, especially young athletes, can protect themselves.

Commotio cordis is an interruption of heart contractions and is fatal if not treated immediately

When a person’s heart stops beating after a chest injury, it’s usually because the blow was hard, focused, and located precisely enough to heart beating out of its usual rhythm. The lower chamber of the heart, whose rhythmic contractions normally drive the body’s blood circulation, simply vibrates in a disorganized way.

This leaves the injured person with no blood pressure and no circulation of oxygen-rich blood to the brain and the rest of the body’s organs. If circulation is not restored within minutes using CPR and an AED, oxygen starvation inevitably leads to death. The percussive motion of CPR circulates blood to the brain and organs as the heart falters and the AED returns the heart to a normal rhythm.

The impact does not necessarily injure—that is, bruise or otherwise damage—the heart muscle itself. This means that in the event of a commotio cordis, the heart should be able to function normally once the rhythm is restored. However, if the heart muscle has sustained damage, as might happen from a blow to the chest during an automobile accident, for example, the outcome could be more complicated, requiring more medical intervention and recovery time after the event.

Buffalo Bills players stand and kneel on football field.  An ambulance is visible in the photo.

Buffalo Bills players react after teammate Damar Hamlin was injured during the first quarter of the game against the Cincinnati Bengals on Jan. 2. Kirk Irwin/Getty Images

The rapid medical response Hamlin received on the field likely maximized his chances of a full recovery. “Resuscitation is possible if you’re ready with CPR and ready with an AED — and both appear to be the case” for Hamlin, Link said.

“This is a crucial learning from this point,” he said. “Everyone should be prepared for something like this to happen at sporting events.” This means having an AED nearby, as well as people trained to perform CPR (and recognize the need for it).

The condition is rare because it requires many factors to line up just like that

Athletes take a lot of blows to the chest, so why don’t we see more of this injury?

Several specific elements must line up simultaneously for a hard blow to the chest to lead to cardiac arrest.

Heart rhythms are only vulnerable to force disruption during a small window of time — during just 1 to 2 percent of the heart’s pumping cycle, Link said.

Furthermore, the impact must occur in a very specific place: just above the heart. The force of the impact must be large, and the object causing the impact must be small enough to concentrate a lot of force into a very small area, such as a baseball or lacrosse ball. (Although the larger size of footballs and soccer balls theoretically make them less likely to cause commotio cordis because they distribute force more widely, several recent relationships described the condition following a soccer ball impact to the chest.)

The condition is more common in younger athletes because their chest walls are usually thinner than those of adults, meaning their hearts are less protected from the force of any impact. That’s why, although the majority of cases reported each year involve young baseball players, Link has never heard of a case that occurred in professional baseball, much less professional basketball or football.

Prevention is possible… but unlikely to become standard in professional football

Again, it is rare for an adult athlete to have their heart stopped by an impact.

An emotion of the heart it’s rare even in youth sports, but when it happens the consequences are enormous. It is associated with such high mortality rates that chest protection is becoming the standard in a wide range of youth and young adult sports.

The national operating committee on standards for sports equipment has approved chest protectors which are now required by the National Collegiate Athletic Association for lacrosse goaltenders and from organization that governs US high school baseball for hunters. And while other sports or positions may not require this gear, interested players can definitely use it.

These items are unlikely to become mandatory for professional athletes because the risk of the event is much lower than for younger people, Link said. “The requirement for chest protection doesn’t make much sense to them because they are much less sensitive,” he said.

While what happened to Hamlin was shocking, Link said it’s important to see the event in context. Athletes are more likely to die from an automobile accident on the way to the field than from being hit in the chest during a game.

“Sports are great for kids and they should keep playing them and wearing seat belts while exercising,” she said.

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Buffalo Bills safety Damar Hamlin chases Tee Higgins of the Cincinnati Bengals in the first quarter of the game at Paycor Stadium in Cincinnati, Ohio on January 2. Dylan Buell/Getty Images