clock menu more-arrow no yes mobile

Filed under:

How an NFL hit could stop a heart

Damar Hamlin collapsed on the field Monday night. It’s rare, but a direct hit can cause cardiac arrest.

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
Keren Landman, MD is a senior reporter covering public health, emerging infectious diseases, the health workforce, and health justice at Vox. Keren is trained as a physician, researcher, and epidemiologist and has served as a disease detective at the US Centers for Disease Control and Prevention.

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 went silent.

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

According to reporting from the scene, personnel administered cardiopulmonary resuscitation (CPR) on the field, and an automatic external defibrillator (an AED) was at his side. Bills representatives have confirmed his heart stopped — but was then restarted — on the field.

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

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

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

It’s still unclear what happened to Hamlin during Monday night’s game. However, it is possible for the heart to stop beating after a hard, focused hit 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 uncommon, 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 particularly rare in adults, Link said. “Typically, the mean age is around 15, so Damar was a little bit old for this,” he said. Hamlin is 24.

Although the situation is still evolving, it’s worth understanding what this unusual condition is, who’s more typically at risk, and how athletes — especially young athletes — can keep themselves safe.

Commotio cordis is a disruption of the heart’s contractions — and it’s deadly 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 precisely enough located to knock the heart out of its usual rhythm. The lower chamber of the heart, whose rhythmic contractions normally drive the body’s blood circulation, just quivers in a disorganized way.

That 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 a matter of minutes using CPR and an AED, that oxygen starvation inevitably leads to death. The percussive motion of CPR circulates blood to the brain and organs while the heart is faltering, and the AED shocks the heart back into restoring a normal rhythm.

The impact doesn’t necessarily injure — that is, bruise or otherwise damage — the heart muscle itself. That means that in the event of commotio cordis, the heart should be able to resume function normally once its rhythm is restored. However, if the heart muscle did sustain damage — as it might from a chest blow during a car crash, for example — the outcome may be more complicated, requiring more medical intervention and recuperation time following the event.

Buffalo Bills players stand and kneel on the 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 January 2.
Kirk Irwin/Getty Images

The quick medical response Hamlin received on the field likely optimized his chance of a full recovery. “Resuscitation is possible if you’re prompt with CPR and prompt with an AED — and both of those things appeared to be the case” for Hamlin, said Link.

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

The condition is uncommon because it requires a lot of factors to align just so

Athletes take lots 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 thump on the chest to lead to cardiac arrest.

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

Additionally, the impact needs to take place in a very specific place: just over the heart. The force of the impact needs to be substantial, and the object delivering the impact needs to be small enough to concentrate a lot of force in a very small area, like a baseball or a lacrosse ball. (Although the larger size of footballs and soccer balls makes them theoretically less likely to cause commotio cordis because they distribute force more widely, several recent reports have described the condition following chest impact from a soccer ball.)

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

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

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

Commotio cordis is also rare in youth sports — but when it happens, the consequences are enormous. It’s associated with such high death rates that chest protection is now becoming the standard across a range of youth and young adult sports.

The National Operating Committee on Standards for Athletic Equipment has approved chest protectors that are now mandated by the National Collegiate Athletic Association for lacrosse goalies and by the organization that governs US high school baseball for catchers. And while other sports or positions may not mandate this gear, players who are concerned can certainly use it.

It’s unlikely these items will become mandated for professional athletes because the risk of the event is so much lower than it is among youth, said Link. “Mandating chest protection for them doesn’t make as much sense because they’re just so much less susceptible,” he said.

Although what happened to Hamlin was shocking, Link said it’s important to view the event in context. Athletes are more likely to die of a motor vehicle accident on their way to the field than they are of being struck in the chest during a game.

“Sports are great for kids and they should continue to play them — and wear their seat belts on their way to practice,” he said.

Sign up for the newsletter Today, Explained

Understand the world with a daily explainer plus the most compelling stories of the day.