After Buffalo Bills’ player Damar Hamlin collapsed Monday during a game, cardiology and sports medicine specialists emphasized he is alive because people knew to quickly give chest compressions to keep his blood circulating and shock his heart into a normal beat.

League officials said Hamlin suffered cardiac arrest, a catch-all term for when the heart stops beating suddenly. About 90% of people who have it outside of a hospital die because they don’t get CPR and defibrillation fast enough.

“CPR is what gives doctors the opportunity to figure out what is underneath the cardiac arrest so they can figure out appropriate treatment,” said Dr. Stacy Fisher, Johns Hopkins Medicine cardiologist and a member of the American Heart Association Greater Maryland Board of Directors.

“The wonderful thing was that he was given immediate CPR on the field and that the first responders knew how.”

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There has been a push in recent years to ensure many more people in Maryland and around the country learn how to provide cardiopulmonary resuscitation, or CPR, with their own hands or with a machine.

There also has been an effort to place devices automated external defibrillators, or AEDs, in public places, including sports venues and fields, as well as shopping malls and airports.

All Maryland public schools must have AEDs and individuals trained to use them, including at all school-sponsored athletic events. As of last year, they have to have specific action plans to treat cardiac arrest and other life-threatening conditions.

Fisher noted that in Maryland, students also are required to learn CPR to graduate from high school. Breanna’s Law took effect for students entering ninth grade in 2015 and includes hands-on training in CPR and using an AED.

Breanna Sudano was a Perry Hall High School freshman field hockey player in 2011 who suffered cardiac arrest on the field but was saved by bystanders who performed CPR until an AED was located and administered. According to media reports at the time, she became an advocate for the training.

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“That provides something like 60,000 new first responders every year if everyone learns,” Fisher said.

Fisher and others said everyone saw Hamlin get hit, but it’s still hard to speculate on what caused Hamlin’s cardiac arrest without more information. Statements from the Bills and the NFL have said he remains in critical condition.

One possible condition is called commotio cordis, when the heart suffers a blow at a specific time in the heart beat cycle, causing it to stop beating. The often-fatal condition is most often seen in athletes, especially baseball and lacrosse players, because the balls make perfect projectiles.

USA Lacrosse Magazine reported a case of commotio cordis in Maryland last year at Loyola Blakefield. Freshman Peter Laake was hit in the chest by a shot but was quickly revived with the use of an AED carried by the team’s athletic trainer.

Fisher noted, unlike the Laake case, that it appeared to take a long time to revive Hamlin. That would be unusual for the condition, though the length of the actual delay wasn’t clear.

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Any delay could have been because Hamlin was wearing layers of padding that had to be removed before he was treated, said Dr. Scott D. Jerome, an assistant professor of medicine at the University of Maryland School of Medicine and co-director of Sports Cardiology at the University of Maryland Medical Center.

Jerome said all the padding, plus the bulkiness of many professional football players, can protect players like Hamlin. It’s more often seen in younger athletes than Hamlin, who is 24, or less developed athletes.

There have been only about 300 cases of commotio cardis reported since the 1990s, Jerome said, but it likely happens far more often. That also has prompted some leagues to require changes.

“Since it’s become a known condition, little leagues are taking precautions such as making baseballs a little softer and requiring more chest protection,” Jerome said.

If Hamlin has commotio cardis and the treatment was prompt enough, he could recover and potentially continue playing professional sports, Jerome said. He could have more long-term consequences if there was significant delay and his brain was deprived of oxygen for more than three minutes or if he suffered other heart damage.

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But Jerome and others emphasized that they don’t know what condition Hamlin has or the damage done.

Cardiac arrest can also be caused by underlying health conditions not identified in extensive screening for pro athletes, which normally includes medical exams and information about family history of disease and any other medical events on or off the field.

But that may not uncover a vulnerability that surfaces only under certain circumstances. Another possible cause of the cardiac arrest could be another traumatic injury such as a tear in a major blood vessel.

Hamlin could potentially recover from any of these events, though he could require more treatment for the underlying condition and damage during the cardiac arrest, said Dr. Ankit B. Shah, a sports cardiologist at MedStar Heart & Vascular Institute and director of MedStar Sports & Performance Cardiology.

Shah also said returning to sports would require a conversation about his and his family’s tolerance for more risk.

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More immediately, Shah said the takeaway from the event should be that CPR and use of an AED gave him the chance to live. He said more people should seek training, and parents, schools and leagues should insist others around students and athletes be trained and have equipment and action plans.

“Cardiac arrest in athletes happens rarely, but those on the field and those of us in the medical community need to be prepared for when it happens,” said Shah, also an assistant professor of medicine at Georgetown University Medical Center.

“All the coaches and athletic trainers need to be trained and ready, and not one guy who is a 10-minute jog away,” he said. “If a shock to the heart is most important, then the AED can’t be in the nurse’s office that is locked at night and on weekends.”

Others should learn CPR whether they have an athlete in the family or not, said Dr. Panagis Galiatsatos, an assistant professor in the Johns Hopkins’ Division of Pulmonary & Critical Care Medicine.

He is teaching a CPR class Jan. 7 at the Mack Lewis Boxing Gym in East Baltimore, planned three months ago.

“A cardiac arrest can strike anyone at any time, and to have the best chance of surviving when your heart stops we are at the mercy of someone else to administer CPR,” he said.

“Knowing CPR is a skill that is literally life-saving,” he said. “Knowing how to administer CPR and use an AED properly should be a priority of public health for all.”

Meredith Cohn is a health and medicine reporter for The Baltimore Banner, covering the latest research, public health developments and other news. She has been covering the beat in Baltimore for more than two decades.

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