Cardiac arrest in healthy athletes: Colorado heart expert explains how it can happen

COLORADO SPRINGS, Colo. (KRDO) -- Many people are wondering how a pro football player who's young, in top physical condition and wearing protective equipment, can suddenly experience cardiac arrest and be in critical condition after seemingly-minor contact while tackling another player.

That's the common question being asked by the public Tuesday about Buffalo Bills safety Damar Hamlin, 24, who collapsed shortly after tackling a Cincinnati Bengals player on Monday Night Football.

Cardiac arrest in athletes has happened in a variety of sports at all levels, from football to baseball and even lacrosse; often in such cases, a blow to the chest -- from a ball. a piece of equipment or physical contact -- can trigger cardiac arrest.

According to media reports, Hamlin was tackling a Bengals wide receiver when he was hit in the chest by the receiver's shoulder; Hamlin quickly rose but collapsed after several seconds.

Hamlin's heart reportedly stopped beating momentarily but was restored by medics who performed CPR and administered oxygen to Hamlin; as of Tuesday morning, he was listed in critical condition at a Cincinnati hospital.

However, Dr. Wendy Tzou, medical director at UCHealth University of Colorado Hospital in Denver, said that a blow to the chest causing cardiac arrest -- a condition known as commotio cordis -- is rare and unlikely to have stopped Hamlin's heart because the blow would have had to happen at a specific time during his heartbeat cycle.

"The fact that he stood up for a few seconds before collapsing, tells me commotio cordis was a feasible but not probable cause," she explained. "The most common cases of heart-related deaths in athletes are genetic conditions that they were born with, weren't screened for or weren't found in a screening."

One of those conditions, she said, is hypertrophic cardiomyopathy.

"That's where the heart cells kind of form abnormally and predisposes to issues with respect to the function of the heart, as well as electrical disturbances," she said. "In the general population, it occurs in about one in 200."

Another condition, congenital malformation, is a defect in blood flow to the heart, Tzou said.

The doctor said that the genetic conditions can cause cardiac arrest while an athlete is competing or training.

“And it may even be in the midst of peak activity or recovery from exertion," she stated. "The elevated adrenaline in that setting, the increased work of the heart in that setting.”

Hamlin's cardiac arrest has many parents wondering if their kids are at similar risk by playing contact sports; she said that parents should avoid overly-screening their kids unless they are world-class, top varsity or professional athletes.

"You'd get far more anxiety out of it than you would find a condition," she said. "My hope is that parents won't discourage their kids from playing sports. But they can ensure that kids have the proper instruction and equipment. There's risk in everything we do. W're doing our best to identify that risk."

Tzou said that she and her husband watched the game with their son, 9, and their daughter, 11.

"They didn't exactly know what was happening," she recalled. "My husband and I obviously did. They were confused and had a lot of the same questions that we're talking about now -- like how could this happen, specifically, to someone who is otherwise healthy?"

Finally, Tzou said that Hamlin receiving medical care immediately should bode well for his recovery.

"To prevent lasting brain and organ damage, you need to perform CPR and use a defibrillator with therapy within four minutes," she said."