Did Damar Hamlin experience commotio cordis? What to know about the rare phenomenon

In the three weeks since Buffalo Bills safety Damar Hamlin suffered cardiac arrest after making a tackle during a Jan. 2 nationally televised game against the Cincinnati Bengals, his remarkably fast ongoing recovery has heartened the nation — whether you closely follow football or not.

Hamlin spent nine days hospitalized in Cincinnati and Buffalo medical centers before he was discharged on Jan. 11.

And while his doctors have not disclosed what they believe was the cause of Hamlin’s heart stoppage, in the hours immediately following the incident, medical experts were confidently speculating on ESPN and cable news networks that Hamlin had suffered an incredibly rare phenomenon: commotio cordis.

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What is commotio cordis?

In a properly functioning heart, the organ pumps oxygen-rich blood throughout the body every 8/10ths of a second. There is a rhythm to the process and the heartbeat itself has an electrical cycle that keeps the blood flowing at a healthy pace.

However, there is an infinitesimally tiny window during this cycle — just milliseconds — when the heartbeat is vulnerable to disruption (i.e., fibrillation) if a strong enough force is applied to the left chest wall.

"It has to be a perfect storm of events where there's an impact to the chest wall overlying the heart with just enough force, and what's most critical is the timing," said Dr. Christopher Madias, the director of the New England Cardiac Arrhythmia Center at Tufts Medical Center, in an interview with NPR the day after the incident. "It happens within a critical period within the cardiac cycle. We're talking about 20 to 30 milliseconds within the cardiac cycle that the heart is vulnerable to this."

To give you an idea of how tiny this window is: A millisecond is 1/1,000^th of a second.

In a Washington Post article, Mark Link, a professor of internal medicine and director of cardiac electrophysiology at the University of Texas Southwestern Medical Center, explained “with commotio, the way it causes sudden cardiac arrest is there are a number of variables that have to be perfect. Probably the most important is timing … [and] it has to be directly over the heart, it can’t even be 2 centimeters away.”

In addition, noted Link, other factors include the shape, size and force of the striking object — which “can’t be too much, can’t be too little.”

How rare is this phenomenon?

In 2010, the New England Journal of Medicine published an article in which it stated the National Commotio Cordis Registry reported 224 cases between 1995 and 2010 — in other words, fewer than 20 annually (although the article concedes many cases also probably went unreported). Even now, most experts estimate that there are no more than two dozen to three dozen instances per year.

Around half of the cases occur in youth sports to athletes between the ages of 10 and 18 — and especially sports in which a projectile like a baseball, lacrosse ball or hockey puck can travel at a high rate of speed.

Because of the aforementioned specificity of conditions necessary for commotio cordis to occur, it’s almost unheard-of for it to happen during a football game or any other collision between two adult athletes.

In addition, most of these cases occur in youth sports, experts believe, because the skeletal systems of younger athletes are not fully developed. Their chest walls are thinner and more pliable than those of adults.

However, that doesn’t mean it can’t happen under the right circumstances to professional athletes.

It happened to an NHL Hall of Famer in 1998.

St. Louis Blues star Chris Pronger, then 23, took a puck to the chest during the Stanley Cup playoffs. He collapsed to the ice and lost consciousness for between 20 and 30 seconds — but his heart quickly started beating again on its own so he didn’t require CPR. After it was determined he suffered no lasting damage, he was back on the ice again two nights later.

Importance of CPR and automated external defibrillators

What the Hamlin injury has highlighted is the life-and-death importance of knowing how to perform CPR and having immediate access to an automated external defibrillator (AED) for anyone who goes into cardiac arrest.

Annually some 350,000 Americans go into cardiac arrest outside of a healthcare setting — and only an estimated 10% of them survive and fully recover.

But experts stress that those who receive immediate basic lifesaving treatment — i.e., CPR and defibrillation — have greatly enhanced odds.

In the days after Hamlin’s collapse, the American Heart Association said it saw a 200% increase in web traffic to its CPR site.

And that’s especially good news considering a  2018 survey by Cleveland Clinic found that while 54% of Americans said they knew how to perform CPR, only 11% knew the correct pacing for performing chest compressions (100 to 120 beats per minute). Likewise, a survey published in a 2017 edition of the Journal of the American Heart Association found that just 18% of people are up to date on their CPR training.

Before his injury, Hamlin’s Chasing M’s charitable foundation started a GoFundMe account in order to provide toys for kids in his native Pittsburgh, Pa. The goal was to raise $2,500.

In the days following his injury, the account received some $8.9 million in donations.

Earlier this month, it was reported that Hamlin is planning to partner with the Giving Back Fund, which helps nonprofits manage their giving, and hopes to use the funds to “support young people through education and sports.”

Perhaps some of those resources will also help fund nationwide CPR and AED training.

If you’re interested in taking CPR/AED training, the Red Cross offers both in-person and online classes. Visit redcross.org to learn more.

This article originally appeared on Palm Beach Post: Buffalo Bills Damar Hamlin cardiac arrest may be commotio cordis