Dr. Barry Maron was watching the Monday night game between the Buffalo Bills and Cincinnati Bengals when he saw Damar Hamlin absorb a hit, rise and collapse. Everything about the injury immediately suggested commotio cordis, he said.
"Clinically it seemed classic because there was the chest blow and then for five seconds or so he tolerated the arrhythmia that followed. That's what usually happens," Maron said.
Maron, a cardiologist at Lahey Hospital & Medical Center in Burlington, Massachusetts, is considered one of the world's top researchers on the subject. With the help of Maron and other research, here are some key questions and answers about the injury Hamlin suffered, which appears consistent with commotio cordis, and what it means for his health:
What is commotio cordis?
Commotio cordis is a rare but dangerous injury to the heart that causes cardiac arrest, and in many cases, death. Unlike most cases of sudden cardiac arrest, commotio cordis is not the result of a preexisting condition. "The astounding thing about commotio cordis is that it's a blow that's timed exactly to a 30-millisecond window" during the heartbeat, Maron said. "Very few blows will be timed that way. It's just the luck of the draw."
The National Institutes of Health reports that there are typically fewer than 30 cases nationwide every year.
Such a blow to the chest -- most commonly from a thrown or batted ball or puck -- can disrupt the heart's rhythm, causing what is known as ventricular fibrillation. It is common for people who have suffered such a blow to remain conscious and mobile for a few seconds before they lose consciousness, as Hamlin did before he collapsed Monday night. When someone suffers such a blow, Maron and others say, it is crucial to apply a defibrillator to the patient as quickly as possible. More than half can be revived without permanent injury, he said. But it's vital to restore blood flow to get oxygen to the brain and organs.
How is commotio cordis different from other heart issues?
High-profile cardiac deaths in sports are usually the result of heart disease or drug use, not injury. Some, such as G League basketball player Zeke Upshaw, suffered from an undiagnosed genetic disease known as hypertrophic cardiomyopathy, a thickening of the heart muscle. Others, such NFL player Chuck Hughes, who died on the field in 1971, had undiagnosed coronary disease.
But with commotio cordis, there is no disease and nothing to detect before it occurs. It is simply an injury with exceptionally bad timing.
There have been a handful of recorded cases in youth and high school football, and researchers believe that younger athletes are at greater risk because of their underdeveloped ribcages.
What is the biggest danger to Damar Hamlin right now?
The problem now might not be his heart, but rather how much damage Hamlin's brain and organs might have suffered while they were deprived of oxygen.
According to Maron and other experts, time is the crucial factor, and the fact that Hamlin needed resuscitation for multiple minutes is troubling. (Hamlin received oxygen, according to the ESPN broadcast, as he was placed in the ambulance and taken off the field some 16 minutes after he collapsed. He then was driven to the hospital.)
Typically if the brain is deprived of oxygen for more than five minutes, it can suffer permanent injury and a patient could suffer multiple organ failure. The treatment Hamlin is reportedly receiving, lowering his body temperature, is consistent with protocols to preserve the brain and organs.
How common is commotio cordis in football?
Commotio cordis is rare to begin with, but it almost never occurs in football because of the padding players wear. Typically commotio cordis is caused by a direct, forceful and unprotected blow to the heart, such as a thrown or batted baseball, softball or hockey puck. Padding diffuses the energy of that blow.