It's possible that the hard tackle received by Damar Hamlin triggered a rare condition that led to his cardiac arrest, experts said in the wake of his startling collapse on Monday night.
Hamlin, 24, who plays for the Buffalo Bills, collapsed on the field during a game after tackling the Cincinnati Bengals player Tee Higgins.
Higgins collided hard with Hamlin's chest, striking with his right shoulder around where Hamlin's heart would be. After initially getting up, Hamlin collapsed and was rushed to the hospital.
Though it's too soon to know exactly what happened with Hamlin, medical experts laid out some possibilities based on what they saw.
They said this kind of strong impact to the chest could cause commotio cordis, a rare but life-threatening condition that can occur if the heart is struck in a very precise window of its beating.
Gregory Marcus, a cardiologist and professor of medicine at the University of California at San Francisco, described the condition to The Washington Post.
You must be extremely unlucky to get commotio cordis — Marcus said it happens when the chest is hit at a very specific moment of the heartbeat, in a 40-millisecond window.
Even a heavy impact like that from a football player (Higgins is 219 pounds and was running fast) is unlikely to directly damage the heart inside the rib cage. But it can cause an irregular surge of electricity, which can lead to sudden cardiac arrest even in those without preexisting heart issues.
Commotio cordis has mostly been reported among adolescents, but some cases have been reported among people over 20.
In an interview with the Boston TV station WCVB, Brien Barnewolt, an emergency-room doctor at Tufts Medical Center, also mentioned commotio cordis as a possibility.
Marcus and other experts cautioned that it's impossible to know what happened to Hamlin without seeing his medical records, which have not been released by the league or the hospital.
It's also possible that Hamlin had an underlying condition that had gone unnoticed.
The Sports Institute has suggested that undiagnosed underlying conditions are a main cause of sudden cardiac arrest in young athletes.
Chuck Hughes, the only player to die during an NFL game, collapsed in 1971 and was later found to have atherosclerosis, a clogged artery.
Marcus told The Post that a blow to the chest could also cause an aneurysm, exacerbating an undetected heart defect. Rajesh Dash, an associate professor in cardiovascular medicine at Stanford University, gave The Post a similar assessment.
The blow to Hamlin did not immediately seem dangerous. Ted Johnson, a former New England Patriots player, told WCVB that the play didn't seem to break any rules or be unusually violent.
After the tackle, Hamlin got up and adjusted his helmet. Then he collapsed and lay motionless, in cardiac arrest. Shocked teammates, some in tears, surrounded Hamlin as he received CPR. He was later rushed to the hospital.
The Bills said early Tuesday that Hamlin was in critical condition.
Barnewolt said Hamlin could recover if he got good care straight away. "I think the important thing is the quality of CPR and the timing of any kind of resuscitative efforts or defibrillation efforts that occur," he told WCVB.
"The sooner the better, obviously," he added. "People have been known to have great outcomes, even with prolonged cardiac arrest, if the resuscitative efforts are of high quality."
Correction: January 3, 2022 — An earlier version of this story misspelled Damar Hamlin's name as Hamil.
