NEW ORLEANS — There is a "Pray for Damar" sign at the Bills’ stadium today.
The team says Hamlin spent the night in intensive care and remains there today in critical condition.
So, what happened to his heart?
It was a heart-stopping moment for millions as they watched the Buffalo Bills' medical team perform CPR on the field to safety Damar Hamlin. Medics also brought an automated defibrillator to his side. So, what may have happened to the 24-year-old football player in Monday night's game?
We turned to Tulane Cardiac electrophysiologist Dr. Eoin Donnellan. He has not treated Hamlin, but is an expert in the field. Signs point to sudden cardiac arrest when the heart suddenly loses its normal rhythm and stops pumping blood.
“Immediately following blunt upper chest trauma would be highly suspicious for this condition,” Dr. Donnellan said.
In a normal heartbeat, electricity is sent through the heart, making the four chambers squeeze and release or pump in a precise rhythm. That moves the blood from one chamber to the next to pick up oxygen from the lungs and spread it around the body through the blood.
Now, if there is an interruption right in the recovery period when the electricity pauses for just 1/5 to 1/2 of a second, it throws off the coordination, the rhythm, and the two big chambers at the bottom just wiggle and don't pump.
“During the initial phase of that recovery period, if either a blunt trauma occurs or a premature beat, it sets in motion ventricular fibrillation,” he said.
The only way to get the heart rhythm back is to shock it with paddles or an AED, automated external defibrillator. CPR helps circulate the blood until that rhythm is restored. Reports are that Hamlin's vitals were normal in the hospital Monday and that CPR was started fast on the field.
“I think it's a promising sign,” Dr. Donnellan said. “The quicker the return of spontaneous circulation occurs, the more likely the person is to have a better outcome.”
Doctors are likely checking to see if there was an undiagnosed problem with the heart structure or electricity from birth that caused the sudden cardiac arrest. If there isn't, and it was only from the hit, that is called commotio cordis.
It's rare, with only 30 cases a year, mostly in young boys hit by a baseball or hockey puck in the chest. Now the question for Hamlin is: Was there any organ damage, especially brain damage, when his heart was not pumping?
If there is an underlying condition, he may need an implanted defibrillator. If not, and it was just from the hit, it is likely he would recover.
The only NFL player to die on the field was in 1971. Detroit Lions wide receiver Chuck Hughes, at 28, had a heart attack, but it was from a clot from a clogged artery.