Buffalo safety Damar Hamlin, 24, collapses on the field in a game against Cincinnati

ROB SCHMITZ, HOST:

Buffalo Bills safety Damar Hamlin is in critical condition after collapsing on the field during last night's game against the Cincinnati Bengals. In a statement, the Bills said Hamlin suffered a cardiac arrest following a hit. They said his heartbeat was restored on the field, and he was taken to a hospital for further testing and treatment. Joining us now to talk about what happened is Dr. Christopher Madias. He's the director of the Cardiac Arrhythmia Center at Tufts Medical Center. Hello, Dr. Madias.

CHRISTOPHER MADIAS: Good morning, Rob. How are you?

SCHMITZ: I'm well. Thank you. What can you tell us about the role that the blow to Hamlin's body may have played in the cardiac arrest? And how often does this sort of thing happen?

MADIAS: Yeah. You know, I'm speculating, but this looked to be what's called commotio cordis, which is a blunt chest blow to the chest that can induce dangerous, life-threatening heart rhythm (ph), cardiac arrest. And this is a rare event that occurs most commonly in the setting of sport, most commonly in sports that involve blunt projectiles that impact the chest wall, such as baseball, hockey, lacrosse. It's rare in football, and it's rare because it's really - it has to be a perfect storm of events where there is an impact to the chest wall overlying the heart with just enough force, and what's most critical is the timing. 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. And because of that, it's such a rare event. Again, about 20 to 30 cases are reported per year.

SCHMITZ: Twenty to 30 cases per year. You know, it's important to remind people here that we're speculating about what happened to Hamlin. Doctors have not yet released more detailed information about the cause of his cardiac arrest. Are there any other possibilities that could have caused this besides commotio cordis?

MADIAS: There are. There are definitely other possibilities. You know, did he have an underlying heart condition that might have led to this? But presumably not. You know, presumably, this was a healthy professional athlete. And again, it was just the perfect storm of unfortunate circumstances that led to this.

SCHMITZ: Now, CPR was performed on Hamlin immediately after he collapsed. How important were those first few seconds? And how significant are these next several hours for him?

MADIAS: You know, those first few minutes were critically important. The biggest issue with survivability of sudden cardiac arrest, you know, sudden arrhythmic arrest is how quickly CPR and, even more importantly, defibrillation can be initiated. Hopefully this was recognized quickly on the field, and it appeared it was. And quick CPR was delivered to the player, and from what I understand, defibrillation was also delivered, and a normal pulse was eventually achieved.

SCHMITZ: And given what we know, how likely is a full recovery?

MADIAS: You know, hard to tell. You know, time will tell. The good - you know, what is - what he has in his favor is that, again, he's a young man and presumably a very healthy young man, and CPR and defibrillation were initiated urgently. Those are all aspects that could lead to a potential full recovery.

SCHMITZ: And, you know, watching the replay - really quickly here - this seemed like a routine tackle in the NFL. Is there something more that the NFL could do to prevent these types of hits?

MADIAS: You know, these are rare, you know, really rare events. I'm not aware of any particular events that the NFL is looking at to prevent. In youth sports, there have been studies looking at protective equipment, protective chest protectors. But again, these are such rare events that I'm not aware of anything that the NFL's looking at to prevent this.

SCHMITZ: That that's Dr. Christopher Madias. Thank you so much.

MADIAS: Thank you for having me. Transcript provided by NPR, Copyright NPR.