It has been one week since Bills safety Damar Hamlin collapsed on the field due to cardiac arrest.

Medical staff at the University of Cincinnati Medical Center say CPR helped save his life.

Annette Adamczak, a volunteer with the American Heart Association, says sudden cardiac arrest is when the heart abruptly stops. She says a heart attack is when something in the heart isn’t working properly.

According to Adamczak, when a heart attack turns into cardiac arrest and the person becomes unresponsive, that’s when you need CPR.

"The first thing you need to do is you need to check for responsiveness," said Adamczak. "You tap a person on the shoulder and say 'hey, are you OK?' If they don't respond, then you put your head down and you listen and then you watch the chest rise and fall. If it does not, and you're only looking for like 10 seconds, that's when you begin to do compressions."

Adamczak provided more information about CPR and the use of an automated external defibrillator.