Though it's not certain what sent Buffalo Bills defensive back Damar Hamlin into cardiac arrest, commotio cordis is usually sports-related, caused by a blow to the chest wall just outside the heart. Hamlin collapsed after he collided with a Bengals receiver during a tackle and appeared to take a hit in the head and chest. Hamlin stood up, took a few steps and fell backward. Medical personnel used CPR and an automated external defibrillator on Hamlin on the field for nearly 10 minutes and restored his heartbeat. He was taken by ambulance to the University of Cincinnati Medical Center, where he was in critical condition. Swipe to learn about the rare but potentially lethal heart disruption. Visit the link in bio for more.