WEDNESDAY, Jan. 4, 2023 (HealthDay News) -- Damar Hamlin, the Buffalo Bills player who collapsed Monday after suffering cardiac arrest during a game, is showing “signs of improvement,” his team said Wednesday.

Still, the 24-year-old "is expected to remain under intensive care as his health care team continues to monitor and treat him,” the Buffalo Bills tweeted.

Meanwhile, Hamlin's uncle, Dorian Glenn, said Tuesday night that his nephew’s heart stopped both on the field and again at the hospital, where “they had to hit him with the defibrillator."

The player has lung damage and can’t breathe on his own, Glenn said. He is receiving 50% oxygen, down from 100%, CBS News reported.

CBS News medical contributor Dr. David Agus suggested that Hamlin may have experienced “commotio cordis,” a heart arrhythmia that happens with a direct blow to the chest, though that has not been confirmed.

It’s the type of injury that causes a “confusion of the heart,” and is experienced by about 30 people in the United States each year, including Little League players who get hit in the chest with a ball, CBS News reported.

Getting hit can interfere with the heart’s electrical signals, causing an erratic heartbeat that doesn’t send blood to the brain.

"That's why there are defibrillators on the sidelines of games, is to be able to use them to shock the best heart back into a regular rhythm," Agus said.

The NFL suspended the game after Hamlin was injured and has not rescheduled it yet.

"It's certainly not an exaggeration to say that the skilled and immediate response by these talented caregivers prevented a tragic outcome," NFL Chief Medical Officer Dr. Allen Sills said Wednesday, CBS News reported.

Fans and sports teams have since shown their support for Hamlin, including all 32 NFL teams changing their Twitter profile pictures to Hamlin’s No. 3 jersey. Those photos also say, “Pray For Damar.”

Niagara Falls was lit red to honor the player, while people in Western New York put red and blue lightbulbs outside their homes. Fans gathered outside Highmark Stadium Tuesday for a vigil, CBS News reported.

"People who don't even know us are showing love and support and we're so thankful for that," Glenn said. "I know those prayers are helping because he's definitely recovering ... God got a mission for him and that's why he's still here."

More information

The U.S. National Library of Medicine has more on commotio cordis.

SOURCE: CBS News