Tyler Adams, left, consoles Georgetown forward Aaron Bowen near the end of the second half of the Hoyas’ loss to Villanova. (Toni L. Sandys/The Washington Post)

Georgetown Coach John Thompson III gathered his men’s basketball team after practice Thursday afternoon, ready to share a secret. Two days before senior day at Verizon Center, Thompson told his players he didn’t believe in the standard tradition of starting seniors in their final home game and that all of the Hoyas seniors already had started at some point this season, anyway.

And then the coach paused and turned to Tyler Adams.

“But we’re going to make an exception for Tyler,” Thompson said. “You’re starting.”

Smiles spread over every player. The words stunned Adams; he wondered whether his coach was joking. Thompson was serious: Adams, a Georgetown senior sidelined for almost the entirety of his career by a heart condition, will start Saturday against Seton Hall. Adams will play one possession or so, the highlight of a career snatched from him four games into his freshman season.

“I had no idea,” Adams said Friday afternoon. “He kind of surprised us with it.”

Adams remained part of the team through a medical hardship waiver, which allowed him to attend Georgetown while not counting against the team’s scholarship limit. Georgetown obtained an NCAA waiver for him to appear Saturday, a process Thompson began 16 months ago to honor a player who turned from teammate to assistant coach, who remained a positive influence even through cruel fate.

“Coming in, he was going to be the next Georgetown center,” Thompson said. “It hurt him. It hurt us. But he’s someone that has not pouted. He’s someone that has found a way to help this team, to make his teammates better in a totally different way than what any of us envisioned. We just wanted to give him a chance to get back out there.”

Saturday’s brief playing time will be Adams’s first action since Dec. 3, 2011, when he played 11 minutes in a blowout victory. After originally committing to Duke, he arrived at Georgetown from Brandon, Miss. as part of a ballyhooed recruiting class alongside current Washington Wizards player Otto Porter Jr.

“I knew how great of a player he was,” said senior forward Mikael Hopkins, who has known Adams since he was 13.

Adams was born with an irregular heartbeat, and at age 6, he underwent an operation to remove a muscle from his heart. But he never experienced any heart problems until age 18. During summer workouts at Georgetown before his freshman season, his heart would not beat fast enough during strenuous exercise. He had a pacemaker implanted, and things were normal again from July through December 2011.

Fifteen minutes into practice on Dec. 14, 2011 — a date engrained in Adams’s memory — he felt chest pains and told a trainer he needed to go to the hospital. Doctors diagnosed an arrhythmia, which does not guarantee harm but greatly enhances the odds of a potentially life-threatening heart issue.

“The doctor told me I could play 20 years and nothing happens,” Adams said. “Or I could play two minutes and something happens.”

Doctors provided information and left the choice to Adams. He consulted with his parents and Thompson. His parents, Lonnie and Darlene, pushed for him to play. At first, Adams wanted to take the risk, too.

Thompson relented. He didn’t want Adams to risk his health, but he still offered to keep Adams on scholarship. Thompson had told him during his recruitment that if, God forbid, something took away basketball, Georgetown would be the school he wanted to graduate from. Now he would keep that word.

Smaller schools promised to clear Adams to play, and he could have left school to stay on the court. He discussed and debated his choice for a month. He decided he would stay. He decided he would never play again.

“You can’t trade a Georgetown degree for nothing,” Adams said.

For two or three games, Adams felt the sting of losing basketball. But for no longer. He dove into his new responsibilities: part manager, part cheerleader, part coach. He accepted he could neither change nor control his health, and he focused on how he could help his team.

“I’m really not a person who mourns when bad things happen,” Adams said. “I didn’t want to be that little, sad puppy on the team, not bringing positive energy. I know there’s people in life who have worse issues than I have.”

His disposition saved him from misery. Adams came to college with a realistic view of his future and self-awareness beyond his years. Even in high school, he wanted to coach after he finished playing, and he never fooled himself into how long that career would last.

“Most guys think they’re going to the NBA,” Adams said. “I was kind of real with myself. I was a 6-9 center. I was thinking, ‘There aren’t many 6-9 centers who can’t jump like Blake Griffin who are in the NBA.’ I wasn’t that athletic.”

Adams amazed teammates with how quickly he overcame his fate. At first, he became the team’s loudest supporter from the bench during games. At practice, he wiped sweat off the floor and rebounded as teammates took extra shots.

As his career passed, Thompson encouraged Adams to act more like a coach. Adams wore a crisp suit to games and whispered tips into players’ ears. Thompson told him to watch more film than anyone on the team. He asked for Adams’s insight when he prepared scouting reports. Adams focused on big men, and both Hopkins and Joshua Smith credited him for helping develop post moves.

More than that, Adams lifted the team’s spirit. He never bemoaned his rotten luck, so how could anyone complain about his own situation?

“When people get down on themselves, he’s always there to bring people up,” senior Aaron Bowen said. “There will be times when I’ll be down, and he’ll be in my ear saying, ‘Stay with it. Stay focused.’ He’s the man.”

Smith learned about Adams’s senior day start before any Georgetown player. Thompson asked him whether he would mind sitting to make room for Adams in the starting lineup. Smith replied in an instant.

“I was honored,” Smith said. “Ty has invested as much as anybody else has in our program with helping us and caring, being there even if he can’t physically participate.

“Tyler’s just another coach, really. In the games, when the coaches huddle up, he’s the first guy to speak up. He’s one of our teammates and our friends. At the end of the day, he’s just one of the coaches.”

On Saturday, Adams will again be a player. He will end his career in a Georgetown uniform, “Adams” across his shoulder and No. 10 on his back. He knows he will be both nervous and excited. He has been trying not to think about it too much, to keep the nerves at bay. But his teammates keep giving him advice. For once, they are coaching him.

“They’re just like, ‘Shoot a three,’ ” Adams said.