Nationals reliever Will Harris will undergo surgery Friday for thoracic outlet syndrome, a condition where blood vessels or nerves in the space between an individual's collarbone and first rib are compressed. Harris could miss the remainder of the season, according to manager Dave Martinez.

During Spring Training, Harris was diagnosed with a blood clot in his right arm after undergoing an MRI. The 36-year-old then met with a specialist in St. Louis for a second opinion, who ruled out the possibility of a blood clot or thoracic outlet syndrome.

When speaking with reporters the day of his return from the IL on May 4, Harris worried what a thoracic outlet syndrome diagnosis would have meant for his career.

“I’m not in the beginning of my career, let’s say,” Harris said. “So, getting a thoracic outlet syndrome diagnosis there was not good. I thought maybe, ‘Wow, 2021 may be over.’ Who knows how I’m going to come out of that. Moving past that had definitely been a blessing.”

The reliever made his 2021 season debut that day, striking out two in a scoreless inning. Over seven more appearances, Harris noticed swelling, discoloration and pressure in his right hand after each outing. In his final appearance, May 22 against the Orioles, the right-hander was unable to record an out, allowing two runs on three hits against three batters.

“It was frustrating because he wants to help us win, and he was going out there doing the best he can,” Martinez said. “His hand would swell up on him, and that was no fun for him after every game.”

Harris was placed back on the IL on May 23 and met with a specialist in Dallas, this time confirming the thoracic outlet syndrome diagnosis. After speaking with his family, he elected surgery.

“After talking to [Harris] yesterday, he actually is in pretty good spirits,” said Martinez. “They finally know something, and they think that this is really going to help him. So, with that being said, he just wants to have the procedure done and get ready as quick as he possibly can so he can come back and hopefully have no other issues.”