A fight with Marcus Foligno immediately ensued after the hit. Bartkowski was given a five-minute major for interference and a game misconduct.
Bartkowski came flying in as the Sabres were trying to break out of their zone, and it appeared he extended his elbow to the head of Gionta, sending him spinning through the air and leaving him with a cut on his face. The Sabres forward was eventually able to get up on his own power.
Gionta and Foligno were forced to leave the game due to injuries, and the Sabres soon said each would not return to the contest. (After the game, Sabres coach Ted Nolan said Foligno would be out for "a while" due to a "freak" upper body injury.)
The Boston Globe's Amalie Benjamin reported later Sunday night that Bartkowski won't face additional discipline from the NHL for the hit.
Bartkowski had played in 15 games for the Bruins this year entering Sunday and had amassed just four penalty minutes before Sunday night's incident.
The Bruins went on to win 4-3 in overtime.