Per the Boston Bruins media team, defenseman Charlie McAvoy had a procedure done to correct an abnormal heart rhythm, an issue that has apparently been lingering for a couple months.
From team doctor Dr. David Finn and the Bruins media team:
Following the Bruins game on November 26, 2017, Charlie told team physicians that he experienced heart palpitations during the game. Subsequently he underwent an evaluation, which diagnosed him with a supraventricular tachycardia (SVT). The type of SVT Charlie has is not considered to be dangerous to his health but can recur at any time and causes significant symptoms.