Heinen, a native of Langley, British Columbia, is part of a core of young talent that revitalized the Boston Bruins in 2017-18.
The Bruins selected Heinen, a forward, in the fourth round (No. 116) of the 2014 NHL Draft after he had 62 points (29 goals, 33 assists) in 57 games with Surrey of the British Columbia Hockey League. Then came two seasons at the University of Denver, where he had 93 points (36 goals, 57 assists) in 81 games. He was the NCHC Rookie of the Year in 2014-15 and the conference Forward of the Year in 2015-16.