Subban said, "I felt we had the start that we wanted in getting that first goal. I thought we could've had a couple in the first."
Nashville outshot Dallas 12-9 in the period.
"You have to expect they're going to come out hard, first [Stanley Cup] Playoff game of the year," Stars defenseman John Klingberg said. "They're the favorites and they were into it, and I think we settled in pretty good. We weren't happy with our first period, but we settled pretty good, and then we just took over the game. That's exactly how we wanted to play, and we did a good job."
Heiskanen scored on the power play to tie the game 1-1 at 12:37 of the second period. His wrist shot from the right point went off defenseman Mattias Ekholm's leg.
At 19 years, 266 days, Heiskanen is the youngest defenseman in Stars history to score a goal in the playoffs.
"You know, early, I guess I would say I'm not surprised anymore, but it's truly impressive," Bishop said. "He plays like he's been in the League for 10 years. Just goes about his business quietly and efficiently, and like I said before, this guy's going to be a star in this league for a long time."