It was Schwartz's sixth power-play goal this season, and being in position to capitalize on Pietrangelo's shot has been a big part of that success.
"I guess I'll just keep shooting, he'll just keep getting in the way," a smiling Pietrangelo said. "Whatever. It works."
Vince Dunn scored his sixth goal at 11:22 to extend the lead to 3-0. Dunn also had an assist for his first multipoint game of the season.
Schenn scored on the power play at 12:21 to make it 4-0. It was his 17th goal, giving him as many goals in 38 games this season as he had in 72 games last season.
It was also his fifth point in the past three games (three goals, two assists).
The Blues needed a combined 33 seconds to score on their two power-play chances, which Pietrangelo said is the result of a more aggressive approach.
"Yeah, we've talked about trying to shoot a little bit more off draws and at the start of the power play," said Pietrangelo, who had two assists. "I wish it was that easy every time."