The Ducks confirmed the deal Monday to part ways with Manson, an eight-year NHL veteran who has spent his entire career in Anaheim. He is due to be an unrestricted free agent this summer.
The 30-year-old Manson is a former sixth-round pick who played his way onto the Ducks' roster in late 2014. The son of NHL enforcer Dave Manson has been a stalwart on Anaheim's blue line ever since, racking up 26 goals, 87 assists and 431 penalty minutes in 453 games.
Manson will be a complementary piece with the NHL-leading Avalanche (42-13-5), who are building up their depth in anticipation of a long playoff run.
Manson has four goals and five assists in 45 games this season, well off his career-best scoring pace from the 2017-18 season. He returned to Anaheim's lineup last weekend after missing 13 games with an injured finger.
Helleson is a 20-year-old Boston College product who has four goals and 21 assists in 32 games for the Eagles this season. He also played for the U.S. national team at the Beijing Olympics last month, recording one assist.
Manson is the first of three veterans headed toward unrestricted free agency to be moved by new Ducks general manager Pat Verbeek. Defenceman Hampus Lindholm and forward Rickard Rakell also are candidates to depart in trades if Anaheim can't sign them to new long-term contracts, although Verbeek has said he hopes to retain them.
The sixth-place Ducks (27-25-10) have faded in the playoff race in the past few weeks, putting them in a tough position to end their three-year postseason drought.