Heimerdinger, who is continuing cancer treatment after being diagnosed in November, confirmed to The Associated Press that he had been fired, hours before the team officially announced it.
The Titans also announced that defensive assistant Rayna Stewart and offensive assistant Richie Wessmanhad won't return.
"I met with Mike, Rayna and Richie today and informed them that they would not be retained as a part of the new staff," Munchak said in a statement released by the Titans. "These are not easy decisions, but I have a responsibility to move things in the direction that I have laid out for this team. We will continue to evaluate the rest of the staff moving forward.
"As it relates to Mike, I have a great deal of respect for him as a person and admiration for the way he is fighting against cancer. He is an innovative offensive mind, and we have worked well through the years, but I believe we need to go in a different direction at offensive coordinator. This wasn't about his health -- he is feeling good -- it is a change of direction for us. This is not something that I take lightly, and I wish him and his family the best."
Munchak promised that changes were coming when he was introduced as the Titans' coach Monday. He said anything is possible when asked specifically about Heimerdinger.
"I believe they made the right choice," Fisher said. "Munch has been in the league for a long time as a player and a coach, and he is regarded as one of the top, if not the top offensive line coaches in the league.
"I have confidence in him and think he'll do a great job. Mike and I are good friends, and he has been with this organization longer than I was. Whatever I can do for Mike in the future, I'd be more than willing to help. But he's going to do a great job."
Fisher acknowledged that Munchak likely would need to make some changes.
"Mike knows what he needs to do moving forward, and understands what changes need to be made," Fisher said. "He has some challenges ahead as far as putting his staff together, but I know Mike is going to make the right decisions as far as potential staff changes."
The firing of Heimerdinger gives Munchak six openings to fill on his coaching staff. Fisher fired defensive coordinator Chuck Cecil last month, and the Titans' defensive line coach, running backs coach and wide receivers assistant all left for other jobs.
Former teammate Bruce Matthews, now an assistant in Houston, is expected to be Munchak's top target to fill his old job coaching Tennessee's offensive line. The Houston Chronicle reported Tuesday that the Titans have told the Texans they plan to interview Matthews, who has agreed to but not signed a two-year contract with Houston.
The news of Heimerdinger's firing brought almost instant reaction Tuesday.
This was Heimerdinger's second stint as offensive coordinator with Tennessee. He helped the late Steve McNair earn co-MVP honors in 2003 and was part of three playoff teams in his first five seasons before leaving for the same job with the New York Jets in 2005. Fisher brought back Heimerdinger in 2008 after two seasons with the Denver Broncos.
Heimerdinger kept coaching and didn't miss a game after being diagnosed with a rare cancer the day before Thanksgiving. Fisher extended his coordinator's contract before the season ended.
The Titans' offense struggled in 2010, ranking 27th in the NFL in total yards per game (302.1) and 25th in yards passing (194.2). Johnson couldn't help the rushing attack much with just 107.9 yards averaged per game (17th overall).
Worse, the Titans rank last in time of possession, holding the ball just 25 minutes, 54 seconds per game. Tennessee was limited by injuries at quarterback, including the season-ending thumb injury to Vince Young on Nov. 21.
Asked about his offensive philosophy Monday, Munchak said the Titans have to stay on the field no matter what they do on offense.
"We struggled last year to stay on the field as an offense," Munchak said. "I'm stating the obvious. But we need to find a way, whatever that offense is, whatever that system is, we have to make first downs and stay out there."
The Associated Press contributed to this report.