Mariners general manager Jack Zduriencik said in a statement, "We were relieved once we heard the details from John and Michelle and that John is safe at home and in good health. Contrary to earlier news reports, the reason John was hospitalized was because of an extremely high heart rate. We have let them know that the Mariners will do whatever we can to assist them."
Wetteland spent 12 years in the Major Leagues and was selected as the World Series Most Valuable Player in 1996 for the Yankees.
He retired as a player in 2000 while with the Rangers and established his residence in the Dallas area working at a baseball coach for Liberty Christian School in Argyle while also coaching for the Rangers and Nationals before joining the Mariners this past season.
He was credited with building one of the strongest bullpens in the Major Leagues, helping the Mariners post the lowest team ERA in the American League. He was one of five coaches retained from manager Don Wakamatsu's coaching staff.
"I just heard about it, and I really have no idea what really happened," said Mariners closer David Aardsma, who is vacationing in Carmel, Calif. "My thoughts are with his wife and their kids, and I hope nothing really wrong is going on."
Aardsma said he has kept in touch with Wetteland via phone calls since the regular season ended, most recently about two weeks ago.
"It was like talking to him on an off-day and I would see him at the ballpark the next day," he added. "He's very engaging and good-natured and to hear something like this is just shocking."
Aardsma said Wettleland was "the man behind the entire bullpen."
"He was so instrumental in what we did as a group out there. He's one of those been-there-done-that kind of guys, and I benefited as the closer just by being around him and talking to him. He sat me down, talked to me and learned how I click.
"Wett helped me physically with mechanics, but more than that, he taught me about the closer's role and the hitters."
Aardsma went from a reliever with no career saves coming into the 2009 season to someone who went 38-for-42 in save opportunities.
Right-handed reliever Mark Lowe, who appeared in a career-high 75 games this past season, also was stunned by the news out of Dallas.
"Obviously, it caught me off guard," Lowe told the Seattle Times. "He's a strong man. I know he's been through a lot. I know he'll pull out from it and be fine. He's going through a rough time, but I have complete confidence everything is going to be fine. Everyone goes through their times."