"If the doctors tell you, "No, don't play,' What can you do?" Jansen said. "It's tough for me to play there. If I go out there feeling like that, I might have an episode. I don't think Donnie was frustrated with me. It was a tough loss."
Without Jansen, Mattingly's bullpen blew a two-run lead in the bottom of the ninth inning and lost to the Rockies at Coors Field, 7-6.
After the game, Mattingly wouldn't discuss why Jansen was unavailable. On Thursday, he said he was respecting the player's wishes for confidentiality. Jansen confirmed he didn't want his condition discussed until tests could be done, which he said was part of the reason that he refused to speak with reporters after the loss.
"It was a tough night and I was feeling guilty seeing how the game went down, and it just wasn't time to talk about it," he said. "I was being kind of private."
Jansen attributed that to his 2012 ablasion surgery to correct an irregular heartbeat, having suffered an episode that year in Denver. Jansen often has said he feels sluggish in Denver. He said the club will take preventative measures, including daily IVs, to avoid more problems when the Dodgers return to Colorado in September.
Although the 2012 surgery was deemed a success and Jansen is not known to have had additional irregular heartbeat episodes like the one in Denver that year, he said he lives with the underlying condition and high elevation can trigger high blood pressure and the serious health issues that come with it.
"Because of my history there [in Denver], I was beginning to think, here we go again," he said. "Then in the ninth inning, I felt I let all my teammates down. That's why I didn't want to talk about it."
Mattingly said he wasn't mad at Jansen, but he did sound annoyed with reporters.
"I was angry from the standpoint that we just lost a tough game," Mattingly said. "There was nothing to be mad at Kenley about. I am taken aback by you [media] guys thinking you're entitled to every bit of information, whether it's related to family or different things. There's situations if you can't give up that information, you can't do it. It's his situation that we're talking about. So you're always going to respect that situation first."