ARLINGTON -- Mets pitcher Jon Niese left Saturday's game in the sixth inning with a rapid heartbeat, but neither he nor the team considered the issue serious.
"I just kind of overheated a little bit," Niese said. "I was breathing heavy. I stepped back. I just couldn't really catch my breath."
After striking out Adrian Beltre to open the sixth inning, Niese began having trouble breathing, spending several moments at the back of the mound in an attempt to catch his breath. Manager Terry Collins and trainer Ray Ramirez took notice, emerging from the dugout to check on Niese one batter later. Though neither man was overly concerned, Collins decided to remove Niese from the game for precautionary reasons after Nelson Cruz doubled with two outs in the inning.
A quick checkup from Rangers team doctors revealed nothing abnormal.
"I don't think it's going to be serious," Collins said, noting that Saturday's high-90s temperatures likely played a role. "I just wasn't going to take a chance on a day like today. It's too hot. Anything can happen. This kid's too young."
Niese, who classified his removal from Saturday's game as "more precautionary than anything" and "no big deal," said he had never before experienced cardiac issues outside of typical in-game heart-rate spikes. He plans to undergo a reexamination Tuesday in Detroit, but does not expect anything to come of it.
"It's just one of those things where the adrenaline goes and your heart starts racing and you take a deep breath and calm down," Niese said. "It's really not an issue."
Anthony DiComo is a reporter for MLB.com. Follow him on Twitter @AnthonyDicomo. This story was not subject to the approval of Major League Baseball or its clubs.