Kenley Jansen knew what was happening when his heart started racing, his chest became tight and breathing became difficult while he was on the mound in Colorado earlier this season.

The same thing happened in 2011 and 2012. His heart was in atrial fibrillation.

"I wasn't scared. I knew exactly what it was," Jansen says now. "I was pissed.

"I thought my season was over. I'm like, man, f--- this. Not again. We're trying to go back to the World Series. I have a chance to win another Trevor Hoffman award. Man!"

Jansen is back with the Los Angeles Dodgers after being away from the team due to the irregular heartbeat on Aug. 9. He didn't travel with the team to Denver to face the Rockies this past weekend.

"I tried everything to get it back into rhythm for 15, 20 minutes. And then I'm finally like, all right, let's just call 911," Jansen said.

"I remember being annoyed in the ambulance too. It was driving so slow. I just wanted to get to the ER so they could fix it."