The thumping began in his chest, pounding into his throat, grabbing at his breath.

Kenley Jansen was scared. His heart was literally broken. He wanted to walk off the mound and shut down his season and fix it.

But he couldn’t. He wouldn’t. There was pennant race to survive. There was a World Series to win.

He worried about his health, but he cared about his team. He didn’t want to risk a stroke, but he didn’t want to miss October.

He suffered an irregular heartbeat episode on Aug. 9 in Colorado, he was told he could need ablation surgery, but 11 days later he came back anyway. He kept pitching. He swallowed his medicine and smothered his fears and kept pitching.

“I was two personalities,” he admitted one recent evening at Camelback Ranch. “One personality wanted to be there for my guys. The other personality wanted to call it a season and go do the surgery and get off the medication.”

He kept pitching, but the dueling attitudes fought for space in his head, bled distraction into his right arm, and, in the end, everyone lost.

After returning from the disabled list Aug. 20, armed with only that blood-thinning medication and a November surgery date, Jansen gave up four home runs in his first three games, and seven total runs in his first four games.

While his numbers calmed down for the rest of the regular season, he was never again a sure bet. Everyone held their breath with every pitch. He missed a late-season trip to Colorado because of fears that the altitude would trigger another heart episode. He didn’t miss many bats with his trademark cutter, and wound up giving up the most homers of any National League reliever with 13.

In the end, the worst baseball fears were realized at the worst of times. In his first two World Series appearances against the Boston Red Sox, Jansen gave up two home runs and blew two saves and the Dodgers blew a second consecutive shot at their first World Series championship in three decades.