Dodgers closer Kenley Jansen will miss roughly the next month as he receives treatment for an irregular heartbeat, sources tell ESPN's Buster Olney. Ken Rosenthal of The Athletic adds that Jansen's condition is considered to be "very manageable."

Jansen was hospitalized prior to the Dodgers' win over the Rockies in Denver on Thursday night and then returned to Los Angeles for additional testing. Jansen dealt with irregular heartbeats earlier in his career, but as MLB.com's Anne Rogers points out prior to Thursday he had not suffered a recurrence since undergoing surgery in October of 2012. 

This season Jansen in his age-30 season has pitched to a 2.15 ERA/185 ERA+ and a 4.36 K/BB ratio in 54 1/3 innings. He's also racked up an NL-leading 32 saves in 35 opportunities. Jansen, a three-time All-Star, is in the second year of a five-year, $80 million contract with Los Angeles. 

The Dodgers are of course locked in a tight battle for the NL West title, and losing Jansen for a month or so is a significant blow. While Jansen is out, manager Dave Roberts figures to play matchups in order to protect late-inning leads.