The Los Angeles Dodgers are expected to be without All-Star closer Kenley Jansen for a key weekend series with the Colorado Rockies after a team cardiologist recommended the right-hander not travel to Denver. Twice in his career Jansen has experienced an atrial fibrillation episode, more commonly known as an irregular heartbeat, while the Dodgers were in the high altitude of Colorado. The most recent episode happened Aug. 9 before the start of a four-game series at Coors Field, with Jansen calling 911 when an accelerated heartbeat would not subside.