Dodgers hang on to beat Rockies but get some bad news

DENVER — Kenley Jansen might be finished for the season and, by extension, so might be the Dodgers.

Jansen was unavailable to close out the Dodgers’ 10-8 victory over the last-place Colorado Rockies on Wednesday because of issues related to a heart problem that sidelined him for nearly a month last year, Manager Don Mattingly said.

So, although the high-priced offense came into form and Matt Kemp said he could be back in the lineup as early as Thursday, the Dodgers suffered a major blow to an already unstable part of their team that Mattingly has called the most crucial to their success: pitching.

Presumably, news about Jansen has heightened the urgency for the Dodgers to acquire a pitcher in a waiver trade by Friday, which is the deadline to add playoff-eligible players.

The Dodgers are still deciding what to do with Jansen, who declined to speak to reporters or allow the medical staff to explain his condition. But the decision at hand appears to be whether to put him on blood-thinning medication.

When Jansen was hospitalized because of an irregular heartbeat last year, he was put on the medication, which is designed to prevent a clot or stroke. One of the medication’s side effects is that it can cause a person to bleed profusely, even to the point of death, if struck by, say, a batted ball. So while Jansen took the medication last year, he wasn’t even allowed to be on the field during batting practice or in the dugout during games.

Jansen can be dominant at times — he has a 2.54 earned-run average and has converted 25 of 31 save opportunities — but isn’t exactly a juiced-up Eric Gagne. Ronald Belisario, who closed Wednesday’s game, doesn’t figure to be much of a downgrade.

But there’s a problem, one significant enough that it could derail the Dodgers’ season.

With Chad Billingsley on the disabled list, Clayton Kershaw is the only starting pitcher who can be counted on to pitch seven innings with regularity. The other members of the rotation — Chris Capuano, Aaron Harang, Josh Beckett and Joe Blanton — are five- or six-inning pitchers.

This, coupled with the reality that the Dodgers don’t have many dependable arms in the bullpen, has made the task of getting the ball to the closer a difficult one. The middle relief corps already took a hit when left-hander Scott Elbert was put on the disabled list Wednesday. If Belisario is taken out of a middle-relief role because he has to close, that challenge will only become greater.

Brandon League, who hasn’t given up a run in his last four appearances, could be the setup man. He was an All-Star closer with the Seattle Mariners last year but lost his way and his job this season before he was traded to the Dodgers.

Mattingly pointed to how the Dodgers can add arms when rosters expand Saturday, but whom will they be adding? Rehabilitating Matt Guerrier hasn’t pitched in a major league game since mid-April. Former closer Javy Guerra was wildly inconsistent before his demotion to the minors this month.

Of course, none of this will matter if starters can do what Blanton did Wednesday. Blanton held the Rockies to three runs and 10 hits over 71/3 innings to earn his first win as a Dodger.

The bullpen’s shortcomings could also be masked by the high-priced, new-and-improved offense, which had a six-run third-inning highlighted by a two-run single by Adrian Gonzalez and a solo home run by Hanley Ramirez.

A.J. Ellis added some insurance runs with an eighth-inning grand slam to increase the Dodgers’ lead to 10-1.

But Blanton, Shawn Tolleson, Randy Choate and Belisario combined to give up seven runs in the bottom of the inning, when Colorado closed the gap to 10-8. Belisario earned a five-out save.

Mattingly claimed to be pleased with his team’s performance,but conceded, “It was a lot closer than I wanted. I used a lot more people than I wanted.”

He could be saying that a lot more in the coming days and weeks.

dylan.hernandez@latimes.com