MESA, Ariz. — Chicago Cubs second baseman Mark DeRosa will undergo a heart procedure in Chicago tomorrow to correct an irregular heartbeat.

Team doctor Stephen Adams said DeRosa is expected to return to Arizona on Sunday, be back on the field as early as Monday and ready to play in spring training games by March 8.

"Theoretically, this should take care of the problem," Adams said today.

Alan Kadish, a cardiovascular electro physiologist at Northwestern Hospital, will perform the hour-long procedure that Adams described as "simple but very high tech."

DeRosa should return to his Chicago home Thursday night, Adams said.

The infielder experienced an irregular heartbeat Saturday during a workout and spent the night in a Mesa hospital. He returned to Chicago on Monday and underwent a medical evaluation Tuesday.

"We're thinking about Mark," said Cubs manager Lou Piniella, whose team went through a morning workout Wednesday before its spring training opener Thursday against the San Francisco Giants in Scottsdale. "Everything will go fine and he'll be back this weekend."

DeRosa, who turned 33 on Tuesday, said earlier this week he'd had the condition since he was a teenager.

"He's in an excellent mood. Ready to go, very open," Adams said.

Cubs shortstop Ryan Theriot, DeRosa's locker-mate in spring training and double-play partner, said he talked to his friend Tuesday.

"He seems fine. He's real anxious to come back, get out here and play some ball," Theriot said.

Theriot said DeRosa was upbeat, "but nobody enjoys going to the doctor, especially when it has to do with heart."

In Thursday's procedure, DeRosa will undergo an electrophysiology study in which Kadish will attempt to induce atrial arrhythmia.

Depending on what is found, Adams said DeRosa might then undergo a radio frequency catheter ablation, a medical treatment that uses electrical energy to destroy tissues in the heart that are causing rhythmic disturbances.

"They'll try to map out the pathway (his heart) jumps into," Adams said. "Hopefully, that will be curative of his past problems with jumping into atrial arrhythmia."