No theories about Panther's irregular heartbeat

Defensive end Mike Rucker, forced to leave the Carolina Panthers game after just one series Sunday because of an irregular heartbeat, is expected to participate in practices this week and to play in Sunday's home game against San Diego.

While acknowledging that doctors still haven't pinpointed the exact cause for a problem that left Rucker short of breath, Panthers coach John Fox said Monday that the Pro Bowl end is "fine" after undergoing a battery of tests.

"I've [seen it with players] on a few occasions," Fox said. "Sometimes it can be from the medications they take. Sometimes it can be heat-related or from altitude. There are a lot of different reasons."

Fox said he anticipates Rucker will play this week and, asked if there were any theories about the irregular heartbeat, he said: "None that I have heard."

Rucker, 29, revealed after Sunday's game in Philadelphia that he had experienced similar symptoms in an Oct. 10 game at Denver, but he and team doctors attributed it to the altitude there. He was able to bring the problem under control at Denver and to resume playing.

There were no pregame warnings Sunday afternoon that suggested the potential onset of another irregular heartbeat episode, Rucker said. The six-year veteran, who is likely to have more precautionary testing, said he has no history of heart problems.

Fox said that, in Sunday night tests conducted when the team returned to Charlotte, there were no "structural problems" or "internal problems."

Len Pasquarelli is a senior NFL writer for ESPN.com. To check out Len's chat archive, click hereInsider.