DETROIT -- Lions rookie quarterback Joey Harrington will miss the rest of the season because of an irregular heartbeat.

Harrington, the No. 3 overall draft pick out of Oregon, left Sunday's game against Tampa Bay with the heart problem and was taken to the hospital for tests and observation.

He was expected to stay in the hospital until Monday evening.

Doctors said Harrington's heartbeat returned to a normal rhythm before he was hospitalized. Lions coach Marty Mornhinweg said the ailment is not career-threatening. Detroit (3-11) has two games remaining this season.

"If this were Week 5, we would expect him to return, but there is no way that he will be back within two weeks,'' Mornhinweg said.

Harrington apparently has supra ventricular tachycardia (SVT), which affects the top of the heart, the Detroit News reported. It is not as serious as ventrical tachycardia, which involves structural damage to the heart and can be fatal.

Surgery or medication is the likely treatment for Harrington.

Medical officials familiar with arrhythmia told the Detroit News that a surgical process called a catheter ablation is the most likely course of treatment for Harrington because of his age and his occupation.

"The success rate is probably well in excess of 90 or 95 percent," Dr. Stephen Smith, director of inpatient cardiology at Henry Ford Hospital, told the newspaper. "And it's usually very safe. I cannot recall somebody who died during an ablation.

"Sometimes, there's a little swelling in the heart tissue. There's a small recurrence rate."

Lions trainer Al Bellamy said while no final diagnosis has been made, about 20 percent of the population suffers from similar conditions.

Harrington's family has a history of minor heart problems. His father, John, has lived with arrhythmia for years, as has an uncle. Arrhythmia is a medical term for an irregular heartbeat.

Harrington entered Sunday's game having completed just over 50 percent of his passes, with 2,294 yards, 12 touchdowns and 16 interceptions.

"I am 100 percent sure that he is going to be 100 percent fine,'' Mornhinweg said. "We are planning for Joey to be taking part in our off-season program within a few weeks. This is something that his father and uncle both have, and something that I've coached players with.''

"Joey is doing fine, and we expect that he will be released soon,'' Bellamy said. "We are just going to run every possible test and evaluation and take every possible precaution. We've had players experience this before, just not during a game.''

Harrington's spirits were high enough to joke about his condition, relayed by his coach.

"He said to tell you that Warren Sapp and Simeon Rice scared him, and that's when his heart started racing,'' Mornhinweg said.

Harrington called his parents in Portland, Ore., from Ford Field, moments before he was taken in an ambulance to the hospital. Valerie Harrington said she thought the phone ringing Sunday was odd, since no one usually calls during her son's games.

"On the fifth ring I decided to pick it up,'' she told the Detroit Free Press. "And it was Joey.''

Harrington told his mother: "I'm just calling to let you know that I'm OK. They're being really cautious, but I don't want to leave'' the game.

Valerie Harrington said she and her husband, John, were glad the Lions' medical team took the precautions that it did.

"We were grateful they put their foot down,'' she said. "He really wanted to go back in.''

Information from The Associated Press was used in this report.