memories of my TV youth dies yesterday:

John Ritter, whose portrayal of the bumbling but lovable Jack Tripper helped make the madcap comedy series "Three's Company" a smash hit in the 1970s, has died of a heart problem, his publicist said Friday. He was 54.

Ritter fell ill Thursday on the set of his ABC sitcom "8 Simple Rules ... For Dating My Teenage Daughter," said Susan Wilcox, his assistant of 22 years.

The cause of death was a dissection of the aorta, the result of an unrecognized flaw in his heart, said his publicist, Lisa Kasteler.

Ritter died at Providence St. Joseph Medical Center shortly after 10 p.m. Thursday.

Ritter, a Southern California native who lived in Beverly Hills, came to prominence for his role in "Three's Company" and had appeared in more than 25 television movies and a number of films.

Ritter, who would have turned 55 on Wednesday, made a successful return to sitcom acting with "8 Simple Rules" last year, and the ABC show was scheduled to begin its second season on Sept. 23.

At the Burbank hospital where he died, Ritter was accompanied by producers and co-workers, his wife, Amy Yasbeck, and 23-year-old son Jason, Wilcox said. He is survived by three other children, Carly, Tyler and Stella.

"It's just stunning, unbelievable," said Wilcox. "Everybody loved John Ritter. Everybody loved working with him. ... Whatever set he was working on, he made it a very fun place."

ABC released a statement saying: "All of us at ABC, Touchstone Television and The Walt Disney Company are shocked and heartbroken at the terrible news of John's passing. Our thoughts and prayers are with his wife and children at this very difficult time."

Ritter was the youngest son of Western film star and country musician Tex Ritter. He graduated from Hollywood High School and earned a degree in drama from the University of Southern California.

Ritter appeared in more than 50 plays nationwide and won critical acclaim for his recent nine-month role in the Broadway premiere of Neil Simon's "The Dinner Party."

He received an Emmy and other awards for his "Three's Company" role and was honored by the Los Angeles Music Center in June with a lifetime achievement award.

so sad