Ho, 75, known for his signature tune "Tiny Bubbles," underwent a new medical procedure not approved in the United States that involved taking stem cells from his own blood to multiply them and later to inject them into his heart, in hopes of regeneration.

"He came through the procedure with flying colors," agent Ed Brown, a close Ho friend, said in a telephone interview from his home in Malibu, Calif. "His vitals are excellent. Everything seems to be where it's supposed to be and everyone is quite happy.

"However, it's premature — because he is in ICU — to give you any statement of certainty."

Ho, who has appeared with Hollywood's biggest stars and entertained tourists for more than four decades, has been suffering from heart problems for about a year and had a pacemaker installed a few months ago.

In August, Ho was admitted to a local hospital with shortness of breath. He was treated for an abnormal heart rhythm and released after three days. He soon returned to his Waikiki show on a reduced schedule, but the show at the Waikiki Beachcomber Hotel has been dark since he left for Asia on Nov. 26.

"He felt well enough, but his pacer sometimes would go off in his chest and scare the hell out of him," Brown said. "That's a difficult thing to live with right in the middle of 'Tiny Bubbles."'

Publicist and spokeswoman Donna Jung said Ho hopes to return to the stage soon. He is expected to return to Honolulu from Bangkok in about two weeks.

Ho is known as a workaholic, devoted to his fans, since he first performed in Waikiki in the early 1960s. He has refused to join many of his aging fans in retirement.

Stars such as Lucille Ball, Sammy Davis Jr. and Frank Sinatra have attended Ho's shows. He also hosted the "The Don Ho Show" on ABC from 1976-77.

"That's all he understands. Work is a form of retirement for him," Brown said. "That's the way he takes his vacation — on the stage."

"If he's going to live, he's going to be on that stage."

There were no other medical options for Ho and he did it as a "last resort," Brown said.

He called the singer's heart condition, "extremely serious."

"It wouldn't hurt if the millions of his fans would start to pray for him," Brown said. "Don, as do I ... believe in the power of prayer."

The "VesCell" technology Ho underwent was developed by TheraVitae Co., which has offices in Thailand and laboratories in Israel, where Ho's stem cells were sent to be multiplied.

Brown noted that Ho was not participating in controversial procedures involving embryonic stem cells.

"Don did not take stem cells from a fetus. He doesn't believe in that," he said. "He took blood from his own body and re-injected that into his heart."