HONOLULU — Legendary Hawaiian crooner Don Ho was moved out of intensive care at a Thailand hospital Wednesday and was doing well after an experimental procedure on his ailing heart, his doctor said.

Ho, known for his signature tune “Tiny Bubbles,” could be singing again by Christmas, said Dr. Amit Patel, a U.S. heart surgeon who oversaw the procedure in Bangkok.

The 75-year-old performer underwent a new treatment Tuesday that has not been approved in the United States. It involves multiplying stem cells taken from his blood and injecting them into his heart in hopes of strengthening the organ.

Patel said the singer had “an extremely weak” heart that was pumping far less blood than a healthy organ before the surgery.

His “ejection fractions,” a measurement of how well the heart pumps blood, was at 10 percent to 15 percent. A good heart has a rate of at least 55 percent to 65 percent, Patel said.

Ho, who has entertained tourists for more than four decades, has suffered from heart problems for about a year and had a pacemaker implanted a few months ago.

In August, Ho was admitted to a 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.

The experimental procedure was developed by TheraVitae Co., which has offices in Thailand and laboratories in Israel, where Ho’s stem cells were sent to be multiplied. The surgery costs roughly $30,000. “His prognosis in terms of recovering from surgery, thus far, is good,” Patel said in a telephone interview from Pittsburgh. “In terms of singing, it would really be up to him. I would not be surprised he’d be able to sing by Christmas, if not before.”

Besides “Tiny Bubbles,” Ho’s other hits include “I’ll Remember You,” “With All My Love” and the “Hawaiian Wedding Song.”