"He is continuing his rest and recuperation at an undisclosed location," said Ho's publicist Donna Jung. "We're delighted to say that his health is improving dramatically."

Ho, known for his signature tune "Tiny Bubbles," underwent a new treatment Dec. 6 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.

Ho was among the first patients selected for the VesCell adult stem cell therapy.

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.

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

In August, he 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.