Popular US talk show host David Letterman has undergone an emergency quintuple heart bypass after a test found one of his arteries was seriously constricted.

The 52-year-old had an angiogram because of what he said was high cholesterol and a history of heart disease in his family.

The test, in which a flexible tube is inserted into an artery and dye injected, found the constricted artery.

Dr O Wayne Isom, who performed the procedure at New York Presbyterian Hospital on Friday, said it went smoothly

He predicted a rapid recovery.

"Dave has the heart muscle of a 20-year-old," he said.

"He's fine," said Mr Letterman's spokesman Steven Rubenstein.

Mr Rubenstein said Mr Letterman's "Late Show" would transmit reruns until he recovers.

Mr Letterman has made a long-running joke of his health, starting years ago when he discovered he had high cholesterol.

For a month he went on an oat-bran diet, complaining nightly about its taste and consistency.