A revolutionary treatment for severe heart failure using embryonic stem cells seems to have worked, with the female patient resuming normal activity.

A woman treated with a revolutionary embryonic stem-cell therapy for severe heart failure is doing well three months after the operation, her cardiologist reports.

The patient, 68 at the time of the procedure last October, was given juvenile heart cells that had been grown in the lab from human precursor cells, Philippe Menasche of the Georges-Pompidou European Hospital in Paris said.

An ailing septuagenarian man was the first in the world to receive the treatment a few months earlier, but died of unrelated causes.

The young cells were transferred in a gel-laced patch applied to a damaged part of the woman's heart during bypass surgery last October.

"Today, she is much better. She is well, she is at home, and has resumed normal activity," Menasche said on Friday.

The damaged area of the heart is now functioning, he added, though it was unclear whether this was due to the patch or the bypass.

Menasche and his team said they were the first to use human embryonic stem cells to treat heart failure.

Extremely versatile, these cells can differentiate into any tissue of the body, one day possibly replacing damaged or lost organs. They have been shown to restore some vision in people with deteriorating eyesight.

There are ethical complications, though, as well as concerns that the transplanted cells may be attacked by the patient's immune system.

The new technique had not triggered any tumours in animal trials, said Menasche, and the female patient has not shown any negative reaction to the cells or immunosuppressant drugs.

The results were presented in Paris on Friday at the annual meeting of the French Society of Cardiology.

France's transplant watchdog has approved a six-patient trial to test the procedure's safety.