It is encouraging that there have been no complications after one year

Professor Ralph Damiano, Washington University School of Medicine

When the surgeon moves the handles, a computer converts this into precise movements 18 inches away down the instrument, by filtering out hand shake and making adjustments for the pivoting of the endoscopic probe through the ribcage.

A probe with a camera on the tip is controlled using voice commands.

In all, surgeons at Washington University School of Medicine performed heart bypass surgery on 19 patients using the machine.

A year after their operations, all of the patients were alive, and none had experienced any problems since.

Writing in the journal Annals of Surgery, the study's author, Professor Ralph Damiano, said: "Our results show that the most difficult part of the procedure can be performed endoscopically with robotic assistance.

Beating heart surgery

"It clearly enhanced our dexterity and performance - it is encouraging that there have been no complications after one year, though this still represents short-term results."

He is now hoping to use the robot technique in beating heart surgery - most bypasses are currently carried out with the heart stopped, and the patient on a heart lung machine.

If this is successful, recovery time and risk to the patient could be reduced still further.

Mr Tony DeSouza is a consultant cardiac surgeon at the Royal Brompton Hospital in London.

He and his colleagues are even further advanced in the use of the machine - having operated on more than one "beating heart" case in the past few months.

He told BBC News Online: "We are hoping that in the next two or three years we will do much more of this routinely.

"I don't know how many other centres could do the operation: it's like learning another language, and you need 100 hours of training.

"What is encouraging about this paper is that the results from using the machine are so good, even after a year."