The Jarvik 2000 has a tiny turbine

The pump is a miniature turbine, placed inside the left ventricle of the heart. This is the chamber which gives the heart most of its pumping power when it contracts.

It was partly developed by heart surgeon Mr Stephen Westaby, who is one of those flyng out to take part in Monday's pioneering operation at the Texas Heart Institute in Houston.

At the moment the device is not "licensed" as safe to use in the UK, meaning the operation cannot yet be carried out here.

However, Mr Westaby is hoping to start fully evaluating the metal heart in UK patients soon.

Following the latest operation, the pump will be only left in the patient for approximately six months. At that point, it will be removed and the patient given a transplant.

Then the removed heart will be examined to see how it coped with the implant.

Few British patients have been given any sort of artificial heart in the past.

Five months survival

Five years ago, a less sophisticated version was given to a 64-year-old man, who survived for five months.

Stephen Westaby with an earlier pump

Several children have been given pumps temporarily while they await transplants. In some cases, the extra help given by the pump takes the strain off the heart muscle, allowing it to recover.

However, the Jarvik 2000 is not cheap - at the moment each one costs in the region of �40,000, although it should become less expensive.

The extra research needed to prove the device works will cost �1m, and much must be raised from charity.