Patients undergo dialysis around three times a week

Most have a synthetic tube inserted under the skin, where they are "hooked up" to a machine every few days.

But this places huge pressure on patients' veins, which can close up, leading to them needing surgery to correct the problem.

Experts at Imperial College are developing a spiral shaped graft which they say will not have these problems.

This is a great idea. If the clinical trials are successful, it will be a superb advantage for patients Nick Turkentine, National Kidney Research Fund

There are around 19,000 people receiving kidney dialysis in the UK.

Campaigners think around a third could directly benefit from the device, mainly those who have been on dialysis for a long time, and those who have developed renal failure because they have Type 2 diabetes.

Patients undergo dialysis because their kidneys have failed, and cannot purify the blood as they should.

The dialysis performs this role, taking the blood out of the body and returning it cleansed.

But problems can occur at the point where the dialysis machine is connected.

Prior to the treatment, surgeons implant the tube, known as a vascular access graft under the skin, connected to a major vein.

But sometimes blood flow through the tube is restricted.

The grafts typically develop a potentially lethal disease, called 'intimal hyperplasia', which can block the downstream junction with the natural vessel in just a few months.

This results in most grafts requiring replacement within a year, and many patients require remedial surgery up to three times a year.

The researchers at Imperial say it can be more effective because is has a different, spiral shape.

This allows blood to "swirl" through the graft, mimicking its natural action, and reducing the likelihood of problems developing.

The graft has been tested in the laboratory, and the Imperial team are now beginning trials of the "Swirlgraft" in patients in conjunction with experts in other parts of Europe.

The scientists have formed a company called Veryan to continue their work on the device,

The company has been given �95,000 by Nesta, the National Endowment for Science, Technology and the Arts, as well as funding from Imperial College and Nikko Principal Investments Ltd.

'Benefits'

Professor Colin Caro told BBC News Online: "These patients have to deal with kidney failure, and all that that entails.

"Then they have to undergo dialysis, and have a graft fitted which, on average, lasts around a year - and it has to be tinkered with every three months."

Professor Caro has been carrying out research into blood flow for almost 40 years. He said he hoped the graft would make a real difference to dialysis patients.

"If it delays the need for surgery, then everyone gains - the patient, and the health delivery service."

Nick Turkentine, of the National Kidney Research Fund, said: "This is a great idea. If the clinical trials are successful, it will be a superb advantage for patients."

AMark White, Nesta's director of invention and innovation, said: "We are delighted to be investing in a product which meets an urgent need for improved clinical performance, as well as bringing huge benefits to dialysis patients from around the world."