British physician Peter Stonebridge first discovered that blood doesn’t flow in a linear pattern, but rather in a corkscrew fashion, back in 1991. Now, with help from some colleagues and an NHS grant, he has begun clinical trials of an “rifled” artificial vein with some impressive results.
Results from human trials into the new plastic vein — which is being developed for use in bypass operations — have shown a 100 per cent success rate in the first six months.
The artificial artery is different from those currently in use because it is “rifled” inside, like a gun barrel, and encourages blood to spiral as it moves along.
Until recently it was assumed that blood flowed in a straight line, and artificial veins were manufactured with smooth insides to reflect that. However, in 1991, Peter Stonebridge, of the University of Dundee, discovered that blood corkscrews as it flows, causing less friction or damage to arteries and helping to clear away potential blockages. He published his findings in The Lancet scientific journal. Since then, with the help of two other doctors and £6 million of public and private investment, he has developed an artificial vein to mimic the natural spiralling movement of human blood.
According to Professor Stonebridge, the simple adjustment from a smooth to a “rifled” vein has produced “remarkable” results in human trials led by researchers at Ghent University Hospital, Belgium.
The findings represent a breakthrough in the future treatment offered to the 10.7 million people in Western Europe who suffer from peripheral arterial diseases, including those that lead to amputations, heart attacks and strokes.
Professor Stonebridge set up Tayside Flow Technologies with John Dick and Graeme Houston, from Ninewells Hospital in Dundee, to develop the product. He said yesterday: “One would have expected some of the bypass grafts [artificial veins] in the trials to have failed, but none have. They are all still going which is remarkable.”
Currently, seven out of ten “smooth” artificial arteries used in below-the-knee bypass operations fail in less than two years and about 40 per cent of patients need a limb amputated. On that basis, approximately 20 per cent of the new “spiral” veins implanted into the legs of 22 trial patients should have stopped working after six months.
But so far all the grafts have stayed open and bloodflow speed has remained constant, researchers say. Professor Stonebridge said: “We have spent millions on proving the technology and developing techniques that are totally new. This is a big step forward.”
How it works
The new artificial vein mimics naturally occurring spiral laminar flow (SLF) of blood in healthy human arteries
The spiralling motion is started by the pumping action of the heart and continues in human veins, which expand and contract and also twist slightly to ‘spin’ blood as it flows around the body
SLF evolved in humans as the most efficient way of transporting blood, because it reduces turbulence and friction in arteries, causing less damage. It also naturally sweeps
In diseased veins, caused for example by smoking, obesity and diabetes, the spiralling motion breaks down and veins become sluggish. Blockages then occur that cause areas of turbulence in the vein and result in pain
The new artificial vein, used in bypass operations to replace diseased sections of vein, is a plastic tube with an internal groove that encourages blood to spiral again
Because the new vein makes blood spiral, the implant suffers less friction and less damage. As a result the implants are expected to have a lifespan of at least twice as long as smooth artificial veins currently in use