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Artificial Organs and their Functions - ISU

Artificial Veins & Arteries
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Improving technology for patients

spiralvein.jpg
The corkscrew shape makes the blood flow in a spiral motion

New developments in technology are helping to create the better care and treatment of patients across the world.

One such development is the improvement of synthetic or artificial veins used in bypass surgeries. As of now, when one or more of a patients veins becomes clogged or damaged to the point where it is endangering the patient, a bypass must be performed. This involves either removing another vein from a patients body (usually within the thigh) and grafting it to either end of the damaged vein so that blood flow bypasses the damaged area, hence the name bypass. The other method involves the same procedure as before, only instead of obtaining the required vein from the patients body, the doctors use a synthetic version instead.

The synthetic vein would be the better choice, as it is less painful and uncomfortable for the patient. The only problem is, current synthetic veins wear out after about 2 years and have to be replaced. That's where the new technology steps in.

Dr. Peter Stonebridge discovered that opposed to the beliefs of the medical community, blood does not flow through veins in a straight path. Rather, the veins contract and relax as the blood passes through, which causes the blood to flow in a spiral motion through the veins.

With help from some colleagues, Dr. Stonebridge created a new synthetic vein that has a corkscrew interior to cause the blood to flow in the natural spiral fashion. The new design decreases the amount of wear and damage on the artificial vein, and the corkscrew shape also helps to prevent new blockages from occurring. The old design had a smooth interior, which is what cause them to only last for the 2 year period.

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.

How it works

-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

-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

-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

artery.jpg
An example of the older synthetic vein, with a smooth interior

By Jason Ferguson, Presented to Mr. Lech