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EDITIONS
Thursday, 7 October, 1999, 00:17 GMT 01:17 UK
Genetically-modified veins could save lives
Half of all bypass patients suffer further problems
A hi-tech procedure, dubbed the 'Schwarzenegger effect' by its creator, could help extend the life of blood vessels used in heart bypass operations.

Veins from elsewhere in the body are commonly used to replace clogged up or hardened arteries supplying blood to the heart.

However, arteries are naturally stronger than veins, and the bypass operation often fails because the vein reacts badly to the increased blood pressure.

Very often, the vein will a grow a thick layer of muscle to protect itself - and this can make it more likely to clog than the blood vessel it replaces.

A patient undergoing major surgery could require more surgery - at higher risk - within five to 10 years.

Dr Victor Dzau, of Brigham and Women's Hospital in Boston, says he has found a way of making the veins develop the right sort of muscle, which should help them become stronger and last longer.

The vein, removed ready for implantation, is injected with DNA which alters the genetic makeup of the muscle cells, and stops them from dividing as quickly.

"It is what I call the Schwarzenegger effect," Dr Dzau said.

"The graft is harvested from the patient while the surgeon is cracking open the chest and getting the patient on bypass."

Tested on legs

At the moment, his technique has not been tried on heart bypass patients, but has been tested on a condition called claudation, in which an artery in the leg becomes similarly clogged and needs replacement.

The arteries supplying the muscles of the heart become clogged
With the exception of a few patients who suffered immediate blood clots, the bypasses have held beyond the six month mark.

Dr Keith Channon, clinical reader in cardiovascular medicine at the University of Oxford, and a consultant cardiologist from the John Radcliffe Hospital in the city, is also developing gene therapy on veins taken for bypass.

He said: "It has great potential as this is an extremely large problem in modern medicine. It could save lives and improve outcomes from surgery.

"About 50% of venous bypass grafts used for coronary artery surgery will be blocked by the 10 year mark."

He cautioned that other experiments hailed as breakthroughs in gene therapy, such as potential treatments for cystic fibrosis, had not yet translated into effective treatments.

Viruses used to change veins

Dr Channon's own work uses viruses - modified to make them safe - which "infect" the cells making up the veins with new genetic material.

Other surgeons are overcoming the problem of clogging vein grafts by using arteries which do not have a vital role in the body.

However, there is usually only enough material for one graft, and most patients need a triple, or even a quadruple heart bypass, in which three or four arteries have to be tackled.

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