Beam of light to open up blocked arteries

SHininG a beam of light into blocked blood vessels in the legs could cut the risk of heart attacks and strokes. the revolutionary treatment has been developed for peripheral arterial disease (Pad), which is thought to affect at least two million people in britain.

this is where arteries, most often in the legs, become narrowed due to fatty deposits called plaques. these plaques harden, restricting blood flow and causing pain.

as deposits accumulate, they cause a ‘buckling’ in the blood vessel walls that restricts blood flow. this encourages the formation of blood clots, which can travel to the arteries in the heart or brain, causing a heart attack or stroke. reduced blood flow to the legs also increases the risk of amputation.

drugs such as aspirin can reduce the risk of clots, but around one case in 20 becomes so severe that surgery is needed. this may involve angioplasty, where a balloon is inserted into the artery and inflated to clear the blockage. a metal tube called a stent is then inserted to prop the blood vessel open.

Yet stents can cause restenosis, where surrounding tissue becomes inflamed in response to the presence of the foreign body, causing another blockage.

another option is bypass surgery, where harvesteda healthyfrom elsewhereblood vesselin the body blood is vesselsewn on to to allow the damagedblood to divertYet cutting around out the the blockage. healthy vein requires a second incision. the new treatment could be more effective and less invasive.

doctors first insert a guide wire into the leg through a 1cm incision. the wire is fed through the femoral artery in the thigh down to the blockage and a thin tube, called a catheter, is pushed over it.

the catheter carries a pea-sized balloon which is inflated in front of the blockage to temporarily shut off blood flow, so the treatment can be carried out quickly. a second, longer balloon filled with a drug called natural Vascunaphthalimide lar scaffolding (nVs) is then inflated until it is pressing against the deposits on the blood vessel wall. this is held in place for five minutes while the drug seeps through pores in the balloon and is absorbed into the plaques.

next, both balloons are deflated and withdrawn. then a thin fibre with a tiny torch on the end is inserted, which lights up the treatment area.

the light activates a compound in the drug called naphthalimide, that reacts to light by forming a kind of netting within minutes.

this links with collagen — the natural scaffolding in blood vessel walls — to create a new taut lining across the damaged area. as is less likely than a metal stent to be regarded by the body’s immune system as a foreign body, it does not trigger restenosis.

a small trial in the U.s. involving 15 patients with severe Pad will test the effectiveness of the technique and the results will be available by 2019.

a U.s. study reported in the Journal of biomedical Materials research last year found that the nVs drug, when tested on pigs’ arteries, kept them open and reduced the ‘buckling’ effect in blood vessels.

kevin Varty, president- elect of the Vascular society for Great britain and ireland, believes the new technique has ‘potential’. He said: ‘researchers seem to be saying it will blend in better than a metal stent and is less likely to be seen as a foreign substance by the immune system.’

MeanwHile, scientists are working on a patch that could repair the damage caused by a heart attack.

a team of researchers at the Cambridge stem Cell institute have developed a patch using stem cells from embryos; the cells are applied to a scaffold made of collagen (the protein found in connective tissue) and other biological molecules.

the team plan to graft the patch onto a rat’s heart to see if it connects with blood vessels and beats in synchronicity with the rest of the heart.