快猫短视频

HEART pacemakers can become infected, which means that some patients must
undergo potentially fatal surgery to have them removed. Now a new coating for
pacemaker wires should allow them to be removed more easily, say its inventors,
making the operations far safer.

Pacemakers are implanted just below the collarbone, but the wires from them
that monitor heartbeat must be passed through the veins to the heart. 鈥淭he main
problem is if you get an infection the wires are a direct route to the heart,
and that鈥檚 not good news,鈥� says Lee Lewis of the National Heart and Lung
Institute at the Hammersmith Hospital in London.

One way to prevent infections reaching the heart is to remove and replace the
infected pacemaker wires. But stripping the wires out of the veins is not
simple. When the wires are implanted, the body recognises them as foreign and
launches an attack. As part of this, oxygen radicals are released which trigger
the formation of a thick layer of the sticky blood cells called platelets. This
process鈥攌nown as fibrotic encapsulation鈥攅ffectively seals the wires
from the rest of the body.

鈥淥nce the wires have this encapsulation, removing them is quite a nasty
procedure, because they鈥檙e basically anchored to the insides of the veins,鈥� says
Lewis.

Now Kishore Udipi and his colleagues at MetaPhore Pharmaceuticals in St
Louis, Missouri, have found a way to prevent pacemaker wires from sticking to
vein walls. The key is a new drug called superoxide dismutase mimic, which
speeds up a natural reaction in the body for soaking up oxygen radicals. Coating
the wires with the drug should prevent the build-up of the clinging platelet
coating.

To test the idea, Udipi made discs of polyurethane鈥攖he polymer used to
coat pacemaker wires鈥攁nd covered them with the drug. He then implanted the
discs into rats. When, after a month, the discs were removed, he found that
those coated with the drug showed far fewer signs of fibrotic encapsulation than
uncoated polymer discs. 鈥淭he coating reduced the inflammatory response, and the
fibrotic capsule build-up was much less,鈥� says Udipi.

Lewis says the coating could be a huge help. 鈥淚f it could stop the adherence
of the wires,鈥� he says, 鈥渋t would make a hell of a lot of difference for the
辫补迟颈别苍迟蝉.鈥�