When someone has a heart attack, their heart is permanently left with a section of non-beating scar tissue. Even though the rest of the organ may still function, that one bit can disrupt its rhythm, potentially leading to disorders such as arrhythmia. Several groups are developing "heart patches" to help address the situation, with one of the latest coming from Australia's University of New South Wales (UNSW) and Britain's Imperial College London. Unlike some others, it can be attached to the heart without the use of stitches.
The base material of the flexible patch is chitosan, a polysaccharide derived from crustacean shells. On top of that is a layer of polyaniline, an electrically-conductive polymer. Added to it is phytic acid, a plant-derived chemical that keeps the polyaniline in its conductive state. This is an important addition, as most conductive polymers ordinarily lose their conductivity shortly after being exposed to body fluids.
The idea is that the patch be applied over top of scar tissue, forming a bridge that allows electrical signals to travel unimpeded from one side of it to the other. Using a patented technique, it can be attached to heart tissue simply by shining a green laser on it. Not only is this less invasive than using stitches, but it reportedly also allows the patch to move more easily with the rest of the heart.
Lab tests on rats have already proven promising, with patches improving the conduction of electrical impulses across scar tissue, while remaining stable and conductive for up to two weeks. That said, they may not be finding their way onto live human hearts anytime soon.
"We envisage heart attack patients eventually having patches attached as a bridge between the healthy and the scar tissue, to help prevent cardiac arrhythmia," says UNSW's Dr. Damia Mawad, who led the research along with Imperial's Prof. Molly Stevens. "However, our patch is at the very early stages of this research. This technology can now be used for basic research to gain insights into the interface between the material and tissue."
A paper on the project was recently published in the journal Science Advances.
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