A web blanket for weak hearts
Researchers at the University of Leeds in the UK have developed a new device which could put the beat back into weak hearts and free patients from a lifetime of anti-rejection drugs. Current implanted heart assistive devices 'function by sucking blood from the ventricles and then expelling it into downstream vessels.' In other words, this means they are in direct contact with the blood stream and that they 'require life-long drug therapy to suppress the immune system and prevent blood clotting.' The new system developed at Leeds is less invasive. This is 'a specially-woven web made from biocompatible material which will not be rejected by the body' and will wrap around the heart. Right now, it's only at prototype stage, but read more...
You can see on the left an image of "the web material that will be used in the development of the heart assist device." (Credit: University of Leeds on this page)
This research project has been led by Dr Peter Walker, senior lecturer in cardiovascular engineering and a member of the Institute of Medical & Biological Engineering, and by Dr Martin Levesley, the director of the Institute of Engineering Systems and Design.
Here is how the device will work. "The webbing wraps around the heart and therefore does not come into contact with the blood stream. Inbuilt sensors recognise when the heart wants to beat and trigger a series of miniature motors which cause the web to contract -- increasing the internal pressure and assisting the heart to pump the blood around the body. 'It’s a really simple concept that works in the same way as when you squeeze a plastic bottle, forcing the liquid inside to rise,' says PhD student David Keeling who has built a special rig to test the device."
Even if this device is only at prototype stage, its potential uses are huge. "As well as offering support to people suffering from heart and valve problems, the device could also be a bridging aid to patients as they wait for transplants, providing them with a better quality of life."
For more information, you might want to read an article published in Medical Engineering & Physics, an Elsevier journal, under the title "Hardware-in-the-loop-simulation of the cardiovascular system, with assist device testing application" (Volume 29, Issue 3, April 2007, Pages 367-374). Because the URLs inside Elsevier's website tend to be quite long, here is a shorter link to the abstract of this paper.
Here is the beginning. "This paper presents a technique for evaluating the performance of biomedical devices by combining physical (mechanical) testing with a numerical, computerised model of a biological system. This technique is developed for evaluation of a cardiac assist device prior to in vivo trials. This device will wrap around a failing heart and provide physical beating assistance (dynamic cardiac compression). In vitro, the device to be tested is placed around a simulator comprising a mechanical simulation of the beating ventricles."
Peter Walker has been working on this project for several years now. Here is a link to a 2002 article of The Reporter, the University of Leeds newsletter, "Ultrasonic heart blanket." "'The blanket would wrap around the heart, just touching the tissue but, unlike other devices which help the heart to pump, not in direct contact with the blood,' said lead researcher Dr Peter Walker. 'Pacemakers electrically stimulate the heart to beat, but our device would work mechanically, allowing the heart muscle time to rest and even, in some cases, repair itself.'"
Sources: University of Leeds news release, February 13, 2008; and various websites
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