by Approximately 50% of patients using ventricular assist devices (VAD) experience infections due to the thick cable used for power supply. However, researchers from ETH Zurich have created a solution to address this problem. The team, led by engineer Andreas Kourouklis, collaborated with physicians from the German Heart Center in Berlin and ETH Zurich Professor Edoardo Mazza to develop a new cable system for VADs that reduces the risk of infection. The findings have been published in the journal Biomaterials Advances.
For patients awaiting a heart transplant, VADs are often the only option for maintaining a decent quality of life. These devices require the same amount of power as a television and are powered by an external battery connected via a seven-millimeter-thick cable. While this system is reliable, the point at which the cable exits the abdomen is susceptible to bacterial breach, even with medical treatment.
Kourouklis aimed to eradicate this issue by developing a cable system that does not cause infections. Wireless methods of power transmission are not yet available to patients, making this solution particularly vital. He received a Pioneer Fellowship from ETH Zurich to further advance this technology.
The current thick cable used in VADs hinders the wound healing process and greatly impacts patients’ quality of life. Scar tissue forms around the exit point, impairing the skin’s ability to heal and heightening the risk of infections. The loose attachment of the outer skin layers to the flat surface of the cable allows bacteria to penetrate deeper tissue layers, resulting in frequent infections and rehospitalizations.
To combat this, the ETH Zurich researchers developed a technology that replaces the thick cable with several thin and flexible wires with a rough, irregular surface. The team compared this approach to how human hair can penetrate the skin without causing infections. The use of more flexible wires with microscopic craters facilitates the healing of the skin.
To create the craters, the engineers at ETH Zurich devised a process that enables the formation of small, irregular patterns on non-flat surfaces. This patented method involves coating the flexible cables with a thin layer of silicone and cooling them to -20°C. The malleable surface of the cables is then exposed to a condensation chamber where water droplets create microscopic craters in the silicone layer. By controlling the humidity and temperature in the chamber, the researchers can determine the placement of the craters on the cables.
The size of the craters is crucial, as they cannot be too large or too small. Large craters may harbor bacteria, increasing the risk of infection, while small craters do not adhere to the skin and allow inward growth, also raising the risk of infection. To address this issue, Kourouklis and his team employed computational and experimental methods in tissue biomechanics and biomaterials.
Initial tests on skin cell cultures and subsequent trials on sheep demonstrated promising results. The thin, flexible cables with craters only exhibited mild inflammatory reactions, while the sheep’s skin integrated well with the cables and there were no infections. Although further tests on animal and human subjects are required before the technology can be used on heart patients, Kourouklis is optimistic about bringing this solution to market as soon as possible. He is currently collaborating with medical device engineers and heart surgeons to enhance the cable system.
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1. Source: Coherent Market Insights, Public sources, Desk research
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