Concordia researchers have developed a technique to detect obstructions in a type of mechanical heart valve that they believe can contribute to safer follow-up methods for cardiologists and their patients.
The team led by Lyes Kadem, professor in Department of Mechanical, Industrial and Aerospace Engineering to the Gina Cody School of Engineering and Computer Science, published their results in the journal Artificial organs. Doctoral candidate Ahmed Darwish was lead author and Giuseppe Di Labbio, assistant professor Wael Saleh and Othman Smadi of Hashemite University in Jordan contributed.
The researchers used high-tech equipment to examine the downstream flow of a two-sheet mechanical heart valve (BMHV). The equipment included a tailored dual-activation left cardiac duplicator designed and created in their laboratory by Concordia college students, a high-speed camera and a laser.
Despite its imposing name, the BMHV is a simple ring with an internal diameter of about 2.5 cm. Two carbon-based leaflets inside the ring open and close as the heart pumps blood from the left ventricle and into the aortic arch, which sends blood into the body.
They replace the damaged aortic valves and are installed by open heart surgery. A blocked BMHV can be catastrophic.
Blood flow mapping
The method the team designed simulated blood flow patterns resulting from six different heart valve blocks. The researchers photographed particles immersed in a liquid that mimics blood and pumped the fluid through the heart duplicator.
Using a technique called velocimetry of particle images, were able to determine the flow velocity. It allowed them to simulate the flow of blood with the leaflets completely free of obstruction, when they were partially obstructed and completely blocked.
"Imagine being outside a stadium and the crowd moving away from three gates one next to the other," says Kadem, the Concordia Research Chair for cardiovascular engineering and medical devices.
"If the gates are open, you will see a uniform distribution of people coming out of all three openings. If a gate is closed, you will see more people starting from the other two and none from the closed one. Therefore, we will deduce that c & # 39; it's a block. "
When applied using phase-contrast magnetic resonance (MRI), the method is both non-invasive and radiation-free, says Kadem. This means that doctors can use it for the detection of BMHV dysfunctions and follow-up.
"Currently, the ultrasound is the best way to detect valve dysfunction," he says. "The next step is the cinefluoroscopy, which uses radiation. It is not possible to use this method as a follow-up because it exposes the patient to radiation and increases the risk of cancer."
Darwish and Kadem note that artificial heart valves are generally safe but are not risk free. C is a probability between 0.1% and 6% of dysfunctions that can occur between one hour and 20 years after the replacement of the biological valve. These can be fatal, with a mortality rate of 28.6% when a dysfunction causes an emergency.
This research is supported by a scholarship from the Research Council of Natural Sciences and Engineering of Canada.
Read the cited document: Experimental investigation of the downstream flow of a dysfunctional bileaflet mechanical aortic valve.
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