AsianScientist (Oct. 16, 2015) – Researchers have developed a prosthetic heart valve that can be inserted in a minimally invasive operation, giving patients that require mitral valve replacements an alternative to open heart surgery.
Heart valves are thin flaps of tissue in the heart, which ensure unidirectional flow of blood between the four chambers during the cardiac cycle. The mitral valve is one of the four valves in the human heart.
When the mitral valve malfunctions and does not close all the way, blood flows backward into the upper heart chamber (atrium) from the lower chamber as it contracts. This cuts down on the amount of blood that flows to the rest of the body. As a result, the heart may try to pump harder, and this may lead to congestive heart failure or it may worsen an existing heart failure.
Some 12 million people suffer from mitral regurgitation worldwide, with nearly 250,000 new patients diagnosed annually. Left untreated, one in three patients with severe form of the condition will die within six years. Although current mitral valve interventions delivered via a small incision through the skin could be a viable alternative treatment, this strategy benefits only a highly selective group of patients who have mitral valve leaflets of a particular shape.
Instead, a team from the National University of Singapore led by Associate Professor Leo Hwa Liang and Dr. Jimmy Hon have designed a valve that can be tailored to each patient before implantation. Called VeloX, the device comprises a prosthetic heart valve made of pericardial tissue ‘stitched’ within a self-expanding, polymer-coated nickel-titanium (nitinol) alloy stent frame specially designed to prevent leakage.
To implant the device, the prosthetic valve is compressed to the thickness of a pencil and loaded into a catheter. The catheter is inserted into the patient through a small incision made either at the leg or between the ribs to deliver the device straight into the left heart. The catheter will then be used to send the device to the patient’s diseased mitral valve. To facilitate accurate placement, the device is designed to be retrievable and repositionable.
“The mitral annulus has a very complex structure, so it is particularly challenging to deploy and anchor a prosthetic valve into the constricted region. Optimal positioning is crucial as any malpositioning can be detrimental for patients. One of the unique features of VeloX is its ability to be self-centring, hence enabling it to achieve an optimal position after being implanted,” Leo said.
“VeloX will restore the unidirectional flow of the blood in the left heart and help alleviate the symptoms associated with mitral regurgitation. This transcatheter valve offers palliative treatment for the patients who were denied surgery, especially those with multiple co-morbidities,” Hon added.
Building on the encouraging results from the earlier phases of the project, the team is now refining the design of the existing device. The team plans to conduct in vivo studies to acquire data on the technical performance of the device.
The researchers have filed a patent for the device, and are planning to set up a spin-off company. They hope to work with medical technology companies to commercialise their invention to benefit patients soon.
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Source: National University of Singapore.
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