Degenerative heart valve disease is a growing problem amongst the ageing populations of Europe and the US, while in the developing world valve failures caused by bacterial infections affect tens of millions of people.
As part of a research collaboration that has spanned more than a decade, biomedical engineer Professor Neil Bressloff and interventional cardiologist Professor Nick Curzen, both based at the University of Southampton, have been investigating ways to use engineering to improve heart treatments.
In their latest research, the pair are looking into ways to improve heart valve replacement, particularly in a procedure known as TAVI (transcatheter aortic valve implantation). In this procedure, a metal cage, or stent, is passed over a catheter and into place within the opening of the aortic valve, Bressloff explained.
“When this replacement valve opens up, it pushes the (damaged) heart valve aside, and the prosthesis starts functioning as the native valve would have done,” he said.
The researchers have previously carried out a successful pilot study to investigate the use of additive manufacturing to print these thin strut valve structures. Now, in a new EPSRC-funded project, they are hoping to optimise the additive manufacturing process, known as direct metal laser sintering (DMLS), and assess its effectiveness in producing replacement heart valve frames. The researchers will be working with Italian firm Sisma, which specialises in additive manufacturing of jewellery and dental implants.
“Direct metal laser sintering involves laying down layers of powder, over which a laser is then fired - following a geometry model in a CAD package - to build up the structure,” Bressloff said.
Existing replacement heart valves are typically laser-cut from tubes, in the same way that stents are manufactured, which limits their design. By using additive manufacturing, the researchers hope to explore different design concepts, he said.
For example, the researchers will be looking into the design of valves for use in what is known a redo-TAVI, in which the damaged TAVI valve is itself replaced with a new prosthetic valve.
“TAVI as a procedure was originally trialled on high risk, frail patients who couldn’t undergo open heart surgery, but because of its success the method is being extended to low risk and younger patients, leading to the need for long-term durability of replacement heart valves, as well as procedures such as redo-TAVI,” said Bressloff.
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