Scientists develop customised heart valves

Zurich, Switzerland - Researchers at Swiss science & technology university ETH Zurich are collaborating with South African company Strait Access Technologies (SAT) to 3D print custom-made artificial heart valves from silicone.

Created in “several steps”, the new model can be tailored more precisely to the patient, compared to conventional heart valves.

While at least a decade away from coming into clinical use, the new valves have demonstrated “very promising results” in initial tests, according to a report by ETH.

As part of the process, the researchers first determine the individual shape and size of the leaky heart valve using computer tomography or magnetic resonance imaging.

This makes it possible to print a heart valve that perfectly fits the patient’s heart chamber.

The researchers use the images to create a digital model and a computer simulation to calculate in advance the forces acting on the implant and its potential deformation.

The material used is also compatible with the human body, enabling mechanical matching with the host biological tissue.

Traditional implants consist either of hard polymers or animal tissue combined with metal frames. To prevent the body rejecting these implants, patients have to take life-long immunosuppressants or anticoagulants.

In addition, the silicone alternatives address the conventional implants’ issue of rigid geometric shape, which make it challenging for surgeons to ensure a tight seal between the new valves and the cardiac tissue.

“The replacement valves currently used are circular, but do not exactly match the shape of the aorta, which is different for each patient,” explained Manuel Schaffner, one of the study’s lead authors and professor for complex materials at ETH.

The new valves take about an hour and a half to produce with a 3D printer, whereas traditional valves take several working days to make.

Prior to the 3D printing process, the scientists create a negative impression of the valve.

Silicone ink is sprayed onto this impression in the shape of a three-pointed crown, which forms the valve’s thin flaps.

In the next step, an extrusion printer deposits tough silicone paste to print specific patterns of thin threads on their surface. These correspond to collagen fibres that pass through natural heart valves.

The silicone threads reinforce the valve flap and extend the life of the replacement valve.

The root of the blood vessel connected to the heart valve is printed using the same procedure and at the end is covered with a net-shaped stent, which is needed for connecting the silicone valve replacement to the patient’s cardiovascular system.

Following up the initial favourable test results, the scientists are currently working on extending the life of these replacement valves to 10-15 years, the life span of current models available.

“It would be marvellous if we could one day produce heart valves that last an entire lifetime and possibly even grow along with the patient, so that they could also be implanted in young people as well,” Schaffner said.

In order to reach commercial-level production, the project will require an industrial partner or possibly a spin-off.

“As a research group, we are unfortunately unable to provide a seamless offering from the first experiment to the first application in the human body,” Schaffner concluded.