Why 3D printing heart valves are the future
Over the next few decades, there will be an incredible demand for this kind of surgery and will probably increase in many parts of the world. Due to the increase in the aging population, lack of workout, and poor diet. It's estimated that around 850,000 people would need implant valves in 2050. Doctor's today are searching for an alternative to replace heart valves currently in use. Unlike conventional heart valves, the silicone heart valve will be custom made to be more precisely to the patient. Doctors will first determine the individual shape and size of the leaky or damaged heart valve using computer tomography or resonance imaging. This makes it possible to print a heart valve that matches the patient’s heart chamber perfectly. Medical researchers use the pictures to make a digital model calculate before the forces working on the implant and its potential deformation. The type of material used is additionally compatible with the body, while the blood flow through the heart valve is nearly as good as conventional replacement valves. Heart surgeons have traditionally used implants that consist either of mechanical or tissue-engineered valves (from cows or pigs) combined with metal frames. To stop the body rejecting these implants, patients need to take life-long immunosuppressants or anticoagulants, which have significant undesirable side effects and not only that may need to have multiple surgeries years after the initial valve.
More efficient...
One of the main problems with conventional replacement valves used today is that they have a rigid geometric shape, making it challenging for surgeons to make sure a stable seal between the new valves and therefore the cardiac tissue. The aorta comes in different shapes and sizes in everyone and using the current valves today makes it quite challenging to find a match. The new class of silicone heart valves provides surgeons an easier solution. Doctors are able to easily customize it to fit the patient perfectly. Thanks to the 3D printer it now takes surgeons about an hour and a half to have the valve ready. On the other hand, it takes several days to form a man-made heart valve by hand from bovine material. With 3D printers production could also speed up the demand and produce dozens or perhaps multiple valves daily. Another reason silicon valves are more efficient is because utilizing radiographic images, scientists have created a digital model to simulate the forces that will act on the silicon implant. This allowed them to judge any potential threats to break and the way the implant would interruption. Furthermore, facilitating blood flow furthermore as other replacement valve materials, silicon is totally biocompatible. Standard replacement valves use hard polymers, metal frames, or animal tissues that pose a chance of rejection. Patients often take life-long immunosuppressants or other drugs to forestall the rejection of those implants. With the silicone implant, this might not be a difficult.
How the valve is made
To begin with, experts will create a negative impression of the valve. They will spray silicone ink onto this impression within the shape of a three-pointed crown, which forms the valve’s thin flaps. Next step, an extrusion printer deposits tough silicone paste to print specific patterns of thin threads on their surface. These correspond to collagen fibers that withstand natural heart valves. The silicone threads reinforce the valve flap and extend the lifetime of the replacement valve. The scientist will print the foundation of the vessels attached to the heart valve using the equal procedure and at the top, they cover it with a net-shaped stent, which is important for connecting the silicone valve replacement to the patient’s circulatory system. Initial tests have produced very assuring results for the new valve’s function. The scientists’ major goal is to increase the lifetime of these replacement valves to 10-15 years. This will be how long current models last in patients before they have to be exchanged.
Risks of 3D printing
- Restricted build size- 3D printers currently have small print chambers which restrict the dimensions of parts which will be printed. Anything bigger will must be printed in separate parts and joined together after production which will increase costs.
- Post processing- Although large parts require post-processing, most 3D printed parts need some kind of cleaning up to get rid of support material from the build and to smooth the surface to attain the desired finish. Post processing methods used include waterjetting, sanding, a chemical soak and rinse, air or heat drying, assembly et al.. the number of post processing required depends on factors including the scale of the part being produced, the intended application and also the sort of 3D printing technology used for production. So, while 3D printing allows for the fast production of parts, the speed of manufacture is slowed by post processing.
- Design inaccuracies- 3D printing is directly associated with the kind of machine or process used, with some printers having lower tolerances, meaning that final parts may differ from the initial design. this will be fixed in post processing, but it must be considered that this may further increase the time and value of production.
- Large volumes- 3D printing may be a static cost unlike more conventional techniques like injection moulding, where large volumes could also be more cost effective to supply.
- Part structure- 3D printing (also referred to as Additive Manufacturing) parts are produced layer-by-layer. Although these layers adhere together it also implies that they will delaminate under certain stresses or orientations. This problem is more notable when producing parts utilizing combined deposition modeling, while polyjet and multijet parts also tend to be more brittle.
Harvard's 3D printed heart valves
A team at Harvard amongst other collaborators have tested 3D printed heart valves which has and had a 75% success rate. Their 3D heart valve model came complete with aortic walls, calcium deposits, and leaflets. They were also able to create a "sizer" which is placed inside the model that can expand or contract until the perfect fit is found. Also using thin pressure- sensing film wrapped around it like a guide. The team then tested out the new technology using data from 30 patients who had previously undergone TAVR procedures, exactly half which went on to develop leaks as a result of the valves being undersized. Comparing the best valve size for every patient to those they received revealed that only 60 percent had gotten the proper size, and also the team was ready to successfully guess the leaky outcomes with a success rate between 60 to 73 percent. These types of insights can help clinicians decide before time which patients will enjoy TAVR procedures, and which are more complicated cases that will be more comfortable choosing heart surgery.
Will it ever be on the market?
Unfortunately, it'll still take a minimum of 10 years before the new implant valves to acquire clinical use, as they first must endure exhaustive clinical trials and be approved by the FDA. However, either an industrial partner or possibly a spin-off is required to create the heart valve commercially available on the market.
References
- “Custom 3D-Printed Heart Valves Fit Perfectly.” Futurity, PETER RÜEGG-ETH ZURICH, 23 July 2019, www.futurity.org/heart-valves-3d-printing-2112122/.
- Wyss Institute, and Harvard University. “Harvard's 3D-Printed Heart Valves Open the Door to a Perfect Fit.” New Atlas, Nick Lavars, 11 Dec. 2018, newatlas.com/harvard-3d-printed-heart-valve/57600/.
- Jack Carfagno. “3D Printed Replacement Heart Valves Potentially Saving Lives.” Docwire News, Jack Carfagno, 24 July 2019, www.docwirenews.com/docwire-pick/3d-printed-replacement-heart-valves-potentially-saving-lives/.
- “3D Printing a Human Heart Valve.” National Institutes of Health, U.S. Department of Health and Human Services, 9 Oct. 2019, directorsblog.nih.gov/2019/10/10/3d-printing-a-human-heart-valve/.
- Unsplash. “Best 100 Medical Pictures [HQ]: Download Free Images & Stock Photos on Unsplash.” Best 100 Medical Pictures [HQ] | Download Free Images & Stock Photos on Unsplash, unsplash.com/s/photos/medical.