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Heart Valve
ME 445 (Introduction to Biomechanics) was a class offered in both the Mechanical Engineering Department as well as the Bioengineering Department. For the final project in this class my team chose to come up with a new design for an artificial heart valve. There are several problems with the current designs that are used. One design which uses a caged-ball to restrict flow in one direction has flow problems and clotting issues. The other common design which uses an off-center axis tilting disc tends to fail from repetitive impact to the strut that restricts movement of the disc, causing the strut to break.
For this project, I worked on the design components. The new designs were created while considering the design of a real human heart valve and the problems of the current designs. Two images of the first design are shown below, the first is from the design file in SolidWorks and the second is a photorealistic render.
The first design was created to mimic a real heart valve by using a leaflet design. The three leaflets would be made from heparin-coated silicone. Silicone was chosen because it is mostly inert and is used on current heart valve designs. Heparin is a biological molecule that can be used as a coating on implantable materials to reduce the chance of blood clotting. The frame would be made from pyrolytic carbon, which is a biocompatible material used in current heart valves. The frame of the first design was designed to restrict as little blood flow as possible. The purpose of the center component of the frame was to allow the silicone leaflets to seat against the frame to reduce the chance that they would fail by opening in the opposite direction.
The second design was created without the center portion of the frame. This was done to reduce design complexity and also reduce the surface area of the heart valve, which would reduce the chance of blood clotting. Two images of the second design can be found below, one of the design in SolidWorks and another which is a photorealistic image of the design.
One potential problem with the second design is that there would be a higher chance of the silicone leaflets inverting because there was not a rigid material for them to seat against. Because the leaflets inverting would most likely result in patient death, a final design was created to reduce the risk of this happening. An image of the design is shown below.
The final design is similar to the first but uses a redesigned center portion which offers a larger surface area for the leaflets to seat against. While a larger surface area does increase the chance of blood clotting, it was decided that was an acceptable risk to reduce the chance of leaflet inversion. This valve would use the same materials as the previous designs. A photorealistic image of the final design is shown below next to an image of a model that was built out of ABS and silicone using the Stratasys Dimension 3D Printer.
The biggest potential problem with these new designs is that the silicone portion of the valve could fail after repetitive movement.
Team members: David Desmarais, Kristen Trett
Page created: 2010