3D Rapid Prototyping and Prosthetic Mitral Valve Design

Heart diseases lead to a large number of deaths globally.Some of these diseases can be a result of mechanical, electrical, or biochemical complications within the heart.Among heart valve diseases, mitral valve diseases are common.A diseased mitral valve negatively affects the amount of blood that fills the left ventricle, thus decreasing cardiac output.It is reported that over 2 million Americans suffer from mitral valve regurgitation, and a large number of patients suffer from Rheumatic heart disease, leading to mitral stenosis in over 3 million patients.While the mitral valve can be repaired in many cases, surgical replacement of the valve with a prosthetic valve is often performed.Prosthetic heart valves are used to replace the diseased mitral valve, allowing the patient's heart to function regularly.Before a prosthetic is utilized, it goes through a design process.The design of a prosthetic valve can be accomplished by collaborative work involving different disciplines.The objective of the present undergraduate research project is to design a prosthetic mitral valve, involving collaborative effort of biomedical and mechanical engineering students, employing CAD and 3D printing and prototyping a prosthetic mitral valve.The requirements for a prosthetic mitral valve are to match the structure and function of the natural mitral valve.Literature on structure of existing mitral valves, including the caged ball valve, single disc valve, bi-leaflet valve, and the tilting disc valve were reviewed.Each configuration of the prosthetic mitral valve had its advantages and disadvantages.Considering functional similarity with the natural valve, a bi-leaflet valve configuration was selected.The design process began with concept sketches of the mitral valve.Through the collaborative team of biomedical engineering and mechanical engineering students, integrating the knowledge of the anatomical and physiological aspects of the heart chambers and valves with computer aided design techniques such as SolidWorks, a 3D model of the mitral valve was created based on the conceptual design.After iterative design reviews and corresponding improvements, the design was finalized.The components of the final design of the prosthetic mitral valve consisted of a holding ring (20 mm diameter and 4mm thickness) and a suture ring (22 mm diameter).The leaflets (10 mm diameter) were hinged within the holding ring.3D drawings and .STL files were prepared to provide input to 3D Printing machine.Based on iterative improvements in valve design, a few prototypes of the 3D model were fabricated using 3D rapid prototyping.Upon examining the fourth version prototype of the prosthetic mitral valve, the feasibility of the approach was shown.In the future, it is hoped to explore the development of an enhanced mitral valve using flexible material.It is also hoped to develop a mitral valve suitable for a minimally invasive method for implantation, such as a transcatheter technique.In conclusion, with a collaborative team of biomedical and mechanical engineering students, a prosthetic mitral valve was designed using 3D CAD tools.Design reviews, iterative improvements, and corresponding 3D rapid prototypes were made.The feasibility of the design and fabrication approach illustrated the achievements of learning outcomes through this research project, supporting the idea of increasing collaboration and research at undergraduate levels.