Redesign of the Aortic Heart Valve Prothesis: Parametrically Programmable Geometry, Personalized Technology and Mechanics Discussion

Abstract

With the improvement of the living conditions and life expectancy, the incidence of the structural heart disease, represented by aorta valvular disease, is expected to increase as well. Aorta valve replacement is the most promising treatment to the aorta valvular disease. Even though the mechanics of the aorta valve has not been clear enough (i.e. the mechanism of valve’s movement, reasons for the degenerated valve disease like calcification and thrombus, etc.), it is proved in years of practice and could be indicated that the transvalvular aorta valve replacement (TAVR) and bio-prothesis would be the mainstream of the aorta valve replacement surgery.

Additive manufacturing, also known as 3D printing, performs noticeably in personalized medical devices. The mechanism of additive manufacturing theoretically permits the rapid manufacturing of a series of similar geometries which might created by a same geometry model with different parameters without complex technology adjustment (i.e. complex programming in CNC machine, remanufacturing of the reconstruction of the mold model, etc.)

Firstly, further exploration towards the aorta valve would face a series of restrictions like medical ethics and confidential problems, as well as in the manufacturing of the aorta prothesis. Therefore, parametrical geometry models have been introduced in the construction work of aorta valve’s morphology. Data sets labelled by the featured dimensions with concrete physical or medial meanings captured by the Computed Tomography (CT) have been carefully adapted into the model as reference. The asymmetry of natural aorta valve, including the valve’s positions, special dimensions (i.e. the difference of base diameter and the virtual ring) and the gradient thickness, has been considered and constructed. A relatively standard geometry that most commercial aorta prothesis share has also been constructed as blank group for the later test.

Then the prothesis components are mostly made by hybrid manufacturing after attempts. The series of geometries have been remade to printable mold model for a better manufacturing quality, and the commercial silicone gel has been adapted as the main material of the prothesis’s cusps. After the tensile strength tests have been conducted to the standard samples of the silicone gel with the results that the silicone gel could fit the young’s modules requirements of the artificial cusps, biaxial tests have been conducted to the cusps’ samples. It turns out that the biaxial anisotropy of the natural cusps’ young’s modules could be realized with our geometry model and manufacturing technology.

In order to further evaluate the feasibility of the above geometry model, manufacturing technology and redesigned prothesis, pulse tests have been introduced to test the hemodynamic properties suggested by ISO standards of the prothesis. Based on the results of the preliminary tests, geometry models and the manufacturing technology have been further optimized to produce the samples with thinner thickness. Also, the stent of the demonstrative prothesis has been optimized and remanufactured by additive manufacturing to complete the pulse tests. The demonstrative aorta valve prothesis basically completes testing requirements and leave experience about the key in the manufacturing process. And the tests results have revealed another review towards the geometry-dimensions-to-hemodynamic-properties of the aorta valve and aorta valve prothesis. This might help in the understanding of aorta valve disease.

Date of Award	17 Aug 2026
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Jian LU (Supervisor)