Design, Development and Preliminary Validation of a Leaflet Excision Device for Transcatheter Aortic Valve Replacement

TAVR (Transcatheter Aortic Valve Replacement) is a minimally invasive procedure for the treatment of aortic stenosis, involving the implantation of a bioprosthetic aortic valve. However, when the newly implanted valve displaces the underlying valve leaflets outward, coronary artery obstruction remains one of the most common risks. To address this, several techniques and experimental devices have been developed with the aim of modifying the aortic valve before TAVR to ensure unobstructed blood flow through the coronary arteries. Electrocautery is the most widely used technology in the current research device. However, the use of electrical energy may interfere with the heart’s electrical conduction system. The aim of this thesis is the design and development of an innovative device that excises part of the diseased aortic valve ensuring post-TAVR coronary blood flow with a purely mechanical technique without the risks associated with electrocautery. The device consists of movable and a fixed jaws and employs a multiple-blade system to remove a rectangular portion of tissue. The front blade is used for penetrating and cutting the short side and the lateral blades for cutting the long sides of the rectangle. The device’s actuation is cable-driven and manually controlled. Additionally, the device is designed to ride on a guidewire that can be directly positioned inside the coronary artery. The study initially focuses on the design of the open-close mechanism and cutting modality. Subsequently, each component is fabricated using 3D printing, miniaturised custom blades are cut by electrical discharge machining, and the device is then easily assembled. An iterative refinement process of design, fabrication and assembly is carried out to determine the optimal component dimensions, tolerances and force transmission mechanisms. A bench test is then performed to measure the force required to penetrate a tissue simulating the thickness and mechanical properties of the aortic valve. The blade shape that applies the widest cut with the lowest force is identified among four possibilities: triangular, circular, rectangular and pentagonal. Finite element analysis is also performed to evaluate the structural integrity and strength of the closing mechanism and to further optimize the design. Finally, interventional cardiologists assessed the usability and acceptability of the device. Results show that the device can penetrate with minimal force when using a triangular blade shape. Additionally, the action of the multiple-blade system results in the precise excision of a rectangular tissue area. These findings suggest that the proposed mechanical approach could provide a safer alternative to electrocautery while maintaining coronary patency.