Catheter with Improved steerability for the TAVI Procedure

Design, Development and Validation

Master thesis (2017)

Authors

L. Schouten Mechanical Engineering

Contributors

J.J. van den Dobbelsteen (supervisor 1)
J. Dankelman (supervisor 2)
R. Mugge (supervisor 2)
Faculty
Mechanical Engineering
Copyright: © 2017 Luuk Schouten
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Published Date

22-09-2017

Language

English

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Faculty

Mechanical Engineering

Abstract

Aortic stenosis is one of the most serious heart valve diseases and is the result of calcification of the aortic valve leaflets. This calcification is irreversible and affect the functionality of the heart valves. The only treatment is an aortic valve replacement. The trend in heart valve replacement is moving from open heart surgery towards minimally invasive techniques where a heart valve prosthesis is placed over the native aortic valve, called the TAVI procedure.

A crimped stent that contains a heart valve prosthesis is pushed upwards through the femoral access route with a delivery catheter. This prosthesis is placed in the aortic annulus and wedged over the native valve. The positioning of the heart valve prosthesis is important for the success of the procedure and durability of the prosthesis. A coaxial placement to the aortic annulus in the center of the aorta lumen is the target during this positioning of the prosthesis.

The Medtronics and Edwards delivery systems, that are currently used, only have the possibility to be steered with a maximum of 1 rotation, providing an alignment with the aortic annulus in the frontal plane of the body. The rotation to provide the alignment in the sagittal plane is lacking. This report will focus on the question if extra steerability of the delivery system will provide a better positioning of the tip of the delivery system, which in the end, will position the heart valve prosthesis.

The Edwards delivery system will be reverse engineered to look at the current mechanisms that are used to provide the rotation in the frontal plane. Subsequently, two experiments are performed to select the best configuration for the modification on the tip of the delivery system. Ultimately, the designed prototype will be validated with two tests to answer the research question if the extra steerability will provide a better positioning.

The prototype is validated by comparing the positioning of the Medtronics and Edwards delivery system with the prototype during an experiment where the three systems have to be maneuvered to a predefined position in an aorta model of glass. This predefined position represents the center of the aorta lumen in a coaxial orientation. Two rotations and the xyz-coordinations of the tip will be measured by an Aurora NDI system and the results will be compared.

It showed that the prototype provided a bigger reach within the aorta lumen and a had a bigger domain of angles in which the tip could be orientated than the prototype. Moreover, the prototype provided a better alignment in the sagittal and frontal plane with regards to the reference point.

The research only focused on the positioning of the tip and didn’t take the deployment of the heart valve prosthesis into account. Further development of the prototype is needed to make it useful for the TAVI procedure. In addition, more research is needed to validate the prototype in a dynamic environment that represents the reality with blood flow and more tortuosity in the access route. Nevertheless, the prototype look promising to be used for the perfect positioning of the heart valve prosthesis which will have a positive effect on the durability and functionality of the prosthesis.