Steerable Catheter Tip Section Asymmetric Deflection Mechanism
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Solution Overview
Problem
Steerable catheters, particularly bidirectional ones, face challenges in maintaining precise in-plane deflection due to the flexible nature of their tip sections, which often leads to unwanted out-of-plane deflection.
Innovation Solution
The catheter incorporates a deflection mechanism with a cross-section that has a greater area moment of inertia about one centroidal axis and a lesser area moment about an orthogonal axis, biasing the tip section to deflect in the plane with the greater moment of inertia and resist deflection in the plane with the lesser moment of inertia, achieved through a configuration with unequal dimensions such as a rectangular cross-section with a thicker and thinner dimension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the tip section is made of flexible material to enable deflection, then the catheter can be steered, but out-of-plane deflection becomes difficult to limit
Solution Approach 1:
The deflection mechanism employs an asymmetric cross-sectional geometry with unequal area moments of inertia about two orthogonal centroidal axes. The first centroidal axis has a greater area moment of inertia while the second centroidal axis has a lesser area moment of inertia, creating inherent directional bias in the flexible tip section that promotes deflection along a specific plane while resisting out-of-plane deflection.
2Adaptability or versatility
If a bidirectional steerable catheter is designed with two puller wires, then deflection in two opposing directions is achieved, but control precision in the desired plane is reduced due to out-of-plane deflection
Solution Approach 1:
The deflection mechanism employs an asymmetric cross-sectional geometry with unequal area moments of inertia about two orthogonal centroidal axes. The first centroidal axis has a greater area moment of inertia while the second centroidal axis has a lesser area moment of inertia, creating inherent directional bias in the flexible tip section that promotes deflection along a specific plane while resisting out-of-plane deflection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the catheter's ability to maintain in-plane deflection, providing precise control and resistance to off-plane deflection, thereby improving the catheter's stability and effectiveness in navigating the heart's chambers.
Implementation Method 1
The deflection mechanism is elongated to extend longitudinally along the tip section and has a cross section that provides a lesser area moment of inertia about a first centroidal axis and a greater area moment of inertia about a second centroidal axis generally orthogonal to the first centroidal axis
Data Source
AI summary
An improved steerable catheter with in-plane deflection comprises a catheter body having proximal and distal ends and a lumen extending therethrough and a tip section at the distal end of the catheter body. The tip section comprises a flexible plastic tubing having a pair of diametrically-opposed lumens extending therethrough. The catheter also provides two puller wires manipulated through a control handle at the proximal end of the catheter body. Each puller wire extends through one of the pair of lumens in the tip section and through the lumen of the catheter body and is anchored to the control handle at its proximal end and anchored to the tip section at its distal end. The deflection mechanism is configured to generally define a plane along which deflection most readily occurs and an edge along which deflection is most readily avoided. The deflection mechanism extends longitudinally along a centerline of the tip section between the first and second puller wire and is configured generally with a cross section having a thinner dimension and a thicker dimension to bias the tip section to deflect in a plane parallel with the thinner dimension of the deflection mechanism and to resist deflection in a plane perpendicular to thicker dimension.