Catheter Coil Segmentation for Force Transmission and Followability
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Solution Overview
Problem
Catheters face challenges in followability to curved guide wires and efficient transmission of pushing and rotational forces due to restrictive coil body configurations, leading to poor performance in navigating narrowed or obstructed segments in blood vessels and ducts.
Innovation Solution
A catheter design with a coil body where element wires are not completely fixed to the inner and outer layers, allowing for flexibility and contact at the distal end to improve followability and stiffness at the proximal end for efficient force transmission, along with a cavity between the inner layer and coil body to enhance curvature and rotational force transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the coil body is entirely covered and fixed with the inner layer and the outer layer throughout its length, then the structural stability is improved, but the followability to a curved guide wire deteriorates
Solution Approach 1:
The catheter shaft is divided into multiple sections with different structural characteristics. The coil body is segmented such that it is fixed at certain portions and unfixed at other portions along its length, allowing different regions to serve different functions (stability vs. flexibility).
Solution Approach 2:
Different portions of the coil body have different fixation states. Specifically, the coil body is fixed with the inner and outer layers at proximal portions to provide stability, while remaining unfixed at distal portions to enable curvature and followability to guide wires.
2Force
If the coil body is entirely fixed with the inner layer and the outer layer, then the pushing force transmission is improved, but the rotational force transmission deteriorates
Solution Approach 1:
The coil body fixation is segmented along its length, with fixed portions for pushing force transmission and unfixed portions that allow rotational movement. This segmentation enables both types of force transmission without compromise.
Solution Approach 2:
Different axial portions of the coil body have different mechanical properties: fixed portions provide stiffness for pushing force transmission, while unfixed portions provide rotational freedom for rotational force transmission from the operator to the distal end.
3Adaptability or versatility
If axially adjacent element wires do not come into contact with each other, then the flexibility is improved, but the force transmission efficiency deteriorates
Solution Approach 1:
The spacing between axially adjacent element wires varies along the length of the coil body. At certain portions, the wires are in contact or closely spaced to enable efficient force transmission, while at other portions, they are spaced apart to allow flexibility and curvature.
Data Source
AI summary
A catheter having a proximal end portion having gaps between axially adjacent portions of an element wire where an inner layer is joined to an outer layer through the gaps; and a distal end portion where the axially adjacent portions of the element wire come into contact with each other, and a cavity is provided between the inner layer and a coil body. The catheter has excellent followability to a guide wire and is capable of efficiently transmitting a pushing force and/or rotational force from an operator to the distal end of the catheter.