Catheter Shaft Metal Braid Torque Transmission
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Solution Overview
Problem
Conventional catheters with resin braids over their entire length or with resin and metal braids at different ends suffer from inadequate torque transmission properties and are prone to kinking, with difficulties in processing the distal end for lead wire insertion and risk of insulation damage.
Innovation Solution
A catheter with a catheter shaft reinforced by a metal braid over its entire length, featuring side holes formed without cutting the metal braid, allowing lead wires to pass through the braid mesh without contact, filled with resin to prevent damage, and maintaining a G/d value of 1.2 or greater for effective torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the catheter shaft is reinforced by a resin braid over its entire length, then the catheter can be manufactured more easily, but the torque transmission properties are insufficient
Solution Approach 1:
The catheter shaft employs a composite structure combining resin braid and metal braid layers. The resin braid provides flexibility and ease of manufacture, while the metal braid enhances torque transmission properties. This composite material approach resolves the contradiction by integrating the advantages of both materials.
Solution Approach 2:
The metal braid is positioned at specific locations within the catheter shaft structure where torque transmission is most critical. This localized reinforcement strategy improves torque transmission properties without requiring the entire shaft to be made of metal, thus maintaining ease of manufacture.
2Reliability
If the catheter shaft is reinforced by metal braid at the distal end portion, then the torque transmission properties are improved, but it becomes difficult to process the tube wall to form side holes
Solution Approach 1:
The catheter shaft structure places the metal braid layer internally while forming side holes through the outer resin layer. This local quality differentiation allows side holes to be processed easily through the resin exterior while the internal metal braid remains intact to provide torque transmission reinforcement.
Solution Approach 2:
The catheter shaft is segmented into functional layers: an outer resin layer that facilitates easy side hole processing, and an internal metal braid layer that provides torque transmission. This segmentation allows each layer to perform its specific function without interfering with the other.
3Ease of manufacture
If the metal element wire is cut to form side holes, then side holes can be formed in the tube wall, but the cut surface of the metal wire may damage the lead wire insulation
Solution Approach 1:
The side holes are formed exclusively in the resin layer of the catheter shaft, not in the metal braid layer. This local quality differentiation ensures that the metal element wires remain unc uted and intact, preventing any damage to lead wire insulation while still allowing side holes to be formed for lead wire passage.
Solution Approach 2:
The catheter shaft wall is segmented into an outer resin portion and an inner metal braid portion. Side holes are formed only in the resin portion, allowing lead wires to pass through without contacting or damaging the metal wires. This segmentation protects the lead wire insulation while maintaining manufacturing feasibility.
4Ease of operation
If the proportion of resin in the catheter shaft is increased to accommodate the guide wire lumen, then the guide wire can be inserted easily, but the torque transmission properties deteriorate
Solution Approach 1:
The catheter shaft uses a composite structure with resin and metal braid layers. The resin component provides flexibility and accommodates the guide wire lumen for easy insertion, while the metal braid component compensates for the reduced resin proportion by providing the necessary torque transmission properties.
Solution Approach 2:
The metal braid is strategically positioned within the catheter shaft structure to provide localized reinforcement for torque transmission. This allows the overall resin proportion to remain high for guide wire compatibility, while specific regions have enhanced mechanical properties for torque transmission.
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
An object is to provide a catheter that excels in torque transmission properties, that makes it easy to process a distal end portion of a catheter shaft to form a side hole therein, and that does not allow a lead wire that is inserted in a side hole to be damaged. The catheter (100) includes a shaft (10), ring-shaped electrodes (201 to 210) that are mounted at an outer peripheral surface of a distal end portion of the shaft (10), and electrode lead wires (301 to 310), wherein the shaft is made up of a braid (183) that is embedded in a tube wall over an entire length of the shaft, the braid (183) being formed from a metal element-wire bundle (181), side holes (15) are formed in a tube wall of the distal end portion of the shaft without cutting the metal element-wire bundle, a distal end portion of each lead wire is joined to an inner peripheral surface of each electrode, and the lead wires are inserted into the side holes and thus pass through meshes of the braid and enter a lumen of the shaft, and the side holes in which the lead wires are inserted are filled with a resin material (16), and, when the diameter of the lead wires is d and the diagonal length of the meshes of the braid is G, a G/d value is 1.2 or greater.