Telescope Catheter Drive Cable Segmentation
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Solution Overview
Problem
Current intravascular ultrasound (IVUS) catheters face issues with telescopic section design, including lumen collapse, drive cable folding, high friction, and increased cost due to complex assembly, leading to mechanical defects and image artifacts.
Innovation Solution
The catheter design incorporates a drive cable with a proximal rigid section and a distal flexible section, where the rigid section is constructed from stainless steel and bonded to the flexible drive cable, and a telescopic section with a thicker outer tubular member to prevent lumen collapse and ensure straight extension/retraction, reducing friction and part count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a thin-walled telescopic section is used to reduce friction and simplify assembly, then ease of manufacture and friction are improved, but the lumen collapses and drive cable folding occurs under compression
Solution Approach 1:
The drive cable is segmented into a proximal rigid section and a distal flexible section. The rigid proximal section provides structural support to prevent lumen collapse during telescopic compression, while the flexible distal section maintains navigation capabilities. This segmentation resolves the contradiction by distributing structural support functions to where they are most needed without compromising overall catheter flexibility.
Solution Approach 2:
The outer tubular member of the telescopic section is thickened locally at the proximal end where compression forces are greatest. This localized thickening provides structural reinforcement to prevent lumen collapse and drive cable folding during telescopic retraction, while maintaining thin walls in other areas to minimize friction and simplify assembly.
2Reliability
If a complex telescopic design with multiple components is used to prevent lumen collapse, then structural integrity is improved, but device complexity and assembly cost increase
Solution Approach 1:
The drive cable is merged with the telescopic section structure by bonding the rigid proximal section directly to the outer tubular member. This integration eliminates the need for separate support structures within the telescopic section, reducing component count and assembly complexity while maintaining structural integrity during compression.
Solution Approach 2:
The outer tubular member of the telescopic section serves multiple functions: it provides structural support to prevent lumen collapse, guides the drive cable during retraction, and acts as the telescopic element itself. This multi-functionality reduces the need for additional components and simplifies the overall design.
3Reliability
If the outer tubular member is thickened to prevent lumen collapse, then structural integrity is improved, but friction during telescopic movement increases
Solution Approach 1:
The outer tubular member is thickened only in the proximal region where compression forces are greatest and structural support is most needed. The distal portion maintains thinner walls to minimize friction during telescopic movement. This localized thickening strategy balances structural integrity requirements with operational smoothness.
Solution Approach 2:
The telescopic section is divided into functional zones: a proximal region with thickened walls for structural support and a distal region with thinner walls for reduced friction. This segmentation allows each zone to be optimized for its specific function without compromising the other.
Data Source
AI summary
A catheter has a proximal end and a distal end and comprises an outer tube having a proximal end, an inner sheath slidingly received within the outer tube and extending distally from the outer tube, and a rotatable shaft extending from the proximal end of the outer tube to within the inner sheath. The rotatable shaft is axially fixed with respect to the outer tube and axially moveable within and with respect to the inner sheath. The rotatable shaft includes a proximal substantially rigid section and a distal flexible section. The catheter further includes a working element carried on the distal flexible section of the rotatable shaft.