Tissue-Removing Catheter With Keyed Liner for Guidewire Protection
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Solution Overview
Problem
Existing tissue-removing catheters face challenges in efficiently removing occlusive tissue from body lumens while protecting the guidewire from rotational forces and preventing kinking, particularly in applications like percutaneous coronary angioplasty and stent delivery.
Innovation Solution
A tissue-removing catheter design featuring an elongate body with a rotating drive coil, a tissue-removing element, and an inner liner that defines a guidewire lumen, along with a guide tube and advancer mechanism that allows for non-rotational, translational movement of the inner liner, preventing rotational forces from being transmitted to the guidewire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inner liner is allowed to rotate with the elongate body, then the tissue-removing element can effectively remove occlusive tissue, but the guidewire will experience rotational forces that may cause kinking or damage
Solution Approach 1:
The catheter is divided into independently movable segments: the elongate body with tissue-removing element rotates independently from the inner liner, which moves only translationally through the guide tube. This segmentation allows the tissue-removing element to rotate for effective tissue removal while the guidewire within the inner liner remains protected from rotational forces, preventing kinking and damage.
Solution Approach 2:
The guide tube acts as an intermediary mechanism that constrains the inner liner to translational movement only, blocking the transmission of rotational forces from the rotating elongate body to the guidewire. The key-engagement mechanism between the guide tube and inner liner serves as a mechanical intermediary that permits linear motion while preventing rotational coupling, thereby protecting the guidewire while allowing effective tissue removal.
2Reliability
If the inner liner is constrained to non-rotational movement, then the guidewire is protected from rotational damage, but the tissue-removing element loses rotational capability for effective tissue removal
Solution Approach 1:
The catheter system is segmented into independently movable components: the elongate body with tissue-removing element rotates freely to perform tissue removal, while the inner liner is segmented separately and constrained to translational movement only. This segmentation enables the tissue-removing element to maintain rotational capability for effective tissue removal while the guidewire within the inner liner remains protected from rotational forces.
Solution Approach 2:
The guide tube serves as a mechanical intermediary that decouples the rotational motion of the elongate body from the inner liner. The key-engagement mechanism between the guide tube and inner liner acts as a constraint intermediary, allowing the inner liner to move translationally while blocking rotational force transmission, thus protecting the guidewire while preserving the tissue-removing element's rotational functionality.
3Reliability
If a key-engagement mechanism is added to restrict inner liner movement, then rotational forces are prevented from reaching the guidewire, but the device complexity increases
Solution Approach 1:
The guide tube with integrated key-engagement mechanism serves as a compact intermediary system that efficiently restricts the inner liner to translational movement only. This intermediary design prevents rotational force transmission to the guidewire while maintaining relatively simple construction, avoiding the need for complex separate constraint mechanisms.
Solution Approach 2:
The key-engagement mechanism is merged with the guide tube structure, combining the guiding and constraint functions into a single integrated component. This merging approach reduces the number of separate parts and simplifies the overall assembly while effectively preventing rotational movement of the inner liner, thereby protecting the guidewire without significantly increasing device complexity.
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
The design effectively removes occlusive tissue while safeguarding the guidewire from damage, maintaining its integrity and reducing the risk of kinking, thereby enhancing the efficacy of procedures like PTCA and stent delivery.
Implementation Method 1
Atherectomy catheters typically employ a rotating element which is used to abrade or otherwise break up the unwanted tissue
Implementation Method 2
The guide tube is configured to extend an effective length of the guide tube to accommodate movement of the inner liner in the guide tube
Data Source
AI summary
A tissue-removing catheter for removing tissue in a body lumen includes an elongate body having an axis, and proximal and distal end portions spaced apart from one another along the axis. The elongate body is sized and shaped to be received in the body lumen. A handle is mounted to the proximal end portion of the elongate body. The handle includes a housing enclosing components operable to cause rotation of the elongate body. A tissue-removing element is mounted on the distal end portion of the elongate body. An inner liner is received within the elongate body and defines a guidewire lumen. An advancer is mounted on the handle and is movable relative to the housing. A guide tube is mounted in the handle and is coupled to the advancer such that movement of the advancer relative to the housing causes movement of the guide tube.