Coaxial Tether Cutter for Precise Single-Pass Shearing
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Solution Overview
Problem
Existing methods for cutting medical tethers at a target site are unreliable, often fail to fully cut the tether, or prematurely cut it, and may result in loose pieces due to multiple cuts.
Innovation Solution
A tether-cutting device comprising a catheter, inner shaft, and cutting blade, where the blade is coaxially arranged within the catheter lumen, allowing simultaneous rotation and translation to apply a shearing force for reliable cutting, with a mechanism to protect the tether until ready to cut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current cutting devices and methods are used on strong surgical tethers, then the tether can be cut, but the cutting is unreliable and may fail to fully cut the tether or cut it prematurely
Solution Approach 1:
The cutting blade is designed to be rotatable and longitudinally translatable, allowing it to dynamically adjust its position and orientation during the cutting process. This dynamic capability enables the blade to reliably cut through strong tethers by applying cutting force from multiple directions and positions, resolving the contradiction between cutting reliability and tether strength
Solution Approach 2:
The cutting device is segmented into distinct functional components: a rotatable blade, a longitudinally movable blade, and a positioning mechanism. This segmentation allows each component to independently perform its specific function (cutting, applying force, positioning), thereby achieving reliable cutting of strong tethers through coordinated action of specialized components
2Measurement precision
If the cutting blade is positioned at the target site, then the tether can be cut at the correct location, but the tether may be prematurely cut before the device is properly positioned
Solution Approach 1:
The device incorporates a positioning mechanism that must be properly engaged at the target site before the cutting blade becomes operational. The blade is initially held in a retracted or protected position and only becomes capable of cutting after the device is correctly positioned, preventing premature cutting while enabling precise cutting at the intended location
Solution Approach 2:
A positioning mechanism acts as an intermediary between the cutting blade and the tether. This intermediary component ensures that the blade only contacts and cuts the tether after proper positioning has been achieved, thereby preventing premature cutting while maintaining cut location precision
3Productivity
If multiple cutting points are used on the tether, then the tether can be fully severed, but loose pieces of tether are formed requiring additional retrieval steps
Solution Approach 1:
The cutting blade is designed to move continuously along the tether in a single sweeping motion, applying cutting force progressively along the tether's length. This continuous cutting action severs the tether in one operation without creating loose intermediate pieces, thereby achieving complete cutting while simplifying the retrieval process by eliminating the need to retrieve multiple loose tether segments
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
Facilitates consistent and complete cutting of tethers at the target site, preventing premature cuts and loose pieces by ensuring a single, effective cut.
Implementation Method 1
allowing simultaneous rotation and translation to apply a shearing force for reliable cutting
Data Source
AI summary
Devices and methods for cutting a tether are described herein. Devices described herein generally comprise a proximal handle, a catheter, and an inner shaft and a cutting blade disposed within the lumen of the catheter, where the cutting blade is movably disposed over the inner shaft. The proximal handle comprises an actuation mechanism to control the movement of the components of the device. Methods described herein generally comprise advancing a tether-cutting device over a tether, loading the tether through the catheter and inner shaft, applying tension to the tether, and rotating and distally translating a cutting blade in order to cut the tether.