Tether Tensioning Device with Ratchet Locking
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Solution Overview
Problem
Current medical procedures face challenges in precisely and efficiently tensioning tethers during tissue repair, particularly in minimally invasive procedures where controlling tether tension remotely is difficult, and there is a need for adjustable tensioning and manipulation options like locking and cutting.
Innovation Solution
A device with a rotatable tensioning member and a handle portion that allows for adjustable tether tensioning, featuring a locking and cutting mechanism, including a compression spring and high-friction elements to control tension, and a lever system for precise control, which can be used in conjunction with a catheter for remote applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tether is tensioned too much in a tissue repair procedure, then the tissue may become damaged. Alternatively, if a tether is not sufficiently tensioned, then the underlying problem may not be fixed
Solution Approach 1:
The patent implements a ratchet mechanism that allows incremental adjustment of tether tension parameters. The ratchet teeth engage with a pawl to permit tensioning in one direction while preventing reverse motion, enabling precise control of tension levels. This mechanical parameter control system allows the operator to adjust tension in discrete steps, preventing both over-tensioning and under-tensioning of the tether.
Solution Approach 2:
The device incorporates a tensioning indicator or measurement mechanism that provides feedback to the operator about the current tether tension level. This feedback loop allows the operator to monitor tension in real-time and make adjustments accordingly, ensuring the tether is tensioned to the appropriate level without damaging the tissue or failing to resolve the underlying problem.
2Ease of operation
If tether tensioning is performed in minimally invasive catheter-based procedures with remote target sites, then the procedure is less invasive, but it becomes difficult to control the tension of the tether at the remote site
Solution Approach 1:
The patent employs a catheter as an intermediary delivery system that transports the tether tensioning device to the remote target site through the body's natural passages. The catheter provides a conduit for both delivering the tether and transmitting mechanical forces for tensioning, enabling remote control without requiring direct surgical access to the target site. This intermediary approach maintains both minimally invasive benefits and operational control.
Solution Approach 2:
The device replaces direct manual mechanical tensioning with a mechanically-assisted system incorporating a ratchet mechanism and spring-loaded components. This substitution allows for more precise and controllable tensioning at remote sites by using mechanical advantage and stored elastic energy from springs, rather than relying solely on manual manipulation through the catheter.
3Reliability
If a locking mechanism is added to prevent over-tensioning, then tissue damage is prevented, but the device complexity increases
Solution Approach 1:
The patent combines the locking function with the existing ratchet mechanism used for tensioning. The same ratchet teeth that enable incremental tensioning also serve as the locking elements that prevent over-tensioning. This merging of functions reduces device complexity compared to having separate locking and tensioning mechanisms, while still providing reliable tissue protection.
4Measurement precision
If adjustable tensioning is implemented, then precise control is achieved, but the device complexity and number of components increase
Solution Approach 1:
The patent implements a dynamic tensioning system where the ratchet mechanism allows the device to adapt to different tension requirements. The spring-loaded components provide variable force, and the ratchet teeth can engage at different positions along the tensioning range. This dynamic capability enables precise control of tether tension without requiring multiple separate devices or excessively complex mechanisms.
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
Enables precise and efficient tensioning of tethers, preventing tissue damage by allowing adjustable tension, locking, and cutting, facilitating procedures like heart valve repair even on a beating heart with improved control and safety.
Implementation Method 1
The bobbin and the tensioning wheel may be coupled by a compression spring. The compression spring may have a spring constant of at least about 1800 N/M (10 lb/inch) and/or at most about 5300 N/M (30 lb/inch). The compression spring may exert a force on the bobbin that determines the rotatability of the bobbin.
Implementation Method 2
Alternatively or additionally, the bobbin and the tensioning wheel may be coupled by a high-friction element. The high-friction element may apply a frictional force on the bobbin that determines the rotatability of the bobbin.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B~2C
AI summary
Devices, methods, and kits for tensioning tethers during a tissue modification procedure are described. In some variations, a tether coupled to anchors embedded in tissue may be tensioned to provide a cinching effect that tightens or compresses the tissue by bringing two pieces or sections of the tissue together. In certain variations, the tether may then be locked (e.g., to maintain the tension), and/or excess tether may be severed. The devices, methods, and/or kits may be used, for example, in minimally invasive procedures.