Self-Locking Winch Geometry for Valve Tether Tensioning
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Solution Overview
Problem
Dilation of the annulus of a heart valve due to ischemic heart disease prevents the valve leaflets from fully coapting, leading to regurgitation and decreased cardiac output, necessitating a mechanism to adjust and stabilize the valve.
Innovation Solution
A self-locking winch mechanism is used to apply tension to a tether anchored to the valve, utilizing a spool and mount configuration that inhibits unwinding of the tether in response to pulling forces, eliminating the need for discrete locking mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a spool is positioned to facilitate winding of the tether during forward rotation, then the spool can effectively draw the tether toward the winch, but the same position and orientation typically inhibit reverse rotation and unwinding of the tether
Solution Approach 1:
The spool is positioned asymmetrically relative to the rotation axis, with its axis offset laterally and oriented at an angle (e.g., orthogonal) to the rotation axis. This asymmetric configuration creates a geometric mechanism where forward rotation enables winding while the same geometry prevents reverse rotation, achieving self-locking without additional components.
Solution Approach 2:
Instead of using a conventional symmetric spool that requires separate locking mechanisms, the invention inverts the approach by using an asymmetric spool configuration where the geometry itself provides the locking function. The spool's offset position and angular orientation create a mechanical constraint that allows winding in one direction but blocks unwinding in the reverse direction.
2Reliability
If a discrete locking mechanism is added to prevent unwinding of the tether, then reliability is improved, but device complexity increases
Solution Approach 1:
The invention extracts and eliminates the discrete locking mechanism from the system by incorporating the locking function directly into the spool's geometry and positioning. The asymmetric spool configuration inherently prevents reverse rotation, so no separate locking components are needed, reducing device complexity while maintaining reliability.
Solution Approach 2:
The locking function is merged with the spool structure itself. The spool is designed with specific positional and orientational characteristics relative to the rotation axis that combine the winding function and the self-locking function into a single integrated component, eliminating the need for separate locking mechanisms.
3Reliability
If the spool axis is made non-coaxial with the rotation axis, then self-locking is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The spool is pre-positioned and pre-oriented during assembly with specific geometric relationships to the rotation axis (offset laterally and angled). This preliminary configuration establishes the self-locking geometry before operation, and once assembled, the mechanism maintains its locking capability through the fixed geometric relationship, reducing the need for continuous precision maintenance.
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 mechanism effectively maintains tension in the tether, stabilizing the valve and improving cardiac output by preventing unwinding, thus addressing the regurgitation issue.
Implementation Method 1
The spool can be coupled to the mount in a position and an orientation with respect to the rotation axis that facilitates the spool drawing the end portion of the tether toward the winch by winding of the tether around the spool
Implementation Method 2
the spool can be coupled to the mount in a position and an orientation with respect to the rotation axis that inhibits unwinding of the tether from the spool in response to pulling of the end portion away from the spool, by inhibiting the pulling from rotating the mount in a reverse rotational direction about the rotation axis
Data Source
AI summary
A system includes a transcatheterally-advanceable driver and an implant. The implant includes a winch, and a tether that has an end portion. The winch includes a spool, a mount, and a driver interface engageable and drivable by the driver. The mount is coupled to the driver interface such that driving of the driver interface by the driver rotates the mount about a rotation axis. The spool is coupled to the tether, and defines a spool axis that is non-coaxial with the rotation axis. The tether extends away from the winch toward the end portion. The spool is fixedly coupled to the mount such that rotation of the mount about the rotation axis draws the end portion of the tether toward the spool by winding the tether around the spool axis of the spool. Other embodiments are also described.