Catheter Locking Unit Torque Resistance
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Solution Overview
Problem
Prior art introducer devices face issues with relative rotation between the pusher rod and sheath during implantation, leading to incorrect placement and torque-related problems due to inadequate locking mechanisms.
Innovation Solution
A locking unit with deformable engagement members, including a nut with a frusto-conical biasing surface and radial locking members, provides a strong and stable connection between the sheath and pusher rod, preventing longitudinal and rotational movement, and can be easily released by twisting action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a locking clip is used to connect the pusher rod and sheath, then longitudinal movement is limited, but rotation and axial movement of the proximal end are still permitted
Solution Approach 1:
The locking unit is divided into multiple functional segments: a locking body with longitudinal engagement features, radial locking members for rotational constraint, and a separate actuation mechanism. This segmentation allows each component to specialize in preventing specific types of movement, collectively achieving complete rotational and longitudinal stability.
Solution Approach 2:
The locking mechanism transitions from simple longitudinal clipping to multi-dimensional constraint by adding radial locking members that extend perpendicular to the longitudinal axis. These radial members engage with corresponding features on the pusher rod and sheath, adding rotational constraint in a new dimensional plane.
2Reliability
If a strong locking connection is provided between the pusher rod and sheath, then rotation is prevented, but the locking unit becomes difficult to release
Solution Approach 1:
A cam-shaped actuation surface acts as an intermediary between the user's rotational input and the locking members. This cam surface converts a simple rotational motion into the complex coordinated movements required to disengage both the longitudinal and radial locking features simultaneously, making release as easy as applying rotation.
Solution Approach 2:
The locking mechanism uses dynamic geometric relationships where the cam surface profile is designed to progressively disengage locking members during rotation. The changing geometry of the cam surface during actuation provides mechanical advantage that varies through the rotation cycle, reducing the force required at critical disengagement points.
3Ease of operation
If the sheath is made flexible to pass through lumens, then it can be easily introduced, but it cannot withstand rotational torque during implant placement
Solution Approach 1:
The locking unit merges the flexible sheath and rigid pusher rod into a unified torque-resistant assembly through positive mechanical engagement. The engagement features create a rigid connection that allows the combination to withstand rotational torques during implant placement while the sheath remains flexible for navigation.
Solution Approach 2:
The system effectively creates a composite structure combining the flexible polymer sheath with the rigid metallic or polymer pusher rod through the locking mechanism. This composite assembly exhibits both the flexibility of the sheath for navigation and the torque resistance of the rigid components during implantation.
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 locking unit ensures accurate rotation and placement of implants by reducing relative torque between the sheath and pusher rod, facilitating precise deployment and easy removal during medical procedures.
Implementation Method 1
a biasing member is provided with at least one biasing surface operable to bias the flexible members towards a reduced annular form and thereby into a locking position
Implementation Method 2
The locking unit ensures accurate rotation and placement of implants by reducing relative torque between the sheath and pusher rod
Implementation Method 3
there is also provided a radial locking member arranged to prevent rotational movement of the sheath relative to the insert member
Data Source
Figure 1
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Figure 3~4
AI summary
There is disclosed a locking unit (100) for locking a pusher (128) to a sheath assembly (164). The locking unit (100) includes a longitudinal locking portion (102) and a radial locking portion (104). The longitudinal locking portion (102) includes a plurality of cantilevered fingers (110) provided with longitudinally extending teeth (112) on internal surfaces thereof. A nut (108) can be tightened in order to bias the cantilevered arms (110) towards a pusher (128) such that the teeth (112) indent the outer surface of the pusher (128) to produce a strong and stable locking connection thereto. The radial locking section (104) latches onto the assembly integral with the sheath (164) so as to provide a radial locking action as well as a longitudinal locking action. The locking unit (100) provides a strong and reliable locking action between the pusher (128) and the sheath assembly (164) and can be easily removed by a clinician or surgeon during the deployment process.