Bi-Directional Steerable Catheter With Ratchet-Based Auto-Lock
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Solution Overview
Problem
There is an ongoing need for alternative medical devices and methods for manufacturing and using medical devices, particularly for steering catheters and elongate tubular shafts, to enhance navigation through tortuous anatomy and improve delivery and access to body lumens and treatment sites.
Innovation Solution
A bi-directional steerable catheter with an auto lock feature, featuring a handle and an elongate shaft, includes an axial translation mechanism with a rotatable knob that engages a threaded member to bend the distal portion of the sheath in two directions, and incorporates a pulley wheel and tensioning member to maintain tension on steering wires, ensuring precise control and retention of the bent position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rotatable knob is used to control the threaded member for steering the catheter, then the ease of operation is improved, but the reliability deteriorates because the knob may unintentionally rotate or slip under continuous manipulation
Solution Approach 1:
The system uses the user's own manipulation of the catheter to automatically engage the ratchet mechanism. When the user manipulates the catheter and the threaded member rotates in the locking direction, the ratchet teeth automatically engage with the corresponding slots, providing self-locking without requiring a separate locking action or additional components.
Solution Approach 2:
The ratchet mechanism provides dynamic locking behavior where the threaded member can rotate freely in the unlocking direction but is automatically locked when rotating in the locking direction. This dynamic characteristic allows the system to adapt to user manipulation while maintaining stability when needed.
2Ease of operation
If the threaded member is made smooth to reduce friction during rotation, then the ease of operation is improved, but the reliability deteriorates because the threaded member may slip or rotate unintentionally
Solution Approach 1:
The ratchet mechanism automatically engages to prevent slipping during threaded member rotation. The ratchet teeth and slots work together to provide self-locking, eliminating the need for additional friction-based retention mechanisms while maintaining smooth operation.
Solution Approach 2:
The ratchet mechanism acts as an intermediary between the threaded member and the handle. It mediates the rotational motion by allowing free rotation in one direction while automatically preventing reverse motion, thus controlling the threaded member's position without requiring high friction surfaces.
3Reliability
If the ratchet mechanism is added to prevent unwanted rotation of the threaded member, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The ratchet mechanism is merged with the existing handle and threaded member assembly. The ratchet teeth are integrated into the handle structure while the slots are formed in the threaded member, combining multiple functions (steering control, locking, and structural support) into a unified mechanism rather than adding separate components.
Solution Approach 2:
The ratchet mechanism provides automatic locking through the interaction between the ratchet teeth and slots during normal operation. This self-locking feature eliminates the need for additional locking components, buttons, or complex control systems, thereby limiting the increase in 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 bi-directional steerable catheter provides precise control and maintains the bent position of the distal portion, facilitating navigation through complex anatomies and enhancing the delivery of medical implants and treatment procedures.
Implementation Method 1
a threaded member (122) slidably disposed within the handle (110) and a rotatable knob (124) disposed about the handle recess (154) and configured to engage the threaded member (122) such that rotation of the rotatable knob (124) relative to the handle (110) causes axial translation of the threaded member (122) within the handle (110)
Implementation Method 2
A first steering wire (130) extends through the elongate sheath (140) from the handle (110) to a distal pull ring (150) and is configured to engage with the threaded member (122) to bend a distal portion (144) of the elongate sheath (140) in a first direction
Data Source
AI summary
A bi-directional steerable catheter includes a handle and a steerable elongate sheath extending distally from the handle. A rotatable knob may be actuated to cause a distal portion of the steerable elongate sheath to bend in a first direction or a second direction. An auto lock feature holds the rotatable knob at its rotational position when a user releases the rotatable knob. The auto lock feature may include particular geometries, materials and surface roughness parameters.