Lead Implantation Tool Ratchet Mechanism for Helix Fixation
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Solution Overview
Problem
Existing methods for fixing an active fixation helix into heart tissue are inadequate, as insufficient rotation leads to poor fixation, while excessive rotation can damage the weld joints or perforate the heart wall, and there is a need for a device that facilitates proper helix fixation.
Innovation Solution
A lead implantation tool that converts linear movement into rotational movement of the contact pin, allowing for precise control of the helix tip extension and retraction, reducing the risk of over-rotation and damage, and includes a mechanism for displacing a stylet to locate and fix the lead at the implantation site.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact pin is rotated manually to extend the helix for fixation, then the helix can be anchored into heart tissue, but it is difficult to control the number of rotations precisely, leading to either insufficient fixation or excessive rotation that damages weld joints or perforates the heart wall
Solution Approach 1:
A ratchet mechanism is introduced as an intermediary device between the manual operator and the contact pin rotation. The ratchet allows controlled incremental rotation of the contact pin while preventing reverse rotation, enabling precise control over the number of rotations (typically 5-15 rotations) to achieve proper helix fixation without over-rotation damage or insufficient fixation
Solution Approach 2:
The system changes the rotational parameter control by using a ratchet mechanism that permits rotation only in discrete incremental steps. This transforms the continuous rotation control problem into a discrete step control system, where each ratchet engagement allows a controlled amount of rotation, ensuring the contact pin rotates the precise number of times needed for reliable helix fixation
2Reliability
If a clip-on tool or implant tool is used to rotate the contact pin, then the helix fixation can be achieved, but the tool complexity increases and the procedure requires multiple steps
Solution Approach 1:
The ratchet mechanism is integrated directly into the lead delivery catheter system, merging the rotation control function with the existing delivery tool. This combination eliminates the need for separate complex implantation tools while maintaining reliable helix fixation, as the ratchet is built into the catheter structure itself and works in conjunction with the existing contact pin and helix assembly
3Reliability
If the contact pin rotates excessively to ensure adequate helix fixation, then the helix anchors securely into tissue, but the weld joints may be damaged or the heart wall may be perforated
Solution Approach 1:
The ratchet mechanism provides mechanical feedback by allowing rotation only in controlled incremental steps and preventing reverse rotation. This feedback system ensures that the contact pin rotates exactly the number of times needed for secure helix anchoring (typically 5-15 rotations), stopping automatically after the predetermined number of engagements, thereby preventing excessive rotation that could damage weld joints or perforate the heart wall
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 tool ensures proper fixation of the helix to heart tissue by allowing a predetermined number of rotations, reducing the risk of perforation or inadequate fixation, and simplifies the implantation process by integrating the functions of lead location and fixation into a single device.
Implementation Method 1
The worm gear may be operably coupled to the handle and the first digit engagable member, wherein linear displacement of the first digit engagable member may result in rotational displacement of the worm gear
Data Source
AI summary
A lead implantation tool is used for the implantation of active fixation medical leads. The tool may be configured to operably couple to a lead connector end of an implantable cardiac electrotherapy lead including an active fixation helix tip and wherein the lead connector end includes a contact pin proximally extending from the lead connector end. The tool may include a feature configured to couple to the contact pin and a first mechanism configured to convert linear movement into rotational movement of the contact pin relative to the lead connector end. The tool may further include a second mechanism that causes a stylet extending through the tool and into the contact pin to at least one of distally and proximally displace within the contact pin.