Blade Rotation Control for Pacemaker Lead Extraction
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Solution Overview
Problem
Current lead extraction devices face challenges in precisely controlling the extension, retraction, and rotation of blades within the vascular system, particularly in navigating tortuous paths and separating tough surrounding tissue, which can lead to difficulties in removing implanted leads due to scar tissue and vascular structure complexities.
Innovation Solution
A surgical device featuring a barrel cam cylinder in the handle assembly that imparts rotation of the blade and a separate cam mechanism in the tip of the outer sheath assembly, allowing the blade to rotate in one direction during initial extension and retraction, and alternating directions with subsequent actuations to create a slicing action, minimizing the risk of blade jamming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a blade is extended to cut scar tissue, then the ability to separate tissue from the lead is improved, but the risk of blade jamming in tortuous vascular paths increases
Solution Approach 1:
The blade is designed to rotate dynamically during extension and retraction rather than moving linearly. This rotation allows the blade to navigate tortuous vascular paths more effectively and prevents it from becoming jammed in scar tissue, while still maintaining the ability to cut through the tissue during the extraction process.
Solution Approach 2:
The blade performs periodic extension and retraction movements with alternating rotation directions. During initial extension, the blade rotates in one direction to cut scar tissue; during retraction, it rotates in the opposite direction to clear debris and prevent jamming. This periodic action with alternating directions enhances both cutting efficiency and reliability.
2Productivity
If the blade rotates in one direction during extension, then the cutting action on scar tissue is improved, but the blade may become jammed during retraction
Solution Approach 1:
The system implements periodic action with alternating rotation directions. The blade rotates in one direction during extension to maximize cutting efficiency, then rotates in the opposite direction during retraction to prevent jamming and ensure smooth operation. This alternating periodic rotation resolves the contradiction between cutting efficiency and retraction smoothness.
Solution Approach 2:
The rotation direction is inverted between extension and retraction phases. Instead of maintaining the same rotation direction, the blade reverses its rotation during retraction, which prevents it from becoming jammed in the scar tissue it just cut through, thereby improving ease of operation without sacrificing cutting efficiency.
3Device complexity
If a simple extension mechanism is used, then the device complexity is reduced, but the ability to control blade rotation and prevent jamming is insufficient
Solution Approach 1:
The extension and rotation functions are merged into a single integrated mechanism. The cam cylinder simultaneously controls both the extension/retraction motion and the rotation of the blade through its cam profile, eliminating the need for separate control mechanisms. This merging maintains relative simplicity while achieving precise control over blade motion and rotation, thereby improving reliability without significantly increasing 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
Enables precise and efficient removal of implanted leads by effectively cutting and separating scar tissue from the lead, reducing the risk of complications and improving the safety and success rate of lead extraction procedures.
Implementation Method 1
a barrel cam cylinder comprising a barrel cam cylinder slot for receipt and cooperation with the trigger pin
Implementation Method 2
creating a slicing action, minimizing the risk of blade jamming
Data Source
AI summary
Methods and devices for separating an implanted object, such as a pacemaker lead, from tissue surrounding such object in a patient's vasculature system. Specifically, the surgical device includes a handle, an elongate sheath and a circular cutting blade that extends from the distal end of the sheath upon actuating the handle. The circular cutting blade is configured to engage the tissue surrounding an implanted lead and cut such tissue in a coring fashion as the surgical device translates along the length of the lead, thereby allowing the lead, as well as any tissue remaining attached to the lead, to enter the device's elongate shaft. The surgical device has a barrel cam cylinder in the handle assembly that imparts rotation of the blade and a separate cam mechanism in the tip of outer sheath assembly that imparts and controls the extension and retraction of the blade. The barrel cam cylinder and cam mechanism cooperate to cause the blade to rotate in a first direction and extend from and retract in the outer sheath due to a first actuation of the handle and to rotate in a second direction and extend and retract in the outer sheath due to a second actuation of the handle.