Laser-Cut Hypotube Sheath 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 tissue, which can lead to jamming and increased difficulty in removing leads due to scar tissue and fibrous tissue growth.
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 then in an opposite direction upon subsequent actuation, creating a slicing action to minimize jamming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a mechanical blade is used to cut tissue in lead extraction, then cutting capability is improved, but the blade may become jammed in tough fibrous tissue
Solution Approach 1:
The blade is designed to rotate dynamically during the cutting stroke rather than moving linearly. This rotation allows the blade to sweep through fibrous tissue more effectively and reduces the likelihood of becoming jammed, while still maintaining cutting capability through the rotational motion.
Solution Approach 2:
The cutting mechanism employs a periodic rotating motion where the blade alternates between cutting phases and retraction phases. This periodic action allows the blade to clear tissue debris and maintain effectiveness throughout the extraction process, preventing jamming while ensuring continuous cutting capability.
2Strength
If the blade extends fully to cut tough tissue, then cutting effectiveness is improved, but control precision over blade position deteriorates
Solution Approach 1:
Instead of controlling blade position solely along the extension axis, the invention introduces rotational movement as a second dimension of control. The blade's angular position and rotational speed provide additional control parameters, allowing precise positioning while maintaining full extension for effective cutting of tough tissue.
3Reliability
If the blade rotates continuously to prevent jamming, then reliability is improved, but control complexity increases
Solution Approach 1:
The invention replaces complex multi-component mechanical rotation control systems with a simpler mechanism where the blade's rotation is naturally coupled to its extension motion. This substitution reduces control complexity while maintaining continuous rotation for reliable anti-jamming performance throughout the cutting stroke.
Data Source
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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 inner 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. The inner sheath and outer sheath are constructed of laser-cut hypotubes, thereby allowing the surgical device, particularly the sheath assembly, to have a smaller profile for navigating smaller sized vasculature.