Surgical Sheath with Non-Uniform Wall Thickness for Lead Extraction
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Solution Overview
Problem
Current lead extraction devices face challenges in safely removing implanted cardiac pacing system leads due to scar tissue formation and attachment to vascular walls, particularly in tortuous vascular environments, requiring precise control to avoid inadvertent contact with the blade during extension and rotation.
Innovation Solution
A surgical device with a non-uniform outer sheath having increased wall thickness at specific portions to shield the vasculature from the blade, combined with a guide structure like a deflector and a cutting device such as a blade or laser ablation system, facilitates safe extraction by maintaining a greater distance between the blade and the vasculature and guiding the lead into a lumen for removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a blade is extended and rotated to cut scar tissue during lead extraction, then the cutting effectiveness is improved, but the risk of inadvertent contact with the vasculature increases
Solution Approach 1:
The patent introduces an intermediary protective structure (outer sheath with increased wall thickness) between the blade and the vasculature. This mediator shields the vulnerable vascular tissue from direct contact with the rotating blade while allowing the blade to effectively cut the scar tissue encasing the lead, thus resolving the contradiction between cutting effectiveness and vascular safety
Solution Approach 2:
The patent implements prior cushioning by pre-positioning the protective outer sheath with increased wall thickness at specific portions before blade extension. This pre-established protective barrier cushions the vasculature against potential blade contact during the cutting operation, allowing aggressive cutting action without increasing vascular risk
2Force
If mechanical traction is used to extract the lead, then the extraction force is applied directly, but the difficulty of removal increases due to scar tissue encasement
Solution Approach 1:
The patent applies preliminary action by extending the rotating blade to cut through the scar tissue encasement before attempting mechanical traction extraction. This pre-cutting action removes the barriers that would otherwise resist extraction force, transforming the extraction process from high-resistance direct pulling to facilitated removal through the created opening
Solution Approach 2:
The patent segments the extraction process into two distinct phases: first, cutting the scar tissue encasement with the rotating blade to create an opening, and second, applying mechanical traction through the created opening. This segmentation allows each force application to be optimized for its specific function, improving overall extraction reliability
3Object-affected harmful factors
If the outer sheath wall thickness is increased at specific portions to protect vasculature, then the safety is improved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by increasing the wall thickness of the outer sheath only at specific portions where vascular protection is most needed, rather than uniformly throughout the entire sheath. This localized thickening provides targeted protection while minimizing the overall structural complexity and material usage compared to a uniformly thick-walled sheath
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 device effectively protects the vasculature from blade contact and enables precise control during lead extraction, reducing the risk of vascular damage and improving the safety and success of lead removal procedures.
Implementation Method 1
a cutting device such as a blade or laser ablation system
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 tissue separating device includes a handle, an elongate sheath and a circular cutting blade that may extend from the distal end of the sheath upon actuating the handle. The elongate sheath, particularly its distal end, includes a non-uniform wall thickness having one or more thicker portions in the outer sheath, particularly the outer cam member, and/or one or more thicker portions in an inner member disposed radially inward of the blade. Having an increased wall thickness for a portion of either or both of the outer cam member and circular inner member assists in shielding the vasculature from the blade during extension and guides the lead away from that portion of the inner cam member and towards the center of the lumen, thereby decreasing the likelihood that the cutting surface will cut the lead upon lead entry or upon contact the tissue upon blade extension.