Torque-Limiting Active Fixation Lead for Coronary Venous Pacing
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Solution Overview
Problem
Current active fixation implantable medical electrical leads face challenges in securing electrodes within the coronary venous system, particularly due to issues with over-rotation and tissue damage during implantation, which can lead to ineffective therapy delivery for left heart pacing.
Innovation Solution
The design incorporates a wire wound into a tissue-engaging helix with exposed turns and a piercing tip, secured between adjacent electrodes, along with a torque-limiting mechanism to prevent over-rotation, ensuring secure electrode placement and minimizing tissue damage. This includes an external contour or accessory sleeve to control the torque transferred from the connector terminal grip sleeve to the fixation element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wire is wound into a tissue-engaging helix with exposed turns and a piercing tip for active fixation, then the electrode can be securely anchored in the coronary venous system, but the risk of over-rotation and tissue damage increases during implantation
Solution Approach 1:
The patent applies parameter changes by modifying the mechanical properties of the lead system through a torque-limiting mechanism. This mechanism controls the torque parameter transferred from the connector terminal grip sleeve to the fixation element, preventing excessive rotation forces that could damage tissue while still allowing sufficient torque for proper helix engagement and secure anchoring.
Solution Approach 2:
The patent introduces an intermediary torque-limiting mechanism between the operator's manual torque application and the fixation element. This intermediary component regulates and limits the torque transmission, acting as a protective mediator that allows effective electrode anchoring through the helix structure while preventing harmful over-rotation and tissue damage during the implantation process.
2Reliability
If torque is applied to the connector terminal grip sleeve to engage the helix with tissue, then secure fixation is achieved, but uncontrolled torque transfer can cause over-rotation and lead displacement
Solution Approach 1:
The torque-limiting mechanism modifies the torque parameter transmission characteristics, allowing controlled torque transfer for helix engagement while preventing excessive torque that would cause over-rotation. This parameter control ensures the lead achieves stable fixation without losing positional stability or causing displacement.
3Adaptability or versatility
If the lead is designed with multiple outer insulation tubes and pre-set curvatures for flexibility and positioning, then implantation adaptability improves, but the structural complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies segmentation by dividing the lead's outer insulation into multiple separate insulation tubes, each serving specific functions. The proximal insulation tube provides structural support and torque transmission, while the distal insulation tube is pre-formed with curvature for anatomical adaptation. This segmentation allows the lead to achieve both flexibility for positioning and structural integrity for torque control.
Solution Approach 2:
The patent applies local quality by giving different sections of the lead different structural properties. The proximal portion has a stiffer construction for torque transmission, while the distal portion has pre-set curvatures for flexibility and anatomical adaptation. This local differentiation optimizes both implantation adaptability and structural performance without requiring complete redesign of the entire lead structure.
Data Source
Figure 1A
Figure 1B~1G
Figure 2A~2C
AI summary
A medical electrical lead includes a plurality of longitudinally spaced electrodes and a fixation element helix located between a proximal-most pair of adjacent electrodes of the plurality, so that a piercing tip of the helix is centered therebetween. A grip sleeve of a connector terminal of the lead may be gripped to apply a torque which is transferred to the fixation element, thereby engaging the helix thereof with tissue. The lead may include means for limiting the amount of torque that can be transferred from the connector terminal grip sleeve to the fixation element. The torque limiting means may be an external contour of the lead along a length thereof that extends between the connector terminal grip sleeve and the fixation element. The plurality of lead electrodes may further include a distal-most pair of adjacent electrodes, between which the lead extends in pre-set a curvature.