Active Fixation Lead With Low-Friction Conductive Spring Contact
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Solution Overview
Problem
Existing implantable pacing and defibrillation leads suffer from electrical chatter noise due to intermittent contact between the helix electrode and metallic housing, leading to inappropriate therapy delivery, and mechanical friction affecting smooth deployment, while also having issues with fluid ingress and reduced long-term reliability due to rigid and flexible portions.
Innovation Solution
The lead design incorporates an electrically conductive compression spring providing continuous electrical contact and reduced friction, a tubular body with radial openings, and a sealing mechanism to prevent fluid ingress, along with a compacted rigid portion structure using superimposed electrodes and an insulating sheath to enhance stability and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compression spring is positioned around the conductive driver to generate electrical contact, then electrical chatter noise is reduced, but mechanical friction increases causing jerky driver movement
Solution Approach 1:
The patent introduces an electrically conductive lubricious coating as an intermediary layer between the compression spring and the conductive driver shaft. This coating mediates the interaction by providing electrical conductivity for contact while reducing mechanical friction, thus resolving the contradiction between electrical contact stability and driver movement smoothness
Solution Approach 2:
The patent changes the surface properties of the conductive driver shaft by applying a lubricious coating, which modifies the friction parameter between the spring and driver. This parameter change allows the system to maintain electrical contact while reducing mechanical resistance, enabling smooth driver deployment
2Ease of operation
If a short flexible portion is arranged between two rigid portions of the lead, then lead implantation is facilitated, but long-term reliability is reduced due to mechanical stress concentration
Solution Approach 1:
The patent applies a flexible polymer coating on the conductive driver shaft, which acts as a flexible shell that can accommodate mechanical stress. This flexible layer protects the underlying metallic structure from stress concentration while maintaining the necessary flexibility for implantation, thus resolving the contradiction between ease of implantation and long-term reliability
3Strength
If the distal housing portion is made rigid to provide structural support, then sealing properties are improved, but fluid ingress prevention is reduced
Solution Approach 1:
The patent employs a flexible polymer coating on the conductive driver shaft that extends into the distal housing portion. This flexible shell creates a barrier against fluid ingress while allowing the rigid housing to maintain its structural support function, thus resolving the contradiction between structural strength and fluid sealing
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
This design reduces chatter noise, improves mechanical stability, enhances sealing properties, and increases long-term reliability by minimizing friction and fluid ingress, facilitating easier assembly and placement.
Implementation Method 1
an electrically conductive compression spring... providing continuous electrical contact
Implementation Method 2
compression spring... forced by its restoring force against the conductive driver shaft
Implementation Method 3
reduces friction... minimizing friction and fluid ingress
Implementation Method 4
a sealing mechanism to prevent fluid ingress... enhances sealing properties
Data Source
Figure 1~2
Figure 3A~3D
Figure 3E~3G
AI summary
The present invention relates to an implantable pacing and/or defibrillation lead (10, 100, 200) wherein the electrical connection between active fixation electrode (22, 26, 126) and a distal housing portion (122, 222) of the lead (10, 100. 200) is realized by means of an electrically conductive compression spring (176, 276) is at least partially radially arranged around a tubular body (138, 238) of a guiding member (35, 136, 236) and a radial opening (158, 258) of the guiding member (136, 236), such that the electrically conductive compression spring (176, 126) is forced by its restoring force against a conductive driver shaft (120, 220) mechanically and electrically connected to the active fixation electrode (126, 226).