Implantable Lead Strain Relief Deflection Wall
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Solution Overview
Problem
Implantable medical leads face mechanical stress during implantation and use, leading to potential breakage of conductive wires and electrical connections, especially for wires with diameters less than 200 micrometers, due to inadequate strain relief mechanisms that may come into contact with heart tissue, increasing contamination risks.
Innovation Solution
A strain relief device is integrated into the implantable lead, featuring a deflection wall misaligned with the longitudinal axis, which deflects conductive wires non-radially, reducing axial tension and preventing breakage by blocking the wires against the deflection wall, thus enhancing the mechanical strength and longevity of the electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a flexible tube strain relief device is placed around the implantable lead body, then the tensile strength of the conductive wire is improved, but the risk of contamination increases due to direct contact with heart tissue
Solution Approach 1:
The strain relief device is extracted from the distal end of the lead and repositioned to the proximal end, inside the housing of the implantable medical device. This extraction from the tissue-contacting region eliminates the contamination risk while preserving the strain relief function. The device is now housed within the device body, completely isolated from heart tissue.
Solution Approach 2:
The housing of the implantable medical device serves as an intermediary barrier between the strain relief device and the heart tissue. By placing the strain relief device inside the housing, the housing acts as a mediator that prevents direct contact between the strain relief device and the biological environment, thus eliminating contamination risk while maintaining mechanical protection.
2Strength
If radially extending elements are used in the strain relief device, then the distribution of stress is improved, but the space occupied and device complexity increase
Solution Approach 1:
The strain relief device employs an asymmetric design with a deflection wall that creates a non-radial deflection path for the conductive wire. Instead of symmetric radial elements, the deflection wall is positioned to create an asymmetric stress distribution that effectively redirects tension forces away from the weld connection, achieving stress management with simpler geometry.
Solution Approach 2:
The strain relief mechanism transitions from a radial stress distribution (multiple elements extending outward) to a dimensional approach where the deflection wall creates a three-dimensional deflection path. The conductive wire is deflected along a curved trajectory rather than being distributed radially, achieving stress relief through spatial redirection rather than radial multiplication of elements.
3Strength
If the conductive wire is deflected radially around the longitudinal axis, then the strain relief is achieved, but the length of the device required increases
Solution Approach 1:
The deflection wall creates a curved deflection path for the conductive wire, utilizing spherical or cylindrical geometry to redirect the wire. This curvature allows the wire to follow a compact arc rather than a long radial path, achieving effective strain relief in a shorter device length. The rounded geometry of the deflection wall optimizes the stress redistribution along the curved path.
Data Source
AI summary
The present invention relates to an implantable lead comprising at least one conductive wire and a connector. The connector is configured to be connected to an implantable medical device, such as a cardiac stimulation, a defibrillation or/and a neuromodulation device, and further comprising a strain relief device extending longitudinally along an axis from one end of the connector and essentially parallel to the longitudinal axis of the connector. The conductive wire is deflected by a deflection wall of the strain relief device such that the deflection wall of the strain relief device blocks the conductive wire against the deflection wall when the conductive wire is stressed in tension, and the deflection wall extends along an axis which is misaligned with the longitudinal axis of the strain relief device.