Extendable Medical Lead With Sealed Sheath For Patient Growth
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Solution Overview
Problem
Implantable medical devices, such as cardiac pacemakers, face tensile forces due to patient growth or movement, which can lead to stress on the implant site and potential dislodgment of electrodes, as the fixed length of medical leads does not accommodate increasing distances between the pacemaker and the electrode.
Innovation Solution
An extendable medical lead system featuring a partially coiled or gathered lead body within a sheath that can lengthen when tensile forces are applied, reducing stress on the implant site by allowing the lead to extend, while a seal at the sheath end prevents contaminant entry and minimizes tissue ingrowth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the medical lead is made with a fixed length, then the lead can be easily manufactured and implanted, but the lead cannot accommodate patient growth or movement, resulting in tensile forces that pull on the implant site and electrode
Solution Approach 1:
The medical lead incorporates a dynamic extension mechanism where the lead body can extend from a retracted position within the lead housing to an extended position outside the housing. This allows the lead to adapt its length in response to patient growth or movement, resolving the contradiction between fixed structure and adaptability requirement
Solution Approach 2:
The lead body is nested within the lead housing in a retracted state, allowing the lead to maintain a compact form factor during implantation while providing the capability to extend outward when needed. This nesting arrangement enables the lead to accommodate growth without permanently increasing the implant size
2Adaptability or versatility
If the lead body is allowed to extend freely, then the lead can accommodate growth, but body tissue or fluid may enter the lead housing through the aperture, causing contamination
Solution Approach 1:
A seal is introduced as an intermediary element between the lead body and the external environment at the aperture. This seal allows the lead body to extend and retract while preventing body tissue or fluid from entering the lead housing, thus resolving the contradiction between extendability and contamination prevention
Solution Approach 2:
The seal functions as a flexible barrier that can deform to accommodate the lead body's movement while maintaining the integrity of the housing aperture. This flexible sealing mechanism enables the lead to extend without compromising the protective barrier against contaminants
3Adaptability or versatility
If the lead body is coiled within the lead housing, then the lead can be extended when needed, but the coiled section may experience friction or resistance during extension
Solution Approach 1:
The lead body is designed to be self-actuating, where application of tensile force to the extended lead body automatically causes the coiled section to uncoil and extend without requiring external actuation mechanisms. This self-service approach minimizes additional components that could increase friction or resistance during extension
Data Source
AI summary
An extendable medical lead comprises a lead body and a sheath defining a cavity that encloses a length of the lead body. The length of the lead body enclosed within the sheath may be coiled or otherwise gathered such that when extended, the length of the enclosed section of the lead body is greater than the length of the sheath. The sheath may include a seal to help prevent contaminant entry into the cavity in order to help reduce tissue in growth around the length of the lead body disposed within the sheath. A portion of the length of the lead body enclosed within the sheath exits the cavity through an aperture defined by the seal when a tensile force is applied to the lead body.