Implantable Medical Lead With Polymeric Stylet Tube and Softer Distal Backfill
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Solution Overview
Problem
Conventional implantable medical leads face challenges in steerability and pushability due to flexibility, which leads to kinking and whipping actions during insertion, and the inclusion of metal coils increases costs without adequate torsional stiffness.
Innovation Solution
The implantable medical lead features a polymeric tube with a higher durometer rating for increased torsional stiffness and a softer backfill material at the distal end to reduce whipping action, along with a polymeric stylet tube and backfill materials to enhance steerability and pushability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal coil is included within the polyurethane tube to prevent kinking, then the lead gains torsional stiffness, but the outside diameter increases and manufacturing cost increases
Solution Approach 1:
The patent removes the metal coil from the lead construction entirely, extracting the problematic element that caused increased diameter and cost. Instead, a polymeric tube with enhanced mechanical properties is used to provide the necessary structural support without the drawbacks of metal coils.
Solution Approach 2:
The patent replaces expensive metal coils with a cost-effective polymeric tube solution. The polymeric material provides sufficient durability for the application while being significantly cheaper to manufacture and process than metal alternatives.
2Adaptability or versatility
If the lead is made flexible to follow the desired pathway, then the lead can navigate complex anatomy, but the lead becomes susceptible to kinking during insertion
Solution Approach 1:
The patent applies different mechanical properties to different regions of the lead. The polymeric tube has higher durometer rating in specific segments to provide kink resistance where needed, while maintaining overall flexibility for pathway navigation. This localized differentiation of material properties resolves the contradiction between flexibility and kink resistance.
3Ease of operation
If axial rotation is applied to the stylet to change steering direction, then the distal end can be redirected, but whipping action occurs that causes loss of directional control
Solution Approach 1:
The patent uses a softer backfill material in the distal end of the lead to cushion and dampen the whipping action that occurs during stylet rotation. This softer material absorbs the mechanical energy that would otherwise cause directional instability, providing beforehand protection against loss of control during steering maneuvers.
4Ease of operation
If a stylet with bent end is used to steer the lead, then directional control is achieved, but the conventional lead structure does not adequately respond to stylet manipulation
Solution Approach 1:
The patent changes the mechanical parameters of the lead structure, specifically using a polymeric tube with higher durometer rating and softer backfill material. These parameter changes make the lead more responsive to stylet manipulation while maintaining adequate structural support, directly addressing the lack of responsiveness in conventional leads.
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 improves the ability to control and insert the lead effectively, reducing kinking and whipping actions while maintaining cost-effectiveness by using polymeric materials instead of metal coils, thus enhancing the implantability of medical leads.
Implementation Method 1
a polymeric tube with a higher durometer rating, and thus a greater torsional stiffness, than the outer lead body to provide the stylet lumen and increase the pushability of the lead
Implementation Method 2
a backfill material in the distal end that is softer than the backfill material of conventional leads to reduce the whipping action that occurs at the distal end during rotation of the bent distal tip of the stylet
Data Source
AI summary
Implantable medical leads include at least one of a polymeric stylet tube and/or a distal backfill material that is softer than is conventional at least in the area where a stylet bend will cause a distal bend in the lead. The polymeric stylet tube provides for improved torsional and column stiffness during insertion while the softer distal backfill material reduces a whipping action to increase the steerability and control of the lead during insertion. The softer backfill material may be provided alone or in combination with a harder distal backfill material. The softer backfill material may be provided as an insert that is encapsulated by the harder distal back fill material or may be provided as a backfill material that exists in a position adjacent to the harder backfill material.