Defibrillation Coil Filling Method for Isodiametry
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Solution Overview
Problem
Existing defibrillation coils in implantable cardioverter/defibrillators face issues with fibrotic tissue growth due to immune reactions, leading to decreased electrical conductivity and difficulty in removal, as well as manufacturing drawbacks such as irregular filling and diameter changes, which affect the coil's effectiveness and implantation.
Innovation Solution
A method involving a polyurethane tube insertion into the conductive coil, followed by thermal energy application and pressure to deform the tube wall, filling the spaces between the coil turns without creating cavities, ensuring mechanical stability and maintaining isodiametry, thereby minimizing fibrotic tissue growth and improving coil performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the defibrillation coil is left unfilled between turns, then the manufacturing process is simple, but fibrotic tissue grows in the cavities causing decreased electrical conductivity and implantation complications
Solution Approach 1:
The patent applies filling material to the spaces between coil turns during the manufacturing process before implantation. This preliminary action prevents fibrotic tissue growth cavities from forming, ensuring maintained electrical conductivity and reliable therapy delivery throughout the device's operational life.
Solution Approach 2:
The patent converts the harmful effect of empty spaces between turns (which promote fibrotic tissue growth) into a beneficial structure by filling these spaces with insulating material. This transforms the potential harm into a controlled feature that maintains coil geometry and prevents tissue encapsulation while preserving electrical performance.
2Reliability
If filling material is applied to the coil turns, then fibrotic tissue growth is minimized, but the manufacturing process becomes complex and irregular
Solution Approach 1:
The patent specifies precise parameters for the filling material including electrical resistivity greater than 10^9 ohm·cm, porosity between 0-50%, and density between 0.5-2.0 g/cm³. These controlled parameter changes ensure consistent manufacturing results that prevent fibrotic tissue growth while maintaining isodiametric coil geometry and reliable electrical performance.
Solution Approach 2:
The patent applies filling material specifically to the spaces between coil turns where fibrotic tissue growth occurs, while leaving the functional coil surfaces exposed to tissue for effective therapy delivery. This localized application of different material properties solves the contradiction by addressing only the problematic areas without compromising overall coil functionality.
3Ease of manufacture
If the coil diameter varies along its length, then the coil can be manufactured more easily, but implantation and removal become difficult due to loss of isodiametry
Solution Approach 1:
The patent applies filling material during manufacturing to maintain isodiametric geometry of the coil before implantation. This preliminary structural reinforcement ensures uniform diameter throughout the coil length, facilitating smooth implantation through venous access and simplifying subsequent removal procedures without tissue damage.
Solution Approach 2:
The patent combines the conductive coil material with insulating filling material to create a composite structure that maintains isodiametric geometry. This composite construction provides mechanical stability and uniform diameter along the coil length while preserving electrical functionality, solving the contradiction between manufacturing ease and operational ease.
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
The method results in a defibrillation coil with no cavities between turns, reducing fibrotic tissue formation, maintaining mechanical stability, and ensuring optimal surface exposure for effective therapy delivery, while being easy to manufacture and implant.
Implementation Method 1
a thermal energy input step to soften the tube
Implementation Method 2
a step of applying pressure on the assembly formed by the elongate conductive coil and the tube to deform the tube wall by insertion of the tube wall between the turns of the elongate conductive coil
Data Source
Figure 1~2
Figure 3~4
Figure 5~9a
AI summary
The disclosure relates to a method of manufacturing an implantable defibrillation coil for a lead of an active implantable medical device, the defibrillating coil includes at least one elongate conductive coil which includes a plurality of non-contiguous turns. The method includes inserting a tube of polymeric material within the elongated conductive coil, supplying thermal energy to soften the tube, applying pressure on the assembly formed by the elongate conductive coil and causing the tube to deform the tube wall by insertion of the tube wall between the turns of the elongate conductive coil.