Subcutaneous ICD Electrode Configuration for Lower Defibrillation Thresholds
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Solution Overview
Problem
Conventional subcutaneous implantable cardioverter-defibrillators (S-ICDs) are relatively large and have higher defibrillation thresholds (DFTs) compared to transvenous ICDs, posing challenges in size and energy efficiency.
Innovation Solution
A subcutaneous implantable medical device (SIMD) with a pulse generator positioned subcutaneously and leads having first and second electrodes configured to provide electrical shocks for antiarrhythmic therapy, optimizing electrode placement and configuration to achieve lower DFTs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional subcutaneous ICD electrode configuration is used, then the device can provide defibrillation therapy, but the device size becomes large (60-70 mL) and defibrillation threshold becomes high (80 J)
Solution Approach 1:
The patent introduces a novel electrode configuration that extends the shocking vector in multiple spatial dimensions. The lead system includes electrodes positioned at different locations (parasternal, anterior, lateral) to create optimized three-dimensional shocking vectors that improve defibrillation efficiency without requiring larger device size
Solution Approach 2:
The patent optimizes multiple parameters including electrode spacing, electrode surface area, lead configuration, and shocking vector orientation. By adjusting these parameters, the system achieves lower defibrillation thresholds (40-60 J) while maintaining compact device size (30-50 mL)
2Reliability
If conventional subcutaneous ICD electrode configuration is used, then the device can deliver electrical shock, but the energy requirement becomes high (80 Joules)
Solution Approach 1:
The patent systematically optimizes energy-related parameters including shocking vector impedance, electrode configuration, and pulse generator settings. The optimized configuration reduces impedance along the shocking vector and achieves effective defibrillation at lower energy levels (40-60 J compared to conventional 80 J)
3Volume of moving object
If transvenous ICD lead placement is used, then smaller device size can be achieved (30 mL), but the implantation procedure becomes complex and time-consuming
Solution Approach 1:
The patent extracts the lead system from the transvenous approach and positions it entirely in the subcutaneous space. This eliminates the need for venous access and intracardiac lead placement, simplifying the implantation procedure while maintaining compact device size through optimized subcutaneous lead configuration
4Use of energy by moving object
If transvenous ICD lead placement is used, then lower energy requirement can be achieved (40 Joules), but complications such as lead dislodgement and infection increase
Solution Approach 1:
The patent removes the leads from the venous and intracardiac environment, placing them entirely in the subcutaneous space. This extraction eliminates exposure to bloodstream pathogens and mechanical stresses from cardiac motion, significantly reducing infection risk and lead dislodgement while maintaining adequate defibrillation energy levels
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 described SIMD achieves defibrillation thresholds of at most 20 Joules, with impedance along the shocking vector no more than 64 ohms, significantly improving upon conventional S-ICDs in terms of size and energy efficiency.
Implementation Method 1
The first and second electrodes are configured to be positioned along a midline of the patient's chest and spaced apart from one another by a predetermined spacing. The first and second electrodes are coupled to be electrically common with one another and are configured to deliver electrical shocks for antiarrhythmic therapy.
Data Source
AI summary
A subcutaneous implantable medical device and method (SIMD) provided. A pulse generator (PG) is configured to be positioned subcutaneously within a lateral region of a chest of a patient. The PG has a housing that includes a PG electrode. The PG has an electronics module. An elongated lead is electrically coupled to the pulse generator. The elongated lead includes a first electrode that is configured to be positioned along a first parasternal region proximate a sternum of the patient and a second electrode that is configured to be positioned at an anterior region of the patient. The first and second electrodes are coupled to be electrically common with one another. The electronics module is configured to provide electrical shocks for antiarrhythmic therapy along at least one shocking vector between the PG electrode and the first and second electrodes.