Implantable Pulse Generator Circuit for Lower-Voltage Rectangular Shocks
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Solution Overview
Problem
Existing implantable defibrillators require high peak voltages for effective defibrillation, leading to the need for high voltage components and complex design rules, especially in non-transvenous devices like subcutaneous ICDs.
Innovation Solution
An implantable pulse generator with an electric circuit comprising a primary energy store, multiple secondary energy stores, and a control unit that activates switches to discharge energy via a therapeutic current path, producing a substantially rectangular pulse waveform with reduced maximum shock voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitor discharge with exponential waveform is used for defibrillation, then defibrillation function is achieved, but high peak voltages exceeding 1300 V are required
Solution Approach 1:
The patent divides the single capacitor discharge into multiple stages by introducing secondary energy stores that discharge sequentially. The primary capacitor discharges first, followed by secondary capacitors that maintain the current after the primary voltage drops, thereby segmenting the discharge process to avoid high peak voltages while maintaining defibrillation effectiveness.
Solution Approach 2:
The patent changes the voltage waveform parameters from exponential decay to a more rectangular shape by controlling the discharge timing and sequence of multiple capacitors. This parameter change allows the shock to be delivered at lower peak voltages (around 1000 V or less) while maintaining the necessary energy delivery for effective defibrillation.
2Reliability
If high voltage components are used to achieve effective defibrillation, then defibrillation threshold is met, but device complexity and design rules increase
Solution Approach 1:
The patent segments the energy storage function across multiple capacitors (primary and secondary energy stores) rather than relying on a single high-voltage capacitor. This segmentation allows each component to operate at lower voltage levels, reducing the complexity and design constraints associated with high-voltage components.
3Object-affected harmful factors
If rectangular pulse waveform is implemented, then shock voltage is reduced, but multiple energy stores and control switches are required
Solution Approach 1:
The patent combines multiple energy stores (primary and secondary capacitors) with control switches to create an integrated system that generates rectangular pulse waveforms. This merging of components allows the system to deliver shocks at reduced voltages while the control unit coordinates the switching and discharge timing to achieve the desired waveform shape.
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 solution allows for effective defibrillation with lower shock voltages, reducing the complexity and cost of implantable defibrillators, and enabling a more compact design suitable for subcutaneous ICDs.
Implementation Method 1
capacitor discharges are always used in implantable defibrillators (ICDs) for defibrillation, wherein the entire shock energy is taken from a constant capacitance over the course of the defibrillation
Data Source
AI summary
The present invention relates an implantable pulse generator comprising an electric circuit, wherein the electric circuit comprises: a primary energy store, at least one secondary energy store, and a control unit, wherein the control unit is configured to activate an electric switch in the electric circuit in such a way that, in a first interval of a first phase of a pulse delivery, the primary energy store is discharged via a therapeutic current path, and to activate an electric switch in the electric circuit in such a way that, in a second interval of the first phase of the pulse delivery, the secondary energy store is discharged via the therapeutic current path, wherein the primary energy store and the at least one secondary energy store are fixedly connected, or connectable, in series, and wherein the implantable pulse generator is designed to deliver a shock having an approximately rectangular pulse waveform.