PFA Impedance Path Control for Accurate Tissue Ablation
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Solution Overview
Problem
Existing pulsed field ablation (PFA) systems face challenges in delivering electric fields with variable impedance paths, leading to inaccurate tissue impedance measurements and suboptimal ablation results due to parasitic and neutral electrode impedances.
Innovation Solution
A method and system for determining currents and excitation voltages in PFA systems by considering tissue and parasitic impedances, using an impedance matrix to calculate input resistances and voltages, allowing for variable impedance paths and precise ablation control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional PFA systems deliver electric fields without accounting for parasitic and neutral electrode impedances, then the system structure remains simple, but the ablation accuracy deteriorates due to inaccurate tissue impedance measurements
Solution Approach 1:
The patent segments the total impedance into distinct components: tissue impedance, parasitic impedance (from catheter and leads), and neutral electrode impedance. By measuring and calculating each component separately through multiple circuit paths, the system achieves accurate tissue impedance measurement while accounting for all impedance sources, thereby improving ablation accuracy without requiring complete system redesign.
Solution Approach 2:
The patent introduces an intermediary computational model that acts as a mediator between the complex multi-path impedance measurements and the final ablation control. This model calculates tissue impedance by subtracting measured parasitic and neutral electrode impedances from total impedance measurements, providing accurate real-time feedback for precise ablation delivery without directly modifying the physical ablation mechanism.
2Adaptability or versatility
If PFA systems use fixed impedance paths, then the control system remains simple, but the adaptability to different tissue conditions deteriorates
Solution Approach 1:
The patent implements dynamic impedance path selection and calculation, where the system adapts to different tissue conditions by measuring impedance through multiple configurable circuit paths. The control system dynamically adjusts which measurement paths are active and how impedances are combined based on real-time tissue conditions, enabling versatile adaptation without requiring a completely reconfigurable hardware architecture.
Solution Approach 2:
The patent changes the measurement parameters by applying test signals at different frequencies and through different electrode configurations to separately characterize parasitic and tissue impedances. By varying measurement parameters rather than hardware topology, the system achieves adaptability to different tissue conditions while maintaining relatively simple control circuitry.
3Measurement precision
If PFA systems ignore parasitic impedances in circuit paths, then the measurement process remains simple, but the tissue impedance measurement accuracy deteriorates
Solution Approach 1:
The patent extracts parasitic impedance components from the total impedance measurement by measuring them separately through dedicated test circuit paths. By taking out the parasitic impedance measurement from the combined tissue-plus-parasitic measurement, the system achieves accurate tissue impedance determination while adding only moderate measurement system complexity through additional test paths and signal processing.
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
Enables precise delivery of electric fields with variable impedance paths, improving ablation accuracy and reducing collateral tissue damage by accounting for parasitic and neutral electrode effects.
Implementation Method 1
PFA includes application of short pulsed electric fields (PEF), which may reversibly or irreversibly destabilize cell membranes through electro-permeabilization
Implementation Method 2
an electrosurgical generator configured to deliver electrical energy to the target tissue through an electrosurgical hand piece
Data Source
AI summary
A method and pulsed field ablation (PFA) system configured to provide variable impedance paths for delivery of electric fields to patient tissue using a PFA catheter are disclosed. According to one aspect, a method includes determining a current for each of a plurality of circuit paths, each circuit path including two electrodes. Each current may be determined based at least in part on: a desired voltage between the two electrodes; a tissue impedance between the two electrodes; and a parasitic impedance associated with the circuit path. The method also includes determining at least one of an excitation voltage and an input resistance for each circuit path of the plurality of circuit paths based at least in part on the determined current for the circuit path, parasitic impedances associated with the circuit path and a tissue impedance between the two electrodes in the circuit path.