Micro Ablation Electrode Shielding for Parasitic Capacitance

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Solution Overview

Problem

Radiofrequency ablation procedures in the heart face interference from capacitive effects, which can disrupt electrophysiologic signals and affect the accuracy of ablation processes due to electromagnetic interference and parasitic capacitance.

Innovation Solution

A flexible catheter with an ablation electrode and microelectrodes is designed, featuring an electrical shield with a coaxial layer and dielectric layer to minimize stray capacitance, along with a conductive wire lead and thermocouple for precise temperature monitoring, and a back patch electrode for generator circuit connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If microelectrodes are placed in proximity to the ablation electrode for mapping and sensing, then mapping precision and contact feedback are improved, but parasitic capacitance and electromagnetic interference increase

Engineering Contradiction:

Improvemapping precisionVSAvoidparasitic capacitance

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

An electrical shield comprising a coaxial layer and dielectric layer is introduced as an intermediary between the microelectrode wire lead and the ablation electrode. This shield acts as a mediator that blocks parasitic capacitance and electromagnetic interference from reaching the sensitive microelectrode signals, while allowing the microelectrodes to remain in close proximity for accurate mapping and contact detection.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrical shield is segmented into distinct functional layers: a coaxial layer for electromagnetic shielding and a dielectric layer for electrical isolation. This segmentation allows each layer to perform its specific function optimally - the coaxial layer blocks external electromagnetic interference while the dielectric layer prevents parasitic capacitance formation between the wire lead and ablation electrode.

Inventive Principle:

Principle #1Segmentation

2Loss of information

If wire leads connect microelectrodes to receiving circuitry for signal transmission, then data acquisition is enabled, but electromagnetic interference and signal distortion increase

Engineering Contradiction:

Improvesignal integrityVSAvoidelectromagnetic interference

Core Design Contradiction:

Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The electrical shield serves as a protective intermediary surrounding the wire lead, blocking electromagnetic interference from corrupting the microelectrode signals during transmission to the receiving circuitry. This maintains signal integrity without requiring changes to the basic wire lead connection architecture.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If the ablation electrode is activated for RF energy transmission, then ablation effectiveness is improved, but capacitive effects interfere with electrophysiologic signals

Engineering Contradiction:

Improveablation effectivenessVSAvoidcapacitive effects

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The electrical shield acts as a mediator that isolates sensitive electrophysiologic signal pathways from the high-power RF ablation field. By surrounding the microelectrode wire leads with this shield, the system can transmit full-power RF energy for effective ablation while the shield prevents capacitive coupling from distorting the simultaneous electrophysiologic recordings.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration reduces parasitic current and interference, enhancing the accuracy and effectiveness of ablation procedures by minimizing stray capacitance and maintaining signal integrity, thereby improving the precision of cardiac ablation treatments.

Implementation Method 1

Effective parasitic capacitance minimization for micro ablation electrode

Methodology Applied

Scientific EffectParasitic capacitance: Capacitance

Implementation Method 2

an electrical shield surrounding the wire lead

Methodology Applied

Scientific EffectElectrical shielding: Faraday Cage

Implementation Method 3

the microelectrode is linked to a thermocouple that provides a signal representative of a temperature of the microelectrode

Methodology Applied

Scientific EffectThermocouple effect: Seebeck Effect

Implementation Method 4

Radiofrequency (RF) ablation of the heart is a procedure that is widely used to correct problematic cardiac conditions

Methodology Applied

Scientific EffectRadiofrequency heating: Joule Heating

Implementation Method 5

ablating selected regions within the heart with RF energy transmitted via the electrode

Methodology Applied

Scientific EffectAblation: Ablation

Data Source

PatentUS11207125B2Effective parasitic capacitance minimization for micro ablation electrode

Publication Date: 2021.12.28 BIOSENSE WEBSTER (ISRAEL) LTD

AI summary

A flexible catheter has an ablation electrode disposed in its distal segment. The ablation electrode a cavity formed in its external surface, a microelectrode configured to fit into the cavity, a conductive wire lead connecting the microelectrode to receiving circuitry, and an electrical shield surrounding the wire lead. A power generator is connected to the ablation electrode and the electrical shield in a generator circuit. A back patch electrode adapted to contact with the subject is connected in the generator circuit. The microelectrodes can be active while energizing the ablation electrode.