Configurable Capacitor System for Pacing Artifact Reduction

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Solution Overview

Problem

Cardiac rhythm management devices face challenges in reliably sensing evoked responses due to pace pulse lead polarization artifacts, especially in configurations without separate electrodes for sensing, which can affect the accuracy of auto-capture and auto-threshold modes.

Innovation Solution

The implementation of a configurable capacitor system that switches between different capacitance values during evoked-response sensing modes, using a smaller coupling capacitor for improved sensing visibility while maintaining a larger capacitor for non-sensing modes, and the ability to borrow capacitors from other pacing channels to optimize energy delivery and reduce artifacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If a larger coupling capacitor is used for energy delivery, then the pacing pulsewidth duration is maintained, but the visibility of evoked response signals is reduced due to lead polarization artifacts

Engineering Contradiction:

Improvepacing pulsewidth durationVSAvoidevoked response signal visibility

Core Design Contradiction:

Duration of action of moving objectVSMeasurement precision

Solution Approach 1:

The patent implements dynamic switching between two capacitor values (first and second capacitance values) based on the operational mode. During evoked-response sensing modes, the smaller capacitance value is selected to improve signal visibility. During non-sensing modes, the larger capacitance value is selected to maintain pacing pulsewidth duration. This dynamic reconfiguration resolves the contradiction by adapting the capacitor value to the current operational requirements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the capacitance parameter of the coupling capacitor based on the operational mode. By switching between different capacitance values (first and second capacitance values), the system optimizes both energy delivery and sensing performance at different times, resolving the contradiction between maintaining pulsewidth duration and improving signal visibility.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If a smaller coupling capacitor is used for evoked-response sensing, then the visibility of evoked response signals is improved, but the pacing pulsewidth duration may be reduced

Engineering Contradiction:

Improveevoked response signal visibilityVSAvoidpacing pulsewidth duration

Core Design Contradiction:

Measurement precisionVSDuration of action of moving object

Solution Approach 1:

The system dynamically switches capacitor values based on operational mode. When evoked-response sensing is required, the smaller capacitance value is used to improve signal visibility. When energy delivery is the priority, the larger capacitance value is used to maintain adequate pacing pulsewidth duration. This temporal separation of requirements resolves the contradiction.

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If separate electrodes for sensing are used, then the accuracy of auto-capture and auto-threshold modes is improved, but the device complexity increases

Engineering Contradiction:

Improvesensing accuracyVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the existing electrodes multi-functional by using them for both pacing and sensing purposes. The same electrodes that deliver pacing pulses also sense evoked responses, eliminating the need for separate sensing electrodes. Combined with capacitor switching, this approach improves sensing accuracy without increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent converts the harmful lead polarization artifacts into a manageable parameter by switching capacitor values. The artifacts are still present during pacing, but by using a smaller capacitance value during sensing modes, the system can detect evoked responses despite the artifacts, effectively converting the harmful effect into a controllable condition.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 approach enhances the visibility of evoked response signals by reducing artifacts and maintaining effective pacing pulsewidth duration, ensuring reliable auto-capture and auto-threshold operations in size-constrained implantable devices.

Implementation Method 1

A first capacitor can be coupled to the first electrostimulation voltage generator, and configured to be capable of storing the first electrostimulation voltage

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

A cardiac rhythm management device can electrostimulate excitable heart tissue cells adjacent to the electrode of the lead coupled to the rhythm management device

Methodology Applied

Scientific EffectElectrical stimulation: Electric Field

Data Source

PatentUS8948866B2Configuration of pacing output channels

Publication Date: 2015.02.03 CARDIAC PACEMAKERS INC

AI summary

During auto-threshold, autocapture, or other evoked response sensing, post-pace artifact is reduced by using a smaller coupling capacitor value than what is used when not in such an evoked response sensing configuration. This can be accomplished by borrowing another capacitor for use as the coupling capacitor. The borrowed capacitor can be a backup pacing capacitor from the same or a different pacing channel. The borrowed capacitor can also be a coupling capacitor from a different pacing channel.