Dynamic Morphology Template Update for Cardiac Rhythm Discrimination

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current implantable cardiac stimulation devices face challenges in accurately distinguishing between ventricular and supraventricular tachyarrhythmias due to variability in R-wave morphology, leading to potential misidentification and inappropriate therapy delivery.

Innovation Solution

A method for updating morphology templates in implantable cardiac stimulation devices using both weighted and non-weighted candidate templates, based on ensemble averaging and fiducial point alignment, to reflect central and changing R-wave morphologies, ensuring accurate discrimination between ventricular and supraventricular tachyarrhythmias.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If morphology templates are updated frequently to adapt to changing R-wave morphology, then the adaptability of the discrimination system improves, but the reliability of template accuracy deteriorates due to variability in R-wave shape

Engineering Contradiction:

Improveadaptability to changing R-wave morphologyVSAvoidreliability of template accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The template update mechanism is made dynamic by automatically adjusting the weighting between old and new templates based on morphology correlation. When correlation is high, updates are gradual; when correlation is low, updates are more aggressive. This dynamic adaptation resolves the contradiction by allowing the system to be both reliable (when morphology is stable) and adaptable (when morphology changes).

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of template weighting dynamically. Instead of using a fixed update rule, the system adjusts the weighting parameter based on the calculated correlation between current and historical R-wave morphologies. This parameter change enables the system to maintain reliability during stable periods and adapt during changing periods.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If morphology templates are updated conservatively to maintain accuracy, then the reliability of discrimination improves, but the adaptability to long-term morphology changes deteriorates

Engineering Contradiction:

Improvereliability of discrimination accuracyVSAvoidadaptability to long-term morphology changes

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system performs preliminary correlation analysis before executing template updates. By calculating the correlation between current R-wave morphology and historical templates in advance, the system determines the appropriate update strategy. This preliminary action ensures that updates are only performed when necessary and appropriate, maintaining reliability while enabling adaptability when needed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from morphology correlation analysis to control the template update process. The correlation metric provides feedback on whether the current template accurately represents ongoing morphology, and this feedback drives the weighted combination strategy. This feedback mechanism ensures reliable discrimination while adapting to long-term changes.

Inventive Principle:

Principle #23Feedback

3Device complexity

If simple template replacement is used to update morphology templates, then the device complexity is reduced, but the measurement precision of R-wave morphology discrimination deteriorates

Engineering Contradiction:

Improvecomplexity of template update processVSAvoidprecision of R-wave morphology discrimination

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary mechanism - the weighted combination of old and new templates - that bridges simple replacement and complex adaptive filtering. The weighting factor acts as an intermediary parameter that can be adjusted based on correlation, providing a middle ground between simplicity and precision that resolves this contradiction.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Measurement precision

If extensive morphology analysis is performed to improve discrimination accuracy, then the measurement precision improves, but the productivity of the device is reduced due to increased processing requirements

Engineering Contradiction:

Improveprecision of arrhythmia discriminationVSAvoidprocessing efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The system performs partial morphology analysis by focusing on correlation metrics rather than complete waveform analysis. This partial action approach provides sufficient precision for template updates without the excessive processing requirements of full waveform comparison, resolving the contradiction between precision and productivity.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS9220434B2Systems and methods for selectively updating cardiac morphology discrimination templates for use with implantable medical devices

Publication Date: 2015.12.29 PACESETTER INC

AI summary

Techniques are provided for updating a morphology template used to discriminate abnormal cardiac rhythms. In one example, a non-weighted candidate morphology template is generated based on far-field R-wave morphology. A weighted candidate morphology template is generated based on an ensemble average of the non-weighted candidate morphology template and a previous (i.e. active) morphology template. The previous morphology template is then selectively updated based on a comparison of additional R-waves against both the non-weighted and the weighted candidate templates. Thereafter, abnormal cardiac rhythms such as ventricular tachycardia and supraventricular tachycardia are discriminated using the updated morphology template based on newly-detected far-field R-waves. These techniques provide a method for updating the morphology discrimination template in response to long-term changes in morphology due to cardiac remodeling or cardiac disease progression.