Cardiac Arrhythmia Classification Using Sample Entropy

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Solution Overview

Problem

Current cardiac rhythm management systems face challenges in accurately classifying tachyarrhythmias, such as distinguishing between tachycardia and fibrillation, which is crucial for selecting appropriate therapy to restore normal cardiac function.

Innovation Solution

An implantable medical device with an arrhythmia detection and classification system that uses irregularity and complexity parameters, computed using sample entropy, to classify arrhythmias based on cycle length irregularity and morphological complexity of cardiac signals, enabling discrimination between tachycardia and fibrillation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional arrhythmia classification methods are used, then the system can detect tachyarrhythmias, but the classification accuracy between tachycardia and fibrillation is insufficient

Engineering Contradiction:
Improvearrhythmia classification accuracyVSAvoidclassification system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The classification system is divided into multiple independent analysis modules: cycle length irregularity analysis, morphological complexity analysis, and therapy selection. Each module processes specific features independently, improving classification accuracy without requiring a complete system redesign.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces sample entropy as a new dimensional parameter for analyzing cardiac signals. By computing sample entropy of cycle lengths and morphological features, the system adds a quantitative dimension to arrhythmia classification, enabling better discrimination between tachycardia and fibrillation beyond traditional rate-based methods.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If defibrillation shock pulses are delivered for all tachyarrhythmias, then life-threatening conditions are treated, but unnecessary shocks are delivered for non-life-threatening arrhythmias causing substantial discomfort

Engineering Contradiction:
Improvetherapy appropriatenessVSAvoidpatient discomfort from unnecessary shocks
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The therapy selection is made dynamic based on real-time classification results. The system continuously monitors arrhythmia characteristics and adjusts therapy delivery accordingly: ATP is delivered for tachycardia while defibrillation is reserved for fibrillation, making the treatment adaptive rather than static.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The classification system provides feedback to the therapy delivery mechanism. By analyzing cycle length irregularity and morphological complexity, the system determines whether the detected arrhythmia requires defibrillation or can be treated with less invasive ATP, creating a feedback loop that prevents unnecessary shock delivery.

Inventive Principle:
Principle #23Feedback

3Reliability

If ATP therapy is delivered for all detected tachyarrhythmias, then non-life-threatening arrhythmias are treated appropriately, but life-threatening fibrillation may not receive immediate defibrillation

Engineering Contradiction:
Improvetherapy effectivenessVSAvoidtime delay in defibrillation delivery
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary classification of the arrhythmia type before determining therapy. By analyzing cycle length irregularity and morphological complexity in advance, the system pre-determines whether ATP or defibrillation is appropriate, ensuring that life-threatening fibrillation receives immediate defibrillation without delay while ATP is reserved for suitable tachycardia cases.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS8825146B2Method and apparatus for cardiac arrhythmia classification using sample entropy
Publication Date: 2014.09.02 CARDIAC PACEMAKERS INC
  • US8825146B2 patent drawing
  • US8825146B2 patent drawing
  • US8825146B2 patent drawing

AI summary

An implantable medical device includes an arrhythmia detection and classification system that classifies an arrhythmia episode based on an irregularity parameter and/or a complexity parameter. The arrhythmia episode is detected from a cardiac signal. The irregularity parameter is indicative of the degree of cycle length irregularity of the cardiac signal and the complexity parameter is indicative of the degree of morphological complexity of the cardiac signal. One example of the irregularity parameter is an irregularity sample entropy, or a parameter related to the irregularity sample entropy, computed to indicate the cycle length irregularity. One example of the complexity parameter is a complexity sample entropy, or a parameter related to the complexity sample entropy, computed to indicate the morphological complexity. In one embodiment, the detected arrhythmia episode is classified using both the irregularity parameter and the complexity parameter.