QT Interval Correction via Probability Distribution Intersection

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Solution Overview

Problem

Existing QT correction methods, such as Bazett's and Fridericia's formulas, are inaccurate, especially at high and low heart rates, necessitating an improved solution for normalizing QT intervals across varying heart rates.

Innovation Solution

A method that computes first and second probability distributions for QT and RR intervals, identifying intersection points or minimal difference thresholds to determine corrected QT intervals, which can then be selected based on proximity to a predefined heart rate, maximum probability, or a compound relation combining probability and distance factors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional QT correction formulas (Bazett's or Fridericia's) are used, then the correction process is simple and fast, but the accuracy deteriorates especially at high and low heart rates

Engineering Contradiction:
ImproveQT correction accuracyVSAvoidcorrection method complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transforms the QT correction problem from using fixed heart rate values to using probability distributions of QT and RR intervals. By computing first and second probability distributions and finding their intersection or minimal difference points, the method adapts to varying heart rates dynamically, significantly improving accuracy across different heart rate conditions while maintaining computational feasibility through iterative optimization.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If probability distribution methods are used for QT correction, then the accuracy improves across varying heart rates, but the computational complexity increases

Engineering Contradiction:
ImproveQT correction reliabilityVSAvoidcomputational complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements feedback by using the extracted RR intervals to compute a second probability distribution that informs the QT correction process. The method iteratively refines the corrected QT values by comparing the first probability distribution (from QT intervals) with the second probability distribution (from RR intervals), using the intersection or minimal difference points as feedback to achieve reliable QT correction across varying heart rates.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent performs preliminary actions by first extracting multiple QT and RR intervals from the ECG signal, then computing their respective probability distributions before determining the corrected QT values. This preliminary computation of statistical characteristics enables the subsequent accurate determination of corrected QT intervals while managing computational complexity through structured preprocessing.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If multiple probability distributions and intersection solving are used, then the QT correction becomes independent of RR intervals, but the processing time increases

Engineering Contradiction:
ImproveQT correction independence from RRVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies partial action by computing probability distributions only for the necessary QT and RR intervals extracted from the ECG signal, rather than processing all possible data. The method finds the intersection or minimal difference points between the two distributions to determine corrected QT values, achieving RR independence while limiting processing time through selective computation and early termination when convergence is achieved.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3886695B1An apparatus and a method for QT correction
Publication Date: 2022.05.11 TAMPERE UNIV FOUND SR
  • EP3886695B1 patent drawingFigure 1~2
  • EP3886695B1 patent drawingFigure 3
  • EP3886695B1 patent drawingFigure 4

AI summary

A method for QT correction is provided, the method comprising receiving an ECG signal; extracting a plurality of beat-to-beat (RR) intervals; extracting a plurality of QT intervals; computing a first probability distribution for a range of QT values based on the plurality of QT intervals; computing a second probability distribution for a range of QT values based on the plurality of QT intervals and the plurality of RR intervals; solving one or more points, wherein the first probability distribution and the second probability distribution intersect or wherein a difference between the first probability distribution and the second probability distribution is below a pre-defined difference threshold; designating one of one or more QT values corresponding to the one or more points as a corrected QT interval for a given QT interval of the plurality of QT intervals.