Noninvasive Electromechanical Delay Measurement via Dual PPG and EKG

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Solution Overview

Problem

Current methods for measuring electromechanical delay of the heart, which is crucial for assessing heart performance and detecting conditions like cardiac failure, rely on invasive techniques or lack precision in non-invasive monitoring, particularly in calculating blood pressure using photoplethysmograph (PPG) signals.

Innovation Solution

A system utilizing at least two PPG sensors and an EKG sensor to calculate electromechanical delay by determining differential pulse transit time (DPTT) and EKG to PPG transit time values, allowing for continuous non-invasive blood pressure monitoring and alert triggering based on changes in these values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If invasive techniques are used to measure electromechanical delay, then measurement precision is improved, but patient discomfort and procedural complexity increase

Engineering Contradiction:

Improveelectromechanical delay measurement precisionVSAvoidpatient discomfort

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces invasive mechanical measurement techniques with non-invasive optical and electrical sensing. Specifically, it uses photoplethysmograph (PPG) sensors to detect pulse waveforms optically and electrocardiogram (ECG) electrodes to detect electrical activity, eliminating the need for invasive catheter-based measurements while maintaining measurement precision for electromechanical delay

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces intermediate measurement signals (PPG pulse waveforms and ECG electrical signals) that serve as mediators to indirectly measure electromechanical delay. By detecting the time difference between ECG Q-wave onset and PPG pulse arrival through these intermediate signals, the system achieves precise measurement without direct invasive contact with heart structures

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If single PPG signal is used for blood pressure calculation, then device complexity is reduced, but measurement reliability decreases due to signal degradation

Engineering Contradiction:

Improvesensor configuration complexityVSAvoidblood pressure measurement reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent places multiple PPG sensors at different anatomical locations (e.g., finger and wrist) to measure pulse waveforms from different vascular segments. Each sensor provides locally-specific pulse quality information, allowing the system to select or combine signals based on local signal quality metrics to maintain reliable blood pressure measurement even when one sensor experiences degradation

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system proactively acquires pulse waveforms from multiple PPG sensors simultaneously before signal degradation occurs. This redundant measurement approach cushions against potential signal loss by having backup signals ready, ensuring continuous reliable blood pressure monitoring without interruption even when one sensor's signal degrades

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Measurement precision

If multiple PPG signals are processed simultaneously, then measurement precision is improved, but computational complexity increases

Engineering Contradiction:

Improveelectromechanical delay calculation precisionVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the signal processing task into distinct segments: first processing each PPG signal independently to extract pulse arrival times, then using these extracted features to calculate electromechanical delay. This segmentation simplifies the overall computation by breaking down the complex multi-signal processing into manageable independent steps that can be executed sequentially or in parallel

Inventive Principle:

Principle #1Segmentation

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

Enables precise, non-invasive measurement of electromechanical delay and blood pressure, reducing patient discomfort and improving monitoring accuracy, with the ability to detect changes that may indicate cardiac issues.

Implementation Method 1

An electrocardiogram (EKG) signal may be used to detect heart electrical activity

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

Photoplethysmograph (PPG) signals may be used to detect heart mechanical activity

Methodology Applied

Scientific EffectPhotoplethysmography: Absorption (EM radiation)

Data Source

PatentUS9451887B2Systems and methods for measuring electromechanical delay of the heart

Publication Date: 2016.09.27 NELLCOR PURITAN BENNETT IRELAND

AI summary

Systems and methods are disclosed herein for measuring the electromechanical delay of the heart of a patient. An electrocardiogram (EKG) signal may be used to detect heart electrical activity. Photoplethysmograph (PPG) signals may be used to detect heart mechanical activity. The electromechanical delay may be calculated based at least in part on the timing of an EKG signal and at least two PPG signals.