Chest Wall Accelerometer Heart Sound Detection
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Solution Overview
Problem
There is a clinical and consumer demand for a low-cost, portable technology to indicate cardiovascular and cardiorespiratory fitness, particularly for determining maximal oxygen consumption, which existing methods fail to address effectively.
Innovation Solution
A method and system using a band-pass filtered accelerometer signal to determine temporal features and measures of myocardial movement vibrations, providing output information on cardiovascular or cardiorespiratory fitness, specifically incorporating a piezoelectric element and processor to analyze chest wall vibrations and heart sounds, excluding abnormal cardiovascular functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an accelerometer is used to measure chest wall vibrations, then both low frequency SCG components and audible heart sound components are simultaneously sampled, but the heart sounds are dominated by the high intensity of the low-frequency vibrations making them difficult to detect
Solution Approach 1:
The patent extracts the harmful low-frequency vibration components from the accelerometer signal through band-pass filtering (cutoff frequencies 10-20 Hz), isolating the heart sound components for separate analysis. This allows the heart sounds to be detected without being dominated by the intense SCG vibrations.
Solution Approach 2:
The patent applies different processing approaches to different frequency components of the accelerometer signal. Low-frequency components (below 10-20 Hz) are filtered out, while higher frequency components (above 10-20 Hz) containing heart sounds are preserved and analyzed separately, allowing each component to be optimized for its specific diagnostic purpose.
2Measurement precision
If high pass filtering is applied with a lower cutoff of 50 Hz to reveal heart sounds, then heart sounds are revealed, but SCG components below this frequency are lost
Solution Approach 1:
The patent segments the accelerometer signal into different frequency components using band-pass filtering. The heart sound components (above 10-20 Hz) are separated from the SCG components (below 10-20 Hz), allowing both to be analyzed independently with appropriate processing methods for each type of cardiovascular information.
3Adaptability or versatility
If a band-pass filter with lower cutoff below 1 Hz and upper cutoff 60-500 Hz is used, then both SCG and heart sound components are preserved, but the signal contains mixed cardiovascular information requiring separate processing
Solution Approach 1:
The patent segments the preserved signal into distinct SCG and heart sound components based on their frequency characteristics. By using band-pass filtering with cutoff frequencies of 10-20 Hz, the system separates the low-frequency SCG vibrations from the higher-frequency heart sounds, enabling independent analysis of each component despite both being present in the original accelerometer signal.
Solution Approach 2:
The patent applies different analysis methods to different portions of the frequency spectrum. Low-frequency components are processed for SCG analysis (temporal features, intervals), while higher frequency components are processed for heart sound analysis (murmur detection, valve events), allowing each cardiovascular function to be optimized for its specific diagnostic requirements.
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 accurate and non-invasive assessment of cardiovascular fitness, including maximal oxygen consumption (VO2 Max), through the analysis of signal strength and temporal features, offering a portable and cost-effective solution for monitoring cardiorespiratory health.
Implementation Method 1
Specifically incorporating a piezoelectric element and processor to analyze chest wall vibrations and heart sounds
Data Source
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AI summary
A technology for quantifying, or determining an indication of, cardiorespiratory fitness is disclosed. A signal portion is obtained from a signal recorded with an accelerometer placed on the chest of a person. The accelerometer measures accelerations and vibrations of the chest wall of the person caused by myocardial movement. A maximum value is determined in the signal portion, and output information is provided indicating cardiorespiratory fitness based on the maximum value.