Optical Pulse Plethysmogram for Left Ventricular Outflow Tract Detection
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Solution Overview
Problem
Current methods for diagnosing structural and valvular abnormalities in the left ventricular outflow tract are invasive, costly, and inefficient, particularly in asymptomatic patients, leading to delayed detection and potential irreversible damage due to the reliance on expensive tests like echocardiography and cardiac catheterization.
Innovation Solution
A noninvasive optical pulse plethysmogram system that uses peripherally attached speckle sensors to measure blood flow and volume, processing these signals to determine the presence and severity of left ventricular outflow tract abnormalities, including aortic stenosis, without the need for direct heart imaging or invasive pressure measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If invasive methods like cardiac catheterization are used to diagnose left ventricular outflow tract abnormalities, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses pulse waveforms as an intermediary to indirectly assess left ventricular outflow tract abnormalities. Instead of directly measuring pressure and flow at the aortic valve (invasive), the system measures peripheral pulse waveforms and analyzes their characteristics (rise time, area, morphology) to infer valve area and detect stenosis. This intermediary approach maintains diagnostic accuracy while eliminating invasive procedures.
Solution Approach 2:
The patent replaces the mechanical invasive measurement system (catheters, pressure transducers) with an optical/electronic system that uses photodetectors to measure pulse waveforms. The mechanical intrusion is substituted with non-invasive optical detection and computational analysis of waveform characteristics to achieve the same diagnostic goal.
2Measurement precision
If echocardiography with doppler interrogation is used to diagnose aortic stenosis, then measurement precision is improved, but loss of time increases due to complicated diagnostic pathways
Solution Approach 1:
The patent performs preliminary analysis of pulse waveform characteristics (rise time, area, morphology) that are directly related to valve area and stenosis severity. By pre-establishing the relationships between waveform features and valve pathology, the system enables rapid screening and triage decisions without requiring the full echocardiography workflow, reducing time to initial diagnosis.
Solution Approach 2:
Instead of using direct imaging (echocardiography) to infer flow characteristics, the patent inverts the approach by using peripheral flow waveform characteristics to infer central valve area and stenosis. This indirect inference approach simplifies the diagnostic pathway while maintaining accuracy.
3Measurement precision
If direct assessment of blood flow characteristics at the aortic valve is performed, then measurement precision is improved, but ease of operation deteriorates due to invasive requirements
Solution Approach 1:
The patent uses peripheral pulse waveforms as an intermediary to assess central aortic valve function. Instead of placing sensors directly at the aortic valve (complex and invasive), the system measures easily accessible peripheral pulse waves and uses their characteristics (rise time, area, morphology) to infer valve area and detect abnormalities, maintaining precision while improving ease of operation.
Solution Approach 2:
The patent makes a single peripheral pulse waveform measurement serve multiple diagnostic functions: assessing valve area, detecting stenosis, evaluating flow characteristics, and monitoring disease progression. This multi-functionality from a simple non-invasive measurement improves ease of operation while maintaining comprehensive assessment capability.
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 early detection and quantitative assessment of left ventricular outflow tract abnormalities, reducing the risk of irreversible damage and improving diagnostic efficiency by providing a simple, cost-effective, and noninvasive screening method for clinicians.
Implementation Method 1
a peripherally attached noninvasive optical sensor system...configured to measure an optical pulse plethysmogram
Implementation Method 2
optical pulse plethysmogram sensitive to both the systolic pulse wave and reflected pulse waves
Data Source
AI summary
Embodiments provide a reliable, convenient, noninvasive, and cost-effective determination of structural and valvular abnormalities in the left ventricular outflow tract. Embodiments obtain a noninvasive optical pulse plethysmogram from the systolic and diastolic phases of the cardiac cycle for subsequent morphologic waveform analysis to determine left ventricular outflow tract anomalies. Left ventricular outflow tract abnormalities alter the rate of increase in flow during early systole and decrease in flow during late systole. These flow variances at the aortic valve are amplified as the pulse wave moves to the periphery due to a combination of the ventricular-aortic interaction, pulse augmentation, and reflections at branching vessels and changes in diameter. The invention addresses historical limitations in the noninvasive determination of structural and valvular abnormalities in the left ventricular outflow tract by using one or more of (1) improved optical measurement systems, (2) peripheral sampling locations that maximize signal differences, (3) volitional patient maneuvers to improve the diagnostic ability of the system, and (4) pulse enhancement techniques. The resulting test system can be used to determine the presence of abnormalities and to diagnose the type of abnormality. The ability to more efficiently and effectively diagnose aortic stenosis, the most common abnormality, in the primary care clinic will result in fewer patients experiencing complications such as heart failure, heart attack, and sudden death.