Ballistocardiogram-Based Aortic Pulse Transit Time Estimation
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Solution Overview
Problem
Current methods for measuring aortic pulse transit time (PTT) are invasive, uncomfortable, and require skilled placement of sensors, limiting their use for long-term measurements.
Innovation Solution
Estimating aortic PTT from time intervals measured between fiducial points exclusively obtained from the ballistocardiogram (BCG), eliminating the need for additional pulse wave sensors and allowing for more comfortable and efficient measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are placed at carotidal and femoral sites to measure PTT, then measurement precision is improved, but ease of operation deteriorates due to skilled placement requirements and discomfort
Solution Approach 1:
The patent replaces the mechanical contact-based sensor placement system (requiring skilled placement at specific anatomical sites) with a ballistocardiography-based system that uses whole-body motion detection. The BCG system detects cardiac ejection effects on the body's center of gravity, eliminating the need for precise sensor placement at carotidal and femoral sites while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces ballistocardiography as an intermediary measurement method. Instead of directly measuring pulse wave arrival at specific arterial sites, the system uses BCG to detect the mechanical effects of cardiac ejection on the body, which serves as an intermediate indicator that correlates with aortic PTT but requires no direct arterial access or precise sensor placement.
2Measurement precision
If multiple sensors are used for PTT measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the essential measurement information (cardiac ejection timing and pulse wave propagation) from the complex multi-sensor system and consolidates it into a single BCG measurement platform. By taking out only the necessary mechanical motion detection capability, the system achieves accurate aortic PTT measurement without requiring multiple sensors placed at different anatomical sites.
3Measurement precision
If sensors are placed in direct contact with skin at arterial sites, then measurement precision is improved, but object-affected harmful factors increase due to discomfort and physiological effects during prolonged measurement
Solution Approach 1:
The patent replaces the invasive mechanical contact measurement system with a non-contact or minimal-contact BCG-based system. By measuring whole-body mechanical responses to cardiac ejection rather than directly contacting arterial sites, the system eliminates skin irritation, discomfort, and physiological effects associated with prolonged sensor contact while maintaining measurement precision.
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 faster, more comfortable, and accurate measurement of aortic PTT over long periods, improving the assessment of arterial elasticity and related health indicators.
Implementation Method 1
The BCG can be obtained from different systems, some of them implemented with sensors embedded in daily use objects such as bodyweight scales, chairs or beds
Implementation Method 2
a photoplethysmograph (PPG) or an impedance plethysmograph (IPG) that detect local volume changes due to the arrival of the pressure pulse
Implementation Method 3
an arterial tonometer that measures the pressure that a superficial artery exerts to a force sensor in close contact to it
Data Source
AI summary
A method and apparatus is proposed to estimate the aortic pulse transit time (PTT) from only time intervals measured between fiducial points of the longitudinal ballistocardiogram (BCG) without the need to apply any sensor to the area where the arrival of the arterial pulse waveform is to be detected. From the longitudinal BCG of a subject, which can be obtained by means of sensors integrated in a single element with which the subject's body comes into contact, two fiducial points of the BCG waveform are detected in which one of the points is associated with the arrival of the arterial pulse wave to a zone proximal to the heart and the other is associated with the arrival of said arterial pulse wave to a distal zone, respectively. From the time interval between the two points, an estimate of the aortic (carotid-femoral) PTT is provided either directly or through a process of previous calibration.