Implanted Sensor Pulse Arrival Time Central Blood Pressure
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Solution Overview
Problem
Current methods cannot reliably measure central arterial blood pressure non-invasively, relying on incomplete peripheral blood pressure measurements, which limits patient treatment effectiveness due to variations in vascular properties.
Innovation Solution
An implantable system using sensors at multiple arterial sites and heart electrodes to estimate central arterial blood pressure by measuring pulse arrival times and velocities, allowing for the calculation of central pulse wave velocity and pressure based on peripheral pulse wave velocity and anatomical distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If peripheral arterial blood pressure is measured using a cuff, then blood pressure can be easily measured, but the measurement may differ significantly from central blood pressure due to vascular compliance and resistance variations
Solution Approach 1:
The patent segments the arterial system into multiple measurement sites (first site and second site at different distances from the heart) and measures pulse arrival times at each site separately. This segmentation allows the system to calculate pulse wave velocity across different arterial segments, which then enables estimation of central blood pressure while accounting for local vascular properties at each site.
Solution Approach 2:
The patent introduces pulse wave velocity as an intermediary parameter that mediates between peripheral blood pressure measurements and central blood pressure estimation. By measuring the time for pulse waves to travel between multiple arterial sites and calculating the velocity, the system can translate peripheral measurements into central blood pressure estimates, accounting for the effects of vascular compliance and resistance.
2Measurement precision
If multiple implanted sensors are used to measure pulse arrival times at different arterial sites, then central blood pressure estimation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent designs the sensor system with multi-functionality, where the same implanted sensors at different sites serve multiple purposes: measuring pulse arrival times for central blood pressure estimation, and potentially monitoring other cardiovascular parameters. This universal approach allows accurate CBP estimation without requiring separate dedicated systems for each measurement function.
Solution Approach 2:
The patent performs preliminary measurements of pulse arrival times at multiple sites during an initial calibration period when the patient is in a known physiological state. These preliminary data are used to establish baseline pulse wave velocities and timing relationships, which are then stored and used for subsequent central blood pressure estimations without requiring continuous complex processing during normal operation.
3Object-affected harmful factors
If pulse wave velocity is calculated using anatomical distances and pulse arrival times, then central blood pressure can be estimated non-invasively, but the method requires precise measurement of multiple parameters
Solution Approach 1:
The patent replaces direct mechanical pressure measurement in the aorta (which would be invasive) with an optical/electrical measurement system that detects pulse wave propagation through arterial walls and blood flow. By using sensors to detect pulse arrival times and calculating wave velocity based on known or measured anatomical distances, the system substitutes invasive mechanical measurement with non-invasive temporal and spatial measurement, eliminating the need for direct aortic catheterization.
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 estimation of central arterial blood pressure, providing critical cardiovascular health indicators without invasive procedures, improving treatment efficacy by accounting for individual vascular properties.
Implementation Method 1
using an implanted optical sensor at the first site to obtain a first photoplethysmography (PPG) signal indicative of changes in arterial blood volume at the first site
Implementation Method 2
using implanted electrodes to obtain a signal indicative of electrical activity of the patient's heart
Implementation Method 3
A time t1 is determined from a predetermined feature of the signal indicative of electrical activity to a predetermined feature of one of the first and second signals, the time t1 being a first pulse arrival time (PAT1) indicative of how long it takes a pulse wave to travel from the patient's aorta to one of the first and second sites
Data Source
AI summary
In specific embodiments, a method for estimating central arterial blood pressure (CBP), comprises determining a time t1 from a predetermined feature of a signal indicative of electrical activity to a predetermined feature of one of a first and second signals, the time t1 being a first pulse arrival time (PAT1) indicative of how long it takes a pulse wave to travel from the aorta to one of a first and second sites, determining a time t2, the time t2 being a second pulse arrival time (PAT2) indicative of how long it takes a pulse wave to travel from the aorta to the other of the first and second sites, and (f) estimating the patient's central arterial blood pressure (CBP) based on the first pulse arrival time (PAT1) and the second pulse arrival time (PAT2).