Heart Sound Center of Mass Monitoring via Accelerometer
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Solution Overview
Problem
Conventional heart sound monitoring techniques face challenges in accurately detecting heart sound characteristics due to signal quality issues related to the location and orientation of implantable medical devices, leading to inaccuracies in determining heart function parameters.
Innovation Solution
A system and method that utilize electrodes and accelerometers to sense electrical cardiac activity and heart sound signals, calculating the center of mass for S1 and S2 heart sounds to determine electromechanical activation time and systolic interval, thereby improving the accuracy of heart function monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional heart sound monitoring techniques are used to monitor heart sound duration, amplitude, and intervals, then the monitoring system can provide basic cardiac information, but the measurement precision deteriorates when signal quality is inferior due to IMD location and orientation
Solution Approach 1:
The patent introduces an accelerometer as an intermediary sensor to detect heart sounds mechanically through body wall vibrations, rather than relying on acoustic sensors that are sensitive to IMD location and orientation. The accelerometer serves as a mediator that converts mechanical vibrations into electrical signals, providing more reliable heart sound detection independent of device positioning.
Solution Approach 2:
The patent replaces the conventional acoustic heart sound sensing mechanism with a mechanical vibration detection approach using an accelerometer. This substitution transforms the sensing principle from acoustic pressure detection to mechanical acceleration measurement, which is less affected by the IMD's location and orientation within the body.
2Loss of information
If the area under the curve (AOC) method is used to analyze S1 and S2 heart sounds, then the analysis can be performed, but the ability to determine specific time points for measuring intervals deteriorates
Solution Approach 1:
The patent applies preliminary action by detecting the R-wave peak from ECG signals before analyzing the heart sounds. This R-wave detection serves as a preliminary marker that establishes a reference time point, allowing subsequent heart sound analysis to be precisely timed relative to the electrical cardiac event, thereby preserving time point information.
Solution Approach 2:
The patent creates a temporal copy or reference relationship between the ECG R-wave and the heart sounds. By using the R-wave peak as a reference point and measuring intervals from this copied time marker to specific heart sound features, the system preserves precise time point information that would otherwise be lost in AOC analysis.
3Measurement precision
If conventional heart sound analysis is performed without considering R-wave timing, then the analysis process is simpler, but the accuracy of determining electromechanical activation time and systolic interval deteriorates
Solution Approach 1:
The patent merges the analysis of electrical cardiac signals (ECG) with mechanical heart sound signals by synchronizing them in time. The R-wave detection from ECG is combined with accelerometer-based heart sound detection, creating an integrated analysis that simultaneously considers both electrical and mechanical aspects of cardiac function to accurately determine electromechanical activation time.
Solution Approach 2:
The patent performs preliminary detection of the R-wave peak from ECG signals before analyzing the heart sounds. This preliminary electrical signal detection establishes a reference point that guides the subsequent mechanical signal analysis, enabling accurate determination of electromechanical activation time without overly complicating the overall processing workflow.
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
Enhances the accuracy of heart function monitoring by overcoming signal quality issues and providing precise measurements of key heart function parameters, such as electromechanical activation time and systolic interval, leading to better clinical assessments.
Implementation Method 1
Miniaturized accelerometers have been proposed, that utilize micro-electromechanical system (MEMS) technology, to detect heart sounds while the accelerometers are implanted within an IMD
Implementation Method 2
electrodes configured to sense electrical cardiac activity (CA) signals over a period of time
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A system and method for monitoring heart function based on heart sounds (HS) is provided. The system includes electrodes (1114, 1126, 1412, 1426) configured to sense electrical cardiac activity (CA) signals over a period of time. An HS sensor (1270, 1425) is configured to sense HS signals over the period of time. The system includes memory (1260, 1422) to store specific executable instructions and includes one or more processors (1220, 1420) that, when executing the specific executable instructions, is configured to: identify a characteristic of interest (COI) of a heartbeat from the CA signals. The processors (1220, 1420) overlay a HS search window onto an HS segment of the HS signals based on the COI from the CA signals and calculate a center of mass (COM) for at least one of S1 or S2 HS based on the HS segment of the HS signals within the search window to obtain a corresponding at least one of S1 COM or S2 COM. The processors (1220, 1420) calculate at least one of an electromechanical activation time (EMAT) or a systolic interval (SI) based on the at least one of S1 COM or S2 COM and record the at least one of the EMAT or SI.