Implantable Cardiac Sensing With Sub-Windows for Atrial Event Detection
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Solution Overview
Problem
Existing implantable medical devices face challenges in reliably sensing atrial events for ventricular pacing due to weak signal amplitudes and noise interference, particularly when placed in the ventricle, which affects atrioventricular synchrony.
Innovation Solution
An implantable medical device with a sensor arrangement and processing circuitry that divides the peak detection window into sub-windows to determine a peak amplitude by excluding contaminated signal portions, using separate processing channels for near-field and far-field signals, and dynamically adjusts the sense threshold based on peak amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the implantable medical device is placed in the ventricle to provide ventricular pacing, then the device can achieve proper positioning for pacing function, but the sensing of atrial events becomes difficult due to weak signal amplitudes and distance from the atrium
Solution Approach 1:
The patent divides the peak detection window into multiple sub-windows to separately analyze different portions of the cardiac cycle. This segmentation allows the device to identify and exclude contaminated signal portions (such as those affected by ventricular activity) while preserving clean atrial event signals, thereby improving detection accuracy despite the challenging ventricular placement
Solution Approach 2:
The patent applies different processing strategies to different time periods within the cardiac cycle by defining specific sub-windows. Each sub-window is tailored to capture specific physiological events (atrial contraction, ventricular contraction, recovery phases) with appropriate sensitivity thresholds, enabling precise local analysis of signal quality at different temporal locations
2Adaptability or versatility
If the device uses mechanical event sensing (motion, sound, pressure) to detect atrial contractions, then it can potentially sense atrial activity, but the small signal volume and distance from the atrium make detection difficult
Solution Approach 1:
The patent introduces an intermediary processing layer that analyzes the characteristics of mechanical sensor signals within defined sub-windows. This intermediary processing identifies signal patterns corresponding to atrial events while filtering out noise and contaminated portions, effectively mediating between the weak mechanical sensor output and the decision-making logic for pacing control
3Measurement precision
If the device divides the peak detection window into sub-windows and excludes contaminated signal portions, then the precision of atrial event detection is improved, but the complexity of signal processing increases
Solution Approach 1:
The patent segments the complex signal processing task into manageable sub-windows, each with specific analysis rules. This segmentation reduces the computational burden by processing smaller time intervals independently with simpler algorithms, while still achieving comprehensive analysis of the entire cardiac cycle through the combination of sub-window results
4Reliability
If the device dynamically adjusts the sense threshold based on peak amplitudes, then the reliability of atrial event detection is enhanced, but the computational requirements and processing time increase
Solution Approach 1:
The patent performs preliminary analysis of signal characteristics within sub-windows to establish expected peak amplitude ranges before making threshold adjustment decisions. This preliminary action allows the device to pre-calculate appropriate threshold values based on observed signal patterns, reducing the computational burden during real-time operation and minimizing processing time delays
Data Source
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AI summary
An implantable medical device (1) configured to provide for an intracardiac function comprises a body (10), a sensor arrangement arranged on the body (10) and configured to receive a cardiac sense signal (S2), and a processing circuitry (15) operatively connected to the sensor arrangement. The processing circuitry (15) is configured to process the cardiac sense signal (S2) received using the sensor arrangement to detect a signal deflection in the cardiac sense signal (S2) potentially indicative of an atrial event (As) caused by atrial activity, and to start a peak detection window (PDW) based on the detection of said signal deflection for determining a peak amplitude (PA) associated with said atrial event (As). The peak detection window (PDW) comprises one or more sub-windows (Pi, Pi+1,...), the processing circuitry (15) being configured to determine a candidate peak value in each sub-window (Pi, Pi+1,...) and to set the peak amplitude (PA) based on the valid candidate peak values of the one or more consecutive sub-windows (Pi, Pi+1,...).