Sense Amplifier Shielding for Arrhythmia Pacing Pulse Interference
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Solution Overview
Problem
Traditional implantable cardiac pacemakers face challenges in pacing pulse suppression performance, especially when using unipolar sensing polarity, and power consumption is high, making them less suitable for long-term use without replacement.
Innovation Solution
The implementation of multi-stage shielding switches in the sense amplifier, controlled by a temporal profile of pacing and discharging periods, to shield the amplifier from interference and reduce power consumption by operating at multiple gain levels and using current mirrors for low power operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional sense amplifiers operate with unipolar sensing polarity, then sensing coverage is improved, but pacing pulse suppression performance deteriorates
Solution Approach 1:
The filtering unit is divided into multiple filtering stages, including a first filtering stage and a second filtering stage, each with different cutoff frequencies. This segmentation allows the system to handle different frequency components of the pacing pulse interference separately, improving suppression performance while maintaining unipolar sensing capability
Solution Approach 2:
Different filtering characteristics are applied at different stages of the signal processing chain. The first filtering stage uses a higher cutoff frequency to preserve more signal content, while the second filtering stage uses a lower cutoff frequency to better suppress pacing pulse interference, creating localized optimization at each stage
2Power
If traditional analog front-end circuits are used, then signal processing capability is maintained, but power consumption increases
Solution Approach 1:
The filtering stages are configured to be dynamically activated or deactivated based on the operational mode. During pacing pulse delivery, the second filtering stage with lower cutoff frequency is activated to suppress interference. During normal sensing, the system can operate with reduced filtering, lowering power consumption while maintaining signal processing capability
Solution Approach 2:
The system changes filtering parameters (cutoff frequencies) based on operational requirements. By adjusting the cutoff frequencies of different filtering stages according to whether a pacing pulse is being delivered, the system optimizes the balance between signal processing performance and power consumption
3Reliability
If sense amplifiers are shielded from pacing pulse interference, then pacing pulse suppression performance is improved, but sensing sensitivity may deteriorate
Solution Approach 1:
The filtering unit is divided into multiple filtering stages, each with different cutoff frequencies. The first filtering stage preserves higher frequency components important for sensing, while the second filtering stage suppresses lower frequency pacing pulse interference, maintaining both sensitivity and suppression performance
Solution Approach 2:
The filtering unit combines multiple filtering stages with different characteristics to create a composite filtering system that simultaneously achieves pacing pulse suppression and signal preservation, resolving the contradiction between reliability and measurement precision
Data Source
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AI summary
The present invention relates to the field of medical devices and discloses an implantable medical device for treating arrhythmia. The implantable medical device includes a control unit and, each coupled to the control unit, a sense amplifier, a first switch and a second switch. The sense amplifier includes a polarity selection module, an amplification unit and a filtering unit, which are sequentially connected. The first switch is disposed within the polarity selection module, and the second switch within the filtering unit. The control unit is configured to shield the sense amplifier from interference from a pacing pulse signal by providing multi-stage on/off control over the first and second switches according to a pacing period and a discharging period in a pacing interval. According to embodiments of the invention, the shielding switches in the sense amplifier are switched on/off in multiple stages according to pacing and discharging periods of a pacing pulse signal so as to shield the sense amplifier from interference from the pacing pulse signal and enhance its pacing pulse signal suppression performance.