Leadless Pacemaker Atrial Detection via Multi-Timer Segmentation
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Solution Overview
Problem
Leadless pacemakers face challenges in detecting atrial events due to small signal sizes and asynchronous atrial and ventricular activity, making reliable VDD pacing difficult without direct measurement of atrial signals.
Innovation Solution
Implementing a timer model with multiple timers to detect atrial events and trigger ventricular pacing based on timeouts, ensuring pacing synchrony even when atrial events are not detected, using a pair of electrodes to sense cardiac signals and process them through different amplification stages to identify atrial and ventricular events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a leadless pacemaker is used to avoid lead-related risks, then patient safety is improved, but the ability to reliably detect atrial events deteriorates due to small signal sizes and asynchronous activity
Solution Approach 1:
The patent segments the detection process into multiple specialized timers: a first timer for detecting atrial events with extended duration, a second timer for ventricular events, and a third timer for backup pacing. Each timer is optimized for specific signal characteristics, allowing the system to reliably detect both atrial and ventricular events despite the leadless configuration's signal limitations.
Solution Approach 2:
The system performs preliminary detection actions by continuously monitoring cardiac signals with multiple timers before making pacing decisions. The extended first timer proactively searches for atrial events in advance, and the backup third timer is prepared to ensure pacing continuity, allowing the system to maintain reliable VDD pacing without leads.
2Reliability
If multiple timers are used to detect atrial events and ensure pacing synchrony, then VDD pacing reliability is improved, but device complexity increases
Solution Approach 1:
The complex timing function is segmented into three distinct timers, each with specific responsibilities: the first timer detects atrial events with extended duration, the second timer handles ventricular events, and the third timer provides backup pacing. This segmentation makes the complex timing logic more manageable and reliable.
Solution Approach 2:
The multiple timers act as intermediary components that mediate between the raw cardiac signals and the pacing decision-making process. Each timer processes specific aspects of the cardiac cycle and provides structured timing information to the control logic, simplifying the overall decision-making process despite the increased number of components.
3Measurement precision
If the first timer duration is extended to improve atrial event detection, then detection sensitivity is improved, but the risk of oversensing increases
Solution Approach 1:
The detection process is segmented into multiple independent timers with different functions. The extended first timer focuses specifically on atrial event detection with high sensitivity, while the second timer independently monitors ventricular events. This segmentation allows each timer to be optimized for its specific detection task, reducing the risk of oversensing by distributing detection responsibilities.
Solution Approach 2:
The system uses feedback from multiple timers to verify detected events. The extended first timer's detection is cross-checked with the second timer's ventricular event detection and the overall cardiac cycle timing. This feedback mechanism allows the system to maintain high detection sensitivity while filtering out false positives through multi-timer verification.
Data Source
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AI summary
An implantable medical device (1) configured to provide for an intra-cardiac pacing comprises an electrode arrangement (11, 12) configured to sense a cardiac sense signal and a processing circuitry (15) operatively connected to the electrode arrangement (11, 12). The processing circuitry (15) is configured to start a first timer (20) based on a ventricular sense event (Vs); to open an atrial detection window (Tsense) based on a first timer count output by the first timer (20); to start a second timer (24) in case an atrial sense event (As) is identified using the cardiac sense signal after opening the atrial detection window (Tsense); to identify a first timeout (TO1) based on a comparison of a second timer count output by the second timer (24) and a first pacing delay (AVD) indicative of a delay after which a ventricular pace signal should be triggered following a prior atrial sense event (As); to identify a second timeout (TO2) based on a comparison of the first timer count output by the first timer (20) and a second pacing delay (VVD) indicative of a delay after which a ventricular pace signal should be triggered following a prior ventricular sense event (Vs) or ventricular pace event (Vp); to identify a third timeout (TO3) based on a comparison of the first timer count output by the first timer (20) and a basic rate interval (BRI) indicative of a longest allowable interval without a ventricular sense event (Vs) or ventricular pace event (Vp); and to trigger a ventricular pace signal based on an identification of at least one of the first timeout (TO1), the second timeout (TO2) and the third timeout (TO3).