Pacemaker Mode Switching Safety Window Ventricular Discrimination
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Solution Overview
Problem
Existing active implantable medical devices, such as pacemakers, face issues with insufficient specificity in sensing ventricular disorders, leading to inappropriate mode commutations from AAI to DDD mode due to false detection of ventricular activity within the safety window, which can result in unnecessary prevention of spontaneous atrio-ventricular conduction.
Innovation Solution
The device introduces means to discriminate ventricular events during the safety window, associating specific markers with commutations not related to AV blocks and adapting the mode commutation algorithm to prevent inappropriate transitions to DDD mode by considering criteria such as shortening or lengthening of AV delay, and modifying the atrial escape interval or suspending atrial pacing to verify ventricular activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the device uses a safety window to ignore ventricular detections close to atrial pacing pulses, then false sensing of ventricular activity is reduced, but true ventricular activity during the safety window is also ignored leading to insufficient specificity in sensing ventricular disorders
Solution Approach 1:
The patent divides the safety window period into two segments: a first portion where ventricular detections are systematically ignored to prevent false sensing, and a second portion where ventricular detections are analyzed to identify true ventricular activity. This segmentation allows the device to distinguish between artifact-related signals and genuine ventricular events, resolving the contradiction between preventing false detections and maintaining detection specificity.
Solution Approach 2:
The patent applies different sensing criteria to different time periods within the safety window. During the first portion (close to atrial pacing), the device uses strict filtering to ignore detections, while during the second portion, it uses analytical criteria to identify true ventricular activity. This local differentiation of sensing quality allows the device to adapt its detection behavior to the specific temporal context, improving both false detection prevention and true activity identification.
2Reliability
If the device automatically commutes to DDD mode upon detecting ventricular activity during the safety window, then potential AV blocks are addressed, but inappropriate commutations occur due to false ventricular detections
Solution Approach 1:
The patent performs preliminary analysis of ventricular detections during the safety window before triggering mode commutation. By examining the characteristics of detected ventricular events and comparing them against established criteria during the second portion of the safety window, the device can preliminarily determine whether a true ventricular disorder exists before committing to a DDD mode commutation. This preliminary verification step prevents inappropriate commutations while maintaining a manageable commutation management strategy.
3Reliability
If the device ignores ventricular detections during the safety window, then sensing artifacts are prevented, but true ventricular activity is missed leading to unnecessary prevention of spontaneous AV conduction
Solution Approach 1:
The patent segments the safety window into two temporal portions with different detection strategies. The first portion systematically ignores detections to prevent artifact misinterpretation, while the second portion actively analyzes detections to identify true ventricular activity. This segmentation enables the device to preserve spontaneous AV conduction by not prematurely reacting to potential artifacts, while simultaneously maintaining the ability to detect true ventricular events that warrant attention.
Solution Approach 2:
The patent dynamically adjusts the device's detection and response behavior based on the temporal position within the safety window. During the first portion, the device adopts a conservative ignore strategy to prevent false reactions. During the second portion, it transitions to an active analysis mode to identify true ventricular activity. This dynamic adaptation of detection behavior allows the device to optimize both artifact rejection and true event detection at different stages of the safety window period.
Data Source
AI summary
An active implantable medical device of AAI/DDD type, notably a cardiac pacemaker, with improved management of mode commutation schemes in the presence of ventricular events of an uncertain nature. The device is able to pace the ventricle and the atrium; sense ventricular events (R, r), apply a safety window following an atrial pacing pulse; perform mode commutation, conditionally triggering commutation of the device from AAI to DDD mode; and diagnose atrio-ventricular conduction disorders determining the appearance of an atrio-ventricular block based upon a sequence of atrial events (A) not followed, during an atrial escape interval, by the detection of the corresponding ventricular event (R) out of the safety window. The device also is able to discriminate ventricular events, detect the occurrence of at least one ventricular event (r) during the safety window, in the absence of a detected atrio-ventricular block, and allowing to trace mode commutation or to inhibit mode commutation if certain conditions are fulfilled.