Method and apparatus for identifying oversensing using far-field intracardiac electrograms and marker channels
First Claim
1. A method of detecting the occurrence of intrinsic depolarizations of a heart chamber comprising:
- obtaining a far-field electrogram (FF EGM) signal comprising a stream of digital sample points;
identifying possible intrinsic depolarizations by applying amplitude change criteria to subsets of the stream of digital sample points, the subsets comprising at least 3 digital sample points within the stream;
removing possible intrinsic depolarizations with amplitudes below an amplitude threshold criterion from further consideration as possible intrinsic depolarizations;
removing possible intrinsic depolarizations that occur within a blanking interval period immediately after a preceding intrinsic depolarization; and
marking the remaining possible intrinsic depolarizations as sensed events from the FF EGM signal.
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Accused Products
Abstract
A method for identifying and classifying various types of oversensing in implantable medical devices (IMDs), such as implantable cardioverter defibrillators (ICDs), to assist a physician in choosing corrective action to reduce the likelihood of oversensing and inappropriate therapy delivery. Far-field electrogram (EGM) signals are analyzed to detect the occurrence of R-waves, and the result is compared to the number and pattern of R-waves sensed by the IMD and indicated on the marker channel. A marker channel with more sensed R-waves than indicated by analysis of the far-field EGM indicates the presence of oversensing, including double-counting of R-waves, T-wave oversensing, lead malfunction or failure, poor lead connections, noise associated with electromagnetic interference, non-cardiac myopotentials, etc. Identification of the type of oversensing may be determined by analysis of the number and pattern of marker channel sensed R-waves with respect to the timing of the R-waves detected from the far-field EGM.
147 Citations
20 Claims
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1. A method of detecting the occurrence of intrinsic depolarizations of a heart chamber comprising:
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obtaining a far-field electrogram (FF EGM) signal comprising a stream of digital sample points;
identifying possible intrinsic depolarizations by applying amplitude change criteria to subsets of the stream of digital sample points, the subsets comprising at least 3 digital sample points within the stream;
removing possible intrinsic depolarizations with amplitudes below an amplitude threshold criterion from further consideration as possible intrinsic depolarizations;
removing possible intrinsic depolarizations that occur within a blanking interval period immediately after a preceding intrinsic depolarization; and
marking the remaining possible intrinsic depolarizations as sensed events from the FF EGM signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of detecting the occurrence of intrinsic depolarizations of a heart chamber comprising:
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obtaining a far-field electrogram (FF EGM) signal comprising a stream of digital sample points;
generating a derivative signal from the FF EGM;
identifying patterns in the derivative signal that indicate a peak in the FF EGM signal;
removing identified patterns in the derivative signal having magnitudes that do not meet minimum slope criteria from further analysis;
identifying possible intrinsic depolarizations as occurring near polarity change points in the remaining identified patterns of the derivative signal;
removing possible intrinsic depolarizations having corresponding FF EGM amplitude values below an amplitude threshold criterion from further consideration as possible intrinsic depolarizations;
removing possible intrinsic depolarizations that occur within a blanking period immediately after a preceding intrinsic depolarization from further consideration as possible intrinsic depolarizations; and
marking the remaining possible intrinsic depolarizations as sensed events from the FF EGM signal. - View Dependent Claims (11, 12, 13, 14)
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15. A method of identifying oversensing of cardiac R-waves by an implantable medical device (IMD), comprising:
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detecting intrinsic R-waves from a near-field electrogram (NF EGM) signal and defining such detected R-waves as VS-NF events;
detecting intrinsic R-waves from a far-field electrogram (FF EGM) signal and defining such detected R-waves as VS-FF events;
comparing the VS-FF events to the VS-NF events to determine which VS-NF events have a corresponding VS-FF event, and defining such VS-NF events as mapped VS-NF events;
comparing the VS-FF events to the VS-NF events to determine which VS-NF events do not have a corresponding VS-FF event and defining such VS-NF events an unmapped VS-NF events;
determining whether unmapped VS-NF events exceed mapped VS-NF events by a predetermined amount to indicate the presence of oversensing; and
classifying the type of oversensing as being one of lead failure/fracture/connection, T-wave oversensing, R-wave double counting, and other type of oversensing after the presence of oversensing is indicated, the lead failure type of oversensing being indicated by the presence of more than a predetermined number of unmapped VS-NF events between a predetermined number of mapped VS-NF events, the T-wave type of oversensing being indicated by the presence of alternating morphologies, the R-wave double-counting type of oversensing being indicated by the presence of a short-long interval pattern, and the other type of oversensing being indicated when none of lead failure, T-wave oversensing, and R-wave double counting are indicated. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification