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US 2011/0257698 A1Published application
Method for exclusion of ectopic events from heart rate variability metrics
AssigneeCardiac Pacemakers, Inc.
InventorsJohn A. Dyjach, Gerrard M. Carlson
Life of this patent
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Abstract
Heart rate variability metrics are derived from the intervals between successive heart beats, referred to as BB intervals. A method implementable by an implantable cardiac device for excluding BB intervals due to ectopic beats based on a function of preceding BB intervals is presented. It is desirable to remove such BB intervals from a BB interval time series used to calculate a heart rate variability metric.
Claims20
A method for operating a cardiac device, comprising:
- sensing electrical activity in a cardiac chamber and generating a chamber sense signal when the sensed electrical activity exceeds a predetermined threshold;
- measuring time intervals between each pair of successive chamber senses, referred to as BB intervals, the measured BB intervals constituting a BB time series;
- filtering the BB intervals to exclude particular BB intervals as ectopic using a first-in-first-out buffer for storing a plurality of BB intervals by:
- 1) acquiring a present BB interval,
- 2) if the buffer contains less than N intervals, classifying the present BB interval as indeterminate, storing the indeterminately classified BB interval in the buffer, and returning to step 1,
- 3) if the buffer contains N intervals, computing a statistic from the stored BB intervals and comparing the present BB interval to the computed statistic,
- 4) excluding the present BB interval as an ectopic interval if the present BB interval is greater or less than the computed statistic by a specified threshold value, removing the oldest BB interval from the buffer, and returning to step 1,
- 5) updating the buffer by removing the oldest BB interval and storing the present BB interval therein if the present BB interval is not excluded as ectopic and then returning to step 1;
- and, computing a heart rate variability metric from the filtered BB intervals.
6 more elements
A cardiac rhythm management device, comprising:
- a sensing amplifier for sensing electrical activity in a cardiac chamber;
- a controller interfaced to the sensing channel which detects a chamber sense when the sensed electrical activity exceeds a predetermined threshold;
- wherein the controller is programmed with executable instructions for:
- measuring time intervals between each pair of successive chamber senses, referred to as BB intervals, the measured BB intervals constituting a BB time series;
- filtering the BB intervals to exclude particular BB intervals as ectopic using a first-in-first-out buffer for storing a plurality of previous BB intervals and from which a statistic is computed, where the buffer can contain a maximum number N of such preceding BB intervals, by:
- 1) acquiring a present BB interval,
- 2) if the buffer contains less than N intervals, classifying the present BB interval as indeterminate, storing the indeterminately classified BB interval in the buffer, and returning to step 1,
- 3) if the buffer contains N intervals, computing a statistic from the stored BB intervals and comparing the present BB interval to the computed statistic,
- 4) excluding the present BB interval as an ectopic interval if the present BB interval is greater or less than the computed statistic by a specified threshold value, removing the oldest BB interval from the buffer, and returning to step 1,
- 5) updating the buffer by removing the oldest BB interval and storing the present BB interval therein if the present BB interval is not excluded as ectopic and then returning to step 1;
- and,
- computing a heart rate variability metric from the filtered BB intervals.
9 more elements
Dependencies are inferred from the claim text.