Method and apparatus for verifying a determined cardiac event in a medical device based on detected variation in hemodynamic status
First Claim
1. A medical device comprising:
- a plurality of sensors configured to sense cardiac signals;
a physiologic sensor sensing physiologic signals configured to generate a plurality of oxygen (O2) variation index samples corresponding to the sensed signals; and
a microprocessor configured to;
detect a cardiac event in response to the sensed cardiac signals;
compute an O2 variation index trend associated with a predetermined number of O2 variation index samples of the plurality of O2 variation index samples in response to the detected cardiac event;
determine, in response to the O2 variation index trend being less than a variation index trend threshold, whether a rate of change of the O2 variation index trend is within a predetermined cardiac event zone defined by a first zone threshold having a first rate of change corresponding to the O2 variation index trend becoming less than the variation index trend threshold in a first period of time and a second zone threshold having a second rate of change corresponding to the O2 variation index trend becoming less than the variation index trend threshold in a second period of time greater than the first period of time;
and confirm the determined detected cardiac event in response to both the computed O2 variation index trend being less than the variation index trend threshold and the rate of change of the O2 variation index trend being within the predetermined cardiac event zone.
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Abstract
A method and apparatus for verifying a determined cardiac event in a medical device based on detected variation in hemodynamic status that includes a plurality of sensors sensing cardiac signals, and a physiologic sensor sensing physiologic signals to generate a plurality of variation index samples corresponding to the sensed signals. A microprocessor detects a cardiac event in response to the sensed cardiac signals, computes a variation index trend associated with a predetermined number of variation index samples of the plurality of variation index samples, determines a rate of change of the computed variation index trend, and confirms the determined cardiac event in response to the computed variation index trend and in response to the determined rate of change.
36 Citations
23 Claims
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1. A medical device comprising:
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a plurality of sensors configured to sense cardiac signals; a physiologic sensor sensing physiologic signals configured to generate a plurality of oxygen (O2) variation index samples corresponding to the sensed signals; and a microprocessor configured to; detect a cardiac event in response to the sensed cardiac signals; compute an O2 variation index trend associated with a predetermined number of O2 variation index samples of the plurality of O2 variation index samples in response to the detected cardiac event; determine, in response to the O2 variation index trend being less than a variation index trend threshold, whether a rate of change of the O2 variation index trend is within a predetermined cardiac event zone defined by a first zone threshold having a first rate of change corresponding to the O2 variation index trend becoming less than the variation index trend threshold in a first period of time and a second zone threshold having a second rate of change corresponding to the O2 variation index trend becoming less than the variation index trend threshold in a second period of time greater than the first period of time; and confirm the determined detected cardiac event in response to both the computed O2 variation index trend being less than the variation index trend threshold and the rate of change of the O2 variation index trend being within the predetermined cardiac event zone. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of determining a cardiac event in a medical device, comprising:
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sensing cardiac signals from a plurality of electrodes; detecting the cardiac event in response to the sensed cardiac signals; sensing physiologic signals and acquiring a plurality of O2 variation index samples corresponding to the sensed physiologic signals; computing an O2 variation index trend associated with a predetermined number of O2 variation index samples of the plurality of O2 variation index samples in response to detecting the cardiac event; determining, in response to the computed O2 variation index trend being less than a variation index trend threshold, whether a rate of change of the computed O2 variation index trend is within a predetermined cardiac event zone defined by a first zone threshold having a first rate of change corresponding to the O2 variation index trend becoming less than the variation index trend threshold in a first period of time, and a second zone threshold having a second rate of change corresponding to the O2 variation index trend becoming less than the variation index trend threshold in a second period of time greater than the first period of time; and confirming the determined detected cardiac event in response to both the computed O2 variation index trend being less than the variation index trend threshold and the rate of change of the O2 variation index trend being within the predetermined cardiac event zone. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A method of verifying a cardiac event in a medical device, comprising:
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sensing physiologic signals and acquiring a plurality of O2 variation index samples corresponding to the sensed physiological signals; computing an O2 variation index trend associated with a predetermined number of O2 variation index samples of the plurality of O2 variation index samples; determining whether a rate of change of the O2 variation index trend is within a predetermined cardiac event zone defined by a first zone threshold corresponding to a rate of change of O2 variation index samples associated with a non-physiologic event and a second zone threshold associated with a rate of change of O2 variation index samples associated with a sinus rhythm event; and verifying the cardiac event in response to the determined O2 variation index trend and the determining whether a rate of change is within a predetermined cardiac event zone. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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Specification