IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
US-0189386
(2011-07-22)
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등록번호 |
US-8185198
(2012-05-22)
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발명자
/ 주소 |
- Palreddy, Surekha
- Warren, Jay A.
- Phillips, James W.
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출원인 / 주소 |
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
13 인용 특허 :
2 |
초록
▼
Implementations of various technologies described herein are directed toward a sensing architecture for use in cardiac rhythm management devices. The sensing architecture may provide a method and means for certifying detected events by the cardiac rhythm management device. Moreover, by exploiting th
Implementations of various technologies described herein are directed toward a sensing architecture for use in cardiac rhythm management devices. The sensing architecture may provide a method and means for certifying detected events by the cardiac rhythm management device. Moreover, by exploiting the enhanced capability to accurately identifying only those sensed events that are desirable, and preventing the use of events marked as suspect, the sensing architecture can better discriminate between rhythms appropriate for device therapy and those that are not.
대표청구항
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1. A method of identifying treatable cardiac conditions in an implantable cardiac stimulus device (ICSD), the ICSD comprising a plurality of electrodes for implantation in a patient and operational circuitry electrically coupled to the electrodes and configured to perform analysis of cardiac signals
1. A method of identifying treatable cardiac conditions in an implantable cardiac stimulus device (ICSD), the ICSD comprising a plurality of electrodes for implantation in a patient and operational circuitry electrically coupled to the electrodes and configured to perform analysis of cardiac signals to identify malignant conditions, the method comprising: monitoring a signal captured between the electrodes;observing a plurality of events in the monitored signal;performing waveform appraisal on each observed event;certifying at least some of the observed events for use in event classification;marking at least one of the observed events as a suspect event, such that all events are either certified or marked as suspect;performing event classification using the certified observed events to determine whether the certified observed events suggest a need for cardiac electrical therapy to generate a number of classification outcomes;tracking classification outcomes using an X-out-of-Y counter; anddetermining whether the X-out-of-Y counter exceeds a threshold and, if so, declaring a malignant condition;wherein the X-out-of-Y counter uses only certified observed events, and any suspect events are excluded from the X-out-of-Y counter, such that the at least one observed event that is marked as a suspect event is not counted in either X or Y of the X-out-of-Y counter. 2. The method of claim 1 wherein the step of performing waveform appraisal on each observed event includes: gathering a signal corresponding to and including the observed event in an analysis window;observing characteristic features of the slope of the signal in the analysis window;counting the characteristic features to determine the quantity of the characteristic features that occur during the analysis window; andcomparing the quantity of the characteristic features that occur in the analysis window to a threshold. 3. The method of claim 2 wherein: the step of counting the characteristic features includes identifying an integer value equal to how many of the characteristic features there are in the signal; andthe step of comparing the quantity of the characteristic features to a threshold includes comparing the integer value to the threshold. 4. A method of identifying treatable cardiac conditions in an implantable cardiac stimulus device (ICSD), the ICSD comprising a plurality of electrodes for implantation in a patient and operational circuitry electrically coupled to the electrodes and configured to perform analysis of cardiac signals to identify malignant conditions, the method comprising: monitoring a signal captured between the electrodes;observing a plurality of events in the monitored signal;performing waveform appraisal on each observed event;certifying at least some of the observed events for use in event classification;marking at least one of the observed events as a suspect event, such that all events are either certified or marked as suspect;performing event classification using the certified observed events to determine whether the certified observed events suggest a need for cardiac electrical therapy to generate a number of classification outcomes;tracking classification outcomes using an X-out-of-Y counter;determining whether the X-out-of-Y counter exceeds a threshold and, if so, declaring a malignant condition;wherein the X-out-of-Y counter uses only certified observed events, and any suspect events are excluded from the X-out-of-Y counter, wherein the step of observing characteristic features includes identifying a number of points in the signal where the signal slope reaches a local maximum magnitude, representing zero crossings of the second derivative of the signal; andwherein the step of performing waveform appraisal on each observed event includes:gathering a signal corresponding to and including the observed event in an analysis window;observing characteristic features of the slope of the signal in the analysis window;counting the characteristic features to determine the quantity of the characteristic features that occur during the analysis window; andcomparing the quantity of the characteristic features that occur in the analysis window to a threshold. 5. The method of claim 4 wherein the steps of certifying and marking are performed as follows: if the quantity of the characteristic features exceeds the threshold for a particular observed event, that particular observed event is marked as a suspect event; andotherwise, the particular observed event is certified. 6. The method of claim 4 wherein the steps of certifying and marking are performed as follows: if the quantity of the characteristic features is less than the threshold for a particular observed event, that particular observed event is certified; andotherwise, the particular observed event is marked as suspect. 7. The method of claim 4 wherein the step of observing characteristic features includes: selecting a first zero crossing of the second derivative as a significant maximum slope point; andcharacterizing subsequent zero crossings of the second derivative as either significant maximum slope points or not significant maximum slope points;wherein the significant maximum slope points are observed to be the characteristic features. 8. The method of claim 7 wherein the step of characterizing subsequent zero crossings of the second derivative includes determining whether the path length from a most recent significant maximum slope point to the zero crossing of the second derivative under consideration exceeds a path length threshold, and: if so, finding the zero crossing of the second derivative under consideration to be a significant maximum slope point;if not, ignoring the zero crossing of the second derivative under consideration. 9. The method of claim 8, wherein the path length threshold is related to a selected percentage of the maximum signal amplitude for the observed event. 10. The method of claim 7, wherein the step of characterizing subsequent zero crossings of the second derivative includes determining whether the path length from a most recent significant maximum slope point to the zero crossing of the second derivative under consideration exceeds the magnitude of the difference in amplitude between: the signal at the time of the most recent significant maximum slope point; andthe signal at the time of the zero crossing of the second derivative under consideration. 11. The method of claim 7, wherein the step of characterizing subsequent zero crossings of the second derivative includes analysis using a first rule and a second rule, wherein: the first rule calls for determining whether the path length from a most recent significant maximum slope point to the zero crossing of the second derivative under consideration exceeds a path length threshold; andthe second rule calls for determining whether the path length from a most recent significant maximum slope point to the zero crossing of the second derivative under consideration exceeds the magnitude of the difference in amplitude between:the signal at the time of the most recent significant maximum slope point; andthe signal at the time of the zero crossing of the second derivative under consideration. 12. The method of claim 2 wherein: the step of observing characteristic features of the slope of the signal includes: sampling the signal to generate a set of samples; anddividing the sampled signal into divisions each including a plurality of the samples;the step of counting the characteristics features includes counting how many of the divisions are monotonic to yield a number M; andthe step of comparing the quantity of the characteristic features to the threshold includes comparing M to the threshold. 13. An implantable cardioverter/defibrillator (ICD) comprising: a lead electrode assembly including a number of electrodes; anda canister housing operational circuitry; wherein:the lead electrode assembly is configured for coupling to the canister; andthe operational circuitry is configured to:monitor a signal captured between the electrodes;observe a plurality of events in the monitored signal;perform waveform appraisal on each observed event;certify at least some of the observed events for use in event classification;mark at least one observed events as a suspect event, such that all events are either certified or marked as suspect;perform event classification using the certified observed events to determine whether the certified observed events suggest a need for cardiac electrical therapy to generate a number of classification outcomes;track classification outcomes using an X-out-of-Y counter; anddetermine whether the X-out-of-Y counter exceeds a threshold and, if so, declaring a malignant condition;wherein the X-out-of-Y counter uses only certified observed events, and any suspect events are excluded from the X-out-of-Y counter, such that the at least one observed event that is marked as a suspect event is not counted in either X or Y of the X-out-of-Y counter. 14. The ICSD of claim 13 wherein the operational circuitry is configured such that waveform appraisal includes: gathering a signal corresponding to and including the observed event in an analysis window;observing characteristic features of the slope of the signal in the analysis window;counting the characteristic features to determine the quantity of the characteristic features that occur during the analysis window; andcomparing the quantity of the characteristic features that occur in the analysis window to a threshold. 15. The ICSD of claim 14 wherein the operational circuitry is configured such that, in waveform appraisal, observing characteristic features includes identifying a number of points in the signal where the signal slope reaches a local maximum magnitude, representing zero crossings of the second derivative of the signal, and the operational circuitry is further configured such that: if the quantity of the characteristic features exceeds the threshold for a particular observed event, that particular observed event will be marked as a suspect event; andotherwise, the particular observed event will be certified. 16. The ICSD of claim 14 wherein the operational circuitry is configured such that, in waveform appraisal, observing characteristic features includes identifying a number of points in the signal where the signal slope reaches a local maximum magnitude, representing zero crossings of the second derivative of the signal, and the operational circuitry is further configured such that: if the quantity of the characteristic features is less than the threshold for a particular observed event, that particular observed event is certified; andotherwise, the particular event is marked as suspect. 17. The ICSD of claim 14 wherein the operational circuitry is configured such that, in waveform appraisal, observing characteristic features includes: selecting a first zero crossing of the second derivative as a significant maximum slope point; andcharacterizing subsequent zero crossings of the second derivative as either significant maximum slope points or not significant maximum slope points;wherein the significant maximum slope points will identified as the characteristic features. 18. The ICSD of claim 17 wherein the operational circuitry is configured such that, in waveform appraisal, characterizing subsequent zero crossings of the second derivative includes determining whether the path length from a most recent significant maximum slope point to the zero crossing of the second derivative under consideration exceeds a path length threshold, and: if so, finding the zero crossing of the second derivative under consideration to be a significant maximum slope point;if not, ignoring the zero crossing of the second derivative under consideration. 19. The ICSD of claim 18, wherein the operational circuitry is configured such that, in waveform appraisal, the path length threshold is a selected percentage of the maximum signal amplitude for the observed event. 20. The ICSD of claim 17, wherein the operational circuitry is configured such that, in waveform appraisal, characterizing subsequent zero crossings of the second derivative includes determining whether the path length from a most recent significant maximum slope point to the zero crossing of the second derivative under consideration exceeds the magnitude of the difference in amplitude between: the signal at the time of the most recent significant maximum slope point; andthe signal at the time of the zero crossing of the second derivative under consideration. 21. The ICSD of claim 17, wherein the operational circuitry is configured such that, in waveform appraisal, characterizing subsequent zero crossings of the second derivative includes analysis using a first rule and a second rule, and: the first rule calls for determining whether the path length from a most recent significant maximum slope point to the zero crossing of the second derivative under consideration exceeds a path length threshold; andthe second rule calls for determining whether the path length from a most recent significant maximum slope point to the zero crossing of the second derivative under consideration exceeds the magnitude of the difference in amplitude between:the signal at the time of the most recent significant maximum slope point; andthe signal at the time of the zero crossing of the second derivative under consideration. 22. The ICSD of claim 14 wherein the operational circuitry is configured such that, in waveform appraisal: observing characteristic features of the slope of the signal includes sampling the signal to generate a set of samples and dividing the sampled signal into divisions each including a plurality of the samples;counting the characteristics features includes counting how many of the divisions are monotonic to yield a number M; andcomparing the quantity of the characteristic features to the threshold includes comparing M to the threshold.
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