IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
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출원번호 |
US-0441522
(2006-05-26)
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등록번호 |
US-8788023
(2014-07-22)
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발명자
/ 주소 |
- Sanghera, Rick
- Allavatam, Venugopal
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출원인 / 주소 |
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대리인 / 주소 |
Schwegman, Lundberg & Woessner, P.A.
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인용정보 |
피인용 횟수 :
17 인용 특허 :
197 |
초록
▼
Methods and devices for sensing vector analysis in an implantable cardiac stimulus system. In an illustrative example, a first sensing vector is analyzed to determine whether it is suitable, within given threshold conditions, for use in cardiac event detection and analysis. If so, the first vector m
Methods and devices for sensing vector analysis in an implantable cardiac stimulus system. In an illustrative example, a first sensing vector is analyzed to determine whether it is suitable, within given threshold conditions, for use in cardiac event detection and analysis. If so, the first vector may be selected for detection and analysis. Otherwise, one or more additional vectors are analyzed. A detailed example illustrates methods for analyzing sensing vectors by the use of a scoring system. Additional examples include implantable devices, implantable device systems, and/or programmers for use in conjunction with implantable devices, each configured to perform such methods.
대표청구항
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1. A method for use with an implantable medical system comprising an implantable medical device (IMD) adapted to define a plurality of sensing vectors between electrodes implanted in a patient for capturing cardiac signals, and a programmer adapted for communication with the IMD; the method comprisi
1. A method for use with an implantable medical system comprising an implantable medical device (IMD) adapted to define a plurality of sensing vectors between electrodes implanted in a patient for capturing cardiac signals, and a programmer adapted for communication with the IMD; the method comprising: the IMD capturing cardiac signal data from at least one of the plurality of sensing vectors;the IMD analyzing data related to the captured cardiac signal data for vector selection purposes and either: determining that an identified sensing vector is suitable for cardiac event detection; ordetermining that one or more further sensing vectors is to be analyzed;wherein the step of the IMD analyzing data related to the captured cardiac signal data for vector selection purposes is performed by:the IMD setting a detection threshold and identifying a set of detected events separated by intervals in the cardiac signal data;the IMD analyzing the set of detected events and intervals and characterizing the detected events as either Noise or QRS, including, for at least a given one of the detected events, observing that two intervals, namely an interval before the given event and an interval before a preceding event occurring just before the given event, are very similar and shorter than a predetermined threshold and in response to the intervals being very similar, performing amplitude analysis to characterize the given event and the preceding event as either Noise or QRS, wherein if amplitude analysis is reached, the result is limited to either: i) characterizing the given event as Noise and the preceding event as QRS; orii) characterizing the given event as QRS and the preceding event as Noise,further wherein, in the step of analyzing and characterizing, if two intervals are equal, the two intervals are considered very similar. 2. The method of claim 1, wherein, if it is determined that one or more sensing vectors is to be analyzed, the method further comprises: capturing additional cardiac signal data from one or more other sensing vectors using the IMD;the IMD analyzing data related to the captured additional cardiac signal data and: determining that an identified sensing vector is suitable for cardiac event detection;determining that there is a best available sensing vector; orthe IMD communicating a message to the programmer to request that the programmer request operator input to complete a sensing vector selection process. 3. The method of claim 2, wherein the IMD performs the capturing, analyzing and determining steps periodically. 4. The method of claim 2, wherein the IMD performs the capturing, analyzing and determining steps occasionally. 5. The method of claim 2, wherein the IMD performs the capturing, analyzing and determining steps in response to a request from the programmer. 6. The method of claim 1, wherein the IMD includes signal processing circuitry having at least a selectable first dynamic range and a selectable second dynamic range, the dynamic ranges accommodating different cardiac signal amplitudes, wherein, if the identified sensing vector is suitable for cardiac event detection, a dynamic range is selected. 7. The method of claim 1 wherein the step of setting a detection threshold comprises: selecting an initial level for a preliminary detection threshold;next iteratively comparing the cardiac signal data to the preliminary detection threshold and if the cardiac signal data crosses the preliminary detection threshold, raising the preliminary detection threshold upward from the initial level until it reaches a level at which a timeout occurs with no crossing of the preliminary detection threshold by the cardiac signal data; andsetting the detection threshold to a percentage of the level of the preliminary detection threshold at which the timeout occurs. 8. A programmer for use with an implantable medical device (IMD), the IMD including or configured for attachment to electrodes for sensing cardiac signals, the programmer comprising telemetry circuitry for communicating with the IMD, a user interface for communicating with an operator, and operational circuitry configured to perform a method of selecting a sensing vector for the IMD, the method which the programmer is configured to perform comprising: X) directing the IMD to capture and transmit data related to a selected sensing vector, including the IMD identifying a set of detected events separated by intervals in the data from the selected sensing vector;Y) analyzing the transmitted data to determine if the selected sensing vector is well-suited for cardiac event detection; and: if the selected sensing vector is well suited for cardiac event detection, directing the IMD to use the selected sensing vector for cardiac event detection; orrepeating X) and Y) with another sensing vector;wherein analyzing the transmitted data to determine if the selected sensing vector is well-suited is performed while the patient is experiencing a cardiac rate in a range having an upper limit and comprises: analyzing the set of detected events and the intervals separating the detected events and characterizing events as either Noise or QRS by:a) observing the interval before a given event and, if the interval is greater than a predetermined length, wherein the predetermined length is set to correspond to the upper limit of the cardiac rate range, characterizing the given event as QRS; otherwise,b) observing whether the interval before the given event and the interval before a preceding event are very similar and, if so, performing amplitude analysis to characterize the given event and the preceding event as either Noise or QRS; andc) if neither a) nor b) determining whether to characterize the given event as Noise or QRS by comparing the interval before the given event to the interval before the preceding event, and characterizing the given event as noise if the interval before the given event is the shorter of the two intervals:further wherein, if amplitude analysis is performed, either:i) the given event is characterized as Noise and the preceding event is characterized as QRS; orii) the given event is characterized as QRS and the preceding event is characterized as Noise;further wherein, in b), if two intervals are equal, the two intervals are considered very similar. 9. The programmer of claim 8, wherein the operational circuitry is further configured to perform the steps of: if repetition of steps X) and Y) does not yield a sensing vector well suited for cardiac event detection, identifying the best of the sensing vectors and directing the implantable medical device system to use the best sensing vector for cardiac event detection. 10. The programmer of claim 9, wherein the operational circuitry includes an input amplifier for amplifying captured signals, the input amplifier having more than one selectable dynamic range to accommodate differing cardiac signal amplitudes, wherein the operational circuitry is further configured to perform the steps of identifying an appropriate input amplifier dynamic range for the IMD and directing the IMD system to use the identified dynamic range. 11. The programmer of claim 9, wherein the operational circuitry is adapted such that: steps X) and Y) allow for determination of at least an actual score or multiple possible scores, the multiple possible scores being determined when analysis reveals a likely ambiguity, each possible score corresponding to an outcome of the ambiguity; andthe step of identifying the best of the sensing vectors, when performed, comprises: identifying a set of available scores including any scores and possible scores determined when steps X) and Y) were performed;selecting a best available score from the set of available scores and:if the best available score is an actual score, identifying a corresponding sensing vector as the best of the sensing vectors;if the best available score is a possible score, requesting user input to eliminate the likely ambiguity, determining whether the user input verifies an outcome corresponding to the possible score and, if so, identifying a corresponding sensing vector as the best of the sensing vectors, or, if not, removing the possible score from the set of available scores and returning to the step of selecting a best available score from the set of available scores. 12. The programmer of claim 11, wherein the operational circuitry is adapted such that: X) and Y) also allow for a determination that a vector is unsuitable for cardiac event detection, and, if a particular vector is determined to be unsuitable for cardiac event detection, that vector is not considered in the step of identifying the best of the sensing vectors. 13. The programmer of claim 8, wherein the operational circuitry is adapted such that steps X) and Y) include calculating either a score or, if ambiguity is likely, multiple possible scores for the selected sensing vector and the selected sensing vector is well-suited for cardiac event detection if a score is calculated and the score exceeds a threshold for the selected sensing vector. 14. The programmer of claim 8, wherein the operational circuitry comprises readable memory encoding an instruction set for performing the method of selecting a sensing vector for the IMD. 15. An implantable medical device (IMD) including or configured for coupling to electrodes for sensing cardiac signals and operational circuitry coupled to the electrodes, the IMD adapted to define a plurality of sensing vectors for observing electrical activity of a patient's heart from implanted positions, the operational circuitry configured to perform a method of selecting a sensing vector for the IMD, the method comprising: X) capturing data related to a selected sensing vector;Y) analyzing the captured data for vector selection purposes to determine if the selected sensing vector is well-suited for cardiac event detection;if the selected sensing vector is well suited for cardiac event detection, using the selected sensing vector for cardiac event detection; orrepeating X) and Y) with another sensing vector;wherein analyzing data related to the captured cardiac signal data for vector selection purposes is performed while the patient is experiencing a cardiac rate in a range having an upper limit and comprises:setting a detection threshold and identifying a set of events separated by intervals in the cardiac signal data;analyzing the set of events and characterizing events as either Noise or QRS by:a) observing the interval before a given event and, if the interval is greater than a predetermined length, characterizing the given event as QRS, the predetermined length being set to correspond to the upper limit of the cardiac rate range; otherwise,b) observing whether the interval before the given event and the interval before a preceding event are very similar and, if so, performing amplitude analysis to characterize the event and the preceding event as either Noise or QRS; andc) if neither a) nor b), determining whether to characterize the given event as Noise or QRS by comparing the interval before the given event to the interval before the preceding event to identify the shorter of the two intervals, and identifying the given event as Noise if the interval before the given event is the shorter of the two intervals:further wherein, if amplitude analysis is performed, either:i) the given event is characterized as Noise and the preceding event is characterized as QRS; orii) the given event is characterized as QRS and the preceding event is characterized as Noise; still further wherein, in b), if the two intervals are equal, then the two intervals are observed to be very similar. 16. The IMD of claim 15, wherein the operational circuitry is further configured to perform the steps of: if a second sensing vector is well suited for cardiac event detection, using the second sensing vector for cardiac event detection; orrepeating steps X) and Y) with a yet another sensing vector; andif a third sensing vector is well suited for cardiac event detection, using the third sensing vector for cardiac event detection; oridentifying the best of the sensing vectors and using the best sensing vector for cardiac event detection. 17. The IMD of claim 16, further comprising telemetry circuitry for communicating with a programmer having a user interface, wherein the operational circuitry is adapted such that: steps X) and Y) allow for determination of at least an actual score or multiple possible scores, the multiple possible scores being determined when analysis reveals a likely ambiguity, each possible score corresponding to an outcome of the ambiguity; andthe step of identifying the best sensing vector, when performed, includes: identifying a set of available scores including any scores and possible scores determined when steps X) and Y) were performed;selecting a best available score from the set of available scores and:if the best available score is an actual score, identifying a corresponding sensing vector as the best of the sensing vectors;if the best available score is a possible score, using the telemetry circuitry to direct the programmer to request user input to eliminate the likely ambiguity, receiving a response from the programmer indicating the user input, determining whether the user input verifies an outcome corresponding to the possible score and, if so, identifying a corresponding sensing vector as the best of the sensing vectors, or, if not, removing the possible score from the set of available scores and returning to the step of selecting a best available score from the set of available scores. 18. The IMD of claim 17, wherein the operational circuitry is adapted such that: steps X) and Y) also allow for a determination that a vector is unsuitable for cardiac event detection, and, if a particular vector is determined to be unsuitable for cardiac event detection, that vector is not considered in step a). 19. The IMD of claim 15, wherein the operational circuitry is adapted such that steps X) and Y) include calculating either a score or, if ambiguity is likely, multiple possible scores for the selected sensing vector and the selected sensing vector is well-suited for cardiac event detection if a score is calculated and the score exceeds a threshold for the selected sensing vector. 20. The IMD of claim 19, wherein the operational circuitry is adapted such that, if steps X) and Y) are repeated for multiple sensing vectors, the threshold is adapted to each of the sensing vectors. 21. The IMD of claim 15, wherein the operational circuitry comprises readable memory encoding an instruction set for performing the method of selecting a sensing vector. 22. The IMD of claim 15 wherein the operational circuitry is configured such that the step of setting a detection threshold comprises: selecting an initial level for a preliminary detection threshold;next iteratively comparing the cardiac signal data to the preliminary detection threshold and if the cardiac signal data crosses the preliminary detection threshold, raising the preliminary detection threshold upward from the initial level until it reaches a level at which a timeout occurs with no crossing of the preliminary detection threshold by the cardiac signal data; andsetting the detection threshold to a percentage of the level of the preliminary detection threshold at which the timeout occurs.
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