IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
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출원번호 |
US-0368328
(2009-02-10)
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등록번호 |
US-8090434
(2012-01-03)
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발명자
/ 주소 |
- Lian, Jie
- Garner, Garth
- Muessig, Dirk
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출원인 / 주소 |
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
8 인용 특허 :
6 |
초록
▼
An implantable cardiac device, e.g., a pacemaker, defibrillator, cardioverter or biventricular pacing device, that can sense cardiac electrical signals and accurately classify the sensed events. The device provides a template signal and a test signal originated from an electrogram. The device furthe
An implantable cardiac device, e.g., a pacemaker, defibrillator, cardioverter or biventricular pacing device, that can sense cardiac electrical signals and accurately classify the sensed events. The device provides a template signal and a test signal originated from an electrogram. The device further transforms at least the test signal into a representation of the test signal for example in numerical format where the sample values of the test signal take the form of integers. The device further determines a correlation between the template and test signals, and classifies the sense events based on the correlation. The electrogram may be an intracardiac electrogram (IEGM), atrial electrogram (AEGM), ventricular electrogram (VEGM), surface electrocardiogram (ECG) or subcutaneous electrogram.
대표청구항
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1. A method for classifying sense events in implantable devices using signals provided by an electrogram comprising: providing a template signal and a test signal from an intracardiac electrogram IEGM signal,an atrial electrogram AEGM signal,a ventricular electrogram VEGM signal,a surface electrocar
1. A method for classifying sense events in implantable devices using signals provided by an electrogram comprising: providing a template signal and a test signal from an intracardiac electrogram IEGM signal,an atrial electrogram AEGM signal,a ventricular electrogram VEGM signal,a surface electrocardiogram ECG signal, ora subcutaneous electrogram signal,the template signal and the test signal comprising samples having sample values;constructing at least one of a normal atrial sense AS template waveform from the AEGM signal that corresponds to normal intrinsic atrial depolarization;a normal ventricular sense VS template waveform from the VEGM signal that corresponds to antegrade conducted ventricular depolarization;a retrograde AS template waveform from the AEGM signal that corresponds to retrograde atrial depolarization;a normal right ventricular RV sense template that corresponds to normal intrinsic RV depolarization;a normal left ventricular LV sense template that corresponds to normal intrinsic LV depolarization;transforming at least the test signal into a representation of the test signal wherein the sample values of the test signal are integers;determining a correlation between the template signal and the test signal;differentiating the retrograde atrial depolarization from normal intrinsic atrial depolarization via said correlation by calculating for an AS event detected within a post-ventricular atrial refractory period PVARP a first correlation value by comparing a corresponding AEGM signal with the normal atrial sense AS template waveform;depending on the first correlation value, indicating the AS event as a normal intrinsic AS, or not, then calculating a second correlation value by comparing the corresponding AEGM signal with the retrograde AS template waveform; and,depending on the second correlation value indicating the AS event as a retrograde AS, or neither the normal intrinsic AS, nor the retrograde AS; and,classifying a sense event based on the correlation. 2. The method according to claim 1, wherein constructing the normal atrial sense AS template waveform comprises using the AEGM signal corresponding to at least one AS event detected outside an atrial refractory period ARP;constructing the normal ventricular sense VS template waveform comprises using the VEGM signal corresponding to at least one VS event detected outside a ventricular refractory period VRP and is associated with at least one preceding AS event or at least one atrial pace AP event; and,constructing the retrograde AS template waveform comprises using the AEGM signal corresponding to at least one retrograde AS event. 3. The method according to claim 2, wherein the at least one retrograde AS event is confirmed by relatively stable intervals from ventricular paces VP to refractory atrial senses. 4. The method according to claim 1, wherein constructing each type of sense template waveform comprises: exposing the sense event;collecting multiple cycles of the IEGM signal containing the sense event;aligning the IEGM signal based on at least one predefined fiducial point; and,creating a sense template waveform by averaging similar aligned IEGM cycles. 5. The method according to claim 1, where said providing the template signal comprises obtaining the template signal by averaging a plurality of cycles of signals. 6. The method according to claim 1, further comprising updating the template signal periodically or continuously after an initial template setup. 7. The method according to claim 1, further comprising aligning the template signal and test signal based on at least one predefined fiducial point. 8. The method according to claim 1, further comprising: associating the template signal with at least two subspaces of template signal space; and,transforming at least one of the template signal and the test signal with respect to the at least two subspaces. 9. The method according to claim 8, wherein the at least two subspaces are defined by a first subspace comprising values which differ from template signal values at most by a predefined first value; and,a second subspace comprising values which differ from the template signal values at least by the predefined first value. 10. The method according to claim 8, wherein the at least two subspaces comprise three subspaces and the three subspaces are defined by a first subspace comprising values which differ from template signal values at most by a predefined first value,a second subspace comprising values which differ from template signal values at least by the predefined first value and at the most by a predefined second value; and,a third subspace comprising values which differ from the template signal values at least by the predefined second value. 11. The method according to claim 8, wherein the at least two subspaces are bounded by threshold vectors. 12. The method according to claim 11, wherein the threshold vectors are obtained by increasing or decreasing the sample values of the template signal by a predefined fixed value, or by a predefined ratio, or by a combination of the predefined fixed value and a predefined ratio. 13. The method according to claim 8, wherein said transforming comprises assigning a first, second or third integer to a sample of a transformed signal if a corresponding sample of the template signal and/or test signal belongs to a first, second or third subspace. 14. The method according to claim 13, where the first integer is 1, the second integer is 0 and the third integer is −1. 15. The method according to claim 1, wherein said determining the correlation is performed using at least a transformed test signal. 16. The method according to claim 15, wherein said determining the correlation is performed using only the transformed test signal. 17. The method according to claim 1, wherein said determining the correlation comprises using an adapted signed correlation index that is determined by summing the sample values of a transformed test signal or by dividing a sum of the sample values of the transformed test signal by a number of samples. 18. The method according to claim 1, further comprising detecting ectopic beat events by calculating the correlation between the template signal and the test signal. 19. The method according to claim 18, wherein said detecting ectopic beat events comprises: determining a correlation between a normal AS template and a test AEGM signal; and,depending on the correlation value, indicating a normal intrinsic AS event or an atrial extra-systole AES event. 20. The method according to claim 18, wherein said detecting ectopic beat events comprises: determining a correlation between a normal VS template and a test VEGM signal; and,depending on the correlation value, indicating a normal intrinsic VS template or an ventricular extra-systole VES event. 21. The method according to claim 18, wherein said detecting ectopic beat events comprises combining with at least one of a time interval analysis; and/or,signal processing algorithms for ectopic beat detection in devices or systems involving measurement and analysis of surface ECG signals. 22. The method according to claim 21, wherein said detecting ectopic beat events is only activated when the time interval analysis cannot definitely differentiate normal beat from ectopic beat. 23. The method according to claim 1, wherein said differentiating the retrograde atrial depolarization from normal intrinsic atrial depolarization further comprises combining with a time interval analysis. 24. The method according to claim 1, further comprising ignoring the AS event if the AS event is indicated as neither the normal intrinsic AS, nor the retrograde AS. 25. A method for classifying sense events in implantable devices using signals provided by an electrogram comprising: providing a template signal and a test signal, the template signal and the test signal comprising samples having sample values;transforming at least the test signal into a representation of the test signal wherein the sample values of the test signal are integers;determining a correlation between the template signal and the test signal;classifying a sense event based on the correlation;performing far field sensing classification with the correlation;calculating for an AS event detected within a far-field blanking FFB window a first correlation value by comparing a corresponding AEGM signal with a normal atrial sense AS template waveform;depending on the first correlation value, indicating the AS event as a normal intrinsic AS, or not, then further checking whether the AS event detected within the FFB is preceded by a VP or a VES event;depending on the result of the checking, calculating a second correlation value by comparing the corresponding AEGM signal with a retrograde AS template; anddepending on the second correlation value, indicating the AS event as a retrograde AS, or neither a normal intrinsic AS, nor a retrograde AS. 26. The method according to claim 25, wherein said performing said far field sensing classification comprises combining with a time interval analysis. 27. The method according to claim 25, where the AS event in FFB is ignored if the AS event is not preceded by the VP nor the VES event. 28. The method according to claim 25, where the AS event in FFB is ignored if the AS event is indicated as neither the normal intrinsic AS, nor the retrograde AS. 29. The method according to claim 25, further comprising: calculating a correlation value for an RV sense event detected within the FFB of a preceding LV event by comparing a corresponding RV IEGM with a normal RV sense template and depending on the correlation value, indicating the RV sense event as a normal intrinsic RV sense or a VES, a far-field sense, or a noise sense; and/or,calculating a correlation value for an LV sense event detected within the FFB of a preceding RV event by comparing a corresponding LV IEGM with a normal LV sense template and depending from the correlation value indicating the LV sense event as a normal intrinsic LV sense or the VES, the far-field sense, or the noise sense. 30. The method according to claim 29, wherein the RV sense event or the LV sense event in respective FFB is ignored if it is indicated as the VES, the far-field sense, or the noise sense. 31. A computer-readable storage medium comprising program code that causes a data processing device to classify sense events in implantable devices through use of signals obtained from an electrogram, wherein said program code is configured to: provide a template signal and a test signal, the template signal and the test signal comprising samples having sample values;transform at least the test signal into a representation of the test signal wherein the sample values of the test signal are integers;determine a correlation between the template signal and the test signal;perform far field sensing classification with the correlation;calculate for an AS event detected within a far-field blanking FFB window a first correlation value by comparison of a corresponding AEGM signal with a normal atrial sense AS template waveform;and depending on the first correlation value, indicate the AS event as a normal intrinsic AS, or not, then further check whether the AS event detected within the FFB is preceded by a VP or a VES event;and depending on the result of the check, calculate a second correlation value by comparison of the corresponding AEGM signal with a retrograde AS template;and depending on the second correlation value, indicate the AS event as a retrograde AS, or neither a normal intrinsic AS, nor a retrograde AS; and,classify a sense event based on the correlation.
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