Method for adapting charge initiation for an implantable cardioverter-defibrillator
First Claim
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1. A method of cardiac signal analysis in an implantable cardiac stimulus device comprising electrodes configured for implantation in a patient, the method comprising:
- capturing a signal from the electrodes;
detecting, using analysis of the captured signal, a series of detected events; and
determining whether a malignant arrhythmia appears likely by;
a) using an X/Y counter having an indication of likely malignant events (X) out of a set of detected events (Y); and
b) comparing the X/Y counter to a predetermined counter ratio; and
wherein the method also comprises the implantable device selecting the predetermined counter ratio using the following rules;
c) if nonsustained high rate event conditions have not been previously detected, a first counter ratio is selected; and
d) if nonsustained high-rate event conditions have been previously identified, a second counter ratio is selected, wherein the selection of the second counter ratio remains in place for use in identifying future malignant arrhythmias and avoiding unnecessary treatment of future nonsustained high rate event conditions.
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Abstract
Adaptive methods for initiating charging of the high power capacitors of an implantable medical device for therapy delivery after the patient experiences a non-sustained arrhythmia. The adaptive methods adjust persistence criteria used to analyze an arrhythmia prior to initiating a charging sequence to deliver therapy.
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Citations
24 Claims
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1. A method of cardiac signal analysis in an implantable cardiac stimulus device comprising electrodes configured for implantation in a patient, the method comprising:
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capturing a signal from the electrodes; detecting, using analysis of the captured signal, a series of detected events; and determining whether a malignant arrhythmia appears likely by; a) using an X/Y counter having an indication of likely malignant events (X) out of a set of detected events (Y); and b) comparing the X/Y counter to a predetermined counter ratio; and wherein the method also comprises the implantable device selecting the predetermined counter ratio using the following rules; c) if nonsustained high rate event conditions have not been previously detected, a first counter ratio is selected; and d) if nonsustained high-rate event conditions have been previously identified, a second counter ratio is selected, wherein the selection of the second counter ratio remains in place for use in identifying future malignant arrhythmias and avoiding unnecessary treatment of future nonsustained high rate event conditions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of cardiac signal analysis in an implantable cardiac stimulus device, the device comprising electrodes configured for implantation in a patient and telemetry circuitry allowing an operator to program parameters used in the device to determine whether to deliver therapy, the method comprising:
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capturing a signal from the electrodes; detecting, by analysis of the signal, detected events in the signal; and determining whether a malignant arrhythmia appears likely by; a) using an X/Y counter having an indication of likely malignant events (X) out of a set of detected events (Y); b) comparing the X/Y counter to a predetermined counter ratio; and c) if the X/Y counter exceeds the predetermined ratio, determining whether the X/Y counter has exceeded the predetermined ratio at least N times and, if so, determining that a malignant arrhythmia appears likely; wherein N is automatically predetermined by the implantable device such that N has an initial value and, following identification of nonsustained apparently malignant conditions, N is increased to a higher value than the initial value and remains at the higher value for use in subsequent event processing to identify future malignant arrhythmias and avoid treatment for future nonsustained high-rate condtiions. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. An implantable cardiac stimulus device comprising:
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a canister containing a battery, charging circuitry, energy storage circuitry, control circuitry, and coupling circuitry, in which the control circuitry controls operation and use of the charger, energy storage and coupling circuitry to provide cardiac signal monitoring and, when indicated, cardiac therapy; and a plurality of electrodes connected to the coupling circuitry which, in turn, couples the control circuitry to the plurality of electrodes to allow cardiac signal monitoring and, when indicated, cardiac therapy; wherein the control circuitry is configured to perform the following method; capturing cardiac signals from the electrodes via the coupling circuitry when implanted in a patient to detect the patient'"'"'s cardiac condition; determining from captured signals whether a likely arrhythmia is occurring; and
,if a likely arrhythmia is occurring; determining whether the device has previously identified indication(s) of nonsustained tachyarrhythmia(s); selecting between a first X/Y counter ratio and a second X/Y counter ratio for use in determining whether cardiac stimulus is indicated by using at least a step of determining whether previous nonsustained tachyarrhythmia(s) have occurred; applying the selected X/Y counter ratio to determine whether cardiac stimulus is indicated; further wherein, if previous nonsustained tachyarrhythmia(s) have been detected, the selection between the first and second X/Y counter ratios reduces the likelihood that a new nonsustained tachyarrythmia could lead to therapy delivery by the device. - View Dependent Claims (18, 19, 20, 21)
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22. An implantable cardiac stimulus device configured for implantation into a patient'"'"'s body comprising a housing, operational circuitry contained in the housing, and a number of electrodes coupled to the operational circuitry and disposed either on the housing, as part of the housing, or on one or more leads coupled to the housing, wherein the operational circuitry is configured to perform a method of cardiac signal analysis comprising:
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capturing signals from the electrodes when implanted in a patient; identifying detected events in the captured signals with the intent that detected events represent cardiac events; determining whether a high-rate arrhythmia appears likely; if so, analyzing detected events to identify those which likely indicate a malignant cardiac rhythm; and determining whether an X/Y counter in which X represents the number of detected events identified as likely indicating a malignant cardiac rhythm out of a set of Y detected events indicates therapy for the patient; wherein the operational circuitry is configured to identify nonsustained tachycardia and, if nonsustained tachycardia is identified, to determine whether to modify the X/Y counter to use a larger sample size and the larger sample size is used for future cardiac signal analysis to avoid therapy on future nonsustained tachycardia.
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23. An implantable cardiac stimulus device comprising an implantable canister and a plurality of electrodes, the canister containing operational circuitry configured to perform cardiac signal captured and analysis, as well as defibrillation circuitry configured to provide defibrillation therapy if indicated by analysis of cardiac signal, the operational circuitry further configured to perform a method of cardiac signal analysis comprising:
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capturing a signal from the electrodes when implanted in a patient; detecting, using analysis of the captured signal, a series of detected events; and determining whether a malignant arrhythmia appears likely by; a) using an X/Y counter having an indication of likely malignant events (X) out of a set of detected events (Y); b) comparing the X/Y counter to a predetermined counter ratio; and c) if the X/Y counter exceeds the predetermined counter ratio, determining whether the predetermined counter ratio is exceeded by the X/Y counter for at least N iterations and, if so, determining that a malignant arrhythmia appears likely; and wherein the method also comprises the implantable device selecting N as follows; if nonsustained high rate event conditions have not been previously detected, a first number is selected; and if nonsustained high-rate event conditions have been previously identified, a second number larger than the first number is selected;
wherein the selection of the second number remains in place for use in identifying future malignant rhythms. - View Dependent Claims (24)
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Specification