System and method for evaluating mechanical cardiac dyssynchrony based on multiple impedance vectors using an implantable medical device
First Claim
1. A method for use with an implantable medical device for implant within a patient, the method comprising:
- detecting a plurality of cardiogenic impedance signals along different sensing vectors within the patient;
detecting a measure of mechanical dyssynchrony in the heart of the patient based on a comparison of the cardiogenic impedance signals, including detecting abnormally contracting segments, if any, within the heart of the patient; and
controlling at least one device function based on the measure of mechanical dyssynchrony;
wherein detecting the measure of mechanical dyssynchrony includesdelivering a pacing pulse to the heart of the patient;
for each of the cardiogenic impedance signals, examining the signal to detect a maximum in a first time derivative of the signal after pulse delivery and then measuring the time delay from the pulse to the maximum in the first time derivative; and
comparing the peak velocity delay times derived from the cardiogenic impedance signals to generate the measure of mechanical dyssynchrony.
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Abstract
Techniques are provided for evaluating mechanical dyssynchrony within the heart of patient in which a pacemaker, implantable cardioverter-defibrillator (ICD) or other medical device is implanted. In one example, a set of cardiogenic impedance signals are detected along different sensing vectors passing through the heart of the patient, particularly vectors passing through the ventricular myocardium. A measure of mechanical dyssynchrony is detected based on differences, if any, among the cardiogenic impedance signals detected along the different vectors. In particular, differences in peak magnitude delay times, peak velocity delay times, peak magnitudes, and waveform integrals of the cardiogenic impedance signals are quantified and compared to detect abnormally contracting segments, if any, within the heart of the patient. Warnings are generated upon detection of any significant increase in mechanical dyssynchrony. Diagnostic information is recorded for clinical review. Pacing therapies such as cardiac resynchronization therapy (CRT) can be activated or controlled in response to mechanical dyssynchrony to improve the hemodynamic output of the heart.
33 Citations
27 Claims
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1. A method for use with an implantable medical device for implant within a patient, the method comprising:
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detecting a plurality of cardiogenic impedance signals along different sensing vectors within the patient; detecting a measure of mechanical dyssynchrony in the heart of the patient based on a comparison of the cardiogenic impedance signals, including detecting abnormally contracting segments, if any, within the heart of the patient; and controlling at least one device function based on the measure of mechanical dyssynchrony; wherein detecting the measure of mechanical dyssynchrony includes delivering a pacing pulse to the heart of the patient; for each of the cardiogenic impedance signals, examining the signal to detect a maximum in a first time derivative of the signal after pulse delivery and then measuring the time delay from the pulse to the maximum in the first time derivative; and comparing the peak velocity delay times derived from the cardiogenic impedance signals to generate the measure of mechanical dyssynchrony. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for use with an implantable medical device for implant within a patient, the method comprising:
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detecting a plurality of cardiogenic impedance signals along different sensing vectors within the patient; detecting a measure of mechanical dyssynchrony in the heart of the patient based on a comparison of the cardiogenic impedance signals, including detecting abnormally contracting segments, if any, within the heart of the patient; and controlling at least one device function based on the measure of mechanical dyssynchrony; wherein detecting the measure of mechanical dyssynchrony includes detecting differences in peak velocity delay times observed within the cardiogenic impedance signals and identifying late contracting segments within the heart of the patient by identifying particular cardiogenic impedance signals wherein the peak velocity delay time is significantly longer than the peak velocity delay times of the other cardiogenic impedance signals.
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9. A method for use with an implantable medical device for implant within a patient, the method comprising:
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detecting a plurality of cardiogenic impedance signals along different sensing vectors within the patient; detecting a measure of mechanical dyssynchrony in the heart of the patient based on a comparison of the cardiogenic impedance signals, including detecting abnormally contracting segments, if any, within the heart of the patient; and controlling at least one device function based on the measure of mechanical dyssynchrony; wherein detecting the measure of mechanical dyssynchrony includes detecting differences in integrals derived from the cardiogenic impedance signals. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A system for use with an implantable medical device for implant within a patient, the system comprising:
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a multiple cardiogenic impedance signal detector operative to detect a plurality of cardiogenic impedance signals along different sensing vectors within the patient; and a mechanical dyssynchrony evaluation system operative to detect a measure of mechanical dyssynchrony in the heart of the patient based on a comparison of the cardiogenic impedance signals, including detecting abnormally contracting segments, if any, within the heart of the patient; wherein to detect the measure of mechanical dyssynchrony the mechanical dyssynchrony evaluation system is operative to deliver a pacing pulse to the heart of the patient;
for each of the cardiogenic impedance signals, examine the signal to detect a maximum in a first time derivative of the signal after pulse delivery and then measure the time delay from the pulse to the maximum in the first time derivative; and
compare the peak velocity delay times derived from the cardiogenic impedance signals to generate the measure of mechanical dyssynchrony. - View Dependent Claims (20, 21, 22)
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23. A method for use with an implantable medical device for implant within a patient, the method comprising:
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detecting a plurality of cardiogenic impedance signals along different sensing vectors within the patient; detecting a measure of mechanical dyssynchrony in the heart of the patient based on a comparison of the cardiogenic impedance signals, including detecting differences in integrals of the cardiogenic impedance signals; and controlling at least one device function based on the measure of mechanical dyssynchrony.
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24. A system for use with an implantable medical device for implant within a patient, the system comprising:
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a multiple cardiogenic impedance signal detector operative to detect a plurality of cardiogenic impedance signals along different sensing vectors within the patient; and a mechanical dyssynchrony evaluation system operative to detect a measure of mechanical dyssynchrony in the heart of the patient based on a comparison of the cardiogenic impedance signals, including detecting abnormally contracting segments, if any, within the heart of the patient; wherein to detect the measure of mechanical dyssynchrony the mechanical dyssynchrony evaluation system is operative to detect differences in integrals derived from the cardiogenic impedance signals. - View Dependent Claims (25, 26, 27)
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Specification