CLOSED LOOP IMPEDANCE-BASED CARDIAC RESYNCHRONIZATION THERAPY SYSTEMS, DEVICES, AND METHODS
First Claim
1. A system comprising:
- an implantable medical device comprising;
a physiological conductivity characteristic measurement circuit, including terminals configured to be coupled to electrodes for association with different first and second regions of a same first ventricle of a heart, respectively, and configured to be coupled to a reference electrode location separate from each of the first and second regions, to provide first and second conductivity characteristics respectively associated with the first and second regions; and
a processor circuit, coupled to the conductivity characteristic measurement circuit to receive signals indicative of the first and second conductivity characteristics during the cardiac cycle, the processor configured to perform instructions to measure a phase difference between the first and second conductivity characteristics to provide an indication of a degree of synchrony or asynchrony between the first and second regions, the processor further configured to perform instructions to automatically adjust in a closed-loop manner, using the measured phase difference as an error signal, a cardiac resynchronization therapy parameter that synchronizes contraction of the first and second regions in a way that tends to reduce the phase difference during a subsequent cardiac cycle.
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Abstract
This document discusses, among other things, systems, devices, and methods measure an impedance and, in response, adjust an atrioventricular (AV) delay or other cardiac resynchronization therapy (CRT) parameter that synchronizes left and right ventricular contractions. A first example uses parameterizes a first ventricular volume against a second ventricular volume during a cardiac cycle, using a loop area to create a synchronization fraction (SF). The CRT parameter is adjusted in closed-loop fashion to increase the SF. A second example measures a septal-freewall phase difference (PD), and adjusts a CRT parameter to decrease the PD. A third example measures a peak-to-peak volume or maximum rate of change in ventricular volume, and adjusts a CRT parameter to increase the peak-to-peak volume or maximum rate of change in the ventricular volume.
4 Citations
20 Claims
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1. A system comprising:
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an implantable medical device comprising; a physiological conductivity characteristic measurement circuit, including terminals configured to be coupled to electrodes for association with different first and second regions of a same first ventricle of a heart, respectively, and configured to be coupled to a reference electrode location separate from each of the first and second regions, to provide first and second conductivity characteristics respectively associated with the first and second regions; and a processor circuit, coupled to the conductivity characteristic measurement circuit to receive signals indicative of the first and second conductivity characteristics during the cardiac cycle, the processor configured to perform instructions to measure a phase difference between the first and second conductivity characteristics to provide an indication of a degree of synchrony or asynchrony between the first and second regions, the processor further configured to perform instructions to automatically adjust in a closed-loop manner, using the measured phase difference as an error signal, a cardiac resynchronization therapy parameter that synchronizes contraction of the first and second regions in a way that tends to reduce the phase difference during a subsequent cardiac cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system comprising:
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an implantable medical device comprising; a physiological impedance measurement circuit, including terminals configured to be coupled to electrodes for association with different septal and freewall regions of a same first ventricle of a heart, respectively, and configured to be coupled to a reference electrode location separate from each of the septal and freewall regions, to provide first and second impedances respectively associated with the septal and freewall regions; and a processor circuit, coupled to the impedance measurement circuit to receive signals indicative of the first and second impedances during the cardiac cycle, the processor configured to perform instructions to measure a phase difference between the first and second impedances to provide an indication of a degree of synchrony or asynchrony between the septal and freewall regions, the processor further configured to perform instructions to automatically adjust in a closed-loop manner, using the measured phase difference as an error signal, a cardiac resynchronization therapy parameter that synchronizes contraction of the septal and freewall regions in a way that tends to reduce the phase difference during a subsequent cardiac cycle. - View Dependent Claims (13, 14, 15, 16)
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17. A system comprising:
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an implantable medical device comprising; a physiological impedance measurement circuit, including terminals configured to be coupled to electrodes for association with different septal and freewall regions of a same first ventricle of a heart, respectively, and configured to be coupled to a reference electrode location separate from each of the septal and freewall regions, to provide first and second impedances respectively associated with the septal and freewall regions; and a processor circuit, coupled to the impedance measurement circuit to receive signals indicative of the first and second impedances during the cardiac cycle, the processor configured to perform instructions to measure a phase difference between the first and second impedances to provide an indication of a degree of synchrony or asynchrony between the septal and freewall regions, the processor further configured to perform instructions to automatically adjust in a closed-loop manner, using the measured phase difference as an error signal, a cardiac resynchronization therapy parameter that synchronizes contraction of the septal and freewall regions in a way that tends to reduce the phase difference during a subsequent cardiac cycle, in which the automatically adjusting the cardiac resynchronization therapy parameter includes adjusting an intraventricular delay. - View Dependent Claims (18, 19, 20)
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Specification