Closed loop impedance-based cardiac resynchronization therapy systems, devices, and methods
First Claim
1. A machine-assisted method comprising:
- measuring a first impedance signal, the first impedance signal indicative of a volume of a first ventricle of a heart as the first ventricle expands and contracts during a cardiac cycle;
using the first impedance signal to measure a maximum rate of change of volume of the first ventricle occurring exclusively in a systole portion of a cardiac cycle; and
automatically adjusting, using the maximum rate of change of volume, at least one cardiac resynchronization therapy parameter that synchronizes left and right ventricular heart contractions, the automatically adjusting tending to increase the maximum rate of change in the volume over at least one 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.
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Citations
25 Claims
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1. A machine-assisted method comprising:
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measuring a first impedance signal, the first impedance signal indicative of a volume of a first ventricle of a heart as the first ventricle expands and contracts during a cardiac cycle; using the first impedance signal to measure a maximum rate of change of volume of the first ventricle occurring exclusively in a systole portion of a cardiac cycle; and automatically adjusting, using the maximum rate of change of volume, at least one cardiac resynchronization therapy parameter that synchronizes left and right ventricular heart contractions, the automatically adjusting tending to increase the maximum rate of change in the volume over at least one subsequent cardiac cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A system comprising:
an implantable cardiac function management device comprising; an impedance measurement circuit, including terminals configured to be coupled to electrodes for association with a first ventricle of a heart to measure an impedance signal to determine a volume of the first ventricle during a cardiac cycle of the heart; and a processor circuit, coupled to the impedance measurement circuit to receive information about the impedance signal, the processor configured to execute or interpret instructions to measure a maximum rate of change in volume of the first ventricle occurring exclusively in a systole portion of the cardiac cycle, the processor further configured to execute or interpret instructions to automatically adjust in a closed-loop manner, using the measured maximum rate of change in the volume, a cardiac resynchronization therapy parameter that synchronizes left and right ventricular heart contractions in a manner that tends to increase the maximum rate of change in the volume during a subsequent cardiac cycle. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
Specification