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US 8,712,521 B2Granted
Method and apparatus for controlling cardiac resynchronization therapy using cardiac impedance
AssigneeCardiac Pacemakers, Inc.
InventorYunlong Zhang
Life of this patent
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Abstract
This document discusses, among other things, systems, devices, and methods for measuring cardiac impedances and producing one or more resynchronization index parameters each indicative of a cardiac synchrony or asynchrony using the measured cardiac impedances. In one example, the one or more resynchronization index parameters are used to adjust one or more pacing parameters of a cardiac resynchronization therapy.
Claims20
A system for monitoring a heart having first and second ventricles, the system comprising:
- a device including:
- an impedance measurement circuit, including terminals configured to be coupled to electrodes in association with the first ventricle to measure a first impedance signal that is substantially indicative of a volume of the first ventricle as the first ventricle expands and contracts during a cardiac cycle of the heart and in association with the second ventricle to measure a second impedance signal that is substantially indicative of a volume of the second ventricle as the second ventricle expands and contracts during the cardiac cycle;
- and
- a processor, coupled to the impedance measurement circuit to receive information about the first and second impedance signals over the cardiac cycle, the processor configured to perform instructions to detect a first peak of the first impedance signal during the cardiac cycle, detect a second peak of the second impedance signal during the cardiac cycle, determine a first type point on the first impedance signal, the first type point being a function of the first peak, determine a second type point on the second impedance signal, the second type point being a function of the second peak, compute a first slope of the first impedance signal at the first type point on the first impedance signal, compute a second slope of the second impedance signal at the second type point on the second impedance signal, and produce a first resynchronization parameter using a difference between the first slope and the second slope, the first resynchronization parameter indicative of a degree of cardiac mechanical synchrony or asynchrony between the first and second ventricles.
1 more element
A system for monitoring a heart having first and second ventricles, the system comprising:
- a device comprising:
- an impedance measurement circuit, including terminals configured to be coupled to electrodes in association with the first ventricle to measure a first impedance signal that is substantially indicative of a volume of the first ventricle as the first ventricle expands and contracts during a cardiac cycle of the heart and in association with the second ventricle to measure a second impedance signal that is substantially indicative of a volume of the second ventricle as the second ventricle expands and contracts during the cardiac cycle;
- a depolarization detector to detect a first ventricular depolarization of the first ventricle and a second ventricular depolarization of the second ventricle during the cardiac cycle;
- and
- a processor, coupled to the impedance measurement circuit to receive information about the first and second impedance signals over the cardiac cycle, the processor configured to perform instructions to detect a first peak of the first impedance signal during the cardiac cycle, detect a second peak of the second impedance signal during the cardiac cycle, measure a first time interval between the first ventricular depolarization and the first peak, measure a second time interval between the second ventricular depolarization and the second peak, and produce a first resynchronization parameter using a difference between the first time interval and the second time interval, the first peak being a first point at which the first impedance signal reaches a first maximum value, the second peak being a second point at which the second impedance signal reaches a second maximum value, the first resynchronization parameter indicative of a degree of cardiac mechanical synchrony or asynchrony between the first and second ventricles.
2 more elements
Dependencies are inferred from the claim text.