Cardio-synchronous impedance measurement system for an implantable stimulation device
First Claim
1. An implantable electrical system for delivering therapeutic shocks to a heart of a patient, the system comprising:
- a lead, which extends into a ventricle of the heart, adapted for delivering electrical pulses;
control means for selectively inducing the lead to deliver an impedance measurement excitation pulse and pacing pulses to the ventricle to regulate the function of the heart;
measuring means, in response to the delivered excitation pulse, for measuring at least two instantaneous impedance measurements in the heart, wherein the impedance measurement excitation pulses are delivered to the heart at at least two different times during a measurement window to determine a single slope, the window being selected to coincide with contraction of the ventricle;
means for determining an impedance slope based on the instantaneous impedance measurements, the impedance slope being indicative of contractility of the heart; and
means for regulating the heart function based on the impedance slope.
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Accused Products
Abstract
In a pacing system, the pacing controller induces the leads to deliver an impedance measurement pulse to the right ventricle of the heart at at least a 15 ms interval during a window of time following detection of the R-wave or the delivery of a pacing pulse. The window of time corresponds to a period of ventricular ejection. The two or three measured impedance values are then used to determine an impedance slope that has a strong biological correlation to the contractility of the heart. The impedance slope is then used by the controller of the pacing system to adjust the delivery of pacing pulses for purposes such as maximizing contractility for a given AV delay, PV delay and pacing rate of pacing pulses.
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Citations
34 Claims
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1. An implantable electrical system for delivering therapeutic shocks to a heart of a patient, the system comprising:
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a lead, which extends into a ventricle of the heart, adapted for delivering electrical pulses; control means for selectively inducing the lead to deliver an impedance measurement excitation pulse and pacing pulses to the ventricle to regulate the function of the heart; measuring means, in response to the delivered excitation pulse, for measuring at least two instantaneous impedance measurements in the heart, wherein the impedance measurement excitation pulses are delivered to the heart at at least two different times during a measurement window to determine a single slope, the window being selected to coincide with contraction of the ventricle; means for determining an impedance slope based on the instantaneous impedance measurements, the impedance slope being indicative of contractility of the heart; and means for regulating the heart function based on the impedance slope. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A pacing system for delivering pacing pulses to a heart comprising:
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one or more leads positioned within one or more chambers of the heart including the right ventricle; and control means for selectively inducing the one or more leads to provide electrical pulses to the respective chamber of the heart, and for measuring an instantaneous impedance within the heart, wherein the control means induces the leads to provide a first type of electrical pulse for pacing purposes, and wherein the control means induces the leads to provide a second type of electrical pulse defined by a window which occurs during a contraction of the ventricle of the heart so that the instantaneous impedance within the heart can be measured by the control means at at least two instances within the window, wherein the control means uses the two measured instantaneous impedance values to determine an impedance slope that corresponds to the contractility of the ventricle of the heart, and wherein the control means includes means for altering the delivery of the first electrical pulse to the heart based on the impedance slope. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An implantable system for providing therapeutic electrical pulses to the heart of a patient comprising:
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delivery means for delivering electrical pulses to a ventricle of the heart; control means for controlling the delivery of the electrical pulses to the ventricle of the heart, wherein the control means induces the delivery means to provide a first type of electrical pulse for therapeutic purposes and a second type of electrical pulse for impedance measurement purposes; and means for adjusting the first electrical pulses to optimize hemodynamics by measuring at least two instantaneous impedance measurements during a window defined by contraction of the ventricle of the heart to determine a single impedance slope representative of the instantaneous impedance slope that corresponds to the contractility of the ventricle of the heart. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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28. A method of providing electrical pulses to the heart of a patient comprising the steps of:
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sensing the occurrence of either an evoke contraction or a naturally occurring contraction; providing two impedance measurement pulses to a ventricle of the heart during either the evoked contraction or the naturally occurring contraction; obtaining two instantaneous impedance measurements in response to the two impedance measurement pulses; determining an impedance slope based on the two instantaneous impedance measurements; and adjusting the delivery of one or more pacing electrical pulses to the heart based upon the determined impedance slope. - View Dependent Claims (29, 30, 31, 32, 33)
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34. An implantable electrical system for delivering therapeutic stimulation to a patient'"'"'s heart, the system comprising:
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a lead, which extends into a ventricle of the heart, adapted for delivering electrical pulses; a pulse generator, coupled to the lead, that selectively generates one of tissue stimulation pulses or impedance excitation pulses to the ventricle, wherein the impedance excitation pulses are delivered at two different times during a period of ventricular ejection corresponding to contraction of the ventricle; an impedance measuring circuit, coupled to the lead, that measures an instantaneous impedance at the two different times the excitation pulses are delivered during the ventricular contraction; a processor system, coupled to the impedance sensing circuit and the pulse generator, that determines an impedance slope based on the two instantaneous impedance measurements, the impedance slope being indicative of contractility of the ventricle, and that regulates the generation of the tissue stimulation pulses based on the impedance slope.
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Specification