Adjusting the maximum ventricular stimulation frequency according to the hemodynamic state of the patient in an active implantable medical device
First Claim
1. An active implantable medical device, comprisingmeans for delivering stimulation pulses to at least one site of a cardiac cavity;
- means for controlling a delivery frequency of the stimulation pulses;
means for limiting to a maximum frequency the delivery frequency of the stimulation pulses;
means for measuring an intracardiac bio-impedance;
means for adjusting the maximum frequency to a value that is a function of the measured intracardiac bio-impedance;
means for evaluating a parameter representative of cardiac flow based upon a signal delivered by the means for measuring the intracardiac bio-impedance;
means for changing the delivery frequency of the stimulation pulses in a successive cardiac cycle by a programmable variation (X %);
means for measuring a change in the parameter representative of cardiac flow over the successive cardiac cycle;
means for evaluating a first condition, the first condition being that the ratio of the change in the parameter representative of cardiac flow with respect to the change of the delivery frequency of the stimulation pulses over the successive cardiac cycle is greater than a threshold;
means for evaluating a second condition if the first condition is met, the second condition being that the change of the parameter representative of cardiac flow is greater than a programmable variation (y %), wherein the means for adjusting the maximum frequency adjusts the maximum frequency when the second condition is not met; and
means for operating the means for adjusting the maximum frequency if the second condition is met in an iterative operation to control successive programmable variations of the delivery frequency of the stimulation pulses in response to the change in the parameter representative of cardiac flow with each iteration.
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Accused Products
Abstract
Adjusting the maximum ventricular stimulation frequency according to the hemodynamic state of the patient in an active implantable medical device. This device provides for limiting ventricular stimulation to a maximum frequency (Fmax), the rate of delivery of the stimulation pulses, measuring an intracardiac bio-impedance (Zn, Zn+1), and adjusting the maximum frequency according to the measured intracardiac bio-impedance. The adjusting process can include evaluating a parameter representative of the cardiac flow (dn, dn+1) utilizing the intracardiac signal of bio-impedance; controlling a predetermined variation (X %) of the frequency (f) of delivery of the stimulation pulses; evaluating the correlative variation (y %) of the cardiac flow; and adjusting the value of the maximum frequency (Fmax) according to the variation of the cardiac flow thus evaluated.
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Citations
11 Claims
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1. An active implantable medical device, comprising
means for delivering stimulation pulses to at least one site of a cardiac cavity; -
means for controlling a delivery frequency of the stimulation pulses; means for limiting to a maximum frequency the delivery frequency of the stimulation pulses; means for measuring an intracardiac bio-impedance; means for adjusting the maximum frequency to a value that is a function of the measured intracardiac bio-impedance; means for evaluating a parameter representative of cardiac flow based upon a signal delivered by the means for measuring the intracardiac bio-impedance; means for changing the delivery frequency of the stimulation pulses in a successive cardiac cycle by a programmable variation (X %); means for measuring a change in the parameter representative of cardiac flow over the successive cardiac cycle; means for evaluating a first condition, the first condition being that the ratio of the change in the parameter representative of cardiac flow with respect to the change of the delivery frequency of the stimulation pulses over the successive cardiac cycle is greater than a threshold; means for evaluating a second condition if the first condition is met, the second condition being that the change of the parameter representative of cardiac flow is greater than a programmable variation (y %), wherein the means for adjusting the maximum frequency adjusts the maximum frequency when the second condition is not met; and means for operating the means for adjusting the maximum frequency if the second condition is met in an iterative operation to control successive programmable variations of the delivery frequency of the stimulation pulses in response to the change in the parameter representative of cardiac flow with each iteration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An active implantable medical device, having computer readable instructions stored in memory for performing the steps of:
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delivering stimulation pulses to at least one site of a cardiac cavity; controlling a delivery frequency of the stimulation pulses; limiting to a maximum frequency the delivery frequency of the stimulation pulses; measuring an intracardiac bio-impedance; adjusting the maximum frequency to a value that is a function of the measured intracardiac bio-impedance; evaluating a parameter representative of cardiac flow based upon a signal delivered by the means for measuring the intracardiac bio-impedance; changing the delivery frequency of the stimulation pulses in a successive cardiac cycles, causing a change of the delivery frequency of the stimulation pulses by a programmable variation (X %); measuring a change in the parameter representative of cardiac flow over the successive cardiac cycle; evaluating a first condition, the first condition being that the ratio of the change in the parameter representative of cardiac flow with respect to the change of the delivery frequency of the stimulation pulses over the successive cardiac cycle is greater than a threshold; evaluating a second condition if the first condition is met, the second condition being that the change of the parameter representative of cardiac flow is greater than a programmable variation (y %), wherein the maximum frequency is adjusted when the second condition is not met; and adjusting the maximum frequency if the second condition is met in an iterative operation to control successive programmable variations of the delivery frequency of the stimulation pulses in response to the change in the parameter representative of cardiac flow with each iteration.
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Specification