Determination of an average hemodynamic index for an active implantable medical device such as cardiac pacemaker, defibrillator, cardiovertor and/or multisite device
First Claim
1. An active implantable medical device, in particular a cardiac pacemaker, defibrillator, cardiovertor and/or multisite device, having at least one electrode terminal placed in each of at least two distinct respective sites including at least one ventricular site and one atrial site, comprising:
- means for measuring an intracardiac impedance signal correlated to the instantaneous blood flow, said means comprising a pulse generator providing a current injection and circuit for collecting a differential potential across said respective electrode terminals in response to said current injection; and
means for determining periodically, in response to said measured impedance signal, an average hemodynamic index evaluated over a number of successive cardiac cycles satisfying a plurality of preset of measurement conditions, said means including;
control means for checking a state of the patient and criteria corresponding to a set of predetermined measurement conditions and for inhibiting the determination of said average hemodynamic index if said criteria set are not satisfied;
measuring means for determining a plurality of the measured impedance signal samples over a first duration corresponding to a systole of one cardiac cycle;
integrating means for determining, in response to said determined samples, a value representative of the blood volume ejected throughout said systole; and
calculating means for establishing said average hemodynamic index in response to a plurality of said values successively determined by the integrating means over a plurality of cardiac cycles.
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Accused Products
Abstract
An active implantable medical device such as a cardiac pacemaker, defibrillator, cardiovertor and/or multisite device that is able to determine and average a hemodynamic index parameter. The intracardiac impedance signal is correlated to the instantaneous blood flow, and is used to determine periodically an average hemodynamic index (Dave) evaluated over several cardiac cycles under certain preset measurement conditions. For example, the preset conditions include checking that the state of the patient and of the device satisfies, the criteria (stages 12-20) defining predetermined measurement conditions, and inhibiting the determination of the aforesaid hemodynamic index if these criteria are not satisfied. A plurality of samples (Zij) of the measured impedance signal are collected over a length of time (Ti) of the systole of one cardiac cycle. Using the aforesaid samples, a value (Di) representative of the blood volume ejected throughout this systole is determined by integrating the samples over the time period. Then, average hemodynamic index (Dave) is calculated from a plurality of such integrated sample values successively determined over a plurality (N2) of cardiac cycles.
27 Citations
10 Claims
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1. An active implantable medical device, in particular a cardiac pacemaker, defibrillator, cardiovertor and/or multisite device, having at least one electrode terminal placed in each of at least two distinct respective sites including at least one ventricular site and one atrial site, comprising:
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means for measuring an intracardiac impedance signal correlated to the instantaneous blood flow, said means comprising a pulse generator providing a current injection and circuit for collecting a differential potential across said respective electrode terminals in response to said current injection; and
means for determining periodically, in response to said measured impedance signal, an average hemodynamic index evaluated over a number of successive cardiac cycles satisfying a plurality of preset of measurement conditions, said means including;
control means for checking a state of the patient and criteria corresponding to a set of predetermined measurement conditions and for inhibiting the determination of said average hemodynamic index if said criteria set are not satisfied;
measuring means for determining a plurality of the measured impedance signal samples over a first duration corresponding to a systole of one cardiac cycle;
integrating means for determining, in response to said determined samples, a value representative of the blood volume ejected throughout said systole; and
calculating means for establishing said average hemodynamic index in response to a plurality of said values successively determined by the integrating means over a plurality of cardiac cycles. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification