Abstract: A rate-responsive active implantable medical device, in particular a cardiac pacemaker, defibrillator or cardiovertor, which is protected from the effects of bradycardia- and/or tachycardia-dependent extrasystoles. The device is able to stimulate at least one cardiac cavity by delivering low-energy pulses to the heart at a frequency determined by the device, and evaluates the activity level of the patient bearing the device and discriminates between phases of rest, normal activity and effort. Further, the device is capable of adjusting the frequency according to the determined activity level, more particularly decreasing the base frequency to a given minimum level during a rest phase. The device also detects the occurrence of brady-dependent extrasystoles, determines a corresponding extrasystole rate, and then increases the base frequency minimum level when the extrasystole rate exceeds a predetermined threshold during the rest phase.

Abstract: An active implantable medical device having an automatic DDD/AAI mode switching. This device includes sensing spontaneous atrial and ventricular events, detecting an atrio-ventricular block and stimulating the ventricle and atrium, the ventricular stimulation being applied on the detection of an atrio-ventricular block (AVB ), after completion of a programmed atrio-ventricular delay begun on an atrial event. The device also includes a control algorithm that discriminates a paroxystic AVB from a chronic AVB. In the event of an established chronic AVB, the device stops the automatic mode switching, switches to the DDD mode, and reprograms the atrio-ventricular delay with a shorter value than that which previously existed. The AVB discrimination can be based on, in a first phase, a suspicion of a chronic AVB, and in a second phase, a confirmed presence of a chronic AVB in the event that consecutive suspicions of chronic AVB persist for a predetermined length of time.

Abstract: An active implantable medical device, such as a pacemaker, defibrillator, cardiovertor and/or a multisite device, having an improved detection of late atrial extrasystoles. The device detects atrial events (EvtA); applies a first window forming a relative atrial refractory period (DARRP) for discriminating (filtering) atrial extrasystoles of an early or average prematurity, and reacts to a variation of the sinusal atrial rate by certain control algorithms. It also applies the detected atrial events to a second window (DLE), distinct from the first window and of longer duration, for the discrimination of the atrial extrasystoles having a low prematurity, called late extrasystoles. The duration of the second window is a variable duration, defined as a fraction of the current average atrial interval (AAI). Further, the second window is used to inhibit temporarily any reaction to a variation of the sinusal atrial rate, in the event of detection of an atrial event inside the second window.

Abstract: An active implantable medical device with a sophisticated management of the refractory periods. Such devices typically include a detection circuit and a stimulation circuit and a circuit which applies a refractory period to the detection circuit, including an absolute refractory period (ARP), which can be fixed or pre-programmed, and a relative refractory period (RRP), which is variable. The relative refractory period includes a succession of elementary periods (X) of a fixed or programmable duration, which elementary period is further subdivided into sub-periods (Y) such that an elementary period X is retriggered or restarted at the end of a sub-period Y if a residual potential of a level higher than a given threshold is detected at output of the detection circuit during that sub-period. In the absence of a detected residual potential being detected during the successive sub-periods comprising the elementary period, then the refractory period ends.

Abstract: An active implantable medical device, notably a cardiac pacemaker, enslaved to at least a physiological parameter which comprises at least one effort sensor (MV) having a plurality of determinable states, for measuring a primarily physiological parameter and delivering a signal which is a function of effort exerted by a patient bearing the device and at least one activity sensor (G) having a plurality of determinable states, for measuring a primarily physical parameter and delivering a signal which is indicative of the activity of the patient bearing the device. The determinable states of the respective sensors are determined and the relative sequence of successive changes in the state of the respective sensors are identified and analyzed periodically according to predetermined criteria. A command escape interval (IECONSIG) controlling the enslaved functioning of the device is determined from the analyzed states of the sensors.

Abstract: An active implantable medical device, in particular a pacemaker, defibrillator and/or cardiovertor, able to identify and eliminate the artifacts of the detection of cardiac events. This device detects spontaneous events in a ventricular and/or atrial cavity cardiac; measures the intervals separating the successive detected events collected by the detection circuits; analyzes the cardiac rate of heartbeat, according to the measured values of intervals; and eliminates double detections of the same cardiac event, namely when an event detected is followed of an artifact likely to be also detected. The elimination of double detections is performed by seeking to identify an alternation of short intervals (t1, t3, t5, . . . ) and long intervals (t2, t4, t6, . . . ) in the successive measured intervals (t1, t2, t3, t4, t5, t6, . . . ) separating a series of consecutive events (R1, R′1, R2, R′2, R3, R′3, . . .

Abstract: A rate responsive active implantable medical device having at least one effort sensor, measuring a parameter which is predominantly physiological (VE) and delivering an output signal which is a function of the effort developed by a patient carrying the device, and at least one activity sensor, measuring a parameter which predominantly physical. The devices operates to (a) measure periodically at the two sensors “couples of values” (12, 14, 16; 22, 24, 26) corresponding to a given level of effort developed by the patient; (b) establish a characteristic function of the measured couples of values (10, 20), and (c) evaluate over the course of time this established characteristic, by seeking a possible increase in the signals delivered by the effort sensor as compared to the signals delivered by the activity sensor, indicative of the patient's metabolic demand (cardiac output requirements).

Abstract: An active implantable medical device, particularly a cardiac pacemaker, defibrillator and/or cardiovertor capable of detecting the spontaneous depolarisation of the myocardium and determining the instant of its occurrence, which device detects the spontaneous depolarisation (10) of the myocardium through processing of a cardiac signal (E), delivers an information (t) of occurrence of a depolarisation and conditionally discriminates, preferably during consecutive limited time intervals ([t-50, t+200]), a unique characteristic of the cardiac signal giving a temporal information (T.sub.1, T.sub.2, T.sub.3) on the instant of occurrence of the depolarisation. The unique characteristic can particularly be a predetermined singularity of the cardiac signal such as an extreme, particularly the extreme negative, of the first derivative (dE/dt) of the cardiac signal.

Abstract: An active implantable medical device, especially of the cardiac pacemaker, defibrillator and/or cardiovertor type, and method for the reduction of episodes of arrhythmia, and especially of atrial arrhythmias. The device operates by detecting events of spontaneous electrical activity in a cardiac cavity, especially the atrium; delivering a stimulation to the aforementioned cardiac cavity, which stimulation is controlled according to an actual escape interval such that, at each cardiac cycle, a stimulation is delivered to the cavity if no spontaneous event is detected by the end of a time corresponding to the end of the period of escape interval since the last spontaneous event or the last stimulation in the cavity; counting of the number of successive stimulated events; and discriminating between events detected in the cavity of an extrasystole origin or a non-extrasystole origin.

Abstract: An apparatus and process for the determination of criterion of a frequent presence or of the gravity of atrial and/or ventricular extra-systoles in an active implantable medical apparatus. The signals corresponding to cardiac events in at least one cardiac cavity are detected and the occurrence of extra-systoles are detected. At the detection of every extra-systole, a ponderation (i.e., weight or magnitude of increment) is attributed to the extra-systole, and a count of extra-systoles with the attributed ponderation applied for the detected extra-systole is made. The count also is decremented at each detected cardiac cycle not having a detected extra-systole, such that the decrement also may have an associated ponderation. The count thus provides a criterion of extra-systole frequency and gravity (seriousness).

Abstract: An active implantable medical device, especially of a cardiac pacemaker, defibrillator and/or cardiovertor type, having a dual chamber stimulation function and protection against cross-sensing atrio-ventricular phenomena. Cardiac events, spontaneous or stimulated, are detected in a first cavity, preferably the atrium, and a second cavity is stimulated, preferably the ventricle, The detection and confirmation of cross-sensing is performed by detecting in the atrium a signal coming from a depolarization consecutive to a preceding stimulation of the ventricle, and distinguishing such a signal from a signal resulting from spontaneous activity of the atrium.

Abstract: A device and process for the processing of troubles of the atrial rhythm for an active implantable medical device. The device detects signals from at least the atrial cardiac activity, and stimulates both the atrial and ventricular cardiac cavities, detects the occurrence of atrial extra-systoles (ESA), and determines and releases an intermediate atrial escape interval (PPinter). The intermediate atrial escape interval is then applied during the detection of an atrial extra-systole for improved processing.

Abstract: An active implantable medical device of the defibrillator/cardiovertor type with advanced tachycardia discrimination in which the device monitors the atrial and ventricular activity, suspects and confirms the presence of tachycardia episodes in the monitored activity, and operates a classification algorithm to discriminate between ventricular tachycardias and supra-ventricular tachycardias according to predetermined criteria and a given adjustment of these criteria, and to authorize the releasing of a shock therapy defibrillation, and/or cardioversion and/or anti-tachycardia ventricular stimulation in the presence ventricular tachycardias and to inhibit delivery of a shock therapy in the presence of a supra-ventricular tachycardias, or instead to release an atrial therapy.

Abstract: An active implantable medical device of the defibrillator/cardiovertor type with an improved tachycardia discrimination for utilizing the delivery of a therapy of defibrillation and/or cardioversion and/or antitachycardia stimulation in the ventricle and/or atrium. The atrial and ventricular activity is monitored, and suspected tachycardia episodes in the monitored activity is tested and confirmed, the stability of RR intervals and the stability of associated PR interval are analyzed. The classification discriminates tachycardias detected as between ventricular tachycardias and supra-ventricular tachycardias, and authorizes delivery of a shock therapy in the presence of a confirmed ventricular tachycardias, or inhibits delivery of a shock therapy in response to a confirmed supra-ventricular tachycardia. Where appropriate, the classification also releases an atrial therapy.

Abstract: An active implantable medical device, particularly a rate responsive cardiac pacemaker having reduced power consumption. The device has a first sensor to measure a parameter that is used to control at least one function of the device, particularly a cardiac stimulation frequency, and a first sensing circuit for receiving and processing the output signals delivered by the first sensor. A switch is used to switch in and out of service the first sensing circuit according to the determined activity level of the patient bearing the device. The first sensing circuit determines a state of activity of the first sensor, this state being susceptible to take, according to predetermined criteria, a calculated value that is representative of a state of rest of the patient. The first sensing circuit is then switched according to the determined state of activity of the first sensor being established at the state of rest.

Abstract: An active implantable medical device, particularly a cardiac pacemaker, enslaved to at least one physiological parameter. The device is susceptible to function in an enslaved mode by controlling at least one function, particularly that of a cardiac stimulation frequency, based on at least one physiological parameter, and includes at least one effort sensor, measuring a predominantly physiological parameter and delivering an output signal that is a function of the effort developed by a patient bearing the device and at least one activity sensor, especially a sensor having a response time that is more rapid than the effort sensor, for measuring a predominantly physical parameter.

Abstract: A process for controlling a dual chamber cardiac pacemaker having a fallback mode of de-synchronization of the ventricular stimulation when the atrial rhythm exceeds an allowable level, and a mode of progressive re-synchronization in case of the return of the atrial rhythm to the allowable level. In the process:(a) at each detection of an atrial depolarization, one defines a window of Detection of the Acceleration of the Atrial Rhythm (DAAR) whose duration is a function the preceding atrial rhythm, evaluated according to the duration of one or an average of several of preceding atrial intervals,(b) at the detection of the next atrial depolarization, one starts an Atrial Escape Interval (AEI), and(c) if this next atrial depolarization has occurred in the DAAR window, one commands if necessary a consecutiveatrial stimulation according to the AEI thus defined.

Abstract: An active implantable medical device, notably a cardiac pacemaker or fibrillator, which detects the instantaneous cardiac rhythm, spontaneous or stimulated, of the bearer of the device, and delivers stimulation pulses with a variable escape interval and which increases gradually this escape interval. The gradual increase of the escape interval is obtained by memorizing information corresponding to the evolution of the cardiac rhythm sensed by a conventional detection circuit over a first time period, wherein the escape interval to be adjusted is later in time to the memorized information, notably by determining a variable rate of increase of the escape interval, which variable rate is essentially determined as a function of the memorized information, and/or by operating an integration of the previously detected cardiac rhythm.

Abstract: Process of control of the base frequency of a cardiac pacemaker having at least one sensor monitoring a physiological parameter. Rest phases and resumption of activity phases are detected to adapt automatically the base frequency of the pacemaker to the relative periods of rest and activity of the patient. Thus, the base frequency is allowed to decrease below the normally programmed base frequency in response to actual patient rest, to encourage a low spontaneous cardiac rhythm to inhibit pacing.

Abstract: The process of determining a criterion of activity of a sensor used to measure a parameter of enslavement in an active implantable medical device. The process is characterized by the following steps:a) acquisition of successive samples of the representative value of the parameter from a signal collected by the sensor,b) calculation over a first interval of time of a first average value (AVE.sub.-- SENSOR.sub.-- SHORT.sub.-- TERM) of the activity from the samples acquired by the sensor;c) calculation over a second interval of time, greater than the first, of a second average value (AVE.sub.-- SENSOR.sub.-- 24H) of the activity of the sensor from acquired samples, andd) determination of a criterion of activity of the sensor, by comparison of the first average value and the second average value, notably by giving to the criterion of activity a first value (Rest) defining a state of rest of the patient if the first average value (AVE.sub.-- SENSOR.sub.-- SHORT.sub.