Abstract: An active implantable medical device, in particular a pacemaker, defibrillator and/or cardiovertor of the multisite type, having an improved resynchronized cardiac stimulation capability for the treatment of cardiac insufficiency in which the maximum stimulation frequency Fmax is gradually increased over time, starting from an initial value of F0 up to a target value of F1. Moreover, when the device shortens the atrio-ventricular delay as the instantaneous heart rate increases, the device also compares the instantaneous heart rate with a predetermined threshold, and allows the reduction of the atrio-ventricular delay only when the instantaneous heart rate is below this predetermined threshold, and gradually increases the atrio-ventricular delay as the instantaneous heart rate increases above the threshold.

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 improved active implantable medical device which detects spontaneous atrial and ventricular events, the presence or the absence of an atrio-ventricular spontaneous conduction, and stimulates the atrium and the ventricle, an automatic mode switching operation as between, e.g., DDD and AAI operating modes, for cardiac pacing, which device also includes an activity sensor to discriminate between phases of effort and rest of the patient, and measures the conduction time separating a spontaneous or stimulated atrial event, and a consecutive corresponding spontaneous ventricular event, and provides for a diagnosis of a good or a bad adaptation of the conduction time during the effort phase of the patient. The diagnosis of a good or bad adaptation is performed by an evaluation, during the effort, of the variation of the conduction time in relation to the variation of the heart rate.

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, especially a cardiac pacemaker, defibrillator and/or cardiovertor, of the configurable multisite type. In this multisite device, electrodes are placed in at least three distinct myocardial sites for stimulation (12, 14, 20, 22), of which at least one is a site for ventricular stimulation/detection (14, 22), these electrodes being connected to independent outputs (DA, DV, Da1, Dv2) of the multisite device in a manner as to allow the application of stimulation pulses produced by a plurality of distinct stimulation stages (24, 26, 28, 30). The number of stimulation output stages is at most equal to the number of stimulation sites. The device also includes switches (SA, SV, S1, S2) to connect selectively and according to one of various possible stimulation configurations, the stimulation stages, or selected ones of the stimulation stages, to the various sites of stimulation, or to selected ones of the stimulation sites.

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: 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, particularly of the cardiac pacemaker, defibrillator and/or cardiovertor type, having a function of dual chamber cardiac stimulation and a mode of fallback in which a mode of de-synchronisation of the ventricular stimulation occurs when the atrial rhythm exceeds an acceptable level, and a mode of progressive re-synchronisation occurs in the case of a return of the atrial rhythm to the acceptable level. The re-synchronisation is controlled in a conditional manner to be triggered and maintained only if (a) one detects no trouble of the atrial rhythm. In an alternate embodiment the re-synchronisation is triggered and maintained only if, in addition to condition (a): (b) one detects (20) the presence of an effective sinus rhythm.

Abstract: A rate-adaptive implantable cardiac pacemaker having a control parameter representative of the physical activity of the patient. The change of the stimulation frequency follows, in a manner to reproduce the natural change of the physiological cardiac rhythm, a non-linear mathematical function of time, e.g., of the type:Fc(t)=A*(1-B*e.sup.-t/Tau)+C,in which t is time, A, B, C and Tau are constants, and Fc(t) is the stimulation frequency as a function of time. Tau may be a different value for increasing and decreasing frequencies.

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: A process and device to control a cardiac pacemaker enslaved to at least one physiological parameter. The pacemaker also possesses a mode of desynchronization of the ventricular stimulation when the atrial rhythm is too rapid for synchronous operation. One compares a detected coupling interval (PP) with an escape interval calculated by the enslavement (EI.sub.ASSERV). The calculated enslavement escape interval is preferably decreased by a prematurity factor (x), for example, 0 to 50%, preferably approximately 37.5%, of the calculated escape interval. After the comparison, one counts the number of cardiac cycles for which the coupling interval detected is less than the calculated escape interval, and one triggers the mode of desynchronization (FALLBACK) when the count exceeds a given threshold (y), for example 50 to 75%, preferably approximately 75% of the total number (N) of cardiac cycles analyzed.