Abstract: An active implantable medical device of the defibrillator/cardioverter type for the defibrillation or cardioversion of the atrium. The device is able to detect ventricular activity and to deliver conventional low energy ventricular stimulation pulses to the ventricle. It also delivers shock energy pulses having an energy level sufficient to achieve defibrillation and/or cardioversion. The atrial activity is detected to determine the moment at which the shock energy pulse can be delivered to the atrium. The device also recognizes when a ventricular depolarization occurs, and uses this event to control in a conditional manner the delivery of shock energy pulses. More particularly, shock energy pulses are delivered only when the detected ventricular activity indicates the occurrence of a ventricular depolarization following delivery of a ventricular stimulation pulse.

Abstract: An active implanted medical device of the implantable defibrillatory cardioverter type. This device comprises an atrial electrode (40), a ventricular electrode (50), at least one electrode external to the heart (70, 80) and a pulse generator (60). The pulse generator comprises a means for delivering a shock energy pulse for defibrillation or cardioversion, and means for switching the electrode configuration, that determines between which electrodes the defibrillation or cardioversion shock energy pulse is to be applied. The switching means operates in response to the determined delivery of a cardioversion shock pulse energy, by disconnecting the atrial electrode from the means for delivering the shock energy pulse for defibrillation or cardioversion, and, if the configuration of electrodes determined by the switching means foresees the commutation of the atrial electrodes a return electrode, then to substitute for the atrial electrode at least one of electrodes external to the heart.

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: A test circuit and method for the integrity of electrode cables of a typical Holter machine for the recording of physiological signals, notably cardiac activity. This machine comprises: a plurality of signal terminals (16), which are ready to be connected each to a proximal extremity (20) of a cable (18) whose distal extremity (22) is connected to an external electrode (24) to be placed on the patient; amplifiers (30) receiving signals applied on the signal terminals; and circuit means for testing the integrity of the totality of electrical connections to the patient, comprising a current source (36), means (38, 40) to apply this current on terminals and means (34) to measure the voltage drop produced by the impedance of the circuit path (42) including the cable connected to the corresponding terminal and in which circulates the test current.

Abstract: A device for the reception of signals emitted by an active implanted medical device. The device has a signal collector coil for the reception of a magnetic induction which receives a useful signal component (B.sub.s) emitted by the implanted device (26) and a parasitic signal component (B.sub.p) of external origin. There is at least one collecting coil (12) wound on a first portion (14) of a magnetic circuit and at least one compensation coil (22) wound on a second portion (20) of the magnetic circuit, the two portions of the magnetic circuit belonging to a common magnetic element (16) and being configured in a manner such that, when the device is disposed in face of the implanted device, the collecting coil is essentially crossed one time by the magnetic induction field lines of the useful signal component (B.sub.

Abstract: Process and kit for passivating in situ a tip of a probe for an active implantable medical device, particularly for a cardiac pacemaker probe. The probe (10) is of the type comprising a hollow insulating sheath (12) made of a supple material having an internal conductor (14) terminated at its distal extremity by an electrode (16), an axial canal (18) along its length, and a support element (22) at its distal extremity in the neighborhood of the electrode, particularly a metallic filament or blade for shaping or reinforcing the distal extremity (20) of the probe. The support element is of a rigidity that is greater than the combination of the sheath and the internal conductor.

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: Apparatus and methods for adjusting an electrical parameter of an electronic device, notably of an active implantable medical device such as a pacemaker or cardiac defibrillator, and an implementing monolithic integrated circuit for conducting the adjustment.

Abstract: A process to configure an implantable active medical device by adjusting a parameter. For each parameter to be adjusted, the steps of the process are: the determination of a code of adjustment for a given parameter value, writing of the code of adjustment to alter a circuit configuration, and the verification of the validity of the set code. A verified code is then permanently written by straining of selected diodes. The code of adjustment is thus used to adjust a circuit configuration to alter the sensed operating parameter value so that, after straining, the adjusted parameter value of the configured circuit falls in or at a desired range or value. Suitable circuit parameters include clock frequency and reference voltage levels, as are found in cardiac pacemakers and defibrillators.

Abstract: Process and apparatus for extracting a useful signal emitted by an implanted active medical device in the presence of parasitic signals. This device includes a plurality of signal receivers located at distinct points. The signal receivers are sensitive to the magnetic component of the electromagnetic signals and separated from each other by a distance that is negligible as compared to the wavelength of the electromagnetic signal. A plurality of amplifiers are provided with one amplifier being associated with each signal receiver and each amplifier having an adjustable gain. The amplified signals are summed by an adder, and the summed signal (V(t)) is evaluated using a magnitude (.vertline.V.vertline.) representative of the level of the summed signal.

Abstract: A programmable interface for typical Holter machine for recording a physiological signal, notably of cardiac activity. This apparatus (10) comprises the normal plugs (14) for connection to external electrodes and a processing circuit (20) for acquiring and recording the physiological signal, and a programmable interface comprising: at least one voltage supply plug (and preferably two supply plugs V+, V-), at least one ground plug, at least one digital plug (preferably two or more digital plugs D1, D2), cooperating with the processing circuit (20), at least one analog/digital mixed plug (A/D3), on the one hand connected to an analog signal input of the machine, and on the other hand cooperating with the aforementioned processor circuit, and a logic circuit (28) for programming the interface to transfer signals through the plugs of the interface.

Abstract: An active implantable medical device, particularly a cardiac pacemaker or defibrillator, having a protection circuit that is effective against electromagnetic perturbations of external origin. The active implantable device is characterized in that at least all active components of the protection circuit (58, 60, 94, 98) are integrated components in a monolithically integrated microchip (16) including a control signal and circuits to commute selectively signals collected by external electrodes to the device for processing. In particular, the commutation circuits comprise static switches (24, 24', 28, 28', 38, 38', 40, 40', 44, 44', 46, 46', 50, 50', 54), and the control signal is a control voltage (VSUB, VCC) that is greater than the voltage (VPILE) of the battery of the device.

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 of physiological data compression, notably cardiac activity, especially for a recording of an electrocardiogram or a Holter electrogram. This process is characterized by the following successive operations: (a) acquisition of data by collection of an electrical signal and sampling of this signal at a given frequency; (b) determination of the first derivative of the sampled signal; (c) determination of the second derivative of the sampled signal; (d) analyze predictively the sampled signal according to a plurality of values of first and second derivatives and selection, for the current sample, of a mode of coding from among a plurality of predetermined coding modes which are commutable dynamically, in a manner to optimize the global code volume created for coding the aforementioned plurality of future values; and (e) compression of data by the implementation of the coding mode chosen at stage (d). Decompression occurs by the inverse of the compression mode of coding.

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.

Abstract: The invention protects circuits connected to low energy stimulating (pacing) or detection (sensing) electrodes of an implantable medical device from high energy pulses generated by the device itself or by external devices such as external defibrillators. It also protects cardiac tissue near the low energy electrodes. The invention provides for an automatic and/or foldback-type unidirectional current limiter in each low energy lead. The invention, when applied to an implantable defibrillator/pacemaker, also provides a shock generator presenting pulses to the pacing electrodes only in the direction blocked by the current limiter.

Abstract: Control of a double atrial triple chamber cardiac pacemaker having a programmable fallback mode. The triple chamber pacemaker has a right atrial electrode and a left atrial electrode connected to the same atrial detection/stimulation circuit, as well as a ventricular electrode connected to a ventricular detection/stimulation circuit of the pacemaker. The fallback mode involves desynchronization of the ventricular stimulation from the detected atrial rhythm when the atrial rhythm is too rapid. The pacemaker also includes a fallup mode of pacing in which there is a progressive re-synchronization of ventricular stimulation to the atrial rhythm when the atrial rhythm falls to a less rapid rhythm.