Abstract: Determining the presence and type of a probe associated with an active implantatable medical device, in particular a cardiac pacemaker and devices having similar pacemaker functionality. This device includes circuits for producing monopolar or bipolar stimulation pulses, selectively with or without disconnection of a connection (S1, S2) to a reference potential, and a circuit for sensing a pulse signal produced by the variation of potential induced on one and/or the other of terminals (RING, TIP) and/or on the metallic case (CASE) in response to an application of stimulation pulses. The device operates to analyze a characteristic of the shape (28), in particular the pulse width, and to deliver an indicator representative of the presence or the absence of a probe. The device also can selectively modify at least one operating parameter of the device according to the delivered indicator.

Abstract: Determining the presence and type of a probe associated with an active implantatable medical device, in particular a cardiac pacemaker and devices having similar pacemaker functionality. This device includes circuits for producing monopolar or bipolar stimulation pulses, selectively with or without disconnection of a connection (S1, S2) to a reference potential, and a circuit for sensing a pulse signal produced by the variation of potential induced on one and/or the other of terminals (RING, TIP) and/or on the metallic case (CASE) in response to an application of stimulation pulses. The device operates to analyze a characteristic of the shape (28), in particular the pulse width, and to deliver an indicator representative of the presence or the absence of a probe. The device also can selectively modify at least one operating parameter of the device according to the delivered indicator.

Abstract: A device for determining the effectiveness of the electrical stimulation of heart muscle from a signal having a post-potential component and, with effective stimulation, a superimposed evoked response component. The device includes a differential stage with a first input for application of the signal and a second input for application of a feedback signal. The differential stage generates a corresponding output signal whose level is determined by the levels of the signals present at the first and said second inputs. A comparator stage has feedback units able to act on the second input in a follower relationship with respect to the signal present at the first input avoiding saturation of the differential stage. The feedback units generate at least one compensation signal indicating the variation in the signal present at the first input over time. The compensation signal is indicative of the evoked response superimposed on the post-potential component.

Abstract: An implantable dual-chamber pacemaker system has a means for automatic beat-to-beat adjustment of the maximum allowable variation (MAV) of the sensed atrial rate (AR) as a function of the sympatho-vagal balance, switching from an atrial tracking mode of operation (e.g., DDD or DDD(R)) to a non atrial tracking mode (e.g., VDI or VDI(R)) when either an arrhythmic tachycardic rate, exceeding the MAV, or a sinus tachycardic rate, exceeding the maximum tracking atrial rate (MTAR), is detected. The pacemaker provides logic means for continuously determining the atrial rate variation (&Dgr;AR) and the MAV. The MAV defines the upper limit for the &Dgr;AR above which tracking is not allowed, discriminating between physiological rate variations and arrhythmic variations. The pacemaker system can return to an atrial tracking mode of operation if the AR remains under a defined rate for a defined number of cycles.

Abstract: An implantable dual-chamber pacemaker system has a means for automatic beat-to-beat adjustment of the maximum allowable variation (MAV) of the sensed atrial rate (AR) as a function of the sympatho-vagal balance, switching from an atrial tracking mode of operation (e.g., DDD or DDD(R)) to a non atrial tracking mode (e.g., VDI or VDI(R)) when either an arrhythmic tachycardic rate, exceeding the MAV, or a sinus tachycardic rate, exceeding the maximum tracking atrial rate (MTAR), is detected. The pacemaker provides logic means for continuously determining the atrial rate variation (&Dgr;AR) and the MAV. The MAV defines the upper limit for the &Dgr;AR above which tracking is not allowed, discriminating between physiological rate variations and arrhythmic variations. The pacemaker system can return to an atrial tracking mode of operation if the AR remains under a defined rate for a defined number of cycles.

Abstract: A device for determining the effectiveness of the electrical stimulation of heart muscle from a signal having a post-potential component and, with effective stimulation, a superimposed evoked response component. The device includes a differential stage with a first input for application of the signal and a second input for application of a feedback signal. The differential stage generates a corresponding output signal whose level is determined by the levels of the signals present at the first and said second inputs. A comparator stage has feedback units able to act on the second input in a follower relationship with respect to the signal present at the first input avoiding saturation of the differential stage. The feedback units generate at least one compensation signal indicating the variation in the signal present at the first input over time. The compensation signal is indicative of the evoked response superimposed on the post-potential component.

Abstract: A buried-resistance semiconductor device is constructed by forming a P-type monocrystalline silicon substrate on which an epitaxial layer of silicon doped with type N impurities is grown, a portion of the epitaxial layer being insulated by a P-type insulating region extending from the substrate to the surface of the epitaxial layer. Two suitably-spaced terminals are secured to the surface of the epitaxial layer in the area bounded by the insulating region. Two separation regions extending into the surface layer are formed in the part of the epitaxial layer between the terminals, and a buried region extends from the substrate between the separation regions without being in contact with them. The three regions are of P-type material, and have an elongated shape and are bounded at the ends by the insulating region.