Abstract: An implantable dual chamber stimulation device provides a novel detection scheme for automatically detecting atrial capture and performing an atrial pacing threshold assessment. The stimulation device preferably waits until the patient is at or near rest and monitors the patient's P-wave activity to determine an detection window where a next P-wave is expected to occur. The stimulation device then delivers an atrial pulse prior to the next detection window, and monitors the window to determine whether a P-wave occurs therein. If a P-wave does not occur, then atrial capture is present, while occurrence of a P-wave indicates absence of atrial capture. If atrial capture is absent, the stimulation device automatically determines an appropriate atrial pacing threshold by monitoring the detection window while adjusting the stimulation pulse energy level.

Abstract: An implantable medical device provides atrial arrhythmia prevention pacing when an interatrial conduction disturbance is detected. The implantable medical device includes a signal processor that detects the interatrial conduction disturbance and a pulse generator circuit coupled to the detector that delivers the atrial arrhythmia prevention pacing pulses to the heart when the processor detects the interatrial conduction disturbance. The interatrial conduction disturbance may be a P-wave duration, a difference between odd and even P-waves, or a predetermined P-wave spectral energy distribution.

Abstract: A pacemaker programmer and diagnostic system retrieves information stored within a pacemaker and analyzes the retrieved data in real time. The stored information can be retrieved by means of a telemetry communication link. The pacemaker automatically lengthens a post-ventricular atrial refractory period (PVARP). The pacemaker determines atrial capture threshold by generating atrial stimulation pulses while maintaining the ventricular stimulation pulse amplitude at a level known to ensure ventricular capture, and by detecting loss of atrial capture. In response to the loss of atrial capture, a processor automatically shortens the AV delay in a subsequent cardiac cycle, to reduce the possibility of a retrograde P-wave initiating a pacemaker-mediated tachycardia (PMT). Also in response to the loss of atrial capture, the pacemaker records the atrial capture threshold, restores the PVARP to its pre-test value, and sets the atrial stimulation pulse amplitude to a value above the atrial capture threshold.

Abstract: A pacemaker programmer and diagnostic system retrieves information stored within a pacemaker and analyzes the retrieved data in real time. The stored information can be retrieved by means of a telemetry communication link. The pacemaker automatically lengthens a post-ventricular atrial refractory period (PVARP). The pacemaker determines atrial capture threshold by generating atrial stimulation pulses while maintaining the ventricular stimulation pulse amplitude at a level known to ensure ventricular capture, and by detecting loss of atrial capture. In response to loss of atrial capture, a processor automatically triggers a premature ventricular contraction (PVC) response to prevent a retrograde P-wave from initiating a pacemaker-mediated tachycardia. Also in response to loss of atrial capture, the processor sets the atrial stimulation pulse amplitude to a value above the atrial capture threshold in a subsequent cardiac cycle, and restores the PVARP to its pre-test value.

Abstract: A device in the form of a cardiac pacemaker for treating a malfunctioning heart, in which the intrinsic heart rate information is combined with secondary sensor variance information to select an appropriate therapy for the patient. The cardiac pacemaker has operational capability in the sleep mode and includes a hysteresis function. The hysteresis function is disabled during operation in the sleep mode and a pacing therapy is selected based upon the intrinsic heart rate and sleep mode operation.

Abstract: A pacemaker programmer and diagnostic system retrieves information stored within a pacemaker and analyzes the retrieved data in real time. The stored information can be retrieved by means of a telemetry communication link. The pacemaker automatically lengthens an AV delay. The pacemaker determines atrial capture by generating atrial stimulation pulses while maintaining the ventricular stimulation pulse amplitude at a level known to ensure ventricular capture, and by detecting loss of atrial capture. In response to the loss of atrial capture, a processor automatically records the atrial capture threshold, and restores the AV delay to its pre-test value. The pulse generator also delivers a backup atrial stimulation pulse concurrent with a ventricular stimulation pulse to reduce the possibility of a retrograde P-wave initiating a pacemaker-mediated tachycardia (PMT).

Abstract: An apparatus for protecting the gate of an animal enclosure with an electrified wire that also extends along fencing includes a reel that dispenses and collects the wire to minimize the possibility of shock during gate opening and closing procedures. A hollow reel housing is mounted to a first fence post to which the gate is hingedly attached. A truncate wire connected to a source of electrical power such as an electrified fence wire extends into the hollow reel housing through a first opening and is connected to a nonrotating electrical contact. An annular rotating electrical contact is in electrical communication with a proximal end of wire coiled about the reel and is mounted on the reel so that the wire remains in electrical communication with the source of power when the reel is rotating in a wire-dispensing direction or in a wire-collecting direction. The wire, when uncoiled, extends through a second opening formed in the hollow reel housing.

Abstract: A pacemaker programmer and diagnostic system retrieves information stored within a pacemaker and analyzes the retrieved data in real time. The stored information can be retrieved by means of a telemetry communication link. The pacemaker automatically lengthens a post-ventricular atrial refractory period (PVARP). The pacemaker determines atrial capture by generating atrial stimulation pulses while maintaining the ventricular stimulation pulse amplitude at a level known to ensure ventricular capture, and by detecting loss of atrial capture. In response to loss of atrial capture, a processor automatically records the atrial capture threshold, and restores the PVARP and the atrial pulse amplitude to their pre-test values.

Abstract: An implantable cardiac device, such as a pacemaker or an implantable cardioverter-defibrillator that has a control unit which is adapted to sample a time-varying parameter relating to either the patient's changing physiological condition or to the delivery of therapeutic electrical stimulation pulse to the heart at a sampling frequency. The control unit is adapted to increase the sampling frequency when the variation between successive measurements of the parameter exceed a preselected value. The control unit is further adapted to decrease the sampling frequency when the variation between successive measurements of the parameter are less than a preselected value. In alternate embodiments, the parameter to be sampled is capture threshold, sensing threshold, lead-tissue impedance, and battery performance.

Abstract: A special type of AV/PV hysteresis is provided in a dual-chamber pacemaker. A long AV delay is initially provided, thereby affording as much opportunity as possible for natural AV conduction to occur. Such long AV delay is automatically shortened should AV block occur. Periodic scanning for the return of AV conduction (absence of AV block) is performed so that the AV delay can be returned to its long value as soon as possible. In one embodiment, the pacemaker "learns" the natural conduction time (AR interval) of the patient and thereafter uses such learned natural conduction time as a reference against which subsequently measured AR intervals are compared to better distinguish conducted ventricular contractions from ectopic, pathologic, or other nonconducted ventricular contractions (e.g., PVC's).

Abstract: A dual-chamber implantable pacemaker is configured to operate in the DDD or DDDR mode with its AV (or PV) interval automatically set to be a small time interval less than the natural conduction time of a patient. The pacemaker shortens the AV (or PV) interval in response to a verified R-wave occurring within the AV (PV) interval, which it discriminates from an ectopic R-wave by requiring the occurrence of at least three consecutive R-waves or, alternatively, the occurrence of an R-wave having a morphology that matches the morphology of a reference R-wave stored in the pacemaker's memory. When the AV (or PV) interval is set to a value that is less than the natural conduction time, preemptive ventricular pacing.

Abstract: Preemptive tachyarrhythmia pacing is provided in an implantable cardiac-stimulation device, such as an implantable pacemaker or defibrillator, by modifying the operation of the implantable device in a way that minimizes the likelihood of occurrence of a tachyarrhythmia. The behavior modification is achieved through the use of an appropriate preemptive tachyarrhythmia pacing control routine stored within the memory of the device. Depending upon the needs of the patient, preemptive tachyarrhythmia pacing is invoked continuously or on demand. If invoked on demand, Preemptive tachyarrhythmia pacing is triggered only upon the sensing of one or more conditions suggest that the onset of a tachyarrhythmia is imminent. When thus invoked, preemptive tachyarrhythmia pacing remains invoked only for as long as the onset-of-a-tachyarrhythmia-is-imminent conditions persist.

Abstract: An implantable dual-chamber pacemaker programmed to operate primarily in a P-wave tracking mode, where the pacemaker switches to a fallback response at a threshold rate higher than a maximum tracking rate of the pacemaker. When the fallback response is initiated the ventricular pacing rate is progressively reduced to a fallback rate. The pacemaker exits the fallback response when programmable fallback exit criteria are met.

Abstract: An improved pacemaker programmer and diagnostic system retrieves information stored within a pacemaker and analyzes the retrieved data in real time. The information stored within the pacemaker can be retrieved by means of a telemetry communication link. The system automatically identifies significant patient events (such as regions of increased heart rate, or loss of atrial or ventricular capture) and displays the significant events to the monitoring physician so that the physician is not required to scroll through the retrieved data to identify significant events. Furthermore, the system automatically suggests modifications to pacemaker parameters based upon certain retrieved data. The physician need only confirm the changes in order to modify the parameters within the pacemaker, so that the modification of pacemaker parameters is reduced to a "one step" process.

Abstract: A special type of AV/PV hysteresis is provided in a dual-chamber pacemaker. A long AV delay is initially provided, thereby affording as much opportunity as possible for natural AV conduction to occur. Such long AV delay is automatically shortened should AV block occur. Periodic scanning for the return of AV conduction (absence of AV block) is performed so that the AV delay can be returned to its long value as soon as possible. In one embodiment, the pacemaker "learns" the natural conduction time (AR interval) of the patient and thereafter uses such learned natural conduction time as a reference against which subsequently measured AR intervals are compared to better distinguish conducted ventricular contractions from ectopic, pathologic, or other nonconducted ventricular contractions (e.g., PVC's).

Abstract: A special type of AV/PV hysteresis is provided in a dual-chamber pacemaker. A long AV delay is initially provided, thereby affording as much opportunity as possible for natural AV conduction to occur. Such long AV delay is automatically shortened should AV block occur. Periodic scanning for the return of AV conduction (absence of AV block) is performed so that the AV delay can be returned to its long value as soon as possible. In one embodiment, the pacemaker "learns" the natural conduction time (AR interval) of the patient and thereafter uses such learned natural conduction time as a reference against which subsequently measured AR intervals are compared to better distinguish conducted ventricular contractions from ectopic, pathologic, or other nonconducted ventricular contractions (e.g., PVC's).

Abstract: Methods and apparatus are provided for alleviating the effects of crosstalk in an implantable stimulation device. An autoblanking approach is provided whereby the total blanking interval is made up of an absolute blanking interval followed by a retriggerable relative blanking interval. The implantable stimulation device sensing circuitry is disabled during the absolute blanking interval and enabled during the relative blanking intervals. If a signal is detected during a relative blanking interval, a successive relative blanking interval is initiated. If no signal is detected, then relative blanking terminates. Further, an approach for combining safety standby pacing with autoblanking is provided. If autoblanking terminates before the crosstalk sensing interval reaches a maximum blanking interval, then safety standby pacing is cancelled. Another aspect of the invention relates to monitoring the amount of time in a safety standby sensing window during which signals are detected.

Abstract: An implantable dual-chamber pacemaker programmed to operate primarily in an atrial tracking mode is provided, where the pacemaker includes an atrial rate smoothing filter for producing a filtered atrial rate from an intrinsic atrial rate, and where the pacemaker automatically switches its mode of operation from the atrial tracking mode to a non-atrial tracking mode in the event the filtered atrial rate exceeds a prescribed upper rate limit. The pacemaker switches from a primary set of operational parameter settings for the primary mode, to an alternate set of operational parameters for the alternate mode when the mode is switched from the primary mode to the alternate mode. The pacemaker also includes the capability of recording and storing mode switching events and data pertaining to the mode switching events.

Abstract: A programming system is provided that allows a physician or medical personnel to optimize the settings of various arrhythmia detection criteria and/or parameters related to hemodynamic performance to be programmed into the implanted cardiac stimulating device. The cardiac stimulating device may be a pacemaker or cardioverter/defibrillator that detects heart arrhythmias by using various arrhythmia detection criteria. The cardiac stimulating device is capable of recording the patient's cardiac signals and/or sensor data. The programming system may play back the recorded signals to test the detection criteria and hemodynamic performance and may simulate the response of the device to the cardiac signal. Alternatively, the programming system may play back an artificially created or previously stored cardiac signal for test purposes. As a result, the recorded signal may be played back repeatedly without unnecessarily stressing the patient's heart.

Abstract: A programming system is provided that allows a physician or medical personnel to optimize the settings of various arrhythmia detection criteria and/or parameters related to hemodynamic performance to be programmed into the implanted cardiac stimulating device. The cardiac stimulating device may be a pacemaker or cardioverter/defibrillator that detects heart arrhythmias by using various arrhythmia detection criteria. The cardiac stimulating device is capable of recording the patient's cardiac signals and/or sensor data. The programming system may play back the recorded signals to test the detection criteria and hemodynamic performance and may simulate the response of the device to the cardiac signal. Alternatively, the programming system may play back an artificially created or previously stored cardiac signal for test purposes. As a result, the recorded signal may be played back repeatedly without unnecessarily stressing the patient's heart.