Abstract: A pyroelectric suppressor circuit for preventing undesirable thermally induced signals generated by a piezoelectric physical activity sensor from reaching processor circuitry within an implantable medical device is provided. The thermally induced signals typically have frequencies below a frequency in the range from about 0.1 mHz to about 10 mHz. The suppressor circuit provides a high-pass filter that rejects signals that have frequencies associated with thermally induced signals. Signals having frequencies greater than a frequency in the range from about 0.1 mHz to about 10 mHz, which correspond to patient activity, are passed on to processing circuitry of the implantable medical device.

Abstract: An implantable pacemaker continuously records pacing events and their respective rates of occurrence in sequence, as they occur, into an Event Record stored in a circular buffer. The circular buffer always contains the most recent events and rates collected. The recording of the pacing events selectively occurs at every event, or at sampling rates of one event per fixed sample interval. A programming device, coupled to the implantable pacemaker through a telemetry link, selectively retrieves the recorded pacing events and rates from the Event Record and reports subsets thereof in condensed or summarized form using numerical and/or graphical formats. The pacing event data collected in the Event Record is three-dimensional in that each pacing event includes a pacemaker event, an associated pacemaker or heart rate, and a real time interval. The programming device also calculates and reports statistical information from the data collected in the Event Record.

Abstract: An implantable pacemaker continuously records pacing events and their respective rates of occurrence in sequence, as they occur, into an Event Record stored in a circular buffer. The circular buffer always contains the most recent events and rates collected. The recording of the pacing events selectively occurs at every event, or at sampling rates of one event per fixed sample interval. A programming device, coupled to the implantable pacemaker through a telemetry link, selectively retrieves the recorded pacing events and rates from the Event Record and reports subsets thereof in condensed or summarized form using numerical and/or graphical formats. The pacing event data collected in the Event Record is three-dimensional in that each pacing event includes a pacemaker event, an associated pacemaker or heart rate, and a real time interval. The programming device also calculates and reports statistical information from the data collected in the Event Record.

Abstract: A processing system and method are provided for deriving an improved hemodynamic indicator from cardiac wall acceleration signals. The cardiac wall acceleration signals are provided by a cardiac wall motion sensor that responds to cardiac mechanical activity. The cardiac wall acceleration signals are integrated over time to derive cardiac wall velocity signals, which are further integrated over time to derive cardiac wall displacement signals. The cardiac wall displacement signals correlate to known hemodynamic indicators, and are shown to be strongly suggestive of hemodynamic performance. An implantable cardiac stimulating device which uses cardiac wall displacement signals to detect and discriminate cardiac arrhythmias is also provided.

Abstract: An intelligent patch electrode having a plurality of sensor electrodes for use with an implantable defibrillator. The sensor electrodes are disposed in an array and connected to a microcircuit to sense a depolarization wave as it propagates through the ventricular tissue. The timing, direction of propagation, and point of initiation of successive depolarization waves can also be monitored.

Abstract: During the telemetering of telemetry signals between an implantable medical device and an external programmer, the transmitter power of the implantable device is dynamically adjusted. The programmer measures the strength of the telemetry signals transmitted by the implantable device. A power control signal is generated as a function of the measured signal strength, and the transmitter power of the implantable device is set to a power level specified by the power control signal. For example, if the measured signal strength falls below a predetermined minimum signal strength threshold, power must be increased. This process is repeated until the measured signal strength satisfies a predetermined signal strength condition.

Abstract: A movable self-locking suture sleeve which can be securely positioned on the lead body of a pacing lead. The self-locking suture sleeve includes first and second cooperative rigid elements interconnected by a flexible tubing element. The tubing element is constructed from a woven mesh designed to constrict when stretched. A resilient element or spring is interposed between the first and second cooperative rigid elements, tending to force the cooperative rigid elements axially apart. Once the suture sleeve is moved into position, a self-locking feature allows the suture sleeve to secure itself to the lead body.

Abstract: An implantable pacing lead having a flexible insulative material injected into the passageway accommodating the electrical conductor(s) to encapsulate the conductor(s) for at least the portion of the lead body most subject to physical damage to in the lead body.

Abstract: A system and method for safely altering the function of an implanted pacemaker in a noninvasive manner includes an implantable programmable pacemaker and a non-implantable programming device. The pacemaker includes a pulse generator that generates stimulation pulses as controlled by a control program. The control program, and associated control parameters, are stored in an implantable memory included within the pacemaker. The pacemaker further includes a telemetry circuit that allows the control parameters to be selectively changed or altered from a location remote from the pacemaker (i.e., a non-implanted location). The programmer includes a telemetry head for establishing a telemetry link with the pacemaker's telemetry circuit. Once a telemetry link is established, the programmer may be selectively operated to download a new control program into the pacemaker memory, thereby replacing the old control program previously stored in the pacemaker memory.

Abstract: A programming system is provided in which a control program for an implantable medical device is constructed from program modules that are selected by a physician. Only the selected modules are loaded into the memory of the implantable medical device, each one of which provides the control functions necessary to provide a different therapy or diagnostic function. Because a physician typically does not need to elect all of the available therapies or diagnostic routines, the resulting control program may be smaller than a general purpose program designed to implement all of the possible treatments to a patient. Further, a greater selection of therapies and diagnostic routines may be provided, without necessitating an increase in the memory capacity of the implantable medical device.

Abstract: A lead, for use in combination with an implanted pulse generator which may be a pacemaker or defibrillator or combination thereof. The lead can deliver an electrical charge to pace, cardiovert or defibrillate the heart, and can sense cardiac activity in the heart. The lead may include additional sensor electrodes capable of sensing electrical or physical activity in the atrial cavity. The lead allows cardioversion and/or defibrillation stimuli to be provided by a large surface area electrode which is passively implanted in the ventricle, to allow the pulse generator to provide appropriately synchronized atrial-ventricular pacing, cardioversion or defibrillation.

Abstract: An implantable pacemaker continuously records pacing events and their respective rates of occurrence in sequence, as they occur, into an Event Record stored in a circular buffer. The circular buffer always contains the most recent events and rates collected. The recording of the pacing events selectively occurs at every event, or at sampling rates of one event per fixed sample interval. A programming device, coupled to the implantable pacemaker through a telemetry link, selectively retrieves the recorded pacing events and rates from the Event Record and reports subsets thereof in condensed or summarized form using numerical and/or graphical formats. The pacing event data collected in the Event Record is three-dimensional in that each pacing event includes a pacemaker event, an associated pacemaker or heart rate, and a real time interval. The programming device also calculates and reports statistical information from the data collected in the Event Record.

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 dual-chamber pacemaker provides DDI pacing with PVC-protected hysteresis and automatic AV interval adjustment. An extended hysteresis atrial escape interval (AEI.sub.H) is invoked in response to the occurrence of either an atrial paced event followed by a sensed R-wave (an AR event), or an atrial sensed event followed by a sensed R-wave (a PR event). The occurrence of a premature ventricular contraction (PVC) thus does not trigger AEI.sub.H. In one embodiment, AEI.sub.H is not invoked unless the sensed AR or PR interval exceeds a prescribed reference interval. In a further embodiment, the AV interval (AVI) associated with the DDI operation is automatically shortened following an atrial stimulation pulse (A-pulse) delivered upon the timing-out of the AEI.sub.H. The shortened AVI is maintained for a programmed number of cycles of DDI operation, after which a lengthened AVI is reestablished for one cycle.

Abstract: A lead for delivering electrical stimulation pulses to pace the cardiac muscle and for sensing electrical signals occurring in the cardiac muscle is disclosed which as a rigid helix disposed at the extreme distal end thereof which rigid helix may be operated by the implanting physical to extend the tip of the rigid helix from a stored position within the distal end of the lead to a deployed position projecting from the distal end of the lead. The rigid helix pierces and engages the heart tissue to anchor the lead in place within the heart. The tip of the rigid helix has an axial bore therein which is filled with a therapeutic medication such as a steroid or steroid-based drug for inhibiting inflammation and promoting tissue growth. After the tip of the helical screw is disposed in the heart tissue, the therapeutic medication will be slowly eluted into the surrounding tissue, thereby minimizing the trauma of implantation and assisting in the anchoring of the lead.