Abstract: A system and method for automatically adjusting the gain for a shock lead system in an implantable medical device is provided. The system and method operate when, after a pre-selected period of time, the gain has not been programmed. The system and method then automatically produce and set the gain for the shock lead system. The system and method poll and determine a maximum value for the output of the shock lead system amplifier and produce a new gain value to scale the output to facilitate providing useful data that is large enough to separate signal from noise but small enough to avoid clipping.

Abstract: Methods and apparatus for communication of implantable medical device (IMD) information, including interrogation of programmed parameter values, operating modes and conditions of operation, confirmation of programmed changes thereof, interrogation of data stored in the IMD, and patient warnings or other messages by RF transmission of audible sounds generated by the IMD are disclosed. The IMD includes an RF transmitter that broadcasts or transmits audible sounds including voiced statements or musical tones stored in analog memory correlated to a programming or interrogation operating algorithm or to a warning trigger event. The broadcast radio signal is received, and the audible sounds are demodulated and reproduced by a radio receiver as voiced statements or musical tones that convey human understandable messages comprising IMD information generated during programming and interrogation sessions and warnings or status messages to the patient at other.

Abstract: An implantable cardiac pacemaker is adapted to be selectively non-invasively upgraded from time to time after implantation to provide a plurality of different diagnostic, functional, and pacing operational modes in the form of respective combinations of single and dual chamber sensing and pacing and rate-adaptive pacing of a patient's heart to correct any of various cardiac arrhythmias attributable to cardiac pacing or cardiovascular disorders, and of extended memory and physiological monitoring functions. The pacemaker is implemented to make available the plurality of different pacing operational and other functional modes, and is programmable to selectively enable current operation of at least one of the available pacing operational modes according to current needs of the patient while inhibiting current operation of all other available pacing operational modes and any other non-selected functional modes.

Abstract: Methods and apparatus for confirming programming of implantable medical device (IMD) operating parameter values and operating modes by emission of audible sounds by the IMD are disclosed. The IMD includes an audio transducer that emits audible sounds including voiced statements or musical tones stored in analog memory correlated to a programming or interrogation operating algorithm or to a warning trigger event. The audible sounds can comprise the sole uplink transmission or may augment the contemporaneous uplink RF transmission of stored data, and/or programmed operating modes and parameters and/or device operations and states in an interrogation or during programming. To conserve energy, the audible sounds accompanying interrogation and programming of the IMD are at a low volume that preferably cannot be heard without use of an external audio amplifier or stethoscope.

Abstract: Methods and apparatus for confirming programming of implantable medical device (IMD) operating parameter values and operating modes by emission of audible sounds by the IMD are disclosed. The IMD includes an audio transducer that emits audible sounds including voiced statements or musical tones stored in analog memory correlated to a programming or interrogation operating algorithm or to a warning trigger event. The audible sounds can comprise the sole uplink transmission or may augment the contemporaneous uplink RF transmission of stored data, and/or programmed operating modes and parameters and/or device operations and states in an interrogation or during programming. To conserve energy, the audible sounds accompanying interrogation and programming of the IMD are at a low volume that preferably cannot be heard without use of an external audio amplifier or stethoscope.

Abstract: A pacemaker generates and transmits real-time intracardiac electrogram signals to an external display device for display thereon. Simultaneously, the pacemaker senses a variety of events occurring either within the heart tissue or within the pacemaker itself and transmits signals representative of those events for display, using appropriate marker icons, along with the intracardiac electrograms. In this manner, a physician viewing the intracardiac electrograms is simultaneously apprised of the various events. In one example, events displayed along with the intracardiac electrograms include the detection of atrial and ventricular events occurring within the heart during a non-absolute refractory period following generation of a stimulation signal.

Abstract: A device for filtering signals emitted by a medical device, principally an active implanted medical device. The device (26) receives an input that is a signal delivered by a circuit (16-24) that receives signals emitted by a medical device (10) in the form of a magnetic induction, in which the medical device has a metallic housing or case. A compensation stage (42) also is provided, having in the frequency domain a transfer function in the form: ##EQU1## where f.sub.c is a chosen parameter according to the geometry and the material of the metallic case of the medical device (10), and where j=.sqroot.-1. The device is useful with medical devices that emit sequences of messages formed by symbols belonging to an alphabet of n symbols (n.gtoreq.2), the compensation stage being able to reduce the rate of inter-symbol interference of collected signals that are applied to it.

Abstract: An adaptive, performance-optimizing communication system for communicating with an implanted medical device in which signals are transmitted and received in accordance with predetermined, interrelated operational parameters, such as transmission rate, transmitter power, and the like. Various aspects of system performance, including bit error rate in received signals, the strength of received signals, the signal-to-noise ratio of received signals, the presence of local RF noise and non-telemetry related RF signals, and the like, are dynamically monitored by the communication system, to determine whether predetermined system performance goals are being met. If it is determined that one or more system performance goals are not being met, one or more operational parameters may be automatically adjusted so that desired performance can be achieved.

Abstract: An implantable cardioverter/defibrillator device is implemented to be selectively non-invasively upgraded from time to time after implantation to enable the device to provide additional therapy for arrhythmia treatment as the patient's need for such treatment undergoes change. The device is adapted to provide a plurality of functions corresponding to different levels of therapy for treating arrhythmias, and to respond to each different type of arrhythmia that may be sensed, to supply a function which is designated as being appropriate to relieve that respective arrhythmia. Each function is not necessarily unique to treating a particular arrhythmia, and, in at least some instances, may be used to treat more than one of the plurality of different types of arrhythmias. At the time of its implant, the device is restricted from providing those of the plurality of functions which are deemed as being non-essential to the patient's needs at that time.

Abstract: Disclosed are apparatus and method for detecting electromagnetic interference (EMI), or noise, that may disrupt the proper operation of medical devices implantable in patients, such as cardiac stimulators. Circuitry of the detector of the invention is independent of other circuitry of the medical device. EMI is magnetically induced on an antenna that may be within the metal housing of the device in a receiver circuit, and the EMI signals are output to the noise detector. A variety of alert signals may be provided to the medical device circuitry to warn of the presence of EMI so that appropriate responses may be taken to insure the safety of the patient dependent on the device. The detector may share the telemetry antenna of the medical device, or utilize a separate, dedicated antenna to receive EMI. Alternative antennas external to the metal housing of the medical device include leads from the device to the heart of the patient, and a dedicated antenna in the non-metal header of the device.

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: An adaptive, performance-optimizing communication system for communicating with an implanted medical device in which signals are transmitted and received in accordance with predetermined, interrelated operational parameters, such as transmission rate, transmitter power, and the like. Various aspects of system performance, including bit error rate in received signals, the strength of received signals, the signal-to-noise ratio of received signals, the presence of local RF noise and non-telemetry related RF signals, and the like, are dynamically monitored by the communication system, to determine whether predetermined system performance goals are being met. If it is determined that one or more system performance goals are not being met, one or more operational parameters may be automatically adjusted so that desired performance can be achieved.

Abstract: A calibration system for use with an implantable pacemaker allows the intracardiac electrogram (IEGM) generated by the pacemaker to be calibrated when the pacemaker is coupled to an external programmer. The calibration system includes telemetry circuits within both the pacemaker and programmer that allow data signals to be sent from the pacemaker to the programmer, and that allow command signals to be sent from the programmer to the pacemaker, in conventional manner. The system further includes circuitry within the pacemaker that generates a precision reference voltage as well as a zero reference voltage, and that selectively switches the precision reference voltage and/or the zero reference voltage into the IEGM data signals being telemetered to the external programmer from the pacemaker. The switching of the precision reference voltage and/or zero reference voltage into the IEGM data occurs within the pacemaker upon receipt of a special calibration command signal from the programmer.

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: Apparatus and electrical circuitry are provided for electrical devices in order to provide electrical isolation of exposed electrical contacts on at least one of multiple modules of the electrical device. The apparatus includes at least one actuating component in one module and at least one sensor component within a second module in electrical communication with electrical circuitry, whereby electrical isolation of the exposed electrical contacts ceases when the sensor apparatus senses a desired location of the module. Placement of the apparatus and electrical circuitry to reside within the modules promotes electrical safety while minimizing tampering with safety aspects of the device. The apparatus and circuitry are useful for medical devices such as handheld diagnostic devices and consumer devices such as telephones.

Abstract: Reprogramming of implanted pacemakers is made more reliable and secure by utilizing a pad having an adhesive surface provided on its upper and lower contacting layers. In the illustrated embodiment, the pad is generally circular with a central circular hole. The pad is placed over the implanted pacemaker at a predetermined position utilizing the central aperture hole for alignment of the pad on the site of pacemaker implantation. An auxiliary cardiac device, such as a programming head, is then disposed on the upper adhesive of the circular pad. The shape of the pad inherently induces the medical technician to appropriately register the auxiliary device relative to the pacemaker. The double adhesive layers of the pad provide temporary affixation of the auxiliary device relative to the pacemaker during the reprogramming or other pacemaker manipulation so that inadvertent relative movement of the auxiliary device relative to the programmable pacemaker is avoided.

Abstract: Apparatus and electrical circuitry are provided for electrical devices in order to provide electrical isolation of exposed electrical contacts on at least one of multiple modules of the electrical device. The apparatus includes at least one actuating component in one module and at least one sensor component within a second module in electrical communication with electrical circuitry, whereby electrical isolation of the exposed electrical contacts ceases when the sensor apparatus senses a desired location of the module. Placement of the apparatus and electrical circuitry to reside within the modules promotes electrical safety while minimizing tampering with safety aspects of the device. The apparatus and circuitry are useful for medical devices such as handheld diagnostic devices and consumer devices such as telephones.