Abstract: A system and method for determining a remaining life estimate of the remaining battery life of a battery of an implantable medical device (IMD). The IMD battery preferably exhibits a highly reproducible monotonically decreasing discharge curve. The estimated remaining life estimates are derived by periodically measuring battery voltage, and estimating the estimated past current drain of the IMD comprising an average of the sum of the quiescent current drain and therapy delivery current drain, and determining the estimated remaining longevity from the measured voltage and the estimated past current drain.

Abstract: A capture detection algorithm detects and distinguishes atrial capture. Atrial chamber reset (ACR) and AV conduction (AVC) algorithms are implemented to measure an atrial pacing threshold The data that is used to choose between ACR and AVC methods is used to determine the progression of the patient's disease state. Some of the significant aspects of the invention include enablement of accurate threshold measurements, including calculation of stability criteria, precise interval measurements and the use of reference interval to determine capture and loss of capture.

Abstract: A system and method for determining a remaining life estimate of the remaining battery life of a battery of an implantable medical device (IMD). The IMD battery preferably exhibits a highly reproducible monotonically decreasing discharge curve. The estimated remaining life estimates are derived by periodically measuring battery voltage, and estimating the estimated past current drain of the IMD comprising an average of the sum of the quiescent current drain and therapy delivery current drain, and determining the estimated remaining longevity from the measured voltage and the estimated past current drain.

Abstract: A system and method for determining a remaining life estimate of the remaining battery life of a battery of an implantable medical device (IMD). The IMD battery preferably exhibits a highly reproducible monotonically decreasing discharge curve. The estimated remaining life estimates are derived by periodically measuring battery voltage, and estimating the estimated past current drain of the IMD comprising an average of the sum of the quiescent current drain and therapy delivery current drain, and determining the estimated remaining longevity from the measured voltage and the estimated past current drain.

Abstract: An automatic, body-implantable medical device having at least two modes of operation is disclosed. The device is provided with circuitry for automatically detecting when the device has been implanted in a patient, so that the device can automatically switch from a first mode to a second mode of operation upon implantation. In one embodiment, the first mode is a power conserving mode in which one or more non-essential sub-systems of the device are disabled. Prior to detection of implant, at least two conditions of the device known to reflect whether the device has been implanted are monitored. After implant has been detected, situations in which power to the device is disrupted and then restored will cause the device to enter a predefined "power-on-reset" mode of operation. Prior to detection of implant, however, such conditions do not result in the device entering the power-on-reset mode, or this mode is reset.

Abstract: Two mechanisms work together to adjust two variables independently so that the gain of an input amplifier used to find physiologic signals in an implantable medical device can be automatically adjusted to enhance the signal to noise ratio of the electrical input to said amplifier. The first determines whether there has been too long a time between senses found in the body's electrical input to the amplifier and if true, and no other conditions override that consideration, it adjusts the value of a long term average parameter which is used as a referent parameter to adjust the actual parameter that is used as the referent for making either a threshold level adjustment or gain change, depending on the structure of the particular design's circuitry and/or software. One set of adjustments to the gain referent parameter depends on the relative size of the long term average parameter and the gain referent parameter.

Abstract: An automatic, body-implantable medical device having at least two modes of operation is disclosed. The device is provided with circuitry for automatically detecting when the device has been implanted in a patient, so that the device can automatically switch from a first mode to a second mode of operation upon implantation. In one embodiment, the first mode is a power conserving mode in which one or more non-essential sub-systems of the device are disabled. Prior to detection of implant, at least two conditions of the device known to reflect whether the device has been implanted are monitored. After implant has been detected, situations in which power to the device is disrupted and then restored will cause the device to enter a predefined "power-on-reset" mode of operation. Prior to detection of implant, however, such conditions do not result in the device entering the power-on-reset mode, or this mode is reset.

Abstract: An AV search method and apparatus is taught with some variation described. It allows a pacemaker to find the appropriate AV interval so as to avoid pacing in the ventricle when it is not necessary, even if there is intermittent AV conduction in the patient. Also, an adaptive PVARP method and apparatus is disclosed that allows the PVARP and AV interval to be adjusted together automatically.

Abstract: A pacemaker control method and apparatus for determining the presence of atrial tachyarrhythmias uses a true interval value and compares it to a predetermined tachy value. The true interval value is updated based on the presence of far field R waves in PVARP that meet certain sequencing criteria. The criteria selected allows the control method and apparatus to reduce or eliminate event sequences that will generate false positive tachy detection and subsequent mode switching, while still allowing for the detection of tachy events in PVARP.

Abstract: An implantable medical device telemetry system provides a means for decoding telemetry downlink information transmitted from an external unit to an implanted medical device, and for encoding telemetry uplink signals to be transmitted from the implanted device to the external unit. A novel system architecture results in a very small telemetry subsystem in the implanted device and a very flexible system adaptable to be used in conjunction with various telemetry formats of various implanted devices. A programmable logic array (PLA) structure that is mask programmable and which may further be partially RAM programmable serves as the basis of the telemetry subsystem. For downlink telemetry, a counter is enabled during intervals of interest in the downlink RF burst stream. The counter value at the end of such an interval is then applied to the variable inputs of the PLA tier decoding in accordance with a selected telemetry protocol.

Abstract: A method of and apparatus for telemetering both analog and digital data transcutaneously between an implantable medical device and an external receiver, such as between an external programmer and an implantable cardiac pacer. A damped carrier at 175 kilohertz is pulse position modulated by digital data. The data, along with synchronization and identification codes, are positioned into predefined ranges within predefined frames as measured by individual time periods. The data is uniquely identified by the position of a burst of the carrier within the predefined range. An automatically initiated hand shake protocol maintains the link over slight variations in programmer head position with an indicator notifying the operator when repositioning is required. Analog data may be transferred in digital form or alternatively transferred using phase modulation of the carrier bursts. A cyclic redundancy code is used for link error detection.