Abstract: A bus system is provided for implantable medical devices. The bus system provides for flexible and reliable communication between subsystems in an implantable medical device. The bus system facilitates a wide variety of communications between various subsystems. These various subsystems can include one or more sensing devices, processors, data storage devices, patient alert devices, power management devices, signal processing and other devices implemented to perform a variety of different functions.

Abstract: A bus system is provided for implantable medical devices. The bus system provides for flexible and reliable communication between subsystems in an implantable medical device. The bus system facilitates a wide variety of communications between various subsystems. These various subsystems can include one or more sensing devices, processors, data storage devices, patient alert devices, power management devices, signal processing and other devices implemented to perform a variety of different functions.

Abstract: A method and device for transmitting a signal in an implantable medical device that includes a control unit and a first electrode and a second electrode positioned along a lead body. A connector block is positioned along an upper portion of a housing portion of the control unit, and a connector is positioned at a proximal portion of the lead body and is insertable within the connector block. A third electrode having a conductive element is positioned along the control unit in close proximity adjacent to the connector. The control unit transmits a signal between the first electrode and the second electrode and determines an alternate transmission path of the signal between the third electrode and one or both of the first electrode and the second electrode in response to the signal not being effectively transmitted between the first electrode and the second electrode.

Abstract: A method and device for transmitting a signal in an implantable medical device that includes a control unit and a first electrode and a second electrode positioned along a lead body. A connector block is positioned along an upper portion of a housing portion of the control unit, and a connector is positioned at a proximal portion of the lead body and is insertable within the connector block. A third electrode having a conductive element is positioned along the control unit in close proximity adjacent to the connector. The control unit transmits a signal between the first electrode and the second electrode and determines an alternate transmission path of the signal between the third electrode and one or both of the first electrode and the second electrode in response to the signal not being effectively transmitted between the first electrode and the second electrode.

Abstract: A tiered therapy cardiac detection system is provided for a medical device that senses cardiac signals representative of beat-to-beat intervals and delivers at least one therapy in response to a detected cardiac dysrhythmia corresponding to one of a plurality of programmed zones of heart rates. The detection system includes a global counter that counts at least all beat-to-beat intervals indicating a rate greater than a programmed threshold value representative of a minimum heart rate for delivering any therapy once an initial threshold condition is met. A plurality of window memories and parameter memories are provided in the device. Each window memory corresponds to a given one of the zones and stores an indication of whether each of a last N cardiac signals are within that zone. Each parameter memory corresponds to a given one of the zones and stores a programmed trigger value of the global counter required in order for a therapy in that zone to be delivered.

Abstract: An apparatus effectively removes after potential occurring after a electrical pulse is delivered in a cardiac rhythm management system such as a pacemaker system or cardioverter/defibrillator system having an electrode used for both sensing electrical activity of the heart and carrying the electrical pulse to the heart and a sense amplifier for detecting the electrical activity from the electrode. The apparatus includes a lowpass filter coupled to the electrode to filter the sensed electrical activity. A highpass filter is coupled between the lowpass filter and the sense amplifier to further filter the electrical activity passed from the lowpass filter. Equilibrium circuitry is included to allow passive filter components of the lowpass filter and the highpass filter to return to an equilibrium state following delivery of the electrical pulse.

Abstract: A system and method automatically controls a gain of a cardioverter/defibrillator which receives electrical activity of the heart and delivers shock pulses in response thereto. An amplifier amplifies the electrical activity according to a variable gain. A detection circuit detects depolarizations in the amplified electrical activity and provides a detect signal representing a cardiac event indicative of a depolarization when the amplified electrical activity exceeds a sensitivity threshold. A storage device stores peak history information representative of peak values of the amplified electrical activity of a first selected number (N) of cardiac events. Slow gain control circuitry adjusts the variable gain in discrete steps based on the stored peak history information.

Abstract: A system and method automatically adjusts a sensing threshold in a cardioverter/defibrillator which receives electrical activity of the heart and delivers shock pulses in response thereto. An amplifier amplifies the electrical activity. A detection circuit detects depolarizations in the amplified electrical activity and provides a detect signal representing a cardiac event indicative of a depolarization when the amplified electrical activity exceeds a variable sensing threshold. Digital template generation circuitry responds quickly to track amplitudes of the electrical activity and to set the variable sensing threshold to a level proportional to a peak value of the amplitude of the amplified electrical activity and then decreases the variable sensing threshold from the level in discrete steps until the variable sensing threshold is at a low threshold value. The discrete steps are grouped into step groups. Each step group decreases the variable sensing threshold by a defined percentage.

Abstract: A system and method automatically adjusts a sensing threshold in a cardioverter/defibrillator which receives electrical activity of the heart and delivers shock pulses in response thereto. An amplifier amplifies the electrical activity according to a variable gain. A detection circuit detects depolarizations in the amplified electrical activity and provides a detect signal representing a cardiac event indicative of a depolarization when the amplified electrical activity exceeds a variable sensing threshold. Slow gain control circuitry adjusts the variable gain in discrete steps based on stored peak history information representing peak values of the amplified electrical activity. Template generation circuitry responds quickly to set the variable sensing threshold to a level proportional to a peak value of the amplitude of the amplified electrical activity and then decreases the variable sensing threshold from the level in discrete steps until the variable sensing threshold is at a low threshold value.