Abstract: Baroreflex activation is achieved by providing suitable control signals to a baroreflex activation device. A method comprises establishing a therapy interval (possibly on the order of minutes to hours, or possibly of indefinite duration), within the therapy interval, establishing a plurality of dose intervals, and generating an electrical output signal. The electrical output signal has a time dependence such that the average electrical power applied to the baroreflex activation device differs between first and second portions of at least some dose intervals. Another method comprises establishing a series of therapy interval portions, during at least some therapy intervals, establishing a plurality of burst intervals (perhaps having durations commensurate with an interval between heartbeats), and generating an electrical output signal.

Abstract: Methods for improving detection of arrhythmias by adaptively increasing arrhythmia detection intervals. One method includes increasing the V2V, the overall cardiac cycle length, thereby decreasing the pacing rate in the presence of ventricular safety paces (VSPs). Another method includes shortening the trigger interval following the atrial pace event, during which time the pacemaker will detect V-sense events, while leaving the A2V VSP interval unchanged, at the end of which any required VSP will be generated. In yet another method, the interval from A-pace to V-pace, the PAV interval, is shortened, while leaving the overall V2V cycle interval unchanged. This increases the ventricular to artial V2A interval, increasing the detection window for arthythmias. The PAV interval can be shortened in response to a recent history of VSP events.

Abstract: Devices, systems and methods are disclosed by which the blood pressure, nervous system activity, and neurohormonal activity may be selectively and controllably reduced by activating baroreceptors. A baroreceptor activation device is positioned near a baroreceptor, preferably a baroreceptor located in the carotid sinus. A control system may be used to modulate the baroreceptor activation device. The control system may utilize an algorithm defining a stimulus regimen which promotes long term efficacy and reduces power requirements/consumption. The baroreceptor activation device may utilize RF-coupled or other electrodes to activate the baroreceptors. The electrodes may be adapted for connection to the carotid arteries at or near the carotid sinus, and may be designed to minimize extraneous tissue stimulation.

Abstract: Devices, systems and methods are described by which the blood pressure, nervous system activity, and neurohormonal activity may be selectively and controllably reduced by activating baroreceptors. A baroreceptor activation device is positioned near a baroreceptor, preferably a baroreceptor located in the carotid sinus. A control system may be used to modulate the baroreceptor activation device. The control system may utilize an algorithm defining a stimulus regimen which promotes long term efficacy and reduces power requirements/consumption. The baroreceptor activation device may utilize electrodes to activate the baroreceptors. The electrodes may be adapted for connection to the carotid arteries at or near the carotid sinus, and may be designed to minimize extraneous tissue stimulation.

Abstract: Methods for improving detection of arrhythmias by adaptively increasing arrhythmia detection intervals. One method includes increasing the V2V, the overall cardiac cycle length, thereby decreasing the pacing rate in the presence of ventricular safety paces (VSPs). Another method includes shortening the trigger interval following the atrial pace event, during which time the pacemaker will detect V-sense events, while leaving the A2V VSP interval unchanged, at the end of which any required VSP will be generated. In yet another method, the interval from A-pace to V-pace, the PAV interval, is shortened, while leaving the overall V2V cycle interval unchanged. This increases the ventricular to artial V2A interval, increasing the detection window for arthythmias. The PAV interval can be shortened in response to a recent history of VSP events.

Abstract: A battery powered cardioverter or defibrillator employing a DC-DC converter for charging high voltage output capacitors and for delivering biphasic cardioversion or defibrillation pulses through a bridge circuit including high and low side drive circuits under the control of a microprocessor controlled arrhythmia detection system. Upon the detection of an arrhythmia and the selection of cardioversion/defibrillation therapy, the charging of the high voltage output capacitors is commenced and the capacitor voltage enables a regulated voltage source for the high and low side drive circuits for the high power IGTs of each branch of the bridge circuit. High voltage switching transients are suppressed from re-triggering or otherwise affecting operation of the drive circuits. Fail safe circuitry disables operation of the drive circuits in the event that the first and second control signals are inadvertently provided simultaneously or overlap.

Abstract: An automatic implantable device for detecting and differentiating between tachyarrhythmias in order to therapeutically stimulate the heart in response thereto, particularly for distinguishing fibrillation from tachycardia and to provide appropriate therapies for each condition. The event intervals between successive heart depolarizations are measured, stored and classified as within fibrillation or tachycardia interval ranges. The numbers of intervals falling within the fibrillation and tachycardia interval ranges are employed to distinguish fibrillation from tachycardia. The number of intervals required to detect and discriminate between tachycardia and fibrillation in situations where the tachyarrhythmia includes intervals in both interval ranges is reduced by adjusting the interval ranges as a function of the relative distribution of measured intervals within the interval ranges.

Abstract: An automatic implantable device for detecting and differentiating between tachyarrhythmias in order to therapeutically stimulate the heart in response thereto, particularly for distinguishing fibrillation from tachycardia and to provide appropriate therapies for each condition. The event intervals between successive heart depolarizations are measured, stored and classified as within fibrillation or tachycardia interval ranges. The numbers of intervals falling within the fibrillation and tachycardia interval ranges are employed to distinguish fibrillation from tachycardia. The number of intervals required to detect and discriminate between tachycardia and fibrillation in situations where the tachyarrhythmia includes intervals in both interval ranges is reduced by adjusting the interval ranges as a function of the relative distribution of measured intervals within the interval ranges.

Abstract: An implantable defibrillator provided with a plurality of defibrillation electrodes, which may be reconfigured to define a plurality of defibrillation pathways. The device is capable of measuring the impedance along a selected defibrillation pathway, during delivery of an impedance pulse, and monitoring the success or failure of the pulse to accomplish defibrillation or cardioversion. In response to a detected failure to accomplish cardioversion in conjunction with a measured change of impedance of greater than a predetermined amount, a new defibrillation pathway is selected, which may employ some or all of the electrodes employed to define the original impedance pathway. The device also includes apparatus for varying the relative amplitude of defibrillation pulses applied to individual electrodes used in sequential or simultaneous, multiple electrode pulse regimens, in order to equalize current distribution, in response to measured pathway impedances.

Abstract: An implantable defibrillator provided with a plurality of defibrillation electrodes, which may be reconfigured to define a plurality of defibrillation pathways. The device is capable of measuring the impedance along a selected defibrillation pathway, during delivery of an impedance pulse, and monitoring the success or failure of the pulse to accomplish defibrillation or cardioversion. In response to a detected failure to accomplish cardioversion in conjunction with a measured change of impedance of greater than a predetermined amount, a new defibrillation pathway is selected, which may employ some or all of the electrodes employed to define the original impedance pathway. The device also includes apparatus for varying the relative amplitude of defibrillation pulses applied to individual electrodes used in sequential or simultaneous, multiple electrode pulse regimens, in order to equalize current distribution, in response to measured pathway impedances.

Abstract: A programmable cardiac pacemaker pulse generator utilizing digital circuitry for controlling the provision of cardiac stimulating pulses. The pulse generator is capable of having the rate, the pulse width, the pulse amplitude, the refractory period, the sensitivity and the mode of operation programmed. In addition, the pulse generator can have the output inhibited and can respond to programming signals causing a threshold margin test to be performed, effects of closure of the reed switch overridden, a hysteresis function added and a high rate exceeding the normal upper rate limit programmed. Many of the programmable functions of the pulse generator can either be programmed on a permanent or a temporary basis. The pulse generator further includes means for signaling the acceptance of a programming signal, and means to reset the program acceptance circuit if extraneous signals are detected as programming signals.

Abstract: Memory control circuitry for use in a pacemaker or other medical device for setting volatile memory to a known configuration if the battery voltage and/or current drops below the level required for reliable operation of the memory devices.

Abstract: A programmable cardiac pacemaker pulse generator utilizing digital circuitry for controlling the provision of cardiac stimulating pulses. The pulse generator is capable of having the rate, the pulse width, the pulse amplitude, the refractory period, the sensitivity and the mode of operation programmed. In addition, the pulse generator can have the output inhibited and can respond to programming signals causing a threshold margin test to be performed, effects of closure of the reed switch overridden, a hysteresis function added and a high rate exceeding the normal upper rate limit programmed. Many of the programmable functions of the pulse generator can either be programmed on a permanent or a temporary basis. The pulse generator further includes means for signaling the acceptance of a programming signal, and means to reset the program acceptance circuit if extraneous signals are detected as programming signals.

Abstract: A programmable cardiac pacemaker pulse generator utilizing digital circuitry for controlling the provision of cardiac stimulating pulses. The pulse generator is capable of having the rate, the pulse width, the pulse amplitude, the refractory period, the sensitivity and the mode of operation programmed. In addition, the pulse generator can have the output inhibited and can respond to programming signals causing a threshold margin test to be performed, effects of closure of the reed switch overridden, a hysteresis function added and a high rate exceeding the normal upper rate limit programmed. Many of the programmable functions of the pulse generator can either be programmed on a permanent or a temporary basis. The pulse generator further includes means for signaling the acceptance of a programming signal, and means to reset the program acceptance circuit if extraneous signals are detected as programming signals.

Abstract: A programmable cardiac pacemaker pulse generator utilizing digital circuitry for controlling the provision of cardiac stimulating pulses. The pulse generator is capable of having the rate, the pulse width, the pulse amplitude, the refractory period, the sensitivity and the mode of operation programmed. In addition, the pulse generator can have the output inhibited and can respond to programming signals causing a threshold margin test to be performed, effects of closure of the reed switch overridden, a hysteresis function added and a high rate exceeding the normal upper rate limit programmed. Many of the programmable functions of the pulse generator can either be programmed on a permanent or a temporary basis. The pulse generator further includes means for signalling the acceptance of a programming signal, and means to reset the program acceptance circuit if extraneous signals are detected as programming signals.

Abstract: A programmable cardiac pacemaker pulse generator utilizing digital circuitry for controlling the provision of cardiac stimulating pulses. The pulse generator is capable of having the rate, the pulse width, the pulse amplitude, the refractory period, the sensitivity and the mode of operation programmed. In addition, the pulse generator can have the output inhibited and can respond to programming signals causing a threshold margin test to be performed, effects of closure of the reed switch overridden, a hysteresis function added and a high rate exceeding the normal upper rate limit programmed. Many of the programmable functions of the pulse generator can either be programmed on a permanent or a temporary basis. The pulse generator further includes means for signaling the acceptance of a programming signal, and means to reset the program acceptance circuit if extraneous signals are detected as programming signals.

Abstract: A programmable cardiac pacemaker pulse generator utilizing digital circuitry for controlling the provision of cardiac stimulating pulses. The pulse generator is capable of having the rate, the pulse width, the pulse amplitude, the refractory period, the sensitivity and the mode of operation programmed. In addition, the pulse generator can have the output inhibited and can respond to programming signals causing a threshold margin test to be performed, effects of closure of the reed switch overriden, a hysteresis function added and a high rate exceeding the normal upper rate limit programmed. Many of the programmable functions of the pulse generator can either be programmed on a permanent or a temporary basis. The pulse generator further includes means for signaling the acceptance of a programming signal, and means to reset the program acceptance circuit if extraneous signals are detected as programming signals.

Abstract: A programmable cardiac pacemaker pulse generator utilizing digital circuitry for controlling the provision of cardiac stimulating pulses. The pulse generator is capable of having the rate, the pulse width, the pulse amplitude, the refractory period, the sensitivity and the mode of operation programmed. In addition, the pulse generator can have the output inhibited and can respond to programming signals causing a threshold margin test to be performed, effects of closure of the reed switch overridden, a hysteresis function added and a high rate exceeding the normal upper rate limit programmed. Many of the programmable functions of the pulse generator can either be programmed on a permanent or a temporary basis. The pulse generator further includes means for signaling the acceptance of a programming signal, and means to reset the program acceptance circuit if extraneous signals are detected as programming signals.