Abstract: An apparatus and method for delivering electrical shock therapy in order to treat atrial tachyarrhythmias such as fibrillation utilizes a dynamically varying threshold to detect R-waves and synchronously deliver a defibrillation shock.

Abstract: An apparatus and method for delivering electrical shock therapy in order to treat atrial tachyarrhythmias such as fibrillation utilizes a dynamically varying threshold to detect R-waves and synchronously deliver a defibrillation shock.

Abstract: An improved protection mechanism to protect from unintended execution of critical tasks operates, in one example embodiment, by receiving a request to start a task by a first process. The first process informs a second process of running an algorithm to verify the legitimacy of the received request to determine the need to start the task. The second process stores the information regarding the starting the algorithm by the first process. The first process runs the algorithm to verify the legitimacy of the received request, and conveys an outcome of the verification to the second process. The second process enables the start of the task by the first process based on the outcome of the verification and a checking of the stored information and the first process starts the task.

Abstract: An atrial cardioverter for cardioverting atria of a heart while sustaining atrial pacing of the heart. The cardioverter includes a pacer for pacing the heart in one of a plurality of modes including an atrial pacing, atrial inhibited mode, and an atrial pacing, ventricular inhibited mode, an atrial tachyarrhythmia detector for detecting an atrial tachyarrhythmia of the heart, and a mode control for changing the mode of the pacer from the atrial pacing, atrial inhibited mode to the atrial pacing, ventricular inhibited mode responsive to the atrial tachyarrhythmia detector detecting an atrial tachyarrhythmia of the heart. A cardioverter stage applies cardioverting energy to the atria responsive to the atrial tachyarrhythmia detector detecting an atrial tachyarrhythmia and after the pacer mode change.

Abstract: A continuous monitoring system monitors atrial activity of a heart and activates an atrial fibrillation detector when atrial fibrillation is suspected. The system includes an A wave detector for detecting A waves of the heart and providing an A wave detection signal indicating each detected A wave. The A wave detector has a first threshold and a selectable second threshold higher than the first threshold. An R wave detector for detecting R waves of the heart is coupled to the A wave detector for selecting the second threshold of the A wave detector during each detected R wave of the heart. An atrial cycle length determining stage determines atrial cycle lengths from the A wave detection signal and a comparator activates atrial fibrillation detection when an atrial cycle length is shorter than a predetermined cycle length.

Abstract: There is disclosed an implantable atrial defibrillator for applying cardioverting electrical energy to the atria of a heart when the atria are in need of cardioversion. The atrial defibrillator includes a sense channel adapted to be associated with at least one atrium of the heart to provide a cardiac signal during a plurality of cardiac cycles of the heart and a timer which determines a cardiac interval duration for each of the cardiac cycles. The defibrillator further includes an atrial detector for analyzing the cardiac signal provided by the sense channel during selected ones of the cardiac cycles wherein each one of the selected ones of the cardiac cycles has a cardiac interval greater than a predetermined duration.A cardioverter applies cardioverting electrical energy to the atria responsive to the atrial detector detecting atrial fibrillation of the heart.

Abstract: An atrial defibrillation system includes an implantable atrial defibrillator including an atrial fibrillation detector and an atrial cardiovertor, and an external communication device dimensioned to be hand-held and including an RF transmitter for transmitting a command signal to the implanted defibrillator. The implantable defibrillator includes a receiver for receiving the command signal, activation means responsive to receipt of the command signal for activating the atrial fibrillation detector and the atrial cardiovertor if the atrial fibrillation detector detects atrial fibrillation, and an RF transmitter for transmitting an acknowledgment signal to the external communication device responsive to the receiver receiving the command signal. The external communication device further includes a receiver for receiving the acknowledgment signal and an indicator for providing a perceptible indication responsive to receipt of the acknowledgment signal.

Abstract: A defibrillator system includes an implantable defibrillator and a non-implantable external receiver. The implantable defibrillator includes a first sense channel for generating a first electrogram and a second sense channel for generating a second electrogram. The defibrillator further includes a cardioverter for applying cardioverting electrical energy to the heart and a transmitter for transmitting the first and second electrograms. The non-implantable receiver includes a display for simultaneously displaying the first and second electrograms. The implantable defibrillator may further include an event detector having a threshold for detecting cardiac events in one of the electrograms and an event marker generator for generating an event marker for each detected cardiac event. The transmitter transmits the event detection markers and the display displays the event detection markers and the thresholds with the corresponding electrogram.

Abstract: An atrial defibrillator applies cardioverting electrical energy to the atria of a human heart in need of cardioversion. The defibrillator includes an electrode pair and a sense amplifier associated with the atria of the heart for sensing electrical activity of the heart during a plurality of cardiac cycles to provide a cardiac signal. A detector is responsive to the cardiac signal for detecting cardiac events. During each cardiac cycle of the plurality of cardiac cycles, a time for counting is established wherein each time for counting has a total duration less than the duration of its corresponding cardiac cycle. A counter counts the cardiac events detected by the detector during the time for counting of the plurality of cardiac cycles to provide a cardiac event count. A comparator compares the cardiac event count to a predetermined cardiac event count.

Abstract: An implantable automatic atrial defibrillator powered by a depletable battery power source conserves battery power for extending the predicted life of the defibrillator by intermittently detecting for atrial fibrillation. The atrial defibrillator includes a real time clock which, at spaced apart predetermined times, causes heart activity data to be stored in a memory. Thereafter, a normally deactivated atrial fibrillation detector is activated for processing the stored data to detect for atrial fibrillation.

Abstract: An apparatus reliably detects a depolarization activation wave of the heart. The apparatus includes a sensor in electrical contact with the heart for sensing electrical activity of the heart and including an amplifier for amplifying the sensed electrical activity according to a variable gain and providing a signal corresponding to the depolarization activation wave. The apparatus further includes an output circuit coupled to the sensor for producing an electrical output corresponding to the depolarization activation wave sensed by the sensor when the signal exceeds a threshold. The apparatus still further includes a control circuit coupled to the sensor and the output circuit for varying at least one of the gain and the threshold to maintain a predetermined sense margin between the sensed electrical activity and the gain and the threshold.

Abstract: A telemetry system and method of monitoring cardiac activity or providing therapy to the heart for an implantable cardiac device. The system includes a receiver and a transmitter in an external programmer and a receiver section and transmitter section in the cardiac device. The receiver section and the transmitter section of the cardiac device generally remain in a de-energized state. The receiver section is energized at spaced apart time intervals to detect an initiation signal transmitted by the external programmer. If the initiation signal is detected, the receiver section and the transmitter section of the cardiac device are fully activated. The external programmer includes a signal strength indicating means for providing an indication of received signal strength which the user can use to position the receiver and transmitter in the external programmer for optimum received signal strength. An antenna is disposed in the header of the implanted device to facilitate communication at high speed.

Abstract: A pulse generator for use in a defibrillator provides cardioverting electrical energy to a heart through at least one lead having a pair of electrodes associated with the heart. Electrical energy is applied to the heart with a biphasic waveform having a first cardioverting phase and a second cardioverting phase. A crosspoint switch selectively couples a storage capacitor to the lead means. A master switch decouples the crosspoint switch from the storage capacitor while the crosspoint switch connections are changed between the first cardioverting phase and the second cardioverting phase. A control circuit provides independent control of the duration of both the first and second cardioverting phases.

Abstract: A pulse generator for use in implantable atrial defibrillator provides cardiovertinq electrical energy to the atria of a heart through at least one lead having a pair of electrodes associated with the atria of the heart. The pulse generator includes a depletable, low voltage, power source such as a battery. A charging circuit coupled to the battery includes a flyback transformer for converting the battery voltage to low duty cycle pulsating high voltage electrical energy to store the high voltage electrical energy in a storage capacitor coupled to the charging circuit. A crosspoint switch selectively couples the storage capacitor to the electrodes for applying a portion of the stored electrical energy to the atria of the heart for cardioverting the atria of the heart.

Abstract: An implantable atrial defibrillator provides cardioverting electrical energy to the atria of a human heart in need of cardioversion. The atrial defibrillator includes a first detector for detecting ventricular activations of the heart, a second detector for detecting atrial activity of the heart, and an atrial fibrillation detector responsive to the second detector for determining when the atria of the heart are in need of cardioversion. The atrial defibrillator also includes a cardioverting stage for applying the cardioverting electrical energy to the atria of the heart when the atria of the heart are in need of cardioversion and when the time between immediately successive ventricular activations is greater than a preselected minimum time interval.

Abstract: A physiological instrument that includes a first component comprising an ECG monitor and a second component comprising a defibrillator. The second component may also include a pacemaker mounted to and electrically connected with the defibrillator. The first and second components may communicate with one another entirely by means of three optical communication channels, each channel including an optical signal path that includes windows through which the optical signals pass into and out of the components. The components may therefore operate in a fully integrated manner despite the fact that no electrical signal path exists between the components.