Abstract: An implantable cardiac device detects a patient therapy request originating from external to the implantable device. A shock therapy delay period is timed in response to the detection of the patient therapy request. Atrial shock therapy is provided to the patient after expiration of the shock therapy delay period (if the presence of an ongoing atrial arrhythmia is detected). The patient therapy request may be provided by a patient activator including a magnet for operating a reed switch in the implanted device to provide the request. A patient activator including an input and receiver/transmitter circuitry may be employed to request the immediate providing of atrial shock therapy, and/or to set the duration the shock therapy delay period. By allowing specific delays to therapy after a therapy request, a patient can prepare for the requested therapy and thereby mitigate therapy discomfort.

Abstract: An implanted cardiac device detects an atrial arrhythmia and provides periodically updated atrial arrhythmia status as long as the arrhythmia is ongoing. A patient may request an indication of ongoing atrial arrhythmia status from external to the patient using a patient activator. The patient activator may include a magnet for closing a reed switch in the implanted device to provide the request or may provide the request over a telemetry link to the implanted device. The implanted device may provide the requested atrial arrhythmia status and other information in the form of an audible tone produced by the implanted device or as a message telemetered from the implanted device to the patient activator. The patient activator may include a tone detector and display for providing a visual indication of the atrial arrhythmia status indication. The magnet activator may also be employed to request or withhold atrial shock therapy.

Abstract: An implantable cardiac device detects a patient therapy request originating from external to the implantable device. A shock therapy delay period is timed in response to the detection of the patient therapy request. Atrial shock therapy is provided to the patient after expiration of the shock therapy delay period (if the presence of an ongoing atrial arrhythmia is detected). The patient therapy request may be provided by a patient activator including a magnet for operating a reed switch in the implanted device to provide the request. A patient activator including an input and receiver/transmitter circuitry may be employed to request the immediate providing of atrial shock therapy, and/or to set the duration the shock therapy delay period. By allowing specific delays to therapy after a therapy request, a patient can prepare for the requested therapy and thereby mitigate therapy discomfort.

Abstract: Cardioprotective pre-excitation pacing may be applied to stress or de-stress a particular myocardial region delivering of pacing pulses in a manner that causes a dyssynchronous contraction. Such dyssynchronous contractions are responsible for the desired cardioprotective effects of pre-excitation pacing. A method and device for applying reverse hysteresis and mode switching to the delivery of such cardioprotective pacing are described.

Abstract: An implanted cardiac device detects an atrial arrhythmia and provides periodically updated atrial arrhythmia status as long as the arrhythmia is ongoing. A patient may request an indication of ongoing atrial arrhythmia status from external to the patient using a patient activator. The patient activator may include a magnet for closing a reed switch in the implanted device to provide the request or may provide the request over a telemetry link to the implanted device. The implanted device may provide the requested atrial arrhythmia status and other information in the form of an audible tone produced by the implanted device or as a message telemetered from the implanted device to the patient activator. The patient activator may include a tone detector and display for providing a visual indication of the atrial arrhythmia status indication. The magnet activator may also be employed to request or withhold atrial shock therapy.

Abstract: A depolarization sensing threshold can be determined using an amplitude-limited portion of a cardiac signal received using an implantable medical device. One or more cardiac depolarizations can be detected using the cardiac signal and the depolarization sensing threshold.

Abstract: An atrial event and a ventricular event can be received, and an atrioventricular (AV) delay can be provided using information about the atrial and ventricular events. The AV delay can be increased after a first condition is satisfied to allow a heart to regain intrinsic control of ventricular activation, and changed after a second condition is satisfied to allow the heart to remain in intrinsic control of ventricular activation.

Abstract: A system and method for providing pacing pulses after a cardioversion/defibrillation shock, where the pacing pulses have a pacing rate at an initial value. The pacing rate is decreased from the initial value until at least one intrinsic cardiac contraction is detected. In one embodiment, the pacing rate is decreased by a set amount after pacing a set number of cardiac cycles. Providing the set number of pacing pulses and decreasing the pacing rate by the set amount is then repeated until at least one intrinsic cardiac contraction is detected. An intrinsic cardiac rate is then determined from the at least one intrinsic cardiac contraction. The pacing rate is then increased and maintained to be above (i.e., greater than) the intrinsic cardiac rate.

Abstract: A device comprises a cardiac contraction sensing circuit, a timer circuit, an electrical stimulation circuit, and a controller. The timer circuit provides a time duration of an atrial-atrial interval between successive atrial contractions, a ventricular-ventricular interval between successive ventricular contractions, and an atrial-ventricular (A-V) interval between an atrial contraction and a same cardiac cycle ventricular contraction. The controller includes an event detection module and a pacing module. The event detection module is configured for determining whether A-V block events are sustained over multiple cardiac cycles. The pacing module is configured for providing pacing therapy according to a primary pacing mode that includes AAI(R) mode with independent VVI backup mode, and for switching the pacing therapy to a secondary pacing mode if A-V block events are sustained over multiple cardiac cycles. Other devices and methods are described.

Abstract: A system and method for providing pacing pulses after a cardioversion/defibrillation shock, where the pacing pulses have a pacing rate at an initial value. The pacing rate is decreased from the initial value until at least one intrinsic cardiac contraction is detected. In one embodiment, the pacing rate is decreased by a set amount after pacing a set number of cardiac cycles. Providing the set number of pacing pulses and decreasing the pacing rate by the set amount is then repeated until at least one intrinsic cardiac contraction is detected. An intrinsic cardiac rate is then determined from the at least one intrinsic cardiac contraction. The pacing rate is then increased and maintained to be above (i.e., greater than) the intrinsic cardiac rate.

Abstract: An apparatus and method is presented for treating patients with sinus node dysfunction who have apparently normal intrinsic AV conduction and thus do not require ventricular pacing unless there is an unexpected AV conduction failure. In one embodiment, a cardiac device with dual-chamber pacing capability is programmed to operate in a primary DDI (or DDI(R)) mode adjusted to pace only the atria if intrinsic AV conduction is intact and switch to a secondary DDD (or DDD(R)) mode upon detection of AV block.

Abstract: A cardiac rhythm management system synchronizes the delivery of an atrial defibrillation shock to a ventricular depolarization concluding a present RR interval since the occurrence of the last ventricular depolarization. The present RR interval is deemed “shockable” if, among other things, its ventricular refractory period (VRP), which may be extended by ventricular “noise” occurring during the VRP, is less than a predetermined value, which may be different depending on whether the VRP is initiated by a paced or sensed ventricular depolarization. Alternatively, the present RR interval is deemed shockable if a post-VRP time period before the ventricular depolarization concluding the present RR interval exceeds a predetermined value. In conjunction with one or both of these conditions, other requirements for deeming a present RR interval shockable include comparing the present RR interval duration to a predetermined value, or to a preceding RR or QT interval.

Abstract: A cardiac rhythm management system includes atrial shock timing optimization. Because an atrial tachyarrhythmia, such as atrial fibrillation typically causes significant variability in the ventricular heart rate, resulting in potentially proarrhythmic conditions. The system avoids delivering atrial cardioversion/defibrillation therapy during potentially proarrhythmic conditions because doing so could result in dangerous ventricular arrhythmias. Using Ventricular Rate Regularization (“VRR”) techniques, the system actively stabilizes the ventricular heart rate to obtain less potentially proarrhythmic conditions for delivering the atrial tachyarrhythmia therapy. The intrinsic ventricular heart rate is stabilized at a variable VRR-indicated rate, computed using an infinite impulse response (IIR) filter, and based on the underlying intrinsic ventricular heart rate.

Abstract: An apparatus and method of automatically measuring the lead impedance of a high energy shock lead before delivery of high energy therapy used to treat heart arrhythmia. In one example, an impedance measurement circuit measures the impedance between electrodes in a plurality of pairs of electrodes. The measured lead electrode impedance is compared to a predetermined value to detect if the lead is shorted to another lead. If a high-energy shock electrode is shorted to another lead, a shorted lead indicator is set to a fault state. Based on the state of the shorted lead indicator, a processor prevents or allows the delivery of high energy therapy. By checking for a lead short before delivery of the therapy, all of the energy of the therapy is delivered to the patient rather than being bypassed by a shorted lead connection.

Abstract: An implantable cardiac device detects a patient therapy request originating from external to the implantable device. A shock therapy delay period is timed in response to the detection of the patient therapy request. Atrial shock therapy is provided to the patient after expiration of the shock therapy delay period (if the presence of an ongoing atrial arrhythmia is detected). The patient therapy request may be provided by a patient activator including a magnet for operating a reed switch in the implanted device to provide the request. A patient activator including an input and receiver/transmitter circuitry may be employed to request the immediate providing of atrial shock therapy, and/or to set the duration the shock therapy delay period. By allowing specific delays to therapy after a therapy request, a patient can prepare for the requested therapy and thereby mitigate therapy discomfort.

Abstract: An implanted cardiac device detects an atrial arrhythmia and provides periodically updated atrial arrhythmia status as long as the arrhythmia is ongoing. A patient may request an indication of ongoing atrial arrhythmia status from external to the patient using a patient activator. The patient activator may include a magnet for closing a reed switch in the implanted device to provide the request or may provide the request over a telemetry link to the implanted device. The implanted device may provide the requested atrial arrhythmia status and other information in the form of an audible tone produced by the implanted device or as a message telemetered from the implanted device to the patient activator. The patient activator may include a tone detector and display for providing a visual indication of the atrial arrhythmia status indication. The magnet activator may also be employed to request or withhold atrial shock therapy.

Abstract: A cardiac rhythm management system synchronizes the delivery of an atrial defibrillation shock to a ventricular depolarization concluding a present RR interval since the occurrence of the last ventricular depolarization. The present RR interval is deemed “shockable” if, among other things, its ventricular refractory period (VRP), which may be extended by ventricular “noise” occurring during the VRP, is less than a predetermined value, which may be different depending on whether the VRP is initiated by a paced or sensed ventricular depolarization. Alternatively, the present RR interval is deemed shockable if a post-VRP time period before the ventricular depolarization concluding the present RR interval exceeds a predetermined value. In conjunction with one or both of these conditions, other requirements for deeming a present RR interval shockable include comparing the present RR interval duration to a predetermined value, or to a preceding RR or QT interval.

Abstract: A hybrid cardiac pacemaker in which the operation of the device is controlled by hardware-based controller as supervised by a microprocessor-based controller. The hardware-based controller comprises a plurality of timers that expire when they reach timer limit values stored in registers updatable by the microprocessor, and a combinational logic array for causing the device to generate pace outputs in accordance with timer expirations and sense signals. The combinational logic array may operate the pacemaker in a number of programmed modes in accordance with a mode value stored in a mode control register by the microprocessor.

Abstract: A cardiac rhythm management system synchronizes the delivery of an atrial defibrillation shock to a ventricular depolarization concluding a present RR interval since the occurrence of the last ventricular depolarization. The present RR interval is deemed “shockable” if, among other things, its ventricular refractory period (VRP), which may be extended by ventricular “noise” occurring during the VRP, is less than a predetermined value, which may be different depending on whether the VRP is initiated by a paced or sensed ventricular depolarization. Alternatively, the present RR interval is deemed shockable if a post-VRP time period before the ventricular depolarization concluding the present RR interval exceeds a predetermined value. In conjunction with one or both of these conditions, other requirements for deeming a present RR interval shockable include comparing the present RR interval duration to a predetermined value, or to a preceding RR or QT interval.

Abstract: A system and method for providing pacing pulses after a cardioversion/defibrillation shock, where the pacing pulses have a pacing rate at an initial value. The pacing rate is decreased from the initial value until at least one intrinsic cardiac contraction is detected. In one embodiment, the pacing rate is decreased by a set amount after pacing a set number of cardiac cycles. Providing the set number of pacing pulses and decreasing the pacing rate by the set amount is then repeated until at least one intrinsic cardiac contraction is detected. An intrinsic cardiac rate is then determined from the at least one intrinsic cardiac contraction. The pacing rate is then increased and maintained to be above (i.e., greater than) the intrinsic cardiac rate.