Abstract: The present invention provides structures and methods for delivering a complex slow-rise defibrillation waveform wherein in lieu of the simple truncation of prior art defibrillation waveforms, when a predetermined amplitude is reached for an ascending waveform (e.g., a ramp waveform), the waveform transitions to an exponential decay portion for a period of time and at the expiration of the period of time, a truncation occurs. In the event that a first complex bi-phasic ramp wave form is implemented, a second opposite polarity waveform may be delivered. Said second waveform is preferably of similar shape to the first waveform, but of a less magnitude amplitude, although the second waveform may comprise a traditional waveform. The implementation and feasibility of the waveforms according to the present invention in an ICD or an AED is relatively simple while providing significant advantages not previously known or used in the prior art.

Abstract: An apparatus for discriminating between cardiac events that includes an input circuit receiving signals indicative of the cardiac events, a first output circuit generating pulses in response to the received signals, and a microprocessor determining whether a signal received by the input circuit subsequent to the generated pacing pulses corresponds to a predetermined cardiac event in response to an elapsed time period between the generated pulses and the subsequently received signal and a predetermined discrimination threshold.

Abstract: Apparatus and an associated method are provided for detecting a cardiac arrhythmia and delivering cardioversion therapy after first delivering a prepulse inhibition stimulus directly to the central nervous system for inhibiting cardioversion pain perceived by the patient. Circuitry for controlling and delivering a prepulse stimulus may be included in the cardioverting device or in a separate stimulating device that is in communication with the cardioverting device. The prepulse stimulus is delivered directly to the spinal cord via a spinal cord lead at a predetermined time interval prior to cardioversion shock delivery.

Abstract: A system and method for delivering both anti-tachy pacing (ATP) therapy and high-voltage shock therapy in response to detection of abnormal cardiac rhythms is disclosed. The system controls the time between delivering ATP therapy and the charging of high-voltage capacitors in preparation for shock delivery based on a predetermined set of criteria. In one embodiment, the inventive system operates in an ATP During Capacitor Charging (ATP-DCC) mode wherein all, or substantially all, of the ATP therapy is delivered during charging of the high-voltage capacitors. Based on evaluation of the predetermined set of criteria, the system may switch to an additional ATP Before Capacitor Charging (ATP-BCC) mode, wherein substantially all of the ATP therapy is delivered prior to charging of the high-voltage capacitor. According to one aspect of the invention, the predetermined set of criteria is based, at least in part, on the effectiveness of previously-delivered ATP therapy.

Abstract: The present invention provides a system and method for treating an arrhythmia of the heart. The system and method involves delivery of anti-tachy pacing (ATP) pulses to the heart, possibly followed by the delivery of a high-voltage shock. ATP delivery is controlled such that the time of delivery of any high-voltage shock is not affected by the prior delivery of the ATP pulses. System control may be accomplished using one or more programmable parameters, which may include a user-specified shock energy.

Abstract: A device and method to detect slow ventricular tachycardia, deliver anti-tachycardia pacing therapies, and delay a scheduled shock therapy if the ventricular tachycardia is not terminated or accelerated. Preferably, a shock therapy is delayed after verifying hemodynamic stability based on a hemodynamic sensor. After a shock is delayed, the device operates in a high alert mode for redetecting an accelerated tachycardia. Anti-tachycardia pacing therapies are repeated during the shock delay. A number of conditions can trigger delivery of the delayed shock therapy including a specified period of elapsed time; determination that the patient is likely to be asleep; detection of myocardial ischemia; detection of compromised hemodynamics, or detection of a substantially prone position or sudden change in position.

Abstract: The invention provides systems to prevent the delivery of anti-tachycardia pacing (ATP) following a defibrillation threshold (DFT) induction at implant. An algorithm that classifies episodes as induced or spontaneous is implemented, thereby enabling the ATP during charging feature to be operable only when spontaneous episodes are detected while temporarily suspending the ATP feature during the delivery of defibrillation shock after induction has been confirmed. Further, a user interface enables users to interact with an implantable medical device (IMD), particularly for setting a defibrillation threshold (DFT) or a 50 Hz burst from a single programmer screen. The user interface includes various functionalities to promote quick user access to parameters that govern diagnosis, therapy and other features of the IMD. A single screen enables the user to complete automatic and/or manual DFT inductions or a 50 Hz burst from a programmer interface while acquiring associated documentation from the same interface.

Abstract: The present invention outlines structures and methods for delivering a controllable amount of energy to a patient by automatically compensating for the load impedance detected by an implantable-cardioverter defibrillator (ICD). The invention employs high speed, switching power converter technology for the efficient generation of high energy, arbitrary waveforms. Unlike a linear amplifier, switching power converters deliver high-energy waveforms with an efficiency that is independent of the size and amplitude of the desired waveform. An ICD that uses a switching power converter to deliver the desired energy to the patient stores the energy to be delivered in a storage capacitor. The converter then transforms this energy into an arbitrarily shaped output voltage-controlled or current-controlled waveform by switching the storage capacitor in and out of the output circuit at a high rate of speed. Preferably, the waveform comprises a ramp-type waveform.

Abstract: A system and method for delivering both anti-tachy pacing (ATP) therapy and high-voltage shock therapy in response to detection of abnormal cardiac rhythms is disclosed. The system controls the time between delivering ATP therapy and the charging of high-voltage capacitors in preparation for shock delivery based on a predetermined set of criteria. In one embodiment, the inventive system operates in an ATP During Capacitor Charging (ATP-DCC) mode wherein all, or substantially all, of the ATP therapy is delivered during charging of the high-voltage capacitors. Based on evaluation of the predetermined set of criteria, the system may switch to an additional ATP Before Capacitor Charging (ATP-BCC) mode, wherein substantially all of the ATP therapy is delivered prior to charging of the high-voltage capacitor. According to one aspect of the invention, the predetermined set of criteria is based, at least in part, on the effectiveness of previously-delivered ATP therapy.

Abstract: An implantable anti-tachycardia pacemaker having the capability of switching from a first pacing regimen to a second pacing regimen, without waiting to determine whether the first pacing regimen actually is successful in terminating the tachycardia. The device first delivers a short series of pacing pulses at the defined parameters of the first pacing regimen and then interrupts delivery of pacing pulses and measures the return cycle of the subsequent spontaneous depolarization. The device then resumes delivery of the first pacing regimen for a second, greater number of pacing pulses and again measures the return cycle. In the event that no increase in the return cycle occurs following the delivery of the longer series of pacing pulses, the device terminates the pacing regimen presently underway, and initiates the next scheduled therapy. In the event that an increase in the return cycle is detected, the device may simply deliver the programmed number of pacing pulses defined for the first pacing regimen.

Abstract: An implantable anti-arrhythmia device such as a defibrillator or anti-tachycardia pacemaker with an associated patient activator. In response to the patient activation signal, the implanted device notifies the activator whether an atrial rhythm requiring treatment is present and whether a therapy is available for delivery in response to the patient's request. After the patient is notified that a therapy is pending, the implanted device charges its output capacitors and thereafter determines whether opportunities for prompt synchronization are present with a desired frequency, over a preceding series of depolarizations. If both conditions are met, the likelihood that a defibrillation or cardioversion pulse can be delivered quickly following a patient initiated retrigger signal is high, and the device notifies the patient's activator that it will await receipt of a patient retrigger signal, as a prerequisite for a delivery of the cardioversion or defibrillation pulse.

Abstract: In an implantable pacemaker/cardioverter/defibrillator, a system for correlating the delivery of a cardioversion therapy to an optimum point or phase of the respiratory cycle of the patient to effect delivery of the therapy when the impedance between the cardioversion electrodes is minimized. In a first application for use with cardioversion electrodes located substantially in contact with the heart chamber, the optimum point or phase is at the end of inspiration. In a second application for use with at least one cardioversion electrode located remotely from the heart chamber, the optimum point or phase is at end expiration or beginning of inspiration. The cardioversion therapy is delivered in synchrony with a ventricular sense event, if present. If the optimum point or phase of the respiratory cycle cannot be determined during a therapy time, a pre-shock may be delivered to elicit a respiration cycle through a stimulated contraction of the diaphragm.

Abstract: An implantable anti-arrhythmia device such as a defibrillator or anti-tachycardia pacemaker with an associated patient activator. In response to the patient activation signal, the implanted device notifies the activator whether an atrial rhythm requiring treatment is present and whether a therapy is available for delivery in response to the patient's request. After the patient is notified that a therapy is pending, the implanted device charges its output capacitors and thereafter determines whether opportunities for prompt synchronization are present with a desired frequency, over a preceding series of depolarizations. If both conditions are met, the likelihood that a defibrillation or cardioversion pulse can be delivered quickly following a patient initiated retrigger signal is high, and the device notifies the patient's activator that it will await receipt of a patient retrigger signal, as a prerequisite for a delivery of the cardioversion or defibrillation pulse.

Abstract: A method and apparatus for inducing fibrillation in a patient, for example to verify the efficacy of a defibrillator system. In the disclosed embodiment, an implantable cardioverter-defibrillator has an output stage coupled via a plurality of leads to the patient's heart. When it is desired to induce fibrillation in the patient, the device's control circuitry initiates an output capacitor charging cycle and subsequent delivery of a multi-phase fibrillation inducing stimulus to the heart. The multiple phases of the stimulus reflect an incremental discharging of the output capacitor. In one embodiment, the stimulus has three phases, with the first two separated by a time interval equal to or slightly less than the patient's "vulnerability window," which is defined as the time period following a paced cardiac event during which repolarization of the cardiac muscle is occurring, rendering the heart susceptible to induced fibrillation.

Abstract: A method and apparatus for treating atrial tachyarrhythmias, particularly atrial fibrillation. High energy pulses are delivered between electrodes located in the right atrium/SVC, the right ventricle and the coronary sinus/great vein, with the right ventricular and coronary sinus/great vein electrodes connected in common. Optionally a subcutaneous electrode, preferably located in the left pectoral area may also be employed, coupled in common to the right atrial/SVC electrode.

Abstract: A method for determining the far field radar signature of relatively large and complex objects, like a fighter aircraft, and the facility to provide the data for the method. The method includes reflecting different frequencies of near field radar energy off of an object while translating the object in a radial direction with respect to the radar so the resulting radar return includes a moving signal representative of the radar return of the object and a stationary return representative of environmental clutter. The environmental clutter and R 4 amplitude variations caused by signal strength variations due to the different overall reflection distances during translation are removed from the radar signal. Multipath reflections may also be removed.