Abstract: A microprocessor-controlled implantable cardiac stimulating device having a normal mode, an intermediate mode, and a backup pacing mode is provided. The device switches from one mode to another in response to the detection of any one of an address error, parity error, opcode error, or watchdog timer error. The microprocessor is shut down during the delivery of a cardioversion or defibrillation shock in order to prevent signals produced by the microprocessor from being subjected to transient electrical signals. The interrupt registers of the microprocessor are also disabled during the delivery of a cardioversion or defibrillation shock. In an alternative embodiment, an implantable cardiac stimulating device is provided with redundant microprocessors in order to detect malfunctions of the microprocessors.
Abstract: An implantable cardioverter defibrillator (ICD) device provides capacitor reformation by successively charging and leaking its output capacitor either a specified number of times or until a specified charge remains on the output capacitor after leakage. The ICD delivers therapy with minimal delay should an arrhythmia detection occur during the capacitor reformation process by anticipating an arrhythmia detection and dumping the reformation energy stored on the output capacitor to an acceptable level as soon as a possible arrhythmia detection is anticipated. The ICD further measures the energy level of the last charge delivered following each delivery so that the energy level of subsequent charges may be adjusted to provide optimal therapy to the patient if prior therapy attempts have not successfully terminated the arrhythmia.
Type:
Grant
Filed:
January 23, 1997
Date of Patent:
August 11, 1998
Assignee:
Pacesetter, Inc.
Inventors:
Timothy J. Starkweather, Kelly H. McClure, Min-Yaug Yang
Abstract: Methods and apparatus for controlling an implantable medical device, such as an implantable cardiac stimulating device, using voice commands are provided. A voice command given by a user is converted into digital data. The digital data are processed in order to recognize the voice command. Once the voice command is recognized, it is telemetered to the implantable device. In a preferred embodiment, the voice command must be confirmed by the user before it is executed.
Abstract: Methods and apparatus for identifying implantable cardiac devices are provided. Cardiac devices are classified as belonging to one of various device families, each of which may use a different communications protocol to communicate with an implantable cardiac device programmer. The family identification times anticipated for establishing a communications channel between the programmer and implantable cardiac devices in various device families are stored by the programmer. In addition, the programmer maintains a record of the implantable cardiac device families with which it has successfully communicated. The programmer identifies implantable cardiac devices based on the family identification time and record information, which reduces the amount of time necessary to complete family identification.
Abstract: An implantable pacemaker accurately senses the regular atrial rhythm even though some portions of the atrial rhythm, e.g., every other P-wave, may potentially be masked or hidden within the ventricular absolute refractory period. Such sensing includes unmasking or uncovering any hidden P-waves, thereby allowing an accurate atrial rate to be determined. The hidden P-waves are uncovered by: changing the PV delay, not tracking a sensed P-wave, or comparing the incoming morphology of the atrial channel signal to a prior stored baseline morphology signal. The accurate atrial rate, once determined, allows the presence of an atrial tachycardia to be reliably confirmed, thereby enabling appropriate atrial anti-tachycardia pacing (ATP) procedures to be invoked, or mode switching from an atrial synchronous mode of operation, e.g., DDD, to a non-atrial synchronous mode, e.g., VVIR.
Type:
Grant
Filed:
July 11, 1995
Date of Patent:
August 4, 1998
Assignee:
Pacesetter, Inc.
Inventors:
Brian M. Mann, Joseph J. Florio, Laurence S. Sloman
Abstract: A blood flow velocity measurement device is devised where there exist such entities within the fluid which are detectable when axially flowing (passing by) an appropriate detector of known and well defined dimensions mounted onto a catheter. The entities produced for instance by a generator, when flowing by the detector, induced a known single response, the response bearing direct correlation to the flow velocity, in the form of direct reciprocity to the velocity and direct proportion to the length of the sensitive length of the detector. Autocorrelation of the function obtained by the overlap and pile-up of successive events is calculated and from the characteristic points in the autocorrelation function the axial velocity is inferred. The measurement is best when the probing beam is perpendicular to the flow.
Abstract: Methods and apparatus are provided for storing intracardiac electrogram (IEGM) and other cardiac data in an implantable cardiac device. When a physician wishes to create a cardiac data record containing the IEGM and other cardiac data, the physician directs the cardiac device to store the data on demand. A number of cardiac data records can be stored. Data records may also be stored after a delay period following a predetermined cardiac event. When the implantable cardiac device detects the predetermined cardiac event, the delay period begins. At the expiration of the delay period, the implantable cardiac device stores a cardiac data record. Cardiac data records can also be stored according to a predetermined schedule.
Abstract: In a method for classifying IEGM waveforms in dependence of the workload of a patient, a predetermined number of IEGM-signals, each signal extending over at least one segment of one heart beat cycle, are registered, whereafter the IEGM-signals are fed to a neural network and an encoded form of the signals is formed using said neural network. This encoded form is stored in a memory, for use in classifying further registered IEGM-signals. In an active cardiac implant connectable to an implantable electrode arrangement adapted for in vivo delivery of stimulation pulses to a heart, IEGM signals present are obtained from one or more of the electrodes. A pulse generator connected to the electrode arrangement, generates and emits stimulation pulses with a variable stimulation interval between successive stimulation pulses.
Abstract: A heart stimulator, with verification of capture in the atrium of a heart, contains an atrial pulse generator which, via an atrial electrode, emits stimulation pulses in the atrium and a ventricular detector which senses depolarization signals in the ventricle via a ventricular electrode. The time which elapses between two consecutive stimulation pulses emitted in the atrium can be varied, and variation in ventricular events associated with the stimulation pulses is studied. If the ventricular events vary in time in the same way stimulation pulses emitted in the atrium vary, AV conduction is functional, and capture is present in the atrium.
Abstract: A ventricular tachycardia (VT) complex is distinguished from a sinus tachycardia or a supraventricular tachycardia. A template based on morphology of a normal sinus rhythm is collected. A test signal is compared against the template to determine how closely the test and template signals correspond based on morphology. The comparison is done based on peak information in the template and the test signal. A score is generated to indicate the degree of similarity between the template and the test signal. The peak information is extracted as follows. First, a group of three consecutive peaks having a largest cumulative peak amplitude is located in the template and in the test signal. The polarity, position and area of each peak within the group is then determined. The area of each peak is normalized. The polarities, positions and normalized areas represent the peak information that is used for comparison.
Type:
Grant
Filed:
December 17, 1996
Date of Patent:
July 14, 1998
Assignee:
Pacesetter, Inc.
Inventors:
Timothy Scott Olson, April Catherine Pixley, Michael O. Williams
Abstract: Methods and apparatus are provided for alleviating the effects of crosstalk in an implantable stimulation device. An autoblanking approach is provided whereby the total blanking interval is made up of an absolute blanking interval followed by a retriggerable relative blanking interval. The implantable stimulation device sensing circuitry is disabled during the absolute blanking interval and enabled during the relative blanking intervals. If a signal is detected during a relative blanking interval, a successive relative blanking interval is initiated. If no signal is detected, then relative blanking terminates. Further, an approach for combining safety standby pacing with autoblanking is provided. If autoblanking terminates before the crosstalk sensing interval reaches a maximum blanking interval, then safety standby pacing is cancelled. Another aspect of the invention relates to monitoring the amount of time in a safety standby sensing window during which signals are detected.
Abstract: An implantable electrical device comprising an RV coil and a pacing probe. The RV coil provides defibrillation and cardioversion waveforms to the heart and the pacing probe provides pacing signals to the heart and also acts as a sensor of the heart's intrinsic activity. The pacing probe is advantageously positioned within the apex of the heart. The device includes a controllable interconnect circuit that interconnects the RV coil and the pacing probe so that when the RV coil provides a defibrillation or cardioversion therapeutic shock to the heart, a portion of the energy provided to the RV coil is provided to the pacing probe so that an electrical shock is simultaneously provided to the apex for defibrillation or cardioversion purposes. In the preferred embodiment, a shunt resistor is positioned in series with the pacing probe so that the current being supplied to the pacing probe is limited.
Abstract: An external surrogate defibrillation electrode is provided that increases the safety of performing implantation testing of implantable cardioverter-defibrillators. The surrogate electrode has an electrode pad that is attached to the patient's skin. If the implantable cardioverter-defibrillator is not capable of providing a sufficiently high-energy defibrillation shock during the implantation procedure, the surrogate electrode attached to the patient's skin can be electrically connected to the implantable cardioverter-defibrillator, thereby allowing the implantable cardioverter-defibrillator to effectively apply a rescue shock to the patient.