Abstract: An implantable antiarrhythmia device which detects and classifies arrhythmias of the human heart, and delivers appropriate therapy. The device employs a method of arrhythmia classification based on a set of prioritized rules, each of the rules defining a plurality of criteria based upon characteristics of sensed depolarizations of heart tissue, each rule being met when the criteria associated with the rule are met. Some rules, when met, trigger delivery of antiarrhythmia therapy. Other rules, when met, inhibit delivery of antiarrhythmia therapy. The rules may be met simultaneously, and if so, the highest priority rule governs the behavior of the device.

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-tachyarrhythmia device which delivers anti-tachyarrhythmia therapies to a patient's heart in response to detection of tachyarrhythmias. The device defines first criteria indicating the presence of atrial tachycardia and second criteria indicating the presence of atrial fibrillation, and compares the time elapsed since the either the first or second criteria were initially met to a defined time duration. In response to the defined duration having passed and either of the first or second criteria being met, the device triggers delivery of an appropriate anti-tachyarrhythmia therapy. The timer is reset on detection of termination of atrial tachyarrhythmia, but not on failure of the first and second criteria to be met. The first and second criteria are defined such that they can not be concurrently met.

Abstract: An implantable antiarrhythmia device which detects and classifies arrhythmias of the human heart, and delivers appropriate therapy. The device employs a method of arrhythmia classification based on a set of prioritized rules, each of the rules defining a plurality of criteria based upon characteristics of sensed depolarizations of heart tissue, each role being met when the criteria associated with the role are met. Some rules, when met, trigger delivery of antiarrhythmia therapy. Other rules, when met, inhibit delivery of antiarrhythmia therapy. The rules may be met simultaneously, and if so, the highest priority rule governs the behavior of the device.

Abstract: An antitachyarrhythmia device employing a tachycardia termination methodology in which antitachycardia pacing and cardioversion pulse therapies are combined. After detection of an arrhythmia which would normally result in delivery of a cardioversion or defibrillation pulse, the device begins to charge high voltage output capacitors. During the charging period, the device deliveries an antitachycardia pacing pulse regimen, in an attempt to terminate the arrhythmia prior to delivery of the cardioversion or defibrillation pulse. Following delivery of the antitachycardia pacing pulse regimen, the device evaluates the heart rhythm to determine whether the tachyarrhythmia has terminated. If so, delivery of a high voltage cardioversion or defibrillation pulse is aborted. If the tachyarrhythmia has not terminated, the high voltage pulse is delivered.

Abstract: A sensor for measurement of one or more parameters of arterial blood flow, located on a transvenously inserted lead. The sensor may be inserted into a vein that is anatomically adjacent to the artery in which blood flow parameters are to be monitored, rather than into the artery itself. The sensor may take the form of a set of spaced electrodes for impedance plethysmography, a piezoelectric pulse sensor or a pulse Doppler sensor for detecting arterial blood flow. By measuring arterial blood flow from an adjacent vein, problems associated with insertion of the sensor into the arterial system may be avoided. The sensor may be used to control the characteristics of an implantable device, such as an implantable pacemaker/cardioverter/defibrillator, an implantable drug dispenser or a rate responsive pacemaker.

Abstract: An apparatus for detecting, identifying and treating tachyarrhythmias. Tachyarrhythmias are detected and identified by the use of overlapping ranges of intervals. Provisional identification of tachyarrhythmia is accomplished by measuring and tracking intervals within two overlapping or adjacent interval ranges. Further classification and identification of tachyarrhythmias is accomplished by determining the relative numbers of intervals within a preceding series falling within a third interval range, overlapping one or both of the interval ranges. In response to identification of the tachyarrhythmia, an appropriate therapy is selected and delivered.

Abstract: An implantable cardioverter including apparatus for measuring the width of a patient's R-wave in order to determine whether or not to deliver an antitachycardia therapy. The means for measuring the width of the R-wave comprises a digitizing means for converting electrical signals from the ventricle to digital signals and means for analyzing the digitized signals to determine the end points of sensed R-waves. End points are identified in response to the occurrence of a series of sequential digitized signals which differ from proceeding signals by more than a predetermined amount, and the width of the R-wave is defined as the interval between the first such identified end point associated with a detected R-wave and the last such detected end point associated with the same detected R-wave.

Abstract: An implantable cardioverter/defibrillator provided with method and apparatus for discrimination between ventricular tachycardia and ventricular fibrillation. The device is provided with two pairs of electrodes, each pair of electrodes coupled to processing circuitry for identifying a predetermined fiducal point in the electrical signal associated with a ventricular depolarization. The cumulative beat to beat variability of the intervals separating the two identified fiducal points, over a series of detected depolarizations is analyzed. The result of this analysis is used to distinguish between ventricular tachycardia and ventricular fibrillation.

Abstract: An implantable cardioverter capable of delivering pacing and cardioversion level therapies. The device distinguishes between stable and unstable ventricular tachyarrhythmias by monitoring the progression of atrial cycle lengths during the detected ventricular tachyarrhythmia. A detected increase in atrial cycle lengths during the early stages of the detected ventricular tachycardia is taken as an indication of hemodynamically unstable ventricular tachycardia.

Abstract: An implantable cardioverter/defibrillator provided with method and apparatus for discrimination between ventricular tachycardia and ventricular fibrillation. The device is provided with two pairs of electrodes, each pair of electrodes coupled to processing circuitry for identifying a predetermined fiducal point in the electrical signal associated with a ventricular depolarization. The cumulative beat to beat variability of the intervals separating the two identified fiducal points, over a series of detected depolarizations is analyzed. The result of this analysis is used to distinguish between ventricular tachycardia and ventricular fibrillation.

Abstract: A dual chamber rate responsive pacemaker with automatic mode switching between the DDD mode, the VVIR mode, and the DDIR mode, based on the difference between the average sensor rate and the average atrial rate. The primary pacing mode of operation is DDD, unless that mode is contraindicated by too great a difference between the average sensor rate and the average atrial rate. When the average sensor rate and average atrial rates are not too different, the DDD mode prevails. During bouts of sustained atrial tachyarrhythmia or atrial oversensing, the average atrial rate is greater than the average sensor rate. When that difference exceeds a programmable function of the two rates, the mode is switched to VVIR to avoid tracking high atrial rates. Conversely, if there is atrial chronotropic incompetence or atrial undersensing, then the average sensor rate is greater than the average atrial rate.

Abstract: A rate responsive pacer which paces the heart at a rate dependent on detected variations in the stroke volume of the heart.