Abstract: Methods and apparatus for reducing the incidence of atrial fibrillation includes selecting a desired ventricular rate, pacing the ventricle of the heart at the desired ventricular rate, and pacing the atrium of the heart at twice the desired ventricular rate while the desired ventricular rate is less than a preferred rate. Some methods of the present invention include pacing the atrium of the heart at the desired ventricular rate while the desired ventricular rate is greater than the preferred rate. Other methods of the present invention include pacing the atrium of the heart at a predetermined/preferred atrial rate while the desired ventricular rate is greater than the preferred rate.

Abstract: The present invention provides a method and apparatus for detecting and treating sleep respiratory events that includes a plurality of sensors gathering physiological data related to sleep respiratory events. A processor extracts an average cycle length and a frequency of at least one of Cheyne-Stokes respiration and periodic breathing based upon the physiological data, and determines whether therapy is required based on the average cycle length and the frequency.

Abstract: Methods and apparatus for reducing the incidence of atrial fibrillation includes selecting a desired ventricular rate, pacing the ventricle of the heart at the desired ventricular rate, and pacing the atrium of the heart at twice the desired ventricular rate while the desired ventricular rate is less than a preferred rate. Some methods of the present invention include pacing the atrium of the heart at the desired ventricular rate while the desired ventricular rate is greater than the preferred rate. Other methods of the present invention include pacing the atrium of the heart at a predetermined/preferred atrial rate while the desired ventricular rate is greater than the preferred rate.

Abstract: The present invention provides a method and apparatus for detecting and treating sleep respiratory events that includes a plurality of sensors gathering physiological data related to sleep respiratory events. A processor extracts an average cycle length and a frequency of at least one of Cheyne-Stokes respiration and periodic breathing based upon the physiological data, and determines whether therapy is required based on the average cycle length and the frequency.

Abstract: An apparatus and method for detecting micro-dislodgment at a heart tissue/pacing lead electrode interface involves measuring a first pacing threshold parameter at a first time in a patient's cardiac cycle and measuring a second pacing threshold parameter at a second time in the patient's cardiac cycle. Micro-dislodgment occurring at the heart tissue/pacing lead electrode interface is detected using the first and second pacing threshold parameters. Micro-dislodgment may be detected by comparing a difference between, or a ratio of, the first and second pacing threshold parameters to a preestablished maximum allowable deviation value. A difference between the first and second pacing threshold parameters or a ratio in excess of the preestablished maximum allowable deviation value indicates a problem at the heart tissue/pacing lead interface.

Abstract: A pacing system provided with a mode switching feature and ventricular rate regularization (VRR) function adapted to stabilize or regularize ventricular heart rate during chronic or paroxysmal atrial tachyarrhythmia. In a preferred embodiment, the pacing system nominally operates in an atrial synchronized pacing mode such as DDD or DDDR pacing mode. In response to detection of atrial rhythm characteristics consistent with an atrial tachyarrhythmia, e.g., atrial fibrillation, a mode switch into a non-atrial synchronized, ventricular rate regularization pacing mode, e.g. DDIR or VDIR pacing mode, is made. If the VRR function is programmed on, the ventricular pacing rate based upon a rate responsive sensor derived ventricular pacing rate modulated on a beat by beat basis by preceding intrinsic or paced ventricular events, the stability of the intrinsic ventricular heart rate, and any atrial pace events to regularize the ventricular pacing rate.

Abstract: A length of living conductive cells may be injected directly or may be grown to be attached to a fibrous matrix of material that provides for flexible structure so as to deliver a stimulation signal from one end of the biologic cable to the other to induce a physiologic reaction in body tissue.

Abstract: An automatic, body-implantable medical device having at least two modes of operation is disclosed. The device is provided with circuitry for automatically detecting when the device has been implanted in a patient, so that the device can automatically switch from a first mode to a second mode of operation upon implantation. In one embodiment, the first mode is a power conserving mode in which one or more non-essential sub-systems of the device are disabled. Prior to detection of implant, at least two conditions of the device known to reflect whether the device has been implanted are monitored. After implant has been detected, situations in which power to the device is disrupted and then restored will cause the device to enter a predefined "power-on-reset" mode of operation. Prior to detection of implant, however, such conditions do not result in the device entering the power-on-reset mode, or this mode is reset.

Abstract: A method and apparatus for automatic determination of a pacemaker patient's pacing stimulation threshold. Circuitry is provided in a pacemaker for obtaining a signal reflecting cardiac impedance, which is known to reliably reflect certain aspects of cardiac function. Circuitry is also provided for monitoring the cardiac impedance waveform during a predetermined capture detect window following delivery of stimulating pulses. One or more values are derived which characterize the morphology of the impedance waveform during the capture detect window associated with each stimulation pulse delivered. These values are compared to predetermined control values in order to assess whether a stimulation pulse has achieved cardiac capture. The assessment of whether cardiac capture has been achieved is also based partly upon the conventional sensing of atrial and/or ventricular cardiac signals occurring during the capture detect window.

Abstract: An AV search method and apparatus is taught with some variation described. It allows a pacemaker to find the appropriate AV interval so as to avoid pacing in the ventricle when it is not necessary, even if there is intermittent AV conduction in the patient. Also, an adaptive PVARP method and apparatus is disclosed that allows the PVARP and AV interval to be adjusted together automatically.

Abstract: A method and apparatus for automatic determination of a pacemaker patient's pacing stimulation threshold. Circuitry is provided in a pacemaker for obtaining a signal reflecting cardiac impedance, which is known to reliably reflect certain aspects of cardiac function. Circuitry is also provided for monitoring the cardiac impedance waveform during a predetermined capture detect window following delivery of stimulating pulses. One or more values are derived which characterize the morphology of the impedance waveform during the capture detect window associated with each stimulation pulse delivered. These values are compared to predetermined control values in order to assess whether a stimulation pulse has achieved cardiac capture. The assessment of whether cardiac capture has been achieved is also based partly upon the conventional sensing of atrial and/or ventricular cardiac signals occurring during the capture detect window.

Abstract: Some false tachy detection prevention algorithms miss blocked 2:1 sensing and therefore miss some true tachy situations. Here an algorithm that uses sensed far field R waves to determine whether to search for blocked 2:1 sensing is implemented and a search algorithm is also described.

Abstract: A pacemaker control method and apparatus for determining the presence of atrial tachyarrhythmias uses a true interval value and compares it to a predetermined tachy value. The true interval value is updated based on the presence of far field R waves in PVARP that meet certain sequencing criteria. The criteria selected allows the control method and apparatus to reduce or eliminate event sequences that will generate false positive tachy detection and subsequent mode switching, while still allowing for the detection of tachy events in PVARP.

Abstract: A method and apparatus for variable rate cardiac stimulation, wherein sudden drops in the rate of delivery of stimulation pulses are avoided by means of rate smoothing and peak rate support functions. In one embodiment, circuitry in a cardiac pulse generator detects atrial events and maintains an updated value of the A-A time intervals between certain atrial events. If a preset ratio or total of these A-A intervals are found to have been shorter than the updated value by at a least a predetermined amount of time, a rate smoothing function is activated wherein the rate of delivery of stimulating pulses is prevented from changing, from cycle to cycle, by more than a predetermined maximum amount. A peak rate support function preferably employs the same updated value in the computation of "escape" intervals. Following the latest A-A interval, if that A-A interval is less than the updated value, then the updated value is used as the new escape interval.

Abstract: A method and apparatus for automatic determination of a pacemaker patient's pacing stimulation threshold. Circuitry is provided in a pacemaker for obtaining a signal reflecting cardiac impedance, which is known to reliably reflect certain aspects of cardiac function. Circuitry is also provided for monitoring the cardiac impedance waveform during a predetermined capture detect window following delivery of stimulating pulses. One or more values are derived which characterize the morphology of the impedance waveform during the capture detect window associated with each stimulation pulse delivered. These values are compared to predetermined control values in order to assess whether a stimulation pulse has achieved cardiac capture. The assessment of whether cardiac capture has been achieved is also based partly upon the conventional sensing of atrial and/or ventricular cardiac signals occurring during the capture detect window.

Abstract: A dual chamber, rate-responsive pacemaker for pacing a patient's heart novelly allows tracking of the patient's sinus rate when the sinus rate is slightly less than the sensor rate; i.e., within a predetermined "Sinus Preference Window Maximum Rate Drop." Pacing at the sensor rate occurs when the sensor rate exceeds the sinus rate by more than the Sinus Preference Window Maximum Rate Drop. In the preferred embodiment a Sinus Preference Window, which occurs at the end of the ventricle-to-atrium interval, is decremented with successive heart beats by a programmable delta to increase the pacing rate until the Sinus Preference Window reaches zero, in which case the pacemaker paces at the sensor rate. The Sinus Preference Window is reset to its maximum value upon either the detection of an atrial sensed event, or upon the expiration of a programmable Sinus Check Interval.

Abstract: A rate-responsive cardiac pacemaker implements a novel pacing mode, identified as ADIR/VVIR, which is especially effective for patients with Sick Sinus Syndrome and only intermittent atrioventricular block. Within the same pacemaker circuitry, an AAIR pacemaker and a VVI pacemaker (with an escape rate below that of the AAIR pacemaker) are provided with atrial blanking following both atrial and ventricular events. Ventricular blanking after atrial pacing is minimized for better detection of R-waves following an atrial paced event.

Abstract: A dual chamber, rate-responsive pacemaker for pacing a patient's heart novelly allows tracking of the patient's sinus rate when the sinus rate is slightly less than the sensor rate; i.e., within a predetermined "Sinus Preference Window Maximum Rate Drop." Pacing at the sensor rate occurs when the sensor rate exceeds the sinus rate by more than the Sinus Preference Window Maximum Rate Drop. In the preferred embodiment a Sinus Preference Window, which occurs at the end of the ventricle-to-atrium interval, is decremented with successive heart beats by a programmable delta to increase the pacing rate until the Sinus Preference Window reaches zero, in which case the pacemaker paces at the sensor rate. The Sinus Preference Window is reset to its maximum value upon either the detection of an atrial sensed event, or upon the expiration of a programmable Sinus Check Interval.

Abstract: A dual chamber pacemaker system and method are provided for HOCM and like pacing therapy, with the feature of searching or scanning values of AV escape interval to define an optimized value at about the longest AV escape interval value consistent with full capture in response to a delivered ventricular pace pulse. In a preferred embodiment of the invention, the system and method sense and process FFRS signals derived from the atrial lead and otherwise, and obtain therefrom a characteristic which is evaluated for a determination of optimized AV escape interval. In one specific embodiment, the time durations between delivered ventricular pacing pulses and resulting FFRS signals are analyzed as a function of AV escape interval, and the optimized AV escape interval is chosen at about the longest AV escape interval corresponding to the longest such time duration, i.e., at about the knee of the FFRS time duration vs. AV escape interval curve.

Abstract: A method and apparatus for cardiac pacing, in which pacing pulses are provided at an increased rate in response to a detected rapid drop in heart rate. A rapid drop is detected in response to heart rate falling from a persistent rate above a first threshold rate to a stable rate below a second threshold rate. If spontaneous depolarizations are detected while pacing at the increased rate, pacing at the increased rate is terminated.