Abstract: Methods and apparatus for stimulating the right vagal nerve within a living body via positioning an electrode portion of a lead proximate to the portion of the vagus nerve where the right cardiac branch is located (e.g., near or within an azygos vein, or the superior vena cava near the opening of the azygos vein) and delivering an electrical signal to an electrode portion adapted to be implanted therein. Stimulation of the right vagus nerve and/or the cardiac branch thereof act to slow the atrial heart rate. Exemplary embodiments include deploying an expandable or self-oriented electrode (e.g., a basket, an electrode umbrella, and/or an electrode spiral electrode, electrode pairs, etc). Various dedicated and single-pass leads are disclosed, as well as, various electrodes, and stabilization means.

Abstract: A system and method are disclosed for automatically adjusting the sense amplifier sensitivity based on the sensing threshold of the undesired signals (i.e., far-field signals or undesired near-field signals). Specifically, R-wave sensitivity is based on the peak amplitude of the T-waves. Since the relationship between R-waves and T-waves is so repeatable, high confidence is achieved in setting the sensitivity above the T-wave sensing threshold. For atrial sensing, P-wave sensitivity is based on the sensing threshold of R-waves and/or T-waves, whichever is larger. Several embodiments are disclosed for determining the threshold for sensing the undesired signals, such as, double sensing until single sensing occurs, or otherwise detecting the peak amplitude of two or more cardiac signals.

Abstract: An improved system and method for performing automatic capture/threshold detection in an implantable cardiac stimulation device or any device capable of stimulating some body organ or tissue. Prior art systems determine the cardiac tissue's stimulation threshold by detecting an evoked response to a fixed duration stimulation pulse and then increasing the stimulation pulse's amplitude by a predetermined safety margin value. Such systems are inherently based upon a belief that the chronaxie of a particular patient's strength-duration curve is essentially fixed and that the rheobase is variable. While this may be true at some times during the patient's life, e.g., during the acute phase after lead implantation absent drug effects, it is reported that drugs alone may alter the chronaxie and it is believed that other factors may also affect the chronaxie either alone or in combination with the rheobase.

Abstract: An implantable cardiac device, such as a pacemaker or an implantable cardioverter-defibrillator that has a control unit which is adapted to sample a time-varying parameter relating to either the patient's changing physiological condition or to the delivery of therapeutic electrical stimulation pulse to the heart at a sampling frequency. The control unit is adapted to increase the sampling frequency when the variation between successive measurements of the parameter exceed a preselected value. The control unit is further adapted to decrease the sampling frequency when the variation between successive measurements of the parameter are less than a preselected value. In alternate embodiments, the parameter to be sampled is capture threshold, sensing threshold, lead-tissue impedance, and battery performance.

Abstract: An implantable cardiac device, such as a pacemaker or an implantable cardioverter-defibrillator that has a control unit which is adapted to sample a time-varying parameter relating to either the patient's changing physiological condition or to the delivery of therapeutic electrical stimulation pulse to the heart at a sampling frequency. The control unit is adapted to increase the sampling frequency when the variation between successive measurements of the parameter exceed a preselected value. The control unit is further adapted to decrease the sampling frequency when the variation between successive measurements of the parameter are less than a preselected value. In alternate embodiments, the parameter to be sampled is capture threshold, sensing threshold, lead-tissue impedance, and battery performance.

Abstract: Preemptive tachyarrhythmia pacing is provided in an implantable cardiac-stimulation device, such as an implantable pacemaker or defibrillator, by modifying the operation of the implantable device in a way that minimizes the likelihood of occurrence of a tachyarrhythmia. The behavior modification is achieved through the use of an appropriate preemptive tachyarrhythmia pacing control routine stored within the memory of the device. Depending upon the needs of the patient, preemptive tachyarrhythmia pacing is invoked continuously or on demand. If invoked on demand, Preemptive tachyarrhythmia pacing is triggered only upon the sensing of one or more conditions suggest that the onset of a tachyarrhythmia is imminent. When thus invoked, preemptive tachyarrhythmia pacing remains invoked only for as long as the onset-of-a-tachyarrhythmia-is-imminent conditions persist.

Abstract: The present invention is directed toward a pulse generator for detecting that a pulse generator and an implantable lead are properly implanted so that a plurality of automatic features can be automatically turned ON. The automatic features include: automatic sensitivity adjustment; automatic capture adjustment; automatic rate adjustment, and the automatic adjustment of associated rate-responsive parameters; automatic electrode configuration; and the automatic adjustment of other timing parameters. An impedance detector is used to detect that the electrodes are in contact with the body by determining if the lead impedance is within a prescribed range. Redundant sensors, such as a temperature sensor, a shorting plug, or a resistive load could be used to confirm that the electrodes are in contact with the body.

Abstract: A cardiac arrhythmia is terminated by stimulating the heart during the narrow "region of susceptibility" or termination window of the arrhythmia cycle based upon a statistically significant starting value. The present invention will store a plurality of successful critically timed intervals and compute a central value (e.g., average, mean, median, etc.) and a measure of variability (sample range, standard deviation, etc.). The measure of variability is used to determine the termination window size. In one embodiment, the present invention then "scans" symmetrically-centrifugally about the statistically significant starting value. In an alternate embodiment, the present invention employs ranked scanning, that is, scanning according to the frequency of occurrence of previously successful starting values. The number and size of steps could be either programmable, or automatically computed by the pulse generator based upon the termination window size.