Abstract: A cardiac rhythm management system includes an implantable medical device capable of delivering cardiac therapy and sensing an EGM. The implantable medical device undergoes threshold testing and transmits testing data to a computer via a remote monitor.

Abstract: Multi-site cardiac pacing systems for providing pacing to multiple sites in a patient's heart, e.g., in a single heart chamber or in right and left heart chambers, while avoiding inappropriate responses to double sensing of an evoked depolarization conducted between the sites. A conditional refractory period and further post-event time periods, e.g. a conventional refractory period, are started upon a sense event or pacing pulse sensed at or delivered to a first pace/sense site. A sense event detected at another sense site that occurs during the conditional refractory period is characterized as a conditional refractory event, and it restarts shortened post-event time periods and terminates the conditional refractory period. The restarted post-event time periods are reduced in length by the elapsed time between the starting and termination of the conditional refractory period.

Abstract: A pacing system for selectively sensing spontaneous ventricular cardiac depolarizations at first and second spaced apart ventricular sites during the time-out of an AV delay and delivering pace pulses to the spaced apart ventricular sites in a triggered pacing mode. The first and second ventricular sites are preferably right ventricular (RV) and left ventricular (LV) pace/sense electrode sites, and RV event and LV event signals are sensed at the RV and LV pace/sense electrodes. A V-A pacing escape interval and a ventricular refractory period, a trigger pace window, an upper rate interval and further post-event time periods are started upon a RV or LV sense event or a first ventricular pace pulse delivered upon time-out of the AV delay. A triggered ventricular pace pulse or pulses is delivered to one or both of the RV and LV pace/sense electrode sites upon detecting an RV sense event or LV sense event during the AV delay.

Abstract: Multi-site cardiac pacing systems for providing pacing to multiple spaced apart sites of a patient's heart, including especially but not limited to sites in right heart chamber (RHC) and left heart chamber (LHC), in triggered pacing modes while avoiding inappropriate delivery of triggered pacing to the RHC and/or LHC on a non-refractory sense event that occurs early in the cardiac cycle.

Abstract: A system for pacing in a right and its corresponding left heart chamber provides a predetermined or programmable triggered delay in a predetermined or programmable, right-to-left or left-to right sequence without first determining from which of the two chambers a triggering event originated. Devices that provide cardio defibrillation today often have pacemakers for delivering adjunct therapies, and such devices can also use the invention.

Abstract: A body-implantable rate-responsive cardiac pacemaker is provided with circuitry for sensing a plurality of physiologic parameters known to be indicative of a patient's metabolic demand for increased cardiac output. In one embodiment, a rate-responsive pacemaker is provided with an activity sensor for detecting the patient's level of physical activity, and is further provided with an impedance sensing circuit for detecting the patient's level of minute ventilation by monitoring cardiac impedance. A rate-response transfer function, implemented by the pacemaker's control circuitry, periodically computes a rate-responsive pacing rate as a function of the outputs from both physiologic sensing circuits. The pacemaker's pacing rate is variable within a rate range defined by predetermined (programmable) upper and lower limits. In the preferred embodiment, the influence of activity sensing and minute ventilation parameters varies in accordance with the current pacing rate.

Abstract: A method and apparatus for determining the availability of unipolar and/or bipolar pacing/sensing paths in a body-implantable cardiac pacing system. In one embodiment, a pacemaker system includes impedance monitoring circuitry for periodically measuring impedance between pairs of electrodes that are potentially available for pacing and/or sensing. This impedance monitoring circuitry includes circuitry for delivering excitation pulses between pairs of potentially available electrodes (including the pacemaker canister in the case of unipolar pacing or sensing), and for monitoring the current and voltage between those pairs of electrodes during delivery of an excitation pulse. Availability of a pair of electrodes for pacing and/or sensing is indicated if the impedance between a pair of electrodes is found to lie within a predetermined range.