Abstract: An implantable cardiac stimulation device and associated method perform a true or blanking period ventricular undersensing detection algorithm in response to ventricular loss of capture not associated with fusion or a change in capture threshold. The test identifies an originating cause of loss of capture, which may be ventricular undersensing of intrinsic R-waves or premature ventricular contractions occurring during a ventricular blanking period or atrial undersensing of P-waves resulting in blanking period ventricular undersensing. A corrective action is taken to reduce the likelihood of blanking period ventricular undersensing by automatically adjusting device operating parameters. The corrective action may include automatic adjustment of atrial sensitivity, shortening of the ventricular blanking period, or adjustment of the base stimulation rate.

Abstract: An implantable cardiac stimulation device and method measure atrioventricular conduction time and automatically adjust a positive hysteresis interval, for example AV hysteresis or PV hysteresis, to be applied to an AV interval or PV interval during atrial stimulation or atrial sensing, respectively. To measure atrioventricular conduction time during ventricular stimulation, the AV or PV interval is increased until R-wave sensing occurs. The AV or PV interval value at which R-wave sensing occurs is stored in memory as the atrioventricular conduction time. This atrioventricular conduction time is used to calculate a positive hysteresis value by subtracting the programmed AV or PV interval from the conduction time and adding a safety margin. Atrioventricular conduction time measurements are repeated periodically, with or without automatic adjustment of positive hysteresis intervals, and results are stored with time and date information for later display for diagnostic purposes.

Abstract: An implantable stimulator device provides automatic electrode polarity switching during an atrial capture verification mode. In systems using a bipolar sensing configuration in the atrium, polarity switching will be advantageous in detecting far-field R-waves for verification of capture. This automatic polarity switching feature is programmable and enables or disables automatic switching from bipolar to unipolar sensing at the onset of a far-field interval window and switching again back to bipolar pacing at the end of the far-field interval window.

Abstract: An implantable cardiac stimulation system capable of automatic capture verification is provided with an associated method for performing automatic testing functions using programmable, or automatically determined, atrioventricular delays. Automatic threshold testing and evoked response sensitivity testing performed at a user-specified delay setting, rather than a preset setting, allows assessment of automatic capture verification based on an atrioventricular delay relevant to daily system function. Further features of the present invention are an adjustable frequency with which automatic threshold tests are performed and an adjustable frequency with which threshold test results are stored in memory in a threshold record for better monitoring of lead stability or impending clinical problems. The frequency of performing threshold tests and the frequency of storing threshold test results may be varied according to the threshold stability.

Abstract: Location-specific diagnostic information is detected and recorded by the cardiac stimulation device for subsequent display using the external programmer device. The diagnostic information includes location-specific event records, counters and IEGM signals. The event records include event codes that distinguish among events occurring in the four chambers of the heart, such as sensed or paced events occurring within the left or right atria or the left or right ventricles. The counters separately count events occurring within the chambers of the heart. The IEGM signals are separately detected within the four chambers of the heart using a multiple sensing lead arrangement. The location-specific event records, counters and IEGM signals are ultimately transmitted to the external programmer, which displays graphic representations of the diagnostic information. The event records are displayed using distinct event marker icons which distinguish among the four chambers of the heart.

Abstract: An implantable dual chamber stimulation device provides a novel detection scheme that automatically detecting atrial capture and performing an atrial pacing threshold assessment. The stimulation device preferably waits until the patient is at or near rest and monitors the patient's P-wave activity to determine a detection window where a next P-wave is expected to occur. The stimulation device then delivers an atrial pulse prior to the next detection window, and monitors the window to determine whether a P-wave occurs therein. If a P-wave does not occur, then atrial capture is present, while occurrence of a P-wave indicates absence of atrial capture. If atrial capture is absent, the stimulation device automatically determines an appropriate atrial pacing threshold by monitoring the detection window while adjusting the stimulation pulse energy level.

Abstract: An implantable cardiac stimulation device provides long QT interval therapy for preventing abnormal ventricular activation-recovery time and ultimately ventricular arrhythmias. The device includes a sensing circuit that senses intracardiac activity of a heart and that generates electrical signals representing electrical activity of the heart. The device includes a physiologic sensor, such as body motion, or other diurnally varying sensor that reliably detects a diurnal state of the patient (i.e., not the QT interval itself). The device further includes a measuring circuit that measures a QT interval of the electrical signals, a control circuit that determines whether the QT interval is appropriate for the diurnal state, and a pulse generator that delivers pacing pulses to at least one chamber of the heart at a pacing rate when the QT Interval is pathologically too long.

Abstract: A method and assembly for selectively actuating features of implanted medical devices with a magneto-static field. The method includes selectively exposing the implanted device to a static magnetic field source, selectively shielding the magnetic field source, and distancing the shielded magnetic field source from the medical device. One version of the assembly includes a permanent magnet and a displaceable shield assembly that shields the magnetic field generated by the magnet in one configuration and is displaceable to a second configuration wherein the magnetic field is at least partially exposed. In another version, the assembly is an electromagnet that can be selectively activated and deactivated. The electromagnet generates minimal magnet field when it is off.

Abstract: A system and method for identifying and displaying safety alert advisories. The system of the present invention automatically performs a comparison of identification data with a safety alert advisory. The system stores identification data in a plurality of dedicated fields. Each of the dedicated fields contains information related to the patient. Upon the telemetric retrieval of the data by an external programmer, the external programmer automatically cross-correlates the data in the dedicated fields with the safety alert advisories. Upon identification of a match between the data and one of the safety alert advisories, the identified safety alert advisory is displayed to a medical practitioner. In addition, the system provides a dedicated memory to store an advisory flag. The advisory flag is marked when the programmer identifies a safety alert condition that is relevant to one of the dedicated fields.

Abstract: Location-specific diagnostic information is detected and recorded by the cardiac stimulation device for subsequent display using the external programmer device. The diagnostic information includes location-specific event records, counters and IEGM signals. The event records include event codes that distinguish among events occurring in the four chambers of the heart, such as sensed or paced events occurring within the left or right atria or the left or right ventricles. The counters separately count events occurring within the chambers of the heart. The IEGM signals are separately detected within the four chambers of the heart using a multiple sensing lead arrangement. The location-specific event records, counters and IEGM signals are ultimately transmitted to the external programmer, which displays graphic representations of the diagnostic information. The event records are displayed using distinct event marker icons which distinguish among the four chambers of the heart.

Abstract: A pacemaker programmer and diagnostic system retrieves information stored within a pacemaker and analyzes the retrieved data in real time. The stored information can be retrieved by means of a telemetry communication link. The pacemaker automatically lengthens an AV delay. The pacemaker determines atrial capture by generating atrial stimulation pulses while maintaining the ventricular stimulation pulse amplitude at a level known to ensure ventricular capture, and by detecting loss of atrial capture. In response to the loss of atrial capture, a processor automatically records the atrial capture threshold, and restores the AV delay to its pre-test value. The pulse generator also delivers a backup atrial stimulation pulse concurrent with a ventricular stimulation pulse to reduce the possibility of a retrograde P-wave initiating a pacemaker-mediated tachycardia (PMT).

Abstract: An implantable cardiac stimulation device applies defibrillating electrical energy to the atria of a heart at a time which avoids inducing ventricular fibrillation of the heart. The device includes an atrial fibrillation detector that detects atrial fibrillation of the heart, a pacing pulse generator that applies a ventricular pacing pulse to the heart responsive to detection of atrial fibrillation, a timer that times a time period through an evoked response and a T-wave caused by the pacing pulse, and a defibrillation pulse generator that applies defibrillating electrical energy to the atria of the heart after the timer completes the timing of the time period.

Abstract: An implantable cardiac stimulation device and method provides reliable sensing of cardiac events to support cardiac pacing or fibrillation detection. The device comprises a sensing circuit that senses the cardiac events in accordance with a plurality of threshold characterizing parameters. A parameter control adjusts the threshold parameters responsive to the rate of the sensed cardiac events in a manner which precludes positive feedback to prevent continued oversensing, undersensing, or noise sensing.

Abstract: A cardiac stimulation device uses dynamic overdrive pacing to prevent sleep apnea. In another aspect, the device can use dynamic overdrive pacing to terminate sleep apnea after detection. An implantable cardiac stimulation device comprises a sensor and one or more pulse generators. The sensor senses intrinsic cardiac electrical phenomena. The pulse generators can generate cardiac pacing pulses with timing based on the sensed intrinsic cardiac electrical phenomena to dynamically overdrive the intrinsic cardiac electrical phenomena. The timed cardiac pacing pulses can prevent a sleep apnea condition.

Abstract: An implantable multi-chamber cardiac stimulation device includes flexibly programmable electrode stimulation configurations, and is capable of precisely controlling the stimulation sequence between multiple sites. The stimulation device provides a plurality of connection ports that allow independent connection of each electrical lead associated with a particular stimulation site in the heart. Each connection port further provides a unique terminal for making electrical contact with only one electrode such that no two electrodes are required to be electrically coupled. Furthermore, each electrode, whether residing on a unipolar, bipolar or multipolar lead, may be selectively connected or disconnected through programmable switching circuitry that determines the electrode configurations to be used for sensing and for stimulating at each stimulation site.

Abstract: An implantable cardiac stimulation device, programmer, and method provides for automatically evaluating interaction of the implantable device with the patient's heart. The evaluation of the interaction of the device with the patient's heart is based upon analysis of a heart activity signal which may include event markers generated by the implantable device representing applied stimulation pulses and sensed physiological cardiac events. The heart activity signal is analyzed by the programmer and/or implanted device and the operation of the implantable device is automatically adjusted in response to the event heart activity signal analysis. The heart activity signal analysis is also used to determine final evaluation results and completion of the evaluation procedure. The programmer then provides recommendations to the physician as to device programming and/or performs these adjustments automatically.

Abstract: A pacemaker programmer and diagnostic system retrieves information stored within a pacemaker and analyzes the retrieved data in real time. The stored information can be retrieved by means of a telemetry communication link. The pacemaker automatically lengthens a post-ventricular atrial refractory period (PVARP). The pacemaker determines atrial capture threshold by generating atrial stimulation pulses while maintaining the ventricular stimulation pulse amplitude at a level known to ensure ventricular capture, and by detecting loss of atrial capture. In response to loss of atrial capture, a processor automatically triggers a premature ventricular contraction (PVC) response to prevent a retrograde P-wave from initiating a pacemaker-mediated tachycardia. Also in response to loss of atrial capture, the processor sets the atrial stimulation pulse amplitude to a value above the atrial capture threshold in a subsequent cardiac cycle, and restores the PVARP to its pre-test value.

Abstract: Location-specific diagnostic information is detected and recorded by the cardiac stimulation device for subsequent display using the external programmer device. The diagnostic information includes location-specific event records, counters and IEGM signals. The event records include event codes that distinguish among events occurring in the four chambers of the heart, such as sensed or paced events occurring within the left or right atria or the left or right ventricles. The counters separately count events occurring within the chambers of the heart. The IEGM signals are separately detected within the four chambers of the heart using a multiple sensing lead arrangement. The location-specific event records, counters and IEGM signals are ultimately transmitted to the external programmer, which displays graphic representations of the diagnostic information. The event records are displayed using distinct event marker icons which distinguish among the four chambers of the heart.

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: An implantable cardiac stimulation device and associated method perform a true or blanking period ventricular undersensing detection algorithm in response to ventricular loss of capture not associated with fusion or a change in capture threshold. The test identifies an originating cause of loss of capture, which may be ventricular undersensing of intrinsic R-waves or premature ventricular contractions occurring during a ventricular blanking period or atrial undersensing of P-waves resulting in blanking period ventricular undersensing. A corrective action is taken to reduce the likelihood of blanking period ventricular undersensing by automatically adjusting device operating parameters. The corrective action may include automatic adjustment of atrial sensitivity, shortening of the ventricular blanking period, or adjustment of the base stimulation rate.