Abstract: The system and method discriminates P-waves or other electrical events originating in the atria from R-waves or other electrical events originating in the ventricles. In one example, far-field R-waves in the atria are distinguished from true P-waves using both a post-ventricular atrial blanking (PVAB) interval and a separate pre-ventricular blanking interval (pre-VAB) interval. Insofar as the pre-VAB interval is concerned, upon detection of a P-wave in the atria, the implantable medical device begins tracking a pre-VAB interval. If an R-wave is then detected in the ventricles during the pre-VAB interval, the P-wave is rejected as being a far-field R-wave. A PVAB interval may also be employed to filter out any P-waves detected in the atria immediately following detection of an R-wave in the ventricles. In another example, far-field R-waves are distinguished from true P-waves using template matching. P-waves detected in the atria are compared against a template representative of true P-waves.

Abstract: An implantable cardiac lead suitable for placement in any one of a plurality of implant locations of the heart includes an identifier which identifies the implant location of the lead. The lead includes a lead body which carries a plurality of implant location indicators. The implant location indicators may be removable whereby the removal of all but one location indicator provides a unique indication of the lead implant location. The implant location indicators may alternatively be individually selectable to provide a unique indication of the implant location. Still further, the implant location indicators may comprise an implant location identifying system wherein each indicator provides a direct indication of a respective different one of the plurality of implant locations and is configured for individual placement, and for retainment, on the lead.

Abstract: Improved methods and devices perform anti-tachycardia pacing (ATP) to convert a ventricular tachycardia (VT) to normal sinus rhythm. In one embodiment of the invention bi-ventricular (BV) ATP is employed. In this embodiment the right ventricle and left ventricle of a patient's heart are independently paced based on signals sensed in each chamber.

Abstract: An implantable cardiac stimulation device establishes communication with at least first and second external devices which communicate using first and second communication protocols, respectively, and wherein the first and second protocols are different. The implantable device includes a pulse generator configured to generate stimulation pulses and a telemetry circuit arranged to establish communication with the first and second external devices according to the first and second communication protocols, respectively. A control circuit coupled to the telemetry circuit and the pulse generator detects the first and second external devices based upon the protocol used in establishing communication to provide a first response when the first external device is detected and a second response when the second external device is detected.

Abstract: Methods and systems for monitoring heart rate recovery are described. In one embodiment, an implantable monitoring device monitors a patient's heart activity. The monitor looks for periods of increased activity, such as those that are experienced during some level of exercise, and periods of lesser activity (such as rest) directly following. The patient's heart rate recovery is monitored as the heart recovers from the active period to the rest period. Data associated with the patient's heart rate recovery can then be diagnostically used to ascertain certain conditions associated with the patient.

Abstract: A multi-chamber stimulation device and associated method reliably and automatically distinguish fusion from loss of capture during ventricular stimulation. The stimulation device provides immediate and accurate fusion detection when a loss of capture is suspected in the ventricles without delivering back-up stimulation pulses. To achieve this objective, the far-field signal present in the atrial channel is examined for evidence of a far-field R-wave whenever the ventricular channel detects a loss of capture. If a far-field R-wave is present, fusion is confirmed, and a far-field R-wave is absent, loss of capture is confirmed. Additionally, the stimulation device inhibits unnecessary back-up stimulation and threshold tests when fusion occurs, and provides appropriate adjustment of stimulation parameters based on confirmed fusion detection such that fusion re-occurrence is minimized.

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: Dynamic overdrive pacing adjustment techniques are described for use in implantable cardiac stimulation devices. In a first technique, an overdrive pacing unit of a microcontroller of the implantable device operates to optimize various control parameters that affect overdrive pacing so as to achieve a desired degree of overdrive pacing for the particular patient in which the stimulation device is implanted. Parameters to be optimized include the number of overdrive beats paced once overdrive pacing is trigged, the overdrive pacing response function, the recovery rate, and various base rates. The control parameters are adjusted in a hierarchical order of priority until the desired degree of overdrive pacing is achieved. Adjustment of the number of overdrive beats, the recovery rate, and various base rates is iteratively performed by using incremental numerical adjustments.

Abstract: An implantable cardiac stimulating device employs an automatic defibrillation threshold tracking process that uses a measured pacing stimulation threshold to estimate the patient's defibrillation threshold on a dynamic, ongoing basis, using changes in the defibrillation threshold to re-calculate new defibrillation parameters (e.g., energy settings) on a periodic basis as a patient's heart changes over time. The defibrillation threshold estimation formula may involve a variety of variables, such as, for example, the patient's age and/or gender, and may include a selected safety margin. New defibrillation parameters are loaded into the appropriate locations of the device's memory, replacing the prior parameters, and are thereafter available for use by the device for defibrillation therapy. The defibrillation threshold tracking technique may be used in an external device, such as a programmer or external cardiac stimulation device.

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 associated method set an atrial capture detection window by verifying that inter-atrial conduction is intact, and then measuring the inter-atrial conduction time. The measured inter-atrial conduction time may then be used for setting the atrial capture detection window. Capture verification of a stimulated atrial site is then implemented by detecting a conducted depolarization at another atrial site or in the opposite atrial chamber. A signal received during an atrial capture detection window is compared to a depolarization signal threshold or to a depolarization signal template in order to verify detection of a conducted depolarization signal as evidence of capture at the stimulated site. By sensing depolarization signal away from the stimulated site, the negative effects of lead polarization normally encountered when detecting an evoked response are avoided.

Abstract: An implantable cardiac device is programmed to detect an episode of sleep apnea, measure the duration of the episode, and store this information in memory. When multiple episodes are recorded, the device computes statistics on the apnea durations, such as average apnea duration and total apnea duration for a preselected time period (e.g., 8-hour rest period, 24-hour day, etc.). The implantable cardiac device may further be used to administer pacing therapy in response to detecting sleep apnea. Under the control of a physician, the implantable device may be programmed to administer different types of responsive therapies to evaluate whether certain therapies are more effective at treating apnea than others. For instance, a pacing therapy that results in lowering the average apnea duration or total apnea duration may be preferred over other pacing therapies that do not achieve such results.

Abstract: An exemplary electrode portion, capable of placement in a vessel of a patient's body, includes a double helix. Exemplary implantable stimulation devices, lead assemblies and methods are also disclosed.

Abstract: An implantable cardiac stimulation device and method provide a histogram for storing the number of primary and backup stimulation pulses delivered at each amplitude setting, to monitor the performance of the automatic capture verification. The stimulation device delivers cardiac stimulation therapy in which a stimulation histogram advantageously stores the number of primary pulses delivered at each stimulation output, or range of outputs, and separately stores the number of high-energy backup stimulation pulses delivered. Knowing the historical frequency of the applied stimulation amplitudes is useful to a physician in selecting future stimulation pulse output settings and the working margin. This information is also useful in determining the expected remaining battery life. The stimulation histogram further provides a useful diagnostic tool for evaluating the integrity of the stimulation device, lead system and performance of the automatic capture algorithm.

Abstract: An implantable programmable cardiac stimulation device and associated method for differentiating between normal sinus events and ectopic beats. The stimulation device monitors the sensing thresholds of sinus and non-sinus cardiac events, and stores a history of these sensing thresholds along with temporal data for accurate event detection. The stimulation device further provides accurate and appropriate detection of sensed events including P-waves, non-conducted PACs, and conducted PACs and thus verifies correct detection of PVCs and R-waves. Furthermore, the present invention provides a history record of ectopic events, distinguished by sensing thresholds and timing intervals, giving a valuable diagnostic tool to the physician in optimizing rhythm management therapy. In addition, the stimulation device allows the sensitivity threshold to be set based on a single cardiac cycle and past history.

Abstract: A cardiac stimulation device and method detect myocardial ischemia and provide a response for alleviating the ischemia. Myocardial ischemia is detected by identifying changes in the ST-segment of the intracardiac electrogram (EGM) sensed using large sensing electrode surfaces created by electrically coupling one or more cardiac electrodes or by using larger surface area shocking coils. Myocardial ischemia monitoring is performed when stimulation parameters are adjusted for increasing cardiac output, causing an increased metabolic demand to be placed on the myocardium itself. When myocardial ischemia is detected, stimulation parameters are re-adjusted to reduce the demand placed on the myocardium and thereby alleviate the ischemia.

Abstract: A cardiac stimulation device and method automatically confirm capture by detecting the polarity of a post-stimulation signal. A capture detection circuit is subjected to recharge and block overlap signals applied such than an evoked response signal is characterized by a primarily positive polarity and a polarization signal is characterized by a primarily negative polarity. An amplitude detection feature, such as peak amplitude or signal integral, and its polarity are determined from a post-stimulation signal sensed by the capture detection circuit during a capture detection window. Capture is confirmed when the amplitude detection feature has a positive polarity.

Abstract: A connector assembly includes a ring sub-assembly mounted on the housing of an implantable medical device with a passage for slidably receiving a proximal terminal of an electrical lead. The interior of the connector assembly is sealed when engaged with the electrical lead and has an annular shoulder in the passage facing away from the entrance. An electrical contact on the ring sub-assembly engages the electrical lead and an electrical conductor extends from that contact to exterior regions for electrical engagement with an external feed-through terminal of the housing. A tip sub-assembly having a tubular extremity extending to a terminal rim is fittingly received within the passage and extends to a terminal bore for slidably receiving a tip electrode of the electrical lead. An electrically conductive resilient member is received in the passage sandwiched between the annular shoulder and the terminal rim of the tubular extension and is electrically coupled to the electrical contact of the connector assembly.

Abstract: The stimulation device blanks T-waves from the atrial channel of an electrical cardiac signal by employing a T-wave blanking interval localized to the expected location and duration of the T-wave. To this end, the stimulation device determines the average interval between an R-wave and a T-wave in the patient in which the device is implanted and also determines the average duration of a T-waves within the patient. A T-wave blanking interval is initiated following the average R-T interval subsequent to detection of an R-wave and lasts for a period of time equal to the average T-wave duration. In this manner, highly localized T-wave blanking is achieved permitting P-waves or other atrial signals to be detected during remaining non-blanked portions of the atrial channel of the cardiac signal at least for the purposes of atrial rate detection. The relatively short T-wave blanking interval of the invention is particularly well suited for use in combipolar sensing systems.

Abstract: An implantable cardiac stimulation device, such as a pacemaker, defibrillator and/or cardioverter, and an associated method that provide cardiac stimulation to at least two ventricular stimulation sites, within a single ventricle or across two ventricles. A high intrinsic atrial rate triggers a retrograde conduction detection routine when a high ventricular stimulation rate is sustained for a predetermined number of cycles during an atrial sensing mode. This routine interrupts concurrent stimulation, and alternates the stimulation output to the different ventricular sites.