Abstract: Techniques for detection and treatment of myocardial ischemia are described that monitor both the electrical and dynamic mechanical activity of the heart to detect and verify the occurrence of myocardial ischemia in a more reliable manner. The occurrence of myocardial ischemia can be detected by monitoring changes in an electrical signal such as an ECG or EGM, and changes in dynamic mechanical activity of the heart that are sensed by an accelerometer sensor. The heart acceleration signal can be obtained from an single- or multiple-axis accelerometer and/or a pressure sensor deployed within or near the heart. The techniques correlate contractility changes detected by an accelerometer or pressure sensor with changes in the ST electrogram segment detected by the electrodes to increase the reliability of ischemia detection.

Abstract: In an implantable medical device a real-time left atrial pressure (“LAP”) signal obtained from a patient's heart is used as a feedback control mechanism to adjust one or more device parameters. In one example the device identifies specific characteristics and attributes of the LAP signal that correlate to hemodynamic performance, and adjusts the device parameters to optimize the LAP characteristics and attributes. In a dual-chamber pacing system, the controlled operating parameter may include the atrioventricular pacing delay, and LAP attribute suitable for controlling the atrioventricular pacing delay time intervals of v-wave, a-wave, and/or c-wave characteristics of the LAP signal.

Abstract: Improved pacing thresholds for capturing the heart are achieved by forming a discontinuity in the cardiac tissue of the heart chamber, disposing a pacing electrode at a distance less than a space constant of the cardiac tissue from the discontinuity in the cardiac tissue, and applying a stimulus of a first polarity at an energy insufficient to cause the directly stimulated tissue adjacent to the pacing electrode to propagate a depolarization wave through the cardiac tissue mass of the heart chamber but sufficient to induce a transmembrane potential change at the tissue adjacent to the discontinuity that results in a propagated wave front. Thus, pacing energy is advantageously reduced.

Abstract: An electrical feedthrough assembly according to the invention can be used as a component of an implantable medical device (IMD) and/or or electrochemical cell. An IMD includes implantable pulse generators, cardioverter-defibrillators, physiologic sensors, drug-delivery systems, etc. Such assemblies require biocompatibility and resistance to degradation under applied bias current or voltage. In some forms of the invention, such assemblies are fabricated by using electrically common, multiply-interconnected electrical pathways including metallized vias and interlayer structures of conductive metallic material within bores and between ceramic layers. The layers are stacked together and sintered to form a substantially monolithic dielectric structure with at least one electrically common embedded metallization pathway extending through the structure.

Abstract: An implantable medical device communication system communicates information between an implantable medical device and at least one slave device by way of a two-wire bus. Slave devices may include remote sensors, actuators and other implantable medical devices. The implantable medical device includes a communication unit to output commands and power pulses, and receive information from the slave devices over the two-wire bus. The implantable medical device and slaves communicate over the bus by selectively changing one of the lines of the bus between a first and second voltage, the second voltage substantially equal to a reference voltage of the second line, e.g., zero volts. In some embodiments, the power pulses take the form of bipolar pulse pairs. The slave device includes a recovery unit to recover power from the power pulses.

Abstract: In an atrial pacing system, the A-PACE pulse energy, defined by the pulse width and pulse amplitude, sufficient to reliably capture the atrium without being wasteful of battery energy is periodically determined in accordance with atrial capture management (ACM) algorithms. The ACM algorithms allow a slow intrinsic atrial heart rate that is suppressed by delivered A-PACE pulses resulting in A-CAPTURE and that occurs when delivered test A-PACE pulses result in ALOC to be detected. ALOC is declared if an A-EVENT of the slow intrinsic atrial heart rate is detected either during an ACM test window timed from the last delivered test A-PACE pulse or during delivery of a sequence of test A-PACE pulses delivered within or defining the ACM test window correlated to the slow intrinsic atrial heart rate.

Abstract: In general, the invention is directed towards techniques for adaptively prioritizing cardiac episode data in a memory of an implanted medical device (IMD). More specifically, the IMD receives new cardiac episode data, assigns each piece of data a priority value, and stores the data in a memory of the IMD. The IMD can further recalculate initial priority values assigned to stored cardiac episode data in response to subsequent cardiac episode data. In this manner, the prioritization scheme used by the IMD is adaptive, i.e., changes as more contextual information regarding the cardiac episode and subsequent cardiac episodes becomes available. Upon exceeding a memory capacity threshold, the IMD identifies the stored cardiac episode data with a lowest priority from the hierarchical priority relationship, and overwrites the identified portion of the stored cardiac episode data with the new cardiac episode data.

Abstract: An implantable medical device delivers augmentation therapy to intervene in a pattern of sleep-disordered breathing. Augmentation therapy includes the delivery of electrical stimulation to cardiac tissue above and/or below a capture threshold. PESP and NES/CCM are possible augmentation therapies that are used alone or in combination. In addition, augmentation therapies can be used with other pacing therapies such as atrial overdrive pacing and atrial coordinated pacing as a therapy for sleep-disordered breathing.

Abstract: A system and method is provided for reliably indicating that an implantable medical device is in need of replacement. The system and method measures the operational characteristics of the battery and the operational parameters of the implantable device itself. When these characteristics and parameters reach a defined level, the implantable medical device starts a replacement indicator timer. The replacement indicator timer starts and counts a replacement time period, with the replacement time period ending at a determined replacement date. The determined replacement date is the date at which the implantable medical device should be replaced.

Abstract: There are many different serious cardiac arrhythmias. The present invention uses measurements of RR intervals (interbeat intervals) to detect, in particular but not exclusively, atrial fibrillation of a patient. Atrial fibrilation is a serious ailment in which the heartbeat is generally rapid and irregular. Probability density histograms of ?RRs (difference between two successive RR intervals) collected during atrial fibrillation of a plurality of subjects are used as a template for the detection of atrial fibrillation. In one implementation, there are 16 standard probability density ?RRs histograms every 50 ms of mean RR interval of a certain number of beats, where the mean RR interval ranges from 350 ms to 1149 ms. Similarity between the standard probability density histograms and a test density probability histogram of ?RRs of a patient is estimated by the Kolmogorov-Smirnov test.

Abstract: A steerable elongated medical device adapted to be advanced through a tortuous pathway to a desired location in a body includes an outer tube extending between an outer tube proximal segment and an outer tube distal segment, having an outer tube wall forming an outer tube lumen and an elongated outer tube slot through the outer tube wall to the outer tube lumen. The elongated outer tube slot has a first portion and a second portion and is formed between an outer tube slot proximal end and an outer tube slot distal end and extending axially along the outer tube distal segment through an outer tube slot length to define a cutaway portion of the outer tube.

Abstract: The present invention relates to monitoring septal wall motion of the atrial and/or ventricular chambers of a heart for optimizing cardiac pacing intervals based on signals derived from the monitored wall motion. At least one lead of medical device is equipped with a motion sensor adapted to couple to septal tissue. The device receives and may post-process (e.g., suitably filter, rectify and/or integrate) motion signals to determine acceleration, velocity and/or displacement. During pacing interval optimization the wall motion is measured for those pacing intervals and the pacing interval setting(s) that produce minimal wall motion for chronic therapy delivery. In addition, methods for periodically determining whether to cease or resume delivery of a bi-ventricular pacing therapy to a patient that may have experienced beneficial reverse remodeling of the heart.

Abstract: The present invention includes a “Z shaped” configuration for a pair of internal windings of a fiber core of a medical electrical lead which can be configured as or windings to provide counter-rotation an implanted cardiac lead. When fully assembled and implanted within a patient, a screw-type active fixation electrode, such as a helical electrode, electrically couples to a coil conductor and mechanically couples to a loop formed at an end of the Z-shaped braided fiber. To remove the lead, an axial traction force is applied and as the Z-shaped braids begin to unwind rotational forces operate to unscrew the helical electrode. A lead constructed according to the present invention rotates counterclockwise and thus essentially unscrews the active fixation electrode.

Abstract: The invention is directed to lead configurations for sensors that allow for less invasive sensor replacement procedures. In one configuration, a sensor lead assembly includes an outer lead body and an inner lead including a sensor such as an electrochemical glucose sensor. The inner lead can be positioned in an inner conduit of the outer lead body. The outer lead body may be substantially permanently implanted in the patient, and the inner lead can be implanted through the inner conduit of the outer lead body. Once the sensor of the inner lead has worn out or otherwise exhausted its useful life, the inner lead can be removed, and a new inner lead can be implanted in place of the old inner lead.

Abstract: A system for writing data efficiently between a fast clock domain and a slow clock domain. In one embodiment, a processor that performs firmware routines is clocked by a fast clock that is turned on when a prescribed event occurs to operate in the fast clock domain in conjunction with hardware that performs certain device operations that is clocked by a slow clock that is always on to operate in a slow clock domain. Writing data from the processor to the hardware involves determining if a bit is to be written to a register of the slow clock domain in synchrony with a transition of the slow clock, stopping the fast clock to pause operation of the processor, writing the bit to the register of the slow clock domain upon a succeeding slow clock transition, and starting the fast clock to resume operation of the processor.

Abstract: Conductive aerogels are employed in fabrication of electrical medical leads adapted to be implanted in the body and subjected to bending stresses. An elongated, flexible and resilient, lead body extends from a proximal end to a distal end and includes an insulative sheath having an elongated lumen through which an elongated conductor extends. A layer of conductive aerogel is disposed over the conductor deforming upon movement of the conductor within the lumen against the aerogel in response to applied stresses.

Abstract: The present invention provides a method and apparatus for remotely programming implantable medical devices. The apparatus includes a server adapted to receive and store at least one request to modify the behavior of an implantable medical device provided by a programmer adapted to allow a clinician to create the at least one request at a first selected time. The apparatus further includes a monitor adapted to receive the requests from the server and transmit the requests to the implantable medical device at a second selected time and a bi-directional communications system adapted to couple the server and the monitor.

Abstract: A cardioverter/defibrillator of the type having at least one high voltage (HV) output capacitor having valve metal anode and cathode electrodes with an oxide formed over a majority of said anode and a wet electrolyte in fluid communication with the electrodes that is charged from a battery through a charging circuit including a HV step-up transformer and is adapted to be discharged through cardioversion/defibrillation (C/D) electrodes is disclosed. The HV output capacitor(s) periodically charge in a reform charge cycle to substantially a maximum or full charge at a reform charge rate slower than a C/D therapy charge rate, which also charges said HV output capacitor(s) to the maximum or full charge, to thereby reform deformed portions of the oxide.

Abstract: An isolated heart preparation in which essentially normal pumping activity of all four chambers of the heart is preserved, allowing for the use of the preparation in conjunction with investigations of electrode leads, catheters, cardiac implants and other medical devices intended to be used in or on a beating heart. The preparation may also be employed to investigate heart functions, in the presence or absence of such medical devices. In order to allow for visualization of heart structures and devices located within the chambers of the heart, a clear perfusate such as a modified Krebs buffer solution with oxygenation is circulated through all four chambers of the heart and the coronary vasculature. The preparation and recordings of the preparation may be used in conjunction with the design, development and evaluation of devices for use in or on the heart, as well as for use as an investigational and teaching aid to assist physicians and students in understanding the operation of the heart.

Abstract: A stacked die package is formed by stiffening a flexible substrate, arranging a chip mounting pattern on one side of the substrate, and mounting chips according to the arranged pattern. A solder ball array on the opposite side of the substrate is routed to the chips, and the flexible substrate and stiffener are folded to align the chips in the stacked die package. The stiffener is removed by a single saw cut.