Abstract: Techniques and circuits are described for approximation of the differential capacitance of a capacitive sensor to, among other things, optimize device operation and power consumption. In particular, feedback techniques are utilized for measurement and approximation of the differential capacitance of the capacitive sensor. In accordance with the disclosure, the capacitance approximation value for a test cycle preceding a given test cycle is utilized to reduce the number of iterations to be performed in a continuous series of test cycles. The capacitance approximation value for the given test cycle is reported as being equivalent to that of the preceding test cycle if the variance between the selected capacitance and the unselected capacitance is less than or equal to a first predefined value.

Abstract: Devices, systems, and techniques for selecting a period for charging an implantable rechargeable power source are disclosed. Implantable medical devices may include a rechargeable power source that can be transcutaneously charged. A system may control a charging module to begin charging the rechargeable power source of the implantable medical device with a high power level. The system may then determine an estimated heat loss based on power initially delivered to the rechargeable power source when beginning the charging. Based on this estimated heat loss during the initial period of recharging, the system may select a boost period that includes a duration of time that the rechargeable power source is charged with the high power level.

Abstract: Methods and apparatus for storing data records associated with a medical monitoring event in a data structure. An implanted device obtains data and stores the data in the data record in a first data structure that is age-based. Before an oldest data record is lost, the oldest data record may be stored in a second data structure that is priority index-based. The priority index may be determined by a severity level and may be further determined by associated factors. The implanted device may organize, off-load, report, and/or display a plurality of data records based on an associated priority index. Additionally, the implanted device may select a subset or composite of physiologic channels from the available physiologic channels based on a selection criterion.

Abstract: An implantable medical device (IMD) is implanted in a patient. The IMD uses a plurality of electrode vectors to generate intrathoracic impedance measurements. The intrathoracic impedance measurements can be indicative of amounts of intrathoracic fluid in the patient. An accumulation of intrathoracic fluid may indicate that the patient is at an increased risk of experiencing a heart failure event in the near future. The IMD performs a vector selection operation on a recurring basis. When the IMD performs the vector selection operation, the IMD uses impedance measurements to select one of the electrode vectors. The IMD can perform a risk assessment operation on another recurring basis. During performance of the risk assessment operation, the IMD uses impedance measurements of the selected electrode vector and/or other patient characteristics stored within the IMD to determine whether the patient is at an increased risk of experiencing a heart failure event.

Abstract: This document discusses, among other things, examples of a low profile instrument immobilizer and means for positioning the same. In one example, the low profile instrument immobilizer grasps, secures, and immobilizes an electrode or other instrument that extends through a burr hole in a skull to a target location in a patient's brain.

Abstract: Bioelectrical signals may be sensed within a brain of a patient with a plurality of sense electrode combinations. A stimulation electrode combination for delivering stimulation to the patient to manage a patient condition may be selected based on the frequency band characteristics of the sensed signals. In some examples, a stimulation electrode combination associated with the sense electrode combination that sensed a bioelectrical brain signal having a relatively highest relative beta band power level may be selected to deliver stimulation therapy to the patient. Other frequency bands characteristics may also be used to select the stimulation electrode combination.

Abstract: An implantable medical device for optically sensing action potential signals in excitable body tissue. The device includes an elongated tubular lead body carrying an optical fiber extending from a proximal lead end to a distal lead end to position the optical fiber at a target site. The lead body additionally carries a conduit for dispensing a voltage-sensitive fluorescent dye into tissue surrounding the target site. The optical fiber transmits excitation light to the fluorescent dye to cause the dye to fluoresce with varying intensity as the transmembrane potentials of local tissue cells vary due to passing depolarization wavefronts. The optical fiber transmits the fluorescence signal to the device to generate an action potential signal or fiducial points of an action potential signal for use in accurately measuring and characterizing electrical activity of excitable tissue.

Abstract: An improved medical electrical lead is disclosed herein. The lead may include a longitudinally extending body having a distal end, a proximal end, a conductive element extending between the distal and proximal ends, and an electrode coupled to the conductive element utilizing a reflow process. The conductive element and electrode may comprise materials that are incompatible.

Abstract: High range activated clotting time (HR-ACT) tests detect blood clotting time in blood samples which have high levels of heparin. Reagents such as calcium chloride and kaolin within the test apparatus trigger clotting. Physical separation of the reagents from each other prevents interaction between them before the test sample introduction. In one embodiment, to improve dry kaolin re-suspension, kaolin may be suspended in water rather than buffered saline before being dispensed into the test chamber. The combination of removing the buffered saline and the calcium chloride from the kaolin suspension enables clot detection in blood samples containing 5-6 u/ml of heparin.

Abstract: Methods and/or devices may be configured to monitor ventricular activation times and modify an atrioventricular delay (AV delay) based on the monitored ventricular activation times. Further, the methods and/or devices may determine whether the AV delay should be modified based on the measured activation times before modifying the AV delay.

Abstract: In one example, a device includes a telemetry module configured to retrieve graphics processing data from a device that is not configured to perform a rendering process using the graphics processing data and that is associated with delivering therapy to a therapy target of a patient, and a control unit configured to apply the graphics processing data while performing the rendering process to generate an image of an anatomical feature of the patient, wherein the anatomical feature comprises the therapy target for an implantable medical device, and to cause a display unit of a user interface to display the image, wherein the image of the anatomical feature is specific to the patient. The graphics processing data may include a list of vertices or a transform to be applied to a non-patient-specific anatomical atlas. The data may also include a location of a therapy element of the implantable medical device.

Abstract: An SRAM having two capacitors connected in series between respective bit storage nodes of each memory cell. The two inverters of the memory cell are powered by a positive voltage and a low voltage. The two capacitors are connected to each other at a common node. A leakage current generator is coupled to the common node. The leakage current generator supplies to the common node a leakage current to maintain a voltage which is approximately halfway between the voltages of the high and low SRAM supplies.

Abstract: A catheter proximal section is preferably formed from a relatively soft part and a relatively rigid part, and includes a proximal terminal end that defines a perimeter of an opening into a lumen of the catheter. The proximal section may further include a feature for interlocking engagement with an accessory tool. An inner surface of each of the relatively soft and rigid parts may be located opposite one another, on either side of the catheter lumen. The relatively soft and rigid parts may be included in a sealing assembly that further includes an attachment feature for removable connection of the assembly to the proximal section catheter.

Abstract: Random access memory having a plurality of memory cells, each of the plurality of memory cells having a memory element and a first electrical characteristic being variable based, at least in part, on temperature and a bias circuit operatively coupled to at least one of the plurality of memory cells, the bias circuit being configured to generate a bias voltage for the at least one of the plurality of memory cells. The bias circuit has a second electrical characteristic being variable based, at least in part, on temperature. The first electrical characteristic is approximately proportional to the second electrical characteristic over a predetermined range of temperatures, the predetermined range of temperatures being greater than zero. The bias voltage on each of the plurality of memory cells is approximately proportional with variations in the first electrical characteristic over the predetermined range of temperatures.

Abstract: A method for monitoring the effectiveness of VSR and for taking action to improve the effectiveness of VSRs, if they are determined to be ineffective, includes comparing the a VSR evoked electrogram to a template electrogram of a pure biventricular paced CRT beat. If the electrograms, or features thereof, are similar, the VSR is determined to be effective. If the VSR is determined to be ineffective, the AV delay of biventricular CRT is shortened in a step-wise fashion in an incremental manner.

Abstract: Methods and/or devices may be configured to track effectiveness of pacing therapy by monitoring activation times over time, e.g., between pacing stimulus and electrical activity resulting from the pacing stimulus. Generally, the methods and/or devices may determine whether the delivered pacing therapy was effective based on the measured activation times.

Abstract: A rechargeable lithium-ion battery includes a housing including a titanium or a titanium alloy, a positive electrode having a first capacity and at least one positive active material selected from the group consisting of LiCoO2, LiMn2O4, LiNiO2, LiCoPO4, LiCoPO4F, LiFeMn2-xO4, LiAlxCoyNi(1?x?y)O2, and LiTixCoyNi(1?x?y)O2, a negative electrode having a second capacity that is less than the first capacity, such that the battery has a negative-limited design, and a negative active material that is configured to cycle lithium ions at a potential of greater than approximately 0.2 volts versus a lithium reference electrode, a liquid electrolyte including a lithium salt dissolved in at least one non-aqueous solvent, and a porous polymeric separator located between the positive electrode and negative electrode and configured to allow lithium ions to flow through the separator.

Abstract: A heart valve assembly includes a base including a multi-lobular annular shape within a plane, a valve member or other annular body including a multi-lobular shape complementary to the shape of the base, and cooperating connectors on the base and the annular body for connecting the annular body to the base. The base includes an anchoring ring, and a flexible cuff for attaching the base to a biological annulus. The base and the annular body include guides for aligning their multi-lobular shapes, e.g., visual, tactile, or other markers, or tethers that extend from the base that are slidable through the annular body. During use, the base is attached to a biological annulus, the annular body is directed adjacent the annulus, oriented such that the multi-lobular shape of the annular body valve member is aligned with the base, and the annular body is attached to the base.

Abstract: Methods and/or devices may be configured to monitor the performance of pacing therapy and provide fault-tolerant operation to provide therapy in the event of certain failure modes occurring in the pacing delivery circuits, leads, and/or lead/tissue interfaces. Generally, the methods and/or devices may provide fault-detection, fault-recovery and fault-handling to, e.g., handle potential faults.

Abstract: In general, the invention is directed to a technique for percutaneously introducing a stimulation lead into a target stimulation site via the epidural region proximate the spine of a patient. The process of introducing the stimulation lead may include the use of a hollow stimulation lead introducer, which comprises an elongated sheath and an elongated dilator. The dilator fits within the sheath and serves to widen a path through the epidural region for the introduction of a stimulation lead. At least a portion of the stimulation lead introducer has an oblong cross-section, allowing passage of stimulation leads such as paddle leads. The stimulation lead introducer may enter the epidural region proximate a spine of a patient via a guidewire. The stimulation lead introducer provides a path through the epidural region of a patient to a target stimulation site. A stimulation lead may travel through the path to reach the target stimulation site where it may provide therapy to the patient.