Abstract: A power control circuit for an implantable medical device is presented. The power control circuit includes a first high rate cell, a second high rate cell, at least one resistive load, and at least one control circuit. The at least one resistive load is connected between the first and the second high rate cells. The at least one control circuit is coupled to the first and the second high rate cells.

Abstract: An intracardiac electrogram (IEGM) or other suitable electrical cardiac signal is sensed. Values representative of a pre-symptomatic physiologic response to a hypoglycemic event are derived from the cardiac signal. Then, hypoglycemia is detected based on the values representative of the pre-symptomatic physiologic response. In one example, both temporal morphological parameters and spectral parameters affected by pre-symptomatic hypoglycemia are derived from the cardiac signal. Hypoglycemia is then detected based on a combination of the temporal and spectral parameters using, e.g., a linear discriminator. By detecting hypoglycemia based on parameters affected by pre-symptomatic hypoglycemia, suitable warnings can be generated and therapies initiated before the condition becomes symptomatic.

Abstract: An implanted device is equipped with a flag that indicates to a remote monitoring unit that an event such as a patient medical emergency or device failure has occurred. The remote monitoring unit is configured in some embodiments to maintain a low power communication link with the implanted device when they are within range. When the flag indicates an event has occurred, the remote monitoring unit quickly downloads sensed data collected by the implanted device and transfers it over a network so that it can be utilized by a medical practitioner. The remote monitoring unit is further configured in some embodiments to query the implanted device at regular intervals. The remote monitoring unit may read a subset of the data stored by the implanted device and, based on that data, determine whether to complete a full or partial download.

Abstract: A method of stimulating tissue of a patient is provided. The method comprises placing an array of electrodes in proximity to the tissue, conveying electrical current between the electrodes of the array to stimulate a tissue site, incrementally shifting the electrical current from at least one cathode to at least another cathode over a first range of fractionalized current values, and incrementally shifting the electrical current from at least one anode to at least another anode over a second range of fractionalized current values. The step sizes for the first and second ranges of fractionalized current values differ.

Abstract: A method and device provide for determining capture in multiple chambers of a patient's heart using an electrode inserted into a coronary vein of the patient's heart. The coronary vein electrode is positioned adjacent to multiple heart chambers and is responsive to cardiac signals originating in the multiple chambers. The coronary vein electrode may be coupled to a single sense amplifier to detect the cardiac signals. Pace pulses may be applied to multiple heart chambers simultaneously or according to a phased timing sequence. Cardiac signals responsive to the pace pulses sensed using the coronary vein electrode may be used to verify capture in the multiple chambers of the heart.

Abstract: Guide catheters for facilitating implantation of cardiac leads for applying electrical stimulation to and/or sensing electrical activity of the heart through one or more electrodes positioned at an implantation site within a heart chamber or cardiac vessel adjacent a heart chamber. Such a cardiac lead has low torqueability and pushability through a pathway to enable attachment of the cardiac lead at the implantation site. The catheter body comprises a delivery lumen to introduce a small diameter cardiac lead and a guide lumen to receive a guide tool to locate the catheter body distal end at the implantation site. The small diameter lumen within a small diameter guide tube extends distally from the delivery exit port of the delivery lumen. The catheter body is shaped to bias the delivery lumen exit port toward the heart.

Abstract: Methods and devices for identification of intrinsic ventricular activity occurring within a ventricular signal. Ventricular signal morphology is analyzed to determine if the signal contains intrinsic ventricular activity while delivering pacing pulses separated by nearly constant time intervals. Furthermore, an extension of a pacing interval is specified based on whether or not the signal contains autonomous intrinsic ventricular activity. In this manner, the pacing interval is only extended when it is likely for autonomous intrinsic ventricular activity to occur.

Abstract: A cochlear implant processing strategy increases speech clarity and provides higher temporal performance. The strategy determines the power spectral component within each channel, and dynamically selects or de-selects the channels through which a stimulation pulse is provided as a function of whether the spectral power of the channel is high or low. “High” and “low” are estimated relative to a selected spectral power, for example. The selected spectral power can be estimated by signal average or mean, or by other criteria. Once a selection of the channels to stimulate has been made, the system can decide that only those channels are stimulated, and stimulation is removed from the other channels. The selected channels are the ones on which the spectral power is above the mean of all the available channels. Fewer channels are stimulated at any time and the contrast of the stimulation is enhanced.

Abstract: A combined electrical and chemical stimulation lead is especially adapted for providing treatment to the spine and nervous system. The stimulation lead includes electrodes that may be selectively positioned along various portions of the stimulation lead in order to precisely direct electrical energy to ablate or electrically stimulate the target tissue. Embodiments of the stimulation lead include single or multiple lead elements. The multiple lead element embodiments can be selectively deployed to cover a targeted area. The lead may also includes central infusion passageway(s) or lumen(s) that communicates with various infusion ports spaced at selected locations along the lead to thereby direct the infusion of nutrients/chemicals to the target tissue. One embodiment utilizes a dissolvable matrix for infusion as opposed to remote delivery through an infusion pump.

Abstract: Improvement in the reliability of segmentation of a signal, such as an ECG signal, is achieved through the use of duration constraints. The signal is analysed using a hidden Markov model. The duration constraints specify minimum allowed durations for specific states of the model. The duration constraints can be incorporated either in the model itself or in a Viterbi algorithm used to compute the most probable state sequence given a conventional model. The derivation of a confidence measure from the model can be used to assess the quality and robustness of the segmentation and to identify any signals for which the segmentation is unreliable, for example due to the presence of noise or abnormality in the signal.

Abstract: An implantable medical device (IMD) identifies suspected non-lethal ventricular arrhythmia, and takes one or more actions in response to the identification to avoid or delay delivery of a defibrillation or cardioversion shock. The IMD employs number of intervals to detect (NID) thresholds for detection of ventricular arrhythmias. When a NID threshold is met, the IMD determines whether the ventricular rhythm is a suspected non-lethal rhythm despite satisfying a NID threshold. In some embodiments, the IMD increases the NID threshold, i.e., extends the time for detection, in response to identifying a rhythm as a suspected non-lethal rhythm, and monitors subsequent ventricular beats to determine if the increased NID threshold is met before detecting a ventricular arrhythmia and delivering therapy. The IMD can determine whether a rhythm is a suspected non-lethal arrhythmia by, for example, comparing the median ventricular cycle length (VCL) to the median atrial cycle length (ACL).

Abstract: A cardiac rhythm management (CRM) system provides for post-myocardial infarction (MI) therapy with closed-loop control using one or more ultrasound transducers sensing one or more ultrasound signals indicative of cardiac dimensions. Cardiac size parameters are produced using the one or more ultrasound signals to represent, for example, cardiac chamber diameter, cardiac chamber volume, cardiac wall thickness, infarct size, and degree of change in any of these parameters over time or between measurements. In various embodiments, such cardiac size parameters provide for titration, safety check, and acute optimization of the post-MI therapy.

Abstract: Cardiac monitoring and/or stimulation methods and systems provide for monitoring, diagnosing, defibrillation and pacing therapies, or a combination of these capabilities, including cardiac systems incorporating or cooperating with neuro-stimulating devices, drug pumps, or other therapies. Embodiments relate generally to implantable medical devices employing automated cardiac activation sequence monitoring and/or tracking for arrhythmia discrimination. Embodiments are directed to devices and methods involving sensing a plurality of composite cardiac signals using a plurality of implantable electrodes. A source separation is performed using the sensed plurality of composite cardiac signals and the separation produces one or more cardiac signal vectors associated with one or more cardiac activation sequences that is indicative of ischemia. A change of the one or more cardiac signal vectors is detected using the one or more cardiac signal vectors.

Abstract: An implantable system control unit (SCU) includes means for measuring tissue impedance or other condition to determine allograft health, in order to predict or detect allograft rejection. The SCU also includes at least two electrodes coupled to means for delivering electrical stimulation to a patient within whom the device is implanted, and may also include a reservoir for holding one or more drugs and a driver means for delivering the drug(s) to the patient. In certain embodiments, the system is capable of open- and closed-loop operation. In closed-loop operation, at least one SCU includes a sensor, and the sensed condition is used to adjust stimulation parameters. Alternatively, this sensory “SCU” sounds an alarm, communicates an alarm to an external device, and/or is responsive to queries regarding sensed information, such as tissue impedance.

Abstract: Methods for monitoring laminar coordination in ventricular repolarization and for utilizing the results of such monitoring in cardiac disease diagnosis and treatment. The methods include providing and administering a cardiac function test such as an EKG for examining human cardiac function. The cardiac function test in turn includes making a measurement of at least one marker. Healthy laminar coordination during repolarization is indicated by a measurement which meets an indicated threshold of measurement for the at least one marker. Malfunctioning laminar coordination is indicated by a measurement that does not meet the indicated threshold of measurement for the at least one marker. Malfunctioning laminar coordination is detected by locating a measurement that does not meet the indicated threshold of measurement for the at least one marker as an indication of malfunctioning laminar coordination within results of the cardiac function test. An electronic pacemaker may be employed as a treatment modality.

Abstract: Methods of using unidirectionally propagating action potentials (UPAPs) for cavernous nerve stimulation and for certain disorders are provided. Stimulators capable of creating such UPAPs include, but are not limited to, miniature implantable stimulators (i.e., microstimulators), possibly with programmably configurable electrodes. A method of stimulating a cavernous nerve includes providing at least one implantable stimulator with at least two cathodic electrodes; programming stimulation parameters for the cathodic electrodes to radially steer an electric field generated by the cathodic electrodes to apply stimulation that unidirectionally propagates action potentials along a cavernous nerve; and applying the stimulation to the cavernous nerve in accordance with the stimulation parameters to generate orthodromic action potentials traveling in one direction along the nerve, thereby limiting side effects of bidirectional stimulation.

Abstract: A probe including at its distal extremity a tubular flexible sheath core supporting at least a winding forming a shock electrode and connected to a electrical conductor of connection extending in a internal lumen of the sheath core. The sheath core extends axially without a solution of continuity in the area supporting the winding. In particular, the sheath core comprises cavities to receive and hold conducting inserts, of homologous size with cavities formed locally close to the ends of the winding, the insert being connected to the interior side to the electrical conductor, and on the external side to the corresponding extremity of winding. A longitudinal slit connects the two cavities and allows, by elastic deformation of the sheath core, the introduction into the cavities and in the internal lumen of the unit formed by the final extremity of the electrical conductor beforehand equipped with its two inserts.

Abstract: Cardiac therapy systems include multiple electrodes respectively positionable at multiple left ventricular electrode sites. A pulse generator is coupled to the electrodes and configured to deliver a cardiac resynchronization therapy (CRT). A processor is configured to measure, for each left ventricular electrode site, a timing interval between first and second cardiac signal features associated with left ventricular depolarization. The timing interval is associated with a degree of responsiveness of each left ventricular electrode site to CRT. The processor is configured to determine a pacing output configuration that provides improved patient responsiveness to CRT based on the timing interval measurements and to select at least one left ventricular electrode site from the plurality of left ventricular electrode sites based on the timing interval measurements. The processor may be configured to monitor for a change in hemodynamic status of the patient based on a change in the timing interval.

Abstract: Cardiac monitoring and/or stimulation methods and systems provide monitoring, diagnosis, and defibrillation and/or pacing therapies. A signal processor receives a plurality of composite signals associated with a plurality of sources, performs a source separation, and produces one or more cardiac signal vectors associated with all or a portion of one or more cardiac activation sequences based on the source separation. A method of signal separation involves detecting a change in a characteristic of the cardiac signal vector relative to a baseline. One or more vectors and/or activation sequences may be selected, and information associated with the vectors and/or activation sequences may be stored and tracked.

Abstract: A method for transitioning electrical energy in steps between electrodes implanted within a patient to stimulate tissue (e.g., spinal cord tissue) is provided. The method comprises determining a maximum comfortable step size, determining a minimum step size, selecting one or more step sizes between the maximum comfortable step size and the minimize step size, and transitioning the electrical energy between the electrodes using the selected one or more step sizes.