Abstract: In an implantable cardiac device data is processed and stored to conserve storage space and computational resources thereby saving energy expended on these operations. The data being processed may be associated with signals with known and/or predictable patterns. A set of key elements are identified for the signal that allow the signal to be reconstructed without saving a complete time series of data for the signal.

Abstract: A method and device, such as an implantable cardiac device, for motion and noise immunity in hemodynamic measurement is presented. The method includes obtaining a template waveform representing hemodynamic performance of a heart during a first hemodynamic state and obtaining an autocharacterization measure from an autocharacterization (e.g., autocorrelation) of the template waveform. The method further includes obtaining a test waveform during a second hemodynamic state, performing a cross-characterization (e.g., cross-correlation) of the template waveform and test waveform to identify a cross-characterization measure, and comparing the autocharacterization measure with the cross-characterization measure as a measurement of hemodynamic status of the second hemodynamic state. The device includes hardware and/or software for performing the described method.

Abstract: A battery of a cardiac stimulation device may experience voltage delay problems caused by a passivation layer that forms on the anode of the battery. To inhibit voltage delay, the battery is periodically used to charge the capacitor to a partial charge. Both the charge time and the interval between charges can be adjusted to reduce the power consumption required to inhibit battery voltage delay.

Abstract: Methods, systems and devices are provided for reducing the amount of data, processing and/or power required to analyze hemodynamic signals such as photoplethysmography (PPG) signals, pressure signals, and impedance signals. Methods, systems and devices are also provided for reducing the amount of processing required to determine blood oxygen (O2) saturation levels.

Abstract: The present invention is directed to an electrolyte for use in very high voltage electrolytic capacitors and to an electrolytic capacitor impregnated with the electrolyte of the present invention for use in an implantable cardioverter defibrillator (ICD). The electrolyte according to the present invention is composed of a mixture of an alkoxy-substituted alcohol, such as 2-methoxyethanol, 2-ethoxyethanol, or 2-butoxyethanol, and a long chain dicarboxylic acid, where the acid functional groups are separated by 34 carbons (referred to as “dimer acid”) or 54 carbons (referred to as “trimer acid”). The solution is then neutralized with ammonium hydroxide or other amine, such as ammonia, dimethylamine, trimethylamine, diethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, diisopropylethylamine and N-methylimidazole.

Abstract: An implantable cardiac stimulation device provides bichamber pacing and dynamic bichamber and single chamber sensing. The device includes a sensing circuit that senses activity of a heart, a lead system coupled to a plurality of chambers of the heart, and a cardiac rate circuit that determines a cardiac rate of the heart. A control circuit causes the lead system to couple the sensing circuit to corresponding chambers of the heart to enable bichamber trigger pacing when the cardiac rate is below a given rate and to a single chamber of the heart when the cardiac rate is above the given rate to enable enhanced tachycardia sensing.

Abstract: Receiving an action potential signal associated with a myocardial contraction sensed at a myocardial site, receiving an action potential signal associated with the myocardial contraction sensed at a different myocardial site, comparing a common characteristics of each of the action potential signals wherein the common characteristics relates to at least one member selected from the group consisting of depolarization of tissue at the myocardial sites and repolarization of tissue at the myocardial sites, and, based on the comparing, deciding whether to call for anti-arrhythmia therapy.

Abstract: The ability to continuously monitor concentrations of any of a plurality of blood-borne substances, such as proteins, improves patient monitoring and overall care through early detection of cardiac threats. Ultrasound-based technology used in analytical chemistry to determine amounts of particles suspended in a colloidal composition can be employed in an implantable sensor to monitor levels of many different substances in the blood. A sensor system is implanted in or near a blood vessel in the body and generates an electric or acoustic field directed at that blood vessel. A receiver near the generator detects energy emitted once the assaulting field is turned off. Changes in the relative amounts of the substance(s) being monitored appear as changes in the amount of energy emitted once the assaulting field is removed. The sensor may be implemented in an implantable cardiac therapy device. A non-implantable or transcutaneous sensor may also be used to monitor cardiac health.

Abstract: A method and apparatus for measuring battery depletion in an implantable medical device is presented. The apparatus includes first and second switch pairs disposed in series between the battery and a load, and connected in a parallel arrangement with respect to one another. A capacitor is connected in a first polarity between the battery and the load when only first and fourth switches are closed and in a second polarity when only second and third switches are closed. A comparator circuit causes the switches to reverse the capacitor's polarity based on a comparison of the voltage drop across the capacitor to a threshold value. A counter counts the number of times the capacitor reverses polarity, which is proportional to the amount of charge transferred from the battery during its lifetime in the device and indicative of the battery's level of depletion.

Abstract: A signal indicative of cardiac contractions of a patient's heart is produced, as the patient's heart is paced using different sets of pacing interval parameters. Measures of pulse amplitude are obtained from the signal. Pacing interval optimization is performed based on the measures of pulse amplitude.

Abstract: According the present invention, anode foils are encapsulated in separator material so as to insulate them from the metal housing of an electrolytic capacitor. The present invention also provides for enclosed capacitor configurations for use in stacked capacitor configurations. Preferably, heat-sealable polymeric materials are used as separator materials to encapsulate or enclose the anode assemblies and capacitor configurations. The encapsulated anode assemblies and capacitor configurations of the present invention may be used in implantable cardioverter defibrillators.

Abstract: A parameter in an implantable cardiac therapy device (ICTD) is optimized based on analysis of a hemodynamic signal. The method includes receiving a hemodynamic signal; filtering the hemodynamic signal data to isolate low frequency data present therein; and sampling the low frequency data according to a sampling algorithm. The parameter is optimized in the ICTD based on an analysis of the sampled low frequency data.

Abstract: An improved method and device for performing anti-tachycardia pacing (ATP) to convert a ventricular tachycardia (VT) to normal sinus rhythm. Pairs of pacing/sensing electrodes are placed in or on each of the left and right ventricles. Each pair of electrodes is shorted together to produce unipolar electrodes that are used for ATP.

Abstract: Methods and devices (e.g., pacemakers or ICDs with pacemaker functions) are provided for maintaining a high percentage of bi-ventricular pacing after a pacemaker switches from an atrial tracking bi-ventricular pacing mode to a non-atrial tracking bi-ventricular pacing mode, wherein the ventricles are paced in accordance with a mode switch base rate (MSBR) during the non-atrial tracking ventricular pacing mode. Monitoring is performed to determine whether or not pacing in according with the MSBR satisfies a minimum acceptable pacing criterion (MAPC). The MSBR is increased and pacing is performed in accordance with the increased MSBR, when the MAPC is not satisfied. The MSBR is decreased (e.g., periodically) and pacing is performed in accordance with the decreased MSBR when the MAPC is satisfied.

Abstract: An implantable cardiac device provides a learned premature ventricular contraction density function responsive to detected premature ventricular contractions. A current premature ventricular contraction density is then compared to the learned premature ventricular contraction density function to derive an indication of a condition of a heart and/or to control therapy administered to the heart.

Abstract: A process for producing high stability crystalline anodic aluminum oxide includes anodizing an anodic foil, hydrating the foil, and forming a barrier oxide layer on the foil. Anodizing the anodic foil produces nano-porous amorphous oxides which can then be converted to a crystalline precursor material by hydrating the foil. Next, an oxide layer formation step is utilized to form a barrier oxide layer on the surface of the anodized and hydrated foil. The resulting anodic oxides have very low levels of defects, voids and tensile stresses and have rise times as low as about 1 second to about 3 seconds after exposure of the formed samples to boiling water for 2 hours.

Abstract: The autonomic tone of a patient is measured based on a photo-plethysmography signal that is representative of arterial pulse pressure of the patient. Such measures of autonomic tone can be used to monitor the hemodynamic status of a patient, and even to perform pacing interval optimization. Further embodiments relate to pacing interval optimization performed based on a signal indicative of cardiac contractions of a patient's heart, as the patient's heart is paced using different sets of pacing interval parameters. Such a signal can be a photo-plethysmography signal or an alternative type of signal. Measures of pulse amplitude are obtained from the signal, and pacing interval optimization is performed based on the measures of pulse amplitude.

Abstract: The present invention is directed to a conductive polyethylenedioxythiophene (PEDOT) polymer coated electrode adapted for use as a cathode electrode of an electrolytic capacitor and a method of manufacturing the same. According to the present invention, a metal foil substrate is placed in an aqueous solution of a doped 3,4-ethylenedioxythiophene (EDOT) monomer and a co-solvent, to dissolve the EDOT monomer, and a current is applied until the desired thickness of the polymer coating is electrochemically deposited. Additionally, an organic acid is added to the aqueous solution to act as an oxidizer. In order to improve the uniformity and adherence of the coating a surfactant may also be added. In a preferred embodiment, the EDOT monomer and cosolvent are first mixed, and then added to a water solution of oxidizer and dopant. The polymer film is deposited electrochemically onto the substrate by applying a DC current between 0.05 mA/cm2 and 5.0 mA/cm2 for 1 to 60 minutes, more preferably between about 0.

Abstract: Energy efficient methods and systems for using multi-dimensional activity sensors with implantable cardiac devices are provided. In certain embodiments the output of a passive activity sensor (used for rate responsive pacing) is used to trigger temporary use of a relatively high power multi-dimensional activity sensor. In other embodiments, the output of a relatively low power oxygen saturation sensor is used to trigger temporary use of a relatively high power multi-dimensional activity sensor. This description is not intended to be a complete description of, or limit the scope of, the invention.

Abstract: A method of producing an electrode for use in the manufacture of electrolytic capacitors for implantable cardioverter defibrillators comprises first coating the foil with a photoresist, second, applying a holographic image to the photoresist, third, removing a portion of the photoresist to expose a portion of the foil and create a pattern of photoresist on the foil and etching the foil. Alternatively, the method comprises applying an oxide or metal layer to the exposed foil surface, removing the pattern of photoresist to create a pattern of oxide or metal and etching the foil. The patterns of photoresist, oxide or metal all retard or prevent etching of the foil where the foil surface is covered. This results in a pattern of unetched foil with the remaining area being heavily etched. The resulting patterns stop crack propagation through the etched portions to yield foils with high gain and improved strength.