Abstract: The present invention is directed to an electrolytic capacitor having a novel floating anode between the cathode and the powered anode of the capacitor, resulting in a single capacitor having a working voltage double that of the formation voltage of the powered anode. The floating anode acts as cathode to the powered anode and as an anode to the cathode, such that the capacitor according to the present invention supports half the working voltage between the cathode and the floating anode and half the working voltage between the floating anode and the powered anode. The arrangement of the cathode, floating anode and powered anode according to the present invention results in a single capacitor with half the capacitance and twice the voltage of a single anode device.

Abstract: The present invention is directed to a method of creating porous anode foil for use in multiple anode stack configuration electrolytic capacitors, producing a pore structure that is microscopic in pore diameter and spacing, allowing for increased energy density with a minimal increase in ESR. Initially, an anode metal foil is etched, according to a conventional etch process, to produce an enlargement of surface area. The etched foil is then placed into the electrochemical drilling solution of the present invention. Alternatively, the etched foil may be masked, so that only small areas of the etched foil are exposed, prior to being placed in the electrochemical drilling solution. A DC power supply is used to electrochemically etch the masked or unmasked foil in the electrochemical drilling solution of the present invention such that pores on the order of a few microns diameter are produced through the foil.

Abstract: A 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. A determination is made whether a reentrant loop responsible for the VT is closer to one or the other of the pacing/sensing electrode pairs. ATP is performed with the pair of electrodes closest to the reentrant loop.

Abstract: Cardiac performance associated with a current set of N pacing parameters is improved by adjusting the cardiac pacing parameters until optimal or substantially optimal cardiac performance is achieved. The cardiac performance associated with the current set of N pacing parameters is determined. An incrementing step, a determining step, and a increment updating step, are repeated for i=1 to N, where i represents which of the N pacing parameter is being adjusted. The incrementing step includes incrementing an ith pacing parameter in the current set of N pacing parameters based on a corresponding ith increment value, to thereby produce an ith set of test pacing parameters. The determining step includes determining a cardiac performance associated with the ith set of test pacing parameters. The increment updating step includes updating the ith increment value based on the cardiac performance associated with the ith set of test pacing parameters.

Abstract: The present invention is directed toward an enhanced very high volt electrolyte for use in electrolytic capacitors. In particular, by the inclusion of a polymer matrix of a hydrogel, preferably of the family of poly(hydroxy alkyl methacrylate) but also including polyvinylalcohol (PVA), polyacrylonitrile (PAN), into a standard fill electrolyte, the breakdown voltage of the enhanced very high volt electrolyte of the present invention is raised to as much as 800 V. An electrolytic capacitor impregnated with the enhanced very high volt electrolyte of the present invention, is capable of operating at a voltage of 700 to 800 volts. The production of a very high volt capacitor capable of operating at a voltage of 700 to 800 volts allows a single high volt electrolytic capacitor to replace the conventional two capacitors-in-series arrangement of an Implantable Cardioverter Defibrillator (ICD).

Abstract: An improved method and device for performing anti-tachycardia pacing (ATP) to convert a ventricular tachycardia (VT) to normal sinus rhythm. Pacing/sensing electrodes are implanted in or on the left and right ventricles of a patient's heart. After a VT is detected a determination is made based on the shape of the electrogram signal of the VT. One of a plurality of time offsets for pacing pulses of the left and right ventricles is selected based on the signal shape and ATP is performed by pacing both the left and right ventricles with the time offset between pulses in the respective ventricles.

Abstract: An implantable cardiac stimulation device is equipped with a sensor to obtain information indicative of tissue depolarization. The device's processor is programmed to analyze the information to determine a suitable pacing pulse regimen and/or to trigger a cardioversion level stimulus.

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: The present invention is directed to a conductive electrolyte for use in 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 two solvent mixture of ethylene glycol and a polar organic cosolvent. Dissolved in this mixture is a combination of: a high dielectric cosolvent, a long chain monocarboxylic acid and an aliphatic dicarboxylic acid of carbon chain length from eight to thirteen (C8 to C13). The solution is then neutralized with an amine. A cathode depolarizer, or degassing agent may be added to reduce the amount of gas produced during capacitor life. Hypophosphorous acid may be added to enhance the life characteristics of the electrolyte. The water content may be adjusted with deionized water to achieve a Karl Fischer titration (water content) measurement of about 1.0% to about 8.

Abstract: The present invention is directed to a conductive electrolyte for use in 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 two solvent mixture of ethylene glycol and a polar organic cosolvent from the group of 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, hexyl alcohol, or di(ethylene glycol). Dissolved in this mixture is a combination of boric acid with either an aliphatic dicarboxylic acid of carbon chain length from eight to thirteen (C8 to C13) or a very long chain dicarboxylic acid, where the acid functional groups are separated by 34 carbons (referred to as “dimer acid”). The solution is then neutralized with an amine.

Abstract: The present invention is directed to a method of etching anode foil in a non-uniform manner which increases the overall capacitance gain of the foil while retaining foil strength. In particular, by using a mask to protect a mesh grid of the foil from further etching, a previously etched foil can be further etched, prior to the widening step. Alternatively, the mask may be used in the initial etch, eliminating the need for the second process. In effect the foil may be etched to a higher degree in select regions, leaving a web of more lightly etched foil defined by the mask to retain strength. According to the present invention, the foil is placed between two masks with a grid of openings which expose the foil in these areas to the etching solution. The exposed area can be as little as 10% of the total foil to as much as 95% of the total foil, preferably 30% to 70% of the total foil area.

Abstract: A time-varying modulating signal is used as a plethysmography signal, rather than a time-varying detected optical power. The time-varying detected optical power is used (e.g., in a feedback loop) to adjust the source intensity. Light is transmitted from a light source, wherein an intensity of the transmitted light is based on a light control signal. A portion of the light transmitted from the light source is received at a light detector, the portion having an associated detected light intensity. A feedback signal is produced based the portion of light received at the light detector, the feedback signal indicative of the detected light intensity. The feedback signal is compared to a reference signal to produce a comparison signal. The light control signal is then adjusted based on the comparison signal, wherein at least one of the comparison signal and the light control signal is representative of volume changes in blood vessels.

Abstract: Improved methods and devices for performing anti-tachycardia pacing (ATP) to convert a ventricular tachycardia (VT) to normal sinus rhythm. In one embodiment one of a plurality of pacing configurations are selected for performing ATP. The selection can be based on the morphology of a signal indicative of the tachycardia.

Abstract: An implantable cardiac rhythm management device has a flexible circuit sheet with a number of connected sheet portions and a number of conductive traces extending between different sheet portions. A plurality of device components are attached to the sheet, on different sheet portions. The sheet is articulated at fold lines between the sheet portions; and folded so that at least some of the sheet portions occupy different planes.

Abstract: The present invention is directed to a method of encasing electrolytic capacitor stacks or wound rolls to form an external package. First, a plastic sheet is heated to its soft transition temperature. Next, the plastic sheet is draped over a preassembled capacitor stack or wound roll. Then, a vacuum is applied to the capacitor stack or wound roll, such that the sheet is formed around the stack or wound roll. Finally, the plastic sheet is allowed to cool. This process results in a vacuum formed plastic capacitor case assembly which minimizes wasted volume in the capacitor package and minimizes capacitor assembly time.

Abstract: An active feedback loop is provided in a switched-capacitor circuit to automatically cancel both junction and sub-Vth channel leakage. Low power consumption that is crucial for implantable medical devices is achieved. The circuit technique largely minimizes the effective leakage current when the switch is turned off. This circuit technique of the invention can be used in many different circuit applications.

Abstract: In an arrhythmia discrimination algorithm a timer is used to trigger the delivery of therapy when no diagnosis is made within a defined time during a tachycardia episode. Where one or more rhythm discriminators or qualifiers such as morphology, sudden onset, interval stability and AV association is enabled, the timer starts as soon as a ventricular interval or interval average is faster than a programmed maximum time to diagnosis (MTD) cutoff. If the timer times out before the algorithm diagnoses a particular rhythm, a programmed therapy is delivered. In the preferred embodiment, the therapy that is triggered is a function of the most recent detected ventricular rate and the programmed MTD therapy.

Abstract: A method for monitoring the condition of a heart failure patient using respiration patterns is provided. An implantable or other ambulatory monitor senses the patient's respiratory patterns to identify the presence of periodic breathing or Cheyne-Stokes respiration. In a first embodiment, mechanical changes of the thorax due to breathing are detected and this data is used to recognize hyperventilation and apnea or hypoventilation. In a second embodiment of the invention, Cheyne-Stokes respiration is recognized by detecting changes in blood or tissue pH or CO2 concentration and partial pressure. In another embodiment of the invention, changes in pulse amplitude associated with Cheyne-Stokes respiration are detected. Alternating loss and return of respiration-induced amplitude modulation or pulse-interval variation may also be used to identify the presence of Cheyne-Stokes respiration.

Abstract: Detection and monitoring of periodic breathing (PB) to provide an indication of changes in the hemodynamic status of a heart failure patient is accomplished by monitoring at least one of four independent physiologic parameters. The physiologic parameters are respiratory tidal volume, respiratory rate (B-B interval), arterial oxygen saturation (SaO2) and heart rate (R-R interval). The data collected of these physiologic measures may then be analyzed by performing power spectral analysis or thresholding/binning. Each analysis method can be applied to each measure or combination thereof. In the preferred embodiment, the physiologic measures are made when the patient has been identified as being at rest or asleep to prevent interference from activity-related respiratory variations.

Abstract: The present invention is directed to a high voltage, highly conductive electrolyte for use in 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 two solvent mixture of ethylene glycol and N-methylformamide; a combination of hypophosphorous acid, boric acid and an aliphatic dicarboxylic acid of carbon chain length from eight to twelve, such as azelaic, sebacic, or brassylic acid; an amine including ammonia, ammonium hydroxide, diethylamine, dimethylamine, triethylamine, or triethanolamine; and a nitro-substituted aromatic compound as a degassing agent, such as 3′-nitroacetophenone. Anhydrous ammonia may also be added to neutralize the solution.