Abstract: The present invention is directed toward a very high volt capacitor for use in an implantable cardioverter defibrillator. In particular, by the inclusion of a polymer matrix of a hydrogel, preferably of the family of poly(hydroxyalkylmethacrylate)but also including polyvinyl alcohol (PVA), polyacrylnitrile (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. A very high volt electrolytic capacitor according to the present invention, impregnated with the enhanced very high volt electrolyte of the present invention, is able to support voltages of 700 to 800 volts, while maintaining the described desired properties, and is therefore superior to other known electrolytic capacitors for use in implantable cardioverter defibrillators.

Abstract: An implantable cardiac stimulation device including a ventricular defibrillator and a rate adaptive cardiac pacer automatically adjusts post-pacing sensing parameters dependent upon pacing rate. The device includes a pulse generator that applies stimulation pulses to a heart at a calculated variable stimulation rate as a function of physiologic demand. A sensing circuit senses ventricular activity of the heart responsive to a plurality of sensing parameters including post-pace sensing parameters and a processor adjusts the post-pace sensing parameters responsive to the selected pacing rate.

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: An intravenous cardiac lead having a lumen for delivering a contrast agent as an aid in placement within the coronary sinus or a coronary vein. Also disclosed is a method for advancing such a lead through the right atrium and into the coronary sinus.

Abstract: A system for providing medical electrical stimulation includes a pulse generator coupled to a lead having two electrodes for placement in the right atrium or for placement of one in the right atrium and one in the coronary sinus or coronary vein. In the preferred embodiment the surface area of the first electrode is smaller than that of the second electrode so that the sensed signal from the first electrode is less than that from the second. The system provides dual site pacing with essentially single site sensing without the use of extra switches, connectors, or adaptors.

Abstract: An apparatus for converting capacitance in a capacitive sensor into a voltage signal. A capacitive sensor monitors a physical parameter. A capacitance of the sensor varies with the physical parameter. A voltage supply applies an alternating voltage to the capacitive sensor, which creates an output signal from the sensor. A modulator modulates the output signal, which produces a voltage signal that corresponds to the capacitance of the sensor.

Abstract: A method for detecting an arrhythmia hidden by rapid pacing in a rate adaptive pacemaker/defibrillator. Unmasking a potential arrhythmia is accomplished by lengthening the pace cycle length by a small amount for a number of cycles followed by a shortening of the pace cycle length for the same number of cycles giving an average pacing rate equivalent to the desired rate. This can occur at all times or only when conditions make arrhythmia masking possible. Changing the pace cycle by a small amount over a number of cycles will move the arrhythmia and paced rhythm out of synchronization. Forcing the pacer to continue sensing the arrhythmia is accomplished by insuring that the pacer's sense refractory is less than one half of the pacing cycle length. This is done by constraining the programming of that value to one half the minimum pacing cycle length or using an adaptive sense refractory period.

Abstract: An anode foil treatment method produces a useful high quality oxide with inherently high capacitance at voltages as high as 750 Volts or more. The anode foil treatment method comprises a series of formation and relaxation steps. Oxide layer formation is performed in a forming mixture that includes a high molecular weight dicarboxylic acid that is made into a salt and a strong base. The concentration of the dicarboxylic acid is carefully monitored and kept within a narrow band. The complex by-product of the dicarboxylic salt created during formation process is kept below a fixed maximum level.

Abstract: An electrolytic capacitor with a polymeric housing in the form of a pocket defining a chamber, with an opening along a selected edge. The opening has opposed sides that are sealed together to provide a seam. A number of conductive layers are positioned within the chamber, and a feed-through conductor element has a first end electrically connected to the layers. An intermediate portion of the feed through passes through the seam, and an external portion extends from the housing. The housing may be vacuum formed high density polyethylene, with the feed-through contained in an elastomeric sleeve having a flattened cross section to be readily received in the seam, and to accommodate thermal expansion differences between the housing and the feedthrough. The device may be manufactured by inserting a stack of layers in the pocket, and thermally welding across the opening of the pocket on a single weld line.

Abstract: Methods and apparatus for achieving atrial defibrillation in a heart. Atrial pacing is first conducted from multiple pacing sites in an independent (asynchronous) manner so as to have the desired effect of maximizing the extent of phase-locked area of atrial tissue. Next, an ADF shock is introduced, if still needed, to achieve atrial defibrillation. ADFT energy requirements have been shown to be dramatically reduced on account of using pacing rates set proportionally to the sensed local atrial fibrillation cycle lengths such that large areas of atrial tissues are phase-locked, and consequently atrial defibrillation can be effected in the patient with greatly reduced energy requirements for ADFTs.

Abstract: The present invention relates to an improved method of impregnating electrolytic capacitor stacks or wound rolls with a polymer electrolyte such as a hydroxyethylmethacrylate (HEMA) or hydroxyethylacrylate (HEA) based polymer electrolyte, to render them suitable for use in electrolytic capacitors, and to such electrolytic capacitors. The initiator to promote the polymerization of this electrolyte is deposited on the foil or in the stack or wound roll prior to impregnation of the polymer electrolyte, allowing the electrolyte to be warmed to a temperature suitable for easy impregnation into the anode and cathode foil and paper.

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: A method for delivering cardiac therapy, particularly defibrillation therapy, using an implantable cardioverter-defibrillator (ICD) or other cardiac therapy device. The method can be used either alone or in conjunction with any other suitable defibrillation (or other cardiac) therapy regimen. If used in conjunction with a conventional or other suitable defibrillation therapy regimen, the method can be considered to precondition the heart in advance of delivery of the defibrillation shock(s), in order to reduce the defibrillation threshold (DFT), and thus reduce the overall energy required for delivery of effective defibrillation therapy. In either case, in accordance with the method, the voltage gradients (VGs) across a plurality of different regions of the heart are sensed, e.g., using an endocardial sensor array (ESA), and a respective plurality of electrograms (EGMs) are produced in respective EGM channels. The excitable gaps (i.e.

Abstract: A method of manufacturing a capacitor by highly etching a foil sheet, and at selected relief portions of the sheet, reducing the surface area coefficient. An anode sheet is cut from the foil sheet and assembled with other capacitor components. The surface area coefficient may be reduced by coining or mechanically compressing at the selected relief portions, and an oxide layer may be formed on the sheet after coining.

Abstract: A surface active, viscosity modifying agent is used to promote additional tunnel initiation during the etching of high purity cubicity anode foil, preferably aluminum anode foil, to render it suitable for use in electrolytic capacitors. The anode foil is etched in the electrolyte bath composition by passing a charge rough the bath, resulting in an anode foil having a higher capacitance than foils etched using known methods or etching compositions. The etched anode foil is suitable for use in an electrolytic capacitor.

Abstract: This present invention is directed to a method of etching anodic foil for electrolytic capacitors and provides a method of electrolytically growing a porous oxide mask on a surface of a high purity etchable strip of anodic foil for forming etch tunnels at strategic locations on the foil. Unetched high purity aluminum foil is placed in a prepared electrolyte doped with chloride. By passing current through the foil, a porous oxide mask is formed on the surface of the anode foil, with an optimized pore spacing. This oxide mask is then partially removed with a stripping agent in order to expose the underlying anode foil at the bottom of the mask pores to the etch solution. The mask is not removed completely, and the anode foil is exposed only at the pore sites. The foil can then be etched using a conventional etch solution. Etch pits and tunnels form only at the pore sites.

Abstract: An oxide dissolving acid dip is integrated into an anodic foil formation process. After a foil, either etched or un-etched, is hydrated in a bath of deionized water at an elevated temperature, the foil is then dipped in an organic acid mixture. Next, an oxide layer formation step is utilized to form a barrier oxide layer on a surface of the foil. Next, an oxide dissolving acid dip is utilized to selectively remove a diffuse hydrate layer formed in the formation process. The diffuse hydrate layer is responsible for the reduction of capacitance of the anodic foil. By the use of this oxide dissolving acid dip in conjunction with an organic acid dip, the foil exhibits reduced leakage current properties, while maintaining its capacitance. The treated foil can then be incorporated into a high voltage electrolytic capacitor suitable for use in an implantable cardioverter defibrillator.

Abstract: An electrolytic capacitor with an electrically conductive housing defining a chamber and defining a feed-through aperture providing communication between the interior and exterior of the housing. A number of conductive layers are positioned within the chamber. A feed-through conductor has a first end connected to the layers, an intermediate portion passing through the feed-through aperture, and an elongated external portion extending externally from the housing and terminating at a free end. An insulative sleeve has a first portion closely received within the feed-through aperture and closely receiving the intermediate portion of the feed-through member and has a second elongated portion extending externally from the housing and closely receiving at least a portion of the external portion of the conductor element, so that only a remaining portion of the conductor element is exposed, and is spaced apart from the housing by the length of the second elongated portion.

Abstract: Aluminum anode foil is etched using a process of treating the foil in an electrolyte bath composition comprising aluminum chloride hexahydrate, hydrochloric acid, sulfuric acid and perchloric acid or perchlorate. The anode foil is etched in the electrolyte bath composition by passing a direct current (DC) through the bath, resulting in an aluminum anode foil having a higher capacitance and/or metal strength than using known methods or etching compositions. The etched anode foil is suitable for use in an electrolytic capacitor.

Abstract: A system and method for providing improved defibrillation thresholds. In one embodiment of the invention, following the detection of fibrillation, a pacing pulse train is applied to a pacing electrode placed in the low gradient region of the left ventricular freewall to capture the tissue. In one embodiment, a pacing rate of about 80-95% of the VF cycle length is applied to achieve capture. Once capture of the tissue of the critical region is achieved, a high energy shock is delivered when the captured tissue is in the process of activation. The defibrillation shock is delivered at the end of the pacing train, with a coupling interval of either about 80-95% of the pacing rate (i.e., about 64-90% of the VF cycle length), or, alternatively, about 5-20% of the pacing rate (i.e., about 4-19% of the VF cycle length).