Abstract: A system and method for enhancing classification of tachycardias. The tachycardias are associated with a sequence of sensed cardiac complexes, each having a calculated morphology score. The method includes storing intervals corresponding to the sequence of complexes, analyzing the stored intervals, and excluding one or more of the morphology scores based upon the analyzed intervals.

Abstract: A system and method for applying atrial therapy to a human heart using a defibrillator includes detecting an atrial arrhythmia and delivering electrical energy to at least one atrium in response to a detected atrial arrhythmia. A first atrial activation is detected after delivering the electrical energy, occurrence of a detected first atrial activation defining a first moment. Finally, a first pacing pulse is delivered to a number of locations within the atria when the first atrial activation is detected. The first pacing pulse is delivered at a second moment substantially synchronous with the first moment.

Abstract: An implantable cardioverter-defibrillator has a housing containing cardioverter-defibrillator circuitry and a capacitor assembly. The capacitor assembly includes at least two flat capacitors each having opposed major surfaces. Each capacitor has an anode contact at one major surface, and a cathode contact at the opposite major surface. The anode contact of one of the capacitors contacts the cathode contact of the other. Each capacitor contact may be a thin metal plate covering the entire surface of the capacitor, with each plate connected to corresponding interleaved cathode or anode flat sheets between the plates. A non-conductive perimeter may enclose the sheets and connect the plates to each other.

Abstract: Methods and systems for performing pacing interval optimization are provided. One or more optimum pacing interval is determined for each of a plurality of different ranges of heart rate, different levels of autonomic tone, different body temperature ranges, or combinations thereof. The information (e.g., measures of hemodynamic response) collected to perform pacing interval optimization can be collected and stored in a table over disjoint periods of time. Such measures of hemodynamic performance are preferably relative measures, but can alternatively be absolute measures.

Abstract: A voltage step-down circuit reduces the amount of power drawn from the battery of an implantable cardiac stimulation device (ICD) to supply an integrated circuit (IC) within the ICD. The ICD battery supply voltage is reduced to a level that maintains proper operation of the IC. The reduced battery supply voltage is also regulated such that the IC is supplied with a constant voltage source. The IC consumes less power when supplied by the reduced battery supply voltage than when supplied directly by the battery supply voltage. The present invention promotes ICD battery longevity and reduces the need for frequent ICD battery replacements.

Abstract: An implantable medical device having a sealed housing forming a chamber containing rhythm management circuitry. The housing has an exterior defining a recess in which a header is received. The header has a number of lead bores, and includes an electrical contact within each bore, with each contact connected to the circuitry in the housing. The housing recess encompassing a major portion of the header, which may be positioned away from the corners of the housing, and which may be formed to avoid protruding from the housing. The recess may enclose at least three orthogonal sides of the header, and may include opposed parallel side capturing the header.

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: An apparatus for extracting activity information and position information from a composite signal generated by a motion sensor includes an analog to digital converter for converting the composite signal from analog to digital format. A wide-band low pass filter having a frequency response of about zero hertz to about ten hertz and a narrow low pass filter having a frequency response of about zero hertz to about 0.5 hertz filter the digitized composite signal. An adder subtracts the output of the narrow-band low pass filter from the output of the wide-band low pass filter. The resulting difference represents information regarding the activity level of the motion sensor, and the output of the narrow-band low pass filter represents information regarding the position of the sensor.

Abstract: A device, such as an implantable cardiac device, and methods for determining heart rate recovery of a patient after exercise. Specifically, the method includes identifying a first heart rate indicative of exercise, a second heart rate indicative of a slow-down in exercise, and using the first and second heart rates to determine a measure of heart rate recovery. The first heart rate may be identified when a heart rate measurement and/or an activity level exceeds a predetermined threshold. The second heart rate may be identified based when a heart rate measurement and/or the activity level falls below a predetermined threshold. The device includes hardware and/or software for performing the described methods.

Abstract: A device, such as an implantable cardiac device, and methods for determining exercise diagnostic parameters of a patient are disclosed. Specifically, a maximum observed heart rate of a patient during exercise can be identified when an activity level and a heart rate measurement of the patient exceed predetermined thresholds. Included are methods for filtering out premature heartbeats or noise from the maximum heart rate determination. Methods of determining other exercise parameters, such as workload are also disclosed. The device includes hardware and/or software for performing the described methods.

Abstract: An implantable cardioverter-defibrillator has a housing containing cardioverter-defibrillator circuitry and a capacitor assembly. The capacitor assembly includes at least two flat capacitors each having opposed major surfaces. Each capacitor has an anode contact at one major surface, and a cathode contact at the opposite major surface. The anode contact of one of the capacitors contacts the cathode contact of the other. Each capacitor contact may be a thin metal plate covering the entire surface of the capacitor, with each plate connected to corresponding interleaved cathode or anode flat sheets between the plates. A non-conductive perimeter may enclose the sheets and connect the plates to each other.

Abstract: Methods and devices are provided for reducing motion artifacts when monitoring volume changes in blood vessels. Light having a first wavelength and light having a second wavelength are transmitted through a human appendage, toward the epidermis of a patient, or through tissue within the body of a patient. A portion of the light having the first wavelength and a portion of the light having the second wavelength is received. A first signal is produced based on the received portion of light having the first wavelength. A second signal is produced based on the received portion of light having the second wavelength. One of the first and second signals is subtracted from the other to produce a plethysmography signal that is representative of volume changes in blood vessels of patient tissue.

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: 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: A method for monitoring the progression of the hemodynamic status of a patient by tracking autonomic tone. For example, the method may be applied to patients suffering from heart failure, diabetic neuropathy, cardiac ischemia, sleep apnea and hypertension. An implantable or other ambulatory monitor senses a pulse amplitude signal such as a vascular plethysmography signal. Variations of the signal amplitude on a scale greater than the heartbeat to heartbeat scale are indicative of variations in autonomic tone. A significant reduction in pulse amplitude and pulse amplitude variability are indicative of a heart failure exacerbation or other disease state change. This information may be used to warn the patient or healthcare providers of changes in the patient's condition warranting attention.

Abstract: Pacing pulse power efficiency is increased in an implantable cardiac stimulation device. The invention includes a cardiac function sensor for sensing cardiac functions. A controller is coupled to the sensor for determining a required cardiac pacing pulse voltage level. A determining means is coupled to the controller for determining a desired battery voltage multiplication factor as a function of the required pacing pulse voltage level. A setting means is coupled to the determining means for setting a battery voltage multiplier to multiply the battery voltage to a level as close as possible to the required pacing pulse voltage level.

Abstract: An apparatus and method for pacing and sensing the right side as well as the left side of the heart (bi-ventricular pacing and sensing). The bi-ventricular pacing and sensing is accomplished by introducing an additional dedicated pacing and sensing path for the left ventricle of the heart. Two additional terminals are added to the pacing and sensing path for the left ventricle to enable pacing and sensing in the left ventricle of the heart. In addition, switches are added to the pacing path for the left ventricle of the heart. The switches are controlled by a programmable controller and allow the selection of the desired ventricle(s) in which pacing is to occur.

Abstract: Improved methods and devices perform anti-tachycardia pacing (ATP) to convert a ventricular tachycardia (VT) to normal sinus rhythm. In one embodiment of the invention bi-ventricular (BV) ATP is employed. In this embodiment the right ventricle and left ventricle of a patient's heart are independently paced based on signals sensed in each chamber.

Abstract: A method of producing electrodes for electrolytic capacitors by etching metal foil in a low pH etching electrolyte is disclosed. The low pH electrolyte is an aqueous solution, which comprises hydrochloric acid, glycerol, sodium perchlorate or perchloric acid, sodium persulfate and titanium (111) chloride. Anode foils etched according to the method of the invention maintain high capacitance gains, electrical porosity and strength. The electrical porosity of the etched foils is sufficiently high such that the overall Equivalent Series Resistance (ESR) is not increased in multilayer anodes configurations. Also described is a low pH electrolyte bath composition. Anode foils etched according to the present invention and electrolytic capacitors incorporating the etched anode foils are also disclosed.

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.