Abstract: A high voltage charger operates in a three-phase cycle. In a first phase, the high voltage charger operates at a fixed frequency. In a second phase, the high voltage charger operates at a variable frequency designed to draw a substantially constant average current from a power source. In the third phase, the high voltage charger returns to fixed frequency operation. The variable frequency is the reciprocal of the sum of an on-time and an off-time of the switch. In one embodiment, the on-time is provided by the time required for the switch to reach a predetermined maximum and the off-time is provided by the time over which a magnetic field in a transformer collapses.

Abstract: A lead sealing device that resides within the connector cavity of a pacemaker or defibrillator intended to prevent fluid intrusion by automatically sealing the lead lumen when the lead connector is inserted. The sealing mechanism may be in the form of a silicone disk located at the base of the space defined by the connector cavity in which the lead is inserted to make electrical and physical contact. It may be fixedly located at the bottom of the connector cavity, or may be a movable plug located within the connector cavity at a location other than the bottom of the cavity, such as adjacent to the connector block. In that case, the pin will make contact with the movable plug immediately after passing through the connector block, and will remain in contact with and seal the lead lumen while the pin and plug are further advanced to bring the pin into its final location to make electrical contact with the connector contact.

Abstract: An electrophysiology diagnostic device generating a high voltage (HV) pulse of a predetermined shape, which device is electrically connected to a patient's heart, i.e., a load resistance and which device includes a microprocessor and a load resistance measuring device, consists of a rapid response voltage threshold determination (RRVTD) circuit and a variable capacitance emulation (VCE) circuit. The RRVTD circuit receives an actual signal corresponding to the HV pulse waveform, compares the actual signal with a desired signal and produces an error signal when the actual signal deviates from the desired signal by a predetermined threshold value. The VCE circuit, which is capable of emulating a selected capacitance C, includes a fixed capacitor C.sub.0, and first and second branch circuits including respective resistors R.sub.1 and R.sub.2 and corresponding switching elements, connected in parallel with the load resistance R.sub.L.

Abstract: An implantable lead for use with an implantable pacemaker/cardioverter/defibrillator. Since irradiation from a radioisotope source is capable of inhibiting the growth of hyperproliferating cells as compared with normal cells, a radioisotope material which is incorporated into the lead can be used to decrease the rate of fibrotic growth. The radioisotope may be located inside the lead, alloyed into the metal from which the lead electrode or conductor is made, molded into rubber portions of the lead, or coated onto the conductor or electrode's surface. Beta emitting radioisotopes would be best suited as a radioactive material because of their comparatively short range of action within human tissue.

Abstract: A method for characterizing the degree of similarity between phase space representations of trajectories of different dynamical systems. This method provides a computationally efficient technique for comparing different dynamical systems, or different dynamics exhibited by the same system. A first trajectory is designated as a template against which other trajectories are compared. A test trajectory is characterized by providing a measure based on determining the smallest distance between each point of the test trajectory to the template and then determining the largest of these smallest distances. The similarity of the two trajectories is quantified by establishing a lattice or grid for the phase space. For each lattice point, the distance, as given by a metric defined for the space, is calculated to the nearest point of the template trajectory. The minimum distance is retained and associated in a memory for each lattice point.

Abstract: A method and apparatus for performing electrophysiologic testing on a patient's heart using an implantable pulse generator system. The system includes an implantable pulse generator such as an implantable cardioverter-defibrillator having high voltage capacitors for storing electrical energy to defibrillate the patient's heart, a means for inducing a cardiac arrhythmia, an electrode system for discharging the stored energy into the patient's heart, and an external programmer for communication with and command of the implantable pulse generator. The method comprises the steps of charging the capacitors to a selected energy level upon command from the external programmer, inducing fibrillation in the patient's heart following the charging step, and discharging the capacitors through the electrodes into the patient's heart to defibrillate the patient's heart. The method and system provides flexibility in electrophysiologic testing by allowing the physician to control the time of delivery of high voltage therapy.

Abstract: An implantable suture sleeve for use with an implantable lead with a pacemaker/cardioverter/defibrillator lead. Since irradiation from a radioisotope source is capable of inhibiting the growth of hyperproliferating cells as compared with normal cells, a radioisotope material which is incorporated into the lead can be used to decrease the rate of fibrotic growth. The radioisotope may be located inside the suture sleeve, alloyed into or coated onto the metal from which a wire or coil within the suture sleeve is made, or molded into the rubber of the suture sleeve. Beta emitting radioisotopes having a half-life between 1 and 100 days would be best suited as the radioactive material due to their comparatively short range of action within human tissue, and because of their comparatively short half-life.

Abstract: A segmented axial gradient array lens is provided. In one embodiment, the segmented array lens includes two sheets of optical material which mate at opposing faces which have a series of corresponding parallel grooves and ridges. At least one of the sheets has an axial gradient index of refraction profile. This provides the functionality of a series of parallel cylindrical lenses. The array lenses may include one or more additional intermediate sheets which may have a homogeneous or axial gradient index. With the first and last sheets having an axial gradient index of refraction, and the grooves forming the first and last interfaces between the sheets being rotated 90 degrees relative to each other, a two dimensional array of point foci can be provided. An array of cones and conical indentations can be used at the interfaces to provide the functionality of an array of spherical lenses. An array lens of the invention can be used to provide an optical multiplexer.

Abstract: A surface mount component which can be mounted to a surface of a printed circuit board having a plurality of bonding pads connected to circuitry provided on the printed circuit board, which includes a puck having first and second wiring patterns, and a plurality of electrical connectors, a first set of electrical connectors being connected to the first wiring pattern, and a second set of the electrical connectors connected to the second wiring pattern. During the process of manufacturing a product which incorporates the printed circuit board, a production line worker can mount the puck to the surface of the printed circuit board in a selected one of a plurality of different possible positions, with at least selected ones of the first and second sets of electrical connectors being connected to respective ones of said bonding pads, to thereby achieve a selected one of a plurality of different selectable circuit configurations.

Abstract: An electrophysiology diagnostic device generating a high voltage (HV) pulse of a predetermined shape, which device is electrically connected to a patient's heart, i.e., a load resistance and which device includes a microprocessor and a load resistance measuring device, includes a variable capacitance emulation (VCE) circuit. The VCE circuit, which is capable of emulating a selected capacitance C, includes a fixed capacitor C.sub.0, and first and second branch circuits including respective resistors R.sub.1 and R.sub.2 and corresponding switching elements, connected in parallel with the load resistance R.sub.L. According to one aspect of the VCE circuit, the selected capacitance C satisfies the expression C=?(R.sub.L .parallel.R.sub.eff)*C.sub.0 !/R.sub.L, where R.sub.eff is an effective resistance value produced by pulse width modulation control of at least one of the resistors R.sub.1 and R.sub.2 using corresponding switch elements.

Abstract: A lead system for use with an implantable cardioverter/defibrillator is disclosed. The lead system includes a fixation hook positioned approximately half-way between the distal tip of the lead and the tricuspid valve. The distal tip of the lead is positioned at the apex of the right ventricle and may or may not be secured there by a second fixation means such as a screw tip or tines. The fixation hook allows the defibrillation electrode to be accurately positioned by the patient's surgeon and maintained in contact with the septum wall of the patient's heart. By providing such intimate contact between the defibrillation electrode and the septum wall, defibrillation thresholds are reduced.

Abstract: An implantable medical apparatus operable in conjunction with an attachable lead, and having a housing containing an electronic component, with a header connected to the housing and defining a cavity. A connector element is positioned within the cavity and is operably connected to the electronic component. A lens is connected to the header, such that the connector element may be viewed through the lens to facilitate confirmation of proper connection of a lead to the connector. The header may be transparent, and the lens either formed as part of the header, or detachable therefrom.

Abstract: A microstrip EMI shunt for an implantable medical device (e.g., an ICD) which includes a microstrip transmission line secured to an interior surface of a housing of the device, the microstrip transmission line having a first end secured to a connector wire which is electrically coupled to internal electronics of the device, and a second end which is open-circuited. The microstrip transmission line has a length n.lambda./4, where .lambda. is the wavelength of EMI (in the microstrip medium) having a selected frequency f which is desired to be shunted, and n is an odd integer .gtoreq.1. In operation, EMI of the frequency f is shunted via the microstrip transmission line prior to reaching the internal electronics of the device. Additional microstrip transmission lines having appropriately chosen lengths to shunt EMI of different frequencies can also be provided.

Abstract: A lead system for use with an implantable pacemaker/cardioverter/defibrillator. The lead system includes a securable pace/sense electrode positioned between the distal tip of the lead and the tricuspid valve. The distal tip of the lead is positioned at the apex of the right ventricle and may or may not be secured there by a second fixation means such as a screw tip or tines. The securable pace/sense electrode allows the defibrillation electrode to be accurately positioned by the patient's surgeon and maintained in intimate contact with the septum wall of the patient's heart, thereby reducing defibrillation thresholds; it provides a sense signal from the region of the His bundle or AV node, which can be used with other electrodes to distinguish between various arrhythmias; and it provides more physiologic pacing leading to greater cardiac output.

Abstract: A header adapter which is a separately molded part and which is designed to be secured to receiving portions of the header and pulse generator case of an implantable cardiac stimulation device, such as a pacemaker or implantable cardioverter-defibrillator, in order to provide a different lead connector port configuration than that provided by the header of the device. The header adapter has a plurality of adapter lead connector ports and a plurality of lead connectors affixed to a rear portion (mounting side) thereof. The lead connectors extend outwardly from the rear portion of the header adapter, and are insertable into corresponding lead connector ports of the header of the implantable cardiac stimulation device to which the header adapter is to be secured.

Abstract: The present invention is directed toward providing a composite lead body design for pacing and defibrillation leads. This lead body design improves the lead crush resistance in the lead segment that is implanted in the patient's clavicular region, while maintaining good fatigue resistance in the lead segment implanted in the heart. The clavicular segment has a generally flat profile. By flattening the clavicular segment proximal to the venous entry site, the lead will have a lower profile. Also, by substantially co-aligning the conductors within the clavicular segment, the crush resistance of the lead is significantly improved.

Abstract: An implantable cardiac therapy device collects patient ECG and device status information, including cardiac event interval information, why therapy was or was not applied, and patient response to therapy, in connection with an arrhythmic episode and correlates such information in a data frame that may be stored for later telemetric transmission to an external instrument or that may be transmitted in real time to the external instrument. The data frame is decoded and parsed by the external instrument for presentation to an attending physician in a time correlated format.

Abstract: A lead sealing device that resides within the connector cavity of a pacemaker or defibrillator intended to prevent fluid intrusion by automatically sealing the lead lumen when the lead connector is inserted. The sealing mechanism may be in the form of a silicone disk located at the base of the space defined by the connector cavity in which the lead is inserted to make electrical and physical contact. It may be fixedly located at the bottom of the connector cavity, or may be a movable plug located within the connector cavity at a location other than the bottom of the cavity, such as adjacent to the connector block. In that case, the pin will make contact with the movable plug immediately after passing through the connector block, and will remain in contact with and seal the lead lumen while the pin and plug are further advanced to bring the pin into its final location to make electrical contact with the connector contact.

Abstract: A defibrillator having a housing for enclosing and containing defibrillation pulse generator circuitry, particularly adapted to allow for ease of manufacture and use. At least one surface of the housing is electrically conductive and may be connected to the defibrillation pulse generator circuitry for delivering defibrillating energy to the heart. The defibrillator is provided with two case-activating setscrew blocks isolated from two contacts. By tightening the first setscrew onto its contact, the can is activated and is positive for defibrillation. By tightening the second setscrew instead, the can is activated and is negative for defibrillation. Tightening neither setscrew maintains the inactive status of the can. By using this system, various electrode configurations can be used as required to provide the optimum system for a given patient. The defibrillator generator housing is preferably implanted in the left pectoral region proximate the heart with the conductive surface facing the heart.

Abstract: A defibrillation insulating device prevents current from directly shunting through the blood pool from the right ventricular defibrillation electrode to a superior vena cava electrode and vice versa. This forces current to flow through the heart muscle, thus increasing the current density throughout the heart, to depolarize the majority of the cardiac tissue with a minimum of energy.