Abstract: An implantable anti-tachyarrhythmia device which delivers anti-tachyarrhythmia therapies to a patient's heart in response to detection of tachyarrhythmias. The device defines first criteria indicating the presence of atrial tachycardia and second criteria indicating the presence of atrial fibrillation, and compares the time elapsed since the either the first or second criteria were initially met to a defined time duration. In response to the defined duration having passed and either of the first or second criteria being met, the device triggers delivery of an appropriate anti-tachyarrhythmia therapy. The timer is reset on detection of termination of atrial tachyarrhythmia, but not on failure of the first and second criteria to be met. The first and second criteria are defined such that they can not be concurrently met.

Abstract: A device for use in communication with an implantable medical device. The device is provided with a spatial diversity antenna array mounted to a housing and an RF transceiver operating at defined frequency, coupled to the antenna alray. The antenna array comprises two antennas spaced a fraction of the wavelength of the defined frequency from one another, each antenna including two antenna elements mounted to the housing and located oithogonal to one another. Selection of which of the antennas is employed is accomplished by an device controller, responsive to the quality of the signals received by the antennas.

Abstract: A shape memory device includes a shape memory alloy member configured to have at least a portion of the shape memory alloy member be selectively activated. A heating device is coupled to the member and configured to provide heat to a selected section of the member and activate at least a portion of the selected section.

Abstract: A device for use in communication with an implantable medical device. The device is provided with a spatial diversity antenna array mounted to the device housing and an operating at defined frequency, located within the device housing, coupled to the antenna array. The antenna array includes at least one antenna permanently mounted to the device housing and an antenna removably mounted to the device housing and locatable at a distance from the housing, coupled to the RF transceiver. A device controller selects which of the antennas in the antenna array is coupled to the transceiver responsive to the quality of signals received by the antennas.

Abstract: An implantable anti-tachycardia pacemaker having the capability of switching from a first pacing regimen to a second pacing regimen, without waiting to determine whether the first pacing regimen actually is successful in terminating the tachycardia. The device first delivers a short series of pacing pulses at the defined parameters of the first pacing regimen and then interrupts delivery of pacing pulses and measures the return cycle of the subsequent spontaneous depolarization. The device then resumes delivery of the first pacing regimen for a second, greater number of pacing pulses and again measures the return cycle. In the event that no increase in the return cycle occurs following the delivery of the longer series of pacing pulses, the device terminates the pacing regimen presently underway, and initiates the next scheduled therapy. In the event that an increase in the return cycle is detected, the device may simply deliver the programmed number of pacing pulses defined for the first pacing regimen.

Abstract: An introducer system for introducing a lead or catheter and a method of use. The introducer system includes an elongated introducer sheath which has a luer hub mounted to its proximal end through which a lead or catheter is introduced and a slitter for slitting the luer hub and the introducer sheath. The slittable luer hub takes the form of a conical or cylindrical member carrying a laterally extending tab adapted to engage internal threading on a female luer lock fitting and has a slittable portion angularly displaced from the tab. The slitter includes a blade, a handle carrying the blade, a mechanism for engaging the lead or catheter in the vicinity of the blade and a mechanism for engaging the lead or catheter proximal to the blade, configured such that the lead or catheter body when engaged by the slitter is angled proximal to the blade of the slitter.

Abstract: Endocardial implantable cardiac leads are disclosed for applying electrical stimulation to and/or sensing electrical activity of the heart at one or more distal electrode positioned at a cardiac implantation site within a cardiac vessel adjacent to and at a desired orientation to the left ventricle or atrium of the heart. The distal electrode(s) is supported by a tubular electrode support having a diameter large enough to bear against the blood vessel wall and a support lumen that allows blood to flow through it. A retention stent extends proximally from a distal stent end fixed to the tubular electrode support to a proximal stent end. After advancement to the cardiac implantation site employing a lead delivery mechanism, the retention stent is expandable from a collapsed stent state in which the outer diameter of the retention stent is less than the inner diameter of the vessel to an expanded stent state.

Abstract: A deflectable stylet or guidewire formed of an elongated tube having a coil mounted to its distal end and a movable tension or push wire mounted within the coil and the tube, mechanically coupled to the distal end of the coil. A backbone is located within the coil, mechanically coupled to the proximal and distal ends of the coil and extending along one side of the coil. The backbone may be provided with projections extending laterally between adjacent turns of the coil and may have a generally arcuate cross section having a width greater than its arc height. In some embodiments the backbone may be formed from a tube having a slot extending longitudinally along one side thereof. In some embodiments the backbone may be attached to the coil at points between the proximal and distal ends of the coil.

Abstract: A cardiac pacing lead for use in the coronary sinus and coronary veins. The lead is provided with a lead body configured to exhibit a curved configuration along a distal portion thereof, induced to maintain a portion of the curved configuration solely by means of a portion of a polyurethane lead body formed to display the curved configuration and wherein the lead conductor is freely mounted within the segment. The curved configuration includes first and second arcuate segments together providing a single-plane curvature of approximately 180 degrees, separated by a generally straight segment, the first segment having a greater length and greater arc of curvature than the second segment.

Abstract: A method or apparatus for conserving power in an implantable medical device (IMD) of the type having at least one IC powered by a battery wherein, in each such IC, a voltage dependent oscillator for providing oscillator output signals at an oscillation frequency dependent upon applied supply voltage to the IC is incorporated into the IC. The voltage dependent oscillator oscillates at a frequency that is characteristic of the switching speed of all logic circuitry on the IC die that can be attained with the applied supply voltage. The applied supply voltage is regulated so that the oscillation frequency is maintained at no less than a target or desired oscillation frequency or within a desired oscillation frequency range. The power supply voltage that is applied to the IC is based directly on the performance of all logic circuitry of the IC.

Abstract: An implantable antiarrhythmia device which detects and classifies arrhythmias of the human heart, and delivers appropriate therapy. The device employs a method of arrhythmia classification based on a set of prioritized rules, each of the rules defining a plurality of criteria based upon characteristics of sensed depolarizations of heart tissue, each rule being met when the criteria associated with the rule are met. Some rules, when met, trigger delivery of antiarrhythmia therapy. Other rules, when met, inhibit delivery of antiarrhythmia therapy. The rules may be met simultaneously, and if so, the highest priority rule governs the behavior of the device.

Abstract: An arrangement for transvenously introducing and fixing a cardiac electrode at a cardiac implantation site. The arrangement includes a pusher having an elongated body of flexible material, which may be coupled with a cardiac lead adjacent the distal end of the cardiac lead and may be employed to advance the cardiac lead transvenously. The pusher is provided with an engagement mechanism which engages the distal end of the cardiac lead while the lead extends proximally along side the exterior surface of the pusher and which engages the distal end of the lead body when the pusher body is advanced distally and disengages from the cardiac lead body when the pusher is withdrawn proximally. The pusher body has sufficient column strength to be advanced through a patient's venous system to a desired implantation site within the heart.

Abstract: A distributed activation system for a unitary sheet of electrically conductive or insulative shape memory alloy having a sufficiently small section to limit the lateral flow of heat including at least one heating element disposed on the shape memory alloy sheet for locally heating an adjacent portion of the sheet such that the adjacent portion assumes a predetermined shape when activated to its threshold temperature. The activation system may be configured for shape memory alloy apparatus and related methods in combination with a control system for selectively activating discrete shape memory alloy portions with various combinations of at least one heating element that receive an adjustable current such that the resultant local heating causes the sheet to assume a desired overall shape. Methods of forming and selectively activating two-dimensional sheets of electrically conducive and insulative shape memory alloy are further provided.

Abstract: An implantable anti-arrhythmia system which includes a spinal cord stimulator and an implantable heart rhythm monitor, coupled to control the spinal cord stimulator. The implantable heart monitor is adapted to detect the occurrence of tachyarrhythmias or of precursors thereto and in response, trigger the operation of the spinal cord stimulator in order to prevent occurrences of tachyarrhythmias and/or as a stand-alone therapy for termination of tachyarrhythmias and/or to reduce the level of aggressiveness required of an additional therapy such as antitachycardia pacing, cardioversion or defibrillation. The device in most embodiments is expected to include a mechanism for delivering an electrical anti-tachyarrhythmia therapy such as pacing, cardioversion or defibrillation in response to detection of a tachyarrhythmia. However, in some embodiments the spinal cord stimulator may be the only electrical stimulator included in the system.

Abstract: A cyclic redundancy code (CRC) and optionally a syndrome value calculation of one or more implantable medical device (IMD) data block is conducted by block mover/reader hardware of the IMD when the data block(s) are moved and/or read. In the block read operation, each data byte or word in the block mover data register is read in a first clock cycle. In the block move operation, each data byte is read in the first clock cycle in this way and then moved to a destination register in a second clock cycle. The data CRC and optionally the syndrome value accumulate in the CRC and syndrome registers as all data bytes of the data block(s) are read in the first clock cycle.

Abstract: An implantable lead which has an increased resistance to fracture and has the capability of continued function after fracture of a conductor. The lead is provided with a coiled conductor which may be monofilar or multifilar and which extends along the length of the lead, running from an electrical connector at the proximal end of the lead to an electrode at or near the distal end of the lead. In addition, the lead is provided with a stranded conductor which is electrically coupled to the coiled conductor at point along the lead body located proximal to the point of expected breakage of the coiled conductor and at a point along the lead body located distal to the point of expected breakage. The proximal and distal ends of the stranded conductor in some embodiments are also mechanically coupled to the coiled conductor.

Abstract: Two mechanisms work together to adjust two variables independently so that the gain of an input amplifier used to find physiologic signals in an implantable medical device can be automatically adjusted to enhance the signal to noise ratio of the electrical input to said amplifier. The first determines whether there has been too long a time between senses found in the body's electrical input to the amplifier and if true, and no other conditions override that consideration, it adjusts the value of a long term average parameter which is used as a referent parameter to adjust the actual parameter that is used as the referent for making either a threshold level adjustment or gain change, depending on the structure of the particular design's circuitry and/or software. One set of adjustments to the gain referent parameter depends on the relative size of the long term average parameter and the gain referent parameter.

Abstract: A lead which is provided with a lead body and a connector assembly which are flexible and resistant to fatigue caused by flexing of the lead relative to an associated implantable medical device to which the lead is coupled. The lead is provided with an elongated lead body with a connector assembly located at its proximal end and carrying at least two elongated conductors extending along the lead body to the connector assembly, arranges such that distal to a first point along the lead body the lead body is provided with at least two separate longitudinal lumens, each carrying at least one of the two conductors and proximal to the first point, the lead is provided with a tubular member, arranged such that the two conductors extend proximally from the first point wrapped helically around the tubular member. In a preferred embodiment, the lead carries at least three elongated conductors, and at least one of the conductors is wrapped helically around the tubular at a pitch greater than the diameter the conductors.

Abstract: An implantable medical device (IMD) includes a distributed core, step-up transformer that is arranged within a hermetically sealed housing in space that would otherwise not be occupied and in a way that minimizes the size and weight of the IMD. The IMD preferably comprises an implantable cardioverter-defibrillator (ICD) of the type having a battery power source, a capacitor bank for storing a charge from the battery, and electronic circuitry coupled to the battery power supply and the capacitor bank for charging the capacitor bank through a step-up transformer and for discharging the capacitor bank into or around a patient's heart. The step up transformer comprises a plurality of distributed core step-up transformer modules which are miniaturized sufficiently to fit within small spaces of the housing cavity. The plurality of distributed core, step-up transformer modules are amenable to being arranged to fit into spaces within the cavity of the IMD housing that are not otherwise occupied.

Abstract: An endocardial pacing and/or cardioversion/defibrillation lead having a plurality of electrodes and a mechanism for adjusting the exposed surface area of one or more electrode and/or the position and/or angular orientation of an electrode along a lead body. A fixed exposed, flexible, elongated commutator surface is provided extending along the lead body intermediate the proximal and distal lead body ends coupled by an electrical lead conductor extending to the proximal end of the lead body. A movable electrode assembly is provided that fits over and slides along the lead body, including the fixed commutator surface, that supports an exposed movable electrode on it. The movable electrode assembly includes at least one flexible, elongated, movable commutator surface within it that is electrically connected with the movable electrode.