Abstract: An implantable stimulation lead having an anti-inflammatory coating on the exposed surface area of the distal tip electrode. The coating is a semi-viscous or gelatinous material having the ability to absorb physiological fluids to provide electrical conductivity through the coating. The coating preferably has a matrix having an innate hypo-inflammatory property which can be combined with drugs and therapeutic agents to deliver the drugs and agents by co-dissolution or diffusion, or alternatively the matrix material can be used as a coating to keep the electrode surface electrochemically clean prior to and during implant.

Abstract: A pacing lead having a porous electrode of platinum-iridium with recessed areas or grooves formed into the surface. The grooves allow for acute electrode stabilization as a result of clot formation and endocardial tissue capture during insertion and immediate immobilization upon implant. At least one layer of a porous coating of 20-200 micron diameter spherical particles are deposited on the surface of the base electrode to obtain a porous macrostructure for promoting chronic tissue ingrowth. Additionally, a microstructure surface coating is applied to increase the active surface area and enhance electrical efficiency by lowering electrochemical polarization and increasing electrical capacitance.

Abstract: An implantable cardioverter-defibrillator (ICD) provides a tiered therapy designed to automatically terminate tachyarrhythmias using the least aggressive therapy possible while reducing the "time-to-therapy." The tiered therapy first applies a first tier of therapy (e.g., antitachycardia). If unsuccessful, the tiered therapy next applies a second tier of therapy (e.g., cardioversion pulse with a pulse of moderate energy). If unsuccessful, the tiered therapy finally applies a third tier of therapy (e.g., a high energy pulse). So that more aggressive (higher energy) tiered therapies may be applied as early as possible following the failure of a less aggressive (lower energy) therapy, the ICD begins charging one or more high voltage capacitors of the ICD in parallel with the application of the less aggressive therapy, and/or in parallel with the verification interval immediately following a prior therapy attempt during which the ICD attempts to verify the successful termination of the tachyarrhythmia.

Abstract: A sense amplifier adapted for use with a cardiac pacer or the like includes a constant gain filter, a window comparator circuit and a programmable threshold reference generator circuit. The reference generator circuit generates a programmable window (reference) voltage used by the window comparator circuit to determine whether an input signal, amplified by the constant gain filter, exceeds the window voltage. The reference generator circuit is based on a bipolar junction device having an adjustable emitter area through which a constant current flows. The emitter area is adjusted in response to a control signal. As the emitter area changes as controlled by the control signal, the voltage across the device changes. In a preferred embodiment, a parallel combination or network of switched bipolar junction devices is used to realize the adjustable emitter area.

Abstract: A method and system for monitoring the behavior of an implanted pacemaker counts (records) the number of times that a given internal event or state change of the pacemaker occurs, and also determines the rate at which each event or state change thus counted occurs. The event counts and their associated rate are stored (recorded) in appropriate memory circuits housed within the pacemaker device. At an appropriate time, the stored event count and rate data are downloaded to an external programming device. The external programming device processes the event count and rate data, and displays a distribution of the event count data as a function of its rate of occurrence, as well as other statistical information derived therefrom. The displayed information, and its associated statistical information, allows a baseline recording to be made that establishes the implanted pacemaker's behavior for a given patient under known conditions.

Abstract: An in-line, multipolar proximal connector assembly for an implantable stimulation lead is provided which incorporates at least one sensor. Advantageously, the present invention uses straight conductive rods, or wires, to electrically connect the proximal terminals to a multilumen lead body. The straight conductive rods enable the diameter of the lead assembly to remain small. Additional terminals can easily be added by simply decreasing the spacing between terminals and adding additional conductive rods. In one embodiment, insulating spacers are premolded to include protruding portions which interlock with the ring terminals. Recesses within the insulating spacers are dimensioned to self-position the ring terminals a precise distance from the pin terminal according to precise dimensions defined by the VS-1 (or other) standards. In another embodiment, the terminals are injection molded.

Abstract: A system and method for preventing atrial competition during sensor-driven operation of a dual-chamber pacemaker includes means for sensing atrial activity during an atrial refractory period. Atrial competition is avoided by either: (1) generating an atrial competition prevention (ACP) interval upon the detection of any atrial activity during the relative refractory portion of an atrial refractory period, and preventing any atrial stimulation pulses from being generated for the duration of such ACP interval; or (2) shortening the atrial refractory period in the event that the sensor-driven rate of the pacemaker begins to approach a rate that might place atrial stimulation pulses near the end of the unshortened atrial refractory period.

Abstract: A rate-responsive pacing system and method allows the inter-related sensor operating parameters associated with the physiological sensor of a rate-responsive pacemaker to be automatically and/or optimally set for a particular patient. The system includes both a pacemaker and an external programming device. The pacemaker includes appropriate memory circuits for recording a sensor indicated rate (SIR) signal in a histogram. The external programming device retrieves the SIR histogram data, as well as other data associated with the operation of the pacemaker, and selectively processes and displays such data in a prescribed manner. An Auto-Set sequence or routine, carried out by the external programming device, sets all of the rate-responsive operating parameters to a known initial value and places the pacemaker in a passive mode. In the passive mode the SIR signal does not control the pacing rate. The Auto-Set routine then displays instructions for the physician that cause diagnostic data to be collected.

Abstract: A ribbon conductor set and related method of production and installation are provided for electrically interconnecting components in an implantable medical device, such as a heart pacemaker unit or the like. The ribbon conductor set is formed by die cutting and/or stamping a thin plate of conductive material to define a plurality of conductor ribbons supported from a frame. The ribbon set and supporting frame are shaped for seated placement into a fixture to orient the conductor ribbons in predetermined array to extend between electrical components on the fixture, such as between connector blocks and feedthrough terminals of a heart pacemaker unit. The fixture thus supports the conductor ribbons for facilitated connection to the electrical components, such as by welding, after which the resultant subassembly may be further processed as by encapsulation within a cast epoxy head or the like.

Abstract: A physiological sensor forms an integral part of an implantable stimulation/sensing lead used with a medical device, such as a pacemaker. The stimulation/sensing lead includes a tip electrode to which a distal end of a first conductor is connected. The sensor is inserted in series with respective portions of a second conductor. A distal end of the second conductor/sensor is connected to the tip electrode. Operation of the stimulation/sensing lead occurs unipolarly through the first conductor only, with a signal return path being provided through the tip electrode and conductive body fluids. The sensor does not form part of the electrical circuit to the tip electrode, and there are no electrical connections or breaks in the insulation along the entire length of the first conductor.

Abstract: A system and method for preventing atrial competition during sensor-driven operation of a dual-chamber pacemaker includes means for sensing atrial activity during an atrial refractory period. Atrial competition is avoided by either: (1) generating an atrial competition prevention (ACP) interval upon the detection of any atrial activity during the relative refractory portion of an atrial refractory period, and preventing any atrial stimulation pulses from being generated for the duration of such ACP interval; or (2) shortening the atrial refractory period in the event that the sensor-driven rate of the pacemaker begins to approach a rate that might place atrial stimulation pulses near the end of the unshortened atrial refractory period.

Abstract: The present invention includes a body implantable lead having a multi-polar proximal connector, at least a first conductor coupled to at least one stimulating electrode, a sensor for sensing at least one physiologic parameter of the body, and a second and a third conductor coupled to the sensor. The sensor is hermetically sealed in a D-shaped housing. Sensor components are mounted onto a microelectronic substrate which is advantageously placed on an inner flat portion of the D-shaped housing. End caps having glass frit sealing rings are used to seal the ends of the shell. A hermetic seal is easily achieved by heating the glass frit such that the glass frit reflows between the end caps and the shell. Advantageously, the sensor terminals are sized to fit snugly within a narrow bore of the end cap which is then welded closed. The D-shaped sensor is placed on a carrier having at least two lumens.

Abstract: A telemetry system which will transmit data at a relatively high rate while retaining a high degree of accuracy is disclosed which utilizes a servo feedback loop in conjunction with a conventional reflected impedance receiving front end parallel LC circuit, an AM demodulator, and an oscillator to drive the LC circuit at a desired frequency. The feedback loop operates to keep the voltage across the LC circuit constant over time, and does not affect short term variations in the voltage across the LC circuit which are caused by the variations in the reflected impedance. While frequency response of the system without the loop declines from a maximum value at zero frequency, the frequency response of the system of the present invention with the loop is shifted which permits data transmission at a substantially higher rate.

Abstract: A body implantable lead including a sheath, an electrode sleeve secured at a distal end of the sheath, a rotor body positioned within the sleeve, a fixing helix secured to a distal end of the rotor body, a torsion spring secured to a proximal end of the rotor body, and a rotation guide formed between the electrode sleeve and the rotor body which includes a helical groove formed on either the rotor body or the electrode sleeve and at least one guide pin formed on the electrode sleeve or the rotor body, respectively.

Abstract: A suture sleeve assembly for gripping and anchoring the lead body of an implantable medical device, such as a cardiac pacemaker, includes a tubular member adapted to receive the lead body. Disposed about the tubular member is a collar movable longitudinally along the tubular member from a first, open position to a second position in which the collar compresses a portion of the tubular member into gripping engagement with the outer surface of the lead body. The collar is fabricated of a material that is stiffer than that from which the tubular member is fabricated.

Abstract: An implantable pacemaker provides three types of hysteresis for use in dual chamber and/or atrial tracking modes, such as VDI, VDD, DDI, DDD, VDIR, VDDR, DDIR or DDDR. The pacemaker defines a basic atrial escape interval (AEI) that defines the maximum time between a ventricular event and a subsequent atrial event, as well as an AV delay (AVD) that defines the maximum time between an atrial event and the next ventricular event. The sum of AEI plus AVD thus sets the rate at which stimulation pulses are generated in the absence of sensed natural cardiac activity. A first type of hysteresis, atrial escape rate hysteresis, causes the AEI to be extended upon sensing natural atrial beats (P-waves). The increased AEI remains in force so long as natural P-waves continue to be sensed during the AEI. Should a P-wave not be sensed during the AEI, a stimulation pulse is generated and the AEI reverts to its initial value.

Abstract: A ribbon conductor set and related method of production and installation are provided for electrically interconnecting components in an implantable medical device, such as a heart pacemaker unit or the like. The ribbon conductor set is formed by die cutting and/or stamping a thin plate of conductive material to define a plurality of conductor ribbons supported from a frame. The ribbon set and supporting frame are shaped for seated placement into a fixture to orient the conductor ribbons in predetermined array to extend between electrical components on the fixture, such as between connector blocks and feedthrough terminals of a heart pacemaker unit. The fixture thus supports the conductor ribbons for facilitated connection to the electrical components, such as by welding, after which the resultant subassembly may be further processed as by encapsulation within a cast epoxy head or the like.

Abstract: A system within an implantable stimulation device and a method for limiting the extent to which rate-responsiveness can be utilized during low battery periods. A battery threshold detector is utilized to detect when the battery is below a predetermined threshold. The implantable stimulation device then switches to base rate, but with a preset recovery time used to prevent rapid rate change. In an alternate embodiment, the device may then become rate-responsive again, but with a lower allowable maximum sensor rate being used.

Abstract: An atrial tracking dual-chamber pacemaker and method of use thereof for terminating a pacemaker-mediated tachycardia (PMT). The pacemaker includes means for determining whether the present heart rate exceeds a tachycardia reference rate, and if so, whether a PMT-indicating sequence of a tracked P-wave, including a retrograde P-wave followed by a V-pulse, occurs repetitiously for at least a predetermined number of cardiac cycles. The pacemaker includes means for measuring the interval between a P-wave and a V-pulse (PVI) and sets the PVI to 250 milliseconds when the measured value is less than 250 milliseconds. The pacemaker issues a PMT-terminating timed atrial pulse which is timed from a retrograde P-wave by a time equal to the PVI, plus a delay of about 25-100 milliseconds. In the event the atrial pulse fails to terminate the PMT, the process is repeated after a fixed number of cardiac cycles has occurred.

Abstract: An implant tool for use with an endocardial or other implantable lead having an extendable/retractable positive fixation tip includes a hollow cylindrical housing and a custom designed stylet. The cylindrical housing attaches to a proximal end of the implantable lead. The stylet is inserted through the implant tool and into a lumen of the lead. The presence of the stylet, made from a length of relatively stiff wire, helps guide the distal tip of the lead to a desired implant location. The cylindrical housing includes a body portion and an end portion. The end portion is rotatable relative to the body portion. The stylet includes a knob on its proximal end, and also includes a stub pin slightly forward of its proximal end. The stub pin is received within a slot along the side of the cylindrical housing. Two spaced-apart recesses along the length of the slot allow the stub pin to be respectively held therein.