Abstract: A bipolar electrode assembly for attachment to heart tissue for use with a pacemaker. The assembly has a hub member with a helical screw-in coil that acts as a first electrode and is used to attach the assembly to the heart tissue. The assembly further comprises a plurality of appendages that extend from the hub member and each have an electrode segment of electrically conductive material. The electrode segment of the appendages can act together as a single second electrode, or alternatively as a separate, independent electrodes, which may selectively be used for pacing or sensing. The electrode segments not only act as electrodes, but also allows heart tissue to grow directly into the conductive material to help secure the assembly to the heart. The assembly also has apertures and grooves for suture connection of the assembly to the heart. Methods of manufacturing the assembly and connecting the assembly to a heart are also described.

Abstract: A suture sleeve for securing the leads of a multiple lead implantable medical device includes lead gripping and anchoring portions. The sleeve has a pair of flexible side walls and longitudinally extending channels for receiving the leads. The side walls of at least the gripping portion have longitudinally extending, confronting, spaced apart edges and comprises two layers one of which is formed of a soft plastic such as silicone and the other of which is formed of a harder but flexible material such as polysulfone. Sutures placed and tied about the gripping portion compress the sleeve about the leads. Tightening of the sutures brings the confronting edges of the gripping portion of the sleeve into engagement thereby precluding further compression of the sleeve and preventing damage to the leads.

Abstract: A system and method for terminating a cardiac arrhythmia includes pacing means for stimulating the heart with at least one stimulation pulse during a narrow region of susceptibility (termination window) of the arrhythmia cycle. The location of the region of susceptibility is initially found by delivering the stimulation pulse(s) to the heart in accordance with a prescribed scan pattern. The scan pattern delivers the stimulation pulse(s) at a time during the cardiac cycle such that each successive stimulation pulse is presented to the heart at a slightly different time than was a prior stimulation pulse, thereby assuring that the region of susceptibility or termination window is eventually located. When the arrhythmia is successfully terminated, the location of the successful stimulation pulse within the prescribed scan pattern is stored.

Abstract: An arrangement is provided which enables the rapid and effective termination of electrical junctions for an implantable medical device such as a heart pacemaker, a defibrillator, or a cardioverter. A circuit board supporting electronic circuitry is receivable in a housing for the medical device and is provided with a plurality of female connectors on its outer surface. The female connectors are positioned and shaped to receive and guide mating male components into abutting engagement therewith. The mating male components include feedthrough wires which extend between the interior and the exterior of the housing and conductive pins from a battery used to power the medical device. When the male components and female connectors are in abutting engagement, they are fusion welded as by a laser or electron beam.

Abstract: An implantable rate-responsive pacemaker is disclosed wherein two or more sensors indicative of physiological demand are utilized in a fashion designed to realize the advantages of both sensors in a circuit producing a rate command signal which is used to operate the pacemaker at an optimum pacing rate which will closely match physiological need of the patient. A rate matrix is used to produce a specific selected rate which is unique to the particular combination of sensor inputs which are being measured at the particular time. In the preferred embodiment, a plurality of rate matrices are provided, with the appropriate rate matrix to be used being selected by a switch matrix which monitors the logic-processed and time-processed signals from the sensors, the outputs of the processing circuitry being used to select a cell in the switch matrix which corresponds to the exact set of conditions currently being encountered by the sensors.

Abstract: An implantable pacemaker having means for detecting and responding to a premature ventricular contraction (PVC), also includes circuit means for minimizing the likelihood of sensing a PVC when in fact a PVC has not occurred. The circuit means latches the occurrence of any atrial events sensed during the relative atrial refractory period of the pacemaker, whether such atrial events are noise or an early P-wave; and, in response to such latching, disables the PVC detection circuit until certain prescribed events occur, whereupon the PVC detection circuit is re-enabled. The prescribed events that re-enable the PVC detection circuit after it has been disabled include, e.g., the occurrence of a ventricular pulse or sensed R-wave. Further, in the event a PVC is detected and a desired PVC response is invoked, an additional circuit means automatically terminates the PVC response in the event the PVC response becomes stuck.

Abstract: An implantable rate-responsive pacemaker is disclosed wherein two or more sensors indicative of physiological demand are utilized in a fashion designed to realize the advantages of both sensors in a circuit producing a rate command signal which is used to operate the pacemaker at an optimum pacing rate which will closely match physiological need of the patient. A switch matrix monitors processed signals from the sensors to select a unique set of numerical coefficients indicated by the processed sensor signals. The selected set of numerical coefficients are used as weighting factors to weight the impact of each of the sensor signals in the calculation of a selected rate.

Abstract: A porous electrode for pacemakers is comprised of a plurality of platinum globules sintered together to form a porous mass of semi-hemispherical shape at the end of a platinum electrode stem. The globules, which are themselves made by sintering together spherically-shaped particles of approximately one micron diameter, provide the globules with an irregular outer surface of high total surface area. The globules have diameters within a critical range of 40-200 microns. The large total surface area of the globules improves the sensing function of an electrode configuration of given size and surface area, while the globule diameters of 40-200 microns have been found to beneficially accommodate tissue ingrowth within the electrode. In a preferred method of making the electrode, the platinum globules, which are formed by sintering together platinum particles of much smaller size, are mixed with organic solvent and organic binder to form a paste.

Abstract: A drive circuit for applying a supply voltage to a sending coil provides resonant coupling of the sending coil with the target coil regardless of changes in the inductance of the sending coil, as long as the resonant frequency of the sending coil is greater than the resonant frequency of the target coil. A controller provides variable delay intervals in the application of the supply voltage, thereby compensating for changes in the sending coil's inductance with the passage of time and proximity effects. The controller examines the reflected voltage induced in the sending coil by changing currents in the target coil to examine the degree of resonant coupling between the two coils and correct any mistuning.

Abstract: An implantable pacemaker provides a paced AV delay that is automatically adjusted to include patient variations in latency conduction, that is, the time interval between a stimulus to the heart and an evoked potential, time due to lead position and specific patient latency. An AV timer, designed to provide a programmed AV interval, starts its timing operation at the generation of an atrial pulse, and restarts the timing operation again at the occurrence of the evoked atrial potential. The evoked atrial potential is typically monitored from a ring electrode of a bipolar lead relative to the pacemaker can (case), although other monitoring configurations are also possible. The length of the AV intrval is programmed to a desired value using conventional programming techniques.

Abstract: A multi-contact connector system for electrically and mechanically connecting a lead for the delivery of electrical energy at a body site to an implantable source of the electrical energy includes a plug connector element carried at a proximal end of the lead which is received in a socket connector element carried on the source of electrical energy. The plug connector element is a radially expandable sleeve with a number of exteriorly exposed contacts respectively connected to conductors contained within the lead. Corresponding contacts are mounted in the interior of the socket connector element. The plug connector sleeve fits over a flexible expansion element contained in the socket connector element. The expansion element is operated by a toggle switch after the connector elements are engaged so as to radially expand.

Abstract: A rate-responsive pacing method and system senses the minimum blood oxygen saturation in the right atrium of a patient's heart and uses such minimum blood oxygen saturation as a control parameter for indicating the muscular activity of a patient. Because the oxygen content of the venous blood in the right atrium varies significantly as venous blood from all parts of the body is introduced therein, evidencing differing levels of oxygen demand throughout the patient's body, the minimum oxygen content of the venous blood provides an accurate and reliable measure of those portions of the patient's body experiencing the greatest oxygen demand, i.e., experiencing muscular activity. A rate-responsive pacing system includes means for sensing the minimum oxygen content in the right atrium over a prescribed time interval, and using such minimum oxygen content as a control parameter for adjusting the rate of the pacemaker.

Abstract: A multi-part molded pacemaker connector that meets the precise requirements imposed by the VS-1 standard, yet does not require complex or expensive machining of individual parts. Advantageously, the pacemaker connector is made from a plurality of individually molded parts, with each individual part being designed to readily allow the insertion of seals and other connector components, prior to joining the parts together. The connector includes three molded pieces: a body tip, a body ring, and an entrance connector which are adapted to be joined during assembly. The connector further includes a garter spring, and preferably, two annular sealing rings. A tip connector block is insert-molded into the body tip. A conductive tube, which forms the ring connector, is insert-molded within the entrance connector. The body ring provides appropriate spacing between the tip connector block and the ring connector.

Abstract: A self-adjusting rate-responsive pacemaker includes a conventional programmable pulse generator, a physiological sensor, and a processor, all packaged within an implantable case. The pulse generator generates heart stimulation pulses on demand, or as otherwise programmed, as controlled by a sensor-indicated rate signal. The sensor-indicated rate signal is derived from a raw signal obtained from the physiological sensor, and provides some indication of whether the heart rate should increase or decrease. The processor converts the raw signal to the sensor-indicated rate signal in accordance with a desired relationship (FIGS. 2, 3, 7A, 8). A minimum sensor signal value sets the minimum rate at which the pacemaker generates stimulation pulses, and a maximum sensor signal value sets the maximum rate at which the pacemaker generates stimulation pulses.

Abstract: A pacemaker mediated tachycardia (PMT) is detected by circuitry within an implantable pacemaker. The PMT is detected by first detecting a tachycardia condition that includes a prescribed number of consecutive cardiac cycles having a rate faster than a prescribed rate. Each cardiac cycle of the tachycardia condition includes a natural atrial event, i.e., a P-wave, and a paced ventricular event, i.e., a V-pulse generated by a pacemaker. After the prescribed number of such cardiac cycles, e.g., two to ten, a P-V delay in a single cardiac cycle is modified by a first prescribed amount, e.g., 50 milliseconds. The time interval of a V-P interval associated with at least one cardiac cycle preceding the modified P-V delay is then compared to a V-P interval immediately following the modified P-V delay. Only if the difference between the V-P intervals thus measured is less than a second prescribed amount, e.g., 25 milliseconds, is a PMT indicated. If a PMT is indicated, a PMT termination regimen, e.g.

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: An improved telemetry system for telemetering digital data from an implantable tissue stimulator such as a heart pacemaker. A carrier signal is pulse modulated in accordance with either or both of stored digital data and a digitized electrocardiogram signal, for coupling onto an electrical lead connected directly to the heart. This arrangement facilitates the transmission of substantially higher data rates than previously could be achieved.

Abstract: A flexible, planar patch electrode for cardiac defibrillation is fabricated from conductive wire mesh covered on an insulation side by a flexible layer of insulation. The electrode provides a substantial electrical contact area of 2-4 square inches and is shaped to provide an essentially rectangular base region with a plurality of protrusions extending longitudinally therefrom. he protrusions may be readily flexed to follow natural heart contours and slots between protrusions may be positioned to avoid features such as arteries near the surface of the heart. Central attachment of a lead within the base region minimizes current density and corresponding I.sup.2 R energy losses.

Abstract: A sensor for use with a rate-responsive pacemaker is disclosed which is responsive to blood oxygen content, thereby allowing the cardiac rate of the pacemaker to closely mimic the natural response pattern of the heart to changing physiological need. The sensor integrates the output from a photosensor driven by blood-reflected light from an LED, and when the integrated output reached a predetermined threshold latches the circuit, enabling the use of time to indicate the level of blood oxygen content. The sensor thus advantageously requires neither a voltage doubler in the driving circuitry, or an analog-to-digital converter in the output circuitry, reducing both complexity and power consumption of the blood oxygen sensor.

Abstract: A device for use as a rate-responsive pacemaker is disclosed in which the pacing interval is controlled by the average amplitude of a raw signal generated by a suitable physiological sensor and processed by an average amplitude converter to generate an output average amplitude signal coupled to the pacemaker control circuits to adjust the pacing interval. The average amplitude converter may be a rectifying amplifier and an integrating circuit, a voltage controlled oscillator whose frequency is measured over a suitable time interval using a time interval generator and a counter with the output of the counter being used by the control circuits of the pacemaker to vary its pacing interval, or means for measuring average amplitude of the raw signal and storing that measurement in memory and periodically processing it to alter the transfer characteristics of the rate-responsive pacemaker.