Abstract: A multiple channel medication infusion system is disclosed which has a plurality of disposable pump cassettes mounted on a single main pump unit, thereby making the system compact and resulting in an economic system. The system has a printer which may be connected to the main pump unit to provide a printed record of system operation. Several modes are accessible to set up and program the system, to monitor actual system performance, and to test the system or display warnings indicating system malfunctions or that new cassettes should be installed.

Abstract: A mechanical drive system for use in driving a disposable cassette containing a reciprocating fluid pump and active valves from a main pump unit is disclosed which utilizes a single power module cam to drive both the reciprocating pump and the valves. By using a unitary power module cam, the system completely eliminates the possibility of a timing error between the operation of the reciprocating pump and the valves. A one-way clutch is used to prevent the system from slipping into a reverse operation, and the operation of the valve actuators prevents the possibility of free flow through a cassette installed onto the main pump unit.

Abstract: A pacemaker connector system for the coaxial heart lead of a bipolar pacemaker consists of two connector block assemblies housing circular springs which circumferentially grip the central and outer terminals of the lead. Protruding ends of the springs are covered by rubber septum buttons which, when depressed, open the spring interiors to allow insertion of the heart lead. The problems associated with set screw systems are eliminated, and improved mechanical and electrical contact over other types of spring systems is provided.

Abstract: A telemetry system for use with implantable medical devices is disclosed which utilizes both in-phase and quadrature data components, and frequency modulates both data components into a single transmitted sinusoidal signal which varies in frequency between two selected frequencies. The signal is received and decoded, preferably by a coherent decoder, into in-phase and quadrature components, which are then integrated and sampled to produce the two transmitted in-phase and quadrature data components, which may then be recombined to produce the transmitted data. The system requires only low power, and is capable of operating at a relatively high data rate while retaining a high degree of accuracy due to the splitting of the signal into the in-phase and quadrature data components.

Abstract: An improved clamp fixture is provided for supporting a medical instrument or the like in a selected orientation relative to a variety of different support structures, such as an upright pole, a tabletop edge, a bed rail, etc. The clamp fixture comprises an open-sided base bracket for receiving the selected support structure to extend through the base bracket along a first axis. A clamp screw is carried by the base bracket and is adjustable to securely retain the support structure against an inner support surface of the base bracket. A frame member is mounted on the base bracket for rotation generally about a second axis perpendicular to the first axis, with a spring-loaded lock pin releasably securing the frame member in one of several preset rotational positions. At least one frame arm extends outwardly from the frame member for connection to the medical instrument or the like in a manner permitting rotation of the medical instrument about a third axis perpendicular to the first and second axes.

Abstract: A test device for use with a pacemaker to simulate the load of a heart. The device is designed for telemetering control and includes in its circuit a magnetic reed switch which opens and closes a load circuit in response to a remotely applied magnetic field. The device is intended to be disposable and is installed in circuit with the pacemaker terminals which normally connect to the heart leads. The device as thus installed is packaged in the sterile shipping package with the pacemaker and both permit the final checking of the pacemaker within its sterile pack prior to shipment and testing of the pacemaker in preparation for implantation without the necessity of opening the sterile package to conduct the test.

Abstract: Circuitry for quantitatively determining the level of processed heart signals relative to actual sensing sensitivity level (threshold) in an implantable pacemaker. The measurement is useful for adjusting the settable threshold, polarity, filtering or amplification parameter settings for safe operation and noise rejection of the pacemaker.

Abstract: Programmable timing and logic circuitry is provided to detect crosstalk between paced chambers of the heart and to provide compensation in the event crosstalk is detected. Signals sensed during a prescribed time window early in the cardiac cycle following an atrial pulse are presumed to be crosstalk. If crosstalk occurs, a shortened AV delay is triggered. If crosstalk does not occur, a programmed AV delay is maintained. Absent the occurrence of a ventricular event after the prescribed time window up to the end of the AV delay, a ventricular stimulation pulse is provided. If a ventricular event is sensed during this time, the ventricular stimulation pulse is inhibited.

Abstract: An implantable catheter for use in delivering insulin or other therapeutic fluids is disclosed which uses a novel terminator design to prevent the growth of fibrotic tissue from obstruction the catheter. The catheter takes advantage of fibrotic encapsulation by utilizing a depression in the surface of the terminator which will effectively keep fibrotic tissue spaced sufficiently away therefrom to allow fluid to be infused. In addition to being capable of long term implant, the catheter is implantable in the omentum, enabling the body's natural absorption of insulin to be successfully mimicked.

Abstract: A medication infusion system having a disposable cassette including a piston pump and active valves for installation on a main pump unit including a mechanical drive system for operating the cassette is disclosed which has a unique system for loading the cassette onto the main pump unit and latching the cassette in place on the main pump unit. The cassette includes a slide latch which closes the fluid path when the cassette is to be installed, the slide latch only being opened when the cassette is properly installed on the main pump unit with the valve actuators of the main pump unit preventing fluid freeflow. Latching the cassette in place causes a latch head on the main pump unit to grasp the piston on the cassette in a driving relationship.

Abstract: A system for determining P-wave or R-wave capture in response to pacemaker supplied electrical stimuli. One embodiment includes a conventional bipolar atrial lead having a tip electrode, connected to an atrial pulse generator circuit within an implantable pacemaker, and a ring electrode, spaced apart from the tip electrode, connected to a P-wave sensing EGM amplifier within the pacemaker. The bandpass characteristics of the P-wave sensing EGM amplifier allow detection of all electrical frequencies in the atrium within the bandpass chosen. The output signal from this amplifier is selectively telemetered to an external receiver, as is a signal indicating the generation of an atrial stimulation pulse, where the occurrence of atrial stimulation pulses and P-waves can be monitored. In operation, if constant time intervals between the monitored atrial stimulation pulses and P-wave occurrences are present, P-wave capture has occurred.

Abstract: An implantable medical sensor (42) determines the oxygen content of blood. The sensor includes a miniaturized hybrid circuit (130) that includes light-emitting diode means (32), phototransistor means (34, 36), and a substrate (110) to which the light-emitting diode means and phototransistor means are bonded in a desired circuit configuration. The hybrid circuit is hermetically sealed within a cylindrical body (140) made from a material that is substantially transparent to light, such as glass. Feedthrough terminals (132, 134) provide means for making an electrical connection with the hybrid circuit. The light-emitting diode means is driven with a stair-stepped current pulse. In one embodiment, the sensor is embedded within a bilumen pacemaker lead (60) and positioned near the distal electrode (66) of the lead so that the sensor resides within the heart when the lead is implanted within a patient, thereby allowing the sensed oxygen content (MVO.sub.

Abstract: A power converter for use in converting a variable DC input voltage into a variable DC output voltage is disclosed which uses control circuitry on both the input and the output to optimize converter performance. By charging the inductor up nearly to the saturation point, but completely avoiding saturation of the inductor, power capability at the input end is maximized. By discharging the inductor completely without either losing power capability by continuing to attempt to discharge the inductor after the charge is depleted or by failing to nearly discharge the inductor thereby presenting the possibility of saturation to the boosting of current through the inductor during the next charge cycle.

Abstract: An analyzer-programmer system (30) for use with an implantable medical device, such as a cardiac pacemaker (20). The system facilitates non-invasive communications with the implantable device and makes analysis of the operation of the implantable device easier to understand and perform. The system includes conventional processor means (42) for processing a sequence of stored instructions stored in programmable read-only memory, or ROM (40). The ROM, although designed to be accessed through predefined page of information, and blocks within such pages, is configured to allow in-page addressing within any of a plurality of pages in a linear fashion. Programmed intervals to be sent to the implantable device are displayed by the system in tabular form or as scaled time-lines or bars (FIG. 9A), with each separate interval beginning and ending in proper timed sequence, thereby providing a prediction of the expected performance. Such programmed intervals can overlay or sidelay measured performance (FIG.

Abstract: A disposable cassette for use with a main infusion pump unit is disclosed which contains both a disposable pump and a battery, thereby requiring the simultaneous replacement of both the pump and the battery. The controller contained in the main pump unit includes a timer which prevents the cassette from being used for longer than a predetermined time, which is substantially less than the life of the battery. An interlock prevents a cassette from being reinstalled following a single use.

Abstract: An enclosure for use to safely secure a water-sensitive medical or electronic device such as a medication infusion pump in a water-resistant manner is disclosed which utilizes a pouch made of a sheet of thin plastic material to store the apparatus, the pouch being adhesively sealable to secure the device. The enclosure also includes a perforated area which may be opened to form a strap to carry or hang the device, and is constructed inexpensively to be of a disposable nature.

Abstract: A device for use in conjunction with a pulse generator is disclosed which provides a variable pulsing rate in response to short term variations in arterial blood pressure, like the baroreceptor system of the healthy body's cardiovascular system. The system utilizes a pressure transducer implanted together with the pacemaker, the transducer is preferably located on the proximal axillary artery. The system features quick response based on physiological need, and also includes a reset feature which maintains a normal resting heart rate despite long term changes in blood pressure.

Abstract: An apparatus for interpreting and displaying cardiac events of a heart connected to an implanted cardiac pacing means (2) is disclosed. The apparatus includes a telemetry head (4), at least one interpreting means (6), and a controller (14). Information telemetered from the implanted pacing means is separated into identifiable sets of data pertaining to prescribed functions, such as atrial events, ventricular events, pacemaker timed events, sensor events, and the like. Skin ECG information may also be received through another interpreting means (12) in addition to pacemaker telemetered data. Parallel processing channels are employed to process all the received data while maintaining synchronization therebetween. Memory means (16) allow the synchronized processed data to be stored for subsequent print out through a D/A converter (20) and printer (22), or to be displayed on a display monitor (26).

Abstract: An atrial tracking dual-chamber pacemaker and method of use for reducing the risk of initiating a pacer mediated tachycardia (PMT), and breaking such a PMT if once started. The pacemaker includes means for sensing a premature ventricular contraction (PVC). The pacemaker operates in a conventional manner unless a PVC is sensed. If a PVC is sensed, in accordance with one embodiment, an extended atrial refractory period is triggered in an attempt to block any retrograde atrial events resulting from the PVC. This is followed by an atrial alert time window. After a prescribed A-V delay subsequent to the timing out or other termination of the atrial alert time window, a ventricular stimulation pulse is generated, unless prior ventricular activity is sensed that inhibits such ventricular stimulation pulse.

Abstract: A rate-responsive pacemaker includes a motion sensor mounted therein. The output signal from the motion sensor is a digital signal that can be connected directly to the digital processing and control circuits of the pacemaker in order to adjust its basic pacing rate as a function of the physical motion or activity that is sensed. The motion sensor includes an enclosed housing having a conductive element therein that partially fills the space of a cavity within the enclosed housing. The conductive element is free to roll, flow, or otherwise move around the inside of the housing in response to external forces. The external forces that cause the conductive element to move include the physical motion of the patient as well as the force of gravity. As the conductive element moves within the enclosed housing, it makes electrical contact with at least two of three electrodes that are selectively spaced around the inside periphery of the housing.