Abstract: A linear motion, muscle-actuated cardiac assist device novelly uses a powering muscle whose contractions and relaxations are made in a substantially linear fashion, as opposed to the curvilinear muscle motions associated with prior art muscle-actuated cardiac assist devices. As a result, collateral circulation of the powering muscle need not be cut, theoretically leading to prevention of ischemia in the powering muscle. Other benefits include: greater energy efficiency of the powering muscle; greater available choice of powering muscles (i.e., not limited to the latissimus dorsi as the powering muscle); and reduced profile height of the cardiac assist device to reduce protrusion from the implanted area of the body.

Abstract: One aspect of this invention relates to a temporary heart wire, and external connector therefore, and the combination of the two, wherein the distal end of the heart wire includes a temporary affixation coil (8) and distal pacing (2) and sensing (1) electrodes connected by means of a coaxial helicoidally wound cable (3) to a proximal electrode (7) and a breakaway needle (6) which also serves as a proximal electrode. The lead is adapted to be inserted into a disposable connector having a snap aperture element (19) for receiving the breakaway needle, and about which the needle is broken, as well as electrical contacts (17, 18) for contacting the proximal electrodes and adapted to be connected to a temporary external pacemaker. According to another aspect of this invention, there is provided a permanent bipolar nerve electrode which includes two electrodes (52), (54) adapted to be positioned along the nerve trunk (58).

Abstract: In order to terminate pacemaker-mediated tachycardia (PMT), a pacemaker (or "Pacer") capable of atrial synchronized ventricular pacing, defines a retrograde sensing window after a ventricular paced event. If a preset number of sequential retrograde sensed events occur within this window in consecutive pacing cycles the post ventricular atrial refractory period (PVARP) is extended for one pacing cycle (EXT PVARP) and the pacer will not attempt to interrupt a PMT for a relatively long preset interval thereafter.

Abstract: A pacemaker having a hysteresis feature which permits intrinsic heart activity, controlled by the sinus node to resume optimally after pacing. The pacemaker has a programmable lower rate and upper rate, a programmable lower hysteresis rate (LRH) corresponding to a lower rate hysteresis interval (LRHI), and a programmable rate (IR) intermediate an upper pacing rate (UR) and a lower pacing rate (LR). A microprocessor measures the average rate of change M.sub.AVG in the intervals between consecutive ventricular depolarizations, and compares the last intrinsic escape interval RR.sub.N to the lower rate hysteresis interval (LRHI).If the last intrinsic escape interval RR.sub.N is longer than the lower rate hysteresis interval (LRHI), and if the value of M.sub.AVG is greater than a first preselected value SL.sub.1 but less than a second preselected value SL.sub.2, the pacemaker stimulates at the lower rate hysteresis (LRH) and thereafter gradually increases the pacing rate up to the intermediate rate (IR).

Abstract: Regulators for improved cardiac assist systems of the type including skeletal muscle powered fluid pressure means, a cardiac cup and/or an aortic balloon pump. The regulators convert the positive pressures generated by contracting muscle into both positive and negative pressures useful in the systems.

Abstract: An improved electrode for establishing electrical contact with a nerve of a patient. This electrical contact may be used to sense neural activity on the nerve or to artificially stimulate it to perform various medical treatments. One embodiment of the electrode has an outer cuff of an insulating material which is sutured around the nerve to be contacted. A drug impregnated layer of material is positioned inside of the outer cuff. This material is a polymeric matrix which permits the drug to leach out at a predetermined rate. The drug is preferably a glucocortico steroid such as dexamethasone sodium phosphate. The actual electrical contact is produced by metallic foil which is positioned on the surface of the drug impregnated layer of material which is located inside of the cuff. A second embodiment employs a half cuff which is held in contact with the nerve tissue by being sutured to muscle tissue. The insulative substrate of the half cuff is a drug impregnated polymeric matrix.

Abstract: A pacemaker having two bipolar leads, one atrial, one ventricular, each with TIP and RING electrodes, configured as for conventional bipolar pacing/sensing in both chambers. Switching circuitry in the pacemaker is operable to select from among various possible sensing configurations, including one configuration in which sensing is performed between the ring electrodes of the respective pacing/sensing leads. Pacing is preferably performed in a conventional unipolar configuration in each chamber, from the respective tip electrodes. The "ring-to-ring" EGM signal is applied to filtering and EGM amplifier circuitry, and then provided to a telemetry system for transmission to an external receiver. The ring-to-ring EGM signal possesses the high resolution properties of conventional intracardiac signals, and is relatively unaffected by the after-potentials and tissue polarization effects that arise when the same lead is used for pacing and sensing.

Abstract: A conical annulus formed on a pacer lead body engages a deformable retention ring formed on the connector block to hold the lead in the pacer.

Abstract: A temporary heart wire, and external connector therefore, and the combination of the two, wherein the distal end of the heart wire includes a temporary affixation coil (8) and distal pacing (2) and sensing (1) electrodes connected by means of a coaxial helicoidally wound cable (3) to a proximal electrode (7) and a breakaway needle (6) which also serves as a proximal electrode. The lead is adapted to be inserted into a disposable connector having a snap aperture element (19) for receiving the breakaway needle, and about which the needle is broken, as well as electrical contacts (17, 18) for contacting the proximal electrodes and adapted to be connected to a temporary external pacemaker. In an alternate embodiment, there is provided a permanent bipolar nerve electrode which includes two electrodes (52), (54) adapted to be positioned along the nerve trunk (58).

Abstract: A multi-axis, multi-purpose sensor for use with implantable medical devices, and for simultaneously detecting the patient's posture and activity level. The sensor includes a hermetically sealed, fluid-tight, bio-compatible housing. The housing is formed of a plurality of adjacently secured sides, and a plurality of side electrodes coupled to the sides. A central electrode is disposed at the geometric center of symmetry of the housing, to allow measurement of voltage changes between the central electrode and the side electrodes. A non-toxic electrically conductive electrolyte fills about half the housing, and immerses part of the central electrode and the side electrodes. The sensor further includes a low frequency bandpass filter for passing low frequency signals indicative of the patient's posture, and a high frequency bandpass filter for passing high frequency signals indicative of the patient's activity.

Abstract: A test driver for connecting a controlling computer to an IC chip having a standard test access port (TAP) is both hardware and software efficient. The last stage of a wrap-around or circulating control register feeds a test mode select (TMS) pin of the TAP, and feeds the next-to-the-last stage back to the first stage. As a result of the control register configuration, the control register's original contents are automatically restored after each shift, cycle, thus abrogating the need to reload the control register if the same control pattern is again needed, and abrogating the need to maintain (via software) the correct value on the TMS pin in between shifting sequences of the control register. Proper shift times in a data register of the test driver are achieved by replicating the IC chip TAP controller state machine.

Abstract: A pacemaker system includes a dual sensor implantable pacemaker and an external programmer for automatically and simultaneously optimizing and initializing a plurality of pacing parameters. The pacemaker includes means for automatically initializing a sensitivity threshold, pacing pulse width, pacing pulse amplitude, activity threshold, and pressure rate response gain setting.

Abstract: An implantable heart-assist device including extra-aortic balloon pump (EAB pump) for use in cooperation with a fluid pump is disclosed. The extra-aortic balloon pump includes a rigid, generally cylindrical housing and a flexible, generally cylindrical diaphragm residing generally within a longitudinal passageway in the rigid housing and secured to the rigid housing so as to create a plurality of separate expansion chambers. A plurality of fluid communication ports are provided for passing fluid into and out of the respective expansion chambers. The rigid housing includes interior and exterior surfaces, proximal and distal ends, and a longitudinal passageway. The diaphragm has an inner surface which defines a longitudinal lumen within the longitudinal passageway. The longitudinal lumen has a longitudinal axis and the respective expansion chambers and corresponding fluid communication ports are oriented axisymmetrically in respect to the longitudinal axis.

Abstract: A method and apparatus for introducing gradual changes to an audio signal so that the changes are subliminal. The changes can involve tempo and volume, for example, and can take the form of a gentle gradient having ever increasing/decreasing ramp-like changes over a sufficient duration, or a more complex program involving several gentle gradients. In the preferred embodiment, an enhanced audio play-back device such as a portable audio cassette recorder can be programmed to subliminally alter the characteristics of a standard pre-recorded tape containing music, for example. As a motivational tool during walking, jogging or other repetitive exercise, the tempo is gradually increased over a period of time to encourage a corresponding gradual (and subliminal) increase in physical exertion by a user whose rate of movement is proportional to the tempo of the music.

Abstract: A method and apparatus for providing assistance to a patient's heart using a surgically prepared skeletal muscle. A skeletal muscle, such as the latissimus dorsi, is carefully separated from the skeletal structure leaving enervation and vascularization in tact. The muscle tissue is then separated into two independent contractile masses. Alternatively, two separate skeletal muscles may be used. The first of these is wrapped about the atria. The second is wrapped about the ventricles. Each muscle mass is individually stimulated using an implantable pulse generator. Stimulation to the muscle mass is synchronized to the naturally or artificially paced contractions of the heart to provide the maximum in assistance. During each complete heart cycle, the muscle mass assisting the ventricles is stimulated at the same time as contraction of the ventricular myocardium. The muscle mass assisting the atria is then stimulated at the same time as contraction of the atrial myocardium.

Abstract: In a high speed digital computer data transfer system, a data bus driver reduces data bus voltage swings between logic high and logic low levels by defining minimum and maximum bus voltages which lie between said logic levels, thus lowering bus transition and hence data transfer times. Positive and negative overshoot of the reduced bus logic levels are prevented by "clamping diode" transistors. The data bus driver assumes a tri-state mode when not transmitting data, during which the clamping diode transistors also eliminate positive and negative bus voltage overshoot. The preferred embodiment is implemented using complementary metal-oxide-semiconductor (CMOS) technology.

Abstract: In a multiple-board computer system, diagnostics are primarily performed by highly reliable microcontroller units (MCUs) on each processor (and memory) board. Operated separately from the board central processing units so that board failure will not prohibit diagnostic routines, the MCUs are serially connected to a bus separate from the main bus. Redundant diagnostic processor board MCUs constantly monitor the other MCUs and the serial bus, and oversee the operation of an MCUs on a malfunctioning board. In an alternate embodiment the diagnostic processor boards are replaced by a microcomputer serving as a monitor.

Abstract: The present invention couples a disk drive to a small computer system interface bus by means of two buffers connected between a buffer-in bus and a buffer-out bus to allow data to be read out from a first filled buffer onto the buffer-out bus, while simultaneously permitting a filling of the second buffer from the buffer-in bus. When the second buffer is full and the first buffer is empty, the second buffer may be read while the first buffer is again filled. Toggling between the two buffers continues until the required data transfer is complete.