Abstract: There is disclosed a liquid velocity measuring apparatus comprising an actuable generator for providing a relatively high frequency signal to a transmitting transducer for directing an ultrasonic wave into a conduit through which liquid is directed. A receiver transducer is disposed to receive the acoustical wave as reflected from the liquid, and to provide an output signal to be amplified and demodulated to provide a train of high frequency pulses, the frequency of which is indicative of the velocity of the liquid directed through the conduit. The train of pulses is applied to a counter and a decoder for respectivey counting and decoding the pulses to provide a signal to a display whereby a digital indication of the liquid velocity is given.

Abstract: A body-implantable, intravascular lead affixed with a pin or pins at its proximal end adapted to be connected to a pulse generator and with an electrode or electrodes at its distal end electrically connected via conductor means and adapted to be securely and permanently attached to a body organ. Electrode means in the form of an elongated member having a circumferential electrode formed on one end thereof and an opening passing therethrough from its proximal to distal end is affixed to the distal end of the conductor means. Tissue securing means extending beyond the opening in the distal end of the electrode means are provided for securing the electrode means into firm engagement with the tissue at the desired location. Movable means located in the opening in the electrode means are provided for protecting the tissue securing means from causing injury to a body vessel, heart valve, or other tissue as the lead is inserted and guided through a vessel to the desired location.

Abstract: A set of heart stimulator leads including first and second leads is disclosed for respectively stimulating and sensing the atrium and ventricle of a patient's heart. The proximal end of each of the aforementioned first and second leads is associated with a heart pacemaker of the atrial-sensing, ventricular-inhibited (ASVIP) or sequential type, both of which have leads that are attached to the atria and ventricles. It is critical to ensure that the first and second leads associated respectively with the atrium and ventricle of the patient's heart, are not interchanged, which condition could possibly cause arrhythmias and morbidity, and is ensured by configuring the proximal end of each of the first and second leads so that both of these leads may not be inserted into the incorrect openings or bores of the pacemaker at the same time.

Abstract: A body implantable stimulator having a signal generator and lead electrically and mechanically interconnected by a preformed connector. The connector carries terminals to establish electrical communication between the signal generator and the lead, passageways being provided in the connector body to accept and guide the signal generator output connections and lead into contact with the terminals. In a preferred embodiment, the terminals are provided with intersecting bores such that an output connection and lead contact each other within a terminal. The preformed connector may be mechanically fastened to the signal generator.

Abstract: Electrical lead wire connection to a tape electrode is disclosed. Such electrodes are used for transmitting electrical signals through skin. The tape electrode includes a porous substrate material carrying a conductive layer comprised of finely divided silver metal suspended in a "dry" adhesive. An electrical lead wire is connected to the conductive layer of the tape electrode by a flat cover member having the same conductive layer on both sides thereof as is carried by the substrate of the tape electrode. One of the conductive layers of the cover member secures the lead wire to the conductive layer of the tape electrode. The other conductive layer of the cover member intimately contacts the skin along with the conductive layer of the tape electrode to provide for good electrical contact therewith when the tape electrode is applied thereto. The adhesive is normally "dry" and is activated at the time of application by a suitable solvent.

Abstract: Apparatus for stimulating body tissue and in particular the heart, is disclosed as including a device or circuit responsive to the initiation of stimulation and/or to the failure or pending failure of a component of the stimulating apparatus to provide the patient with a perceivable stimulation to a second, different portion of body tissue. There is disclosed an impedance level detector for sensing the impedance presented between the outputs of the stimulation apparatus to provide a warning signal indicating that the output impedance falls outside a predetermined range. In particular, the impedance level detector output is sensed by a stimulation control logic to apply a first train of pulses at a first rate to an auxiliary electrode for stimulating the second portion of tissue.

Abstract: A centrifugal blood pump and method of pumping blood is disclosed to provide assistance for a dysfunctional heart. The pump is provided with a magnetic drive system which permits a synchronous magnetic coupling with a separate power unit disposed immediately adjacent the pump housing. The pump has a single moving part which includes the combination of an impeller connected to a magnetic drive rotor. The impeller is of improved blade and hub design to automatically move blood, and minimize formation of blood clots and fibrous amalgamation in the region of blood flow. Further, the impeller blades are configured to extend almost completely across the bottom surface of the impeller hub to enhance efficiency and clot-free operation. The magnetic drive system floats on a fluid surface of saline solution, which hydrodynamically supports and lubricates the magnetic drive rotor contained in a compartment separate from the impeller and facilitates a prolonged period of service-free operation.

Abstract: A body implantable, intravascular lead affixed with a pin or pins at its proximal end adapted to be connected to a pulse generator and with an electrode or electrodes at its distal end adapted to be placed in contact with the endocardium. An electrical conductor(s) encased within a nonconductive material substantially inert to body fluids and tissues electrically connects the electrode(s) with the pin(s) and is comprised of a first length of resilient conductor having a first flexibility and an axial mechanical loading characteristic and a second length of the conductor having a second flexibility greater than the first flexibility and incapable of sustaining the axial mechanical loading characteristic. A dumbbell shaped electrode body provides sufficient size and weight to maintain the distal end of the lead in the apex of the right ventricle.

Abstract: A digitally controlled pulse generator includes a low frequency oscillator and a high frequency oscillator and logic means responsive to said oscillators so that the time between stimulating pulses provided by such pulse generator is determined by the low frequency oscillator and the width of the stimulating pulse is determined by the high frequency oscillator. In addition, logic means are included for comparing the frequency of the low frequency oscillator against the high frequency oscillator to insure against pacemaker runaway.

Abstract: A liquid velocity measuring system is described utilizing ultrasonic waves to measure the velocity of a liquid and in particular, the velocity of blood as directed through a conduit external of the patient's body. The liquid velocity measuring system comprises an ultrasonic soundwave transmitting transducer energized by a continuous wave generator, preferably at a frequency of 3.13 MHz. The transmitting transducer is disposed with respect to the conduit such that the transmitted ultrasonic waves are backscattered or reflected from ultrasonic reflection centers in the blood. This signal is received and detected by a second ultrasonic transducer. The reflected ultrasonic wave is frequency-shifted dependent upon the velocity of the liquid directed through the conduit and is detected by the second transducer to be amplified and demodulated subsequently, before being applied to a microbubble detection circuit in accordance with the teachings of this invention.

Abstract: Apparatus for indicating end of battery life in a cardiac pacemaker. A battery voltage monitoring circuit provides an indication of battery voltage drop below a predetermined level. A counter circuit and decode logic respond to the voltage drop indication to block a portion of a predetermined number of the generated pacing pulses from the heart to induce a benign arrhythmia in the heart thereby indicating end of battery life. In another embodiment a plurality of voltage sensors indicate progressive decreases in battery voltage and are connected with decode logic to block an increasing number of pacing pulses to indicate worsening battery condition.

Abstract: A pulsed energy coupling system for transferring energy from a detachable power source to a pulse generator module of an electromedical device. Periodically energy is transferred through coupling members to an energy storage device in the pulse generator module. Leakage current losses between coupling members at different electrical potentials is minimized by maintaining coupling members at the same potential during the time intervals between energy transfers. Energy transfers are triggered and effected either at independent, fixed intervals or as energy necessary to power the pulse generator module is dissipated from the energy storage device.

Abstract: A body-implantable, intravascular lead affixed with a pin or pins at its proximal end adapted to be connected to a cardiac pacemaker pulse generator and with an electrode or electrodes at its distal end adapted to be securely and permanently attached to a body organ through endothelial tissue. An electrode in spiral shaped form of a rigid, electrically conductive helix with a sharp tip at the distal end of the lead is adapted to be screwed through endothelial tissue into the body organ by means of a rotational motion applied to the conductor at the proximal end of the lead.

Abstract: A demand anti-arrhythmia pacemaker having a plurality of electrodes adapted for connection to a heart for sensing depolarizations. A first responsive circuit provides stimulation signals to at least one area of the heart if a depolarization corresponding to a natural heartbeat fails to occur within a first predetermined time period. A second responsive circuit provides stimulation signals to the heart in a plurality of areas in response to sensed depolarizations which occur within a second predetermined time period.

Abstract: A tape electrode usable for the transmission of electrical signals into the human body through the skin. The electrode is flexible in construction so that it may be applied to the skin to secure good electrical contact therewith and remain in place for extended periods despite movement, perspiration and the presence of water on the skin surface. The tape construction includes a surface of a conductive material combined with an adhesive on one surface and the conductive material with a magnetic powder on the second surface together with a coupler through a permanent magnet or magnetic substance to which a lead wire is connected to effect electrical connection through the conductive material in the adhesive and retain the lead wire in position through the magnetic attraction of the permanent magnet to the magnetic material.

Abstract: A body implantable device for providing electrical stimulation to living animal tissue. The device includes a pulse generator having at least one alterable output parameter and circuitry responsive to first externally generated signals for altering the alterable output parameter in predetermined correspondence with the number of said first signals. The output parameter altering circuitry is enabled only during the occurrence of second signals having characteristics discriminable from the characteristics of the first signals. In a preferred embodiment, the first signals are pulses of radio frequency energy and the second signals are magnetic. The invention may be embodied in a cardiac pacemaker of either the asynchronous or demand type and the second signals may be employed to cause a demand cardiac pacemaker to revert to an asynchronous operation.

Abstract: A pacemaker has circuitry which allows the time between the detection of an atrial contraction and the provision of an electrical stimulus to cause a ventricular contraction to vary with the rate of the sensed atrial contractions. The circuitry includes a differential amplifier having a reference voltage applied to one input and a capacitor coupled to the second input. The capacitor is charged from the time the atrial contraction is sensed to the time the charge equals the reference voltage, at which time the electrical stimulus is provided and the capacitor is discharged between the time the electrical stimulus is provided and the next atrial contraction is sensed. As the heart rate increases, the time between the atrial contractions decreases, and thus the capacitor discharges for a shorter time, or in other words, to a larger voltage and the time required for the capacitor to recharge to the reference voltage becomes less.

Abstract: The invention is to an electrochemical power cell construction utilizing a spring biased closure for the cell which prevents electrolyte leakage; the whole assembly being encapsulatable in a rigid material such as epoxy resin without loss of the spring biased seal.

Abstract: A synchronous artificial cardiac pacemaker having a first electrode adapted to be coupled to the ventricle of a patient's heart to pick up ventricular heart activity and to conduct stimulating pulses to the ventricle, a second electrode adapted to be coupled to the atrium of a patient's heart to pick up atrial heart activity and a pulse generator powered by a battery power source and coupled to the two electrodes and to an indifferent electrode. The pulse generator includes a timing circuit that, in the absence of any heart activity for a predetermined maximum time interval, produces stimulating pulses at a lower base pacing rate. The pulse generator also includes a first sensing circuit coupled to the ventricular electrode and a reset circuit coupled to the timing circuit. Natural ectopic heart beats indicative of ventricular activity are picked up by the ventricular electrode, sensed by the sensing means and applied to the reset circuit which resets the operation of the timing circuit.