Abstract: An implantable blood flow sensor for measuring a blood flow rate through a blood vessel within a person's body. The flow sensor includes a rigid cylindrical tube, sized to fit within the blood vessel, a heater attached to the tube, and a pyroelectric detector located within the tube. A predetermined amount of heat energy is produced by the heater and the pyroelectric detector monitors the resultant temperature change and generates a temperature signal based on the temperature change. A processor generates a data signal, based on the temperature change, that indicates the blood flow rate through the blood vessel or artery. The rigid tube protects the pyroelectric detector from external forces that may produce unwanted signals due to piezoelectric effects. Additionally, the heater may be incorporated into one of the electrodes of the pyroelectric detector as a serpentine path in the electrode that forms a resistive heating element.

Abstract: A two-conductor bus system is provided to electrically interconnect a plurality of physiologic sensors to a pacemaker, each sensor being adapted for placement along a pacing lead. The conductors of the bus extend longitudinally through the insulating material of the lead, connecting to each sensor. The pacemaker provides a supply voltage on the bus to provide power to the sensors. The sensors modulate the supply voltage on the bus to transmit information to the pacemaker. This information may be used by the pacemaker to adaptively pace the heart. In one embodiment, the sensors include bus monitoring circuitry for receiving control signals from the pacemaker.

Abstract: In a method for manufacturing electrodes for medical applications, particularly implantable stimulation electrodes, having an active layer of porous titanium nitride, a substrate of electrically conductive material that is in an atmosphere containing titanium, nitrogen and hydrogen is irradiated with an excimer laser through an optical mask, and a structure of porous titanium nitride is deposited on the substrate.

Abstract: A defibrillator has a pulse-generating device with at least three outputs to which electrodes are connectable for delivering defibrillation pulses. A switching network is provided to reverse the polarity and/or to switch the voltages applied by the pulse-generating device, selectively and at predetermined times, among the electrodes.

Abstract: A device for heart therapy has a tacharrythmia detector unit, a control unit and a current generator. The current generator controlled by the control unit emits via an electrode system a first, pulsed current to a physiological representative of the parasympathetic nervous system in order to activate same in response to detection of an impending or established arrhythmia. The current generator is further caused by the control unit, in the event of tachyarrythmia detection to emit, via the electrode system, a second current to a physiological representative of the sympathetic nervous system in order to block same.

Abstract: An electrode apparatus, such as an intravascular or intracardiac pacemaker or defibrillation electrode with an electrode cable has a jacket of insulation enclosing a first elongated, flexible conductor, connected to a first electrode arranged on the electrode cable, and also enclosing at least a second conductor, connected to a conductive surface forming a second electrode arranged on the electrode cable at a distance from the first electrode.

Abstract: A low-power delta modulator analog-to-digital converter is provided that is suitable for use in a cardiac stimulating device for monitoring intracardial signals. The delta modulator consumes less power than previously available delta modulators because portions of the delta modulator circuitry are shut down when the signal to be digitized is not rapidly varying. The device uses slow clock pulses for sampling the input signal and subsequently digitizes the sampled signal using a faster clock. After a sampled signal has been digitized, the result is held until the next slow clock pulse. Power consumption is reduced since the delta modulator does not draw substantial amounts of power during this holding period. Further, the output of the delta modulator reflects the magnitude of the change in the analog input, with a separate bit for representing direction.

Abstract: An implantable stimulation device has a sensing amplifier circuit for amplifying low amplitude cardiac signals, while maintaining low power, to produce an output signal having a low noise level. The sense amplifier circuit includes a two-stage amplifier, a bandpass filter, and a threshold detector. The first stage comprises a linear differential amplifier which has low gain, good common mode rejection, and a current consumption proportional to the gain. The second stage is a switched-capacitor amplifier which has a programmable gain and low current consumption. The noise content of the system is low and produced substantially entirely in the switched-capacitor amplifier.

Abstract: For an implantable medical devices, a system is provided for welding electrically conductive ribbon, typically stainless steel, to electrically conductive wire, typically platinum, the melting point of steel being substantially lower than that of platinum. An aperture is formed in the ribbon having an opening smaller than that of the wire. The ribbon is engaged with the wire such that the aperture is generally coextensive with the wire. Thereupon, a pulse laser beam is directed transversely of the ribbon through the aperture and onto the wire to simultaneously melt the wire and the ribbon and to create a homogeneous mix of the molten steel and platinum in the region surrounding the aperture. Thereafter, operation of the laser beam is discontinued to allow solidification and thereby achieve a welded connection between the ribbon and the wire.

Abstract: A heart stimulator having a pulse generator and an electrode system, which contain at least one bipolar electrode with one pole arranged in the atrium and another pole in the ventricle, or at least two unipolar electrodes respectively arranged in the atrium and ventricle, for detecting atrial and ventricular activity includes an atrial measurement unit which is connected for measuring a signal between the two poles of the bipolar electrode, or between the two unipolar electrodes, and a ventricular measurement unit arranged to measure the signals between the ventricular pole (or electrode) and the housing of the stimulator.

Abstract: A combination lead for use with an implanted pulse generator which may be a pacemaker or defibrillator or combination thereof. The lead can deliver an electrical charge to pace, cardiovert or defibrillate the ventricles of the heart, and can sense cardiac activity in the heart. The lead includes atrial ring sensors capable of sensing electrical activity in the atrial cavity. The lead allows cardioversion and/or defibrillation stimuli to be provided by a large surface area electrode which is passively implanted in the ventricle, and allows the pulse generator to provide ventricular pacing appropriately synchronized to atrial depolarizations, cardioversion or defibrillation.

Abstract: An electrode device, for intracardiac stimulation and/or defibrillation of heart tissue and/or sensing heart signals in a patient, has a soft, flexible electrode cable with an outer coating of insulation containing at least one elongate conductor connected to an electrode arranged on the electrode cable. In order to attain an electrode device of this kind which is structurally very simple and in which all the electrodes on the electrode cable can be applied to the heart wall in a very simple manner so the entire electrode surface faces the wall and firmly presses against it, the electrode cable is at least partially ribbon-shaped.

Abstract: A device for shaping an electrode cable, such as a medical electrode cable for use with a pacemaker, includes a substantially tubular element or sleeve, having a length which is relatively short in comparison to the length of the electrode cable. The internal diameter of the tubular element is only slightly larger than the exterior diameter of electrode cable, so that the tubular element can be slid on and off the electrode cable. When the tubular element is on the electrode cable, it surrounds a portion of the electrode cable. The tubular element is curved in a desired manner, and is sufficiently stiff so that the portion of the electrode cable surrounded by the tubular element conforms to the shape of the tubular element. The device is extremely simple and inexpensive and simplifies adaptation of the electrode for placement in a patient's heart.

Abstract: An endocardial lead assembly, adapted to transmit electrical signals between a proximal end portion of the lead assembly and a distal end portion of the assembly and to thereby stimulate selected body tissue, includes at least two coiled, insulatively coated conductors extending between the proximal and distal end portions for transmitting the electrical signals. The coils of the at least two insulated conductors are contiguous and have substantially the same first outer diameter, one of the coiled conductors having a portion extending through said distal end portion of the lead and being electrically connected to said tip electrode. The remaining conductor(s) terminate at a proximal extremity of the distal end portion, the portion of the one coiled conductor within the distal end portion including contiguous, uninsulated coils having a second outer diameter that is less than the first diameter.

Abstract: A joint and method of making a joint for providing a secure mechanical and electrical connection between a longitudinally extending coiled or wound element and a terminal on a mating component in a body implantable lead assembly. The wound element has an end portion threadedly received by a post on the terminal. A ring is disposed about the end portion of the wound element. The ring, the end portion of the wound element and the post are joined at at least one location along the circumference of the ring, preferably by thermally fusing these parts using a pulsed laser. The ring has a thin wall and is preferably made of the same biocompatible metallic alloy as the wound element.

Abstract: An apparatus and method of electrochemically determining an oxygen concentration with an oxygen sensor that includes a working electrode. The working electrode has a potential profile that includes a first potential step (a first measuring potential), a second potential step (a second measuring potential) and a third potential step. A measuring period is provided at the first and second measuring potentials. The currents flowing at the first and second measuring potentials are calculated and integrated over time. One of the two measuring potentials may be varied, depending on the difference between the two integrals of the currents flowing at the first and second measuring potentials, until the two integrals equal 0. An oxygen concentration is then determined from the value of a potential which thereby results.

Abstract: An improved telemetry system for telemetering data from an implantable device such as a heart pacemaker to an external device with minimum energy consumption. The external device first sweeps its receiver across a predetermined frequency band, e.g., the fm broadcast band of 88 MHz to 108 MHz, to determine the particular frequency having the lowest ambient electromagnetic noise level, which it deems the optimum frequency for the telemetry to occur. The external device's transmitter then commands the pacemaker to telemeter a predetermined start signal at a succession of frequencies that sweep across that same frequency band, while the external device's receiver remains tuned to the optimum frequency. Eventually, the external devices receiver will receive the start signal and the external device thereupon will command the pacemaker to thereafter remain at its current frequency for the subsequent telemetry of data.

Abstract: A cardiac event and arrhythmia detection system and method detects arrhythmic cardiac activity or other information from an electrogram signal of a heart. The system senses the electrogram signal through an electrogram lead, preliminarily processes the signal, and converts it to a plurality of discrete digital signals, each of which represents the magnitude of the electrogram signal at a prescribed sample time. The discrete digital signals are applied to both a cardiac event detector and a morphology detector. The morphology detector detects selected changes in the morphology (shape) of the electrogram signal, wherein such changes automatically control the sensitivity (gain and/or threshold) used to detect cardiac events. The occurrence of a prescribed amount of change in the detected morphology over time indicates the occurrence of a prescribed arrhythmic cardiac condition.

Abstract: A flow sensor adapted for placement along a pacing lead or other catheter comprises a thermopile formed on the outer surface of a tubular substrate. The thermopile comprises a plurality of interconnected conductors of an alternating metal type. Junctions between conductors of the thermopile are alternately located near the longitudinal ends of the flow sensor, so that a voltage generated by the thermopile indicates the difference in temperature between the ends of the flow sensor. To measure blood flow with the flow sensor, an alternating current is induced through the thermopile to heat the flow sensor in a generally symmetrical manner. A voltage generated by the thermopile is then measured to obtain a sample of the magnitude and direction of the velocity of blood flow.

Abstract: The electrochemical cell includes an electrode structure having an aluminum current collector in combination with an active cathode material containing polycarbon monofluoride. The electrode structure also includes a polymeric separator and a lithium anode. The electrode structure is spiral wound and mounted within a cylindrical housing formed of conventional stainless steel. Care is taken to ensure that the aluminum foil isolates the polycarbon monoflouride of the cathode material from the stainless steel of the housing. The cylindrical housing is flooded with a non-aqueous electrolyte solution. The resulting cell is employed within an implantable medical device. In an alternative embodiment, electrode structures employing the aluminum current collector and the polycarbon monoflouride active cathode material are formed as rectangular plates and are mounted in parallel within a rectangular housing. In another alternative embodiment, the aluminum current collector is employed within a button cell.