Abstract: A single-pass body implantable lead for transvenous insertion through a single vein to simultaneously sense and/or stimulate the tissue of both the right atrium and right ventricle. The lead employs a single bifurcated connector at the proximal end. Insulated conductors for the ventricle and atrium are branched from a single outer sheath. The ventricular and atrial branches are established in fixed relation to one another. The ventricular branch is of sufficient length that it has excess length for the largest heart. The electrode of the ventricular branch is held within the right ventricular apex by tines. The atrial branch has a "J" shape imparted to the conductor coil. The atrial electrode is maintained in position within the right atrial appendage by tines. The ventricular branch is sufficiently flexible such that any excess length is merely coiled in some convenient position.

Abstract: A cardioversion and defibrillation lead system and a method of use of the lead system for applying energy to the heart. The lead system and method of application are designed to maximize the efficiency of electrical energy and depolarizing the cells of the heart by equalizing current distribution across the heart and concentrating current in the muscular areas of the heart. The method of use of the lead system includes properly locating the electrodes, and applying pulses to the electrodes in one of several pulse regimes.

Abstract: A body implantable lead having multiple spatially displaced electrodes to facilitate the sensing of current vectors in muscle tissue. The lead employs three mutually orthogonal electrode pairs. Each electrode pair is capable of measuring current vectors within the muscle tissue in a different one of three mutually orthogonal directions. All six electrodes are mounted about a single cylindrical lead body. Each of the six electrodes is coupled to an in-line electrical connector at a proximal end of the sensing lead. Because the electrodes are relatively closely spaced on a convenient size lead, being of about 8-14 French in diameter, state of the art processing techniques are required to resolve the direction of current flow within the heart muscle.

Abstract: A monitoring circuit for use in conjunction with an electrical stimulator and an electrical monitor, such as an EKG monitor, having a differential amplifier input. The circuit functions by equalizing the electrical signals due to the stimulator on both inputs of the electrophysiological monitoring device. Because the stimulator induced signals appear at equal levels on both inputs, the differential amplifier of the monitoring device will cancel them out, allowing display of the underlying physiological signals.

Abstract: A nonaqueous cell comprising an active metal anode, such as a lithium, sodium, potassium, calcium or alloys, a liquid cathode-electrolyte comprising a solute dissolved in a solvent which, in a preferred aspect, is an oxyhalide of an element of Group V or Group VI of the Periodic Table and wherein the surface of the anode contacting the cathode-electrolyte is coated with a polymeric film having ether linkages. In a preferred practice of the present invention, the anode is coated with polyethersulfone.

Abstract: A body implantable lead for the delivery of stimulation energy to a desired body site including a drug dispenser carried by the lead which retains a drug to be dispensed while allowing the dispensing of that drug at least adjacent the desired body stimulation site. The lead is provided with an electrode having a bore open to a drug storage chamber which contains an absorbent plug. The drug is loaded into the absorbent plug, prior to use, by soaking the electrode in a solution containing the drug.

Abstract: A connection system for joining a medical electrical stimulator to its electrical stimulus delivery system features a first member having a row of more than two contact surfaces each spaced apart a given distance from the adjacent contact surfaces, and a second member having at least the same number of contacts in a row each spaced from the adjacent contact surface by a multiple of the spacing between the contact surfaces of the first member and each being connected to one of two electrical conductors so that electrical connections between the contact surfaces are varied as the two connector members are relatively moved along the rows.

Abstract: An improved flow through ion sensing electrode and a method for producing it. The electrode is formed of bilumen plastic tubing using one lumen as the sample path and the other lumen as a sensing chamber. By permeating a portion of the tubing with an ion selective material, an ion selective membrane integral with the chamber wall is produced. A preferred embodiment also incorporates a reference electrode.

Abstract: A pacemaker sense amplifier circuit exhibiting a very high common mode rejection ratio for detecting intracardiac electrogram signals is disclosed. The circuit includes a sampling capacitor which is differentially charged by the intracardiac signal. The voltage stored on the sampling capacitor is periodically applied to a high input impedance differential voltage amplifier which is referenced to the battery ground. The signal is smoothed and reconstructed by a bandpass filter, and is applied to a comparator to generate a logic level pulse indicative of the occurrence of a cardiac depolarization.

Abstract: An implantable medical device to deliver cardioverting energy to cardiac tissue in synchrony with detected ventricular depolarizations having a low power sensing and control circuitry and high power cardioversion circuitry, sharing a common lead and interface circuitry. The lead possesses a superior vena cava electrode and ring and tip electrodes intended to be placed in the ventricle. A sense amplifier is connected across the ring and tip electrode, and the cardioversion energy is delivered across the superior vena cava electrode and the ventricular electrodes. A circuit for protecting the low voltage sense amplifier circuits from high voltage cardioversion output pulses includes a triac which is electrically shorted across the ring and tip electrodes and the input terminals of the sense amplifier during the delivery of the stimulating pulse.

Abstract: Real time analog and digital information are simultaneously transmitted from a transmitter circuit. In the disclosed embodiment, the analog signals are obtained from ECG apparatus and the digital signals are derived by a process or from analysis of the ECG signals. The system is implemented by summing the output signals from the FM oscillator and the FSK oscillator in an amplitude summing amplifier and transmitting the result in combined waveform, preferably over a phone line, although radio transmission may alternately be used as well as other types of transmission of the resulting signal.In the present invention, the analog signal is employed to frequency modulate a frequency modulated oscillator, and the digital information signal is used to obtain frequency shift keying of a FSK oscillator.

Abstract: Novel, hydrophilic, skin-compatible, pressure sensitive, solid, adhesive gel hydrogel composition comprising 25 to 50 weight percent polyvinyl pyrolidone (PVP) preferably having a molecular weight in the range of about 100,000 to 600,000, 2 to 5 weight percent polyvinyl alcohol (PVA) preferably having a molecular weight in the range of about 150,000 to 300,000, about 5 to about 40 weight percent humectant, about 3 to about 50 weight percent water, about 0 to about 50 weight percent of an ionic species. In a preferred aspect, the composition of the invention is utilized in an iontophoresis device to provide a hydrophilic gel matrix from which a drug is iontophoretically delivered.

Abstract: A self-adapting demand pacemaker that recognizes the tachycardia from the intrinsic signals and initiates treatment in the following manner: First, the escape interval of the demand pacemaker is shortened to be identical to the cycle length of the tachycardia, then to overdrive the tachycardia the pacemaker escape interval is continuously shortened with each subsequent beat, for a predetermined number of beats, by a small programmable decrement. Thereafter, the escape interval is restored to its original value and protects against a potential bradycardia. It has to be emphasized that the pacemaker remains in demand mode all of the time; thus stimulation in a vulnerable zone is prevented and some of the hazards that accompany overdrive pacing are reduced.

Abstract: A body implantable lead for the delivery of stimulation energy to a desired body site including a drug dispenser carried by the lead which retains a drug to be dispensed while allowing the dispensing of that drug at least adjacent the desired body stimulation site. The drug is retained in a cavity within the lead, in the form of a solid plug or a powder wherein the drug is compounded with an appropriate molecular sieve material. The drug is released only after the molecular sieves are activated by exposure to water. In those embodiments in which the molecular sieves take the form of a powder, the molecular sieves and drug may be conveniently loaded into the electrode, after manufacture and prior to implant.

Abstract: An in-line connector assembly for use with electrode leads employing plural, coaxial, coiled conductors. The connector assembly includes a connector ring, a connector pin, and an insulating sleeve separating the connector ring and connector pin. The insulating sleeve is molded to the connector ring and connector pin, prior to attachment to the proximal end of a multiconductor lead.

Abstract: A dual channel neuromuscular stimulator. Pulses developed by a pulse generator are transmitted alternately on both channels to involuntarily contract muscles. The stimulator has variable on/off cycling capability to provide flexibility in meeting the stimulation needs of patients and has output current adjustments and other variable parameter settings to achieve optimum neuromuscular stimulation. To enhance patient comfort, the stimulation output of the stimulator can be slowly "ramped up" to its full stimulation power to allow the increase in stimulation to occur at various rates to accommodate the differing characteristics of different muscle groups. A jack is provided to permit the stimulation to be controlled by an external switch operated by a clinician to coordinate stimulation of various muscle groups with voluntary muscle contraction by the patient. The jack can also be connected to a heel operated switch to stimulate muscle groups to allow certain disabled persons to walk normally.

Abstract: An iontrophoretic medical device has a first light of controlled brightness. Iontophoretic contact with skin is measured by current flow and a second light is illuminated in proportion to current flow. Generally, equivalent brightness of the two lights indicates successful iontophoretic contact.

Abstract: A body implantable lead having a two-piece stylet. An inner solid portion of the stylet enables a shape to be imparted to the stylet to allow proper maneuvering of the lead during implant. A second portion of the stylet is slideably located coaxially about the first portion. The second portion of the stylet permits the imposition of a torque at the distal end of the implantable lead by the turning of a knob fixedly attached to the proximal end of the second portion of the stylet. The second portion of the stylet is a helically wound coil. The two-piece stylet is inserted into the proximal end of the body implantable lead. The distal end of the body implantable lead is located in the position desired through the use of the solid inner first portion of the stylet in which a bend or other desired shape has been introduced. The body implantable lead is permanently attached to the muscle tissue by a fixation device activated through the torque supplied by the second portion of the stylet.

Abstract: An implantable fluid dispensing device has an accessory housing set into the biocompatible shape of its device canister. A shelf is set into the canister to accept the accessory housing which contains a filter, an externally accessible infusion septum, or other accessory. The function of accessories in the accessory housing is independently tested. After an accessory is selected to match the particular application, the accessory module is mounted on the canister.