Abstract: A self-sealing, penetrable, hemostasis valve for a catheter introducer or the like which comprises an elastomeric gasket member having first and second opposed faces adapted to be secured in a valve housing, wherein faces define generally concave surfaces to reduce the central thickness of the gasket member, and a pin hole or slits extending through the first and second opposed faces generally at or through the central region of the gasket member. The generally concave opposed face surfaces are molded to possess a pair of convex cusp-shaped surfaces, each lying in about one-half of the generally concave surfaces, each convex cusp having an edge thereof passing generally through the central region of reduced thickness. The pair of generally convex, cusp-shaped surfaces on the first face is disposed at a 90 degree angle to the pair of generally convex, cusp-shaped surfaces on the second face.

Abstract: An audio frequency amplification circuit for use with low level, high impedance signal sources, such as a miniature electret microphone, particularly useful where the power supply range is variable or may be limited to a single cell. The preferred embodiments of the circuit include a field effect transistor preamplifier stage operating as a voltage follower which is biased by a first and second impedance network coupled to the gate electrode of the FET transistor. A first impedance network is coupled between the power source terminals to provide a floating bias point. A second, high impedance network comprising (in one embodiment) a pair of parallel, reverse oriented diodes and a high impedance resistor is coupled between the bias point and the gate terminal of the transistor. In a further embodiment, the first impedance network comprises series connected high impedance resistors, and the second impedance network includes only the parallel, reverse oriented diodes.

Abstract: A device to be used as a vascular stent comprising a cylindrical open-ended wire component made of a low memory metal such as copper alloy, titanium, or gold, providing a radial support from within a blood vessel after implantation therein. The coronary stent is characterized by its ability to be expanded radially to a larger diameter after initial implantation and means for causing said stent to expand to a larger diameter and a method for transporting, positioning and implantation of such coronary stent transluminally to have said stent act as a permanent prosthesis to assure vascular patency. And method for simultaneous angipolasty and stent implant procedure.

Abstract: A rate responsive pacer is disclosed which alters the pacer's escape interval in response to the patient's metabolic demand. Metabolic demand is determined from the patient's respiration rate which is extracted from spontaneous muscle signals.

Abstract: A method of terminating ventricular fibrillation by the delivery of an asymmetric biphasic current pulse to three separate electrodes. A first catheter mounted electrode is located in the apex of the right ventricle (RV). A second electrode carried on the same catheter is located outside the atrium preferably in the superior vena cava (SV). A third plate electrode is located subcutaneously outside the chest cavity. Preferably, the SVC electrode and the subcutaneous plate electrode are electrically interconnected and an asymmetrical biphasic current pulse is applied between this electrode pair and the RV electrode to defibrillate the heart.

Abstract: A cardiac pacing lead or other stimulation lead carrying a drug incorporated into a controlled release device. The lead is provided with an extendable fixation helix which is advanceable from the distal end of the lead in order to engage with the tissue to be stimulated and to maintain the distal end of the lead adjacent the tissue to be stimulated. The controlled release device is located within the fixation helix and is extended with the fixation helix when it is advanced out of the distal end of the lead. In its advanced position, the controlled release device is positioned adjacent the distal end of the lead, preferably in a position to contact the tissue to be stimulated.

Abstract: An activity responsive, rate adaptive pacer, which senses and paces in both the atrium and ventricle is disclosed. The pacing rate displayed by the pacer is determined by the sensed activity of the patient, the programmed lower rate, and the patient's atrial or sinus rate.

Abstract: A connector for use in conjunction with implantable, medical electrical leads, such as cardiac pacing leads. The connector is of the type known in the pacing industry as "in-line", and includes an elongated connector pin and a cylindrical connector ring, spaced longitudinally from one another, and separated by an insulative segment. The connector pin is adapted to rotate within the connector, in order to transmit torque down the body of the electrical lead to activate a fixation device or other apparatus. Surrounding the connector pin is an elongated bearing sleeve which engages an elongated, reduced diameter segment of the connector pin. The connector pin is provided with circumferential shoulders at the proximal and distal ends of the reduced diameter portion of the pin, which in turn engage the bearing sleeve.

Abstract: A medical electrical lead having a polyurethane outer sheath and one or more coiled metal conductors. The metal conductors are optimized for use in conjunction with a polyurethane sheath and are provided with a barrier coating of a biocompatible metal. The conductors may additionally be provided with an outer, insulative coating.

Abstract: A cardiac pacing lead has a plurality of individually insulated conductors arranged as a multifilar coil. The lead includes a connector assembly and a ring electrode assembly, each of which are optimized for use in conjunction with conductors arranged in the form of a multifilar coil. The connector assembly takes the form of an in-line connector having a plurality of linearly arranged connecting surfaces, each coupled to one of the conductors in the multifilar coil. The ring electrode assembly is constructed such that it displays the same outer diameter as the pacing lead. In both assemblies, conductors are coupled by means of welds, rather than by crimping or swaging.

Abstract: A cardiac pacemaker which generates stimulus pulses and senses the occurrence of natural heartbeats in a patient. The pacemaker provides for a mode of pacing rate control which tracks naturally conducted heartbeats, and responds to premature ventricular contractions. The escape interval of the pacemaker, after either a paced beat or a natural contraction, is determined by the immediately preceding escape interval, and increases with each heartbeat cycle until a predetermined lower rate is reached.

Abstract: A process for producing a medical electrode. A coil of conductive metal is slid over a tubular insulative substrate. The spaces between individual turns of the coil are backfilled with an insulative plastic. The backfilled plastic is thereafter etched away from and off of the exterior of the metal coil by means of a gas plasma.

Abstract: A mechanical heart valve prosthesis has an annular base which defines a passageway for blood flow, and a pair of valve leaflets hingedly mounted within the annular base for regulating direction of the blood flow. The hinge mechanism includes camming indentations or hinge cavities located substantially in the corners of the valve leaflets at least on one side of each leaflet, and a plurality of camming or hinge pins which protrude radially inwardly from the annular base to engage both sides of the leaflets. Each of the hinge cavities is engaged by one hinge pin. During operation, the valve leaflets undergo certain wobbling or walking motion relative to the hinge pins whereby the hinged surfaces are continuously wiped to minimize the possibility for formation of incipient blood clots.

Abstract: A connector system for use in coupling an implantable electrical lead to an implantable pulse generator, or other implantable electrical apparatus. The connector system includes a connector pin assembly, typically mounted to the implantable lead and a connector block, typically mounted to the electrical stimulator. The connector block is provided with a lumen, in which a plurality of resilient, elastomeric rings are linearly arranged. The rings are so sized as to frictionally engage a connector pin which is provided with a plurality of conductive pads, each coupled to a conductor within the implantable lead. Certain ones of the elastomeric rings are conductive, and engage with the conductive pads on the connector pin. Others of the rings are nonconductive and act as insulators and fluid seals. The connector pin assembly is also provided with a circumferential groove, which interlocks with the deflectable beam members of a retainer mounted to the connector block.

Abstract: A pacemaker which operates in an atrial synchronized modality when the sensed atrial rate is within a physiologic range and which paces at a sensor determined rate when the atrial rate is above or below the physiologic range.

Abstract: An endocardial defibrillation electrode system as provided, including a coronary sinus lead, a ventricular lead, and a subcutaneous plate. The coronary sinus lead includes an elongated electrode adapted for location in the coronary sinus, extending into the great vein, and termination in the vicinity of the left atrial appendage. The right ventricular eletrode may be located either in the right ventricular apex, or may extend from the right ventricular apex to the vicinity of the tricuspid valve. This subcutaneous electrode preferably is a large surface electrode, adapted for implant in the vicinity of the heart. A variety of defibrillation pulse regimes are disclosed, optimized for use with the defibrillation electrode system, and with subgroupings of the disclosed electrodes.

Abstract: A cardiac pacing lead having a plurality of individually insulated conductors arranged as a multifilar coil. The lead includes a connector assembly and a ring electrode assembly, each of which are optimized for use in conjunction with conductors arranged in the form of a multifilar coil. The connector assembly takes the form of an in-line connector having a plurality of linearly arranged connecting surfaces, each coupled to one of the conductors in the multifilar coil. The ring electrode assembly is constructed such that it displays the same outer diameter as the pacing lead. In both assemblies, conductors are coupled by means of welds, rather than by crimping or swaging.

Abstract: A dual chamber pacemaker having an atrial escape interval which is varied on a beat-to-beat basis in response to the measured time from a ventricular event to the next atrial sensed event. Additionally, a portion of the atrial escape interval is bifurcated into a first sensing portion T1 and a second sensing portion T2 wherein atrial sense events occurring during T1 may be ignored by the pacemaker, while atrial sense events falling within T2 are used to compute a new atrial escape interval and are used to resynchronize the pacemaker and are used to inhibit the otherwise scheduled atrial pace event.

Abstract: A demand pacemaker which regulates its pacing rate based upon sensed oxygen saturation percentage. The pacemaker employs a two wavelength reflectance oximeter as a sensor. The sensor includes an oscillator which sequentially activates red and infrared diodes. The duty cycle of the oscillator is regulated by the relative amounts of red and infrared light reflected by the blood. The construction of the sensor allows the sensor to operate with only two conductors, optimizing it for incorporation in a standard, bipolar pacing lead.

Abstract: A connector system for use in coupling an implantable electrical lead to an implantable pulse generator, or other implantable electrical apparatus. The connector system includes a connector pin assembly, typically mounted to the implantable lead and a connector block, typically mounted to the electrical stimulator. The connector block is provided with a lumen, in which a plurality of resilient, elastomeric rings are lineraly arranged. the rings are so sized as to frictionally engage a connector pin which is provided with a plurality of conductive pads, each coupled to a conductor within the implantable lead. Certain ones of the elastomeric rings are conductive, and engage with the conductive pads on the connector pin. Others of the rings are nonconductive and act as insulators and fluid seals. The connector pin assembly is also provided with a circumferential groove, which interlocks with the deflectable beam members of a retainer mounted to the connector block.