Abstract: A transvenous pacing lead suitable for chronic implantation having structure which permits dispensing of drugs or other chemical agents from the ring tip electrode upon physician discretion from implant through chronic implantation. A bipolar, tined endocardial ventricular lead has a plurality of small apertures within the ring tip electrode which are connected by a tube within the lead body to a bladder at the proximal end of the lead. The bladder is detachable to permit a stylet to be passed through the tube to guide the lead during implantation. A reed valve at the distal end of the tube prevents body fluid from entering the tube. A stylet restraint prevents the stylet from damaging the reed valve during implant.

Abstract: Epicardial pacing lead for affixation to epicardial heart tissue either onto the forward facing portion of the heart or behind the heart during thoracic surgery. A stylet controls a helical fixation screw in an electrode head of the pacing lead in that the stylet is turned thereby advancing the helical fixation screw beyond the planar surface of the electrode head. The epicardial pacing lead includes two embodiments which can be used in the unipolar mode of operation and one embodiment which can be used in the bipolar or unipolar mode of operation. The epicardial pacing lead requires no special tools and can be applied to the epicardial tissue with the use of surgical forceps or clamps. The pacing lead can be connected to a pulse generator located adjacent to the epicardial tissue under the skin and can be used for atrial or ventricular pacing.

Abstract: A lead having multiple electrodes which is transvenously implanted for use in standby defibrillation of patients having a high risk of ventricular fibrillation. The lead employs four electrodes. The two distal electrodes have a spacing for optimal measurement of impedance changes due to mechanical contractions. This impedance measurement is used for mechanical sensing of normal cardiac activity. The electrode at the very distal tip terminates in a hemispherical shape. Two proximal electrodes are closely spaced and located at a distance from the two distal electrodes which ensures their placement within the superior vena cava whenever the distal electrodes are placed within the right ventricular apex. The body of the lead uses drawn brazed strand conductors wound triaxially for maximum flexibility, minimum cross-sectional area and the required high current carrying capability. At the proximal end of the lead, three connectors are used to electrically couple the lead to an implantable pulse generator.

Abstract: An electrode for a body implantable lead having a semiconductor surface for the coupling of electrical signals to the body tissue. A first approach uses several materials of differing conductivities. These materials are arranged in layers such that the material having the lowest conductivity is in direct contact with body tissue. The layers are then added in increasing order of conductivity. The intersection of two materials may be abrupt or may be a smooth transition fashioned by a combination of the two materials. The second approach provides an abrupt transition from the highly conductive materials within the lead body to a semiconductor material having direct exposure to the body tissue. The conductor within the body implantable lead is preferably fabricated using drawn brazed strand coils arranged in multifilar fashion. The conductor coils are insulated using a polyurethane sheath.

Abstract: A temporary lead for pacing or monitoring purposes with insertion tool. The temporary lead is thin and lightweight having an electrical connector at a proximal end and an electrode at a distal end. A length of surgical thread is permanently attached to the electrode. A helix is molded into the surgical thread at a short distance from the electrode. A curved needle is permanently attached to the surgical thread. The curved needle is inserted into a first location of the tissue manually or using the disclosed tool which provides insertion at a fixed depth. The curved needle exits the tissue at a second location. The curved needle and surgical thread are pulled from the second location thus bringing the electrode into sufficient contact with the tissue. The helix is elongated under the stress of tension supplied to pull the electrode into position. The excess surgical thread is cut at the second location, removing the tension.

Abstract: An electrode system for recording neural signals suitable for chronic implantation employing shielding and other techniques to improve signal-to-noise ratio. Three electrically isolated electrodes are used in a tripolar fashion. The electrodes are thin wires which are coated with a conductive gel. Each electrode is wrapped around the nerve trunk and held in place by a dielectric encapsulant. A shielding flap is wrapped about the assembly. The electrodes are coupled to conductors that travel through a shielded tube to the sensing electronics. The shield of the tube is electrically coupled to the shielding flap.

Abstract: A synthetic leaflet aortic and mitral heart valve for use in replacement of diseased natural heart valves having a flexible, curved framework, a flexible membrane attached to the framework and fixation means for attaching the valve to the tissue annulus. The framework consists of at least three curved flexible valve struts, each joined together at one end to a common central point of the valve and extending in the same direction radially at equal angles so that the free ends are unattached and at a distance from one another. The free ends are provided with sewing pads for artificial attachment of each free end separately to the natural tissue annulus or to an artificial annulus reconstruction ring which itself is sutured to the tissue annulus to restore its symmetry.

Abstract: A lead or heart wire for use in temporary electrical stimulation or monitoring of epicardial tissue. Positive fixation is accomplished by suturing the electrode to the tissue using an attached length of surgical thread and a curved needle. The heart wire is a tightly wound helix of wire insulated by a sheath. A needle, used for electrical connection to external equipment, is attached to the proximal end. Near the distal end, the conductor is bent into an "C" shape. The electrode is attached about midway along the top of the "C" shaped length of conductor. The length of surgical thread is attached to the proximal end of the conductor and exits the sheath through an aperture proximal to the "C" shape. The curved needle is attached to the distal end of the surgical thread. The heart wire may be readily removed after use by removing the surgical thread. The heart wire may be readily removed after use by removing the surgical thread, which is retracted into the conductor by pulling at its proximal end.

Abstract: A physiological event detector including apparatus for receiving and detecting an electrical signal corresponding to a physiological event. The apparatus produces a logic level output when the input signal meets both passband energy criteria and time duration criteria. The structure of the invention includes a filter for selecting the passband criteria and digital timing circuitry for determining how long the passband signal exceeds a minimum energy threshold.

Abstract: A pacer having an upper and lower rate limit system for preventing pacer malfunction from producing pacer output pulses above or below preset maximum and minimum rates.

Abstract: Ring electrode for a bipolar pacing lead where the ring electrode is secured to an outer coiled conductor by swaging the outer coiled conductor between the ring electrode and a swaging core where the distal end of the outer coiled conductor positions over the swaging core and into the ring electrode. The outer coiled conductor is mechanically swaged between the ring electrode and the swaging core resulting in a mechanical and electrical joint. Insulation extends over the outer ends of the ring electrode and yields a bond to the ring electrode having substantially the same outer diameter as the ring electrode.

Abstract: Memory control circuitry for use in a pacemaker or other medical device for setting volatile memory to a known configuration if the battery voltage and/or current drops below the level required for reliable operation of the memory devices.

Abstract: Pacing lead including an elasticized snap-on sleeve integral with a fixation pad for covering and protecting a tip of an electrode, and which is designed for either ventricular or atrial pacing. The electrode includes a U-shaped mid-portion, and extends into and across a hole in the fixation pad. The bottom of the U-shaped portion is recessed slightly below the hole to a position slightly below the lower surface of the elasticized fixation pad. The pacing lead is intended for permanent epicardial pacing, includes a one piece design, provides for easy insertion, is acutely removable, is intended for long-term fixation and acute fixation, and has a low profile suitable for either ventricular or atrial pacing.

Abstract: Heart valve including an annular valve body having an inner wall defining a blood flow passage, a guide strut including an integral pivot surface extending radially inward of the valve body and a disc occluder having a central aperture engaged over the disc guide strut, a disc stop extending radially inward of the valve body opposite the guide strut, and pivot projections extending radially inward of the valve body and equally spaced from the guide strut whereby the disc pivots between occluding and non-occluding surfaces in response to downstream blood pressure gradients across the disc.

Abstract: Transvenous leads including an outer atrial and an inner ventricular spaced wound coils coaxial with respect to each other and including a closed fixation loop connected to the outer lead. The closed fixation loop extends outwardly at an angle with respect to the outer lead. An inner lead is slideably adjustable within the outer lead and supports a ventricular electrode. The outer lead supports an atrial electrode. A connector at the other end of the leads supports and secures a connector pin for the outer lead in one sleeve and provides for slideable adjustment of the inner lead which includes a proximal tip in the other sleeve. An O-ring engages in an O-ring groove in the other sleeve to provide a liquid seal between the atrial coil and the end of the ventricular coil. The proximal tip and connector pin connect to a pulse generator. The transvenous leads with the closed fixation loop are intended for pacing the ventricular and atrial chambers of a heart.

Abstract: Myocardial sutureless unipolar lead including an insulated conductor coil adjacent to a base pad, and a barbed electrode spaced adjacent to the base pad and connected to the conductor coil. The sutureless myocardial unipolar lead requires no stab wound or sutures for electrode placement and support. The barbed electrode is secured to the heart by gently pushing the tip into the myocardial tissue and the electrode is thereby secured to the myocardial tissue. The lead accepts a stiffening stylet for controlling the stiffness to aid in placement of the electrode within the myocardial tissue, and without the need for further insertion tool. The angle of the barbed electrode determines the specific application of the lead for ventricular or atrial pacing applications.

Abstract: A CMOS inverter is used to compare pacemaker battery voltage to a referenced voltage. When the reference voltage exceeds the measured battery voltage, the inverter changes state to indicate battery depletion.

Abstract: A dual pace--dual sense cardiac pacemaker pulse generator having ventricular and atrial sensing and pulse generating means interconnected by circuit means to cause the atrium to be stimulated in the event that a natural atrial contraction is not sensed within a certain time from the last ventricular stimulus or natural contraction and the ventricle to be stimulated in the event that a naturally ventricular contraction is not sensed within a further time from the last atrial contraction or stimulus.

Abstract: A screw-in endocardial transvenous pacing lead having a lead tip with a sealing membrane. The lead is chronically affixed by a helical fixation coil having a pointed tip which is rotatably advanced through a helical lumen in the lead tip into the endocardial tissue. During transvenous insertion, the helical fixation coil is retracted into a chamber to protect against damage of the vein. A sealing membrane is positioned perpendicularly within the helical lumen of the lead tip preventing ingress of body fluids. The sealing membrane is of silicon rubber with a polyurethane coating on either side. Upon being properly located within the heart, the helical fixation coil is rotatably extended. The pointed tip of the helical fixation coil punctures the sealing membrane normal to its direction of travel. The sealing membrane provides a seal around the helical fixation coil.

Abstract: Passive sensing reference electrode positioned on an implantable pulse generator where the electrode electrically contacts with tissue or body fluid. The electrode configuration reduces stimulation afterpotentials due to electrode polarization and output capacitor recharge by using the passive sensing reference electrode for sensing. The passive sensing reference electrode may be located adjacent the conductor sleeve, on a surface of a hermetically sealed metallic pacemaker can, or one of the surfaces of the pacemaker can may be insulated from another surface of the pacemaker can where one half of the pacemaker can may be the passive sensing reference electrode.