Abstract: A single pass atrial-ventricular transvenous pacing lead wherein the atrial branch has a positive fixation device. The proximal end of the lead has a standard electrical connector for coupling both atrial and ventricular electrodes to an implantable pulse generator. The lead is bifurcated at a point near or above the superior vena cava during normal transvenous insertion. The atrial and ventricular branches are of a fixed length from the point of bifurcation to the distal tip. The ventricular branch preferably employs a passive fixation device such as tines to maintain the ventricular electrode within the right ventricular apex. The atrial branch is positioned in the normal manner under control of a stylet to obtain optimal sensing and stimulation thresholds. This position is maintained using an active fixation device. Preferably the active fixation device is a helix which is screwed into the atrial wall by rotating the atrial connector pin and conductor coil.

Abstract: Technique for permitting ease of mapping of the myocardial tissues during implantation of a myocardial electrode. The technique employs the use of a disposable exploring needle located on the distal end of the implantable lead assembly. The permanent electrode is attached to the exploring needle by being embedded into an electrically conducting material of the exploring needle. The implanting physician explores the electrical characteristics of the myocardial tissues using the exploring needle. Upon finding the desired electrode location, the exploring needle is removed and discarded and the electrode is permanently attached in the manner customary in the prior art.

Abstract: A programmable pacemaker pulse generator capable of operating in several atrial and ventricular pacing modes, having atrial and ventricular sense amplifiers and output circuits and programmable memory and clock controlled digital timing circuits for selectively delivering stimulating pulses to the heart in an atrial synchronous mode of operation. The ventricular sense amplifier has a blanking and refractory period following the sensing of a ventricular heartbeat or the occurrence of a stimulation pulse. Delay means are operatively connected to the atrial sense amplifier operate to trigger the generation of a ventricular stimulating pulse after an A-V delay interval following a sensed atrial depolarization.An atrial blanking interval extends for the A-V delay interval and until after the expiration of the ventricular blanking interval. Programmable upper date intervals are also provided.

Abstract: A dual chamber pacing lead requiring but a single transvenous pass for implantation. The ventricular electrode has tines for sustaining acute and chronic fixation. The ventricular electrode is coupled to a first conductor which is space wound having an insulation sheath. The proximal end of the first space wound coil protrudes slideably from a first connector pin of a bifurcated connector assembly. An optional stylet may be inserted into the first space wound coil to assist in ventricular placement. A second space wound coil is slideably located over the first space wound coil. The second space wound coil serves as a support means rather than a conductor. The proximal end of the second space wound coil is fixedly attached to the connector assembly. The first space wound coil protrudes near the distal end of the second space wound coil.

Abstract: A programmable pulse generator capable of operating in several atrial and ventricular pacing modes having atrial and ventricular sense amplifiers and output circuits, programmable memory and clock controlled digital timing circuits and a depletable power source. End-of-life sensing circuits detect first and second end-of-life depletion levels. Magnet activated end-of-life test circuitry responds to the presense of none, one or both of the end-of-life depletion level signals to alter the operating modes and pacing rates to indicate the orginally programmed mode and the level of depletion to an observer. Preferably, the pulse generator is operated in the asynchronous DOO or VOO modes and at non-programmed test rates to provide the indication.

Abstract: A service kit for splicing body implantable leads having inner and outer coaxially-arranged coil wire conductors insulated from one another. A conductive pin having a distal portion with an outside diameter less than the inside diameter of the inner coil has a barbed tip that is screwed into the inner conductor coil. A shoulder portion of the conductive pin having a larger diameter bears against and retracts the inner coil with respect to the outer coil as the distal portion is screwed into the coil lumen. An insulating sleeve over the shoulder portion assures that the conductive pin does not contact the outer conductor coil. An adaptor housing physically holds the end of the coaxial lead being spliced, the conductive pin and the insulating sleeve. A first set screw through the adapter housing contacts the conductive pin allowing electrical contact thereto.

Abstract: A gamma ray scintillation camera generating (X,Y) spatial coordinate and Z energy signals relative to detected radiation events. The system provides for calibration of the camera Z signal response as a function of camera face location. In addition, the camera signals are converted to their digital equivalents subsequent to which the apparent coordinate locations of detected events as determined by the camera are corrected to their true spatial coordinates based upon correction information stored in the system.

Abstract: An implantable medical device to deliver cardioverting energy to cardiac tissue in synchrony with detected ventricular depolarizations. The energy renders refractory, areas of the heart associated with a reciprocating or automatic tachycardia, thus reverting these tachyarrhythmias to normal sinus rhythm without the risk of stimulating the heart during the vulnerable portion of repolarization.

Abstract: A structure for use as an electrode on a pacing lead to be located some distance proximal to the distal end of the pacing lead. Two short lengths of wire having high electrical conductivity are cut to size. The coils of the outer conductor are welded together at the desired location of the ring electrode of the lead. The two short lengths of wire are welded to the outer conductor of the lead at the desired location of the ring electrode. An insulating sheath having an inside diameter close to the outside diameter of the outer conductor is slid over the outer conductor. The flexibility of the insulating sheath is sufficient to permit encasing of the two short lengths of wire, though the insulating sheath is caused to protrude at the two places directly over and corresponding to the two short lengths of wire.

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: A demand cardiac pacemaker of the type having sense amplifier circuitry for detecting the occurrence of natural heart activity which establishes a first level representative of sensed extraneous repetitive noise and a second level greater in absolute value than the reference by an amount representative of sensed heart activity. Circuitry differentially responsive to the difference between the reference and second level detects the occurrence of natural heart activity. The sense amplifier circuitry is blanked, that is disconnected from the terminals coupled to the heart, for a blanking interval following stimulation to avoid saturation of the sense amplifier stages and the erroneous detection of a pacing stimulus. Any reference level voltages developed by extraneous repetitive noise are retained during blanking to prevent the differential circuitry from interpreting the noise signal sensed at the end of the blanking interval as a heart signal.

Abstract: A marker channel telemetry system for use with a pacemaker or other medical device for transmitting event identifying codes to a remote receiver to indicate the occurrence of specific events such as sensed and paced events in a dual chamber pacemaker. The structure of the system includes latches to store event information and for forming the marker codes. The system also includes a serial telemetry transmitter for transmitting the data to the remote receiver.

Abstract: Apparatus for monitoring and storing electrical signals indicative of a patient's heart activity is disclosed as including a memory comprising a first plurality of storage locations for receiving a series of the patient's heart signal and a second plurality of storage locations. Further, there is included a circuit for accessing or examining the heart signals stored in the first plurality of locations to determine their duration and amplitude and a further circuit for comparing the determined amplitude and duration with given criteria and, if met, for storing the evaluated heart signals in locations of said second plurality in a compacted manner adapted to be read out. More specifically, the comparing circuit compares the amplitudes of signals in adjacent locations of said first plurality to determine their difference and, if greater than a given threshold value, to determine the existence of a valid peak of the patient's heart signals, i.e., his heartbeat.

Abstract: A digital computer system is described as comprising an input data circuit, a processor for executing a program stored in a memory to process the inputted data, a depletable energy source (e.g., a battery) for energizing the elements of the computer system, and a power control circuit for selectively controlling the drain imposed upon the energy source in accordance with the data input into the system and the program executed by the processor. In an illustrative embodiment of this invention, the power control circuit is operative in at least three modes of operation, namely off/rest, power down, and operating. In the off/rest mode, the power control circuit imposes a minimum power drain upon the depletable energy source. An operator may manipulate a switch or actuation means to apply a transition signal to the power control, whereby the computer system is disposed from its off/rest mode to its power down mode.

Abstract: Apparatus is disclosed for monitoring and storing electrical signals in a manner to detect the intervals between heartbeats and to provide a manifestation of whether the corresponding heart signals have a regular heart rhythm or not. Such apparatus comprises a memory having at least first and second areas, a circuit for receiving and sampling the heart signals, and a circuit for temporarily storing the heart sample signals in the first area. Further, there is included a circuit for processing or evaluating the heart signals stored in the first area to determine the occurrences of the patient's heartbeat and for determining the intervals between adjacent heartbeats. The determined intervals are stored in the second area and are evaluated to determine whether the patient's heart activity occurs with a regular rhythm. The monitoring and storing apparatus is operative over a monitoring period comprised of a plurality of trend sample intervals.

Abstract: Apparatus and method for accurately measuring the energy output of a pacing system analyzer or other pulse generator. Voltage measurements are made across the output capacitor before and after the pulse is generated. These voltages are measured by a microprocessor using an analog-to-digital converter and various gating and control circuitry. By using a known value of capacitance for the output capacitor along with the voltages measured before and after the stimulation pulse is generated, the microprocessor can calculate the total amount of energy within the stimulation pulse. This value is displayed on an integral display device. Through the use of additional circuitry, measurements may be made for both atrial and ventricular stimulation pulses in a dual chamber stimulation device. Provisions have also been made for measuring the output energy for constant voltage pulse generators. This technique employs measurement of pulse width.

Abstract: A multiple-mode pacer which automatically switches from an atrial synchronous mode to a ventricular inhibited mode when the intrinsic atrial rate drops below a preset hysteresis rate. This mode switching prevents atrial bradycardia from resulting in the delivery of closely spaced ventricular stimulating pulses.

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: Heart monitoring and storing apparatus is disclosed for evaluating heart activity signals to determine if valid, for identifying a characteristic of the valid heart activity signal, and for storing the signal into a corresponding location of a memory depending upon the characteristic of the heart activity signal. Such apparatus comprises the memory including a first area and a second area, and a circuit for sampling the heart activity signals and for storing the heart signal samples into corresponding locations of such first area. There is further included an evaluation circuit for determining whether the sampled heart activity signals as stored within the first area are valid and particularly if they indicate the occurrence of a heartbeat. An addressing circuit is provided for determining the various characteristics of a valid heart signal and for selectively addressing a location within said second area to store the valid heart signal of the corresponding characteristic.

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.