Abstract: A joint assembly which may be used for affixing a helically wound lead conductor coil to an electrode of a pacemaker. The electrode has a longitudinal bore and a coaxial counterbore. One end of the coil is fittingly attached to a reduced diameter end of a press tube. The outer diameter of the extreme outer surface of the coil on the press tube is slightly greater than the inner diameter of the counterbore in the electrode. The reduced diameter end of the press tube with the coil thereon is fittingly inserted into the counterbore. This results in a solid connection between the lead conductor coil and the electrode without causing any visible alteration of the outer surface of the electrode.

Abstract: A multi-part molded pacemaker connector meets the precise requirements imposed by the VS-1 standard, yet does not require complex nor expensive machining of individual parts. The connector includes a molded body tip and a molded body ring, adapted to be joined together during assembly. The body tip is molded to include a conductive connector block attached to a first conductive ribbon as an integral part thereof. The body ring is molded to include a second conductive ribbon, having a looped end exposed therewithin to provide a precise specified diameter against which a garter spring contact is placed. An inner shoulder molded within the body ring holds the spring contact laterally on one side. During assembly, an annular spacer is pressed into the body ring to restrain the spring contact laterally on the other side. Inner and outer annular seals are also inserted into the body tip and body ring during assembly. After assembly, i.e.

Abstract: A motion sensor for use within an implantable medical device provides a digital output signal that can be connected directly to the digital processing and control circuits of a pacemaker or other device. This signal may be used to adjust the basic pacing rate of the pacemaker as a function of the physical motion or activity that is sensed. The motion sensor includes an enclosed housing having conductive element therein that partially fills the space of a cavity within the enclosed housing. The conductive element is free to roll, flow or otherwise move around the inside of the housing in response to external forces. The external forces that cause the conductive element to move include the physical motion of the patient as well as the force of gravity. As the conductive element moves within the enclosed housing, it makes electrical contact with at least two of three electrodes that are selectively spaced around the inside periphery of the housing.

Abstract: A noise discrimination circuit determines if sensed electrocardiographic (ECG) pulsed signals sensed within a pulse generator are valid ECG signals, i.e., valid P-waves or R-waves, or noise. The ECG signal may then be processed. The processed ECG signal is monitored to determine both the amplitude and duration of any signal pulses appearing thereon. If the amplitude of a given ECG signal pulse exceeds a prescribed threshold level for a prescribed time period, the pulse is considered to be a valid ECG signal. The noise discrimination circuit includes: a threshold detector for determining if the amplitude of the ECG signal exceeds the prescribed threshold level; a timer circuit for generating a timed window signal, triggered by the threshold detector whenever the ECG signal amplitude exceeds the prescribed threshold level; and logic circuitry for determining if the amplitude of the ECG signal remains above the threshold level for the duration of the timed window signal.

Abstract: A device for use as an attachment for use with a main pump unit containing a prime mover and a control system for controlling the operation of a disposable cassette containing a fluid pump which is mounted on the main pump unit is disclosed which includes both a compartment for securely storing the medication supply and means for preventing either the cassette or the fluid line between the storage compartment and the cassette from being removed or tampered with. The device is locked onto the main pump unit with a single key operated lock which also locks the cassette in position on the main pump unit, the compartment for storing the medication supply, and a cover sealing the fluid line. The system is compact, and is capable of being used with a variety of fluid sources including both syringes and bags.

Abstract: A lead-to-pacemaker adapter allows the use of a smaller diameter lead connector than that for which the pacemaker was designed. The pacemaker is shipped with the adapter installed. If the adapter is not to be used, provision is made for its easy removal. The adapter is shown and described for use in a unipolar lead system. The adapter permits direct electrical connection from the terminal pin electrode to the pacemaker connector block and its terminal set screw without the interposition of any intermediate connecting elements.

Abstract: An air-in-line detection system for use in detecting air bubbles in the fluid line of a disposable cassette mounted on a main pump unit is disclosed which can accurately detect air bubbles in any type of fluid, whether clear or opaque. The system uses an optical module mounted on the main pump unit to supply light and to detect light returned from the cassette, and an optical viewing area in the fluid flow path near the outlet end of the cassette. An inverted prism in the optical viewing path reflects light back to the optical module when air is contained in the fluid flow path adjacent the optical viewing area, with the light not being returned if there are no air bubbles contained in the fluid flow path.

Abstract: An implantable pacemaker having a unipolar/bipolar lead interchangeability includes lead impedance measuring capability for automatically measuring lead impedance, initiated by the occurrence of predetermined events, such as whenever a programming change is made, whenever capture fails to occur in response to an applied stimulation pulse, whenever the leads are changed, and whenever a significant change of lead impedance is otherwise detected. If a proper impedance measurement is not sensed for a programmed configuration, additional impedance measurements for other possible configurations are made in an ordered sequence in order to determine if an improper lead has been implanted or if a electrode has broken. If an operable configuration is found, signified by a measurement of impedance as expected, the pacemaker continues operation in that configuration, thereby assuring that capture can continue to occur until such time as the problem which has been detected can be corrected.

Abstract: An ultrasonic air-in-line detection system for use in detecting air bubbles in the fluid line of a disposable cassette mounted on a main pump unit is disclosed which automatically loads the outlet tubing at the bottom of the cassette into a slot in an ultrasonic sensor housing when the cassette is installed on the main pump unit. The system uses a tubing adapter mounted on the outlet tube below the cassette, with the tubing adapter having a tapered top end. The tubing adapter interacts with a pair of ramps located on the bottom and front of the ultrasonic sensor housing around the slot to draw the tubing adapter into a recess located on the bottom of the ultrasonic sensor housing, thereby drawing the outlet tubing fully into the slot between an ultrasonic transmitter and an ultrasonic receiver in the ultrasonic sensor housing when the cassette is installed.

Abstract: A cardiac defibrillation system and method includes an epicardial electrode for making electrical contact with the epicardium from a position within the pericardial space, an endocardial electrode for making electrical contact with the endocardium of the heart, and means for making electrical contact with the epicardial and endocardial electrodes. The endocardial electrode is inserted transvenously into the heart in conventional manner. The epicardial electrode is also inserted transvenously into the heart, through the heart wall, and into the pericardial space. No open chest surgery is required.

Abstract: A method and system for positioning a defibrillation electrode within the pericardial space of a mammal is disclosed which includes means for distending the pericardium from the heart by injecting a small volume of fluid into the pericardium. A needle having a lumen therethrough is inserted from a sub-xiphoid or other percutaneous position into the body tissue until a tip thereof punctures the distended pericardium at a selected location. A guide wire is inserted into the pericardium through the lumen of the needle, and while the guide wire remains in the pericardial space, the needle is removed. A sheath is introduced over the guide wire, with the aid of a dilator, and inserted into the tissue until one end thereof is positioned within the pericardium.

Abstract: A method and system for positioning a defibrillation electrode about the heart includes means for placing the electrode in contact with epicardial or pericardial tissue from an inferior vena cava (IVC) access site. A small hole is made in the IVC at the selected access site. A defibrillation lead having the defibrillation electrode near its distal end is transvenously inserted through the IVC and out through the small hole into a chest cavity adjacent the heart. The electrode is then positioned so as to contact the desired cardiac tissue. If pericardial contact is to be made, the distal end of the lead, including the electrode, is looped around the pericardium. If epicardial contact is to be made, an additional small hole is made in the pericardium, and the distal end of the lead, including the electrode, is inserted through the additional hole into the pericardial space, and the electrode is positioned to contact the desired epicardial tissue.

Abstract: A pacemaker and a method of operation thereof are provided for configuring or operating a conventional pacemaker having a plurality of lead electrodes. Each lead can be independently configured for any combination of unipolar or bipolar, pacing and sensing. During a pacing mode of operation, a selected return electrode is switchably connected to the most positive battery potential, V.sub.DD. The return electrode of the packemaker, can selectively be either the pacemaker case or one or more ring electrodes. During a fast discharge time period, which occurs immediately subsequent to the delivery of a pacing pulse, the return electrode is disconnected from V.sub.DD and connected to the proximal side of a coupling capacitor through which the pacing pulse has passed. Also during this fast discharge time period, the proximal side of the coupling capacitor is switchable connected to the most negative battery potential, V.sub.SS.

Abstract: A non-programmable automatic implantable cardioverter/defibrillator (AICD) capable of providing programmable thresholds for triggering high energy stimulation pulse(s) from the AICD is coupled to an implantable programmable pacemaker which preferably includes bradycardia support and/or tachycardia support using low enery output pulses. When the low energy antitachycardia pulse(s) from the pacemaker fail to terminate a tachycardia, or whenever other various thresholds, as sensed by programmable sensing circuits of the pacemaker, are exceeded, the high enery pulses from the AICD may be selectively invoked by an AICD trigger circuit included within the pacemaker. Coupling between the AICD and pacemaker is by either a direct electrical connection, or by an indirect connection, such as through the use of narrow pulse sequences generated by the pacemaker which are of insufficient energy to invoke a cardiac response but are of sufficient energy to be sensed by the AICD sensing circuits.

Abstract: A communication system includes self-test means for automatically testing its performance. The communication system is adapted for use between an implantable device, such as a pacemaker, and an external device, such as the pacemaker's programmer. The communication system includes in the external device a transmitter circuit for transmitting an output signal through an antenna, and a receiver circuit for receiving an input signal through an antenna. A driver circuit controls the operation of the transmitter circuit. A microprocessor, connected to the driver circuit, controls the information content and timing of the transmitted output signal. A bandpass filter and AM demodulator process the input signal received through the receiver circuit. A multiplexer selectively allows one of a plurality of status signals from throughout the communication system within the external device, including the demodulated signal obtained from the AM demodulator, to be connected to the microprocessor.

Abstract: A self-oscillating burst mode transmitter transmits an integral number of cycles of a carrier signal in each transmission burst. Each burst commences at a peak value of the carrier signal and terminates at a peak value. The transmitter includes an L-C tank circuit comprising a transmitting coil (L1) connected to a capacitor (C4). The L-C tank circuit is selectively energized through a switching network (Q1, Q2, U1, U2) connected to a power source, causing the tank circuit to resonate at a prescribed frequency (f.sub.0). Selective energization of the tank circuit is achieved by the switching network as controlled by a peak voltage detection circuit (32, 34). The peak detection circuit senses when a peak voltage is present in the oscillatory waveform appearing across the coil of the resonating tank circuit. Power is switched off to the tank circuit at the conclusion of each transmission burst only when the oscillatory voltage waveform, as sensed by the peak detection circuit, is at a peak.

Abstract: An automatically adjustable blanking circuit and method of generating an adjustable blanking interval for use with a dual channel implantable pacemaker includes means for generating a basic blanking interval for a first channel of the pacemaker each time a stimulation pulse is generated on a second channel. The basic blanking interval includes a first absolute refractory portion and a second relative refractory portion. During the absolute refractory portion, the sensing circuits of the first channel are disabled. During the relative refractory portion, the sensing circuits of the first channel are enabled and any activity sensed in the first channel is considered to be crosstalk or noise and the basic blanking interval is retriggered. Retriggering of the basic blanking interval continues for so long as activity is sensed in the first channel during the relative refractory portion of each retriggered basic blanking interval, up to a maximum blanking interval.

Abstract: A device for use as a self-oscillating Class D transmitter is disclosed which uses feedback to maintain the oscillation at the resonant frequency of the device, thereby optimizing the efficiency of operation and overcoming the frequency mismatching inherent in previously known transmitters. The device uses a series LC combination which is driven by a comparator and a tri-state logic driver, with a feedback loop using a differentiator used to switch the polarity of the square wave generator. The system thus self-oscillates at the resonant frequency of the capacitor and inductor, even when the inductance of the inductor is varied by the inductor coming into close proximity to another inductor.

Abstract: A system for detecting an occlusion in a fluid line is disclosed which can detect occlusions in the upstream or container side of a disposable cassette containing a fluid pump therein. The cassette includes a piston-type pump with inlet and outlet valves, and is for installation onto and use with a main pump unit including motors for driving the pump and valves contained in each cassette. The system utilizes control circuitry to monitor the intake stroke of the pump in the cassette, to detect an upstream occlusion in the fluid line leading to the pump, and to provide an alarm in the event of a container-side occlusion.

Abstract: A method of significantly enhancing the period of time that an implanted intraperitoneal catheter used for the delivery of therapeutic medication will operate without encountering significant blockage by fibrotic tissue is disclosed. By monitoring and maintaining certain physical parameters in patients having an implantable catheter below desirable levels for the parameters, catheter survival in the patients is maximized. The four parameters used are blood triglyceride level, blood cholesterol level, the level of insulin dosage per day, and mean blood glucose (MBG) level, with the first two being the more accurate parameters.