Abstract: A defibrillation electrode for implantation on or about the heart and for connection to a defibrillation system. The electrode comprises a plurality of electrically conductive elements spaced apart and electrically connected together, thus, increasing the number of discharging edges on the electrode. In a first embodiment, the electrode comprises a plurality of concentric conductive rings electrically connected together. In a second embodiment, the electrode comprises a plurality of conductive planar elements electrically connected together in a generally puzzle-like configuration. In a third embodiment, the electrode comprises electrically conductive wires wrapped around the length of a cardiac catheter. In a fourth embodiment, electrically conductive wires are concentrically spiralled into a spiral patch configuration. In a fifth specific embodiment, a plurality of electrically isolated active sites are provided on the distal portion of an endocardial catheter.

Abstract: A defibrillation electrode for implantation on or about the heart and for connection to a defibrillation system. The electrode comprises a plurality of electrically conductive elements spaced apart and electrically connected together, thus, increasing the number of discharging edges on the electrode. In a first embodiment, the electrode comprises a plurality of concentric conductive rings electrically connected together. In a second embodiment, electrode comprises a plurality of conductive planar elements electrically connected together in a generally puzzle-like configuration. In a third embodiment, the electrode comprises electrically conductive wires wrapped around the length of a cardiac catheter. In a fourth embodiment, electrically conductive wires are concentrically spiralled into a spiral patch configuration. In a fifth specific embodiment, a plurality of electrically isolated active sites are provided on the distal portion of an endocardial catheter.

Abstract: An implantable cardiac defibrillation/cardioversion electrode. The electrode is elongated and comprises a distal active region and a proximal lead region. Conductive discharge and insulative materials occupy distinct surfaces along the length of the active region. The active region is preformed to adopt a planar spiral patch configuration under relaxed conditions. Additional flexible preformed insulative and conductive discharge wings are provided to attach to the corresponding surfaces of the active region. A method of implantation of the spiral patch is disclosed for deployment by straightening the electrode and introducing the same through an opening that approximates the cross section of the straightened electrode.

Abstract: A method of treating hemodynamic disfunction by simultaneously pacing both ventricles of a heart. At least one ECG amplifier is arranged to separately detect contraction of each ventricle and a stimulator is then activated for issuing stimulating pulses to both ventricles in a manner to assure simultaneous contraction of both ventricles, thereby to assure hemodynamic efficiency. A first ventricle is stimulated simultaneously with contraction of a second ventricle when the first fails to properly contract. Further, both ventricles are stimulated after lapse of a predetermined A-V escape interval. One of a pair of electrodes, connected in series, is placed through the superior vena cava into the right ventricle and a second is placed in the coronary sinus about the left ventricle. Each electrode performs both pacing and sensing functions. The pacer is particularly suitable for treating bundle branch blocks or slow conduction in a portion of the ventricles.

Abstract: The implantable cardioverter/pacer includes a pacer channel and a rate detect channel both receiving a cardiac signal representative of the ECG of patient. The pacing channel issues a pacing signal when the amplitude of the cardiac signal fails to exceed a first predetermined threshold within a predetermined time period. The rate detect channel has a variable gain amplifier which is controlled by an automatic gain control (AGC). The AGC increases the gain in the amplifier based upon the level of the cardiac signal applied thereto and upon the time since the last peak of the cardiac signal. A one shot receives the output of the variable gain amplifier and produces a heart rate signal. Both the pacing and the heart rate signals are applied to a microprocessor.

Abstract: Disclosed are an electrode configuration and a method for its use with an automatic implantable cardioverter/defibrillator. The electrode configuration includes a catheter electrode intravenously positioned within the heart of a patient wherein one electrode, defined by the catheter, is within the right ventricle and a second electrode, also defined by the catheter and spaced from the first electrode, is within the superior vena cava region. A third electrode, in the form of a flexible, substantially planar patch, is subcutaneously positioned outside the thoracic cavity in the region of the left ventricle. At the time of electrical discharge, or permanently, the first and second electrodes of the catheter are connected together. The electrode arrangement can be implanted without opening of the thoracic cavity by intravenously placing the catheter electrode within the heart of a patient and subcutaneously implanting the patch electrode between the skin and the thoracic cavity.

Abstract: A heart rate acceleration/deceleration detecting system particularly for use with an automatic defibrillator/cardioverter. The detection system detects a series of heart beats and determines, for a group of beats, such as on a beat-by-beat basis, whether the heart rate has accelerated above a first predetermined value. If such acceleration is determined, the system checks to see if the acceleration of the heart beats was followed by an immediate deceleration that exceeds a predetermined value. If a large acceleration followed by an absence of a large deceleration is detected, a signal is provided to an arrhythmia detecting logic circuit as an indication of an arrhythmia that may be appropriate for treatment by the defibrillator/cardioverter. The acceleration detection system is also capable of determining if a large deceleration preceded the detection of the large acceleration.

Abstract: An implantable cardioverting system wherein a cardioverting or defibrillating voltage is automatically applied across implantable electrodes associated with the heart of a patient. The cardioverting voltage is an exponentially-decaying voltage pulse that is chopped, or broken, at high frequencies to provide a voltage wave packet formed of a plurality of high-frequency cardioverting pulses. The voltage is provided by an internal storage capacitor coupled across implantable electrode leads that is charged to a predetermined voltage level. Upon discharge, an electronic switch is clocked at frequencies preferably in excess of 1 KHz to open and close the circuit formed of the storage capacitor and electrodes.

Abstract: An implantable cardiac electrode for use in defibrillation and methods of implanting same. The electrode has a metallic mesh electrode surface surrounded by an insulating material. At the proximal end of the electrode there is defined a fin area designed to facilitate placing and securing the electrode proximate the heart. The electrode may be implanted without major surgery in a number of ways, one of which requires a specialized insertion tool which cooperates with a pocket formed in the electrode.

Abstract: The fail safe architecture for a computer system includes a read only memory (ROM) self-check module, a random access memory (RAM) self-check module and operation code instructions (op code) self-check module which are actuated periodically by a non-maskable interrupt (NMI) to a microprocessor. The microprocessor then suspends the current applications routine being executed. If the self-check module detects a failure, the microprocessor enters a fail safe trap routine which initially resynchronizes the operation of the microprocessor and then delays the generation of a critical timing pulse (fail safe trigger) with a series of "jump to yourself" steps. The fail safe trigger signal activates a device which sends a fail safe square wave to a narrow bandwidth, digital, band-pass filter.

Abstract: A clocking system for providing periodic clocking or timing signals for use in an electronic circuit. The system includes a primary clock source, such as a crystal oscillator, that provides periodic clocking or timing signals at a predetermined frequency, and a back-up clock source that is similarly capable of providing periodic clocking or timing signals at the same predetermined frequency. The clocking signals of the primary source are monitored by a fault detecting circuit, such as a frequency monitoring circuit, which checks if the clock signals are occurring precisely at the predetermined frequency. If the frequency monitoring cirucit detects a frequency variation, or deviation, in the primary clocking source, a back-up clocking source is enabled which provides the clocking signals to the clock output terminal.

Abstract: A novel electrode apparatus and method for use with an automatic implantable cardioverter/defibrillator. The electrode apparatus includes a catheter electrode intravenously positioned within the heart of a patient wherein one electrode, defined by the catheter, is within the right ventricle and a second electrode, defined by the catheter, spaced from the first electrode, is within the superior vena cava. A third electrode, in the form of a flexible, substantially planar patch, is subcutaneously positioned outside the thoracic cavity proximate to the apex of the left ventricle. The third electrode is electrically connected with the second electrode of the catheter. The electrode arrangement can be implanted without opening of the thoracic cavity by intravenously placing the catheter electrode within the heart of a patient and subcutaneously implanting the patch electrode between the skin and the thoracic cavity.

Abstract: An implantable cardioversion system employing a bipolar electrode for R-wave sensing, the system utilizing heart rate averaging and probability density function techniques in determining whether or not the heart of a patient is to be automatically cardioverted. An improved bipolar electrode facilitates acquisition of a highly accurate R-wave. The implantable system is further provided with the capabilities of (1) providing, upon magnet-type interrogation, an audible indication of proper placement of the bipolar electrode in the body of a patient, (2) providing an audible indication to verify the status of the implanted device (activated or deactivated), (3) the capability of providing, upon request, a transmitted signal modulated with stored information corresponding to the number of times cardioversion of the patient has taken place, (4) the capability of preventing external cardioversion shock from being shunted across the electrodes, and (5) the capability of detecting average heart rate.

Abstract: A multiple electrode unitary intravascular cardiac catheter comprising a distal electrode for sensing and pacing, an intermediate electrode for sensing, pacing and cardioverting, and a proximal electrode for sensing and cardioverting. The catheter may also be employed in combination with an external patch electrode.

Abstract: A digital circuit requiring minimum power for accurately and reliably measuring the average pulse rate of a periodic signal. The circuit includes a plurality of flip-flop stages adapted to be configured by control gates either as a binary counter or a shift register in response to the pulses of the periodic input signal. Through a series of configuration gates, each pulse momentarily configures the circuit as a shift register and effects a shift operation, e.g. a divide-by-two operation. After each pulse, the circuit resumes a counter configuration and counts the clock pulses of a crystal controlled clock oscillator. After a few input pulses, the contents of the counter immediately after each shift operation indicates the average periodic rate of the periodic signal in much the same manner as a conventional R-C network. However, the digital circuit is not suseptable to drift caused by temperature changes and also moderates the effects of momentary irregularities in the periodic rate of the signal.

Abstract: An externally controlled implantable electronic device for delivering a cardioverting pulse of energy to an ailing heart. A defibrillator produces a first signal when its storage device is fully charged and ready to be discharged, and a second signal when a predetermined characteristic of an ECG signal is detected. An actuator is provided for determining the presence of both of these signals. If during a predetermined time period, there is a simultaneous occurrence of the first and second signals, then the defibrillator will be activated to deliver the cardioverting shock to the heart. In the absence of either of the two signals, the defibrillator will not deliver a shock.

Abstract: A data recording arrangement for recording ECG data within the body of a patient, for transmitting the ECG data to a point external to the body of a patient, and for recovering the transmitted ECG data is disclosed. The recording arrangement employs delta modulation circuitry for delta modulating the ECG data to obtain a delta modulated digital pulse train. The digital pulse train may be stored within the body of a patient for subsequent transmission external to the body of a patient. Transmission of the data external to the body of a patient may be by a piezoelectric transducer which transmits the digital data audibly for external detection and delta demodulation. Alternatively, delta demodulation may occur within the patient's body, and the demodulated analog signal may then be transmitted by FM, using the piezoelectric transducer to provide the FM audible signal detectable by an FM demodulator external to the body.

Abstract: The present invention relates to a method and apparatus for delivering two or more individual low-level pulses to correct certain cardiac arrhythmias such as high-rate ventricular tachycardia and ventricular fibrillation; at least the latter shocks are delivered in synchronism with a repeatable characteristic of the heart's electrical activity. Basically, the apparatus comprises an electrode sensor placed in the right ventricle of the heart or in the coronary sinus to act as a detector for the electrical activity of the heart. Connected to the electrode sensor is an arrhythmia detector chosen to detect such arrhythmias as ventricular tachycardia and ventricular fibrillation. Upon detection of one of these arrhythmias, the detector issues a signal which is interpreted by a programmable logic device to activate an energy storage device for delivering a first low-level shock to the heart through a shock delivering electrode. A slew rate detector is then activated by the logic device.