Abstract: In using electrogram signals to determine physiologic conditions like ischemia, the bad cardiac cycle information due to noise, axis shifts in the cardiac electrical axis, and the like must be removed if the electrogram signal can be made to be a good indicator. If this is accomplished through the adaptive filtering techniques shown here, the signal can be used to drive a closed loop therapy system responsive to those physiologic conditions discernible from good cardiac cycle electrocardiogram signals.

Abstract: Miniature defibrillators and cardioverters detect abnormal heart rhythms and automatically apply electrical therapy to restore normal heart function. Therapy decisions are typically based on the time between successive beats of various chambers of the heart, such as the left atrium and left ventricle. To prevent confusing a left ventricle beat for a left atrium beat, some devices use cross-chamber blanking, a technique which disables sensing of atrial beats for a certain time period after sensing. Conventionally, these devices lack any mechanism for adjusting length of this period. Accordingly, the inventor devised a implantable device including a mechanism for adjusting this time period. This mechanism ultimately allows tailoring of the cross-chamber blanking period to fit the needs of individual patients.

Abstract: A method for reducing the affects of intrinsic detection latency in a cardiac rhythm management device, wherein said method is initiated immediately prior to delivering a stimulation pulse to the heart tissue. A coincidence of intrinsic and cardiac rhythm management initiated stimulus or the delivery of a stimulation pulse proximate the time of an intrinsic event due to intrinsic detection latency may results in delivery of unnecessary backup stimulus and/or imprecise determination of a pacing threshold. When stimulating the heart, the timing sequence for delivering a stimulation pulse typically depends upon the timing of a previous intrinsic or device initiated event. Further, the method of the present invention reduces the affects of intrinsic detection latency thereby facilitating improved detection of capture and determination of capture threshold for minimizing power consumption while assuring therapeutic efficacy.

Abstract: A free-standing device for the testing of ECT (electroconvulsive therapy) instruments, and for training doctors in using such instruments, includes circuits to generate electrical wave forms which simulate the EEG (electroencephalograph) detectable brain waves, EMG (electromyograph) muscle activity and heart beats of a patient undergoing ECT. In one embodiment the ECT output leads of the ECT instrument are plugged into the device, the training doctor selects the ECT current and the device generates response EEG and EMG waveforms. It also measures the current and displays its measurement as a test of the accuracy of the stimulus selection controls of the ECT instrument.

Abstract: An apparatus for non-invasive flow indication through a rotary blood pump. The apparatus includes a blood pump adapted for implantation into a patient. The blood pump has a moving mechanism which contacts blood and imparts energy to the blood to move the blood in the patient at a desired flow rate. The apparatus includes a mechanism for causing the moving mechanism to move the blood. The causing mechanism is engaged with the moving mechanism. The causing mechanism receiving energy to power the causing mechanism. The apparatus comprises a sensorless flow indicator connected to the blood pump to identify the flow of blood through the pump based only on an energy balance between the energy imparted to the blood by the moving mechanism and the energy received by the causing mechanism. A method for determining blood flow in a patient. The method includes the steps of providing energy to a blood pump implanted in a patient to operate the pump.

Abstract: An implantable monitor for collecting and storing for later telemetric readout physiologic data relating to cardiopulmonary performance. The monitor device includes an accelerometer and associated signal processing circuitry for analyzing the accelerometer output signal and deriving therefrom activity, respiratory, pulse pressure and heart sound information helpful in assessing the efficacy of therapy being rendered to the patient.

Abstract: An implantable electrical device comprising an RV coil and a pacing probe. The RV coil provides defibrillation and cardioversion waveforms to the heart and the pacing probe provides pacing signals to the heart and also acts as a sensor of the heart's intrinsic activity. The pacing probe is advantageously positioned within the apex of the heart. The device includes a controllable interconnect circuit that interconnects the RV coil and the pacing probe so that when the RV coil provides a defibrillation or cardioversion therapeutic shock to the heart, a portion of the energy provided to the RV coil is provided to the pacing probe so that an electrical shock is simultaneously provided to the apex for defibrillation or cardioversion purposes. In the preferred embodiment, a shunt resistor is positioned in series with the pacing probe so that the current being supplied to the pacing probe is limited.

Abstract: A system for precisely locating the distal end of a catheter or an electrical stimulation and/or sensing lead, particularly a pacing lead or a defibrillation lead, within a patient's body. In a first embodiment employing a passive LC resonant circuit having a resonant oscillating frequency incorporated into a catheter or lead distal tip which may be located by means for and the steps of generating a field outside the patient's body at the resonant oscillating frequency encompassing the patient's body and the implanted catheter for a predetermined time to cause the resonant circuit to store energy and oscillate, terminating the generated field, whereby the resonant circuit continues to oscillate as the stored energy is dissipated and creates a re-radiated magnetic field, detecting the re-radiated magnetic field, and determining the location of the catheter distal tip as a function of the detected re-radiated magnetic field.

Abstract: A process and device to control a cardiac pacemaker enslaved to at least one physiological parameter. The pacemaker also possesses a mode of desynchronization of the ventricular stimulation when the atrial rhythm is too rapid for synchronous operation. One compares a detected coupling interval (PP) with an escape interval calculated by the enslavement (EI.sub.ASSERV). The calculated enslavement escape interval is preferably decreased by a prematurity factor (x), for example, 0 to 50%, preferably approximately 37.5%, of the calculated escape interval. After the comparison, one counts the number of cardiac cycles for which the coupling interval detected is less than the calculated escape interval, and one triggers the mode of desynchronization (FALLBACK) when the count exceeds a given threshold (y), for example 50 to 75%, preferably approximately 75% of the total number (N) of cardiac cycles analyzed.

Abstract: An implantable cardiac pacemaker having programmable stimulating pulse amplitudes selectable by means of an external programming unit. The pacemaker includes charge pump circuitry for developing a stimulating pulse voltage on an output capacitor. The output capacitor is charged to a selected level identified by a multiple-bit amplitude value communicated to the implanted device from the external programmer. The pacemaker is also provided with circuitry for monitoring the depletion level of its battery and for generating an indicator signal when the battery has depleted beyond a predetermined level. Associated with the charge pump circuitry is a selectively activated comparator circuit for controlling the charging of the output capacitor. Prior to generation of the indicator signal, the charge pump circuitry remains deactivated for some programmed output amplitudes, the level of output capacitor charging being proportional to the battery voltage.

Abstract: A system for treating the malfunctioning heart of a patient includes means which derive at least one electrical signal from the patient's heart and means which derive at least two physiologic signals from or related to the patient's circulatory system. The physiologic signals, or functions thereof, are weighted and algebraically summed in a central processing unit, which may be a programmable microprocessor, having a RAM and a ROM, receives and responds to the at least one electrical signal and to the at least two physiologic signals. Output means, which may include a heart assist pump, pacers, drug delivery devices and cardioverting/-defibrillating apparatuses, controlled by the central processing unit provides corrective measure(s) to the patient. Heart-rate zone signals and the algebraic sum, at any given time effect selection of a particular treatment modality, if needed.

Abstract: In the stimulation of living tissue the reaction thereof is usually superimposed with polarization phenomena to such a degree that the reaction cannot be recognized in the electrical signal. To avoid this problem, a curve of the measured tissue potential is intermediately stored in a first memory after each stimulation, and the intermediately stored curve is then always used for updating the current signal curve. The current signal curve is stored in a second memory whenever an absence of a tissue reaction to the stimulation occurs.

Abstract: An apparatus to innervate a deinnervated lung diaphragm and pace the deinnervated diaphragm with a normal innervated lung diaphragm. The apparatus has a sensing device sense operation of normal innervated lung diaphragm. The device produces a signal representative of the operation of the normal innervated diaphragm. The signal is modified in accordance with a set pattern to provide a modified signal showing the rate and duration of inspiration for the normal, innervated diaphragm. A pulse generator is fed by the modified signal to produce a pulse. A stimulator innervates the deinnervated diaphragm at the same rate and duration as a normal innervated lung diaphragm. A method of operating the apparatus is also described.

Abstract: A method is disclosed for combined cardiac pacing and defibrillating with an implanted pacer/defibrillator having sensing and pacing leads connected to the atrium and the ventricle. P-waves and R-waves are sensed, and V--V timer and a V--A timer are reset if an R-wave is sensed. If an R-wave is sensed during the V--V timer interval, a pacing stimulus to the ventricle is inhibited. If a P-wave is sensed during the V--A timer interval, a pacing stimulus to the atrium is inhibited. In an R-wave is sensed during the V--V timer interval, arrhythmia therapy is provided if an arrhythmia is determined to be present. If the sensed ventricular rate is greater than a selected tachycardia rate but is less than a selected fibrillation rate, then a determination is made whether the sensed atrial rate is greater than a selected fibrillation rate, and if so, the V--V and V--A timers are reset, but if the sensed atrial rate is not greater than a selected fibrillation rate, then arrhythmia therapy is provided.