Abstract: An implantable atrial defibrillator provides a pulse of defibrillating electrical energy to the atria of the heart in synchronism with sensed R waves in response to non-coincident sensing of an R wave at first and second areas of the heart. The defibrillating pulse is provided after a predetermined number of consecutive R waves are non-coincidently sensed to assure reliable synchronization. The atrial defibrillator is also operational in a marker mode wherein a number of synchronization marker pulses are delivered to the heart for detection on an externally generated electrocardiogram. The atrial fibrillation detector of the defibrillator is normally disabled and is activated when the sensed ventricular activity indicates a probability of atrial fibrillation to conserve a depletable power source. An endocardial lead is also described which ensures that the delivered atrial defibrillating electrical energy is substantially confined to the atria of the heart.

Abstract: An implantable atrial defibrillator provides a pulse of defibrillating electrical energy to the atria of the heart in synchronism with sensed R waves in response to non-coincident sensing of an R wave at first and second areas of the heart. The defibrillating pulse is provided after a predetermined number of consecutive R waves are non-coincidently sensed to assure reliable synchronization. The atrial defibrillator is also operational in a marker mode wherein a number of synchronization marker pulses are delivered to the heart for detection on an externally generated electrocardiogram. The atrial fibrillation detector of the defibrillator is normally disabled and is activated when the sensed ventricular activity indicates a probability of atrial fibrillation to conserve a depletable power source. An endocardial lead is also described which ensures that the delivered atrial defibrillating electrical energy is substantially confined to the atria of the heart.

Abstract: An implantable atrial defibrillator provides a pulse of defibrillating electrical energy to the atria of the heart in synchronism with sensed R waves in response to non-coincident sensing of an R wave at first and second areas of the heart. The defibrillating pulse is provided after a predetermined number of consecutive R waves are non-coincidently sensed to assure reliable synchronization. The atrial defibrillator is also operational in a marker mode wherein a number of synchronization marker pulses are delivered to the heart for detection on an externally generated electrocardiogram. The atrial fibrillation detector of the defibrillator is normally disabled and is activated when the sensed ventricular activity indicates a probability of atrial fibrillation to conserve a depletable power source. An endocardial lead is also described which ensures that the delivered atrial defibrillating electrical energy is substantially confined to the atria of the heart.

Abstract: An implantable atrial defibrillator provides cardioverting electrical energy to the atria of a human heart in need of cardioversion. The atrial defibrillator includes a first detector for detecting ventricular activations of the heart, a second detector for detecting atrial activity of the heart, and an atrial fibrillation detector responsive to the second detector for determining when the atria of the heart are in need of cardioversion. The atrial defibrillator further includes a cardioverter for applying the cardioverting electrical energy to the atria of the heart when the atria of the heart are in need of cardioversion, and a timer delay stage responsive to the first detector for causing the cardioverter to apply the cardioverting electrical energy to the atria of the heart a predetermined delay time after the first detector detects one of the ventricular activations and before the T wave of the heart immediately following the one of the ventricular activations.

Abstract: A defibrillator designed to determine and display (1) the current which is anticipated to be provided to a patient by a defibrillation pulse generated by the defibrillator when the former is to be provided in the form of an energy dose and (2) the energy which is anticipated to be provided to a patient by a defibrillation pulse generated by the defibrillator when the former is to be provided in the form of a current dose. The defibrillator is also designed to determine and display how changes in the transthoracic impedance of the patient will change (1) the magnitude of the selected energy level of the defibrillation pulse when the defibrillator is in the energy dose mode and (2) the magnitude of the selected current level of the defibrillation pulse when the defibrillator is in the current dose mode.

Abstract: An implantable atrial defibrillator provides cardioverting electrical energy to the atria of a human heart in need of cardioversion. The atrial defibrillator includes a first detector for detecting ventricular activations of the heart, a second detector for detecting atrial activity of the heart, and an atrial fibrillation detector responsive to the second detector for determining when the atria of the heart are in need of cardioversion. The atrial defibrillator also includes a cardioverting stage for applying the cardioverting electrical energy to the atria of the heart when the atria of the heart are in need of cardioversion and when the time between immediately successive ventricular activations is greater than a preselected minimum time interval.

Abstract: An implantable device prevents tachyarrhythmias of a human heart which has arrhythmogenic tissue such as a myocardial infarction site. The device includes a plurality of electrodes configured for electrical contact with the heart and for placement in proximity to the arrhythmogenic tissue and a sensor including a single sensing electrode for sensing electrical activations of one chamber of the heart. A pulse generator coupled to the plurality of electrodes and responsive to the sensor provides the plurality of electrodes with an electrical pulse during each sensed electrical activation.

Abstract: An implantable device assists in the diagnosis of myocardial ischemia of a human heart and includes a plurality of electrodes and a like plurality of sense amplifiers for generating an electrogram for each of the electrodes. A digital to analog converter reads the voltage magnitudes of the electrogram ST segments which are then stored in a memory. An implantable receiver/transmitter is arranged to transmit the magnitudes of the electrogram ST segments to a nonimplanted external receiver.

Abstract: A discriminating connector (38) can be connected to a defibrillation electrode (36), but not to an ECG monitoring electrode (10), even though both electrodes (38 and 10) have identical conducting posts (50 and 12). The discriminating connector (38) is formed by upper and lower members (40 and 42) and a pivot (44) that connects the upper and lower members (40 and 42) so as to define an opening (43). A mating receptacle (48) is disposed within an upper wall (74) of the opening (43). A distance (49) between the mating receptacle (48) and the pivot (44) is equal to or greater than a distance (59) between the conducting post (50) and an outer edge (53) of the defibrillation electrode (36) so as to permit the conducting post (50) to be received by the mating receptacle (48). A conductive receptacle (15) in a prior art ECG connector (11) is identical to the mating receptacle (48) and can be attached to the conducting post (50) on the defibrillation electrode (36).

Abstract: An automated ventilation, CPR and circulatory assistance apparatus includes an airway apparatus 10, a vest 12 including an inflatable bladder 18, and an abdominal restraint 14 including an inflatable bladder 22. An airway pneumatic control apparatus 84, a vest pneumatic control apparatus 86, and an abdominal restraint pneumatic control apparatus 88 are in fluid communication with the airway apparatus, the vest bladder, and the abdominal restraint bladder, respectively, and responsive to respective first and second states in an airway control signal AWC, a vest control signal VC, and an abdominal restraint control signal ARC to alternately inflate and deflate the patient's lungs, the vest bladder, and the abdominal restraint bladder, respectively. Provision is made for selectively adjusting the volume of gas that is coupled to the patient's lungs, and the maximum pressures that are obtained in the vest bladder and the abdominal restraint bladder. An electronic control means (FIGS.

Abstract: A bipolar electrode 10 capable of sensing the electrical activity in a localized portion of body tissue includes a disc 12 having a surface 12A adapted to be brought into proximity to a surface of the body tissue, and an inner electrode or conductive spike 14 and a first outer electrode or helix 16 that are supported by disc 12 and that extend from surface 12A. Corkscrew 16 surrounds spike 14, and the tip 16A of helix 16 is located at a greater distance away from surface 12A than is tip 14A of spike 14. Tripolar electrodes 30, 50 utilize this structure along with a second outer electrode or helix 38 (in tripolar electrode 30) and an annular conductive ring 58 (in tripolar electrode 50) for respectively applying pacing and defibrillation pulses to the heart.

Abstract: A bellows 10 is adapted to be placed on the chest of a patient and includes a closed chamber which is coupled by a conduit 20 and a first valve apparatus 22 to an airway apparatus 24 adapted to be inserted into the patient's airway, and by a second valve apparatus 26 and a conduit 28 to an inflatable bladder 30 forming part of an abdominal restraint 32 adapted to be secured about that portion of the patient's body in the region of the abdomen. As the bellows is being compressed by the application of manual force, valve apparatus 22 functions to couple the gas being expelled from the bellows into the patient's lungs via airway apparatus 24 (with valve apparatus 22 also functioning to limit the resultant lung pressure to a desired value), whereby the patient's intrathoracic pressure is increased due to the combination of the manual force applied to the patient's chest through the bellows and the pressure generated in the patient's lungs.

Abstract: A body implantable device for providing electrical stimulation to living animal tissue. The device includes a pulse generator having at least one alterable output parameter and circuitry responsive to first externally generated signals for altering the alterable output parameter in predetermined correspondence with the number of said first signals. The output parameter altering circuitry is enabled only during the occurrence of second signals having characteristics discriminable from the characteristics of the first signals. In a preferred embodiment, the first signals are pulses of radio frequency energy and the second signals are magnetic. The invention may be embodied in a cardiac pacemaker of either the asynchronous or demand type and the second signals may be employed to cause a demand cardiac pacemaker to revert to an asynchronous operation.

Abstract: A demand cardiac pacemaker is disclosed as comprising an input sensing circuit portion of improved sensitivity to heart beat signals of relatively low amplitude. In particular, the input circuit portion includes a first sensing, bipolar transistor biased by a GaAsP light-emitting diode (LED), and a second amplifying, bipolar transistor whose base is coupled to the collector of the first transistor. Further, the output of the second transistor as taken from its collector is fed back through a suitable shaping circuit to the emitter of the first transistor, whereby controlled high gain and desired frequency/amplitude discrimination characteristics are achieved from the first and second transistors, so that the input sensing portion of the pacemaker circuit is responsive to heart signals above a predetermined level without sacrificing gain.