Abstract: An apparatus and method for delivering electrical shock therapy in order to treat atrial tachyarrhythmias such as atrial fibrillation is presented. The ventricular rhythm of certain patients during an episode of atrial fibrillation may be such that shockable R—R intervals are infrequent or do not occur at all. Continuous electrical stimulation of the atria after detection of an atrial tachyarrhythmia may be utilized to modify the ventricular rhythm in such patients to increase the frequency of shockable R—R intervals.

Abstract: An atrial defibrillation system monitors activity of a heart, detects atrial fibrillation, and cardioverts detected atrial fibrillation. The system includes an implantable atrial defibrillator including a plurality of operating stages for monitoring heart activity, detecting atrial fibrillation, and cardioverting atrial fibrillation, a message generator for generating messages indicative of operating stage operation status, and a transmitter to transmit the messages indicative of operating stage operating status. A nonimplantable communication device is dimensioned to be hand-held and includes a receiver for receiving the transmitted messages indicative of operating stage operation status, an addressable memory for storing a plurality of voice signals, a decoder responsive to received messages indicative of operating stage operation status for addressing selected ones of the stored voice signals, and a converter for converting the selected voice signals to audible sound.

Abstract: A method is provided for removing an implanted cardiac lead having a lead body and at least one conductive electrode from a mammalian body. The method includes the steps of providing an indifferent electrode, establishing electrical contact between the indifferent electrode and the body, and providing a generator of electrical energy. The method further includes the steps of coupling the generator between the conductive electrode and the indifferent electrodes and causing the generator to apply electrical energy between the conductive electrode and the indifferent electrode. The energy has a magnitude sufficient to produce gas by electrolysis between the conductive electrode and fibrotic tissue grown around the electrode. Thereafter, the lead body is pulled in an anterior direction relative to the mammalian body to remove the cardiac lead from the mammalian body.

Abstract: A capacitive measuring pad is constructed of transverse conductive strips separated by a compressible insulator to form a matrix of pressure sensitive capacitive nodes. The nodes are repetitively scanned in sequence by a microcomputer to measure their respective capacitances, from which measurements a pressure map is then derived. The resulting pressure map may be displayed on a color graphics monitor with different colors representing diffrent pressures. Node capacitance is found by measuring the response of the mode to a driving signal of a known voltage. This measurement is accomplished by connecting one of the node's transverse conductive strips to the driving source and the node's other conductive strips to a sense amplifier. In order to isolate the node of interest from the influence of surrounding nodes, all of the conductive strips except the two intersecting the selected node are connected to ground.

Abstract: A pressure distribution measuring system includes a pad of insulating material disposed between two linear arrays of electrodes to form a matrix of capacitive nodes. A capacitance related output signal that is obtained from a node of interest is used as a feedback signal and applied to other capacitors that are connected in common with the node of interest. The feedback signal inhibits the flow of current through these commonly connected capacitors, and thereby isolates the measured signal from any changes in the capacitance of these other capacitors. The pad includes a cental array of linear electrodes sandwiched between two layers of dielectric foam material. Two outer, aligned linear electrode arrays, oriented perpendicular to the central array, are respectively disposed on the outside surfaces of the dielectric layers. In a preferred form, alternating electrodes in each outer array are located on opposite sides of a support substrate.

Abstract: A method of controlling cardiac ventricular fibrillation and other tachyarrhythmias. A catheter carrying a first and second electrode is located in the right ventricle such that the first electrode is located in the right ventricle and the second electrode is located in the superior vena cava. A third electrode is located either at the chest wall or at the abdominal cavity. The third electrode can be implanted subcutaneously in the left chest wall. It can also be located in the abdomen immediately beneath the diaphragm. It could also be implanted in the epigastric area overlying the superficial abdominal muscles and underneath the skin and fat. The second and third electrodes are sequentially paired and pulsed with the first electrode to control ventricular fibrillation and other tachyarrhythmias.

Abstract: A method of controlling cardiac ventricular fibrillation and other tachyarrhythmias by delivery of two time-separated current pulses to separate pairs of electrodes spatially placed in, around, or on the heart. The technique produces a temporal and spatial summation of the delivered current, which results in a dramatic reduction in the voltage, current, and energy required for defibrillation, or cardioversion, and allows the use of a smaller implantable pulse generator. The new system achieves a more uniform distribution of current within the ventricular myocardium, thereby reducing the risk of tissue damage and increasing the margin of safety between effective shocks and myocardial depressing or damaging shocks.

Abstract: Apparatus and method for measurement and control of blood pressure are disclosed. Blood pressure is indirectly continually monitored without use of a pressure transducer by sensing the pulse transit time to different sites in an artery, which transit time is inversely related to blood pressure, and developing pulses therefrom which are utilized to form arterial pulse waves, the comparison between which provide an indication of measured blood pressure. This indication is used to control blood pressure by controlling automatic release of a suitable drug into the body in amounts and over a time period as needed. The unit for measuring blood pressure includes two sets of electrodes positioned adjacent to but outside an artery at two sites (with the electrodes implanted or outside the body).