Cardiac pacemaker with selective unipolar/bipolar pacing
First Claim
1. A dual chamber cardiac pacemaker for pacing the atrial and ventricular chambers of the heart in any combination of unipolar and bipolar pacing modes, comprising:
- atrial and ventricular leads each including a stimulating cathodic electrode and an anodic electrode to be positioned within the respective chamber of the heart.a dc power source for delivering a voltage of predetermined polarity and magnitude between a power terminal and a ground reference terminal thereof,circuit means coupled across the power and reference terminals of said power source for sequentially applying said voltage as an electrical stimulus to first one and then the other of said stimulating electrodes,a case housing said circuit means, said case including a third anodic electrode,said circuit means includingswitch means for selectively conductively connecting at least one among the three anodic electrodes to the reference terminal of the power source at all times, andcontrol means for completing a conductive path between the power terminal of the power source and the stimulating electrode for the respective chamber undergoing pacing while simultaneously actuating said switch means to maintain a conductive connection between the reference terminal of the power source and one of said anodic electrodes selected according to the desired pacing mode for said respective heart chamber undergoing pacing, said control means includingmeans for selectively applying control voltages of the same polarity as the voltage at said power terminal to said switch means for actuation thereof to provide the respective conductive connections, andmeans for maintaining each of said control voltages at a magnitude greater than the magnitude of the voltage at said power terminal to maintain said switch means in the desired actuated state and to avoid undesired switching of said reference terminal among said anodic electrodes.
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Accused Products
Abstract
A dual chamber cardiac pacemaker is programmable for either unipolar or bipolar pacing of the atrium or the ventricle, independently of the pacing mode for the other chamber. Transistor switches are utilized for selectively connecting the various anodic electrodes to ground such that one of those electrodes is grounded at all times and isolation is maintained from circuit paths for non-selected modes. Switch control is effected using signals having the highest voltage level of proper polarity in the system, to assure maintenance of the selected switch states despite possible random voltages arising from external influences. Cumulative buildup of charge on coupling capacitors is prevented by selectively and actively discharging them after the respective chamber is paced.
44 Citations
5 Claims
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1. A dual chamber cardiac pacemaker for pacing the atrial and ventricular chambers of the heart in any combination of unipolar and bipolar pacing modes, comprising:
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atrial and ventricular leads each including a stimulating cathodic electrode and an anodic electrode to be positioned within the respective chamber of the heart. a dc power source for delivering a voltage of predetermined polarity and magnitude between a power terminal and a ground reference terminal thereof, circuit means coupled across the power and reference terminals of said power source for sequentially applying said voltage as an electrical stimulus to first one and then the other of said stimulating electrodes, a case housing said circuit means, said case including a third anodic electrode, said circuit means including switch means for selectively conductively connecting at least one among the three anodic electrodes to the reference terminal of the power source at all times, and control means for completing a conductive path between the power terminal of the power source and the stimulating electrode for the respective chamber undergoing pacing while simultaneously actuating said switch means to maintain a conductive connection between the reference terminal of the power source and one of said anodic electrodes selected according to the desired pacing mode for said respective heart chamber undergoing pacing, said control means including means for selectively applying control voltages of the same polarity as the voltage at said power terminal to said switch means for actuation thereof to provide the respective conductive connections, and means for maintaining each of said control voltages at a magnitude greater than the magnitude of the voltage at said power terminal to maintain said switch means in the desired actuated state and to avoid undesired switching of said reference terminal among said anodic electrodes. - View Dependent Claims (2)
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3. In a dual chamber cardiac pacemaker adapted for selective stimulation of the atrial and ventricular chambers of the heart of a pacemaker patient in any combination of unipolar and bipolar pacing modes;
- said pacemaker including a case, a pulse generator housed in the case, a connector with terminals affixed to the case for electrically coupling a pair of lead assemblies, each including a stimulating cathodic electrode and an anodic electrode for introduction into a respective chamber of the patient'"'"'s heart, to the pulse generator for delivery of voltage pulses of predetermined polarity and magnitude from the generator to the respective electrodes relative to a ground reference terminal of the generator, said case having an anodic electrode for electrical contact with the body tissue and fluid of the pacemaker patient when the pacemaker is implanted;
an improved output isolation circuit comprising;three semiconductor switch means each having relatively low on resistance and relatively high off resistance, and each connected at one side to the ground reference terminal of the pulse generator and respectively connected at the other side to the connector terminals for the anodic electrodes of said pair of lead assemblies and to said anodic electrode of the case, for electrical connection of each of said anodic electrodes to said ground reference terminal through a respective one of said switch means when in the on state, first and second means for selectively delivering the voltage pulses of said pulse generator to the connector terminals for the stimulating cathodic electrodes of said pair of lead assemblies, for sequential stimulation of the atrial and ventricular chambers, and means for selectively actuating each of said switch means to the on and off states to electrically connect at least one of said anodic electrodes to the ground reference terminal at all times, and, during selective delivery of any given one of said voltage pulses to the connector terminals, to electrically connect to the ground reference terminal one of said anodic electrodes applicable to the pacing mode selected for the heart chamber then undergoing stimulation, said means for selectively actuating each of said switch means including means for applying control voltages of predetermined magnitude and the same polarity as said voltage pulses to each of said switch means, and means for maintaining each of the control voltages at a magnitude exceeding the magnitude of said voltage pulses. - View Dependent Claims (4)
- said pacemaker including a case, a pulse generator housed in the case, a connector with terminals affixed to the case for electrically coupling a pair of lead assemblies, each including a stimulating cathodic electrode and an anodic electrode for introduction into a respective chamber of the patient'"'"'s heart, to the pulse generator for delivery of voltage pulses of predetermined polarity and magnitude from the generator to the respective electrodes relative to a ground reference terminal of the generator, said case having an anodic electrode for electrical contact with the body tissue and fluid of the pacemaker patient when the pacemaker is implanted;
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5. A stimulus generator for an implantable cardiac pacemaker adapted to pace both chambers of one side of the heart via atrial and ventricular leads each having a cathode and an anode, and to do so with unipolar or bipolar stimulation of either chamber independently of the mode of stimulation of the other chamber, said stimulus generator comprising:
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a first pair of terminals for respectively connecting said generator to the anode and cathode of the atrial lead and a second pair of terminals for respectively connecting said generator to the anode and cathode of the ventricular lead, means for sequential delivery of electrical stimuli from said generator to said first and second pairs of terminals, means establishing a point of ground potential for said generator, means for housing said generator, said housing means having integral therewith an anode for making contact with the body saline of a patient, three semiconductor switches each actuable separately to an "on" state and an "off" state, and each having a pair of electrodes establishing a low resistance conduction path therethrough when the respective switch is actuated to the "on" state, one of said electrodes of all three of said switches being connected to said point of ground potential and the other of said electrodes of each of said switches being respectively connected to said anode connection terminal for the atrial lead, said anode connection terminal for the ventricular lead, and said anode integral with the housing means, and means for selectively and independently actuating each of said three semiconductor switches for maintaining at least one of said switches in the "on" state at any given time during operation of the stimulus generator, including means for applying control voltages of predetermined magnitude and the same polarity as said electrical stimuli to each of said switches, and means for maintaining each of the control voltages at a magnitude exceeding the magnitude of said electrical stimuli.
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Specification