Defibrillation pacing circuitry
First Claim
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1. An implantable cardiac stimulus system comprising:
- implantable electrodes for the delivery of electrical stimulus to a patient;
operational circuitry including at least an H-bridge circuit comprising a high side and a low side, wherein the H-bridge circuit comprises first and second legs connected between the high side and the low side thereof, wherein the first leg of the H-bridge circuit comprises first and second current switching elements and the second leg of the H-bridge circuit comprises third and fourth current switching elements, the H-bridge comprising output nodes for coupling to patient tissue via the implantable electrodes, wherein a first output node is located on the first leg between the first and second current switching elements and a second output node is located on the second leg between the third and fourth current switching elements, the operational circuitry further comprising a constant current circuit connected to the low side of the H-bridge circuit anda canister for housing at least the battery and operational circuitry;
wherein the first and fourth current switching elements define a first pair of current switching elements;
wherein the operational circuitry is configured to select the first pair of current switching elements to generate a stimulus of a first polarity for application via the first and second output nodes; and
wherein the constant current circuit comprises a bypass switch and a pacing resistor in parallel with one another and coupled to the low side of the H-bridge;
wherein the operational circuitry is configured to close the bypass switch to deliver a defibrillation output, and to open the bypass switch to force current from the low side of the H-bridge through the pacing resistor to deliver a pacing output andwherein the constant current circuit is configured to control operation of the fourth current switching element by monitoring a voltage across the pacing resistor during a stimulus of the first polarity to force the stimulus to be a substantially constant current pacing stimulus.
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Abstract
Electrical circuit componentry is switchable into a defibrillator circuit to deliver a constant pacing current to a patient. The circuitry may include a constant current source inserted in a leg of the defibrillator circuit or a resistor of selected value inserted between a high voltage source and the high side of a defibrillator circuit.
77 Citations
4 Claims
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1. An implantable cardiac stimulus system comprising:
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implantable electrodes for the delivery of electrical stimulus to a patient; operational circuitry including at least an H-bridge circuit comprising a high side and a low side, wherein the H-bridge circuit comprises first and second legs connected between the high side and the low side thereof, wherein the first leg of the H-bridge circuit comprises first and second current switching elements and the second leg of the H-bridge circuit comprises third and fourth current switching elements, the H-bridge comprising output nodes for coupling to patient tissue via the implantable electrodes, wherein a first output node is located on the first leg between the first and second current switching elements and a second output node is located on the second leg between the third and fourth current switching elements, the operational circuitry further comprising a constant current circuit connected to the low side of the H-bridge circuit and a canister for housing at least the battery and operational circuitry; wherein the first and fourth current switching elements define a first pair of current switching elements; wherein the operational circuitry is configured to select the first pair of current switching elements to generate a stimulus of a first polarity for application via the first and second output nodes; and wherein the constant current circuit comprises a bypass switch and a pacing resistor in parallel with one another and coupled to the low side of the H-bridge; wherein the operational circuitry is configured to close the bypass switch to deliver a defibrillation output, and to open the bypass switch to force current from the low side of the H-bridge through the pacing resistor to deliver a pacing output and wherein the constant current circuit is configured to control operation of the fourth current switching element by monitoring a voltage across the pacing resistor during a stimulus of the first polarity to force the stimulus to be a substantially constant current pacing stimulus. - View Dependent Claims (2, 3, 4)
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Specification