Direct-coupled output stage for rapid-signal biological stimulator
First Claim
1. A heart pacer comprising a battery supply, a pair of electrodes for applying a stimulating pulse to the heart of a patient, means connected to at least one of said electrodes for sensing heart activity, storage capacitor means, means responsive to said sensing means for determining the need for a stimulating pulse and in response thereto for connecting said storage capacitor means across said electrodes to apply a stimulating pulse to said patient'"'"'s heart, means for charging said storage capacitor means from said battery supply following the application of a stimulating pulse to said patient'"'"'s heart, and means operative following the application of a stimulating pulse to said patient'"'"'s heart for coupling said electrodes directly to each other and independent of said battery supply to allow charge stored in the interfaces between said electrodes and said patient'"'"'s tissue as a result of said stimulating pulse to be largely recovered, through said electrodes.
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Abstract
There is disclosed a direct-coupled output stage which is especially advantageous for use in an implantable heart pacer. In order to provide for charge balancing at the electrode/electrolyte interfaces, the electrodes are shorted to each other after a pacing pulse is generated. Not only is the use of a bulky coupling capacitor avoided, but the stored charge dissipates in a much shorter time, thereby minimizing the "blind" interval in the sensing cycle.
79 Citations
27 Claims
- 1. A heart pacer comprising a battery supply, a pair of electrodes for applying a stimulating pulse to the heart of a patient, means connected to at least one of said electrodes for sensing heart activity, storage capacitor means, means responsive to said sensing means for determining the need for a stimulating pulse and in response thereto for connecting said storage capacitor means across said electrodes to apply a stimulating pulse to said patient'"'"'s heart, means for charging said storage capacitor means from said battery supply following the application of a stimulating pulse to said patient'"'"'s heart, and means operative following the application of a stimulating pulse to said patient'"'"'s heart for coupling said electrodes directly to each other and independent of said battery supply to allow charge stored in the interfaces between said electrodes and said patient'"'"'s tissue as a result of said stimulating pulse to be largely recovered, through said electrodes.
- 5. A heart pacer comprising electrode means for supplying a stimulating current to the heart of a patient, means for sensing heart activity, control means responsive to said sensing means for determining the need for a stimulating current and in response thereto for causing a stimulating current to flow through said electrode means, and means operative following operation of said control means for enabling a passive discharge of the distributed capacitance in said patient'"'"'s heart.
- 13. A biological tissue stimulator for applying a rapidly varying signal to a site which is to have minimal net charge transfer comprising electrode means for applying a stimulating current to said site, control means for causing a rapidly varying direct-coupled stimulating current to flow through said electrode means, and means operative following operation of said control means for enabling a passive discharge of the distributed capacitance at said site.
- 21. An output circuit for a biological tissue stimulator to stimulate a site for which low net charge transfer is desired comprising a pair of electrodes for causing current flow through said site, charge storing means, means for connecting said charge storing means in series with said pair of electrodes when a stimulating current is to be delivered, and means for coupling said pair of electrodes to each other following operation of said connecting means.
Specification