BODY ORGAN STIMULATOR

• US 3,835,865 A
• Filed: 07/07/1972
• Issued: 09/17/1974
• Est. Priority Date: 07/10/1970
• Status: Expired due to Term

• Current Assignee: Ventritex Incorporated (Abbott Laboratories)
• Original Assignee: David Lee Bowers
• Inventors: Bowers, David Lee
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/269,611
• Time in Patent Office: 802 Days
• Field of Search: 128/2.1R,419CD,419E,419P,419R,419S,421,422,423 307/268 328/66,68,74
• US Class Current: 607/13
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371

Abstract

The output circuit of an electric stimulator is connected to an organ such as the heart through a coupling capacitor. A semiconductor switch is triggered with a short pulse so that it partly discharges the capacitor and stimulates the organ. Immediately following the turn off of the first switch, a second switch is activated to recharge the capacitor to its initial state during which time reverse current is delivered momentarily to the heart. In one embodiment, after the first switch turns off to terminate the discharge of the capacitor which stimulates the heart, the current through the heart is reversed immediately by recharging the capacitor through a diode which is connected to a supply line and is in series with the capacitor and the heart. Turn-off of the first switch starts the diode conducting heavily. A high input impedance detector determines whether there is a natural electric signal on the organ and turns on a generator which provides the trigger pulse if there is no natural signal. The circuit is arranged so that the detector and output circuit present a high impedance to the organ.

Claims

1. An electric organ stimulator comprising:

a. terminals which are adapted to be connected to a d-c source, b. a capacitor, c. a first output terminal connected to one side of said capacitor and adapted to be connected to an organ load, d. a second output terminal connected to a source terminal and adapted to be connected to an organ load, e. first and second substantially unidirectionally conductive means each having main conductive paths connected in series with each other between said d-c source terminals, at least the first conductive means including a control element for selectIvely controlling conduction thereof in response to a signal on said element, the other side of said capacitor being connected to a point between said conductive means, f. means for applying a control signal to said control element to cause said first conductive means to conduct for a predetermined interval at a time when stimulation of an organ is desired, conduction by said first conductive means causing current flow through said capacitor and between said organ load output terminals to thereby alter the initial state of charge on the capacitor rapidly, said second unidirectionally conductive means remaining substantially nonconductive when said first means is conducting, g. said second conductive means responding to termination of conduction of said first conductive means by conducting and causing current flow through said capacitor and between said organ terminals to thereby substantially reestablish the initial state of charge on said capacitor rapidly, h. a high value resistor means connected between one source terminal and to said capacitor, said resistor means continuing to conduct after said second conductive means stops conducting whereby to complete reestablishing the charge on said capacitor to its initial state.

2. The stimulator in accordance with claim 1 wherein:

a. said first unidirectionally conductive means is a semi-conductor means having load terminals serially connected in said conductive path and a control terminal to which said control signal is applied to cause said first conductive means to conduct, and b. said second unidirectionally conductive means is a diode.

3. The stimulator in accordance with claim 1 wherein:

a. said second unidirectional conductive means is a diode means and said high value resistor means is also connected in parallel with said diode means to complete reestablishment of said charge as aforesaid.

4. An electric organ stimulator comprising:

a. terminals adapted to be connected to a d-c source, b. a capacitor and a first output terminal connected to one side thereof and adapted to be connected to an organ load, c. a second output terminal connected to a d-c source terminal and adapted to be connected to an organ load, d. diode means and a controllable switch means having load terminals and a control means, said diode means and said load terminals being connected in series between said d-c source terminals, said control means selectively controlling conduction between said load terminals in response to a control signal on said control means for a predetermined interval when stimulation of an organ is desired, e. means for applying a control signal to said control means, f. the other side of said capacitor being connected to a point between said diode means and controllable switch means, whereby to enable said capacitor to charge to an initial state from said source through said diode means when said switch means is nonconductive, g. a high value resistor means connected between the d-c source terminal to which said diode means is connected and said other side of said capacitor, said resistor thereby shunting said diode means, h. conduction of said controllable switch means in response to said control signal causing current flow through said capacitor and between said organ load output terminals to thereby alter the initial state of charge on said capacitor rapidly, termination of said signal being followed by altered current flow through said diode, said capacitor and between said organ load terminals to substantially reestablish the initial state of charge on said capacitor rapidly, reestablishment of said charge being completed by ensuing conduction through said high value resistor means.

5. The stimulator in accordance with claim 4 including:

a. a resistor means connected in series with said diode, said resistor means having a substantially lower value than said high value resistor means.

6. An electric organ stimulator compRising:

a. terminals which are adapted to be connected to a d-c source, b. output terminals adapted to be connected to an organ, c. a capacitor having one and another sides the one of which is connected to one of said output terminals, d. first and second unidirectionally conductive means, the first of said conductive means being connected between one of said source terminals and said other capacitor side and the second of said conductive means being connected between said other capacitor side and another of said source terminals, said conductive means being connected in series with each other between said d-c source terminals, the other of said output terminals being connected to said one source terminal, e. at least one of said unidirectionally conductive means having a control means for selectively controlling said one conductive means to conduct in response to a signal on said control means, means for applying a control signal to said control means to cause said one conductive means to conduct for a predetermined interval at a time when an organ is to be stimulated, conduction by said one conductive means causing current flow in one direction across said output terminals and through said capacitor to thereby alter the initial charge on said capacitor, f. said other conductive means responding to said one conductive means conducting by remaining substantially nonconducting, and said other conductive means responding to said one conductive means terminating conduction by immediately conducting to cause current flow in an opposite direction across said output terminals and through said capacitor to thereby reestablish the initial state of charge on said capacitor, g. means for sensing the appearance of natural organ signals on said output terminals, h. pulse signal generator means controlled by said sensing means to produce said control signal in response to said sensing means sensing no natural signal for a predetermined interval, and i. high value resistor means connected between said one source terminal and to said capacitor, said resistor means continuing to conduct after said second conductive means stops conducting whereby to complete charging said capacitor to its initial state.

7. The invention set forth in claim 6 wherein:

a. said first and second unidirectionally conductive means are transistor means each having two load terminals and a control terminal, b. a diode means connected between said other side of said capacitor means, one of said load terminals of said first transistor means and said diode means also being jointly connected between one of said load terminals of said second transistor means and said control terminal of said second transistor means whereby to establish said second transistor control terminal and its one said load terminal at substantially the same potential when said first transistor means conducts to thereby prevent said second transistor means from conducting upon occurrence of said control signal, the other of said load terminals of said second transistor means being connected to one d-c source terminal and the other of said load terminals of said first transistor means being connected to another of said d-c source terminals.

8. The invention set forth in claim 7 wherein:

a. said transistor means each have an emitter and a collector comprising said load terminals and a base terminal comprising said control terminal, b. said second transistor having its collector connected to said another source terminal and its emitter connected to the anode of the diode means, c. said first transistor means having its collector connected to the cathode of said diode means and its emitter connected to said one of said source terminals, d. the said other side of said capacitor being connected to said anode of the diode means, e. means for applying control signals to said control terminal of said first transistor means said signals being applied in a sequence correspondIng with the desired responses of the organ, the said first transistor responding to said signals by conducting and thereby discharging said capacitor sufficiently to stimulate the organ after which said second transistor means conducts in response to termination of conduction by said first transistor means to recharge said capacitor to its initial state.