Defibrillation pacing circuitry

• US 20030088282A1
• Filed: 11/05/2001
• Published: 05/08/2003
• Est. Priority Date: 11/05/2001
• Status: Active Grant

• Current Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Original Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Inventors: Ostroff, Alan H.
• Granted Patent: US 6,952,608 B2
• Time in Patent Office: Days
• US Class Current: 607/5
• CPC Class Codes: A61N 1/362 Heart stimulators heart defibrillators A61N1/39
• CPC Class Codes: A61N 1/3912 Output circuitry therefor, e.g. switches
• CPC Class Codes: A61N 1/39622 Pacing therapy

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.

Claims

1. The apparatus comprising

an H-bridge defibrillator circuit;

and

means switchable into and out of said circuit for causing a constant current to flow through a patient connected to said circuit.

2. The apparatus of claim 1 wherein said means for causing comprises means for imposing a constant voltage across a resistance located in the low side of said circuit.

3. The apparatus of claim 2 wherein said means for imposing comprises a constant voltage source.

4. The apparatus of claim 2 wherein said voltage source applies a constant voltage to a control terminal of a switching device.

5. The apparatus of claim 4 wherein said resistance is located in a leg of said switching device.

6. The apparatus of claim 3 wherein said constant voltage source comprises a digital to analog converter (DAC).

7. The apparatus of claim 6 wherein said constant voltage source further comprises a feedback circuit.

8. The apparatus of claim 4 wherein said constant voltage source comprises a digital to analog converter (DAC).

9. The apparatus of claim 8 wherein said constant voltage source further comprises a feedback circuit.

10. The apparatus of claim 1 wherein said means for causing comprises a resistance connected between a high voltage source and a high side of said defibrillator circuit.

11. The apparatus of claim 10 wherein the value of said resistance is selected to be much larger than the resistance of said patient.

12. The apparatus of claim 10 further including a switch operable to switch said resistance in and out of said circuit.

13. The apparatus of claim 12 further including a high side driver circuit for activating said switch.

14. The apparatus comprising:

circuit means for delivering a defibrillating current pulse to a patient; and

means switchable into and out of connection with said circuit means for causing a constant current to flow through said patient during a period when a current pulse is not being delivered.

15. The apparatus of claim 14 wherein said means for causing comprises means for imposing a constant voltage across a resistance located in a low side of said circuit means.

16. The apparatus of claim 15 wherein said means for imposing comprises a constant voltage source.

17. The apparatus of claim 16 wherein said voltage source applies a constant voltage to a control terminal of a switching device.

18. The apparatus of claim 17 wherein said resistance is located in a leg of said switching device.

19. The apparatus of claim 16 wherein said constant voltage source comprises a digital to analog converter (DAC).

20. The apparatus of claim 19 wherein said constant voltage source further comprises a feedback circuit.

21. The apparatus of claim 17 wherein said constant voltage source comprises a digital to analog converter (DAC).

22. The apparatus of claim 21 wherein said constant voltage source further comprises a feedback circuit.

23. The apparatus of claim 14 wherein said means for causing comprises a resistance connected between a high voltage source and a high side of said defibrillator circuit.

24. The apparatus of claim 23 wherein the value of said resistance is selected to be much larger than the resistance of said patient.

25. The apparatus of claim 23 further including a switch operable to switch said resistance in and out of said circuit.

26. The apparatus of claim 25 further including a high side driver circuit for activating said switch.

27. A method comprising the steps of:

employing a defibrillator circuit to deliver a defibrillating energy pulse to a patient; and

reconfiguring said circuit in response to at least one switching signal to deliver a constant current to said patient.

28. The method of claim 27 wherein said step of reconfiguring comprises switching a resistance into a selected portion of said defibrillator circuit.

29. The method of claim 28 wherein said resistance is switched into a leg of a low side switching device.

30. The method of claim 29 wherein said resistance is switched into series between a high voltage source and a high side of said defibrillator circuit.

31. The method of claim 28 further including the step of applying a constant voltage across said resistance.

32. The method of claim 31 wherein a digital to analog converter is employed in said step of applying a constant voltage.

33. The method of claim 31 wherein a feedback circuit is employed in said step of applying a constant voltage.

34. Electronic circuitry comprising:

a switching device connected in a circuit to assist in sending a current pulse through a patient;

a resistance connected to be switchable in and out of a leg of said switching device; and

a source of constant voltage adapted to be applied across said resistance.

35. The circuit of claim 34 wherein said source of constant voltage comprises a digital to analog converter.

36. The circuit of claim 34 wherein said source of constant voltage comprises a feedback circuit.

37. The circuit of claim 35 wherein said source of constant voltage further comprises a feedback circuit.

38. Electronic circuitry comprising:

a high voltage source;

a switching device connected to assist in sending a current pulse through a patient; and

a resistance switchable into and out of connection between said high voltage source and said switching device and having a value selected to cause a constant current to flow therethrough when said resistance is switched into said connection.

39. The circuitry of claim 38 wherein said high voltage source comprises a capacitor.

40. The circuitry of claim 39 further including a high side driver for controlling the switching of said resistance into and out of said connection.