Method and apparatus for diaphragmatic pacing

• US 6,415,183 B1
• Filed: 12/09/1999
• Issued: 07/02/2002
• Est. Priority Date: 12/09/1999
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Kadhiresan, Veerichetty, Scheiner, Avram
• Primary Examiner(s): Getzow, Scott M.
• Application Number:
  US09/456,879
• Time in Patent Office: 936 Days
• Field of Search: 607/9, 607/42
• US Class Current: 607/42
• CPC Class Codes: A61N 1/3601 of respiratory organs
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence

Abstract

A diaphragmatic pacing system and method. The method includes monitoring a signal representing a patient'"'"'s respiratory activity, and delivering an electric stimulus from a lead to the phrenic nerve when the signal indicates that the respiratory activity is below a predetermined level. Physiological state information, such as the respiration activity or minute ventilation, is sensed using the implanted lead and the method delivers an output based on such input. Another embodiment provides concurrent sensing and pacing of heart and diaphragm using a single implanted pulse generator. The implantable system includes at least one lead and a signal processing circuit coupled to the lead. The signal processing circuit processes a signal representative of a respiratory activity. A controller coupled to the signal processing circuit analyzes the signal and when the signal indicates a need for respiratory therapy the controller outputs a controller signal. An output circuit coupled to the controller, for delivering a pulse in response to the controller signal, the pulse having an amplitude high enough to stimulate a phrenic nerve.

Claims

1. A method, comprising:

delivering an electric stimulus from a lead situated within a body to a phrenic nerve at a controlled rate, wherein the electric stimulus is delivered in a region proximate a wall of a heart, wherein the electric stimulus is delivered from an electrode on the lead, the electrode being located on or within the heart.

2. The method of claim 1, wherein the lead comprises a cardiac rhythm management lead.

3. The method of claim 1, wherein the controlled rate is determined by analyzing whether a signal representing a respiratory state indicates a need for the electrical stimulus.

4. A method, comprising:

delivering an electric stimulus from a lead situated within a body to a phrenic nerve at a controlled rate, wherein the electric stimulus is delivered in a region proximate a wall of a heart, wherein the lead is situated along a lateral wall of a heart.

5. The method of claim 4, wherein the lead comprises:

a cardiac rhythm management lead.

6. The method of claim 4, wherein the controlled rate is determined by a method comprising:

analyzing whether a signal representing a respiratory state indicates a need for the electrical stimulus.

7. The method of claim 6, wherein the respiratory state is a patient'"'"'s chest wall motion.

8. A method, comprising:

delivering an electric stimulus from a lead situated within a body to a phrenic nerve at a controlled rate, wherein the electric stimulus is delivered in a region proximate a wall of a heart, wherein the controlled rate is a asynchronous mode rate.

9. A method, comprising:

delivering an electric stimulus from a lead situated within a body to a phrenic nerve at a controlled rate, the electric stimulus being delivered in a region proximate a wall of a heart, wherein the controlled rate is determined by analyzing whether a signal representing a patient'"'"'s minute ventilation indicates a need for the electrical stimulus.

10. A method, comprising:

monitoring a signal representing a patient'"'"'s respiratory activity; and

delivering an electric stimulus from a lead to a phrenic nerve when the signal indicates that the respiratory activity is below a predetermined level, wherein the electric stimulus is delivered in a region proximate to where the phrenic nerve runs along a wall of a heart of the patient.

11. The method of claim 10, wherein the lead is situated in a superior vena cava.

12. The method of claim 10, wherein the lead is situated along a lateral wall of a heart.

13. The method of claim 10, wherein monitoring a signal comprises:

rectifying the signal;

applying a low pass filter to the signal; and

calculating a decay time constant of the signal.

14. The method of claim 13, further comprising

analyzing whether the decay time constant is below a preset level;

and

analyzing whether an amplitude of the signal is below a preset level.

15. The method of claim 10, wherein the respiratory activity comprises a chest wall motion.

16. The method of claim 10, wherein the respiratory activity comprises a minute ventilation.

17. The method of claim 10, further comprising increasing the amplitude of the electric stimulus if the respiratory activity does not increase after the electric stimulus has been delivered.

18. A method for pacing a heart and a diaphragm, comprising:

analyzing a first signal which indicates whether the heart needs pacing and analyzing a second signal which indicates whether the diaphragm needs pacing;

delivering a first electric stimulus at a first controlled rate to pace the heart when the first signal indicates a need for heart pacing; and

delivering a second electric stimulus at a second controlled rate to pace the diaphragm when the second signal indicates a need for diaphragmatic pacing.

19. The method of claim 18, wherein delivery is from a single pulse generator.

20. The method of claim 18, wherein the first electric stimulus is at a level higher than a heart pacing threshold and lower than a diaphragm pacing threshold, and the second electric stimulus is higher than a diaphragm pacing threshold.

21. The method of claim 18, wherein the first electric stimulus and the second electric stimulus are delivered from the same lead as each other.

22. The method of claim 21, further comprising synchronizing the delivery of the first electric stimulus and the second electric stimulus.

23. A method for heart and diaphragmatic pacing, comprising:

monitoring a first signal representing a patient'"'"'s respiratory activity;

monitoring a second signal representing a patient'"'"'s heart activity;

delivering a first electric stimulus to the phrenic nerve at a first controlled rate when the signal indicates that the respiratory activity is below a predetermined level; and

delivering a second electric stimulus to the heart at a second controlled rate when the signal indicates that the heart activity is below a predetermined level.

24. The method of claim 23, wherein the first electric stimulus is delivered using field steering.

25. The method of claim 23, wherein the first electric stimulus is in the constant voltage range 0.2 volts to 14 volts at a duration of 0.2 to 12 milliseconds, and the second stimulus is in the constant voltage range 0.1 volts to 4 volts at a duration of 0.1 to 2 milliseconds.

26. The method of claim 23, further comprising increasing the amplitude of the first electric stimulus if the respiratory activity does not increase after the first electric stimulus has been delivered.

27. A system, comprising:

at least one lead having a plurality of electrodes;

a signal processing circuit coupled to each of the at least one leads, the signal processing circuit processes a signal representative of a respiratory activity;

a controller coupled to the signal processing circuit, the controller analyzes the signal, when the signal indicates a need for respiratory therapy the controller outputs a controller signal; and

an output circuit coupled to the controller, the output circuit delivers a pulse in response to the controller signal, the pulse having an amplitude high enough to stimulate a phrenic nerve, wherein the pulse is in the constant voltage range 0.2 volts to 14 volts at a duration of approximately 0.2 to 12 milliseconds.

28. The system of claim 27, wherein the lead comprises a cardiac rhythm management lead.

29. The system of claim 27, wherein the controller increases the amplitude of the pulse if the respiratory activity does not increase after the pulse has been delivered.

30. The system of claim 27, wherein the signal processing circuit comprises:

a rectifying circuit for rectifying the signal;

a low pass filter circuit for applying a low pass filter to the signal; and

a circuit for calculating a decay time constant of the signal.

31. The system of claim 30, wherein the controller comprises:

a means for analyzing whether the decay time constant is below a preset level; and

a means for analyzing whether an amplitude of the signal is below a preset level.

32. A system, comprising:

at least one lead having a plurality of electrodes;

a signal processing circuit coupled to each of the at least one leads, the signal processing circuit processes a first signal representative of a respiratory activity, the signal processing circuit senses a second signal representative of a cardiac activity;

a controller coupled to the signal processing circuit, the controller analyzes the first signal and the second signal, when the first signal indicates a need for respiratory therapy the controller outputs a first controller signal, when the first signal does not indicate a need for respiratory therapy and the second signal indicates a need for cardiac therapy the controller outputs a second controller signal; and

an output circuit coupled to the controller, the output circuit delivers a first pulse in response to the first controller signal, the first pulse having an amplitude high enough to stimulate a phrenic nerve, the output circuit delivers a second pulse in response to the second controller signal, the second pulse having an amplitude high enough to pace a heart but not high enough to stimulate a phrenic nerve.

33. The system of claim 32, wherein when the controller outputs a second signal, the controller output rate is dependent on the first signal representative of a patient'"'"'s respiratory activity.

34. A method for heart and diaphragmatic pacing, comprising:

monitoring a first signal representing a patient'"'"'s respiratory activity;

monitoring a second signal representing a patient'"'"'s heart activity;

delivering a first electric stimulus to a phrenic nerve at a first controlled rate when the first signal indicates that the patient'"'"'s respiratory activity is below a predetermined level; and

delivering a second electric stimulus to a heart at a second controlled rate when the second signal indicates that the patient'"'"'s heart activity is below a predetermined level,

wherein the first electric stimulus is in the constant voltage range 0.2 volts to 14 volts at a duration of 0.2 to 12 milliseconds, and the second stimulus is in the constant voltage range 0.1 volts to 4 volts at a duration of 0.1 to 2 milliseconds.

35. The method of claim 34, wherein the first electric stimulus is delivered using field steering.

36. The method of claim 34, further comprising increasing the amplitude of the first electric stimulus if the respiratory activity does not increase after the first electric stimulus has been delivered.