Implantable cardiac device and method for reduced phrenic nerve stimulation

• US 20060241711A1
• Filed: 04/26/2005
• Published: 10/26/2006
• Est. Priority Date: 04/26/2005
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Sathaye, Alok S.
• Granted Patent: US 7,392,086 B2
• Time in Patent Office: Days
• US Class Current: 607/28
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence
• CPC Class Codes: A61N 1/3684 for stimulating the heart at multiple sites of the ventricle or the atrium
• CPC Class Codes: A61N 1/36842 Multi-site stimulation in the same chamber
• CPC Class Codes: A61N 1/36843 Bi-ventricular stimulation
• CPC Class Codes: A61N 1/3712 Auto-capture, i.e. automatic adjustment of the stimulation threshold

Abstract

Methods and devices for reducing phrenic nerve stimulation of cardiac pacing systems involve delivering a pacing pulse to a ventricle of a heart. A transthoracic impedance signal is sensed, and a deviation in the signal resulting from the pacing pulse may be used to determine phrenic nerve stimulation. Methods may further involve detecting the phrenic nerve stimulation from the pacing pulse by delivering two or more pacing pulse to the ventricle of the heart, and determining a temporal relationship. A pacing vector may be selected from the two or more vectors that effects cardiac capture and reduces the phrenic nerve stimulation. A pacing voltage and/or pulse width may be selected that provides cardiac capture and reduces the phrenic nerve stimulation. In other embodiments, a pacing pulse width and a pacing voltage may be selected from a patient'"'"'s strength-duration curve that effects cardiac capture and reduces the phrenic nerve stimulation.

Claims

1. A method of cardiac pacing, comprising:

delivering a pacing pulse to a ventricle of a heart using one of a plurality of vectors;

sensing a transthoracic impedance signal;

detecting a deviation in the transthoracic impedance signal following the delivery of the pacing pulse; and

determining the presence of phrenic nerve stimulation resulting from the pacing pulse based on the deviation in the transthoracic impedance signal.

2. The method of claim 1, wherein detecting the phrenic nerve stimulation from the pacing pulse comprises:

delivering a plurality of pacing pulse to the ventricle of the heart; and

determining a temporal relationship between the transthoracic impedance signal and the plurality of pacing pulses.

3. The method of claim 1, comprising selecting a pacing vector from the plurality of vectors that effects cardiac capture and reduces the phrenic nerve stimulation.

4. The method of claim 1, comprising selecting a pacing voltage that provides cardiac capture and reduces the phrenic nerve stimulation.

5. The method of claim 1, comprising selecting a pacing pulse width that provides cardiac capture and reduces the phrenic nerve stimulation.

6. The method of claim 1, comprising evaluating the transthoracic impedance signal for an inspiration event within an evaluation window defined by the pacing pulse and about 500 milliseconds following the pacing pulse.

7. The method of claim 1, comprising selecting a pacing pulse width and a pacing voltage from a patients strength-duration curve that effects cardiac capture and reduces the phrenic nerve stimulation.

8. The method of claim 1, comprising:

transmitting information associated with the sensed cardiac signal and the sensed transthoracic impedance signal to a patient-external device;

receiving pacing signal information from the patient-external device; and

altering the pacing pulse based on the received pacing signal information.

9. A medical device, comprising:

a plurality of electrodes electrically coupled to a heart;

a pulse delivery circuit configured to deliver a pacing pulse to a heart using the plurality of electrodes;

a transthoracic impedance sensor configured to sense a transthoracic impedance signal; and

a control circuit coupled to the sensing circuit and the transthoracic impedance sensor, the control circuit configured to determine the presence of phrenic nerve stimulation resulting from the pacing pulse based on a deviation in the transthoracic impedance signal.

10. The device of claim 9, wherein the control circuit is configured to provide pacing pulse parameters to the pulse delivery circuit that reduce phrenic nerve stimulation while maintaining cardiac capture.

11. The device of claim 9, wherein the control circuit is configured to determine one or more pacing pulse parameters that reduce phrenic nerve stimulation while maintaining cardiac capture.

12. The device of claim 9, wherein a signal processor is provided in a patient-external device or system, the signal processor and the control circuit coupled to respective communication devices to facilitate wireless communication between the signal processor and the control circuit.

13. The device of claim 9, wherein a signal processor is provided in a network server system, the signal processor and the control circuit coupled to respective communication devices to facilitate wireless communication between the signal processor and the control circuit.

14. The device of claim 9, wherein the control circuit is configured to select a pacing vector that reduces the phrenic nerve stimulation while maintaining cardiac capture.

15. A medical device, comprising:

means for sensing an electrophysiologic signal from a heart;

means for delivering a pacing pulse to the heart;

means for detecting a cardiac signal following the pacing pulse;

means for sensing a transthoracic impedance signal; and

means for detecting a phrenic nerve stimulation from the pacing pulse using the transthoracic impedance signal.

16. The device of claim 15, comprising means for determining a temporal relationship between the transthoracic impedance signal and the electrophysiologic signal.

17. The device of claim 15, comprising means for selecting a pacing vector that effects cardiac capture and reduces the phrenic nerve stimulation.

18. The device of claim 15, comprising means for selecting a pacing voltage that effects cardiac capture and reduces the phrenic nerve stimulation.

19. The device of claim 15, comprising means for selecting a pacing pulse width that effects cardiac capture and reduces the phrenic nerve stimulation.

20. The device of claim 15, comprising means for transmitting information associated with the sensed electrophysiologic signals and the sensed transthoracic impedance signal to a patient-external device.