PRESSURE-DRIVEN INTERMITTENT PACING THERAPY

• US 20100069989A1
• Filed: 08/06/2009
• Published: 03/18/2010
• Est. Priority Date: 08/12/2008
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Hamann, Jason J., Shuros, Allan C., Arcot-Krishnamurthy, Shantha, Shipley, Robert
• Granted Patent: US 8,401,642 B2
• Time in Patent Office: Days
• US Class Current: 607/18
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/36564 controlled by blood pressure
• CPC Class Codes: A61N 1/36571 controlled by blood flow rate, e.g. blood velocity or cardiac output
• 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 1/3688 configured for switching the pacing mode, e.g. from AAI to DDD

Abstract

Cardioprotective pre-excitation pacing may be applied to stress or de-stress a particular myocardial region delivering of pacing pulses in a manner that causes a dyssynchronous contraction. Such dyssynchronous contractions are responsible for the desired cardioprotective effects of pre-excitation pacing but may also be hazardous. Described herein is a method and system that uses measures of a patient'"'"'s physiological response to ventricular dyssynchrony to control the duty cycles of intermittent pre-excitation pacing.

Claims

1. A cardiac device, comprising:

one or more pacing channels for delivering pacing pulses to one or more myocardial sites;

a controller programmed to operate the device in either a normal operating mode or an intermittent pacing therapy (IPT) mode;

wherein, in the IPT mode, the controller is programmed to deliver paces to the one or more myocardial sites using a pacing mode that results in some degree of ventricular dyssynchrony as compared with the normal operating mode;

a sensor for measuring a hemodynamic variable affected by IPT;

wherein the controller is programmed to;

establish timed duty cycles for delivering IPT;

measure a baseline value for the hemodynamic variable during normal sinus rhythm when no IPT is being delivered;

switch to the IPT mode as scheduled by the timed duty cycle if the hemodynamic variable is stable and within a specified range of the baseline value;

continue to monitor the hemodynamic variable during delivery of IPT and, if the hemodynamic variable is found to deviate from its baseline value by a predetermined amount, switch to the normal mode; and

,

continue to monitor the hemodynamic variable during the normal mode and, when the hemodynamic variable returns to a value that is within a predetermined range of the baseline value, switch to IPT mode if the duty cycle has not expired.

2. The device of claim 1 wherein the controller is programmed to first determine whether a specified stability criterion for the hemodynamic variable is met before terminating or initiating IPT.

3. The device of claim 1 wherein the sensor is a blood pressure sensor.

4. The device of claim 1 wherein the sensor is an impedance sensor for measuring stroke volume.

5. The device of claim 1 wherein the sensor includes an impedance sensor for measuring stroke volume and a cardiac sensing channel for measuring heart rate in order to derive cardiac output as the hemodynamic variable.

6. The device of claim 3 wherein the controller is further programmed to:

determine when the measured blood pressure stabilizes at an IPT-induced lower level after IPT is initiated, at which point the IPT is turned off and the controller switches to the normal mode; and

,

reinitiate IPT if the current duty cycle has not timed out when the measured blood pressure returns to the baseline value and stabilizes.

7. The device of claim 3 wherein the controller is further programmed to switch from the IPT mode to the normal mode if the blood pressure rises to a predetermined value within a specified range of the baseline value during delivery of IPT as a result of a systemic reflex response.

8. The device of claim 4 wherein the controller is further programmed to switch from the IPT mode to the normal mode if the stroke volume rises to a predetermined value within a specified range of the baseline value during delivery of IPT as a result of a systemic reflex response.

9. The device of claim 5 wherein the controller is further programmed to switch from the IPT mode to the normal mode if the cardiac output rises to a predetermined value within a specified range of the baseline value during delivery of IPT as a result of a systemic reflex response.

10. The device of claim 1 wherein the controller is further programmed to discontinue delivery of IPT if the hemodynamic variable is out of a predetermined range considered safe during a predetermined number of IPT duty cycles.

11. A method for operating a cardiac device, comprising:

delivering pacing pulses to one or more myocardial sites;

operating the device in either a normal operating mode or an intermittent pacing therapy (IPT) mode;

in the IPT mode, delivering paces to the one or more myocardial sites using a pacing mode that results in some degree of ventricular dyssynchrony as compared with the normal operating mode;

measuring a hemodynamic variable affected by IPT;

establishing timed duty cycles for delivering IPT;

measuring a baseline value for the hemodynamic variable during normal sinus rhythm when no IPT is being delivered.

switching to the IPT mode as scheduled by the timed duty cycle if the hemodynamic variable is stable and within a specified range of the baseline value;

continuing to monitor the hemodynamic variable during delivery of IPT and, if the hemodynamic variable is found to deviate from its baseline value by a predetermined amount, switching to the normal mode; and

,

continuing to monitor the hemodynamic variable during the normal mode and, when the hemodynamic variable returns to a value that is within a predetermined range of the baseline value, switching to IPT mode if the duty cycle has not expired.

12. The method of claim 11 further comprising first determining whether a specified stability criterion for the hemodynamic variable is met before terminating or initiating IPT.

13. The method of claim 11 wherein the sensor is a blood pressure sensor.

14. The method of claim 11 wherein the sensor is an impedance sensor for measuring stroke volume.

15. The method of claim 11 wherein the sensor includes an impedance sensor for measuring stroke volume and a cardiac sensing channel for measuring heart rate in order to derive cardiac output as the hemodynamic variable.

16. The method of claim 13 further comprising:

determining when the measured blood pressure stabilizes at an IPT-induced lower level after IPT is initiated, at which point turning IPT off and switching to the normal mode; and

,

reinitiating IPT if the current duty cycle has not timed out when the measured blood pressure returns to the baseline value and stabilizes.

17. The method of claim 13 further comprising switching from the IPT mode to the normal mode if the blood pressure rises to a predetermined value within a specified range of the baseline value during delivery of IPT as a result of a systemic reflex response.

18. The method of claim 14 further comprising switching from the IPT mode to the normal mode if the stroke volume rises to a predetermined value within a specified range of the baseline value during delivery of IPT as a result of a systemic reflex response.

19. The method of claim 15 further comprising switching from the IPT mode to the normal mode if the cardiac output rises to a predetermined value within a specified range of the baseline value during delivery of IPT as a result of a systemic reflex response.

20. The method of claim 11 further comprising discontinuing delivery of IPT if the hemodynamic variable is out of a predetermined range considered safe during a predetermined number of IPT duty cycles.