SYSTEMS AND METHODS FOR POSTEXTRASYSTOLIC POTENTIATION USING ANODIC AND CATHODIC PULSES GENERATED BY AN IMPLANTABLE MEDICAL DEVICE

• US 20140107719A1
• Filed: 10/11/2012
• Published: 04/17/2014
• Est. Priority Date: 10/11/2012
• Status: Abandoned Application

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Bornzin, Gene A., Ryu, Kyungmoo
• Application Number:
  US13/649,657
• Publication Number:
  US 20140107719A1
• Time in Patent Office: Days
• US Class Current: 607/9
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

Techniques are provided for use with implantable medical devices to deliver paired or coupled postextrasystolic potentiation (PESP) pacing using split or bifurcated anodic and cathodic pulses. In a paired pacing example, a single-phase anodic pulse is delivered by the device that has sufficient amplitude to depolarize and contract myocardial tissue. During or just following a subsequent relative refractory period, a single-phase cathodic stimulation pulse is delivered that has sufficient amplitude to depolarize but not contract myocardial tissue, i.e., the cathodic pulse provides for PESP. In a coupled pacing example, the single-phase anodic pulse is delivered during or just following the relative refractory period of a first cardiac cycle; whereas the single-phase cathodic pulse is delivered during or immediately following the relative refractory period of the next consecutive cardiac cycle.

Claims

1. A method for use with an implantable cardiac stimulation device equipped to deliver postextrasystolic potentiation (PESP) pacing, the method comprising:

generating a single-phase primary stimulation pulse for delivery to the heart of the patient sufficient to depolarize myocardial tissue, the single-phase primary pulse being one of anodic or cathodic; and

generating a single-phase secondary stimulation pulse for delivery to the heart of the patient at a time sufficient to generate closely spaced dual-depolarization, the secondary pulse being opposite in polarity to the primary pulse and being configured to achieve PESP.

2. The method of claim 1 wherein the single-phase secondary stimulation pulse is delivered during a relative refractory period.

3. The method of claim 2 wherein the single-phase secondary stimulation pulse is delivered immediately following a relative refractory period.

4. The method of claim 3 wherein the single-phase secondary stimulation pulse is delivered within 50 milliseconds from the end of the relative refractory period.

5. The method of claim 1 wherein the single-phase primary pulse is an anodic pulse and the single-phase secondary pulse is a cathodic pulse.

6. The method of claim 5 wherein the single-phase primary pulse and the single-phase secondary pulse have about equal voltages and about equal durations.

7. The method of claim 6 wherein the single-phase primary pulse has an pulse amplitude of about 2 volts and a duration of about 1 millisecond (ms) and wherein the single-phase secondary pulse also has a pulse amplitude of about 2 volts and a duration of about 1 ms.

8. The method of claim 5 further including a preliminary step of setting pulse amplitudes and pulse widths for the single-phase primary pulse and for the single-phase secondary pulse.

9. The method of claim 8 wherein the preliminary step of setting the pulse amplitudes and pulse widths comprises:

determining strength duration curves for the primary anodic pulse and for the secondary cathodic pulse that relate pulse amplitudes as a function of pulse width and combined voltages;

setting a combined voltage to a starting voltage;

selecting a starting pulse width for the primary anodic pulse; and

iteratively setting the pulse width of the secondary cathodic pulse by incrementally increasing the width of the secondary cathodic pulse while holding the combined voltage substantially constant and while determining whether corresponding pulse amplitudes for the primary pulse and the secondary pulse obtained from the strength duration curves both exceed a minimum target voltage by a predetermined safety margin.

10. The method of claim 9 wherein, if the pulse amplitudes do not both exceed the target voltage by the predetermined safety margin, incrementally increasing the pulse width of the primary anodic pulse up to a maximum programmable width while repeating the step of iteratively setting the pulse width of the secondary cathodic pulse.

11. The method of claim 10 wherein, if the primary anodic pulse has reached its maximum programmable width without resulting amplitudes of the primary anodic pulse and the secondary cathodic pulse both exceeding the target voltage by the predetermined safety margin, increasing the combined voltage above the starting voltage and repeating the step of iteratively setting the pulse width of the secondary cathodic pulse.

12. The method of claim 9 wherein, once the amplitudes of the primary anodic pulse and the secondary cathodic pulse both exceed the target voltage by the predetermined safety margin, delivering pacing using the lowest amplitudes and pulses widths that achieved the predetermined safety margins at the lowest combined voltage.

13. The method of claim 9 wherein the safety margin is 2:

1 as represented as a ratio of pulse amplitude to minimum target voltage.

14. The method of claim 9 wherein the strength duration curves are determined using the Lapicque equation.

15. The method of claim 9 wherein the strength duration curves are represented using one or more of a:

lookup table or a functional equivalent to a lookup table.

16. The method of claim 5 wherein the refractory interval also includes an absolute refractory period prior to the relative refractory period.

17. The method of claim 5 for use with a device equipped to blank a sensing channel during delivery of stimulation pulses and wherein a width of the single-phase primary stimulation pulse and a width of the single-phase secondary PESP pulse are set to reduce an amount of time during which sensing channel blanking is employed.

18. The method of claim 1 wherein the steps of generating the single-phase primary stimulation pulse and generating the single-phase secondary stimulation pulse are performed in response to a paced depolarization in accordance with paired pacing.

19. The method of claim 1 for use with a device having a pacing circuit including a passive recharge resistor and having at least one capacitor and wherein, between generation of the primary pulse and the secondary pulse of opposite polarity, the passive recharge resistor is decoupled from the capacitor to prevent discharge of the capacitor.

20. The method of claim 1 wherein the single-phase primary pulse is a cathodic pulse and the single-phase secondary pulse is an anodic pulse.

21. A system for use with an implantable cardiac stimulation device equipped to deliver postextrasystolic potentiation (PESP) pacing, the system comprising:

a single-phase primary stimulation pulse generator operative to generate a single-phase primary stimulation pulse for delivery to the heart of the patient, the single-phase primary pulse being one of anodic or cathodic;

a single-phase secondary stimulation pulse generator operative to generate a single-phase secondary stimulation pulse for delivery to the heart of the patient at a time sufficient to generate closely spaced dual-depolarization, the single-phase secondary stimulation pulse being opposite in polarity to the primary pulse and configured to achieve PESP.

22. The system of claim 21 further including a strength duration curve-based system operative to set pulse amplitudes and pulse widths for the single-phase primary pulse and for the single-phase secondary pulse based on predetermined strength duration curves for the primary pulse and for the secondary pulse.

23. The system of claim 21 wherein the primary stimulation pulse generator, the refractory period tracking system, and the secondary stimulation pulse generator are components of a paired pacing system operative in response to detection of a paced depolarization.

24. The system of claim 21 wherein the refractory period tracking system and the secondary stimulation pulse generator are components of a coupled pacing system operative in response to detection an intrinsic depolarization.

26. The method of claim 21 wherein the first single-phase stimulation pulse is an anodic pulse and the second single-phase stimulation is a cathodic pulse.

27. The method of claim 22 wherein the first single-phase stimulation pulse is a cathodic pulse and the second single-phase stimulation is an anodic pulse.

25. A method for use with an implantable cardiac stimulation device equipped to deliver postextrasystolic potentiation (PESP) pacing, the method comprising:

detecting a first intrinsic depolarization and tracking a corresponding first refractory interval including a first relative refractory period;

generating a first single-phase stimulation pulse for delivery to the heart of the patient timed relative to the first relative refractory period to generate closely spaced dual-depolarization, the first single-phase stimulation pulse being configured to achieve PESP;

detecting a second intrinsic depolarization and tracking a corresponding second refractory interval including a second relative refractory period; and

generating a second single-phase stimulation pulse for delivery to the heart of the patient timed relative to the second relative refractory period to generate closely spaced dual-depolarization, the second stimulation pulse being opposite in polarity to a polarity of the first stimulation pulse and configured to achieve PESP.

28. A system for use with an implantable cardiac stimulation device equipped to deliver postextrasystolic potentiation (PESP) pacing, the system comprising:

a refractory interval tracking system operative to track refractory intervals within the heart of the patient subsequent to intrinsic depolarization events, the refractory intervals including relative refractory periods; and

an alternating cycle anodic/cathodic pulse generator operative to generate a first single-phase stimulation pulse for delivery to the heart of the patient timed relative to a first relative refractory period sufficient to generate closely spaced dual-depolarization following a first intrinsic depolarization event within a first cardiac cycle and further operative to generate a second single-phase stimulation pulse for delivery to the heart of the patient timed relative to a second relative refractory period following a second intrinsic depolarization event within a second cardiac cycle at a time sufficient to generate another closely spaced dual-depolarization, the first and single-phase stimulation pulses both being configured to achieve PESP.