Atrial tracking recovery to restore cardiac resynchronization therapy in dual chamber tracking modes

• US 20040210264A1
• Filed: 04/21/2003
• Published: 10/21/2004
• Est. Priority Date: 04/21/2003
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Kleckner, Karen J., Betzold, Robert A., Lynn, Thomas G. Jr.
• Granted Patent: US 6,889,083 B2
• Time in Patent Office: Days
• US Class Current: 607/25
• 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 1/3684 for stimulating the heart at multiple sites of the ventricle or the atrium
• CPC Class Codes: A61N 1/36843 Bi-ventricular stimulation

Abstract

A feature named “atrial tracking recovery” (ATR) provides a means of restoring delivery of cardiac pacing therapy upon identification of an AR-VS pattern of cardiac activity. The present invention incorporates a method of monitoring such patterns to determine if they are terminable. Once the AR-VS pattern is identified, according to the present invention the PVARP is shortened to allow sensing of the atrial event, which previously was unable to initiate an SAV interval. Subsequent SAV intervals are shortened until an atrial event is sensed so that a ventricular pacing stimulus is delivered after the SAV interval expires. Since the SAV interval is normally programmed to an interval that is shorter than the intrinsic conduction time, ventricular pacing stimulus is provided after the SAV ends, thereby effectively restoring delivery of a ventricular pacing modality such as cardiac resynchronization therapy (CRT).

Claims

1. A method of terminating a non-pacing AR-VS cardiac sequence and re-establishing a preferred AP-VS pacing sequence, comprising:

a) monitoring an atrial chamber and at least one ventricular chamber for delivery of a pacing therapy and for sensing of intrinsic depolarization activity and, in the event that a series of atrial refractory events (AR) occur during an initial PVARP resulting in the sensing of intrinsic depolarizations of the at least one ventricular chamber;

b) iteratively reducing the duration of the initial PVARP for a predetermined number of consecutive cardiac cycles until an intrinsic atrial event occurs following the PVARP and is sensed (AS) or a cardiac pattern other than a AR-VS pattern occurs;

c) delivering a ventricular pacing stimulus to the at least one ventricular chamber at the expiration of a sensed atrioventricular (SAV) delay interval; and

d) extending the duration of the initial PVARP for at least a subsequent cardiac cycle.

2. A method according to claim 1, further comprising:

e) returning to step a).

3. A method according to claim 1, wherein the series of atrial refractory events (AR) that occur during the initial PVARP resulting in the sensing of intrinsic depolarization of the at least one ventricular chamber comprises at least five consecutive atrial refractory events (AR).

4. A method according to claim 1, wherein the series of atrial refractory events (AR) that occur during an initial PVARP resulting in the sensing of intrinsic depolarization of the at least one ventricular chamber comprises at least eight consecutive atrial refractory events (AR).

5. A method according to claim 2, wherein at step e) in lieu of returning to step a), the following steps are performed:

if an upper rate hold-off ventricular pace occurs due to an AV interval duration being longer than an operating SAV interval, and a maximum interval calculated in milliseconds based on a just prior cardiac cycle is less than an operating PVARP, declaring termination of the AR-VS pattern, wherein the maximum interval further comprises an A-A interval less a A-V interval less a 50 millisecond constant.

6. A method according to claim 2, wherein at step e) in lieu of returning to step a), the following steps are performed:

if an upper rate hold-off ventricular pace occurs due to an AV interval duration being longer than an operating SAV interval, and a maximum interval calculated in milliseconds based on a just prior cardiac cycle is greater than or equal to an operating PVARP, declaring termination of the AR-VS pattern, wherein the maximum interval further comprises the greater of an A-A interval less a A-V interval less a 50 millisecond constant or a post ventricular atrial blanking (PVAB) period;

setting the operating PVARP to a maximum value; and

returning to step b).

7. A method according to claim 1, wherein the initial PVARP is a maximum duration PVARP.

8. A method according to claim 1, wherein the initial PVARP is a previously manually programmed PVARP.

9. A method according to claim 1, wherein extending the initial PVARP comprises extending the initial PVARP to a value existing prior to any adjustment of the initial PVARP pursuant to step b).

10. An apparatus for terminating a non-pacing AR-VS cardiac sequence and re-establishing a preferred AP-VS cardiac pacing sequence, comprising:

a) means for monitoring an atrial chamber and at least one ventricular chamber for delivery of a pacing therapy and for sensing of intrinsic depolarization activity and, in the event that a series of atrial refractory events (AR) occur during an initial PVARP resulting in the sensing of intrinsic depolarizations of the at least one ventricular chamber;

b) means for iteratively reducing the duration of the initial PVARP for a predetermined number of consecutive cardiac cycles until an intrinsic atrial event occurs following the PVARP and is sensed (AS) or a cardiac pattern other than a AR-VS pattern occurs;

c) means for delivering a ventricular pacing stimulus to the at least one ventricular chamber at the expiration of a sensed atrioventricular (SAV) delay interval; and

d) means for extending the duration of the initial PVARP for at least a subsequent cardiac cycle.

11. A computer readable medium for storing instructions for performing a method, comprising:

a) instructions for monitoring an atrial chamber and at least one ventricular chamber for delivery of a pacing therapy and for sensing of intrinsic depolarization activity and, in the event that a series of atrial refractory events (AR) occur during an initial PVARP resulting in the sensing of intrinsic depolarizations of the at least one ventricular chamber;

b) instructions for iteratively reducing the duration of the initial PVARP for a predetermined number of consecutive cardiac cycles until an intrinsic atrial event occurs following the PVARP and is sensed (AS) or a cardiac pattern other than a AR-VS pattern occurs;

c) instructions for delivering a ventricular pacing stimulus to the at least one ventricular chamber at the expiration of a sensed atrioventricular (SAV) delay interval; and

d) instructions for extending the duration of the initial PVARP for at least a subsequent cardiac cycle.

12. A method according to claim 11, further comprising:

e) instructions for returning to step a).

13. A method according to claim 11, wherein the series of atrial refractory events (AR) that occur during the initial PVARP resulting in the sensing of intrinsic depolarization of the at least one ventricular chamber comprises at least five consecutive atrial refractory events (AR).

14. A method according to claim 11, wherein the series of atrial refractory events (AR) that occur during an initial PVARP resulting in the sensing of intrinsic depolarization of the at least one ventricular chamber comprises at least eight consecutive atrial refractory events (AR).

15. A method according to claim 12, wherein at step e) in lieu of instructions for returning to step a), the following steps are performed:

if an upper rate hold-off ventricular pace occurs due to an AV interval duration being longer than an operating SAV interval, and a maximum interval calculated in milliseconds based on a just prior cardiac cycle is less than an operating PVARP, instructions for declaring termination of the AR-VS pattern, wherein the maximum interval further comprises an A-A interval less an A-V interval less a 50 millisecond constant.

16. A method according to claim 12, wherein at step e) in lieu of instructions for returning to step a), the following steps are performed:

if an upper rate hold-off ventricular pace occurs due to an AV interval duration being longer than an operating SAV interval, and a maximum interval calculated in milliseconds based on a just prior cardiac cycle is greater than or equal to an operating PVARP,

instructions for declaring termination of the AR-VS pattern, wherein the maximum interval further comprises an A-A interval less an A-V interval less a 50 millisecond constant;

instructions for setting the operating PVARP to a maximum value; and

returning to step b).

17. A method according to claim 11, wherein the initial PVARP is a maximum duration PVARP.

18. A method according to claim 11, wherein the initial PVARP is a previously manually programmed PVARP.

19. A method according to claim 11, wherein extending the initial PVARP comprises extending the initial PVARP to a value existing prior to any adjustment of the initial PVARP pursuant to step b).

20. A method of terminating a cardiac pacing sequence of AR-VS and re-establishing a preferred cardiac pacing sequence of AP-VS, comprising:

a) monitoring an atrial chamber and at least one ventricular chamber for a predetermined plurality of cardiac cycles to sense intrinsic depolarization activity and deliver a pacing therapy and, in the event that an atrial refractory event (AR) occurs during an initial PVARP resulting in the sensing of intrinsic depolarization of the at least one ventricular chamber (VS) and a set of preset criteria are met for predetermined plurality of cardiac cycles, transition to step b), wherein said preset criteria comprise at least a majority of the following;

a present pacing mode is an atrial tracking pacing mode,

a current ventricular event is a sense event (VS),

a single atrial refractory event occurred during an immediately prior PVARP,

an immediately prior atrial interval was no more than 50 ms different than a just-preceding atrial interval,

an immediately prior atrial interval was greater than 50 ms than an upper tracking rate,

an immediately prior atrial interval was greater than the magnitude of an operating SAV interval added to an operating PVARP,

an interval from a just prior ventricular event to a just prior atrial event (or a just prior VS-AR interval) is greater than a PVAB;

b) iteratively reducing the duration of the initial PVARP until an intrinsic atrial event is sensed (AS) or a pattern other than an AR-VS pattern occurs;

c) delivering a ventricular pacing stimulus to the at least one ventricular chamber at the expiration of an atrioventricular delay interval; and

d) extending the duration of the initial PVARP.