System and method for arrhythmia discrimination with atrial-ventricular dissociation

• US 7,729,754 B2
• Filed: 10/30/2006
• Issued: 06/01/2010
• Est. Priority Date: 10/30/2006
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Gillberg, Jeffrey M., Jackson, Troy E., Brown, Mark L., Cao, Jian
• Primary Examiner(s): Evanisko; George R
• Assistant Examiner(s): EL-KAISSI, HIBA CARINE
• Application Number:
  US11/554,323
• Publication Number:
  US 20080103404A1
• Time in Patent Office: 1,310 Days
• Field of Search: 607/14, 607/26, 607/4, 607/5, 607/9, 607/17, 600/518, 600/519, 600/515, 600/516
• US Class Current: 600/518
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/3624 occurring in the atrium, i.e. atrial tachycardia
• CPC Class Codes: A61N 1/395 for treating atrial fibrillation
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion

Abstract

Ventricular arrhythmias are monitored and classified based upon various criteria. One criterion is PR dissociation which is determined by comparing the PR interval in a current RR cycle to a median PR value. If the current PR interval varies too far from the median, then dissociation is indicated. Often, there are multiple atrial events in a given RR interval and the PR value has been based upon the last atrial event in the cycle. An algorithm determines whether to use the last atrial event in a cycle or whether an earlier atrial event occurred and would provide a more accurate PR value.

Claims

1. A method of determining PR dissociation comprising:

sensing atrial events (P-waves) and ventricular events (R-waves);

generating a target PR value from a plurality of preceding R-R intervals;

identifying a given R-R interval;

setting a current PR interval for the given R-R interval to a first duration defined as the interval between a final atrial event and a final ventricular event of the given R-R interval if the first duration exceeds a consideration value and setting the current PR interval to a second duration if the first duration is equal to or less than the consideration value, wherein the second duration is equal to the first duration plus a PP interval defined as the interval between a penultimate atrial event in the given R-R interval and the final atrial event;

comparing the current PR interval to the target PR value;

determining if the current PR interval is dissociated based upon the comparison; and

delivering therapy to a patient based upon the determination of dissociation.

2. The method of claim 1, further comprising updating the target PR value with the current PR value for an R-R interval subsequent to the given R-R interval.

3. The method of claim 1, wherein the target PR value is a median of PR intervals from a predetermined number of RR intervals.

4. The method of claim 1, wherein the consideration value is approximately equal to 60 ms.

5. The method of claim 1, wherein comparing includes obtaining an absolute value of a difference between the target PR value and the current PR interval and determining further includes indicating dissociation if the absolute value of the difference exceeds a first predetermined value.

6. The method of claim 5, wherein the first predetermined values is approximately 40 ms.

7. The method of claim 1, further comprising:

determining if there were no atrial events, a single atrial event, or multiple atrial events within the given R-R interval;

classifying the given R-R interval as dissociated if there were no atrial events within the given R-R interval; and

setting the current PR interval equal to the duration between the single atrial event and the end of the given R-R interval.

8. The method of claim 1, further comprising:

detecting a greater than 1;

1 tachyarrhythmia; and

utilizing the determination of dissociation in discriminating between atrial and ventricular arrhythmia.

9. The method of claim 8, wherein discriminating between atrial and ventricular arrhythmias includes identifying whether or not a double tachyarrhythmia is occurring.

10. An implantable medical device (IMD) comprising:

means for sensing atrial events (P-waves) and ventricular events (R-waves);

means for generating a target PR value from a plurality of preceding R-R intervals;

means for identifying a given R-R interval;

means for setting a current PR interval for the given R-R interval to a first duration defined as the interval between a final atrial event and a final ventricular event of the given R-R interval if the first duration exceeds a consideration value and setting the current PR interval to a second duration if the first duration is equal to or less than the consideration value, wherein the second duration is equal to the first duration plus a PP interval defined as the interval between a penultimate atrial event in the given R-R interval and the final atrial event; and

means for comparing the current PR interval to the target PR value; and

means for determining if the current PR interval is dissociated based upon the comparison.

11. The IMD of claim 10, wherein the consideration value is approximately equal to 60 ms.

12. The IMD of claim 10, wherein the means for comparing further include

means for obtaining an absolute value of a difference between the target PR value and the current PR interval and indicating dissociation if the absolute value of the difference exceed a first predetermined value.

13. The IMD of claim 10, further comprising:

means for determining if there were no atrial events, a single atrial event, or multiple atrial events within the given R-R interval;

means for classifying the given R-R interval as dissociated if there were no atrial events within the given R-R interval; and

means for setting the current PR interval equal to the duration between the single atrial event and the end of the given R-R interval.

14. A non-transitory computer readable medium comprising instructions that when executed on a processor of an implantable medical device (IMD), cause the IMD to:

sense atrial events (P-waves) and ventricular events (R-waves);

generate a target PR value from a plurality of preceding R-R intervals;

identify a given R-R interval;

set a current PR interval for the given R-R interval to a first duration defined as the interval between a final atrial event and a final ventricular event of the given R-R interval if the first duration exceeds a consideration value and setting the current PR interval to a second duration if the first duration is equal to or less than the consideration value, wherein the second duration is equal to the first duration plus a PP interval defined as the interval between a penultimate atrial event in the given R-R interval and the final atrial event;

compare the current PR interval to the target PR value; and

determine if the current PR interval is dissociated based upon the comparison.

15. The computer readable medium of claim 14, wherein the instructions further cause the IMD to update the target PR value with the current PR value for an R-R interval subsequent to the given R-R interval.

16. The computer readable medium of claim 14, wherein the target PR value is a median of PR intervals from a predetermined number of RR intervals.

17. The computer readable medium of claim 14, wherein the consideration value is approximately equal to 60 ms.

18. The computer readable medium of claim 14, wherein when the instructions cause the IMD to compare, the IMD further obtains an absolute value of a difference between the target PR value and the current PR interval and indicates dissociation if the absolute value of the difference exceed a first predetermined value.

19. The computer readable medium of claim 18, wherein the first predetermined value is approximately 40 ms.

20. The computer readable medium of claim 14, wherein the instructions further cause the IMD to:

determine if there were no atrial events, a single atrial event, or multiple atrial events within the given R-R interval;

classify the given R-R interval as dissociated if there were no atrial events within the given R-R interval; and

set the current PR interval equal to the duration between the single atrial event and the end of the given R-R interval.