Algorithm for discrimination of 1:1 tachycardias

• US 6,748,269 B2
• Filed: 10/17/2001
• Issued: 06/08/2004
• Est. Priority Date: 10/17/2001
• Status: Expired due to Fees

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation), Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Thompson, Julie, Jenkins, Janice, Lovett, Eric G.
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US09/982,116
• Publication Number:
  US 20030074026A1
• Time in Patent Office: 965 Days
• Field of Search: 600/515, 600/516, 600/518, 607/4, 607/5, 607/9, 607/25
• US Class Current: 607/4
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions

Abstract

An algorithm for detection of tachycardias and for discriminating between supraventricular tachycardia (SVT) and ventricular tachycardia (VT) when a 1:1 tachycardia condition is present that can be implemented in an implantable cardiac rhythm management device. Variability measures of AV and VA intervals during the tachycardia are computed and used to distinguish between SVT and VT.

Claims

1. A cardiac rhythm management device, comprising:

an atrial sensing channel for detecting atrial senses corresponding to atrial depolarizations;

a ventricular sensing channel for detecting ventricular senses corresponding to ventricular depolarizations;

a controller for detecting arrhythmias based upon the atrial and ventricular senses detected in the sensing channels, wherein the controller is programmed to;

compute an AA interval corresponding to a cycle length between consecutive atrial senses, a VV interval corresponding to a cycle length between consecutive ventricular senses, an AV interval corresponding to a cycle length between an atrial sense and a next occurring ventricular sense with no intervening atrial sense, and a VA interval corresponding to a cycle length between a ventricular sense and a next occurring atrial sense with no intervening ventricular sense;

compute variabilities for both the VA and AV intervals based upon their measured individual cycle lengths during a specified time window;

detect a supraventricular tachycardia (SVT) when;

(a) the AA interval is within a tachycardia range defined as below an SVT threshold and (b) the VV interval is within normal limits;

detect a ventricular fibrillation (VF) when the VV interval is below a VF threshold;

detect a ventricular tachycardia (VT) when;

(a) the VV interval is within a tachycardia range defined as above the VF threshold but below a VT threshold and (b) the AA interval is either within normal limits or differs from the VV interval by more than a specified dual tachycardia limit value; and

,

if a 1;

1 tachycardia condition is present, defined as when the AA and VV intervals are both within their tachycardia ranges and differ from one another by no more than a specified 1;

1 limit value, discriminate between a supraventricular tachycardia and a ventricular tachycardia based upon a relative variability of the VA and AV intervals.

2. The device of claim 1 wherein the AA, VV, VA, and AV intervals are statistics computed from individual cycle lengths measured during a data collection time window.

3. The device of claim 2 wherein the AA, VV, VA, and AV intervals are medians of individual cycle lengths measured during the data collection time window.

4. The device of claim 1 wherein the controller is further programmed to detect an atrioventricular nodal reentrant tachycardia (AVNRT) when a 1:

1 tachycardia condition is present and when either the AV or VA interval is less than a specified AVNRT limit value, irrespective of the AV and VA interval variabilities.

5. The device of claim 1 wherein the controller is further programmed to discriminate between a supraventricular tachycardia and a ventricular tachycardia when a 1:

1 tachycardia condition is present by;

detecting a supraventricular tachycardia if the VA interval variability exceeds the AV interval variability;

detecting a ventricular tachycardia if the AV interval variability exceeds the VA interval variability.

6. The device of claim 1 wherein the controller is further programmed to discriminate between a supraventricular tachycardia and a ventricular tachycardia when a 1:

1 tachycardia condition is present and the VV interval is more than a specified ratebreak threshold value, irrespective of the AV and VA interval variabilities, by;

detecting a supraventricular tachycardia if the VA interval exceeds the AV interval; and

,

detecting a ventricular tachycardia if the AV interval exceeds the VA interval.

7. The device of claim 6 wherein the controller is further programmed to discriminate between a supraventricular tachycardia and a ventricular tachycardia when a 1:

1 tachycardia condition is present based upon the relative variability of the VA and AV intervals, irrespective of whether the VV interval is more than the specified ratebreak threshold value, when a patient in whom the device is operating has an AV nodal block.

8. The device of claim 7 wherein the controller is further programmed to discriminate between a supraventricular tachycardia and a ventricular tachycardia when a 1:

1 tachycardia condition is present and the patient in whom the device is operating has an AV nodal block, irrespective of the relative variability of the VA and AV intervals, by detecting a ventricular tachycardia if a measured AV conduction time in the patient is less than a specified AV block limit value and the AV interval is greater than a specified tachycardia AV limit value.

9. The device of claim 8 wherein the specified AV block limit value is 270 milliseconds and the specified tachycardia limit value is 300 milliseconds.

10. The device of claim 1 wherein the controller is further programmed to compute each of the AV and VA interval variabilities as a measure selected from a group consisting of:

a variance of the cycle lengths measured during the specified time window, a difference between the maximum and minimum cycle lengths measured during the specified time window after the exclusion of outlier values, a difference between an upper percentile value and a lower percentile value of the cycle lengths measured during the specified time window after the exclusion of outlier values, and an average deviation that is calculated as the sum of the absolute value of the difference of each cycle length from the mean divided by the number of cycle lengths in the time window.

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

detecting atrial senses corresponding to atrial depolarizations;

detecting ventricular senses corresponding to ventricular depolarizations;

computing an AA interval corresponding to a cycle length between consecutive atrial senses, a VV interval corresponding to a cycle length between consecutive ventricular senses, an AV interval corresponding to a cycle length between an atrial sense and a next occurring ventricular sense with no intervening atrial sense, and a VA interval corresponding to a cycle length between a ventricular sense and a next occurring atrial sense with no intervening ventricular sense;

computing variabilities for both the VA and AV intervals based upon their measured individual cycle lengths during a specified time window;

detecting a supraventricular tachycardia (SVT) when;

(a) the AA interval is within a tachycardia range defined as below an SVT threshold and (b) the VV interval is within normal limits;

detecting a ventricular fibrillation (VF) when the VV interval is below a VF threshold;

detecting a ventricular tachycardia (VT) when;

(a) the VV interval is within a tachycardia range defined as above the VF threshold but below a VT threshold and (b) the AA interval is either within normal limits or differs from the VV interval by more than a specified dual tachycardia limit value; and

,

if a 1;

1 tachycardia condition is present, defined as when the AA and VV intervals are both within their tachycardia ranges and differ from one another by no more than a specified 1;

1 limit value, discriminating between a supraventricular tachycardia and a ventricular tachycardia based upon a relative variability of the VA and AV intervals.

12. The method of claim 11 wherein the AA, VV, VA, and AV intervals are statistics computed from individual cycle lengths measured during a data collection time window.

13. The method of claim 12 wherein the AA, VV, VA, and AV intervals are medians of individual cycle lengths measured during the data collection time window.

14. The method of claim 11 further comprising detecting an atrioventricular nodal reentrant tachycardia (AVNRT) when a 1:

1 tachycardia condition is present and when either the AV or VA interval is less than a specified AVNRT limit value, irrespective of the AV and VA interval variabilities.

15. The method of claim 11 further comprising discriminating between a supraventricular tachycardia and a ventricular tachycardia when a 1:

1 tachycardia condition is present by;

detecting a supraventricular tachycardia if the VA interval variability exceeds the AV interval variability;

detecting a ventricular tachycardia if the AV interval variability exceeds the VA interval variability.

16. The method of claim 11 further comprising discriminating between a supraventricular tachycardia and a ventricular tachycardia when a 1:

1 tachycardia condition is present and the VV interval is more than a specified ratebreak threshold value, irrespective of the AV and VA interval variabilities, by;

detecting a supraventricular tachycardia if the VA interval exceeds the AV interval; and

,

detecting a ventricular tachycardia if the AV interval exceeds the VA interval.

17. The method of claim 16 further comprising discriminating between a supraventricular tachycardia and a ventricular tachycardia when a 1:

1 tachycardia condition is present based upon the relative variability of the VA and AV intervals, irrespective of whether the VV interval is more than the specified ratebreak threshold value, when a patient in whom the device is operating has an AV nodal block.

18. The method of claim 17 further comprising discriminating between a supraventricular tachycardia and a ventricular tachycardia when a 1:

1 tachycardia condition is present and the patient in whom the device is operating has an AV nodal block, irrespective of the relative variability of the VA and AV intervals, by detecting a ventricular tachycardia if a measured AV conduction time in the patient is less than a specified AV block limit value and the AV interval is greater than a specified tachycardia AV limit value.

19. The method of claim 18 wherein the specified AV block limit value is 270 milliseconds and the specified tachycardia limit value is 300 milliseconds.

20. The method of claim 11 wherein the AV and VA interval variabilities are computed as variances of their individual cycle lengths measured during the specified time window.

21. The method of claim 11 wherein the AV and VA interval variabilities are each computed as a difference between the maximum and minimum cycle lengths measured during the specified time window after the exclusion of outlier values.

22. The method of claim 11 wherein the AV and VA interval variabilities are each computed as a difference between an upper percentile value and a lower percentile value of the cycle lengths measured during the specified time window after the exclusion of outlier values.

23. The method of claim 11 wherein the AV and VA interval variabilities are each computed as an average deviation that is calculated as the sum of the absolute value of the difference of each cycle length from the mean divided by the number of cycle lengths in the time window.

24. The method of claim 11 wherein the AV and VA interval variabilities are each computed as a sum of consecutive cycle length differences measured during the time window.

25. A cardiac rhythm management device configured to detect atrial and ventricular beats and further configured to discriminate between a supraventricular tachycardia and a ventricular tachycardia by comparing a variability of an AV interval, defined as the interval between an atrial beat and a next occurring ventricular beat with no intervening atrial beat, with a variability of a VA interval, defined as the interval between a ventricular b eat and a next occurring atrial beat with no intervening ventricular beat.

26. A method for discriminating between a supraventricular tachycardia and a ventricular tachycardia, comprising comparing a variability of an AV interval, defined as the interval between an atrial beat and a next occurring ventricular beat with no intervening atrial beat, with a variability of a VA interval, defined as the interval between a ventricular beat and a next occurring atrial beat with no intervening ventricular beat.