Highly specific technique for discriminating atrial fibrillation from atrial flutter

• US 6,496,731 B1
• Filed: 04/14/2000
• Issued: 12/17/2002
• Est. Priority Date: 04/14/2000
• Status: Expired due to Term

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Lovett, Eric G.
• Primary Examiner(s): Schaetzle, Kennedy
• Application Number:
  US09/548,981
• Time in Patent Office: 977 Days
• Field of Search: 607/3, 607/4, 607/5, 607/9, 607/14, 600/515, 600/516, 600/518, 600/519
• US Class Current: 607/14
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61M 5/142 Pressure infusion, e.g. using pumps
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate

Abstract

A cardiac rhythm management system including a highly sensitive technique for discriminating AF from AFL. An electrode disposed in or about a heart senses a cardiac signal. A controller through a sensing circuit receives the sensed cardiac signal from the electrode and processes the sensed cardiac signal to compute an average cycle length-to-cycle length variation based on serial interval relationships from the sensed cardiac signal, and then comparing the computed average cycle length-to-cycle length variation to one or more pre-determined threshold values to discriminate AF from AFL. As a result of substantial difference in cycle length-to-cycle length variation between AF and AFL (despite similar average cycle lengths), the sequence-based measure of cycle length-to-cycle length variability proves to be a highly specific and reliable discriminator of AF from AFL.

Claims

1. A system, comprising:

at least one electrode;

a signal sensing circuit coupled to the electrode to sense a cardiac signal;

a controller coupled to the sensing circuit, where the controller receives the sensed cardiac signal, and where the controller includes;

an analyzer, to compute cycle lengths (Δ

t₁, Δ

t₂ . . . Δ

t_N), and an average cycle length-to-cycle length variation from the sensed cardiac signal for a pre-determined interval sequence; and

a comparator coupled to the analyzer, to compare the average cycle length-to-cycle length variation with one or more pre-determined threshold values, and to issue a command signal based on the outcome of the comparison; and

a therapy circuit coupled to the comparator, to deliver electrical energy through the at least one electrode upon receiving the command signal from the comparator.

2. The system of claim 1, where the comparator further classifies the average cycle length-to-cycle length variation to identify a cardiac arrhythmia.

3. The system of claim 2, where the comparator further classifies the average cycle length-to-cycle length variation to identify an atrial fibrillation from an atrial flutter.

4. The system of claim 2, where the comparator further classifies the average cycle length-to-cycle length variation to identify a ventricular fibrillation from a ventricular tachycardia.

5. The system of claim 1, in which the controller further includes a timer, where the timer is coupled to the comparator and provides a pre-determined variable delay for the electrical energy delivered through the at least one electrode.

6. The system of claim 5, in which the electrical energy is a pacing pulse electrical energy.

7. The system of claim 5, in which the electrical energy is a defibrillation pulse electrical energy.

8. The system of claim 1, further includes an implanted rhythm management device.

9. The system of claim 8, in which the implanted rhythm management device further includes:

a reservoir to hold a drug;

a pump coupled to the reservoir; and

a catheter, having a first end and a second end, where the first end is coupled to the pump, and the second end disposed inside a patient'"'"'s body, wherein the device administers the drug to the patient through the catheter upon receiving the command signal.

10. The system of claim 9, in which the controller further includes a timer, where the timer is coupled to the comparator and provides a pre-determined delay for administering the drug upon receiving the command signal from the comparator.

11. The system of claim 10, in which the pre-determined delay is approximately in the range of 1 second to 180 seconds.

12. The system of claim 1, wherein the cardiac signal sensed by the sensing circuit is an atrial signal.

13. The system of claim 1, wherein the cardiac signal sensed by the sensing circuit is a ventricular signal.

14. The system of claim 1, wherein the pre-determined interval sequence includes N cycle lengths.

15. The system of claim 14, wherein the N cycle lengths is approximately in a range of about 10 to 15 cycle lengths.

16. The system of claim 1, wherein the system comprises a cardiac rhythm management system.

17. A controller to discriminate an atrial fibrillation from an atrial flutter from a sensed cardiac signal, comprising:

an analyzer to compute cycle lengths, and an average cycle length-to-cycle length variation from the sensed cardiac signal for a pre-determined interval sequence; and

a comparator coupled to the analyzer, to compare the average cycle length-to-cycle length variation with a threshold value, for discriminating the atrial fibrillation from the atrial flutter from the sensed cardiac signal, and issues a command signal based on the outcome of the comparison.

18. The controller of claim 17, wherein the comparator issues the command signal to a therapy circuit to deliver electrical energy to a heart.

19. The controller of claim 18, further comprising a timer to introduce a time delay between an issuance of the command signal and a delivery of the electrical energy to the heart.

20. A system, comprising:

at least one electrode;

a signal sensing circuit coupled to the electrode to sense a cardiac signal;

a controller coupled to the sensing circuit, where the controller receives the sensed cardiac signal, and where the controller includes;

an analyzer, to compute cycle lengths (Δ

t₁, Δ

t₂ . . . Δ

t_N), and an average cycle length-to-cycle length variation from the sensed cardiac signal for a pre-determined interval sequence; and

a comparator coupled to the analyzer, to compare the average cycle length-to-cycle length variation with one or more pre-determined threshold values, and to issue a command signal based on the outcome of the comparison; and

an implanted rhythm management device.

21. The system of claim 20, in which the implanted rhythm management device further includes:

a reservoir to hold a drug;

a pump coupled to the reservoir; and

a catheter, having a first end and a second end, where the first end is coupled to the pump, and the second end disposed inside a patient'"'"'s body, wherein the device administers the drug to the patient through the catheter upon receiving the command signal.

22. The system of claim 21, in which the controller further includes a timer, where the timer is coupled to the comparator and provides a pre-determined delay for administering the drug upon receiving the command signal from the comparator.

23. The system of claim 22, in which the pre-determined delay is approximately in the range of 1 second to 180 seconds.