Multiple templates for filtering of far field R-waves

• US 20030050563A1
• Filed: 09/13/2001
• Published: 03/13/2003
• Est. Priority Date: 09/13/2001
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Suribhotla, Rajasekhar V., Peterson, David K. L., Borgerding, Girard B.
• Granted Patent: US 6,810,283 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/6858 with a distal basket, e.g. expandable basket
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371

Abstract

The invention presents techniques for processing an atrial electrogram. An atrial electrogram senses atrial events, but may also sense a ventricular event, causing a far field R-wave to be present in the atrial electrogram signal. A far field R-wave is an undesired artifact. The invention provides techniques for estimating the far field R-wave and subtracting the far field R-wave from the atrial electrogram signal.

Claims

1. A method comprising:

receiving an atrial electrogram signal as a function of electrical activity of a heart;

selecting an estimated far field R-wave for a cardiac cycle from a plurality of estimated far field R-waves; and

subtracting the selected estimated far field R-wave from the atrial electrogram signal for the cardiac cycle.

2. The method of claim 1, further comprising generating a filtered atrial electrogram signal as a function of the difference between the atrial electrogram signal and the selected estimated far field R-wave.

3. The method of claim 1, further comprising:

sensing a premature ventricular contraction; and

selecting an estimated far field R-wave associated with a premature ventricular contraction.

4. The method of claim 1, further comprising:

sensing a ventricular pace; and

selecting an estimated far field R-wave associated with a ventricular pace.

5. The method of claim 1, further comprising commencing a timing window upon sensing an R-wave.

6. The method of claim 5, wherein the duration of the timing window is approximately 200 ms.

7. The method of claim 1, further comprising capturing the atrial electrogram signal.

8. The method of claim 1, further comprising converting the atrial electrogram signal to a digital atrial electrogram signal.

9. The method of claim 1, further comprising comparing the difference between the atrial electrogram signal and the selected estimated far field R-wave to a sense threshold.

10. The method of claim 1, further comprising delaying the atrial electrogram signal prior to the subtraction.

11. A device comprising:

an atrial lead; and

a filter that selects an estimated far field R-wave from a plurality of estimated far field R-waves and subtracts the selected estimated far field R-wave from an atrial electrogram signal received from the atrial lead.

12. The device of claim 11, wherein the difference between the atrial electrogram signal and the selected far field R-wave comprises a filtered atrial electrogram signal, the device further comprising a comparator that compares the filtered atrial electrogram signal to a pre-selected atrial sense threshold and generates an atrial sense signal when the filtered atrial electrogram signal exceeds the atrial sense threshold.

13. The device of claim 11, wherein the filter receives the difference between the atrial electrogram signal and the selected estimated far field R-wave and wherein the filter generates a second estimated far field R-wave as a function of the difference.

14. The device of claim 11, further comprising memory that stores a plurality of estimated far field R-waves.

15. The device of claim 11, further comprising:

a ventricular lead; and

a comparator that compares a ventricular signal received from the ventricular lead to a pre-selected ventricular sense threshold and generates a ventricular sense signal when the ventricular signal exceeds the ventricular sense threshold; and

16. A method comprising:

generating an atrial electrogram signal as a function of electrical activity of a heart;

selecting a first estimated far field R-wave for a first cardiac cycle;

subtracting the first selected estimated far field R-wave from the atrial electrogram signal for the first cardiac cycle to generate a first filtered atrial electrogram signal;

selecting a second estimated far field R-wave for a second cardiac cycle; and

subtracting the second selected estimated far field R-wave from the atrial electrogram signal for the second cardiac cycle to generate a second filtered atrial electrogram signal.

17. The method of claim 16, further comprising:

selecting the second estimated far field R-wave for a third cardiac cycle; and

adjusting the second selected estimated far field R-wave as a function of the second filtered atrial electrogram signal.

18. The method of claim 17, further comprising subtracting the adjusted second selected estimated far field R-wave from the atrial electrogram signal for the third cardiac cycle.

19. The method of claim 16, further comprising:

comparing the first filtered atrial electrogram signal to an atrial sense threshold; and

generating a P-wave sensing signal when the first filtered atrial electrogram signal exceeds the atrial sense threshold.

20. The method of claim 19, further comprising:

comparing the second filtered atrial electrogram signal to the atrial sense threshold; and

generating a P-wave sensing signal when the second filtered atrial electrogram signal exceeds the atrial sense threshold.

21. The method of claim 16, further comprising:

selecting the first estimated far field R-wave as a function of a first cardiac event; and

selecting the second estimated far field R-wave as a function of a second cardiac event.