System and method for classifying sensed atrial events in a cardiac pacing system

• US 6,556,859 B1
• Filed: 04/24/2000
• Issued: 04/29/2003
• Est. Priority Date: 04/24/2000
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Munneke, Dave, Stoop, Gustaaf, Wohlgemuth, Peter W., Westendorp, Henk, Rouw, Mattias
• Primary Examiner(s): Evanisko, George R.
• Assistant Examiner(s): Oropeza, Frances P.
• Application Number:
  US09/556,663
• Time in Patent Office: 1,100 Days
• Field of Search: 600/374, 600/509, 600/513, 600/515, 600/516, 600/517, 600/518, 600/519, 600/521, 607/4, 607/5, 607/9, 607/16, 607/119
• US Class Current: 600/509
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/3704 Circuits specially adapted therefor, e.g. for sensitivity control
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion

Abstract

A system for a method of classifying distinct signals sensed from an electrode of an implantable cardiac pacing system positioned within an atrium of a heart of a patient is disclosed. The cardiac pacing system includes a pulse generator for generating pacing pulses and a controller for controlling the operation of a pacemaker. The method includes collecting atrial event signals consisting of P-wave signals and far field R-wave signals. An interim form factor histogram is generated based upon a form of collected atrial event signals. The interim form factor histogram includes an interim P-wave form factor histogram and an interim far field R-wave form factor histogram, each having bins of atrial event signals. A previously generated form factor histogram is weighted and combined with the interim form factor histogram to create a representative form factor histogram. The representative form factor histogram is analyzed to determine if a minimal safety margin is located between the representative P-wave form factor histogram and the representative far field R-wave form factor histogram. Atrial event signals are classified by form as either P-wave signals or far field R-wave signals based upon the representative form factor histogram.

Claims

1. A method of classifying signals sensed by an electrode of a medical electrical lead adapted to be positioned within an atrium of a heart of a patient, the lead forming a portion of a cardiac pacing system further comprising an implantable pulse generator for generating pacing pulses, the method comprising:

collecting atrial event signals consisting of P-wave signals and far field R-wave signals;

rejecting atrial event signals if the pulse generator is not operating under normal conditions;

generating an interim form factor histogram based upon a form of collected atrial event signals which, the interim form factor histogram including an interim P-wave form factor histogram and an interim far field R-wave form factor histogram, each having bins of atrial event signals;

discarding bins of atrial event signals within the interim form factor histogram which do not meet a discard level;

weighting a previously generated form factor histogram including a previously generated P-wave form factor histogram and a previously generated far field R-wave form factor histogram;

combining the weighted previously generated form factor histogram with the interim form factor histogram to create a representative form factor histogram;

determining if a minimal safety margin is located between a representative P-wave form factor histogram and a representative far field R-wave form factor histogram within the representative form factor histogram; and

classifying atrial event signals as either P-wave signals or far field R-wave signals based upon the representative form factor histogram.

2. The method of claim 1, wherein collecting atrial event signals further comprises:

collecting atrial event signals consisting of P-wave signals and far field R-wave signals for a time interval in the range of 5-10 days.

3. The method of claim 1, wherein collecting atrial event signals further comprises:

collecting atrial event signals consisting of P-wave signals and far field R-wave signals for a time interval for approximately 30 minutes.

4. The method of claim 1, wherein rejecting atrial event signals further comprises:

rejecting atrial event signals if a tachycardia condition is sensed by the pulse generator.

5. The method of claim 1, wherein rejecting atrial event signals further comprises:

rejecting atrial event signals if interference is present within the pulse generator.

6. The method of claim 1, wherein rejecting atrial event signals further comprises:

rejecting atrial event signals if the pulse generator is operating in an AV asynchronous state.

7. The method of claim 1, wherein discarding bins of atrial event signals further comprises:

discarding bins of atrial events signals within the interim form factor histogram which do not meet a discard level such that approximately 0%-10% of the collected atrial event signals are discarded.

8. The method of claim 1, wherein weighting a previously generated form factor histogram further comprises:

multiplying a previously generated form factor histogram by a factor in the range of 0.25-0.90.

9. The method of claim 1, wherein weighting a previously generated form factor histogram further comprises:

multiplying a previously generated form factor histogram by a factor of 0.50.

10. The method of claim 1, wherein determining if a minimum safety margin is located between a representative P-wave form factor histogram and a representative far field R-wave form factor histogram further comprises:

determining if at least a single bin width is located between a representative P-wave form factor histogram and a representative far field R-wave form factor histogram.

11. The method of claim 1, further comprising:

controlling the operation of the pulse generator based upon the representative form factor histogram such that the pacemaker properly paces and senses a heart of a patient.

12. A method of classifying signals sensed by an electrode of a medical electrical lead adapted to be positioned within an atrium of a heart of a patient, the lead forming a portion of a cardiac pacing system further comprising an implantable pulse generator for generating pacing pulses, the method comprising:

generating an interim form factor histogram which includes collected data points in the form of atrial event signal consisting of P-wave signals and far field R-wave signals;

adding the interim form factor histogram to a previously generated form factor histogram, the previously generated form factor histogram including previous collected data points, to create a representative form factor histogram; and

classifying sensed signals as P-wave signals or far field R-wave signals based upon the representative form factor histogram.

13. The method of claim 12, wherein generating an interim form factor histogram further comprises:

collecting atrial event signals consisting of P-wave signals and far field R-wave signals;

rejecting atrial event signals if the pulse generator is not operating under normal conditions; and

generating an interim form factor histogram based upon a form of collected atrial event signals which, the interim form factor histogram including an interim P-wave form factor histogram and an interim far field R-wave form factor histogram, each having bins of atrial event signals.

14. The method of claim 13, wherein collecting atrial event signals further comprises:

collecting atrial event signals consisting of P-wave signals and far field R-wave signals for a time interval in the range of 5-10 days.

15. The method of claim 13, wherein collecting atrial event signals further comprises:

collecting atrial event signals consisting of P-wave signals and far field R-wave signals for a time interval for approximately 30 minutes.

16. The method of claim 13, wherein rejecting atrial event signals further comprises;

rejecting atrial event signals if a tachycardia condition is sensed by the pulse generator.

17. The method of claim 13, wherein rejecting atrial event signals further comprises:

rejecting atrial event signals if interference is present within the pulse generator.

18. The method of claim 13, wherein rejecting atrial event signals further comprises:

rejecting atrial event signals if the pulse generator is in an AV asynchronous state.

19. The method of claim 12, wherein adding the interim form factor histogram to a previously generated form factor histogram further comprises:

discarding bins of atrial event signals within the interim form factor histogram which do not meet a discard level;

weighting a previously generated form factor histogram including a previously generated P-wave form factor histogram and a previously generated far field R-wave form factor histogram; and

combining the weighted previously generated form factor histogram with the interim form factor histogram to create a representative form factor histogram.

20. The method of claim 19, wherein discarding bins of atrial event signals further comprises:

discarding bins of atrial events signals within the internal form factor histogram which do not meet a discard level such that approximately 0%-10% of the collected atrial event signals are discarded.

21. The method of claim 19, wherein weighting a previously generated form factor histogram further comprises:

multiplying a previously generated form factor histogram by a factor in the range of 0.25-0.90.

22. The method of claim 19, wherein weighting a previously generated form factor histogram further comprises:

multiplying a previously generated form factor histogram by a factor of 0.50.

23. The method of claim 12, wherein classifying sensed signals further comprises:

determining if a minimal safety margin is located between a representative P-wave form factor histogram and a representative far field R-wave form factor histogram within the representative form factor histogram.

24. The method of claim 12, further comprising:

controlling the pulse generator based upon the representative form factor histogram such that the pulse generator properly paces and senses the heart of the patient.

25. A cardiac pacing system for classifying signals sensed from within an atrium of a heart of a patient, the cardiac pacing system comprising;

a pulse generator for generating pacing pulses;

a medical electrical lead comprising an electrode, the lead being adapted to be positioned within the atrium of the heart of the patient and operably connected to the pulse generator for delivering pacing pulses to the heart;

a sense electrode adapted to be positioned within the atrium of the heart of the patient for sensing P-waves and far field R-waves; and

a controller for generating a representative form factor histogram of the sensed P-waves and far field R-waves, for classifying sensed signals as P-wave signals or far field R-wave signals based up on the representative form factor histogram, and for controlling operation of the pulse generator based upon the representative form factor histogram.

26. The cardiac pacing system of claim 25, wherein the pulse generator further comprises an analog to digital converter for converting the sensed P-waves and far field R-waves into digital signals representing P-waves and far field R-waves.

27. The cardiac pacing system of claim 25, wherein the controller further comprises a microprocessor for generating the representative form factor histogram and for classifying sensed signals.

28. A signal classification system for classifying signals sensed by an electrode of a medical electrical lead adapted to be positioned within an atrium of a heart of a patient, the lead forming a portion of a cardiac pacing system further comprising a pulse generator for generating pacing pulses, the signal classification system comprising:

collecting means for collecting atrial event signals comprising P-wave signals and far field R-wave signals;

rejecting means for rejecting atrial event signals according to predetermined criteria;

generating means for generating an interim form factor histogram based upon a form of collected atrial event signals, the interim form factor histogram including an interim P-wave form factor histogram and an interim far field R-wave form factor histogram, each having bins of atrial event signals;

discarding means for discarding bins of atrial event signals within the interim form factor histogram which do not meet a discard level;

weighting means for weighting a previously generated form factor histogram including a previously generated P-wave form factor histogram and a previously generated far field R-wave form factor histogram;

generating means for combining the weighted previously generated form factor histogram with the interim form factor histogram to create a representative form factor histogram;

determining means for determining if a minimal safety margin is located between a representative P-wave form factor histogram and a representative far field R-wave form factor histogram within the representative form factor histogram; and

classifying means for classifying atrial event signals as either P-wave signals or far field R-wave signals based upon the representative form factor histogram.

29. A cardiac pacing system for classifying signals sensed from within an atrium of a heart of a patient, the system comprising:

pulse generator means for generating pacing pulses;

stimulation electrode means adapted to be positioned within the atrium of the heart of the patient and in communication with the pulse generator for delivering pacing pulses to the heart;

sense electrode means adapted to be positioned within the atrium of the heart of the patient for sensing P-waves and far field R-waves; and

controller means for generating a representative form factor histogram of the sensed P-waves and far field R-waves, for classifying sensed signals as P-wave signals or far field R-wave signals based upon the representative form factor histogram, and for controlling operation of the pulse generator based upon a form of the representative form factor histogram.