Detection of ventricular ectopic beats using ventricular electrogram

• US 6,453,192 B1
• Filed: 03/13/2000
• Issued: 09/17/2002
• Est. Priority Date: 03/13/2000
• Status: Expired due to Fees

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Spinelli, Julio C., Yu, Yinghong, Ding, Jiang
• Primary Examiner(s): Layno, Carl H.
• Application Number:
  US09/523,616
• Time in Patent Office: 918 Days
• Field of Search: 600/516, 607/25
• US Class Current: 600/516
• CPC Class Codes: A61B 5/364 Detecting abnormal ECG interval, e.g. extrasystoles, ectopic heartbeats
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions

Abstract

A method of accurately determining if ectopic beats are occurring in the heart by detecting the time interval, T, between a point Q* defined is the onset of the QRS complex and the peak value of R (T=Q*R) during a heart beat cycle and comparing that time with a running mean value calculated from normal heartbeats. A beat is identified as an ectopic beat if the Q*R time interval for a current beat is at least four standard deviations from the mean Q*R time interval of normal preceding beats. The electrodes for detecting the ectopic beats may be inside the patient'"'"'s heart or on the patient'"'"'s skin. If more than one electrode is used for monitoring the depolarization of the heart, then by combining the Q*R intervals (e.g. using a triangulation method) calculated from different electrodes, the location of the ectopic excitation can be determined and identified. The method of determining and localizing ectopic beats may be used in a pacing device to initiate ectopic beat handling procedures and to analyze the nature and possible trend of ectopic activities. This method of using the Q*R interval is independent of the PR or RR intervals normally measured and used to detect early ectopic beats and is therefore a more accurate method, since ectopic beats may occur at any time independent of PR or RR intervals.

Claims

1. Apparatus for detecting ectopic beats in a heart of a patient comprising:

(a) a sensor coupled to the patient that detects ventricular depolarization signals including successive QRS complexes;

(b) an electronic circuit responsive to an output of the sensor for determining on a beat-to-beat basis, a time interval, T, corresponding to a QR interval of the QRS complex;

(c) a threshold establishing device operative to process sampled values of the interval, T, over a predetermined plurality of heartbeat cycles to develop a threshold value; and

(d) a comparator for comparing the T value of a current beat to the threshold value and for signaling the occurrence of an ectopic beat based upon result of the comparison.

2. The apparatus of claim 1 wherein the means for developing a threshold establishing device comprises:

(a) a computer programmed to dynamically calculate an average length of said time interval, T, over said predetermined plurality of heart beat cycles and a predetermined multiple of a standard deviation of said time interval, T, over said plurality of heartbeat cycles.

3. Apparatus for detecting ectopic beats in a heart of a patient, comprising:

(a) means for sensing ventricular depolarization signals including successive QRS complexes;

(b) means responsive to the sensing means for determining, on a beat-to-beat basis, a time interval, T, between a point, Q*, on the QRS complex where an absolute slope reaches a predetermined percentage of a maximum absolute slope of the QRS complex prior to maximum peak slope of the QRS complex and the largest peak of the QRS complex, R;

(c) means for dynamically calculating an average length of said time interval, T, over a plurality of heartbeat cycles, and a standard deviation of said time interval over said plurality of heartbeat cycles; and

(d) means for comparing a Q*R interval for a current beat with a predetermined multiple of the standard deviation of said time interval over said plurality of heartbeats to identify whether the current beat is an ectopic beat.

4. The apparatus as in claim 3 wherein the means for comparing determines whether the Q*R interval for a current beat is at least four of said standard deviations.

5. The apparatus of claim 4 and further including memory means for storing a time of occurrence where the Q*R interval for a current beat is at least four of said standard deviations.

6. The apparatus as in claim 3 wherein the means for sensing comprises at least one electrode operatively coupled to the heart of the patient.

7. The apparatus as in claim 6 wherein the at least one electrode is disposed on the left ventricle of the heart.

8. The apparatus as in claim 6 wherein the at least one electrode is disposed within the right ventricle of the heart.

9. The apparatus as in claim 6 wherein the at least one electrode is disposed on the chest of a patient.

10. The apparatus of claim 3 wherein the means responsive to the sensing means comprises:

means for converting the ventricular depolarization signals to a digital data representative thereof; and

a microprocessor programmed to perform signal processing on the digital data and to compute the Q* point and an R value and a time interval between the Q* points and the R value for each of a plurality of sequential heartbeats.

11. The apparatus of claim 10 wherein the microprocessor is programmed to dynamically calculate the average length of said time interval, T, over a plurality of heartbeat cycles and the standard deviation of the time interval over said plurality of heartbeat cycles and to compare the Q*R interval for a current beat with a predetermined multiple of the standard deviation of said time interval over said plurality of heartbeats.

12. Apparatus for detecting ectopic beats in a heart of a patient comprising:

(a) an implantable cardiac rhythm management device having a microprocessor coupled in controlling relation to a stimulating pulse generator, said microprocessor adapted to receive electrogram data from at least one sensing electrode disposed in or on the heart, the microprocessor programmed to compute a time interval, T, between a first detected cardiac event in the electrogram data and a second detected cardiac event in the electrogram data on a beat-to-beat basis and a mean value and a standard deviation of T over a predetermined number of intrinsic beats, the microprocessor further programmed to compare the interval T of a current intrinsic heartbeat to a predetermined multiple of the computed standard deviation; and

(b) a memory coupled to the microprocessor adapted to store information identifying an occurrence of an ectopic beat when the interval T of the current intrinsic beat equals or exceeds the predetermined multiple of the standard deviation.

13. The apparatus of claim 12 and further including an electrical lead having an electrode for picking up said electrogram data, and a conductor connecting the electrode to the implantable cardiac rhythm management device.

14. The apparatus of claim 12 and further including an analog-to-digital converter coupled to receive the electrogram data from the sensing electrode and provide a digital representation thereof to the microprocessor.

15. Apparatus for detecting ectopic beats in the heart comprising:

a sensor for detecting electrical activity in the heart,

a lead for transmitting electrical signals from the sensor,

an amplifier connected to the lead for amplifying the electrical activity signals detected by the sensor,

an analog to digital converter connected to the amplifier to change the analog signal to a digital signal, and

a microprocessor with a memory for storing the digital signal data and programmed for calculating a Q*R interval for each beat, the mean Q*R interval and the standard deviation of the mean Q*R interval and comparing the Q*R interval of a beat to a predetermined multiple of the standard deviation to determine an ectopic beat has occurred.

16. Apparatus for detecting ectopic beats in the heart as in claim 15 and further having:

a transmitter for sending data from the microprocessor to a receiver for recording and displaying data acquired from the heart.

17. Apparatus for detecting ectopic beats in the heart as in claim 15 and further having:

a variable frequency pulse generator connected to the microprocessor for generating pulses to be sent to the heart at the microprocessor'"'"'s command,

a lead from the pulse generator to the heart for carrying the pulse to the heart, and

an electrode coupled to the heart for receiving the pulse and stimulating the heart.

18. A method for detecting ectopic beats in a heart comprising:

detecting electrical activity in the heart on a beat-to-beat basis to obtain Q−

R interval values,

computing a mean Q−

R interval and its standard deviation over a predetermined number of normal heartbeats, and

comparing the Q−

R interval of a current heartbeat to determine whether it is greater than a predetermined number of standard deviations of the mean Q−

R interval for determining if an ectopic beat has occurred.

19. A method for detecting ectopic beats in a heart as in claim 18 further comprising:

sensing electrical events in the heart from one sensor to provide the onset of the QRS complex and a peak value R for determining the QR interval of each beat.

20. A method for detecting ectopic beats in a heart as in claim 19 further comprising:

placing the sensor on the left ventricular endocardium.

21. A method for detecting ectopic beats in a heart as in claim 19 further comprising:

placing the sensor on the left ventricular epicardium.

22. A method for detecting ectopic beats in a heart as in claim 19 further comprising:

placing the sensor in the right ventricle.

23. A method for detecting ectopic beats in a heart as in claim 19 further comprising:

placing the sensor on a patient'"'"'s chest.

24. A method for detecting ectopic beats in a heart as in claim 18 further comprising:

detecting electrical activity in the heart from more than one sensor to provide data for determining an ectopic focus.

25. A method for detecting ectopic beats in a heart as in claim 24 further comprising:

storing times of occurrence of detected ectopic beats in groups to assess the frequency and place of origin of ectopic beats.

26. A method for detecting ectopic beats in a heart as in claim 18 further comprising:

transmitting QR interval data, mean QR interval data and mean standard deviation of QR interval data to a device for recording and displaying the data to a health care provider for monitoring and diagnosis of patients.

27. A method for detecting ectopic beats in a heart as in claim 18 and further including the steps of:

dynamically smoothing electric signals representative of the ECG waveform using a weighted N-point moving window; and

where R defined as the largest peak in a smoothed QRS complex; and

the onset of the QRS complex as a Q* data point is measured as the earliest point on the smoothed QRS complex where the slope of the QRS wave is a predetermined percentage of the maximum slope of the QRS complex prior to the R data point.

28. A method for detecting ectopic beats in a heart as in claim 18 wherein:

computing the mean and standard deviation of the time interval between the Q and R data point comprises the steps of solving the following equations wherein normal intrinsic beats only are used;

29. Apparatus for detecting ectopic beats in a heart of a patient comprising:

(a) an implantable cardiac rhythm management device having a microprocessor coupled in controlling relation to a stimulating pulse generator, said microprocessor adapted to receive electrogram data from at least one sensing electrode disposed in or on the heart, the microprocessor programmed to compute a time interval, T, between a first detected cardiac event in the electrogram data and a second detected cardiac event in the electrogram data on a beat-to-beat basis and a mean value and a standard deviation of T over a predetermined number of intrinsic beats, the microprocessor further programmed to compare the interval T of a current intrinsic heartbeat to a valve equal to four times the computed standard deviation; and

(b) a memory coupled to the microprocessor adapted to store information identifying an occurrence of an ectopic beat when the interval T of the current intrinsic beat equals or exceeds the predetermined multiple of the standard deviation.

30. Apparatus for detecting ectopic beats in a heart of a patient comprising:

(a) an implantable cardiac rhythm management device having a microprocessor coupled in controlling relation to a stimulating pulse generator, said microprocessor adapted to receive electrogram data from at least one sensing electrode disposed in or on the heart, the microprocessor programmed to compute a time interval, T, between a first detected cardiac event in the electrogram data and a second detected cardiac event in the electrogram data on a beat-to-beat basis and a mean value and a standard deviation of T over a predetermined number of intrinsic beats, the microprocessor further programmed to compare the interval T of a current intrinsic heartbeat to a predetermined multiple of the computed standard deviation,

(b) a memory coupled to the microprocessor adapted to store information identifying an occurrence of an ectopic beat when the interval T of the current intrinsic beat equals or exceeds the predetermined multiple of the standard deviation; and

(c) an analog-to-digital converter coupled to receive the electrogram data from the sensing electrode and to provide a digital representation thereof to the microprocessor, the microprocessor being programmed to provide dynamic smoothing to the digital representation of the electrogram data.