Apparatus and method for ECG motion artifact removal

• US 9,931,081 B2
• Filed: 03/17/2014
• Issued: 04/03/2018
• Est. Priority Date: 03/29/2013
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Wang, Jin, Zhao, Dan, Shi, Cheng, Li, Wei
• Primary Examiner(s): Carey, Michael
• Assistant Examiner(s): Patel, Natasha
• Application Number:
  US14/780,825
• Publication Number:
  US 20160058386A1
• Time in Patent Office: 1,478 Days
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: A61B 5/7214 using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence

Abstract

The invention proposes an apparatus for reducing motion artifact in an ECG signal of a patient. The apparatus comprises a calculating unit configured to calculate a mean value beat from the ECG signal; a first obtaining unit configured to obtain a residual signal based on the ECG signal and the mean value beat calculated from the ECG signal; a filtering unit configured to perform filtering of the residual signal with one or more cut off frequencies; a second obtaining unit configured to obtain a modified ECG signal based on the filtered residual signal and the mean value beat; and a determining unit configured to determine the one or more cut off frequencies of the filtering based on an acceleration signal representative of motion status of the patient. By using the proposed apparatus, motion artifacts can be greatly removed from the ECG signal and the quality of the ECG signal can be therefore improved.

Claims

1. An apparatus for reducing motion artifact in an ECG signal obtained from a patient, the apparatus comprising:

a calculating unit configured to receive the ECG signal and to calculate a mean value beat from the ECG signal;

a first obtaining unit configured to obtain a residual signal based on the ECG signal and the mean value beat calculated from the ECG signal;

a filtering unit configured to perform filtering of the residual signal with one or more cut off frequencies;

a second obtaining unit configured to obtain a modified ECG signal using the filtered residual signal and the mean value beat; and

a determining unit configured to determine the one or more cut off frequencies of the filtering unit for filtering the residual signal using an acceleration signal representative of motion status of the patient.

2. The apparatus of claim 1, wherein the one or more cut off frequencies of the filtering comprise a signal frequency of the acceleration signal.

3. The apparatus of claim 2, wherein the signal frequency of the acceleration signal is determined according to a time interval between two successive peak values of the acceleration signal.

4. The apparatus of claim 1, wherein the one or more cut off frequencies of the filtering comprise N frequencies corresponding to top N power energy of a power spectrum of the acceleration signal.

5. The apparatus of claim 4, wherein N is in range of [1, 10].

6. The apparatus of claim 5, wherein N is 3.

7. The apparatus of claim 1, further comprising:

an adaptive filter configured to perform an adaptive filtering of the ECG signal using the acceleration signal as a reference signal,

wherein the calculating unit is configured to receive the adaptive filtered ECG signal as the ECG signal and to calculate the mean value beat from the adaptive filtered ECG signal, and

wherein the first obtaining unit is configured to obtain the residual signal based on the adaptive filtered ECG signal as the ECG signal and the mean value beat calculated from the adaptive filtered ECG signal.

8. The apparatus of claim 1, wherein the first obtaining unit comprises:

a subtracting unit configured to subtract the mean value beat from the ECG signal to obtain the residual signal.

9. The apparatus of claim 1, wherein the second obtaining unit comprises:

an adding unit configured to add the filtered residual signal back to the mean value beat to obtain the modified ECG signal.

10. A method of reducing motion artifact in an ECG signal obtained from a patient, the method comprising:

receiving the ECG signal obtained from an ECG signal sensor;

calculating a mean value beat from the ECG signal using a processor;

obtaining a residual signal based on the ECG signal and the mean value beat calculated from the ECG signal;

receiving an acceleration signal representative of motion status of the patient obtained from an acceleration sensor;

determining, using the processor, one or more cut off frequencies of a filtering unit using the acceleration signal;

filtering the residual signal using the filtering unit with one or more cut off frequencies; and

obtaining, using the processor, a modified ECG signal using the filtered residual signal and the mean value beat.

11. The method of claim 10, wherein determining the one or more cut off frequencies comprises:

determining a signal frequency of the acceleration signal using the signal frequency as the cut off frequency of the filtering.

12. The method of claim 11, wherein

the signal frequency of the acceleration signal is determined according to a time interval between two successive peak values of the acceleration signal.

13. The method of claim 10, wherein determining the one or more cut off frequencies comprises:

determining N frequencies corresponding to top N power energy of a power spectrum of the acceleration signal as the cut off frequencies of the filtering.

14. The method of claim 10, further comprising:

adaptive filtering of the ECG signal with the acceleration signal as a reference signal, prior to calculating the mean value beat,

wherein the mean value beat is calculated from the adaptive filtered ECG signal, and

wherein the residual signal is obtained based on the adaptive filtered ECG signal and the mean value beat calculated from the adaptive filtered ECG signal.