Devices and methods for real-time denoising of electrocardiograms
Apparatuses and methods (including methods of using such apparatuses) for de-noising electrocardiograms (ECGs) by manually or automatically adjusting the amount of filtering of an ECG signal. For example, real-time ECG signals may be filtered by combining in a weighted fashion an unfiltered portion of an ECG (or a filtered portion of the same ECG) with the same portion of the ECG that has been filtered. The weighting may be adjusted manually and/or automatically. Also described herein are methods for real-time filtering of ECG signals using a combination of filtering techniques including filtering to correct baseline wander, Savitzky-Golay denoising, and threshold smoothing. Multiple filtering techniques may be combined in a weighed manner to provide signal de-noising.
1. An ECG sensing computing device, comprising:
a processor;
one or more electrodes configured to measure an ECG signal; and
a non-transitory computer readable storage medium encoded with a computer program including instructions executable by the processor to cause the processor to:
receive the ECG signal;
filter the ECG signal by applying a first filtering stage;
apply a second filtering stage; and
apply a third filtering stage to the ECG signal, wherein the third filtering stage comprises removing low-amplitude, high frequency noise; and wherein the first, second, and third filtering stages are different from one another.
2. The device of claim 1 , wherein the computer program includes instructions that cause the processor to display the filtered ECG signal in real-time as the ECG signal is received and filtered, and wherein the displayed filtered ECG signal has improved readability such that a medical professional can better diagnose the filtered ECG signal.
3. The device of claim 1 , wherein the computer program includes instructions that cause the processor to perform the first, second, and third filtering stages in sequence.
4. The device of claim 1 , wherein the computer program includes instructions that cause the processor to perform the first, second, and third filtering stages are in parallel.
5. The device of claim 1 , wherein the first filtering stage comprises removing baseline wander of the ECG signal.
6. The device of claim 5 , wherein removing the baseline wander comprises removing a moving average of the ECG signal from a portion of the ECG signal.
7. The device of claim 1 , wherein the second filtering stage comprises removing high-frequency noise from the ECG signal.
8. The device of claim 7 , wherein removing the high-frequency noise comprises applying a Savitzky-Golay de-noising filter to smooth the ECG signal.
9. The device of claim 8 wherein applying the Savitzky-Golay de-noising filter comprises applying a high order Savitzky-Golay filter to a QRS segment of the ECG signal and applying a low order Savitzky-Golay filter to a non-QRS segment of the ECG signal.
10. The device of claim 1 , wherein the third filtering stage comprises removing low-amplitude, high frequency noise from the ECG signal.
11. The device of claim 10 , wherein removing the low-amplitude, high frequency noise from the ECG signal comprises applying threshold fit smoothing to the ECG signal.
12. The device of claim 1 , wherein the computer program includes instructions that cause the processor to pre-process the received ECG signal before filtering the ECG signal.
13. The device of claim 12 , wherein pre-processing the received ECG signal comprises applying user-selected mains filter.
14. The device of claim 1 , wherein the computer program includes instructions that cause the processor to detect an amount of noise of the received ECG signal.
15. The device of claim 14 , wherein the computer program includes instructions that cause the processor to vary an amount of filtering applied to the received ECG signal in response to the amount of noise detected.
16. The device of claim 15 , wherein detecting the amount of noise comprises training a module of a computing device with a noise model.
17. The device of claim 1 , wherein the computer program includes instructions that cause the processor to vary an amount of filtering applied to the received ECG signal in response to user input.
18. A computing device for processing an electrocardiogram (ECG) signal of a user to provide improved readability of the ECG signal for a medical professional in diagnosing the ECG signal, the device comprising:
a processor;
one or more electrodes configured to measure an ECG signal; and
a non-transitory computer readable storage medium encoded with a computer program including instructions executable by the processor to cause the processor to:
receive the measured ECG signal;
filter the received ECG signal;
display the filtered ECG signal on a display of the computing device; and
vary an amount of filtering applied to the displayed ECG signal in response to user input, wherein the amount of filtering is varied in real-time as the ECG signal is displayed, and wherein the displayed filtered ECG signal has improved readability such that a medical professional can better diagnose the filtered ECG signals.
19. The device of claim 18 , wherein the ECG signal is displayed in real-time as the ECG signal is provided and filtered.
20. The device of claim 18 , wherein to filter the received ECG signal comprises applying a first filtering stage, a second filtering stage, and a third filtering stage to the provided ECG signal, wherein the first, second, and third filtering stage are different from one another.
21. The device of claim 18 , wherein the computing device comprises one or more of a smartphone, a tablet computer, a laptop computer, a personal computer, a personal digital assistant, or a wearable computer.
22. A computing device for processing an electrocardiogram (ECG) signal of a user, the device comprising:
a processor;
one or more electrodes configured to measure an ECG signal; and
a non-transitory computer readable storage medium encoded with a computer program including instructions executable by the processor to cause the processor to:
receive the measured ECG signal;
pre-process the received ECG signal; and
filter the pre-processed ECG signal by (i) removing baseline wander of the ECG signal, (ii) removing high frequency noise from the ECG signal, and (iii) removing low- amplitude, high frequency noise from the ECG signal, wherein steps (i) to (iii) are performed sequentially.