pecg package

pecg.Preprocessing

class pecg.Preprocessing.Preprocessing(signal: numpy.array, fs: int)[source]

Bases: object

The Preprocessing class provides some routines for pre-filtering

the ECG signal as well as estimating the signal quality.

Parameters
  • signal – the ECG signal as a ndarray, with shape (L, N) when L is the number of channels or leads and N i the number of samples.

  • fs – The sampling frequency of the signal.

import pecg

from pecg import Preprocessing as Pre

pre = Pre.Preprocessing(signal, fs)
notch(n_freq: int)[source]

The notch function applies a notch filter in order to remove the power line artefacts.

Parameters

n_freq – The expected center frequency of the power line interference. Typically, 50Hz (e.g. Europe) or 60Hz (e.g. US)

Returns

The filtered ECG signal, with shape (L, N) when L is the number of channels or leads and N is the number of samples.

f_notch = 60

filtered_ecg_rec = pre.notch(f_notch)
bpfilt()[source]

The bpfilt function applies a bandpass filter between [0.67, 100] Hz,

this function uses a zero-phase Butterworth filter with 75 coefficients.

Returns

The filtered ECG signal, with shape (L, N) when L is the number of channels or leads and N is the number of samples.

filtered_ecg_rec = pre.bpfilt()
bsqi(peaks: numpy.array = array([], dtype=float64), test_peaks: numpy.array = array([], dtype=float64))[source]

bSQI is an automated algorithm to detect poor-quality electrocardiograms.

This function is based on the following paper:1.

The implementation itself is based on: 2.

1

Li, Qiao, Roger G. Mark, and Gari D. Clifford.

“Robust heart rate estimation from multiple asynchronous noisy sources

using signal quality indices and a Kalman filter.”

Physiological measurement 29.1 (2007): 15.

2

Behar, J., Oster, J., Li, Q., & Clifford, G. D. (2013).

ECG signal quality during arrhythmia and its application to false alarm reduction.

IEEE transactions on biomedical engineering, 60(6), 1660-1666.

Parameters
  • peaks – Optional input- Annotation of the reference peak detector (Indices of the peaks), as an ndarray of shape (L,N), when L is the number of channels or leads and N is the number of peaks. If peaks are not given, the peaks are calculated with epltd detector.

  • test_peaks – Optional input - Annotation of the anther reference peak detector (Indices of the peaks), as an ndarray of shape (L,N), when N is the number of peaks. If test peaks are not given, the test peaks are calculated with xqrs detector.

Returns

The ‘bsqi’ score, a flout between 0 and 1.

epltd_peaks = fp.epltd()

xqrs_peaks = fp.xqrs()

bsqi_score = pre.bsqi(epltd_peaks, xqrs_peaks)

if bsqi_score < 0.8:

    print('It's a bad quality ECG recording!')

Module contents