Wearable Technology: Signal Recovery of Electrocardiogram from Short Spaced Leads in the Far-field Using Discrete Wavelet Transform Based Techniques
Niamh McCallan, Dewar Finlay, Pardis Biglarbeigi, Gilberto Perpiñán, Michael Jennings, Kok Yew Ng, James A. McLaughlin, Omar J. Escalona · Computing in cardiology · 2019
Bipolar ECG leads recorded from closely spaced electrodes are challenging in any context.When they are positioned distally with respect to the source field (far-field), the recovery of clinically useful signal content represents an even greater challenge.Due to the increased interest in ambulatory wellness devices, particularly wrist-worn devices, there is a renewed interest in recovering ECG signals from distally located bipolar leads.In this study 10 bipolar leads were simultaneously recorded at various locations along the left arm.At the same time, a conventional proximal reading on the chest using Lead I was also recorded and stored.This process was repeated for 11 healthy subjects.ECGs were recorded for a period of approximately 6 minutes for each subject and sampled at a frequency of 2048 Hz.Wavelet-based filtering using Daubechies 4 wavelet decomposition and soft threshold was applied to each lead.QRS detection performance was assessed against Lead I for each subject.This investigation found that a lead positioned transversally (using BIS gelled electrodes) on the upper arm provided the best accuracy against the benchmark QRS detection (SEN = 0.998, PPV = 0.984).The most distally positioned bipolar lead using dry electrodes faired least favourable (SEN = 0.272, PPV = 0.202).