Multidimensional decomposition framework for electrocardiographic interference, noise and artifacts removal from...

Accurate extraction of respiratory diaphragmatic electromyography (dEMG) is hindered by electrocardiographic (ECG) interference, motion artifacts, and noise. Existing methods, although effective, may remove physiologically relevant information. To enable robust ECG and artifact suppression while maintaining respiratory-related amplitude variations, a higher-order singular value decomposition (HO-SVD) based approach was developed.

The HO-SVD algorithm exploits the multidimensional structure of dEMG recordings by jointly decomposing the temporal, overlapped QRS complexes, and spatial (channel) dimensions. The method enables targeted suppression of coherent and repetitive artifacts prior to signal reconstruction. Performance was evaluated on three synthetic datasets and on clinical data from ten patients with obstructive sleep apnea, using a previously developed two-dimensional SVD algorithm (SVD_RI) as a reference.

Across synthetic datasets, HO-SVD consistently outperformed SVD_RI in all evaluation metrics. In clean conditions, HO-SVD improved the median signal-to-noise ratio (SNR) by 27 dB (131%) relative to the original signal. In datasets with mild motion artifacts and complex muscle interference, median SNR improvements of up to 19 dB (88%) were observed. The symmetric mean absolute error and mean frequency deviation were significantly lower for HO-SVD across all input SNRs (p<0.0001) compared to SVD_RI. In clinical data, HO-SVD achieved a significantly higher correlation with reference esophageal pressure (p<0.02), greater ECG suppression (p<0.0001), and fewer outliers (p<0.0001) than SVD_RI.

These results demonstrate that incorporating a third (spatial) dimension and adaptive thresholding across tensor modes enables robust removal of ECG interference and motion artifacts while preserving respiratory dEMG modulation. The proposed HO-SVD framework offers a flexible and effective approach for multichannel biomedical signal denoising.