Noninvasive Fetal Electrocardiography Part II: Segmented-Beat Modulation Method for Signal Denoising

Angela Agostinelli; Agnese Sbrollini; Luca Burattini; Sandro Fioretti; Francesco Di Nardo; Laura Burattini

doi:10.2174/1874120701711010025

Noninvasive Fetal Electrocardiography Part II: Segmented-Beat Modulation Method for Signal Denoising

Open Biomed Eng J. 2017 Mar 31:11:25-35. doi: 10.2174/1874120701711010025. eCollection 2017.

Authors

Angela Agostinelli¹, Agnese Sbrollini¹, Luca Burattini², Sandro Fioretti¹, Francesco Di Nardo¹, Laura Burattini¹

Affiliations

¹ Department of Information Engineering, Università Politecnica delle Marche, Ancona, Italy.
² Department of Clinical Sciences, Università Politecnica delle Marche, Ancona, Italy.

Abstract

Background: Fetal well-being evaluation may be accomplished by monitoring cardiac activity through fetal electrocardiography. Direct fetal electrocardiography (acquired through scalp electrodes) is the gold standard but its invasiveness limits its clinical applicability. Instead, clinical use of indirect fetal electrocardiography (acquired through abdominal electrodes) is limited by its poor signal quality.

Objective: Aim of this study was to evaluate the suitability of the Segmented-Beat Modulation Method to denoise indirect fetal electrocardiograms in order to achieve a signal-quality at least comparable to the direct ones.

Method: Direct and indirect recordings, simultaneously acquired from 5 pregnant women during labor, were filtered with the Segmented-Beat Modulation Method and correlated in order to assess their morphological correspondence. Signal-to-noise ratio was used to quantify their quality.

Results: Amplitude was higher in direct than indirect fetal electrocardiograms (median:104 µV vs. 22 µV; P=7.66·10^-4), whereas noise was comparable (median:70 µV vs. 49 µV, P=0.45). Moreover, fetal electrocardiogram amplitude was significantly higher than affecting noise in direct recording (P=3.17·10^-2) and significantly in indirect recording (P=1.90·10^-3). Consequently, signal-to-noise ratio was initially higher for direct than indirect recordings (median:3.3 dB vs. -2.3 dB; P=3.90·10^-3), but became lower after denoising of indirect ones (median:9.6 dB; P=9.84·10^-4). Eventually, direct and indirect recordings were highly correlated (median: ρ=0.78; P<10^-208), indicating that the two electrocardiograms were morphologically equivalent.

Conclusion: Segmented-Beat Modulation Method is particularly useful for denoising of indirect fetal electrocardiogram and may contribute to the spread of this noninvasive technique in the clinical practice.

Keywords: Abdominal fetal electrocardiography; Digital electrocardiography; Direct fetal electrocardiography; Fetal monitoring; Nonlinear filtering; Segmented-beat modulation method.