Model based estimation of QT intervals in non-invasive fetal ECG signals

• Published in: PloS one Vol. 15; no. 5; p. e0232769
• Main Authors: Widatalla, Namareq, Kasahara, Yoshiyuki, Kimura, Yoshitaka, Khandoker, Ahsan
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 11.05.2020; Public Library of Science (PLoS)
• Subjects: Anomalies; Arrhythmia; Biology and Life Sciences; Biomedical engineering; Capacitors; Cardiac function; Congenital heart defects; Death; Defects; Diagnosis; Doppler effect; EKG; Electrocardiography; Engineering; Engineering and Technology; Fetal heart rate; Fetal monitoring; Fetuses; Genetic disorders; Gestational age; Heart; Hypoxia; Infant mortality; Information technology; Interdisciplinary aspects; Intervals; Magnetocardiography; Mathematical models; Measurement; Medicine and Health Sciences; Methods; Model testing; Novels; Patient monitoring equipment; Physical Sciences; Pregnancy; Pregnant women; Research and Analysis Methods; Scalp; Sodium; Studies; Ultrasonic imaging; Ultrasound; University graduates; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0232769

The end timing of T waves in fetal electrocardiogram (fECG) is important for the evaluation of ST and QT intervals which are vital markers to assess cardiac repolarization patterns. Monitoring malignant fetal arrhythmias in utero is fundamental to care in congenital heart anomalies preventing perinatal death. Currently, reliable detection of end of T waves is possible only by using fetal scalp ECG (fsECG) and fetal magnetocardiography (fMCG). fMCG is expensive and less accessible and fsECG is an invasive technique available only during intrapartum period. Another safer and affordable alternative is the non-invasive fECG (nfECG) which can provide similar assessment provided by fsECG and fMECG but with less accuracy (not beat by beat). Detection of T waves using nfECG is challenging because of their low amplitudes and high noise. In this study, a novel model-based method that estimates the end of T waves in nfECG signals is proposed. The repolarization phase has been modeled as the discharging phase of a capacitor. To test the model, fECG signals were collected from 58 pregnant women (age: (34 ± 6) years old) bearing normal and abnormal fetuses with gestational age (GA) 20-41 weeks. QT and QTc intervals have been calculated to test the level of agreement between the model-based and reference values (fsECG and Doppler Ultrasound (DUS) signals) in normal subjects. The results of the test showed high agreement between model-based and reference values (difference < 5%), which implies that the proposed model could be an alternative method to detect the end of T waves in nfECG signals.