Channel-Specific Tortuosity of Maternal Thoracic and Abdominal ECG Signals in Preeclampsia: A Pilot Feasibility Study

Abstract. Preeclampsia (P) is a major contributor to maternal–fetal morbidity, and innocuous ECG-based biomarkers could improve early detection. Tortuosity has proven useful for identifying arrhythmias but has never been tested in P. Our objective was to determine whether tortuosity can differentiate P from normoten-sive controls (C) and reveal channel-specific alterations across thoracic and ab-dominal leads. Thoracic and six abdominal ECG leads were examined in 36 preg-nant women (P = 20; C = 16). Tortuosity was quantified in overlapping 1- and 5-min windows for every lead. Maternal short-term heart-rate-variability (HRV) indices (HR, mRR, SDNN, RMSSD, pNN50) provided physiological validation. Analyses compared tortuosity between groups (P vs. C) and intra-channel differ-ences within each participant. Median tortuosity tended to be lower in P than in C, but no global between-group separation emerged. One 1-min window from abdominal channel 4 showed a group difference, and this lead consistently pro-duced the smallest p-values across analyses. HRV indices confirmed maternal autonomic impairment in P (higher HR; lower mRR, RMSSD, pNN50). Intra-channel comparisons demonstrated more disparities among leads in P than in C, with the thoracic lead diverging from every abdominal lead in both cohorts. Un-der current preprocessing and window lengths, tortuosity alone does not clearly distinguish pregnancies with P from C. Nevertheless, its reproducible, channel-specific patterns suggest latent diagnostic information. Future work should refine maternal–fetal signal separation and integrate tortuosity with established HRV indices to clarify its role within a non-invasive screening panel for preeclampsia.