Surfao-cardio study: Trans-abdominal fetal ECG analysis in the second trimester of pregnancy in a cohort of healthy fetuses

Introduction

Although feasible with ultrasound, analysis of the fetal heart rhythm sometimes remains a challenge in the absence of access to the fetal electrocardiogram. In particular in case of suspected long QT, ultrasound does not allow the measurement of the ST segment.

Objective

Within the framework of the ANR SurFAO project, the Surfao-Cardio clinical study consisted in including 20 patients whose fetus did not present any cardiac morphological abnormality, between 22SA and 29SA. A trans-abdominal electrical recording was performed. The abdominal signals were formatted and processed to extract a fetal ECG. From the latter, measurements were made, automatically for RR intervals and manually for PR intervals.

These data were compared for each patient with ultrasound measurements in different modalities (M mode, Mitral-Aorta Profile, VCS-Aorta Doppler, Pulmonary Vein-Pulmonary Artery Doppler).

Results/Expected results

The fetal heart rate was analyzable in 12 of the 20 patients with a possible analysis of the QRS morphology for 12/12 patients and of the PR for 8/12 patients.

The correlations between the ultrasound data and the fetal ECG were respectively R = 0.79 (n = 12, P < 0.05) for heart rate and R = 0.81 (n = 8, P < 0.05) for PR intervals (Figure 1).

Conclusion/Perspectives

This preliminary study showed the feasibility of trans abdominal fetal ECG with good reliability of PR measurement. Some material limitations related to the recording of the trans-abdominal ECG were identified, giving hope for an improvement in the percentage of possible measurements and access to ST-segment measurement.