Pilot study: Diagnosis of congenital heart disease with fetal ECG

Rationale: Congenital heart disease (CHD) is a severe condition, which needs early detection and treatment. The current method for detecting CHD during pregnancy is a structural ultrasound around week 20 of gestational age. Only 25 to 60 per cent of the cases are detected by this method. Therefore, there is need for a technique with a higher sensitivity, in order to guarantee early detection. This new technique could be the transabdominal non-invasive fetal electrocardiogram (fECG). In order to detect the different abnormalities, the normal ranges of amplitudes and segment intervals of the fECG have to be established.



Objective: To detect the normal range of amplitudes, segment intervals and the heart axis of the fECG. To compare fECG of healthy fetuses and fetuses with severe CHD.



Study design: This study will be performed as a cross-sectional and a case-cohort study. The first part of the research (cross-sectional study) will be performed in Máxima Medical Center Veldhoven (MMC) and Diagnostic Center Eindhoven (DVU). This study focuses on the normal range of (relative) amplitudes and segment intervals of the fECG. The second part (case-cohort study) will focus on the values of the amplitudes and segment intervals of fetuses diagnosed with a severe CHD like Fallot’s tetralogy. CHD is diagnosed by the current method for prenatal screening, the structural ultrasound. The center, at which the CHD is diagnosed, informs the patient about our study and contacts us if the patient is willing to participate in the study. Centers involved in this research are the tertiary care hospitals: Máxima Medical Center Veldhoven (MMC), Radboud Medical Center Nijmegen (UMCN), Acadamic Medical Center Amsterdam (AMC) and Maastricht University Medical Center (MUMC).



Study population: In the cross-sectional study, 300 pregnant patients, aged older than 18 years, with a gestational age of 18 – 24 weeks will be included to obtain 200 measurements with good fECG signal quality. The fetuses have to be healthy, without any known congenital heart abnormalities. For the case-cohort study, the fetus must be diagnosed with a severe, hemodynamic important CHD. We will include 10 patients per severe CHD with a good signal quality. The types of CHD we will include are: Fallot’s Tetralogy, hypoplastic left heart syndrome, aortic stenosis, pulmonary atresia, transposition of the great vessels, coartcation of the aorta and an atrial ventricular septal defect.



Intervention: The fECG is a non-invasive, transabdominal approach with self-adhesive electrodes. During the fECG measurement an ultrasound is made four times for a few minutes to determine the position of the fetus. The recordings are performed between 08.00 h and 16.00 h during appointments at the outpatient clinic and will take no longer than 45 minutes. The patient will be lying on a comfortable bed in a semi-recumbent position.



Main study parameters/endpoints: To determine the normal values and ranges of amplitudes, segment intervals and heart axis of healthy fetuses with a gestational age of 18 to 24 weeks. To determine the differences in fECG between healthy fetuses and fetuses diagnosed with severe CHD.

We hypothesize that the non-invasive fECG combined with the SEO has a higher detection rate for diagnosing CHD compared to the SEO alone. We expect that the fECG can detect additional details about the development and etiology of CHD.

Transabdomonal non-invasive fetal electrocardiogram