Doppler signal analysis of the tricuspid valve in healthy fetuses during the first trimester: a cohort study

Abstract Objective: This study aimed to characterize tricuspid valve sound signals in healthy fetuses during the first trimester of pregnancy using Doppler ultrasound and computational analysis. Methods: A cohort of pregnant women at 11–14 weeks of normal-risk gestation was assessed at the Instituto de Medicina Integral Prof. Fernando Figueira (IMIP) between December 2019 and May 2020. Eligible participants were over 18 years old with no pregnancy complications. Doppler recordings of the fetal tricuspid valve were obtained, and linear (wave duration) and non-linear analyses were performed, including approximate entropy (ApEn), Lempel-Ziv complexity (LZC), and detrended fluctuation analysis (DFA). Follow-up in the second trimester with a fetal medicine team and postnatal follow-up with physical examination by an experienced neonatology team confirmed normal cardiac results. Results: Early diastolic (E) wave presented a mean duration of 70.89±9.26 ms, with ApEn 0.25±0.15, LZC 0.77±0.15, and DFA 0.73. Atrial contraction (A) wave had 79.77±7.56 ms, ApEn 0.25±0.15, LZC 0.77±0.19, and DFA 0.52. Systole showed 225.95±15.88 ms, ApEn 0.15±0.17, LZC 0.78±0.15, and DFA 0.75. Diastole had 150.66±13.99 ms, ApEn 0.18±0.11, LZC 0.83±0.22, and DFA 0.66. The full cardiac cycle lasted 376.61±16.40 ms, with ApEn 0.18±0.11, LZC 0.83±0.22, and DFA 0.81. The diastole/cardiac cycle ratio was 0.4±0.3, with ApEn 0.22±0.12, LZC 0.72±0.15, and DFA 0.62. Conclusion: This study offers a detailed characterization of tricuspid valve wave segments in healthy fetuses during early gestation. The integration of linear and non-linear analyses may enhance our understanding of fetal cardiac physiology. Further research is needed to evaluate whether these parameters can assist in the early detection of congenital heart diseases. We highlight the potential of these parameters for early screening of congenital heart disease and chromosomal abnormalities, while emphasizing the need for further studies to confirm their diagnostic value.