Ultrasonography.
2025 May;44(3):212-219. 10.14366/usg.24142.
Development of a Z-score equation for atrioventricular interval measurement by two-dimensional pulsed Doppler echocardiography in normal fetuses between 16 and 33+6 weeks of gestation
- Amorim LAdR
1 - Bravo-Valenzuela NJ2
- Almeida SLdM1
- Peixoto AB3
- Nicoloso LHS4
- Schmidt MM4
- Zielinsky P4
- Júnior EA5,6
- Affiliations
-
- 1Postgraduate Program in Health Sciences, Medical School, Federal University of Amazonas (UFAM), Manaus, AM, Brazil
- 2Department of Pediatrics, Pediatric Cardiology, School of Medicine, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil
- 3Department of Obstetrics and Gynecology, Federal University of Triângulo Mineiro (UFTM), Uberaba, MG, Brazil
- 4Fetal Cardiology Unit, Institute of Cardiology of Rio Grande do Sul, Porto Alegre, RS, Brazil
- 5Department of Obstetrics, Paulista School of Medicine, Federal University of São Paulo (EPMUNIFESP), São Paulo, SP, Brazil
- 6Discipline of Woman Health, Municipal University of São Caetano do Sul (USCS), São Caetano do Sul, SP, Brazil, Brazil
- KMID: 2567441
- DOI: http://doi.org/10.14366/usg.24142
Abstract
- Purpose
Fetal echocardiography is the primary diagnostic tool for assessing the atrioventricular (AV) time interval. Establishing a reference range for this parameter throughout pregnancy is essential for the early detection of potential abnormalities. The aim of this study was to develop a Z-score equation and establish specific percentiles for the AV time interval in normal fetuses between 16 and 33+6 weeks of gestation.
Methods
A multicenter, prospective, cross-sectional study was conducted between 2018 and 2022. A large sample of pregnant women meeting specific eligibility criteria was included, while cases with potential confounders were excluded. Two-dimensional echocardiography with pulsed Doppler techniques was employed, focusing on the left ventricular inflow and outflow. Data were rigorously analyzed with careful assessment of measurements and normalization procedures.
Results
In total, 1,309 echocardiograms were performed, and 1,183 pregnant women were included after applying the eligibility criteria. Detailed percentiles for each gestational age were determined, and a Z-score equation was formulated. A very weak correlation was observed between AV interval measurement and gestational age (r=0.16, P<0.001). In addition, the correlation between AV interval measurement and fetal heart rate was weak (r=-0.21, P<0.001). The Z-score for the AV interval measurement in milliseconds was derived as follows: Z-score=(AV interval measurement-111.3)/8.6.
Conclusion
This study provides a reference range and Z-score equation for the AV interval, which may enhance the accuracy of monitoring fetuses at risk for developing atrioventricular block—especially in pregnant women with specific antibodies—thus facilitating earlier diagnosis and treatment.
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