Related Experiment Video
Updated: Aug 25, 2026
Fetal Echocardiography and Pulsed-wave Doppler Ultrasound in a Rabbit Model of Intrauterine Growth Restriction
Published on: June 29, 2013
Evaluating the Accuracy of Non-invasive Pulsed-Wave Doppler Echocardiography in Measuring Fetal QT and PR Intervals:
Feisal Rahimpour1, Lida Jarahi2, Hasan Birjandi3
1Department of Pediatric Cardiologist, Interventional Electrophysiologist, Mashhad Cardiovascular Medical and Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Insights
Pulsed-wave Doppler echocardiography accurately measures fetal QT and PR intervals, showing good agreement with fetal magnetocardiography. This non-invasive method offers a practical alternative for prenatal screening of cardiac conditions.
Area of Science:
- Cardiology
- Fetal Medicine
- Diagnostic Imaging
Background:
- Congenital Long QT Syndrome (LQTS) poses a risk for infant arrhythmias and sudden cardiac death.
- Fetal Magnetocardiography (fMCG) provides accurate fetal cardiac interval measurements but is limited in availability.
- Assessing fetal cardiac repolarization and conduction is crucial for prenatal diagnosis.
Purpose of the Study:
- To evaluate the diagnostic accuracy of pulsed-wave (PW) Doppler echocardiography for fetal QT and PR intervals.
- To compare echocardiographic measurements with established fetal magnetocardiography (fMCG) normative data.
- To determine the feasibility of echocardiography as an accessible alternative to fMCG.
Main Methods:
- A cross-sectional study involving 576 pregnant women (16-38 weeks' gestation).
- Standardized PW Doppler echocardiography used for fetal PR and QT interval measurements.
- Comparison with fMCG normative data and contemporaneous fMCG in a subset of 42 fetuses.
Main Results:
- PW Doppler demonstrated strong agreement with fMCG for PR (ICC=0.89) and QT (ICC=0.82) intervals.
- Sensitivity and specificity for detecting prolonged intervals were 85% and 78%, respectively.
- Echocardiography showed no significant correlation with gestational age or significant differences in fetal heart rate.
Conclusions:
- PW Doppler echocardiography is a reliable method for measuring fetal QT and PR intervals.
- The technique shows good agreement with fMCG, serving as a practical substitute.
- This non-invasive approach enhances prenatal screening accessibility for cardiac abnormalities.
Introduction:
Congenital Long QT Syndrome (LQTS) is a common cause of potentially life-threatening ventricular arrhythmias and sudden cardiac death in infants and children. Fetal Magnetocardiography (fMCG) is available in only a few specialized centers worldwide and offers accurate measurements of the QT and PR intervals. The aim of this study was to assess the diagnostic accuracy of PW Doppler echocardiographic measurement of fetal QT and PR intervals compared with the available normative data for fMCG.
Methods:
576 pregnant women with singleton pregnancies (16-38 weeks' gestation) were studied in this cross-sectional study between 2022 and 2023 with detailed fetal echocardiograms. Standardized pulsed-wave Doppler techniques were used to measure the PR and QT intervals. Results were compared with published normative data for fMCG, adjusted for gestational age, and were also compared with contemporaneous fMCG in a subset of 42 fetuses.
Results:
Mean QT interval (echo) was 270.0 ± 38.8 and mean PR interval was 119.3 ± 16.2. In the paired subset (n = 42), strong agreement was observed (PR ICC = 0.89 [95% CI: 0.81-0.94]; QT ICC = 0.82 [95% CI: 0.72-0.89]), with mean biases of +2.1 ms and +6.8 ms on Bland-Altman analysis, respectively. Sensitivity and specificity for the full cohort for prolonged intervals (> 95th percentile of GA-adjusted fMCG norms) were 85% and 78% (PPV 68%, NPV 90%). There were no clinically significant differences for PR interval or fetal heart rate, and there was no significant correlation between measured intervals and gestational age (p > 0.05).
Discussion:
Pulsed-wave Doppler echocardiography is a reliable method for measuring fetal QT and PR intervals and is in good agreement with fMCG.
Conclusion:
It is a practical, non-invasive, and easily accessible substitute for fMCG when it is not available for prenatal screening of cardiac repolarization and conduction abnormalities.
