Introduction: Accurate assessment of atrioventricular conduction time (AV) is crucial for early detection of envolving fetal heart block. DTI-derived AV intervals correlate better with PR intervals in ECG than do other fetal echocardiographic approaches.
Objective: To establish gestational age-specific reference values of normal fetal AV intervals by spectral DTI in healthy singleton fetuses.
Methods: AV intervals were measured from atria contraction (Am) to isovolumic contraction (IV) at the right ventricular free wall in 140 subjects with normal cardiac and extracardiac anatomy between 18 and 40 week’s gestation. All fetuses had sinus rhythm. Examinations were performed using Sequoia 512, with cardiological probe of 2.5-5 MHz and pediatric cardiology software. The sample volumes were placed in the basal part of RV in the 4-chamber view.
Results: There was a negative correlation between AV intervals and FHR (p<0,001, r=-0,318) and positive correlation with gestational age (p=0,049; r=0,167). The table shows reference values for AV intervals by gestational age group.
Conclusions: The study establishes gestational age-specific reference data for DTI-derived AV intervals, which can be used for detection of subtle AV conduction anomalies in fetuses with maternal anti-Ro and anti-La autoantibodies.