EP09.55: Reference z scores and percentile values for the best use of the fetal AV internal in clinical practice

To determine the 10th, 50th, 90th and 95th percentiles for the mechanical PR interval (AV interval) of the heart of normal fetuses with gestational ages between 16 weeks and 33 weeks and 6 days, using two-dimensional echocardiography with pulsed Doppler, and to develop a Z-score equation to facilitate the assessment of normality of this measurement. Multicentre, prospective, cross-sectional study with normal fetuses between 16 weeks and 33 weeks and 6 days of gestation. All the pregnant women underwent a complete fetal echocardiogram and pulsed Doppler curves were collected in the five-chamber plane. The pulsed Doppler sample was positioned between the left ventricular inflow and outflow tracts. The Doppler flow pattern of the mitral valve and the aortic valve were determined simultaneously on the same tracing. The AV interval was measured from the beginning of the A wave of the mitral valve to the beginning of the systolic flow of the aortic valve. Analysis of the normality of the AV interval values was carried out. The AV interval measurement showed a normal distribution, a behaviour independent of gestational age. Thus, the Z-score equation was developed from the mean and standard deviation of the original study measurements. AV interval Z score: (MPI measurement - 111,3)/8,6. The AV interval showed a tendency to decrease in relation to heart rate, according to the Pearson correlation (weak correlation r: - 0.2, but statistically significant p < 0.001). The present study established reference values, percentiles and developed Z-score equation for the best use of fetal AV interval in clinical practice.