Noninvasive Determination Of The Fetal Cardiac Interatrial Pressure Gradients By Doppler Ultrasonography: Preliminary Results

Objective: In 2000, Johnson et al. measured the atrial pressures puncturing the atria invasively in 19 fetuses that will be terminated. In this study, it is aimed to define the fetal cardiac interatrial pressure gradient noninvasively. The pressure gradients were calculated using the ductus venosus (DV) and pulmonary vein (PV) blood flow velocities and Bernoulli equation for flowing fluids. Methods: "S," "a," and the time-averaged maximum velocities in both veins of 246 fetuses were used in the simplified Bernoulli equation; Delta p=4. Additionally, the umbilical vein maximum velocity is measured in order to calculate ducto-umbilical pressure gradient. Results: The average interatrial pressure gradient was biggest in the ventricular systole and the least gradient was in the atrial systole of a cardiac cycle. The pressure gradient changes throughout the second and the third trimester have four periods with two increases and two decreases. Conclusions: The interatrial and ducto-umbilical pressure gradients can be measured noninvasively in order to follow the hemodynamic of the fetal circulatory system.