Measurement of epicardial fat thickness
Epicardial fat thickness was measured on the free wall of the right
ventricle using a technique that showed good correlation with the values
found on MRI [12, 26]. According to this method, the apical
five-chamber view of the fetal heart was first obtained in a transverse
plane through the fetal thorax and left ventricular outflow tract (LVOT)
as the optimal view to visualize the hypoechoic space between the
epicardial surface and the parietal pericardium at the right ventricle.
To improve reproducibility and standardize measurements, a reference
line was drawn as an anatomic landmark extending from the descending
aorta through the annulus of the aortic valve and then upward to a point
on the free wall of the right ventricle. The hypoechoic area at this
point was used to measure EFT. Color Doppler was used to distinguish
epicardial fat and pericardial effusion. A frozen real-time
ultrasonographic image was acquired during end systole, and the
hypoechoic area was magnified as much as possible. Then, the EFT was
measured across the reference line by placing the caliper from the
inside to the outside (Figure1). Measurements were taken three times and
the average values were used for the final analysis.