Fetal M-mode echocardiography of atria in normal heart anatomy and no functional abnormalities

Introduction
M-mode echocardiography at the atrial level is only possible during prenatal life. The aim of the study was to evaluate the M-mode parameters of RA/LA in fetal normal heart anatomy (NHA) and without functional anomalies (NHS).

Material and methods
M-mode echocardiography of RA/LA patterns were analysed in 32 fetuses, with mean gestational age 27.7 ±3.7 weeks. It was a retrospective cross-sectional analysis. Using 2-D ECHO a four-chamber view was obtained, and M-mode was put perpendicular to atrial walls.

Results
Typical pattern of M-mode echo RA/LA was found in fetuses with NHA and NHS: RA wall contractions were more prominent than LA wall contractions in 66%, they presented with an equal amplitude of contractions in 25%, and with only RA contractions in 9%. The interatrial septum was in the middle of the space between both atrial walls. The septum primum (FO flap) was moving always within the space of the LA presenting a typical trace: during atrial wall contractions it was fast moving towards the RA wall, and during atrial diastole it showed slower biphasic trace in 79% or other trace in 21%.

Conclusions
M-mode echo of RA/LA in fetuses with NHA and NHS showed a typical pattern of atrial wall excursions, FO valve movement in atrial systole and atrial diastole, and position of atrial septum.