Atrial dominance in the human embryonic heart: a study of cardiac function at 6-10 weeks of gestation.

Objective To investigate the difference in forces developed by atrial and ventricular myocardium during contraction in human embryos using a novel method. Methods This was a cross-sectional study of 115 pregnancies examined at 6–10 weeks of gestation. Ventricular inflow and outflow velocities were obtained by Doppler echocardiography and the relative force development was evaluated by calculating the ratio between atrial and ventricular ejection force (EF). Results Data from 97 embryos with monophasic ventricular filling were analyzed. Both inflow and outflow cardiac velocities increased with advancing gestational age (P < 0.001). The mean peak inflow velocity (31.7 ± 10.2 cm/s) was significantly higher (P < 0.0001) than the outflow velocity (19.6 ± 6.1 cm/s). The EFinflow/EFoutflow ratio was more than 1.0 in all but four (96%) cases. Conclusion Our study indicates the possibility of atrial dominance in the embryonic period of heart development, which may have clinical implications, as deviations from this normal pattern may indicate human embryonic cardiac dysfunction. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd.