Abstract:

Objective　To investigate the application and the influencing factors of velocity vector imaging for evaluating of myocardial mechanics in the normal fetal ventricles.　Methods　Two-dimensional 4-chamber images of the heart (n=147) were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, and strain rate were performed on the right and left ventricle. Comparison was made between each segmental and global measurement respectively. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.　Results　(1) The left and right ventricular velocities decreased from the base to the apex segment (P<0.05). The strain and strain rate showed no significant difference among global and each segmental measurement (P>0.05). (2) The global velocities had significant positive correlation with increasing gestational week (left ventricle r=0.662，P<0.05；right ventricle r=0.732，P<0.05). The strain and strain rate had no significant correlation with gestational age (P>0.05). (3) There was significant correlation between the global strain rate and fetal heart rate (left ventricle r=0.454，P<0.05；right ventricle r=0.465，P<0.05). The strain and velocity had no significant correlation with the fetal heart rate (P>0.05). 　Conclusions　VVI is a newly technique for quantitating global and segmental fetal cardiac function.

Key words:  Foetus, The cardiac, Velocity vector imaging, Ultrasound