Background Umbilical cord around neck,a common obstetric complication,affects fetal hemodynamics.Does it influence fetal cardiac functions? The purpose of this study was to investigate the left and right ventricular systolic and diastolic functions of fetuses with umbilical cord around neck in the third trimester by applying velocity vector imaging (VVI).Methods Thirty-five cases of fetuses with umbilical cord around neck whose gestational ages from 35 to 40 weeks were selected,including 20 cases of umbilical artery ratio of the highest systolic velocity (S) to the lowest diastolic velocity (D) (S/D) ＜3.0 and 15 cases of umbilical artery S/D ≥3.0,while 20 cases of normal fetuses of 35-40 gestational weeks were selected as the control group.The changes in longitudinal velocity,strain,and strain rate of fetal left and right ventricle in systole and diastole in two groups,and the changes in fetal cardiac function under the situation of umbilical cord around neck were analyzed.Results Longitudinal strain and strain rate overall of fetal left and right ventricle in systole and diastole were less in fetuses with umbilical artery S/D ≥3.0 and umbilical cord around neck than those in fetuses with umbilical artery S/D ＜3.0and those in control group (P ＜0.05); there was no significant difference (P ＞0.05) in longitudinal strain and strain rate overall of fetal left and right ventricle in systole and diastole between fetuses with umbilical artery S/D ＜3.0 and those in control group.Conclusions Left and right ventricular systolic and diastolic dysfunction was detected in fetuses with umbilical cord around neck and umbilical artery S/D ≥3.0.WI could sensitively respond to cardiac function changes in fetuses with umbilical cord around neck,which provides another valuable method in the evaluation of fetal cardiac function.