A Preliminary Study Of The Evaluation Of Heart Function In Fetus With Tetralogy Of Fallot By Velocity Vector Imaging

Purpose: Use Velocity vector imaging(VVI)technology to evaluate the changes of left and right ventricles myocardial function of fetus with Tetralogy of Fallot(TOF)in the period of subclinical cardiac dysfunction.Methods: The study selected 40 fetuses diagnosed with tetralogy of Fallot in the Department of Ultrasound Diagnosis,Union Hospital of Tongji Medical College,Huazhong University of Science and Technology from January 2016 to August 2018.Another 40 normal fetuses matched to the gestational age of the case group were also enrolled(control group).Firstly,All of these fetuses in both case group and control group were accepted routine cardiac echocardiography,and the routine measurement parameters of the heart were obtained: the transverse diameter of the left atrium(LVwidth),the transverse diameter of the right atrium(RA-Width),and the transverse diameter of the left ventricle(LV-Width),right ventricular transverse diameter(RVWidth),intraocular diameter(FO-diameter),ascending aorta lumen diameter(Ascend Aorta-diameter),fetal heart rate(HR).The standard four-chamber view of 80 fetuses was analyzed by VVI software offline,A series of myocardial mechanics parameters of left and right ventricles were measured,including the globle and each segments peak systolic velocity(Vs),peak diastolic velocity(Vd),strain(S),systolic strain rate(SRs)and diastolic strain rate(SRd)of both left and right ventricles.The normal measurement parameters of the fetal heart and the parameters of myocardial strain obtained by VVI software analysis of the TOF group was compared with the control group,and analysis whether the differences between the two groups have statistical significance(p<0.05 was meaningful);Results: 1.Echocardiographic measurement parameters of the fetal in the TOF group:(1)The size parameters of the TOF group(LA-width,RA-width,LV-width,RV-width)were not statistically different from those in the normal control group(p >0.05);(2)There was no significant difference in fetal HR,LVEF and RVEF between the two groups.(p>0.05);(3)The inner diameter of the foveal hole(FO-diameter)and the diameter of the ascending aorta(AAO-diameter)in the TOF group were larger than those in the normal control group,and the difference was statistically significant.(p<0.05);VVI related parameters:(1)TOF group fetal right ventricular global longitudinal systolic peak velocity(GLVs),overall longitudinal diastolic peak velocity(GLVd),overall longitudinal strain(GLS),overall longitudinal systolic strain rate(GLSRs)and overall longitudinal diastolic strain rate(GLSRd)are lower than the normal control group,the difference is statistically significant(p<0.05);(2)Strain(S),systolic strain rate(SRs),diastolic strain rate(SRd),right ventricular wall segment,apical segment,and ventricular systolic systolic peak velocity(Vs),right The peak velocity(Vd)of the basal segment,middle segment,apical segment and ventricular septal segment of the ventricular wall was lower than that of the normal control group,and the difference was statistically significant(p<0.05);(3)The total longitudinal diastolic peak velocity(GLVd),strain(GLS)and diastolic strain rate(GLSRd)of the left ventricle in the TOF group were lower than those in the normal group(p<0.05);(4)The strain(S)in the middle segment of the left ventricular septum and the diastolic strain rate(SRd)in the apical segment of the left ventricular wall were lower than those in the normal group(p<0.05);(5)There were no significant differences in other VVI parameters between the left and right ventricles and the segments(p>0.05).Conclusion: The heart size and ventricular ejection fraction of children with TOF during fetal period were not significantly different from those of normal fetuses of the same gestational age,but the contraction and diastolic function of the right ventricle could be significantly reduced during the fetal period.Although the left heart function of the TOF fetus is not as obvious as the right ventricle,some VVI parameters have also been declined.VVI technology can be used to evaluate the changes of left and right ventricular global and regional myocardial function in the fetus of tetralogy of Fallot in the period of subclinical cardiac dysfunction,to achieve the purpose of early diagnosis and intervention.