Evaluation Of The Changes Of Hemodynamics And Cardiac Function In Fetuses With Right Ventricular Outflow Tract Obstruction By Echocaridiography And Two-dimension Speckle Traking Imaging

Objective: Performed echocardiographic studies on fetuses with various types of right ventricular outflow tract obstruction(RVOTO),analyzed the hemodynamic changes caused by the abnormalities in the heart structure of RVOTO fetuses,and evaluated the corresponding myocardial mechanical changes by two-dimensional speckle tracking imaging(2D-STI).The aim of this study was to reveal the unique circulation characteristics and cardiac function changes of fetuses with various types of RVOTO more comprehensively and deeply,and to explore the clinical application value of echocardiography combined with new technology in the evaluation of fetal congenital heart disease.Methods: 110 singleton fetuses diagnosed as RVOTO by prenatal echocardiography in the First Affiliated Hospital of China Medical University and Shengjing Hospital from January 2013 to December 2020(gestational age 20 to 34 weeks,average gestational age26.8±3.3 weeks)were enrolled in this study,who were divided into group A and group B according to whether they were combined with unrestricted ventricular shunt.The gestational age(GA)matched 135 singleton fetuses were enrolled in control group.Hemodynamic parameters of fetal pulmonary artery,ductus arteriosus(DA),ductus venosus(DV),middle cerebral artery(MCA)and umbilical artery(UA)were evaluated by Doppler echocardiography,including the maximal velocity of pulmonary valve(PVmax),acceleration time(ACT)and ejection time(ET)of pulmonary artery;the peak ventricular systolic velocity(Vs),peak ventricular early diastolic velocity(Vd),peak atrial systolic velocity(Va)and peak velocity index for veins(PVIV)of DV;and the pulsatility index(PI)of MCA and UA.The cerebroplacental ratio(CPR)was calculated,CPR=MCA-PI/ UAPI.The diameters of pulmonary(PA)and aortic(AO)valve annulus at end-systole were measured by 2D echocardiography,and calculate the PA/AO ratio and PA Z-score.The differences of the hemodynamic parameters of the fetuses between the A and B case groups and the GA matched controls were compared.According to the above results of RVOTO fetal hemodynamic research and related research conclusions,group A was divided into severe RVOTO group and mild-moderate RVOTO group according to whether there was PA /AO < 0.6 or PA Z-score <-3 and retrograde perfusion of ductus arteriosus.Group B was divided into severe RVOTO group and mild-moderate RVOTO group according to fetal pulmonary valve morphology,opening and closing conditions and related echocardiographic performance.The 2D-STI analysis software was used to post-process and analyze the movie clips of fetal standard four-chamber view of the fetuses in the severe RVOTO group,mild-o moderate RVOTO group and the control group,and obtained the segmental and global longitudinal peak systolic strain(S),systolic strain rate(SRs)and diastolic strain rate(SRd)of left and right ventricular walls.The interventricular synchronization parameter was calculated in the strain-time curve of the lateral wall of the left ventricle and the free wall of the right ventricle.The left ventricular ejection fraction(LVEF)was calculated by 2D Simpson method,and the right ventricular fraction area change(RVFAC)was measured by 2D echocardiography.The differences in the cardiac function parameters obtained by2 D echocardiography and 2D-STI were compared between the severe RVOTO group,the mild to moderate RVOTO group and the GA matched controls.Results: 1.92(83.6%)cases in the case group and 115(85.2%)fetuses in the normal control group obtained all the ultrasound data required for this study.2.The PA/AO ratio of RVOTO fetuses in group A and B was lower than that in the GAmatched control group(P<0.01),and the absolute value of PA Z-score was higher than that in the control group(P<0.01);Except for the fetuses with pulmonary atresia,PVmax of the case group was faster than that of the GA-matched control group(P<0.01),ACT and ET were shorter than those of the control group(P<0.01).3.Retrograde perfusion of ductus arteriosus occured both in 16 case group A and B.4.Among 54 RVOTO cases in the group A:(1)The blood flow of DV,MCA and UA in 15 severe RVOTO fetuses with PA/AO<0.6 or PA Z-score<-3 and retrograde perfusion of ductus arteriosus was significantly different from that in 39 GA-matched mild-moderate RVOTO fetuses and control group,manifested as a decrease in DV-Va,an increase in DV-PVIV(P<0.05);a decrease in MCA-PI,CPR,and an increase in UA-PI(P<0.05).(2)Compared with GA-matched control group,MCA-PI and CPR of mild-moderate RVOTO fetuses decreased,while the UA-PI increased(P<0.05);there was no significant difference in DV blood flow spectrum parameters(P>0.05).5.Among 38 RVOTO cases in the group B:(1)The blood flow of DV,MCA,UA and DA in 16 fetuses with pulmonary artery severe stenosis or atresia was significantly different from that in 22 GA-matched fetuses with mild-moderate stenosis of pulmonary artery and the control group,which showed that DVVa decreased(P<0.01),while DV-PVIV increased(P<0.01);absent or reversed enddiastolic flow(AREDF)of DV occurred in 12 cases;MCA-PI and CPR decreased,UA-PI increased(P<0.05),and retrograde perfusion of ductus arteriosus occured in all severe stenosis or atresia of pulmonary cases.(2)The DV-Va of the fetuses with mild to moderate pulmonary artery stenosis was lower than that of the GA-matched control fetuses,and the DV-PVIV increased(P<0.05).There was no significant difference in MCA-PI,UA-PI and CPR between mild-moderate RVOTO cases and control group(P>0.05).6.The left and right ventricular myocardial mechanics characteristics in 115 normal fetuses:(1)The longitudinal S,SRs and SRd between the segments of the left ventricle wall were not significantly different(P>0.05);while the S and SRs between the segments of the right ventricular free wall decreased sequentially from the basal segment to the apical segment(P<0.05),and there was no significant difference in longitudinal SRd between each segment of the right ventricular free wall(P>0.05).(2)The GLS of the left and right ventricular walls was positively correlated with GA,and the GLSRs and GLSRd of the left and right ventricular walls were not correlated with GA.(3)There was no significant difference in GLS,GLSRs and GLSRd between the left and right ventricular walls(P>0.05).(4)The normal reference range of interventricular systolic synchrony parameter was 9.24 ±4.48ms(2?22ms),and there was no correlation with gestational age.7.The left and right ventricular myocardial mechanics parameters in 92 RVOTO fetuses:(1)2D-STI analysis showed that the GLS,GLSRs and GLSRd of the left and right ventricular walls of cases with severe RVOTO were lower than those of GA-matched mildmoderate RVOTO cases and control group(P<0.05).However,the LVEF of severe RVOTO fetuses measured by two-dimensional Simpson method was not different from the other two groups.In severe RVOTO fetuses,interventricular systolic dyssynchrony existed simultaneously.(2)The GLSRd of right ventricular wall in mild-moderate RVOTO cases was lower than GA-matched normal controls(P<0.05).There was no significant difference in GLS,GLSRs of right ventricular wall and GLS,GLSRs,GLSRd of left ventricular wall between the two groups(P > 0.05).There is no difference in the interventricular systolic dyssynchrony between fetuses with mild-moderate RVOTO and the normal controls.8.The results of multivariate logistic regression analysis showed that PA/AO < 0.6 and retrograde perfusion of ductus arteriosus was significantly correlated with the decreased GLS of the left and right ventricular walls in RVOTO fetuses.The area under ROC curve of PA/AO < 0.6 for predicting the right ventricular and left ventricular systolic dysfunction of group A RVOTO fetuses were 0.860(0.95CI:0.757,0.962),0.801(0.95CI:0.672,0.930),respectively;the sensitivity and specificity were 88.9%,66.7% and 83.8%,58.8%,respectively.The area under ROC curve of PA/AO < 0.6 for predicting the right ventricular and left ventricular systolic dysfunction of group B RVOTO fetuses were 0.707(0.95CI:0.515,0.866),0.703(0.95CI:0.562,0.881),respectively;the sensitivity and specificity were 76.2%,58.8% and 76.0%,38.5%,respectively.Conclusion: 1.Comprehensive evaluation of the blood flow changes of DA,UV,MCA and UA in RVOTO fetuses can reflect their hemodynamic changes more deeply.When RVOTO fetuses were with severe obstruction or without unrestricted ventricular shunt,the DV blood flow spectrum changed significantly.Retrograde perfusion of ductus arteriosus could indicate the degree of obstruction of the RVOTO fetus.The cerebral blood perfusion was maintained by compensatory cerebral artery dilatation and umbilical artery contraction when the cerebral blood oxygen saturation or blood flow decreased in RVOTO fetuses.2.Systolic and diastolic dysfunction of both ventricles occurred in the severe RVOTO cases,accompanied by the interventricular systolic dyssynchrony.However,fetuses with mild-moderate RVOTO only showed reduced right ventricular diastolic function.3.PA/AO < 0.6 can be more sensitive to predict left and right ventricular systolic dysfunction of RVOTO fetuses with ventricular level unrestricted shunt,and it is limited in predicting left and right ventricular systolic dysfunction of RVOTO fetuses with intact ventricular septum.4.The global longitudinal strain and strain rate of ventricular wall obtained by 2D-STI can reflect the early changes of fetal ventricular function more sensitively than traditional twodimensional ultrasound.Interventricular systolic synchrony parameter derived from 2DSTI was a potential important method in the clinical assessment of the fetal cardiac systolic function.