The Clinical Value Of Ultrasonic Evaluate Hemodynamic Changes In Fetal Aortic Isthmus Of Preeclampsia Patients

Objective:To quantitative evaluate the characteristics and change rules in fetal aortic isthmus(AOI)of preeclampsia(PE)through the analysis of isthmus flow index(IFI)and isthmic systolic index(ISI).We also aimed to analyze its clinical value in the diagnosis of hemodynamic changes of PE fetal,to find some clues and evidences for fetal intrauterine hypoxia.Methods:From March 2017 to December 2017 in our prenatal ultrasound examinations of singleton pregnancy,50 pregnant women complicating PE,out of 12 cases,into a group of 38 cases and 38 controls matched by gestational age.The fetal AOI Doppler waveforms were obtained from both groups.The middle cerebral artery(MCA),umbilical artery(UA)and ductus venosus(DV)Doppler waveforms were obtained from study group.Systolic flow velocity time integrals(S),diastolic flow velocity time integrals(D),peak systolic velocity(PSV)and systolic nadir(Ns)were measured on all AOI Doppler waveforms.We also measured the pulsatility index(PI)in MCA and UA,calculated the proportions of absent or reversed end diastolic flow in AOI and UA and the proportions of absent or reversed in ductus venosus atrial contraction wave(DV-a).IFI was calculated as follows:IFI=(S+D)/S.ISI was derived from the ratio Ns/PSV.An cerebroplacental ratio(CPR)was calculated as follows:MCA-PI/UA-PI.Ruskamp classified the IFI as follows:typeI,IFI≥1;type II,1>IFI≥0;type III,IFI<0.Paired sample t-test was applied on IFI and ISI values.Chi-square test was performed on count data.The correlation between CPR and IFI were analysised by linear correlation.The reliability of Doppler blood flow measurements was assessed by calculating intraclass correlation coefficients.Results:Excellent ICCs for the intra-and interobserver assessments in IFI,ISI,CPR were:0.926,0.990,0.962 and 0.818,0.815,0.883,respectively.All of the normal fetal have a IFI>1.2,antegrade flow was found during the entire cardiac cycle in the aortic isthmus.The IFI in the study group showed a significant decrease compared to the control group,in the study group typeI 21cases,typeII 10 cases,typeIII 7cases,The IFI between the two groups showed a significant difference(t=4.46,P<0.001).An inverse correlation was found between ISI and gestational age r=-0.757(P<0.001).a fall of ISI towards a mean value of zero around 30 weeks,This trend continues thereafter,and a brief reversal of flow towards the end of gestation is observed.The ISI also showed a significant decrease compared to the control group((t=3.08,P<0.004)).The proportions of absent or reversed end diastolic flow in AOI and UA and the proportions of absent or reversed in DV-a were 44.74%(17/38)、13.16%(5/38)、0%(0/38),respectively,which showed significant differences(?~2=23.76,P<0.005).There is a linear positive correlation relationship between IFI and CPR(r=0.50,P<0.002).Conclusions:The forward net flow is decreased in the study group,absent or reversed end diastolic flow in AOI was found.When IFI≤1 we could predict that the hemodynamic changes and fetal circulation lack of oxygen.The ISI in the study group showed a significant decrease compared to the control group,which is also a indicator of hemodynamic changes.We proposed that AOI is a particularly sensitive indicator of fetal hemodynamic changes.The detection of AOI blood flow Doppler waveforms can detect early hemodynamic changes in fetal that lack of oxygen,which can provide evidence for earlier diagnosis of fetal lack of oxygen.