Assessment Of Aortic Isthmus Blood Flow In Fetuses Of Mothers With Gestational Diabetes Mellitus

Gestational diabetes mellitus（GDM）,as a common complication of pregnancy,not only affects the health of pregnant women,but also seriously affects the growth and development of fetuses and their circulatory system.According to the International Association of Diabetes and Pregnancy Study Groups（IADPSG）standard,the average prevalence of GDM is 17.8%in the whole world.The high incidence rate of GDM also raises more stringent requirements for the development of medical technology.Therefore,it is necessary to monitor GDM patients and fetuses as comprehensively and accurately as we can.With the development of ultrasound technology in recent years,fetal echocardiography as a non-invasive means of examination,its value in evaluating fetal hemodynamics has been widely confirmed by various studies and clinical applications.A variety of anatomical parameters and echocardiographic parameters are available to evaluate the changes of fetal hemodynamics.The isthmus of the aortic（Ao I）is a segment of the aorta between the left subclavian artery and the descending aorta injected by the ductus arteriosus.With the changes of left and right ventricular contractility and their respective reloads,the isthmus"regulates"the blood flow passing through it at any time.Ao I blood flow can directly reflect the resistance difference between the upper and lower vessels of diaphragm,so it can be used to monitor fetal hemodynamics.What is more important thing is that Ao I as a monitoring index of fetal intrauterine status and postnatal development is gradually proposed.Isthmus flow index（IFI）is a semi-quantitative index first proposed by Ruskamp et al.It is obtained by dividing the sum of diastolic and systolic velocity time integral by systolic velocity time integral.It represents the proportion of left and right ventricular ejection and is related to load state and balance of brain and placenta.Therefore,the IFI value will change when hypoxia,increased placental resistance,decreased brain resistance or changes in cardiac preload and preload affect this equilibrium state.The clinical value of IFI in monitoring common pregnancy complications such as intrauterine growth restriction（IUGR）has been confirmed by many researches,but its value in monitoring fetal hemodynamics in GDM patients has not been reported yet.Therefore,the main purpose of this study is to explore the changes of IFI in fetal circulation of GDM and its potential clinical value.In this study,39 fetuses of GDM patients were selected as the disease group.The pregnant women were 20～35 years old,with an average of（30.18±5.33）years old.The gestational age measured by fetal ultrasound ranged from 24～37⁺⁶ weeks,with an average of（31.33±3.64）weeks.63 normal pregnant fetuses matched with the gestational age of the disease group were selected as the control group.The age of pregnant women ranged from 20 to35 years old,with an average of（30.76±3.89）years old.The gestational age measured by fetal ultrasound ranged from 24 to 37⁺⁶ weeks,with an average of（30.98±3.59）weeks.IFI was calculated by measuring and recording systolic velocity time integral（SVI）and diastolic velocity time integral（DVI）of all fetal aortic isthmus.IFI formula:IFI=（SVI+DVI）/SVI,to compare the difference of blood flow index of aortic isthmus between GDM fetuses and normal fetuses,and to analyze the regularity and characteristics of blood flow changes of aortic isthmus in GDM fetuses.The statistical software package SPSS 26.0 was used for data analysis;the measurement data was expressed by（（?）±S）;the difference between the fetal IFI of the disease group and the normal pregnancy group was analyzed by independent sample t-test.The difference was statistically significant（P<0.05）.Intraclass Correlation Coefficients（ICC）was used to evaluate the repeatability of intra-and inter observer measurements.The results are as follows:（1）There was no significant difference in maternal age,fetal ultrasound gestational age between the two groups（P>0.05）;（2）There was no significant difference Fetal ultrasound growth and development between the two groups（P>0.05）;（3）The fetal IFI of the disease group（average 1.182±0.034）was lower than that of the control group（average 1.308±0.070）,the difference was statistically significant（P<0.05）;compared with the two groups of fetal DVI,the fetal DVI of the disease group was significantly lower than that of the control group（P<0.05）;there was no significant difference in fetal SVI between the disease group and the control group（P>0.05）;（4）For IFI measurements,the intra observer and inter observer correlation coefficients were 0.921（95%confidence interval:0.81-0.93）and0.952（95%confidence interval:0.83-0.95）,respectively;（5）In this study,the fetal IFI of the control group decreased slightly with the increase of gestational age;Through the measurement and analysis of Doppler echocardiography,this study concluded that the fetal IFI value of GDM patients was lower than that of normal pregnancy.Compared with normal pregnant fetuses,the Ao I diastolic velocity time integral of GDM fetuses decreased,and the IFI value decreased accordingly.In this study,the fetal IFI of the control group decreased slightly with the increase of gestational age.There was no significant difference in the general information of pregnant women and fetal growth and development between the two groups.In conclusion,the measurement and analysis showed that the fetal aortic isthmus blood flow index of GDM patients was lower than that of normal pregnant fetuses,suggesting that this change may be related to the fetal hemodynamic changes caused by maternal metabolic changes in GDM patients.Fetal IFI can be used as an index to evaluate fetal hemodynamics and its changes,and IFI has higher reliability than other ultrasound indexes in evaluating fetal hemodynamics,which can provide more reliable parameters for clinicians’diagnosis and treatment,and provide new diagnosis and treatment ideas for early and timely intervention of GDM patients and their fetuses.In conclusion,IFI has great research and clinical value in the evaluation of fetal circulation.