The Value Of Myocardial Performance Index And Doppler Parameters In Predicting Fetal Death After The Treatment Of TTTS

ObjectiveWith the widespread use of assisted reproductive technology and the increase of older pregnant women,the incidence of twin pregnancy is increasing,of which about30%are monochorionic diamniotic（MCDA）.In the process of growth and development of monochorionic twins,twins are prone to special complications such as twin to twin transfusion syndrome（TTTS）,selective intrauterine growth restriction（s IUGR）,twin anemiapolycythemia sequence（TAPS）and so on.TTTS is a common serious complication of monochorionic（MC）twin pregnancy,accounting for about 10%to 15%of MC pregnancy.The prenatal mortality rate of untreated TTTS is as high as 80%to 90%.It is pointed out in the guidelines for diagnosis,treatment and Health Care of Twin to Twin Transfusion Syndrome（2020）by the Twin pregnancy Committee of China Maternal and Child Health Association that fetoscopic laser surgery（FLS）is the first choice for the treatment of TTTS.It is a treatment to remove the etiology and can significantly improve the prognosis of fetal with TTTS.Many studies have shown that cardiac dysfunction is an important factor in the death of children with TTTS,but the Quintero staging system,which is commonly used to evaluate the severity of TTTS,can not reflect the changes of fetal cardiovascular function and is not completely related to fetal prognosis.For this reason,domestic and abroad studies have used myocardial performance index（MPI）and some scoring systems to evaluate fetal cardiac function,such as Children’s Hospital of Philadelphia（CHOP）score,cardiovascular profile score（CVPS）,Cincinnati score and so on.Some studies have reported that these indexes can predict intrauterine fetal demise（IUFD）and neonatal outcome,However,the use of indicators and prediction results are different.The purpose of this study is to explore the predictive value of fetal and neonatal death by prospectively detecting fetal MPI,CVPS and blood flow Doppler parameters before and after laser surgery.Materials and Methods1 Research objects and groupingA total of 61 pregnant women with TTTS diagnosed as MCDA in the third affiliated Hospital of Zhengzhou University from June 2019 to August 2020 were selected and treated with selective laser photocoagulation of communicating vessels（SLPCV）for the first time.The pregnant women were 16-39 years old,with an average age of（27.98±4.71）years.The gestational ages were 15-29 weeks,with an average of（20.86±2.95）weeks.The diagnostic criteria of TTTS are as follows:severe amniotic fluid inconsistency in monochorionic twin pregnancy,that is,the deepest vertical pocket（DVP）of one fetus（blood recipient）≥8cm before 20 weeks of pregnancy,and the other fetus（blood donor）DVP≤2cm.The severity of the disease was staged according to the Quintero staging system.The gestational age was determined by the last menstruation or by ultrasonic examination in early pregnancy,and the chorionic and amniotic properties of MCDA were determined by ultrasonic examination in early pregnancy.2 Research MethodsTwo fetuses of TTTS were examined by fetal echocardiography within 24 hours before operation,7 days after operation,14 days after operation,30 days after operation and 60 days after operation.The left and right ventricular myocardial performance index（LV-MPI and RV-MPI）of the two fetuses were measured and converted into z scores by SPSS software,CVPS was obtained,the end diastolic blood flow pattern of umbilical artery（UA）was monitored,the peak systolic velocity of middle cerebral artery was measured and converted to mom value(MCA-PSV_{Mo M}),the flow pattern of a wave in venous catheter（DV a wave）was monitored and the cerebral placental rate（CPR）was calculated,respectively.Fetal death is defined as intrauterine fetal death and neonatal death within 28 days of birth.3 Statistical methodsThe data were analyzed by SPSS 18.0 software.Shapiro-Wilk test is used to evaluate the normality of the measured data.Continuous variables are expressed by mean±standard deviation(variance（（?）±s）.T-test is used to compare normal distribution between the two groups,and Mann-Whitney U test is used to compare non-normal distribution.Fisher exact chi-square test or chi-square test was used for univariate analysis of classified data.Univariate and multivariate Logistic regression analysis was used to identify the factors that could predict fetal and neonatal death in TTTS,and the receiver operator characteristic curves（ROC curves）were drawn respectively to obtain the best cutoff value to evaluate the predictive value of different factors on fetal death.According to the best cutoff value,the death group was analyzed by subgroup analysis.The difference was statistically significant（P<0.05）.Results4.1 61 cases of TTTS were included in the study.The overall survival rate at28 days after birth was 71.3%（87/122）,at least one fetus survived 78.7%（48/61）,both twins survived 63.9%（39/61）,only one fetus survived 14.8%（9/61）,both twins died 21.3%（13/61）,recipients survived 73.8%（45/61）,and blood donors survived68.9%（42/61）.The survival rates of twins in Quintero I～IV stage were 82.4%,66.7%,47.6%and 63.6%,respectively,the survival rates of blood receiving fetuses were88.3%,66.7%,66.6%and 72.7%,respectively,and the survival rates of blood-fed fetuses were 82.4%,66.7%,47.6%and 90.9%,respectively.4.2 The six indexes that can predict the death of recipients are as follows:the RV-MPI z score of recipients before operation,the best cut-off value is-0.03,and the corresponding RV-MPI is 0.58.7 days after operation,the best cut-off value of RV-MPI z score was 0.42 and the corresponding RV-MPI was 0.56.The best cut-off value of CVPS was 9.5 on the 7th day after operation,and the end-diastolic blood flow signal of umbilical artery absent or reserved end diastolic flow（UA A/REDF）on the 7th day after operation.The best cut-off value of RV-MPI z score of blood recipients was 0.20 at 14 days after operation,corresponding to RV-MPI of 0.52,and UA A/REDF of blood donors at 14 days after operation（P<0.05）.The best predictor is RV-MPI z score of recipients before operation.4.3 The seven indexes that can predict the death of blood donors are:RV-MPI z score of recipients before operation,the best cut-off value is-0.19,corresponding to RV-MPI is 0.55,and the best cut-off value of CVPS is 9.5 before operation.7 days after operation,the best cut-off value of RV-MPI z score of recipients was 0.68,corresponding to RV-MPI was 0.60.7 days after operation,the best cut-off value of RV-MPI z score of donors was 0.078,corresponding to RV-MPI was 0.58,and the best cut-off value of CVPS of blood donors 7 days after operation was 9.5.The best cut-off value of RV-MPI z score of blood donors at 14 days after operation was 0.14,corresponding to RV-MPI of 0.51,and UAA/REDF of blood donors at 14 days after operation（P<0.05）.The best predictor is UA A/REDF of blood donors 14 days after operation.ConclusionMyocardial performance index combined with doppler parameters has important clinical value in predicting the death of twin to twin transfusion syndrome after laser treatment.It is necessary to have regular fetal echocardiography before and after TTTS laser treatment,which should last at least 14 days or longer after operation.