Application Of Echocardiography And Computational Dynamic Fluid Technology In The Diagnosis Of Aortic Coarctation

PART ⅠPrenatal echocardiography to estimate the risk for coarctation of the aorta:(CoA)-From fetal to newborn lifeObjective:This study aimed to develop a coarctation probability model incorporating prenatal cardiac sonographic markers to estimate the probability of an antenatal diagnosis of CoA.Methods:A multicenter retrospective analysis was performed on 148 fetuses with suspected prenatal coarctation of the aorta(CoA)from May 2015 to October 2020 as an investigation cohort for creating a multiparametric model and internal validation.Exclusion criteria included pregnancy termination,intrauterine death,poor image quality,unavailability of postpartum follow-up data,and concomitant major intracardiac malformations.Record the following parameters through the workstation:①generic parameters of echocardiography:right ventricle end-diastolic dimensions(RVEDD),left ventricle end-diastolic dimensions(LVEDD)、ascending aorta(AAO)、aortic isthmus(AoI)、main pulmonary artery(MPA)、ascending aorta peak velocity(VAO).②Morphological parameters of aortic arch：left common carotid artery to left subclavian artery distance/distal transverse arch(LCCA-LSCA)/DT、measurements of the(AAO-DAO)angle,(TAO-DAO)angle.③Baseline characteristics:Check the gestational age,gestational age at delivery,and gender after birth.Categorized them into three subgroups according to the follow-up outcome:(1)severe CoA:symptomatic CoA and surgery within the first 3 months;(2)mild CoA:surgery 3months after birth;(3)falsepositive CoA:not requiring surgery.One-way ANOVA and Logistic regression analysis were used to determine the independent risk factors for predicting postpartum CoA surgery,and the nomogram model was established.The Bootstrap method was used to verify the model internally.The discriminative degree of the model was evaluated by C-index.90 cases of normal control group were selected to analyze the differences of morphological parameters of aortic arch between the two cohorts.A total of 136 fetuses suspected of CoA from November 2019 to November 2021 were prospectively collected as the validation cohort for external validation of the model.Results:1.Investigation cohort results:A total of 89 fetuses were followed up for(4.2±2.6 years).At the end of follow-up,44 fetuses(49%)were diagnosed with CoA after birth,and 15 fetuses(16.8%)received CoA surgery within 3 months after birth.Twenty-nine fetuses(32.2%)received CoA surgery 3 months after birth,the remaining 45 fetuses(50.6%)did not receive aortic surgical intervention after birth.The results of univariate analysis showed that Z-VAO,Z-AAO,RVEDD/LVEDD ratio,LCCA-LSCA/DT ratio and AAO-DAO Angle were significantly different among the three subgroups(P<0.05).Small ventricular septal defect(VSD<4mm)was more common in the mild group,but there was no significant difference among the three groups(P>0.05).On the basis of univariate analysis results,combined with clinical experience,logistic multivariate regression analysis was performed on the variables with statistically significant differences.The results showed that LCCA-LSCA/DT(OR=7.1,CI:2.6-19.3),Z-VAO(OR=1.9,CI:1.3-3.1)and VSD(OR=5.0,CI:1.6-15.8)were independent risk factors for CoA surgery.The prediction accuracy of the model was 75.6%,the Boostrap verification was used for internal validation,and the results were good(P=0.87,C-index=0.85).Compared with the normal control group,the ratio of LCCA-LSCA/DT and the angle of AAODAO in the severe group were higher compared with the other groups(P<0.05).2.Results of the validation cohort:86 fetuses were followed up for(4.0±2.3 years),and 30 fetuses(35%)received CoA surgery after birth.The external validation results of the model were effective(P=0.98,C-index=0.79).3.Risk stratification analysis:according to the probability value(P)calculated by the model,it is suggested that people with P<15%are low-risk groups;Those with P values between 15%-60%were at moderate and low risk and needed imaging follow-up observation.P>60%were at high risk and required close hospitalization until the closure of the PDA.Conclusions:This model performs well in predicting whether the fetus with suspected CoA needs surgical intervention after delivery.It can be used for the risk assessment of CoA before and after delivery,and can be implemented in the fetal multidisciplinary diagnosis and treatment(MDT)model,which is of great significance for exploring the integrated management strategy before and after delivery.PART ⅡCTA-Based computational fluid dynamics Estimation of Pressure Gradients Across a CoAObjective:To evaluated the application value of computational fluid dynamics(CFD)simulation technology in non-invasive evaluation of pressure gradients in coarctation of aorta(CoA)based on CTA.Methods:We reviewed 11 patients who received interventional treatment with CoA in Shandong Provincial Hospital from May 2015 to February 2022.The inclusion criteria were as follows:(1)brachial-ankle blood pressure difference≥20 mmHg(1mmHg=0.133KPa);(2)CoA was confirmed by echocardiography and aortic CTA,and interventional therapy was performed;Exclusion criteria:(1)Combined with other diseases,such as heart failure,LVEF≤45%;(2)The examination interval time of CTA and echocardiography between preoperative and postoperative examination was more than 2 weeks;(3)with patent ductus arteriosus and extensive collateral circulation;(4)Patients with lower extremity arterial embolism,thromboangiitis obliterans,takayasu arteritis and other diseases causing lower extremity ischemia;(5)CFD model optimization fails and finite element analysis cannot be carried out.Low-dose retrospective ECG-gated CTA of thoracic aorta was performed by dualsource CT,and the peak exposure time window was set at the 40%R-R interval using ECGgated current regulation technology.Two radiologists independently analyzed the reconstructed CTA images of the patients at the first diagnosis,and the following parameters were collected in the single-phase images(40%R-R interval):(1)The maximum internal diameter of the posterior transverse arch(D1),the maximum internal diameter of the isthmus(D2)and the maximum internal diameter of the distal constricted descending aorta(D3)in each cardiac cycle image;(2)Distribution of collateral branches;(3)Combined with other intracardiac malformations.The velocity(Vmax,m/s),pressure gradients(PG max,mmHg),maximum peak aortic valve velocity(Vmax,m/s),and left ventricular ejection fraction(LVEF,%)were obtained by echocardiography.The forward flow velocity(Vmax,m/s)and maximum pressure gradients(PG max,mmHg)of the left common carotid artery,left subclavian artery,brachiocephalic trunk and abdominal aorta were obtained by vascular ultrasound.Before and after interventional therapy,fasting venous blood was collected from all patients to detect serum creatinine(Scr),glomerular filtration rate(eGFR),alanine aminotransferase(ALT)and blood urea nitrogen(BUN).The above data were obtained by consulting the cases.Mimics Medical 21.0 software was used for three-dimensional reconstruction to obtain the three-dimensional structure of aortic arch anatomical system and optimize the model.According to the set boundary conditions,the reconstructed vascular geometric model was imported into ANSYS Work bench for hemodynamic numerical calculation of blood in aortic arch.The visualization results of blood flow velocity field distribution,pressure and stress distribution were obtained,and the calculated results were verified with the pressure gradients of intraoperative catheter measurement at the constriction site.Results:9 patients were included in the analysis,including 5 males(55.6%)and 4 females(44.4%),with an average age of(21.6±10.4)years.All stents were successfully implanted,and the bilateral brachial-ankle blood pressure difference was significantly reduced compared with preoperation(P<0.05).The consistency test results of CFD simulation manometry and catheter manometry showed good results(mean difference 17.2mmHg,95%CI:1.81-36.24).Pearson correlation analysis showed that CFD preoperative and postoperative manometry was well correlated with catheter measurement results(preoperative r=0.74,P=0.02;postoperative r=0.95,P=0.01).This model can visualize and quantitatively demonstrate the changes of the active vascular dynamic environment in CoA patients before and after surgery.Conclusions:Based on CTA and non-invasive limb blood pressure and ultrasound Doppler data,CFD simulation technology can accurately predict the pressure gradients before and after surgery,and provide quantitative hydrodynamics data.This non-invasive measurement method can provide a good theoretical tool for clinicians to make surgical plans and virtual treatment.