Relationship Between Dual Left Iliac Vein Compression And Deep Venous Thrombosis Of Left Lower Extremity

Objective:To observe the anatomy of dual left iliac vein compression by abdominal contrast-enhanced CT with multi-dimensional imaging.And to study the relationship between dual left iliac vein compression and left sided deep vein thrombosis(DVT)by the clinical and imaging data,So as to provide some scientific basis for the prevention and treatment of DVT to this kind of populationMethods:Eighty-nine patients with left lower extremity DVT who were treated in our hospital from October 2016 to October 2018,aged?18 years,were diagnosed as acute or subacute DVT,but not peripheral DVT.They had no history of DVT in the left lower extremity,no history of endovascular surgery of the lower extremity vessels,no history of iodine contrast allergy,no abnormal arterial or tumor compress on the left iliac vein,and the iliac vein in a clear visualization.After admission,an abdominal CT scan was performed immediately to determine whether there was an abdominal tumor or abnormal tissue directly compressing the iliac vein,and to find the degree of compression of the iliac vein.At the same time,a total of 210 patients with non-lower extremity vascular disease(age ? 18 years old.no history of venous disease of lower extremity)were enrolled in our hospital for abdominal CT examination.Collect the patient's gender,age,range of thrombus distribution,onset time of DVT.The range of thrombus distribution is mainly divided into iliac DVT(involving iliac vein),non-iliac DVT(not involving iliac vein),isolated iliac DVT(only involving iliac vein).The onset time is from the onset of symptoms to the time when the symptoms are significantly aggravated.For each patient,the minor diameter of the LCIV was measured at the site of maximal compression of LCIV where the RCIA or LCIA crossing on CT cross-sectional images.Meanwhile,the diameter of the RCIV was measured at the same level.The degree of LCIV compression we calculated it as follow.((RCIV diameter-LCIV minor diameter)/RCIV diameter)x 100%.The left iliac-vena cava angle(LIVCA)was measured at the junction of LCIV midline and inferior vena cava midline on two-dimensional reconstruction images.Three-dimensional reconstruction of all tomographic images was performed,and the positional relationship between the compressed left iliac vein and the radial artery and the spine was located through the workstation system.Patients with dual LCIV compression confirmed by CT tomography were used as the control group,and patients with single-type compression were used as the control group,the working characteristic(ROC)curve of the different LIVCA was drawn,and the area under the curve and the 95%confidence interval were calculated,The influences of single and dual compression on the risk of left-sided DVT formation were investigated using logistic regression analysisResults:In DVT patients with dual left iliac vein compression,the prevalence of iliac DVT was significantly higher(85%vs 55%,P<0.01),the onset time of acute iliac DVT was significantly shorter[(2.46±1.39)d vs(3.78±1.81)d,P<0.05],the incidence of isolated DVT was significantly higher(15%vs 2%,P<0.05),compared with sole compression DVT patients,the LIVCA is significantly smaller[(126.0±8.05)°vs(138.12±5.13)°,P<0.01].and the degree of LCIV compression was significantly,higher[(77±8)%vs(56± 18)%,P<0.01].In all patients of this study,the level of LCIV compression was greater than that in non-DVT group(P<0.01),but there was no significant difference in LIVCA and RCIV diameter between the same compression type of DVT and non-DVT patients(P>0.05).The area under the ROC curve for LIVCA diagnosis of double left iliac vein compression was 0.916(95%Cl 0.87?0.96,P<0.01),the cut-off value was 130.4°.Patients with left lower extremity DVT were divided into three categories according to the degree of stenosis of LCIV:<50%,50%-70%.>70%.In sole compression patients,it was an important risk factor for DVT formation,when the LCIV compression was>70%(OR=5.19,95%C14.32-37.12,P<0.01),while in dual compression patients,it was?50%(OR=3.01,95%CI1.23?9.96.P<0.05).Conclusion:The small LIVCA is the main factor for the formation of dual LCIV compression,which is more likely to be secondary to DVT than single-type compression,and it is one of the important causes of iliac DVT.