Left Common Iliac Vein Compression With Secondary Deep Venous Thrombosis:Relevant Imaging Anatomy,Risk Prediction Model And No-filter Endovascular Treatment Protocol

The anatomical basis of the left common iliac vein(LCIV)compression lies in the chronic pulsations of the overlying right common iliac artery and the anterior protrusion of lumbosacral vertebrae.Compression of LCIV leads to hypertension in veins and causes relevant symptoms.The compression percentage(CP)of LCIV,distribution of compression severity(CS)and their affecting factors in various population remain to be unclear.In the first chapter,a multi-center cross-sectional study was conducted in Guangdong province and CT parameters in 1078 subjects were obtained.Statistical analysis demonstrated that the mean CP in the unselected population(US-P),no vascular-related symptom population(NVS-P)and deep venous thrombosis population(DVT-P)were 43.1%,43.0%and 77.1%,respectively.In US-P and NVS-P,there were 41.65%and 42.5%of subjects with CP from 25%to 50%,respectively,and there were 38.59%and 37.7%of subjects with CP greater than 50%.The CP in women was higher than that in men.The CP in the Young-Middle-age group was higher than that in the Old-age group.Middle-aged women accounted for the highest proportion in the subjects with CP greater than 50%.Age had significant impact on the CS in women.Gender,age,the diameter of right common iliac vein and the bifurcation angle of inferior vena cava had significant influence on the CS distribution.Gender,age and the diameter of right common iliac vein were associated CP.In the NVS-P and DVT-P,the range of CP were 0%-89.86%and 42.20%?95.20%,respectively.Overlap can been seen in these two population.The results indicated that LCIV compression and other risk factors worked together in leading to DVT.In the second chapter,a case-control study was conducted to the evaluate weighting of LCIV compression in leading to DVT based on thrombosis risk assessment model(RAM)and to establish DVT prediction model.Statistical analysis demonstrated the LCIV diameter,LCIV-CP and risk scores in the case group were significant higher than that in control group.The results had confinned the correlation-ship between LCIV compression and DVT of the left lower extremity.On multivariate analysis based on Caprini-RAM,and adjusting for risk factor scores,the odds of left-sided DVT increased by a factor of 2.36 for each 1-mm decrease in LCIV diameter and increased by a factor of 3.34 for each 10 percent increase in LCIV-CP.On multivariate analysis based on Padua-RAM,and adjusting for risk factor scores,the odds of left-sided DVT increased by a factor of 2.35 for each 1-mm decrease in LCIV diameter and increased by a factor of 3.50 for each 10 percent increase in LCIV-CP.On multivariate analysis based on Caprini-RAM or Padua-RAM,and adjusting for LCIV diameter,the odds of left-sided DVT increased by a factor of 1.56 or 1.98 for each score increase.At a specific LCIV-CP,the probability of left-sided DVT increased along with risk score,vice versa.The weighting coefficient of risk score calculated based on Caprini-RAM or Padua-RAM were 0.55 and 0.12,while that of LCIV-CP were 0.61 and 0.13.The probability of left-sided DVT could be predicted using the following models:PCaprini=[EXP(Logit P)/(1+EXP(Logit P),Logit P=-8.24+0.55·X1+0.12·X₂]and PPadua=[EXP(Logit P)/(1+EXP(Logit P),Logit P=-9.07+0.61·X1+0.13·X₂].ROC and Hosmer-Lemeshow test indicated that these two models showed good discrimination and calibration.Soft-ware"Predicting the probability of left-sided DVT V1.0" has been designed based on the above models.In the last chapter,a retrospective study was conducted to evaluate the safety and effectiveness of endovascular treatment protocol for acute proximal DVT secondary to LCIV compression without inferior vena cava filter(IVCF)placement.No symptomatic pulmonary embolism was observed in peri-intervention periods.The preliminary results suggested that PEVI without IVCF placement for DVT secondary to LCIV compression but without IVC thrombosis or symptomatic pulmonary embolism was safe and feasible.The technique success rate and clinical success rate were both 100%.The primary patency rates at 12 and 24 months were 93.8%and 91.4%,respectively,which remained stable at 36,48,and 60 months.The secondary patency rates at 12 and 24 months were 95.7%and 93.3%,respectively,and there were no changes at 36,48 and 60 months.Prospective and comparative studies with larger sample are warranted to evaluate the safety profile of no-filter endovascular protocol.