A Systematic Review of Radiological Diagnosis and Management of May-Thurner Syndrome.

May-Thurner syndrome (MTS) is an anatomical condition of external luminal compression of common iliac vein due to a partial obstruction of the common iliac vein between common iliac artery and lumbar vertebra causes deep-vein thrombosis, venous hypertension, and chronic venous insufficiencies. In this article, we review present evidence of the clinical diagnosis and management of MTS. Here, we conducted a literature review of studies on MTS. We also reviewed different clinical features, presentation, diagnostic methods, and therapeutic procedure for this condition. Most studies mentioned the diagnosis of this condition is performed by color Doppler, computed tomographic angiography, venography, and problem-solving cases by intravascular ultrasound technique. Nonsurgical methods of management are first line, and vascular surgery is reserved for refractory cases. Multiple modalities are required to reach the diagnosis of MTS, and noninvasive intervention radiology methods are the first line of management. This review highlights the presentations of MTS and outlines diagnostic procedure and management.

Fibulin-1 promotes intimal hyperplasia after venous stent implantation through ACE mediated angiotensin II signaling.

Objective: Stent intimal hyperplasia leads to in stent restenosis and thrombosis. This study determined whether Fibulin-1 activity in smooth muscle cells (SMCs) contributes to stent restenosis or thrombosis. Methods: Stent implantation was conducted in a pig model. Target vessel samples were stained and analyzed by protein mass spectrometry. Cell experiments and Fibulin-1 SMC specific knockout mice (Fbln1SMKO) were used to investigate the mechanism of Fibulin-1 induced SMC proliferation and thrombosis. Results: SMC proliferation and phenotypic transition are the main pathological changes of intimal hyperplasia in venous stents. Protein mass spectrometry analysis revealed a total of 67 upregulated proteins and 39 downregulated proteins in intimal hyperplasia after stent implantation compared with normal iliac vein tissues. Among them, Fibulin-1 ranked among the top proteins altered. Fibulin-1 overexpressing human SMCs (Fibulin-1-hSMCs) showed increased migration and phenotypic switching from contractile to secretory type and Fibulin-1 inhibition decreased the activity of SMCs. Mechanistically, Fibulin-1-hSMCs displayed increased levels of angiotensin converting enzyme (ACE) expression and angiotensin II signaling. Inhibition of ACE or angiotensin II signaling alleviated the migration of Fibulin-1-hSMCs. Using Fibulin-1 SMC specific knockout mice (Fbln1SMKO) and venous thrombosis model, we demonstrated that Fibulin-1 deletion attenuated intimal SMCs proliferation and thrombosis. Further, Fibulin-1 concentration was high in iliac vein compression syndrome (IVCS) patients treated with stent and was an independent predictor of venous insufficiency. Conclusions: Fibulin-1 promotes SMC proliferation partially through ACE secretion and angiotensin II signaling after stent implantation. Fibulin-1 plays a role in venous insufficiency syndrome, implicating the protein in the detection and treatment of IVCS.

Challenging anticoagulation therapy for multiple primary malignant tumors combined with thrombosis: A case report and review of literature.

BACKGROUND: Venous thromboembolism significantly contributes to patient deterioration and mortality. Management of its etiology and anticoagulation treatment is intricate, necessitating a comprehensive consideration of various factors, including the bleeding risk, dosage, specific anticoagulant medications, and duration of therapy. Herein, a case of lower extremity thrombosis with multiple primary malignant tumors and high risk of bleeding was reviewed to summarize the shortcomings of treatment and prudent anticoagulation experience. CASE SUMMARY: An 83-year-old female patient was admitted to the hospital due to a 2-wk history of left lower extremity edema that had worsened over 2 d. Considering her medical history and relevant post-admission investigations, it was determined that the development of left lower extremity venous thrombosis and pulmonary embolism in this case could be attributed to a combination of factors, including multiple primary malignant tumors, iliac venous compression syndrome, previous novel coronavirus infection, and inadequate treatment for prior thrombotic events. However, the selection of appropriate anticoagulant medications, determination of optimal drug dosages, and establishment of an appropriate duration of anticoagulation therapy were important because of concurrent thrombocytopenia, decreased quantitative fibrinogen levels, and renal insufficiency. CONCLUSION: Anticoagulant prophylaxis should be promptly initiated in cases of high-risk thrombosis. Individualized anticoagulation therapy is required for complex thrombosis.

A comparative study of altered hemodynamics in iliac vein compression syndrome.

Introduction: Iliac vein compression syndrome (IVCS) is present in over 20% of the population and is associated with left leg pain, swelling, and thrombosis. IVCS symptoms are thought to be induced by altered pelvic hemodynamics, however, there currently exists a knowledge gap on the hemodynamic differences between IVCS and healthy patients. To elucidate those differences, we carried out a patient-specific, computational modeling comparative study. Methods: Computed tomography and ultrasound velocity and area data were used to build and validate computational models for a cohort of IVCS (N = 4, Subject group) and control (N = 4, Control group) patients. Flow, cross-sectional area, and shear rate were compared between the right common iliac vein (RCIV) and left common iliac vein (LCIV) for each group and between the Subject and Control groups for the same vessel. Results: For the IVCS patients, LCIV mean shear rate was higher than RCIV mean shear rate (550 ± 103 s-1 vs. 113 ± 48 s-1, p = 0.0009). Furthermore, LCIV mean shear rate was higher in the Subject group than in the Control group (550 ± 103 s-1 vs. 75 ± 37 s-1, p = 0.0001). Lastly, the LCIV/RCIV shear rate ratio was 4.6 times greater in the Subject group than in the Control group (6.56 ± 0.9 vs. 1.43 ± 0.6, p = 0.00008). Discussion: Our analyses revealed that IVCS patients have elevated shear rates which may explain a higher thrombosis risk and suggest that their thrombus initiation process may share aspects of arterial thrombosis. We have identified hemodynamic metrics that revealed profound differences between IVCS patients and Controls, and between RCIV and LCIV in the IVCS patients. Based on these metrics, we propose that non-invasive measurement of shear rate may aid with stratification of patients with moderate compression in which treatment is highly variable. More investigation is needed to assess the prognostic value of shear rate and shear rate ratio as clinical metrics and to understand the mechanisms of thrombus formation in IVCS patients.

A cadaver study evaluating intraluminal anomalies of the left common iliac vein.

OBJECTIVE: Intraluminal anomalies within the left common iliac vein, characteristic of iliac vein compression syndrome, are thought to result from compression by and pulsation of the overlying right common iliac artery. This cadaver study was designed to expand on the existing literature by surveying and photographing these spurs in addition to exploring whether certain factors, inherent to the cadaver, are associated with spur presence. METHODS: Dissection to expose the aorta, inferior vena cava, and common iliac arteries and veins was performed in 51 cadavers. The spinal level at which the iliac vein confluence occurred was noted. The point at which the right common iliac artery crossed the left common iliac vein was examined for plaque presence. The overlying arterial structures were then transected to expose the venous system. The inferior vena cava was incised to facilitate observation into the mouth and full extent of the left common iliac vein. Spurs were photographed and documented. Statistical analysis was conducted to determine whether sex, body mass index (BMI), plaque presence, or level of the iliac vein confluence are associated with spur presence. RESULTS: Spurs within the left common iliac vein were observed in 16 of 51 cadavers (31.4%). All spurs were located at the point that the right common iliac artery crossed the left common iliac vein. Using1 the classification system established by McMurrich, 67% of spurs (n = 10) were marginal and triangular; 25% (n = 4) were columnar. One marginal, linear spur (6%) and one partially obstructed spur with multiple synechiae (6%) were observed. Among this population, males were 73% less likely to have a spur (odds ratio, 0.269; P = .041). No significant relationship was found between plaque presence and spur presence (odds ratio, 0.933; P = .824) and no significant differences were noted between BMI and spur presence (χ2 = 1.752, P = .625). Last, a significantly greater percent of spurs was found within cadavers with an iliac vein confluence located at the L5/S1 disc space (χ2 = 9.650; P = .002). CONCLUSIONS: Study findings show that spurs are more common when the confluence of the common iliac veins occurs at a lower spinal level. The level of the iliac vein confluence may be important in identifying patients at increased risk of venous disease. The findings also suggest that plaque within the right common iliac artery and BMI display no distinct relationship with spur presence. Further investigation is needed to understand exactly what factors lead to spur formation.

Right-sided iliac vein compression syndrome: when the vein is compressed between the internal and external iliac arteries-a case report.

Background: In its normal anatomical relationship, the inferior vena cava is located on the right side of the abdominal aorta. Iliac vein compression syndrome (IVCS) is a pathological condition in which a blood clot is formed due to blood flow obstruction when the left common iliac vein is compressed between the right common iliac artery and the vertebral body. Therefore, right-sided IVCS (RIVCS) is rare. The effectiveness of treatment for RIVCS has not been sufficiently investigated. Case summary: A 51-year-old man developed deep vein thrombosis in the right lower extremity and non-massive pulmonary embolism during steroid treatment for IgA nephropathy. Magnetic resonance angiography (MRA) suggested iliac compression syndrome. Symptoms improved with the use of direct oral anticoagulants and compression stockings. At the 8-month follow-up, the clinical course was uneventful. Discussion: The causes of RIVCS in this case are believed to be the effects of steroids, prolonged sitting, and compression of the right external iliac vein. However, considering that deep vein thrombosis did not form in the left lower limb where there was no venous compression, it can be considered that the compression of the right external iliac vein had a significant impact. This case has been followed up for 8 months with anticoagulants and is progressing well. This is the first case to report the course of RIVCS treated conservatively with anticoagulant therapy for 8 months. This case suggested that conservative treatment is effective for RIVCS.

Clinical Outcomes at 3 Years After Stenting for Thrombotic and Non-thrombotic Iliac Vein Compression Syndrome Patients.

Iliac vein stenting for the treatment of iliac vein compression syndrome (IVCS) has been gradually developed. This article investigated the long-term patency and improvement of clinical symptoms after endovascular stenting for iliac vein obstruction patients. From 2020 to 2022, 83 patients at a single institution with IVCS underwent venous stent implantation and were divided into two groups: non-thrombotic IVCS (n = 55) and thrombotic IVCS (n = 28). The main stent-related outcomes include technical success, long-term patency, and thrombotic events. The technical success rate of all stent implantation was 100%. The mean length of hospital stay and cost were higher in the thrombotic IVCS group than in the non-thrombotic ICVS group, as well as the length of diseased vessel segment and the number of stents implanted were higher than in the control non-thrombotic group. The 1-, 2-, and 3-year patency rates were 85.4%, 80% and 66.7% in the thrombosis group, which were lower than 93.6%, 88.7%, and 87.5% in the control group (P = .0135, hazard ratio = 2.644). In addition, patients in both groups had a foreign body sensation after stent implantation, which resolved spontaneously within 1 year after surgery. Overall, there were statistically significant differences in long-term patency rate outcome between patients with thrombotic and non-thrombotic IVCS, the 1-, 2-, and 3-year patency rates in non-thrombotic IVCS patients were higher than those in thrombotic IVCS patients.

Quantitative Flow Measurements of Pelvic Venous Vasculature Using 4D Flow MRI.

RATIONALE AND OBJECTIVES: To evaluate 4D Flow magnetic resonance imaging (MRI) sequences for quantitative flow measurements of the pelvic venous vasculature. MATERIALS AND METHODS: A prospective study of healthy volunteers was performed. After informed consent all subjects underwent 4D flow sequences at a 3 T MRI scanner with different isotropic resolution and different velocity encoding (Venc) settings: (sequence #1) voxel size (VS) 1.63 mm3, Venc 50 cm/s; (sequence #2) VS 1.63 mm3, Venc 100 cm/s and (sequence #3) VS 2.03 mm3, Venc 50 cm/s. Perfusion parameters were calculated for all venous vessel segments starting at the level of the inferior vena cava and extending caudally to the level of the common femoral vein. For reference, arterial flow was calculated using 1.63 mm3 isotropic resolution with a Venc of 100 cm/s. RESULTS: Ten healthy subjects (median age 28 years, interquartile range [IQR]: 26.25-28 years) were enrolled in this study. Median scanning time was 12:12 minutes (IQR 10:22-13:32 minutes) for sequence #1, 11:02 minutes (IQR 9:57-11:19 minutes) for sequence #2 and 6:10 minutes (IQR 5:44-6:47 minutes) for sequence #3. Flow measurements were derived from all sequences. The venous pelvic vasculature showed similar perfusion parameters compared to its arterial counterpart, for example the right common iliac arterial segment showed a perfusion of 8.32 ml/s (IQR: 6.94-10.68 ml/s) versus 7.29 ml/s (IQR: 4.70-8.90 ml/s) in the corresponding venous segment (P = 0.218). The venous flow measurements obtained from the three investigated sequences did not reveal significant differences. CONCLUSION: 4D Flow MRI is suitable for quantitative flow measurement of the venous pelvic vasculature. To reduce the scanning time without compromising quantitative results, the resolution can be decreased while increasing the Venc. This technique may be utilized in the future for the diagnosis and treatment response assessment of iliac vein compression syndromes.

Effectiveness of iliac vein stenting combined with endovenous laser treatment of recurrent varicose veins associated with iliac vein compression.

Background: Iliac vein compression syndrome (IVCS) is an underlying cause of varicose vein (VV) recurrence after venous surgery. However, the management of recurrent varicose veins (RVVs) combined with IVCS has rarely been reported. This study aimed to investigate the outcomes of a one-stop procedure to correct outflow obstruction and superficial reflux for patients with RVVs and IVCS. Methods: A retrospective analysis was conducted of 102 consecutive patients diagnosed with RVVs. Computed tomography venography (CTV) was performed to confirm IVCS. The cases were divided into 2 groups: the IRVVs group, including patients with RVVs and IVCS (n=48), and the RVVs group, including patients with RVVs only (n=54). The characteristics, vein reflux, and clinical, etiological, anatomical, and pathophysiological (CEAP) distribution were investigated. Then, the IRVVs group patients who underwent endovenous laser ablation (EVLA) (n=39) were divided into a further 2 groups: the EVLA + S group (n=19), who received EVLA and stenting of iliac vein, and the EVLA group (n=20), who received EVLA treatment alone. The great/small saphenous vein (GSV/SSV) trunk occlusion, VV recurrence, visual analogue scale (VAS), and venous clinical severity score (VCSS) were investigated. Results: The prevalence rate of femoral vein reflux was 81.2% in IRVVs group and 50% in RVVs group (P<0.05). In the IRVVs group, 72.9% of patients manifested as CEAP clinical class >3, which was higher than that in RVVs group (48.1%) (P<0.05). The 12-month GSV/SSV occlusion rate in the EVLA + S and EVLA groups were 94.7% and 90.0%, respectively. Totals of 9 patients in EVLA + S group and 6 patients in EVLA group had active venous ulcers, and the ulcer healing time in EVLA + S group was significantly shorter (27.22±7.12 vs. 46.67±9.83 days, P<0.05). The reductions in the VAS and VCSS values between baseline, 1 month, and 12 months in the EVLA + S group were more obvious than those in EVLA group (P<0.05). Conclusions: The one-stop combination treatment of iliac venous stenting and EVLA in patients with RVVs and IVCS is safe and effective and provides prominent symptom relief, improved quality of life, and a more satisfactory ulcer healing than EVLA alone.

Efficacy of modified time of flight magnetic resonance venography in diagnosis of iliac vein compression syndrome.

OBJECTIVE: We investigated the diagnostic efficacy of modified time of flight magnetic resonance venography (mTOF-MRV) for iliac vein compression syndrome diagnosis by optimizing the scanning parameters and improving image quality. METHODS: A retrospective study was conducted on 69 patients who underwent routine time of flight magnetic resonance venography (TOF-MRV) and 85 patients who received mTOF-MRV. Assessment of image quality of the two methods was performed by two radiologists using a four-point method. The sensitivity, specificity, positive and negative predictive values of TOF-MRV and mTOF-MRV in the diagnosis of significant iliac vein compression (stenosis >50%) were analyzed by calculating the iliac vein stenosis rates of the two methods and using digital subtraction angiography (DSA) as the gold standard. RESULTS: Inter-observer assessment of objective data measurement revealed excellent agreement {ICC [95% confidence interval (CI)]: 0.972 (0.953 to 0.983) for TOF-MRV and 0.979 (0.965 to 0.988) for m-TOF MRV, 0.976 (0.960 to 0.986) for DSA}. The mean error of stenosis rate of mTOF-MRV was markedly smaller than that of TOF-MRV (p < 0.05). Sensitivity, specificity, positive and negative predictive values of TOF-MRV in the diagnosis of significant stenosis were 100%, 95%, 67% and 100%, respectively. The sensitivity, specificity, positive and negative predictive values of mTOF-MRV were 100%. The mean image score for the mTOF-MRV was 3.63 ± 0.59, which was significantly higher compared with that of TOF-MRV (2.19 ± 0.42). CONCLUSION: mTOF-MRV has better image quality and can accurately diagnose venous stenosis. Therefore, it can be used for the detection of iliac vein compression syndrome and further assessment after endovascular interventions.

An ultrasound imaging and computational fluid dynamics protocol to assess hemodynamics in iliac vein compression syndrome.

OBJECTIVE: Elevated shear rates are known to play a role in arterial thrombosis; however, shear rates have not been thoroughly investigated in patients with iliac vein compression syndrome (IVCS) owing to imaging limitations and assumptions on the low shear nature of venous flows. This study was undertaken to develop a standardized protocol that quantifies IVCS shear rates and can aid in the diagnosis and treatment of patients with moderate yet symptomatic compression. METHODS: Study patients with and without IVCS had their iliac vein hemodynamics measured via duplex ultrasound (US) at two of the following three vessel locations: infrarenal inferior vena cava (IVC), right common iliac vein, and left common iliac vein, in addition to acquiring data at the right and left external iliac veins. US velocity spectra were multiplied by a weighted cross-sectional area calculated from US and computed tomography (CT) data to create flow waveforms. Flow waveforms were then scaled to enforce conservation of flow across the IVC and common iliac veins. A three-dimensional (3D), patient-specific model of the iliac vein anatomy was constructed from CT and US examination. Flow waveforms and the 3D model were used as a basis to run a computational fluid dynamics (CFD) simulation. Owing to collateral vessel flow and discrepancies between CT and US area measurements, flows in internal iliac veins and cross-sectional areas of the common iliac veins were calibrated iteratively against target common iliac flow. Simulation results on mean velocity were validated against US data at measurement locations. Simulation results were postprocessed to derive spatial and temporal values of quantities such as velocity and shear rate. RESULTS: Using our modeling protocol, we were able to build CFD models of the iliac veins that matched common iliac flow splits within 2% and measured US velocities within 10%. Proof-of-concept analyses (1 subject, 1 control) have revealed that patients with IVCS may experience elevated shear rates in the compressed left common iliac vein, more typical of the arterial rather than the venous circulation. These results encourage us to extend this protocol to a larger group of patients with IVCS and controls. CONCLUSIONS: We developed a protocol that obtains hemodynamic measurements of the IVC and iliac veins from US, creates patient-specific 3D reconstructions of the venous anatomy using CT and US examinations, and computes shear rates using calibrated CFD methods. Proof-of-concept results have indicated that patients with IVCS may experience elevated shear rates in the compressed left common iliac vein. Larger cohorts are needed to assess the relationship between venous compression and shear rates in patients with IVCS as compared with controls with noncompressed iliac veins. Further studies using this protocol may also give promising insights into whether or not to treat patients with moderate, yet symptomatic compression.

Iliac vein compression syndrome by lumbar degenerative changes is associated with deep vein thrombosis after total knee arthroplasty.

INTRODUCTION: This study aimed to identify whether iliac vein compression syndrome(IVCS) is associated with deep vein thrombosis(DVT) after total knee arthroplasty(TKA) and whether lower lumbar degenerative changes were risk factors for IVCS. MATERIALS AND METHODS: A total of 259 consecutive patients who underwent TKA from January 2019 to March 2022 was retrospectively reviewed. Preoperative plain radiographs of lumbar spines and CT venography (CTV) for DVT diagnosis at postoperative 7 days were performed in all patients. Imaging findings of lower lumbar degenerative changes were analyzed on plain radiograph including lateral osteophytes, scoliosis, lateralolisthesis, retrolisthesis, anterolisthesis, and lower lumbar lordosis angle (LLLA). Percent compression at the left common iliac vein (LCIV) and right common iliac vein (RCIV) as well as DVT were evaluated on CTV. Moreover, IVCS was defined as greater than 50% of compression of the iliac vein on CTV. RESULTS: DVT occurred in 79 patients (30.5%) after TKA. The overall occurrence of DVT was significantly higher in patients with IVCS of LCIV (52.8%) than those without (18.8%, P < 0.001). When DVT was further subdivided, compared to non-IVCS, IVCS of LCIV was significantly associated with bilateral DVT (P < 0.001, both), especially distal DVT (P < 0.001, both), and IVCS of RCIV was significantly associated with right-side DVT (P = 0.031), especially popliteal (P = 0.008) and distal DVT(P = 0.011). Female patients (OR: 3.945, P = 0.039), presence of left osteophyte (OR: 2.348, P = 0.006), and higher LLLA (OR: 1.082, P < 0.001) were significantly associated with IVCS of LCIV, and presence of right osteophyte (OR: 3.494, P = 0.017) was significantly associated with IVCS of RCIV. CONCLUSION: IVCS was significantly associated with DVT after TKA and lumbar degenerative changes with lateral osteophytes and hyperlordosis were significant risk factors for IVCS.

Intravascular Ultrasound in Treating Iliac Vein Compression With Endovascular Stenting: A Necessary Tool for Optimal Outcomes.

Symptomatic compression of the left common iliac vein between the right common iliac artery and spinal vertebrae is referred to as May-Thurner Syndrome (MTS). Atypical cases of MTS including compression of the left external iliac vein, right iliac vein or the inferior vena cava can also coexist and cause double vein compression. Current literature suggests that endovascular treatment including thrombolysis, thrombectomy, venoplasty and stent placement to correct the mechanical obstruction together with anticoagulation therapy is safe and a reasonable management for patients with MTS. Intravascular ultrasound (IVUS) can aid in the diagnosis and the operative planning of MTS, especially regarding sizing and precise deployment of venous stents. Here we present 2 unique atypical cases of MTS with double left iliac vein compression treated endovascularly with stent placement along the common and external iliac vein with the assistance of IVUS.

Fully protruding into the inferior vena cava deployment of braided stent in the treatment of iliac compression syndrome / 中华普通外科杂志

Objective:To evaluate the clinical efficacy of metal braided stent deployed by fully protruding into the inferior vena cava for the treatment of iliac vein compression syndrome(IVCS).Methods:The clinical data of patients with IVCS treated with interwoven nitinol mesh stent protruding into the inferior vena cava and released from Jan 2018 to May 2021 in our center were retrospectively analyzed.Results:A total of 118 patients were included in this study. Among them, 7 cases were complicated with acute thrombosis, 3 cases were complicated with post thrombotic syndrome (PTS), and 108 cases were no more thrombotic iliac vein compression. The technical success rate was 100%, with an average of 2.03±0.77 stents implanted. Of the 23 ulcer patients, 18 ulcers healed after intervention, and the healing rate was 78.26%. The postoperative CEAP grade was significantly improved ( t=11.54, P<0.01), and the primary patency rate and second patency rate were 97.46% and 98.31% at 1 year after intervention. Conclusion:The fashion of fully protruding into inferior vena cava deployment in the treatment of iliac vein compressive disease has a high patency rate and satisfactory clinical efficacy.

Effects of Human Postures on Flow Characteristics in Iliac Vein Compression Syndrome / 医用生物力学

Objective To investigate effects of human postures on flow characteristics of iliac vein compression syndrome. Methods The numerical model of iliac vein was reconstructed from CT images of a typical patient with pelvic-type iliac vein compression syndrome with collateral veins. Based on the computational fluid dynamics method, the non-Newtonian model and the porous media model were adopted to describe effects of abnormal structures on blood flow and acquire the wall shear stress and pressure of iliac vein. The discrete phase model was used to study the residence conditions of erythrocytes under three human postures. Results The pressure gradient at two ends of the compressive region was lowest under lying state, while the iliac vein showed a high pressure under sitting and walking states. The local maximum wall shear stresses under three postures were found at narrow segment of the collateral vein and convergence region of two flows of right iliac vein. The maximum shear stress was largest under lying state and smallest under sitting state. The blood residence time of 52.2 s in the left iliac vein was the longest under sitting state. The residence time of 14.8 s was shortest under lying state. The blood residence time was 23.8 s under walking state. Conclusions Porous media model used to simulate the effect of abnormal structures was highly consistent with the angiography data. The venous hypertension under sitting and walking states was consistent with the clinical results, and the lying state could relieve the hypertensive condition. In terms of wall shear stress and blood residence time in iliac vein, the continual change between three human postures would cause endothelial damage and blood flow stasis alternately, thus increase the risk of thrombosis.

Ultrasound characteristics of abdominal vascular compression syndromes.

Abdominal vascular compression syndrome (AVCS) is caused by the compression of abdominal blood vessels by adjacent structures or the compression of abdominal organs by neighboring blood vessels. Such compressions can result in a variety of clinical symptoms. They are not commonly seen in ultrasound practices, and their presence may have been underrecognized and underdiagnosed. This article reviews the clinical features, ultrasound characteristics, and diagnostic criteria of four types of AVCS, namely, celiac artery compression syndrome, renal vein compression syndrome, iliac vein compression syndrome, and superior mesenteric artery syndrome to increase awareness of these conditions among ultrasound practitioners. The ultrasound criteria for AVCS are primarily based on studies with small sample sizes, and therefore, it is important to exercise caution if these criteria are used.

Morphometric and Hemodynamic Analysis of the Compressed Iliac Vein.

PURPOSE: To investigate the relationship between the morphological structure and hemodynamic properties of the compressed iliac vein and explore the reason for the formation of thrombosis in the compressed iliac vein. MATERIALS AND METHODS: A total of 11 patients with iliac vein compression syndrome (IVCS) were included in this study, and their iliac veins were reconstructed in 3 dimensions (3D). The morphological structures of the iliac veins (confluence angle, degree of stenosis) were analyzed based on the 3D model. Variations in the hemodynamic properties of the iliac vein were investigated at 4 typical moments in one cardiac cycle, and the relationship between the different morphological configurations and the pressure difference was investigated. RESULTS: In the region of the compressed iliac vein, the blood flow velocity is accelerated and the pressure changes abruptly accompanied by the increase in pressure difference. Higher time averaged wall shear stress (TAWSS) and lower relative residence time (RRT) appeared in stenosis regions of compressed iliac vein, while TAWSS was low and RRT was large near the stenosis position. There was a strong positive correlation between the degree of stenosis and the pressure difference (r=0.894), and a positive correlation between the confluence angle of the iliac vein and the pressure difference (r=0.638). CONCLUSION: The morphological structure of the compressed iliac vein has an obvious influence on the hemodynamic surroundings; the pressure difference becomes larger when the degree of stenosis and the confluence angle increase. The iliac vein luminal areas with low TAWSS and high RRT near the compressed location can impede blood flow and lead to accumulation of blood components, which may increase the risk of thrombosis formation and should be fully considered in the treatment of IVCS.

Seizures, deep vein thrombosis, and pulmonary emboli in a severe case of May-Thurner syndrome: a case report.

BACKGROUND: May-Thurner syndrome is a vascular disorder caused by the right common iliac artery compressing the left common iliac vein against the lumbar spine, causing distal venous stasis and potentially leading to fibrous change in the venous wall structure. Although May-Thurner syndrome is most commonly discovered in females upon investigation of new-onset deep vein thrombosis, we present the case of an otherwise healthy 29-year-old male with severe May-Thurner syndrome who presented with seizures, bilateral deep vein thrombosis, and diffuse pulmonary emboli. Seizures constituted the earliest presenting symptoms for the patient. Although it is difficult to prove that the patient's seizures were related to the May-Thurner syndrome, this possible association renders this case extraordinary. CASE PRESENTATION: This report describes the case of a 29-year-old previously healthy white male with a severe case of left-sided May-Thurner syndrome that required extensive medical and interventional treatment. The patient experienced two seizures, one month apart, both of which occurred while residing at high altitude. The patient had no prior history of seizures, and epilepsy was ruled out. Three weeks after the second seizure, he presented to the emergency room with hemoptysis, dyspnea, and severe leg pain. Sites of thrombus were confirmed in both legs and diffusely in the lungs. Etiological work-up after treatment with intravenous tissue plasminogen activator revealed May-Thurner syndrome. Hematology workup including genetic testing showed no evidence of coagulopathy. Bilateral common iliac venous stents were placed to attempt definitive treatment. Despite stenting, the patient had another thrombotic event with associated sequelae after discontinuation of anticoagulation. The patient has not had another seizure since the stents were placed. Despite the negative testing, the patient remains on lifelong chemoprophylaxis in the event of an undiscovered hypercoagulopathy. CONCLUSIONS: The care team theorizes that the seizures resulted from hypoxia due to May-Thurner syndrome-induced hemostasis and associated thrombotic events, the high-altitude location of his residence at the time he experienced the seizures, and shallow breathing during sleep. For patients with lower limb venous thrombosis, May-Thurner syndrome should be considered in the differential diagnosis. Endovascular treatment followed by extended prophylactic anticoagulation therapy until the patient is determined to be no longer at risk for thrombosis is recommended. Post-venoplasty thrombosis is a common complication of endovascular treatment of May-Thurner syndrome and should be carefully monitored.

Efficacy of one-stop endovascular intervention in treatment of left iliac vein compression syndrome complicated with deep venous thrombosis of lower limbs.

OBJECTIVE: To evaluate the clinical effect and safety of one-stop endovascular intervention in treatment of left iliac vein compression syndrome (IVCS) complicated with deep venous thrombosis (DVT) of lower limbs. METHODS: Clinical data of 26 patients with secondary DVT due to IVCS admitted in the Department of Vascular Surgery, Hebei General Hospital from January 2018 to December 2021 were retrospectively analyzed. All patients underwent one-stop endovascular intervention procedure, including ultrasound-guided deep venipuncture, Angiojet catheter aspiration, iliac vein balloon dilation, stent implantation and simultaneous filter retrieval. The operation time and catheter aspiration time were documented; the preoperative and postoperative left lower extremity deep vein venous patency, circumferences of bilateral limbs at 15 cm above the knee and 10 cm below the knee, and the levels of hemoglobin, creatinine, alanine aminotransferase (ALT), aspertate aminotransferase (AST), total bilirubin and indirect bilirubin were measured. The incidence of post-thrombotic syndrome (PTS) and iliac vein stent patency were recorded through follow-up. RESULTS: The one-stop endovascular intervention was successfully performed in 26 patients, with the operation time of (171±35) min and the thrombolysis time of (263±89) s. After treatment, the left lower extremity deep vein venous patency, circumferences of bilateral limbs at 15 cm above the knee and 10 cm below the knee were decreased (all P<0.01); the hemoglobin level were decreased, the creatinine, ALT, AST, total bilirubin and indirect bilirubin levels were increased (all P<0.01). Patients were followed up for 1-12 months. Stent thrombosis occurred in 1 patient 7 months after procedure, and the symptoms were improved after conservative treatment; the stents were unobstructed in all patients, 1 patient had stent mural thrombosis, in whom the stent blood flow was not affected. No PTS was observed during the follow-up. CONCLUSIONS: The one-stop endovascular interventional treatment of IVCS complicated with DVT of left lower limb is safe and effective. Attention should be paid to the changes of liver and kidney function caused by catheter aspiration during the treatment, and corresponding intervention should be given in time to avoid the occurrence of related complications.