Iliac compression syndrome and recanalization of femoropopliteal and iliac venous thrombosis: a prospective study with magnetic resonance venography

Preprocedural imaging modalities in patients undergoing iliocaval venous recanalization and stent placement

PURPOSE

To determine the diagnostic accuracy of preinterventional imaging modalities in patients being evaluated for iliocaval venous recanalization and stent placement.

METHODS

Consecutive patients with iliocaval postthrombotic obstructions or nonthrombotic iliac vein lesions (NIVL), who were scheduled for recanalization, underwent duplex ultrasound (DUS), magnetic resonance venography (MRV), multiplanar venography (MPV), and intravascular ultrasound (IVUS). The diagnostic accuracies of DUS, MRV, and MPV were analyzed using IVUS as reference.

RESULTS

A total of 216 limbs in 108 patients (80 patients with postthrombotic obstructions, 28 patients with NIVL) were examined. In patients with postthrombotic obstructions, the diagnostic sensitivities for the detection of lesions of the common femoral vein were 81% (95% CI 71-89%) for DUS, 76% (95% CI 65-85%) for MRV, and 86% (95% CI 76-93%) for MPV. The sensitivities for detecting lesions of the iliac veins were 96% (95% CI 89-99%) for DUS, 99% (95% CI 92-100%) for MRV, and 100% (95% CI 94-100%) for MPV. Regarding the inferior vena cava, the sensitivities were 44% (95% CI 24-65%) for DUS, 52% (95% CI 31-73%) for MRV, and 70% (95% CI 47-86%) for MPV. The sensitivities for detecting NIVL were 58% (95% CI 34-79%) for DUS, 90% (95% CI 68-97%) for MRV, and 95% (95% CI 73-99%) for MPV.

CONCLUSION

In patients scheduled for recanalization of iliocaval postthrombotic obstructions, the sensitivities of DUS, MRV, and MPV were similar. In patients with suspected inferior vena cava involvement and in patients with NIVL, additional imaging with MR or conventional venography is required.

Combined high-resolution 3D CUBE T1-weighted imaging and non-contrast-enhanced magnetic resonance venography for evaluation of vein stenosis in May-Thurner syndrome

PURPOSE

To explore the feasibility of high-resolution MRI 3-dimensional (3D) CUBE T1-weighted magnetic resonance imaging (MRI) in combination with non-contrast-enhanced (NCE) magnetic resonance venography (MRV) for the assessment of lumen stenosis in May-Thurner syndrome.

METHODS

Twenty-nine patients underwent computed tomography venography (CTV) and high-resolution MRI-CUBE T1, and NCE MRV acquisitions. ANOVA and LSD tests were used to compare the stenosis rate and narrowest and distal diameters of the vessel lumen.

RESULTS

There were no significant differences in the estimated stenosis rate between CTV, CUBE T1, and NCE MRV (p = 0.768). However, there were significant differences in the measured stenosis diameters of the left common iliac vein (LCIV), with CTV giving the largest mean diameter and CUBE had the smallest mean diameter (p < 0.05). The measured normal LCIV diameters did not significantly differ between MRV and CUBE (p = 0.075) but were significantly larger on CTV than on MRV and CUBE (p < 0.05).

CONCLUSIONS

Compared with CTV, a combination of CUBE and MRV could provide an improved assessment of the degree of lumen stenosis in May-Thurner syndrome and demonstrate acute thrombosis. MRI underestimates the diameter of the vessel in comparison with CTV. MRI can be a substitute tool for Duplex ultrasound and CTV.

Artifact quantification of venous stents in the MRI environment: Differences between braided and laser-cut designs

PURPOSE

To quantify B₀- and B₁-induced imaging artifacts of braided venous stents and to compare the artifacts to a set of laser-cut stents used in venous interventions.

METHODS

Three prototypes of braided venous stents with different geometries were tested in vitro. B₀ field distortion maps were measured via the frequency shift Δf using multi-echo imaging. B₁ distortions were quantified using the double angle method. The relative amplitudes B₁^rel were calculated to compare the intraluminal alteration of B₁. Measurements were repeated with the stents in three different orientations: parallel, diagonal and orthogonal to B₀.

RESULTS

At 1.5 T, the braided stents induced a maximum frequency shift of Δfx<100Hz. Signal voids were limited to a distance of 2 mm to the stent walls at an echo time of 3 ms. No substantial difference in the B₀ field distortions was seen between laser-cut and braided venous stents. B₁^rel maps showed strongly varying distortion patterns in the braided stents with the mean intraluminal B₁^rel ranging from 63±18% in prototype 1 to 98±38% in prototype 2. Compared to laser-cut stents the braided stents showed a 5 to 9 times higher coefficient of variation of the intraluminal B₁^rel.

CONCLUSION

Braided venous stent prototypes allow for MR imaging of the intraluminal area without substantial signal voids due to B₀-induced artifacts. Whereas B₁ is attenuated homogeneously in laser-cut stents, the B₁ distortion in braided stents is more inhomogeneous and shows areas with enhanced amplitude. This could potentially be used in braided stent designs for intraluminal signal amplification.

Contemporary treatment of May-Thurner Syndrome

Compression of the left common iliac vein by the overlying right common iliac artery is a benign anatomic abnormality in most individuals. However, in patients with significant vein compression, outflow obstruction and chronic intraluminal venous damage may lead to May-Thurner Syndrome. This syndrome commonly manifests as unilateral left leg swelling or acute iliofemoral deep venous thrombosis. In addition to clinical findings, diagnosis is made with ultrasound, computed tomography venography, or magnetic resonance venography. The extent of compression of the iliac vein is best determined by venography with intravascular ultrasound. Symptoms and hemodynamic significance of the compression guides the ideal treatment approach. Iliocaval stenting has become the standard treatment for this condition and has promising patency rates and clinical outcomes. This review paper provides an overview of pathophysiology, and utility and limitations of the existing diagnostic modalities and treatment options in the management of May-Thurner Syndrome.

Early clinical outcomes for treatment of post-thrombotic syndrome and common iliac vein compression with a hybrid Oblique self-expanding nitinol stent – the TOPOS study

Summary: Background: Physical attributes of conventional stents used in the ilio-caval territory are often unfavorable in the presence of external compression close to the bifurcation. A hybrid oblique stent was developed for the treatment of common iliac vein compression without compromising the contralateral iliac vein inflow. Patients and methods: The ongoing international monitored TOPOS study enrolled 60 patients with post-thrombotic syndrome (PTS) treated with the sinus-Obliquus stent (optimed) and provisional distal stent extension. At 3-month follow-up, patency rates were obtained from duplex ultrasound, and clinical outcomes were assessed by the Villalta score, revised venous severity score (rVCSS), pain intensity score and chronic venous disease quality of life questionnaire (CIVIQ-20). Results: Mean age was 46.6 ± 14.9 years (68.3 % women). Mean number of implanted stents was 1.9 ± 0.6; 12 (20 %) patients received the hybrid oblique stent only. Forty-eight (80 %) patients had distal stent extension, and 42 (70 %) had stents below the inguinal ligament. Four (7 %) patients (all with stent extension) developed stent thrombosis. Primary and secondary patency rates at 3 months were 93.1 % (95 %CI 83.3–98.1 %), and 100 % (95 %CI 93.8–100 %), respectively. Improvement in Villalta, rVCSS, CIVIQ-20, and pain intensity score from baseline to 3-month follow-up was 6.9 ± 1.4 points (95 %CI 4.1–9.8; p < 0.0001), 3.4 ± 1.0 points (95 %CI 1.3–5.4 points; p < 0.01), 13.6 ± 2.7 points (95 %CI 8.2–19.0 points; p < 0.0001), and 2.4 ± 0.5 (95 %CI 1.4–3.3; p < 0.0001), respectively. At follow-up, 38 (63 %) patients were free from the PTS and none developed contralateral deep vein thrombosis. Conclusions: In patients with PTS and common iliac vein compression, treatment with the hybrid oblique stent with provisional stent extension resulted in high patency rates and improvement in PTS severity and quality of life at 3-month. Two-year results of TOPOS will assess the durability of this treatment.

Review of imaging and endovascular intervention of iliocaval venous compression syndrome

Iliocaval venous compression syndrome (ICS) is the extrinsic compression of the common iliac vein by the overlying iliac artery against the vertebra. Chronic compression can lead to venous stenosis and stasis, which manifests as chronic venous disease and treatment resistance. Therefore, early recognition of ICS and prompt treatment are essential. Clinical presentations of ICS can be ambiguous and diagnosis requires a high index of suspicion with the relevant imaging studies. The initial imaging test is typically a Duplex ultrasound for vessel assessment and pelvic ultrasound to exclude a compressive mass, which is followed by computed tomography (CT) or magnetic resonance (MR) venography. CT and MRI can identify the anatomical causes for venous compression. In patients with high clinical suspicion for ICS, negative findings on CT and MR venography would still warrant further investigations. Definitive diagnosis can be established using catheter-based venography complemented with intravascular ultrasonography but the nature of their invasiveness limits its utility as a routine imaging modality. In this review paper, we will discuss the evidence, utility and limitations of the existing imaging modalities and endovascular intervention used in the management of ICS.

Diagnosis and Treatment of Nonthrombotic Right Iliac Vein Compression Syndrome

BACKGROUND

The anatomical etiology of right iliac vein compression syndrome (RIVCS) differs from that of left iliac vein compression syndrome. This study aimed to investigate the clinical features and therapeutic characteristics of RIVCS.

METHODS

Sixteen patients with nonthrombotic RIVCS were admitted to our hospital from May 2013 to July 2017. All patients underwent computed tomography venography (CTV) examinations of the right lower limb, which indicated that the right iliac veins were compressed by extrinsic structures. RIVCS was divided into 3 types according to the CTV findings. Stenting was conducted in patients with the appropriate indications. The superficial varicose veins in the lower limbs were simultaneously treated during endovascular treatment in a compound operating room. Antiplatelet therapy was administered after discharge.

RESULTS

Most RIVCS cases were types II and III, and the most frequently compressed segments were the middle and distal parts of the iliac vein. Most stents did not require stretching into the inferior vena cava and therefore seldom affected contralateral blood flow. Fifteen patients required stenting; the diameters of the stents ranged from 10 to 16 mm. All symptoms were alleviated, and the ulcers healed postoperatively. The remaining single patient with superficial varicose veins did not have an indication for endovascular therapy. During follow-up, all patients were symptom free, and the stents showed excellent patency.

CONCLUSIONS

CTV is a simple, accurate, and important method for diagnosing RIVCS. Endovascular therapy is an effective therapeutic method for RIVCS. Compared with the left side, stent implantation for RIVCS is safer and has fewer effects on contralateral blood flow.

Rivaroxaban or vitamin-K antagonists following early endovascular thrombus removal and stent placement for acute iliofemoral deep vein thrombosis

BACKGROUND

The optimal anticoagulant following catheter-based therapy of acute iliofemoral deep vein thrombosis (IFDVT) is unknown.

METHODS

From the Swiss Venous Stent registry, an ongoing prospective cohort study, we performed a subgroup analysis of patients with acute IFDVT who underwent catheter-based early thrombus removal followed by nitinol stent placement. Duplex ultrasound and Villalta scores were used to determine patency rates and incidence of the post-thrombotic syndrome (PTS) in patients treated with either rivaroxaban (n = 73) or a vitamin K-antagonist (VKA; n = 38) for a minimum duration of 3 months.

RESULTS

Mean follow-up duration was 24 ± 19 months (range 3 to 77 months). Anticoagulation therapy was time-limited (3 to 12 months) in 56% of patients (47% in the rivaroxaban group and 58% in the VKA group, p = 0.26), with shorter mean duration of anticoagulation in the rivaroxaban group (180 ± 98 days versus 284 ± 199 days, p = 0.01). Overall, primary and secondary patency rates at 24 months were 82% (95%CI, 71-89%) and 95% (95%CI, 87-98%), respectively, with no difference between the rivaroxaban (87% [95%CI, 76-94%] and 95% [95%CI, 85-98%]) and the VKA group (72% [95%CI, 52-86%] and 94% [95%CI, 78-99%]; p > 0.10 for both). Overall, 86 (86%) patients were free from PTS at latest follow-up, with no difference between the rivaroxaban and the VKA groups (57 [85%] versus 29 [88%]; p = 0.76). Two major bleeding complications (1 in each group) occurred in the peri-interventional period, without any major bleeding thereafter.

CONCLUSIONS

In patients with acute IFDVT treated with catheter-based early thrombus removal and venous stent placement, the effectiveness and safety of rivaroxaban and VKA appear to be similar.

CLINICAL TRIAL REGISTRATION

The study is registered on the National Institutes of Health website (ClinicalTrials.gov; identifier NCT02433054).

Thromboembolism in Cancer Patients: Pathogenesis and Treatment

In this review we summarize the causes of cancer related thrombosis as well as modern treatment approaches. Malignancy as a risk factor for thromboembolism is becoming increasingly recognized by clinicians caring for these patients. The probability of thrombosis occurring in an individual patient is dependent on several factors, including accompanying medical problems, the type of cancer, the clinical stage, performance status, and the treatment modalities employed. Thrombophilia with a history of thromboembolism is important as well. The overall risk of thrombosis is sevenfold that of noncancer patients. Though much has been learned about the pathogenesis of cancer-related thrombosis, we are in fact just beginning to understand the cross-talk between cancer cells and their related microenvironment, and such investigations are likely to increase our knowledge of cancer-related thrombosis mechanisms. Research in these areas may also suggest new strategies for cancer prevention, metastasis suppression, and new treatments. Drugs used in cancer therapy are increasingly recognized to directly contribute to the thrombotic tendency. Few studies provide data on the optimal management of cancer patients with thrombosis. It has been learned that retreating with the same drug can be very hazardous. In general the approach to prevention of thrombosis is the same as for noncancer patients, recognizing that specific cancer types and stage can place a patient in a high-risk category. Initial coumadin therapy fails in a significant number of patients with cancer. Recognition of the cancer patients at highest risk for coumadin failure is challenging. Low-molecular-weight heparins appear to be more effective in such situations where coumadin is likely to fail or has failed, but these drugs are thought to be costlier. Newer agents such as Factor Xa inhibitors and TF inhibitors are currently under investigation and may be found useful in the management of cancer-related thrombosis.

Chronic Venous Obstruction: Diagnostic Considerations and Therapeutic Role of Percutaneous Iliac Stenting

Iliac venous outflow obstruction has an important role in the expression of symptomatic chronic venous insufficiency. This anatomic obstruction is frequently overlooked, owing in part to diagnostic difficulty. The combination of venous obstruction and reflux leads to more severe clinical disease. Current diagnostic modalities do not allow an definitive assessment of hemodynamically critical venous obstruction. No single invasive or noninvasive study can accurately detect borderline obstruction of potential hemodynamic significance. A high index of suspicion is critical in the initial recognition of chronic venous obstruction. The diagnosis relies on clinical signs and symptoms and radiologic assessment of morphologic venous outflow obstruction. Treatment strategy should be based on the results of morphologic investigations such as transfemoral phlebography or, preferably, intravascular ultrasonography. Percutaneous iliac venous stenting offers a safe and efficient method to correct pelvic venous obstruction. Percutaneous iliac stenting does not preclude subsequent venous bypass or corrective superficial and deep reflux surgery. This article reviews the etiologic factors and diagnostic modalities of iliac venous obstruction. The therapeutic role of percutaneous iliac stenting in the management of venous obstruction is also discussed.

Optimal diagnostics of residual stenosis after lysis

The treatment of acute deep vein thrombosis has developed significantly over the past few years, and catheter-directed thrombolysis is now widely accepted. Controversy still exists over the decision to treat residual or underlying lesions with a venous stent. Magnetic resonance techniques have evolved considerably, which together with intravenous ultrasound can provide a detailed assessment of the deep venous system. Nevertheless, there is still no single perfect imaging modality that can identify a functional stenosis in the venous system. The decision to proceed to stent placement following lysis is multifactorial, reliant on the use of a number of imaging modalities in combination but most importantly good clinical acumen and experience.

Incidence and clinical significance of iliac vein compression

Objectives

To determine the frequency of left common iliac vein (CIV) compression by the right common iliac artery (CIA) based on CT scan images.

Methods

CT scan images were reviewed and the diameter of CIV was measured at the area of minimal diameter and compared to the distal adjacent segment and the contralateral CIV at the same level. Medical records were reviewed for symptoms, deep vein thrombosis (DVT) and risk factors that might be associated with DVT. Data were analyzed with SPSS program using both Chi square and t test. A p < 0.05 was considered statistically significant. Linear regression (R2) was used to evaluate correlation.

Results

A total of 300 complete records were reviewed. The mean age was 51.89 years, with 126 (42%) males. Comparison between the two groups (>70% vs <70%) showed similar clinical factors such as history of DVT, surgery, immobilization, malignancy, limb trauma, pregnancy, obesity, CHF, and smoking. There were more females with CIV compression of 70% or more than males (19.5% vs 11.1% P < .049).

Conclusion

Diameter stenosis more than 70% was present in 30.6% of cases with higher incidence in females. The presence of stenosis was not associated with the presence of clinical symptoms.

Value of magnetic resonance venography and computed tomographic venography in lower extremity chronic venous disease

For the treatment of chronic venous disease (CVD) of the lower extremity, identification of the underlying venous pathologies is essential. Traditionally, the pathologies to detect with imaging have been centred on insufficiency and reflux of the superficial, perforator and deep veins of the leg. More recently, stenosis and obstruction of the deep veins of the pelvis and abdomen (i.e. inferior vena cava, common and external iliac veins) have been identified as significant underlying pathologies in CVD. Accurate detection of stenotic and/or occlusive venous disease expands the treatment options for patients with CVD. In most cases, imaging of venous disease is performed with duplex ultrasound. In this article we discuss the existing evidence and potential value of computed tomographic venography and magnetic resonance venography to contribute in accurately identifying chronic venous disease, in particular chronic venous obstruction.

"Right-sided" May-Thurner syndrome

The May-Thurner syndrome is a well-known anatomical anomaly where the left common iliac vein (LCIV) is compressed between the right common iliac artery and the fifth vertebral body. This report describes the case of a "right-sided" May-Thurner syndrome where the right common iliac vein (RCIV) is compressed by the left common iliac artery in a patient with a left-sided inferior vena cava (IVC). A 26-year-old woman was admitted to our institution with acute edema of the right lower limb. The diagnosis of May-Thurner syndrome was done by CT scan and confirmed by phlebography. An endovascular treatment with stenting was carried out, with good patency and clinical result at 12-month follow-up.

Chronic deep venous obstruction: definition, prevalence, diagnosis, management

Ilio-caval venous obstruction has an important role in the expression of symptomatic chronic venous disease regardless of aetiology. The presence of obstruction has been more or less previously ignored and emphasis placed on reflux alone. Stenting of the ilio-femoral veins guided by intravascular ultrasound (IVUS) can now be performed with low morbidity and mortality using appropriate technique. Current diagnostic modalities do not allow a definitive assessment of haemodynamically critical venous obstruction, which hampers selection of limbs for treatment. The diagnosis must be based on morphological studies (preferably IVUS) in patient selected with specific history, signs and symptoms. A high index of suspicion and generous use of morphological investigations are critical in the initial recognition of venous outflow obstruction. Stenting of the ilio-femoral vein appears to be durable with a substantial improvement in limb pain and swelling, high rate of ulcer healing, enhanced quality of life and decreased disability. The beneficial clinical outcome occurs regardless of the presence of remaining reflux, adjunct saphenous procedures or aetiology of obstruction.

Stenting of the venous outflow in chronic venous disease: long-term stent-related outcome, clinical, and hemodynamic result

BACKGROUND

Stenting of chronic nonmalignant obstruction in the venous outflow tract started in earnest in 1997. Data sets are now available to perform long-term analysis of stent-related outcome and clinical and hemodynamic results of this intervention.

MATERIALS

From 1997 to 2005, 982 chronic nonmalignant obstructive lesions of the femoroiliocaval vein were stented under intravascular ultrasound guidance. Median patient age was 54 years (range, 14 to 90 years), the female/male was 2.6:1, and left/right limb symptoms, 2.4:1. Clinical score of CEAP was 2 in 7%, 3 in 47%, 4 in 24%, 5 in 5%, and 6 in 17%; primary/secondary etiology was 518:464. Stent-related outcome (morbidity, thrombotic events, patency, in-stent recurrent stenosis), clinical outcome, quality of life (QOL) as assessed by the Chronic Venous Insufficiency Quality of Life Questionnaire (CIVIQ), and hemodynamics were evaluated before and after intervention.

RESULT

Monitoring for 94% of patients lasted a mean 22 months (range, 1 to 107 months). Stenting was performed with no mortality (<30 days) and low morbidity. Thrombotic events were rare (1.5%) during the postoperative period (<30 days) and during later follow-up (3%). At 72 months, primary, assisted-primary, and secondary cumulative patency rates were 79%, 100%, and 100% in nonthrombotic disease and 57%, 80%, and 86% in thrombotic disease, respectively. Cumulative rate of severe in-stent restenosis (>50%) occurred in 5% of limbs at 72 months (10% in thrombotic limbs, 1% in nonthrombotic limbs). The main risk factors associated with stent occlusion were the presence and severity of thrombotic disease; thrombophilia by itself was not a risk factor. The median pain score and degree of swelling decreased significantly poststent. Severe leg pain (visual analogue scale >5) and leg swelling (grade 3) decreased from 54% and 44% prestent to 11% and 18% poststent, respectively. At 5 years, cumulative rates of complete relief of pain and swelling were 62% and 32%, respectively, and ulcer healing was 58%. The mean CIVIQ scores of QOL improved significantly in all categories. Mean hand-foot pressure differential decreased and mean ambulatory venous pressure improved in stented limbs with no concomitant reflux. The hemodynamic response was modified, depending on the presence of deep and superficial reflux in subsets of patients with adjunct saphenous procedures. No increase in venous reflux was observed.

CONCLUSIONS

Venous stenting can be performed with low morbidity and mortality, long-term high patency rate, and a low rate of in-stent restenosis. It resulted in major symptom relief in patients with chronic venous disease, which was not consistently reflected in any substantial hemodynamic improvement by conventional measurements. The beneficial clinical outcome occurred regardless of presence of remaining reflux, adjunct saphenous procedures, or etiology of obstruction.