Intravascular Ultrasound-Guided Intervention for May-Thurner Syndrome

Efficacy of ultrasound in the evaluation of iliac vein stenting

Objectives: The current study evaluated the efficacy of iliac and IVC ultrasound alone for follow-up evaluation of iliac vein stents in patients with pelvic venous disorders or iliac occlusion from chronic deep vein thrombosis. Methods: A retrospective single site cohort study was conducted by evaluating the most recent 100 iliac vein and inferior vena cava ultrasounds in patients who had undergone iliac vein stenting. Inclusion criteria included a history of iliac vein stent placement. Exclusion criteria included patients under 18-years-old, duplicates of the same patient, and pregnancy at the time of ultrasound. The degree of visualization for color flow, gray scale, and phasicity were determined and classified into the following categories: complete, partial, or none. In addition, each chart was assessed for external compression, in-stent narrowing, and requirements for further imaging. Results: Of the 100 iliac vein and IVC ultrasounds assessed in this review, 99 of the ultrasounds were sufficient for evaluation during follow-up visits without requiring further investigation. Within this study cohort, the average follow-up time was 22 months. The average participant body mass index was 27.6. One iliac vein and IVC ultrasound was considered inadequate for follow-up evaluation and required further imaging. Conclusion: The use of iliac and IVC venous doppler ultrasound alone in the follow-up evaluation of iliac stent patency is effective and noninvasive and avoids unnecessary radiation exposure and cost.

Unveiling May-Thurner Syndrome in a Case of Recurrent Deep Venous Thrombosis With Bilateral Pulmonary Embolism

May-Thurner syndrome (MTS) is a rare cause of deep venous thrombosis (DVT), characterized by the external compression of the left common iliac vein by the right common iliac artery against bony structures. Risk factors for MTS include female sex (postpartum, multiparous, and using oral contraceptive pills), spinal abnormalities like scoliosis, prior aortoiliac vascular stent placement, dehydration, and hypercoagulability. MTS patients with partial obstruction can be asymptomatic, but progression to extensive symptomatic DVT and/or chronic venous insufficiency can occur. MTS can be diagnosed by non-invasive imaging studies including ultrasound (US), computed tomography (CT) scan, magnetic resonance imaging (MRI), venogram, catheter-based venogram, and intravascular US. For MTS patients with moderate to severe symptoms, we suggest thrombectomy, angioplasty, and stenting of the affected segment. In this case report, we highlight a 44-year-old male with a recent diagnosis of left-sided DVT on apixaban who presented with worsening leg swelling. DVT, pulmonary embolism (PE), and MTS were diagnosed with a lower extremity US, chest CT angiography, and abdominal/pelvic CT scan and venography, respectively. The patient underwent interventional radiology-guided local thrombolysis, thrombectomy, and venoplasty along with stent placement in the left common iliac vein. Subsequently, the patient was discharged on rivaroxaban.

Endovascular resolution of complete common iliac vein stenosis in a case of May-Thurner syndrome with underlying malignancy

INTRODUCTION AND IMPORTANCE

May-Thurner Syndrome (MTS) is an uncommon etiology of left common iliac vein thrombosis due to arterial compression. In this report, we describe a case of MTS with severe occlusion of the left common iliac vein in the context of a previously undiagnosed pancreatic cancer. We detail the endovascular resolution of the iliac vein compression and show long-term patency.

CASE PRESENTATION

A 33-year-old woman on oral contraceptive pills presented with extensive thrombosis of the left common iliac vein extending cephalad into the lower IVC and inferiorly to the femoral vein. The thrombus was refractory to therapeutic heparin. Mechanical thrombectomy removed the occluding thrombus. Intravenous ultrasound identified severe compression of the left common iliac vein by the right common iliac artery. Angioplasty and stenting provided complete resolution of the lesion. Imaging and hematologic workup revealed a pancreatic malignancy and concomitant hypercoagulable state that likely precipitated the patient's presentation.

CLINICAL DISCUSSION

Endovascular intervention provided complete resolution of severe iliac vein compression. Patency was maintained at 6-month follow-up. Research suggests that the anatomical lesion predisposing individuals to MTS is relatively common despite infrequent occurrence of the syndrome. This case highlights the importance of a high clinical suspicion for associated hypercoagulable states when MTS is discovered.

CONCLUSION

There is limited research exploring the relationship between severity of iliac vein compression and endovascular treatment outcome. This case documents endovascular resolution of a severe lesion with maintained patency.

Intravascular ultrasound for endovascular precision in pediatrics

Intravascular ultrasound (IVUS) is used as a diagnostic adjunct to angiography and has become a valuable diagnostic and interventional tool with a well-documented safety profile. The American College of Cardiology and the European Society of Cardiology have published guidelines regarding the use of IVUS in the setting of percutaneous coronary intervention. IVUS has gained popularity in the interventional radiology (IR) community in recent years; however, there are no consensus guidelines for utilization. Furthermore, IVUS remains an infrequently used modality in pediatric IR, likely because of unfamiliarity with the equipment and techniques, as well as concerns over the compatibility of these instruments with pediatric anatomy. IVUS can be safely used as a helpful and sometimes necessary tool for pediatric interventions in appropriately selected patients. The utility of IVUS for reducing both fluoroscopy time and contrast agent volume makes it particularly valuable in pediatric practice. This article presents an overview of both the rotational and phased-array IVUS types and an in-depth discussion on the most common applications of these techniques in the pediatric setting across multiple procedure categories.

Prevalence of left iliac vein compression on computed tomography scans from a population

BACKGROUND

May-Thurner syndrome (MTS) is defined as compression of the left iliac vein between the right iliac artery and the lumbar vertebral body in the presence of signs and symptoms of unilateral left chronic venous insufficiency. However, imaging findings of compression are not manifest in symptoms of the syndrome in all subjects.

OBJECTIVES

To evaluate findings of compression in an asymptomatic population.

METHODS

Computed tomography angiographies or venous phase computed tomographies were analyzed. Demographic data and reason for the exam were recorded. Vein diameter was measured at the site of greatest compression and distal of the compression and the ratio between the two diameters was calculated.

RESULTS

From January to July of 2016, 590 computed tomography scans were analyzed (357 women and 233 men). Left iliac compression was found in 14.74% of patients. Patients with a left iliac diameter below the 5mm threshold had a mean diameter at the site of greatest iliac vein compression of 4.4 mm (range: 2.67 mm-4.97 mm). The ratio between the two measurements was < 0.5 in 30% of patients.

CONCLUSIONS

Our study suggests that iliac vein compression is common among random patients who have had computed tomography for any other reason. This indicates that compression found on tomography images is not the only finding to consider when treating a patient.

May-Thurner syndrome: History of understanding and need for defining population prevalence

Patients with May-Thurner syndrome (MTS) are at elevated risk of developing an extensive left iliofemoral deep vein thrombosis (DVT; localized blood clot) due to an anatomical variant where the right common iliac artery compresses the left common iliac vein against the lumbar spine. While MTS was initially presumed to be rare when it was first anatomically defined in 1957, case reports of this syndrome have recently become more frequent, perhaps due to improved imaging techniques allowing for enhanced visualization of the iliac veins. Still, the population burden of this condition is unknown, and there is speculation it may be higher than generally perceived. In the present review, we (a) review history of how MTS became recognized, (b) describe practical challenges of studying MTS in population-based settings due to the specialized imaging required for diagnosis, (c) discuss why the contribution of MTS to DVT may be underestimated, (d) describe uncertainty regarding the degree of venous compression which leads to DVT, and (e) outline future research needs. Our goal is to raise awareness of MTS and spark additional research into the epidemiology of this condition, which may be an underappreciated causative venous thromboembolism risk factor.

Intravascular Ultrasound for the Peripheral Vasculature-Current Applications and New Horizons

Intravascular ultrasound (IVUS) is a proven and rapidly developing imaging modality that can be used for a multitude of both diagnostic and interventional purposes. By allowing for superior intraluminal characterization, compared with angiography, IVUS has emerged as a technically valuable tool in interventional procedures such as transjugular intrahepatic portosystemic shunt/direct intrahepatic portosystemic shunt, venous interventions (May Thurner stenting, inferior vena cava filter placement, recanalization in the setting of chronic venous thrombosis/insufficiency), percutaneous fenestration in the setting of aortic dissection and angioplasty. Additional applications evaluating coronary arteries and plaque morphology have been described, but are outside the scope of this review. In addition to IVUS's merit as a pre- and intra-procedural guidance modality, there are also several advantages compared to the gold standard of angiography which include decreased need for iodinated contrast, decreased radiation exposure and decreased procedural times in certain cases. With current research, such as that aimed at supraharmonic imaging, further improvements in imaging depth, resolution and contrast to noise ratio are on the horizon.

Mid-and long-term efficacy of endovascular-based procedures for Cockett syndrome

To investigate the mid- and long-term results of endovascular-based procedures for Cockett syndrome. The clinical data of 412 patients with Cockett syndrome treated between January 2003 and September 2017 were retrospectively analyzed. In these patients, 231 cases were acute left iliac femoral vein thrombosis (group A), and 181 cases were chronic venous insufficiency (group B), and different endovascular procedures and/or hybrid procedures were performed. In group A, the technique success rate was 100% (231/231); the left iliac vein in 5 patients showed no stenosis or occlusion, and the incidence of pathological changes in the left iliac vein was 97.8% (226/231); a total of 182 stents were implanted. In group B, the technique success rate was 99.4% (180/181); the average pressure difference between the proximal and distal portion of the pathological left iliac veins decreased from preoperative (18 ± 4.45) cmH2O to postoperative (4 ± 3.02) cmH2O (P < 0.01); 89 patients, complicated with valvular incompetence in the left superficial femoral vein, underwent a second-stage femoral valve repair. Follow-up ranged from 3 months to 8 years, with an average of 35.6 months, and intrastent thrombosis occurred in 15 cases of group A and in 2 cases of group B. Endovascular-based procedures offer favorable mid- and long-term results in treatment of Cockett syndrome, which in combination with Fogarty catheter thrombectomy or catheter-directed thrombolysis is a beneficial complementary treatment for patients with acute iliac femoral vein thrombosis.