Percutaneous mechanical and pharmacomechanical thrombolysis for occlusive deep vein thrombosis of the proximal limb in adolescent subjects: findings from an institution-based prospective inception cohort study of pediatric venous thromboembolism

Technical Feasibility and Clinical Efficacy of Iliac Vein Stent Placement in Adolescents and Young Adults with May-Thurner Syndrome

PURPOSE

To report technical feasibility and clinical efficacy of iliac vein stent placement in adolescent patients with May-Thurner Syndrome (MTS).

MATERIALS AND METHODS

Single-institution retrospective review of the medical record between 2014 and 2021 found 63 symptomatic patients (F = 40/63; mean age 16.1 years, 12-20 years) who underwent left common iliac vein (LCIV) stent placement for treatment of LCIV compression from an overriding right common iliac artery, or equivalent (n = 1, left IVC). 32/63 (50.7%) patients presented with non-thrombotic iliac vein lesions (NIVL). 31/63 (49.2%) patients presented with deep vein thrombosis of the lower extremity and required catheter-directed thrombolysis after stent placement (tMTS). Outcomes include technically successful stent placement with resolution of anatomic compression and symptom improvement. Stent patency was monitored with Kaplan-Meier analysis at 3, 6, 12, 24, and 36 months. Anticoagulation and antiplatelet (AC/AP) regimens were reported.

RESULTS

Technical success rate was 98.4%. 74 bare-metal self-expanding stents were placed in 63 patients. Primary patency at 12, and 24-months was 93.5%, and 88.9% for the NIVL group and 84.4% and 84.4% for the tMTS group for the same period. Overall patency for the same time intervals was 100%, and 95.4% for the NIVL group and 96.9%, and 96.9% for the tMTS group. Procedural complication rate was 3.2% (2/63) with no thrombolysis-related bleeding complications. Clinical success was achieved in 30/32 (93.8%) and 29/31 (93.5%) patients with tMTS and NIVL groups, respectively.

CONCLUSION

CIV stent placement in the setting of tMTS and NIVL is technically feasible and clinically efficacious in young patients with excellent patency rates and a favorable safety profile.

Society of Interventional Radiology Position Statement on the Endovascular Management of Acute Iliofemoral Deep Vein Thrombosis

PURPOSE

To establish the updated position of the Society of Interventional Radiology (SIR) on the endovascular management of acute iliofemoral deep vein thrombosis (DVT).

MATERIALS AND METHODS

A multidisciplinary writing group with expertise in treating venous diseases was convened by SIR. A comprehensive literature search was conducted to identify studies on the topic of interest. Recommendations were drafted and graded according to the updated SIR evidence grading system. A modified Delphi technique was used to achieve consensus agreement on the recommendation statements.

RESULTS

A total of 84 studies, including randomized trials, systematic reviews and meta-analyses, prospective single-arm studies, and retrospective studies were identified and included in the review. The expert writing group developed 17 recommendations that pertain to the care of patients with acute iliofemoral DVT with the use of endovascular venous interventions.

CONCLUSIONS

SIR considers endovascular thrombus removal to be an acceptable treatment option in selected patients with acute iliofemoral DVT. Careful individualized risk assessment, high-quality general DVT care, and close monitoring during and after procedures should be provided.

Clinical characteristics, management strategies and outcomes of patients with recurrent venous thromboembolism in the real world

There is a paucity of data on management strategies and clinical outcomes after recurrent venous thromboembolism (VTE). In a multicenter registry enrolling 3027 patients with acute symptomatic VTE, the current study population was divided into the following 3 groups: (1) First recurrent VTE during anticoagulation therapy (N = 110); (2) First recurrent VTE after discontinuation of anticoagulation therapy (N = 116); and (3) No recurrent VTE (N = 2801). Patients with first recurrent VTE during anticoagulation therapy more often had active cancer (45, 25 and 22%, P < 0.001). Among 110 patients with first recurrent VTE during anticoagulation therapy, 84 patients (76%) received warfarin at recurrent VTE with the median prothrombin time-international normalized ratio (PT-INR) value at recurrent VTE of 1.6, although patients with active cancer had a significantly higher median PT-INR value at recurrent VTE compared with those without active cancer (2.0 versus 1.4, P < 0.001). Within 90 days after recurrent VTE, 23 patients (20.9%) during anticoagulation therapy and 24 patients (20.7%) after discontinuation of anticoagulation therapy died. Active cancer was a major cause of recurrent VTE during anticoagulation therapy as a patient-related factor, while sub-optimal intensity of anticoagulation therapy was a major cause of recurrent VTE during anticoagulation therapy as a treatment-related factor, particularly in patients without active cancer.

Successful treatment of an adolescent patient with acute subclavian vein occlusion using the Cleaner thrombectomy device

Paget-Schroetter Syndrome is a rare condition characterized by the thrombosis of the axillary and/or subclavian vein due to repetitive activity of the upper extremity. This effect results in exertion-induced deep venous thrombosis (DVT) of the upper extremity. In the literature, it has been reported more frequently among the adult population. We aimed to introduce a 15-year-old female patient who suffered an acute DVT of the left upper extremity, and her successful treatment using the Cleaner thrombectomy device.

Successful Secondary Endovascular Intervention in Pediatric Patients with Venous Thromboembolic Events

BACKGROUND

 In the past, pediatric patients with venous thromboembolic events (VTE) were treated with low-molecular-weight heparin (LMWH) which was successful in around 70% of the cases. However, anticoagulation alone might not restore patency in all patients, and advanced therapeutic options to prevent postthrombotic syndrome are needed. During recent years, endovascular interventions have become a treatment option for pediatric patients with persistent thrombotic occlusion, not only in life- or limb-threatening VTE.

METHODS

 We evaluated 12 consecutive patients (11-17 years) with newly diagnosed VTE being treated at our department during the last 4 years (2017-2020). In case follow-up examination showed persistent venoocclusion under anticoagulation, patients received secondary interventional therapy like recanalization, percutaneous transluminal angioplasty with or without catheter-directed thrombolysis, and stenting. Patients with no clinical signs of venoocclusion or regredient thrombosis in imaging examination received anticoagulation alone.

RESULTS

 Six of 12 (50%) patients underwent catheter intervention. Median time from diagnosis to intervention was 4 months (0-12 months). Reintervention was necessary in one (8%) case and complete recanalization failed in one (8%) case. There were no major bleeding events or other major postinterventional complications, no acute or late local recurrence, and all patients reported clinical improvement after the procedure.

CONCLUSION

 If endovascular intervention is used in teenage patients with persistent symptomatic VTE, reduction of postthrombotic symptoms is possible, even if intervention is performed secondary to failure of anticoagulation. Multidisciplinary treatment decisions can be based on the clinical course and follow-up imaging.

Clinical characteristics and outcomes of combined thrombolysis and anticoagulation for pediatric and young adult lower extremity and inferior vena cava thrombosis

Effective treatment for acute, extensive, symptomatic lower extremity (LE) thrombosis involves thrombolysis in addition to anticoagulation. There is limited available data on the outcomes and safety of thrombolysis to help guide its use in pediatrics and young adults. A retrospective study of children and young adults (<21 years of age) that received catheter directed thrombolysis (CDT) for LE and inferior vena cava (IVC) thrombosis was performed over a 5-year span at a pediatric tertiary care center. A total of 29 patients were identified for inclusion in the study, 76% (n = 22) received overnight CDT while 24% (n = 7) received tissue plasminogen activator as a bolus dose during a single interventional procedure. The median age of the cohort was 15.8 years (range 0-19.1). All patients were treated with a course of therapeutic anticoagulation. The thromboses represented were extensive, with 93% (n = 27) being occlusive and affecting multiple venous segments. Thrombus resolution occurred in 35% (n = 10) of patients. Rivaroxaban use (p < 0.01) during the course of anticoagulation and estrogen-containing hormonal therapy (p = 0.01) use prior to diagnosis were associated with thrombus resolution, while Hispanic ethnicity (p = 0.06) had a trend toward thrombus persistence. There were one major and 3 minor bleeding events that occurred as complications of thrombolysis and no treatment related deaths. This study provides baseline information that can be used to help guide clinicians treating similar patients and suggests the need to develop an improved, uniform treatment approach for superior resolution rates.

Validation of Outcome Instruments for Pediatric Postthrombotic Syndrome: Introducing the Peds-VEINES-QOL, a New Health-Related Quality of Life Instrument

BACKGROUND

 There is need for validated outcome measures for postthrombotic syndrome (PTS) following pediatric venous thromboembolism (VTE), with a focus on quality of life (QoL).

AIMS

 This article assesses reliability and validity of two PTS and two QoL scales for children following lower extremity VTE.

METHODS

 Pediatric patients following lower extremity VTE were recruited from three thrombosis clinics. The Manco-Johnson (MJ) and the modified Villalta (MV) PTS scales were compared with each other and with the generic pediatric health-related QoL, PedsQL, and a newly developed pediatric venous-specific QoL, the Peds-VEINES-QOL.

RESULTS

 Eighty children following VTE and 60 healthy control children were enrolled. Internal consistency measured by Cronbach's α was high for the two QoL scales, and moderate for the two PTS scales. Inter-rater reliability using intraclass correlation coefficients was moderate to high for the MJ, MV, and Peds-VEINES-QOL, and moderate for the PedsQL. Evidence of high internal consistency by Cronbach's α coefficients, and moderate to high interitem correlations support the premise that a single construct was measured by each instrument. Correlations between the four instruments indicate convergent validity.

CONCLUSION

 The MJ and MV scales detect similar outcomes in children following VTE. As used, the MJ is slightly more sensitive to QoL because a positive diagnosis requires pain which is the leading factor in reduced QoL following deep vein thrombosis. When using the MV, a requirement for pain or abnormal use to diagnose PTS would make the MV a better predictor of QoL.

Thrombolysis in Children: A Case Report and Review of the Literature

Thromboembolism (TE), including venous thromboembolism (VTE), arterial TE, arterial ischemic stroke (AIS), and myocardial infarction (MI), is considered a relatively rare complication in the pediatric population. Yet, the incidence is rising, especially in hospitalized children. The vast majority of pediatric TE occurs in the setting of at least one identifiable risk factor. Most recently, acute COVID-19 and multisystem inflammatory syndrome in children (MIS-C) have demonstrated an increased risk for TE development. The mainstay for the management pediatric TE has been anticoagulation. Thrombolytic therapy is employed more frequently in adult patients with ample data supporting its use. The data for thrombolysis in pediatric patients is more limited, but the utilization of this therapy is becoming more commonplace in tertiary care pediatric hospitals. Understanding the data on thrombolysis use in pediatric TE and the involved risks is critical before initiating one of these therapies. In this paper, we present the case of an adolescent male with acute fulminant myocarditis and cardiogenic shock likely secondary to MIS-C requiring extracorporeal life support (ECLS) who developed an extensive thrombus burden that was successfully resolved utilizing four simultaneous catheter-directed thrombolysis (CDT) infusions in addition to a review of the literature on the use of thrombolytic therapy in children.

Clinical Outcomes of May-Thurner Syndrome in Pediatric Patients: A Single Institutional Experience

Introduction  May-Thurner syndrome (MTS) is a vascular anatomic variant resulting in compression of the left common iliac vein by the right common iliac artery, affecting approximately 22% of the population. In adults, following acute deep vein thrombosis (DVT) of the iliofemoral veins, the incidence of postthrombotic syndrome (PTS) and recurrent DVT are high if treated with anticoagulation alone, warranting adjunctive treatment with thrombolysis and stent placement. However, there is paucity of literature documenting the course of treatment and associated outcomes in pediatric patients with MTS. Methods  A retrospective chart review of pediatric patients (≤ 18 years of age) with radiologic confirmation of MTS with or without DVT evaluated and/or treated at our institution from January 1, 2005 through December 31, 2015 was conducted. Results  Seventeen patients (4 male; 13 female) were identified. Median age was 15.4 years (range 8.8-17.1 years) with a median follow-up of 1.2 years (range 0.4-7.5 years). Thirteen (76.5%) patients presented with left lower extremity DVT. Management included catheter-directed thrombolysis ( n  = 5), systemic thrombolysis ( n  = 1), and mechanical thrombectomy ( n  = 1). Fifteen patients were treated with anticoagulation including two patients with endovascular stents without DVT. Median duration of anticoagulation was 6.3 months (range 3.2-18.7 months). Ten patients (59%) underwent stent placements. Complete and partial thrombus resolution was noted in six patients each and no resolution in one patient. Four patients had recurrence/progression of thrombus ( n  = 3 with stents) at a median time of 29 days (range 12-495 days). No bleeding complications were observed. Clinically documented or self-reported PTS was noted in 8 patients (62%). Conclusion  There are no clear guidelines for MTS management in children and adolescents. In our cohort, thrombolysis, anticoagulation, or stent placements were not associated with bleeding risks, with recurrence/progression of DVT and signs and symptoms of PTS noted in 30 and 62%, respectively. Further studies are needed to determine a standardized treatment approach of the pediatric patient with MTS with or without thrombosis.

A review into the management of May-Thurner syndrome in adolescents

OBJECTIVE

To investigate the presentation, etiology, management and outcomes of May-Thurner syndrome (MTS) in adolescents aged under 18.

METHODS

We searched electronic bibliographic databases to identify published reports of MTS in patients under 18 years of age. We conducted our review according to the PRISMA statement standards.

RESULTS

Ten studies encompassing 22 patients treated for MTS in adolescent cases were identified. The mean age of patients was 15 years (range, 10-18 years). Of the 22 patients, 12 (55%) were confirmed to have proximal deep vein thrombosis as the primary indication for intervention. Treatment methods included catheter-directed thrombolysis and iliac vein stenting (41%), pharmacomechanical thrombolysis and iliac vein stenting (18%), iliac vein stenting alone (27%), open surgery (14%), catheter-directed thrombolysis (5%), and anticoagulation alone (5%). Complications were infrequent. All studies reported subjective improvements in clinical symptoms with only two studies using validate outcome measures. In total, 9 of 22 patients (41%) had addition risk factors that may precipitate thrombosis.

CONCLUSIONS

As in adults, the most common form of treatment seen in the literature is a combination of catheter direct thrombolysis, followed by iliac vein stenting with subsequent anticoagulation. Complications from interventions were low. It is unclear how these interventions affect symptomology and the long-term sequalae associated endovascular surgery and stenting in adolescents. Further research is needed in well-designed studies with adequate follow-up.

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.

Treatment of venous thromboembolism in pediatric patients

Venous thromboembolism (VTE) is rare in healthy children, but is an increasing problem in children with underlying medical conditions. Pediatric VTE encompasses a highly heterogenous population, with variation in age, thrombosis location, and underlying medical comorbidities. Evidence from pediatric clinical trials to guide treatment of VTE is lacking so treatment is often extrapolated from adult trials and expert consensus opinion. Aspects unique to children include developmental hemostasis and the major role of central venous access devices. There is an absence of information regarding the optimal target levels of anticoagulation for neonates and infants and lack of suitable drug formulations. Anticoagulants, primarily low-molecular-weight heparin and warfarin, are used to treat children with symptomatic VTE. These drugs have significant limitations, including the need for subcutaneous injections and frequent monitoring. Randomized clinical trials of direct oral anticoagulants in pediatric VTE are ongoing, with results anticipated soon. These trials will provide new evidence and options for therapy that have the potential to improve care. International collaborative registries offer the ability to study outcomes of rare subgroups of pediatric VTE (eg, renal vein thrombosis), and will be important to ultimately guide therapy in a more disease-specific manner.

Massive Fatal Pulmonary Embolism While on Therapeutic Heparin Drip

Venous thromboembolism (VTE) includes deep venous thrombosis (DVT) and pulmonary embolism (PE). In this article, we present a case of a patient with an acute DVT who was treated with a therapeutic heparin drip, then developed syncope while in the hospital and found to have massive bilateral PEs. This case aims to arouse the medical staff’s awareness of the VTE diagnosis even if the patient is fully anticoagulated. We review the indications for DVT hospitalization, heparin infusion monitoring, risk factors for developing PE from DVT, mechanisms of developing PE from DVT while on therapeutic anticoagulation, and signs and treatment of massive PE.

Thromboprophylaxis strategies for children with single-ventricle circulations (superior or total cavo-pulmonary connections) after stent implantation

OBJECTIVE

To define optimal thromboprophylaxis strategy after stent implantation in superior or total cavopulmonary connections.

BACKGROUND

Stent thrombosis is a rare complication of intravascular stenting, with a perceived higher risk in single-ventricle patients.

METHODS

All patients who underwent stent implantation within superior or total cavopulmonary connections (caval vein, innominate vein, Fontan, or branch pulmonary arteries) were included. Cohort was divided into aspirin therapy alone versus advanced anticoagulation, including warfarin, enoxaparin, heparin, or clopidogrel. Primary endpoint was in-stent or downstream thrombus, and secondary endpoints included bleeding complications.

RESULTS

A total of 58 patients with single-ventricle circulation underwent 72 stent implantations. Of them 14 stents (19%) were implanted post-superior cavopulmonary connection and 58 (81%) post-total cavopulmonary connection. Indications for stenting included vessel/conduit stenosis (67%), external compression (18%), and thrombotic occlusion (15%). Advanced anticoagulation was prescribed for 32 (44%) patients and aspirin for 40 (56%) patients. Median follow up was 1.1 (25th-75th percentile, 0.5-2.6) years. Echocardiograms were available in 71 patients (99%), and advanced imaging in 44 patients (61%). Thrombosis was present in two patients on advanced anticoagulation (6.3%) and none noted in patients on aspirin (p = 0.187). Both patients with in-stent thrombus underwent initial stenting due to occlusive left pulmonary artery thrombus acutely post-superior cavopulmonary connection. There were seven (22%) significant bleeding complications for advanced anticoagulation and none for aspirin (p < 0.001).

CONCLUSIONS

Antithrombotic strategy does not appear to affect rates of in-stent thrombus in single-ventricle circulations. Aspirin alone may be sufficient for most patients undergoing stent implantation, while pre-existing thrombus may warrant advanced anticoagulation.

Lower extremity endovenous reconstruction for symptomatic occlusive disease in pediatric patients: techniques, clinical outcomes, and long-term stent patencies

BACKGROUND

Endovascular stent reconstruction is the standard of care for chronic venous occlusive disease in adults, but it has not been reported in pediatric patients.

OBJECTIVE

This study reports the technical success, complications, clinical outcomes, and stent patency of iliocaval stent reconstruction for chronic iliocaval thrombosis in pediatric patients.

MATERIALS AND METHODS

Fourteen patients, 13 (93%) male with a mean age of 16.4 years (range: 8-20 years), underwent iliocaval stent reconstruction for chronic iliocaval thrombosis. The mean number of prothrombotic risk factors was 2.5 (range: 0-4), including 7 (50%) patients with inferior vena cava atresia. At initial presentation, the Clinical, Etiology, Anatomy, and Pathophysiology classification (CEAP) score was C3 in 2 (14%) patients, C4 in 11 (79%) patients, and C6 in 1 (7.1%) patient. Time course of presenting symptoms included chronic (>4 weeks) (n=7; 50%) and acute worsening of chronic symptoms (2-4 weeks) (n=7; 50%). Aspects of recanalization and reconstruction, stenting technical success, complications, clinical outcomes and stent patency were recorded. Clinical success was defined as a 1-point decrease in the CEAP. Primary, primary-assisted, and secondary patency were defined by Cardiovascular and Interventional Radiological Society of Europe guidelines.

RESULTS

Most procedures employed three access sites (range: 2-4). Intravascular ultrasound was employed in 11 (79%) procedures. Blunt and sharp recanalization techniques were used in 12 (86%) and 2 (14%) patients, respectively. Stenting technical success was 100%. Two (14%) minor adverse events occurred and mean post-procedure hospitalization was 2.8 days (range: 1-8 days). Clinical success rates at 2 weeks, 6 months and 12 months were 85%, 82%, and 83%, respectively. At a mean final clinical follow-up of 88 months (range: 16-231 months), clinical success was 93%. Estimated 6- and 12-month primary stent patencies were 86% and 64%, respectively. Six- and 12-month primary-assisted and secondary stent patency rates were both 100%.

CONCLUSION

Iliocaval stent reconstruction is an effective treatment for symptomatic chronic iliocaval thrombosis in pediatric patients with high rates of technical success, 6- and 12-month clinical success, and 6- and 12-month primary-assisted and secondary patency rates.

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.

A systematic review of paediatric deep venous thrombolysis

Objectives

The aim was to assess the effectiveness and safety of catheter-directed thrombolysis in children with deep venous thrombosis and to evaluate its long-term effect.

Method and results

EMBASE, Medline and Cochrane databases were searched to identify studies in which paediatric acute deep venous thrombosis patients received thrombolysis. Following title and abstract screening, seven cohort studies with a total of 183 patients were identified. Technical success was 82% and superior in regional rather than systemic thrombolysis (p < 0.00001). One cohort study identified significant difference in thrombus resolution at one year between thrombolytic and anticoagulant groups (p = 0.01). The complication rate was low, with incidence rates of major bleeding, pulmonary embolism and others at 2.8%, 1.8% and 8.4%, respectively. The overall post-thrombotic syndrome rate was 12.7%. The incidence of re-thrombosis ranged from 12.3% to 27%.

Conclusion

Thrombolysis for paediatric deep venous thrombosis is an effective and relatively safe therapeutic option, lowering the incidence of post-thrombotic syndrome and deep venous thrombosis recurrence.

A systematic review on the use of deep venous stenting for acute venous thrombosis of the lower limb

OBJECTIVES

The aim is to evaluate venous stent patency, the development of post-thrombotic syndrome, recurrence, quality of life and the optimal post-procedural anticoagulation regimen in the treatment of iliofemoral deep venous thrombosis.

METHOD AND RESULTS

EMBASE and Medline databases were interrogated to identify studies in which acute deep venous thrombosis patients were stented. Twenty-seven studies and 542 patients were identified. Primary, assisted primary and secondary patency rates 12 months after stent placement ranged from 74 to 95, 90 to 95 and 84 to 100%, respectively. The observed post-thrombotic syndrome rate was 14.6%. The incidence of stent re-thrombosis was 8%. In 26% of studies, patients received additional antiplatelet therapy. Quality of life questionnaires employed in 11% of studies, demonstrating an improvement in the chronic venous insufficiency questionnaire (22.67 ± 3.01 versus 39.34 ± 6.66).

CONCLUSION

Venous stenting appears to be an effective adjunct to early thrombus removal; however, further studies are needed to identify optimal anticoagulant regimen and effect on quality of life.

Pulmonary embolism and in situ pulmonary artery thrombosis in paediatrics

Data on paediatric pulmonary embolism (PE) are scarce. We sought to systematically review the current literature on childhood PE and conducted a search on paediatric PE via PubMed (1946–2013) and Embase (1980–2013). There was significant heterogeneity in reported data. Two patterns were noted: classic thromboembolic PE (TE-PE) and in situ pulmonary artery thrombosis (ISPAT). Mean age of presentation for TE-PE was 14.86 years, and 51% of cases were males. The commonest method for diagnosis of TE-PE was contrast CT with angiography (74% of patients). The diagnosis of TE-PE was often delayed. Although 85% of children with TE-PE had an elevated D-dimer at presentation, it was non-discriminatory for the diagnosis. In paediatric TE-PE, the prevalence of central venous catheters was 23%, immobilisation 38%, systemic infection 31% and obesity 13%, elevated Factor VIII or von Willebrand factor levels 27%, Protein C deficiency 17%, Factor V Leiden 14% and Protein S deficiency 7%. In patients with TE-PE, pharmacologic thrombolysis was used in 29%; unfractionated heparin was the most common initial anticoagulant treatment in 64% and low-molecular-weight heparins the most common follow-up treatment in 83%. Duration of anticoagulant therapy was variable and death was reported in 26% of TE-PE patients. In contrast to TE-PE, patients with ISPAT were not investigated systematically for presence of thrombophilia, had more surgical interventions as the initial management and were often treated with anti-platelet medications. This review summarises important data and identifies gaps in the knowledge of paediatric PE, which may help to design future studies.

How I treat recurrent venous thromboembolism in patients receiving anticoagulant therapy

Oral anticoagulant therapy for venous thromboembolism is very effective. When oral anticoagulants are managed well, the risk of recurrence is approximately 2 per 100 patient-years. The main reasons for a breakthrough event are underlying disease and subtherapeutic drug levels. The most common underlying disease that results in recurrence on treatment is cancer. Subtherapeutic drug levels can be caused by poor adherence to the drug regimen, interactions with other drugs or food, or inappropriate dosing. It is important to investigate and understand the cause whenever such an event occurs and to improve management of anticoagulants thereby avoiding further recurrences. Here we present 4 illustrative cases together with a discussion of the underlying pathology. Whereas the mechanisms are usually quite well understood, the management of further anticoagulation after a breakthrough event is based on minimal or no clinical trial evidence.

Novel perspectives on diagnosis and clinical significance of the post-thrombotic syndrome in children

INTRODUCTION

Given the increase in venous thromboembolic events (VTE) in children, the incidence, diagnosis and management of post thrombotic syndrome (PTS) in children is of increasing interest. Current challenges facing clinicians caring for children with VTE is the limited evidence of the long-term outcomes for this cohort; specifically the significance and potential functional impairment associated with PTS.

AREAS COVERED

This paper reviews the current evidence to elucidate the risk factors for PTS in children, methods for diagnosis and management of PTS in children (aged less than 18 years). Medline, Cinahl and PsycINFO database searches were undertaken using key search terms. Priority areas in need of further research are highlighted. Expert commentary: The two paediatric PTS assessment tools currently in use have been acknowledged to overcall the incidence of mild PTS in children. A PTS tool's ability to distinguish between clinically significant PTS and mild PTS is crucial. Variation in how PTS has been reported in children across the literature suggests that the real incidence of moderate and /or clinically significant PTS in children is unknown. Furthermore, evidence is lacking about the functional impairment experienced by children with clinically significant PTS and what this means for their long-term health.

How We Manage Pediatric Deep Venous Thrombosis

Over the past two decades, the incidence and recognition of venous thromboembolism (VTE) in children has significantly increased, likely as a result of improvements in the medical care of critically ill patients and increased awareness of thrombotic complications among medical providers. Current recommendations for the management of VTE in children are largely based on data from pediatric registries and observational studies, or extrapolated from adult data. The scarcity of high-quality evidence-based recommendations has resulted in marked variations in the management of pediatric VTE among providers. The purpose of this article is to summarize our institutional approach for the management of VTE in children based on available evidence, guidelines, and clinical practice considerations. Therapeutic strategies reviewed in this article include the use of conventional anticoagulants, parenteral targeted anticoagulants, new direct oral anticoagulants, thrombolysis, and mechanical approaches for the management of pediatric VTE.

Post thrombotic syndrome following deep vein thrombosis in paediatric patients

Background Although well characterised in adults, less is known about post-thrombotic syndrome in children. In this review, current knowledge regarding paediatric post-thrombotic syndrome is summarised, with particular emphasis on pathophysiology, aetiology, diagnosis and management. Methods A Medline literature review was performed using search terms 'post thrombotic syndrome', 'post phlebitic syndrome', paediatric and children. Relevant articles were identified and included for summation analysis. Results The incident of paediatric venous thromboembolism is rising. Deep vein thrombosis can cause venous hypertension through a combination of venous reflux, venous obstruction and impairment of the calf muscle pump, leading to development of post-thrombotic syndrome. In children, this is more likely to occur if deep vein thrombosis diagnosis and treatment are delayed, if a higher number of vessels are involved, and if factors such as D-dimer are elevated at diagnosis and throughout treatment. Post-thrombotic syndrome occurs in about 26% of paediatric deep vein thrombosis, though the results of individual studies vary widely. A number of tools exist to diagnose paediatric post-thrombotic syndrome, including the modified Villalta scale and Manco-Johnson instrument. Once post-thrombotic syndrome develops, the mainstay of treatment remains supportive, with little evidence of benefit from pharmacological measures. Conclusion Surgical or interventional treatment is not advised except in exceptional cirumstances, due to variable prognosis of PTS in paediatric populations with rising incidence of paediatric venous thromboembolism, it follows that the prevalence of post-thrombotic syndrome in children may also increase. Evidence-based venous thromboembolism prevention strategies need to be implemented for prevention of deep vein thrombosis, but when it does occur, deep vein thrombosis requires prompt and effective treatment to prevent post-thrombotic syndrome. Optimum treatment strategies for post-thrombotic syndrome require further investigation.

Pediatric Thrombolysis: A Practical Approach

The incidence of pediatric venous thromboembolic disease is increasing in hospitalized children. While the mainstay of treatment of pediatric thrombosis is anticoagulation, reports on the use of systemic thrombolysis, endovascular thrombolysis, and mechanical thrombectomy have steadily been increasing in this population. Thrombolysis is indicated in the setting of life- or limb-threatening thrombosis. Thrombolysis can rapidly improve venous patency thereby quickly ameliorating acute signs and symptoms of thrombosis and may improve long-term outcomes such as postthrombotic syndrome. Systemic and endovascular thrombolysis can result in an increase in minor bleeding in pediatric patients, compared with anticoagulation alone, and major bleeding events are a continued concern. Also, endovascular treatment is invasive and requires technical expertise by interventional radiology or vascular surgery, and such expertise may be lacking at many pediatric centers. The goal of this mini-review is to summarize the current state of knowledge of thrombolysis/thrombectomy techniques, benefits, and challenges in pediatric thrombosis.

Endovascular Management of May-Thurner Syndrome in Adolescents: A Single-Center Experience

PURPOSE

To report a single-center experience in regard to the technique, safety, and clinical outcomes of endovascular therapy for treatment of May-Thurner syndrome (MTS) in adolescent patients.

MATERIALS AND METHODS

A retrospective review identified 10 patients (6 female; mean age, 16 y; range, 12-18 y; mean weight, 73 kg; range, 50-116 kg) treated by endovascular therapy for MTS from 1998 to 2015. Clinical presentations consisted of acute thrombotic MTS (n = 6) and nonthrombotic MTS (n = 4). Catheter-directed thrombolysis was performed in all cases of thrombosis. Venoplasty and stent placement were performed in all cases. Self-expanding stents 12-16 mm in diameter and 4-9 cm in length were deployed.

RESULTS

No major periprocedural complications were observed. Median follow-up was 32 months (range, 6-109 mo). Primary and secondary patency rates were 79% and 100% at 12 months and 79% and 89% at 36 months, respectively. In a single patient with permanent loss of flow in the treated segment, multiple risk factors for thrombosis were identified. Rates of posttreatment symptoms were 0% by Villalta score and 60% (n = 6; mild symptoms) by modified Villalta score at the last clinical follow-up.

CONCLUSIONS

Endovascular therapy for the treatment of MTS in our adolescent cohort was safe and effective in relieving venous obstruction. Stent placement in patients with underlying thrombophilic disorders is associated with loss of secondary patency, suggesting the need for further consideration in this population.

Postthrombotic syndrome and other outcomes of lower extremity deep vein thrombosis in children

The frequency of PTS, PE, and DVT recurrence was higher in children with Non-LR DVT than in children with LR DVT. Thrombus resolution, DVT triggering event, and sex were predictors of LE PTS in children.

Ultrasound Assisted Endovascular Thrombolysis in Adolescents: 2 Case Reports

Descending iliofemoral thrombosis in children is a rare event. Anticoagulation therapy with low-molecular-weight-heparin is standard of care. However, patency cannot be achieved in all cases, increasing the risk for rethrombosis and postthrombotic syndrome. To reduce the risk of venous valve failure in adults, local catheter-directed thrombolysis is used to reopen vessels. Two adolescent girls (17 and 15 years old) presented with acute descending iliofemoral thrombosis of the left common iliac, external, and common femoral veins. Anticoagulation with enoxaparin was started until insertion of an EkoSonic Mach 4e catheter for ultrasound-assisted local thrombolysis with recombinant tissue plasminogen activator and administration of unfractionated heparin. Success was monitored by increases in D-dimer levels and ultrasound findings. After 24 hours respectively 48 hours, complete recanalization was obtained. No complication occurred except minimal local bleeding. Screening for hereditary thrombophilia revealed a heterozygous antithrombin mutation in 1 girl (ie, the 15-year-old). May-Thurner syndrome was identified in both girls, necessitating stenting of the left common iliac veins and continuation of anticoagulation therapy with enoxaparin and acetylsalicylic acid. No rethrombosis or complications occurred during the follow-up period. Ultrasound-assisted catheter-directed local thrombolysis with the EkoSonic Mach 4e system was effective in achieving immediate recanalization of the occluded veins and should be considered in children experiencing descending iliofemoral thrombosis. The fast recanalization might reduce the incidence of postthrombotic syndrome. May-Thurner syndrome is regularly found in these patients, and if present, requires stenting of the common iliac vein to avoid early reocclusion. However, long-term patency of iliac vein stenting in children remains to be examined.

[Haemostatic disorders in children]

Haemorrhagic and thrombotic events occur in both children and adults. The underlying causes are congenital or acquired disorders. In contrast to haemorrhagic disorders, inherited thrombotic disorders nearly exclusively in association with additional external risk factors lead to thrombotic events predominantly during the newborn period and adolescence. It is necessary to be aware of age-specific properties of coagulation in order to correctly interpret clinical and laboratory findings and to provide optimal care for children with haemorrhagic and thrombotic complications.

Guidance for the use of thrombolytic therapy for the treatment of venous thromboembolism

Patients with venous thromboembolism (VTE) are prone to the development of both short-term and long-term complications that can substantially affect their functional capacity and quality of life. Patients with deep vein thrombosis (DVT) often develop recurrent VTE or the post-thrombotic syndrome, whereas patients with pulmonary embolism (PE) can develop long-term symptoms and functional limitations along a broad spectrum extending to full-blown chronic thromboembolic pulmonary hypertension. Clinicians who care for patients showing severe clinical manifestations of DVT and PE are often faced with challenging decisions concerning whether and how to escalate to more aggressive treatments such as those involving the use of thrombolytic drugs. The purpose of this chapter is to provide guidance on how best to individualize care to these patients.

Outcomes in children with deep vein thrombosis managed with percutaneous endovascular thrombolysis

BACKGROUND

Our center has developed a multidisciplinary approach to percutaneous endovascular thrombolysis with the goal of improving outcomes in children with thrombosis. There is little data describing the safety and efficacy of endovascular thrombolysis and the frequency of post-thrombotic syndrome after thrombolysis in children.

OBJECTIVE

Retrospective analysis of children undergoing percutaneous endovascular thrombolysis to determine (1) the safety and efficacy of this procedure and (2) the frequency of the diagnosis of post-thrombotic syndrome after thrombolysis.

MATERIALS AND METHODS

We reviewed the medical and imaging databases for children who underwent percutaneous endovascular thrombolysis for deep venous thrombosis (DVT) between November 2008 and June 2013 at our institution. Demographic data were reviewed for the technical success and complications of thrombolysis and the last assigned post-thrombotic syndrome score using standardized scoring tools.

RESULTS

Forty-one children ages 3 months to 21 years (median age: 15 years; 44% male) underwent percutaneous endovascular thrombolysis between November 2008 and June 2013. Upper extremity DVT occurred in 13 patients (32%); lower extremity DVT occurred in 28 patients (68%). All 41 patients received thrombolysis grading; 90% of those patients achieved greater than 50% thrombus lysis. Twenty-eight patients received formal post-thrombotic syndrome scoring and 4 (14%) met diagnostic criteria for post-thrombotic syndrome. One major bleeding episode and one pulmonary embolism occurred with no long-term sequelae.

CONCLUSION

Endovascular thrombolysis for DVT in children is safe, effective at thrombus removal and may reduce the incidence of post-thrombotic syndrome. Randomized or larger clinical trials would be needed to determine the long-term benefits of endovascular thrombolysis.

Pharmacomechanical thrombectomy and catheter-directed thrombolysis of acute lower extremity deep venous thrombosis in a 9-year-old boy with inferior vena cava atresia

Lower extremity deep venous thrombosis (DVT) is uncommon in the pediatric population, but it can be associated with severe symptoms and potential long-term morbidity secondary to post-thrombotic syndrome. Inferior vena cava (IVC) atresia can predispose a patient to the development of extremity DVT. There is no clear consensus on optimal management of extensive extremity DVT in pediatric patients, especially in patients with IVC anomalies. We report a case of iliofemoral DVT in a 9-year-old boy with IVC atresia and presumed protein S deficiency that was treated successfully using pharmacomechanical thrombectomy and catheter-directed thrombolysis. He was maintained on long-term anticoagulation and remained symptom free at 6 months' follow-up.

Endovascular venous thrombolysis in children younger than 24 months

PURPOSE

To evaluate the technical feasibility and safety of percutaneous endovascular thrombolysis for extremity deep venous thrombosis (DVT) in children < 24 months old.

MATERIALS AND METHODS

A retrospective chart review of a clinical and imaging database was performed for pediatric patients who underwent endovascular therapy for DVT between January 2010 and July 2013. Indications, techniques, technical and clinical success, and complications were reviewed. Techniques for thrombolysis included catheter-directed therapy (CDT) using alteplase infusion via a multi-side hole catheter, mechanical thrombectomy, and angioplasty. Short-term outcomes were assessed using surgical and imaging follow-up examinations for patency of the targeted vessel. Patients included 11 children (mean age, 9 mo; range, 3 wk-23 mo) who consecutively underwent endovascular thrombolysis for upper extremity (n = 6) or lower extremity (n = 5) DVT. The most common indication was preservation of venous access for future cardiac surgery or medical therapy.

RESULTS

The most common risk factor was the presence of a central venous catheter (10 of 11 patients). All patients with upper extremity DVT had congenital heart disease. CDT and angioplasty were performed in all patients. Venous patency was established in all patients. A grade III (95%-100%) thrombolysis response was achieved in seven patients, and a grade II (50%-95%) thrombolysis response was achieved in four patients. A major complication of pulmonary embolism occurred in one patient with upper extremity thrombolysis and was managed by intravenous systemic alteplase and heparin. No recurrence of thrombosis was found on average follow-up of 11.8 months (range, 1-41 mo).

CONCLUSIONS

Percutaneous endovascular thrombolysis for extremity DVT is safe and technically feasible in children < 24 months old.

Antithrombotic therapies: anticoagulation and thrombolysis

Pediatric deep vein thrombosis is an increasingly recognized phenomenon, especially with advances in treatment and supportive care of critically ill children and with better diagnostic capabilities. High-quality evidence and uniform management guidelines for antithrombotic treatment, particularly thrombolytic therapy, remain limited. Optimal dosing, intensity and duration strategies for anticoagulation as well as thrombolytic regimens that maximize efficacy and safety need to be determined through well-designed clinical trials using use of a risk-stratified approach.

Developing a pediatric endovascular thrombolysis program: a single-center experience

Deep venous thrombosis (DVT) is being increasingly recognized as a significant issue in children. Despite the low incidence of DVT, the risks of pulmonary embolism and death in children are significant. Post-thrombotic syndrome, a syndrome of chronic venous insufficiency, can have long-term adverse consequences in children and adolescents. Adult studies have shown that catheter-directed therapy can reduce the incidence of post-thrombotic syndrome. Safety of catheter-directed therapy in adolescents has also been demonstrated. These reasons compelled us to institute a pediatric endovascular thrombolysis program at our institute for management of pediatric DVT. We describe the process of developing a multi-disciplinary thrombolysis program involving interventional radiology (pediatric and adult), pediatric hematology, critical care, anesthesia and vascular surgery, and describe the role of each specialty in the development of the program. We also describe our experience with patient selection, endovascular therapy procedure, pre-, intra- and post-procedure monitoring, and follow-up management for endovascular therapy for DVT.