Reexamining the Open-Vein Hypothesis for Acute Deep Venous Thrombosis

Early Thrombus Removal for Acute Lower Extremity Deep Vein Thrombosis: Update on Inclusion, Technical Aspects, and Postprocedural Management

Acute lower extremity deep vein thrombosis (DVT) is a common disorder with significant associated morbidity, including pain and swelling, as well as the risk of pulmonary embolism (PE), recurrent venous thromboembolism (VTE) and chronic debilitating post-thrombotic syndrome (PTS). Anticoagulation is standard of care for DVT treatment. It assists in reducing thrombus progression and the occurrence of PE, but incomplete DVT resolution increases the risk of recurrent VTE, valvular insufficiency, and PTS. Endovascular DVT interventions, such as catheter-directed thrombolysis, pharmacomechanical thrombectomy, and large-bore mechanical thrombectomy offer an alternative therapeutic strategy for DVT management. This paper will discuss technical factors and current issues when performing lower extremity DVT interventions including patient selection, anticoagulation, choice of device for endovascular thrombus removal, adjunctive techniques, and venous stent management.Level of Evidence: No level of evidence for: review articles, basic science, laboratory investigations, and experimental study articles.

Sonothrombolysis Using Microfluidically Produced Microbubbles in a Murine Model of Deep Vein Thrombosis

The need for safe and effective methods to manage deep vein thrombosis (DVT), given the risks associated with anticoagulants and thrombolytic agents, motivated research into innovative approaches to resolve blood clots. In response to this challenge, sonothrombolysis is being explored as a technique that combines microbubbles, ultrasound, and thrombolytic agents to facilitate the aggressive dissolution of thrombi. Prior studies have indicated that relatively large microbubbles accelerate the dissolution process, either in an in vitro or an arterial model. However, sonothrombolysis using large microbubbles must be evaluated in venous thromboembolism diseases, where blood flow velocity is not comparable. In this study, the efficacy of sonothrombolysis was validated in a murine model of pre-existing DVT. During therapy, microfluidically produced microbubbles of 18 μm diameter and recombinant tissue plasminogen activator (rt-PA) were administered through a tail vein catheter for 30 min, while ultrasound was applied to the abdominal region of the mice. Three-dimensional ultrasound scans were performed before and after therapy for quantification. The residual volume of the thrombi was 20% in animals post sonothrombolysis versus 52% without therapy ( p = 0.012 < 0.05 ), indicating a significant reduction in DVT volume. Histological analysis of tissue sections confirmed a reduction in DVT volume post-therapy. Therefore, large microbubbles generated from a microfluidic device show promise in ultrasound-assisted therapy to address concerns related to venous thromboembolism.

Percutaneous Transluminal Angioplasty Alleviate Pediatric Postthrombotic Syndrome: A Case Report and Literature Review

PURPOSE

Postthrombotic syndrome (PTS) is one of the long-term sequelae of deep vein thrombosis (DVT), and effective symptom management in pediatric PTS remains a challenge, with interventional therapy rarely explored in this population. We present a successful case of interventional treatment pediatric PTS, resulting in a remarkable amelioration of her symptoms.

CASE REPORT

This case features a 6-year-old girl diagnosed with hyperinsulinemia, leading to a hypoglycemic coma. Following a mini-pancreatic partial pancreatectomy, she required further intensive care in the pediatric intensive care unit. It was during this period that left lower extremity DVT was identified, prompting warfarin anticoagulation therapy. During the anticoagulation period, she had several bleeding events and was switched to anticoagulation with low molecular heparin. One month later, the left common iliac vein and external iliac vein was found to be completely occluded. Over time, she experienced a gradual onset of lower limb swelling and pain, which, after 6 months, was accompanied by perineal edema and venous claudication. As a result, she underwent successful percutaneous transluminal angioplasty. In addition, the anticoagulation regimen was adjusted to rivaroxaban. At the 8-month follow-up, we observed significantly improvement in her postoperative lower extremity swelling and symptoms related to venous occlusion had completely disappeared. Moreover, vascular imaging confirmed improvement in stenosis and uninterrupted blood flow.

CONCLUSIONS

In our review of pediatric PTS studies, we observed limited options to alleviate symptoms, and interventional treatments have not been reported. Our case study, demonstrating the safe and effective use of percutaneous transluminal angioplasty, helps to illuminate this area and alleviate pediatric PTS symptoms.

CLINICAL IMPACT

This case validates the efficacy and safety of using percutaneous transluminal angioplasty (PTA) for the treatment of postthrombotic syndrome (PTS) in pediatric patients. This interventional approach offers significant symptomatic relief and improves quality of life, especially in cases where traditional anticoagulation therapies fail or lead to complications. The successful case presented emphasizes the necessity of considering endovascular interventions for children with moderate to severe PTS, particularly when conservative management is ineffective. This research underscores the potential for PTA to be adopted in clinical practice, offering a promising new approach for managing pediatric PTS.

Antithrombotic management of patients with deep vein thrombosis and venous stents: an international registry

BACKGROUND

In patients with acute deep vein thrombosis (DVT) treated with catheter-based thrombolysis and venous stenting, poststenting anticoagulant management is uncertain.

OBJECTIVES

To determine the type and duration of antithrombotic therapy used in patients who have received venous stents for treatment of acute lower extremity DVT.

METHODS

We created an international registry of patients with leg DVT from 2005 to 2019 who received venous stents as part of their acute management. We collected data on baseline clinical characteristics and pre-venous and post-venous stent antithrombotic therapy.

RESULTS

We studied 173 patients with venous stents: 101 (58%) were aged ≤50 years, 105 (61%) were female, and 128 (74%) had risk factors for thrombotic disease. DVT was iliofemoral in 150 (87%) patients, and catheter-based treatment was given within 7 days of diagnosis in 92 (53%) patients. After venous stenting, 109 (63%) patients received anticoagulant-only therapy with a direct oral anticoagulant (29%), warfarin (22%), or low-molecular-weight heparin (10%), and 59 (34%) received anticoagulant-antiplatelet therapy. In patients taking anticoagulant-only therapy, 29% received indefinite treatment; in patients on anticoagulant-antiplatelet therapy, 19% received indefinite treatment. Factors associated with combined anticoagulant-antiplatelet therapy vs anticoagulant-only therapy were use of thrombolytic, thrombectomy, and aspiration interventions (odds ratio [OR], 5.11; 95% CI, 1.45-18.05); use of balloon angioplasty (OR, 2.62; 95% CI, 1.20-5.76); and immediate stent restenosis (OR, 7.2; 95% CI, 1.45-5.89).

CONCLUSION

Anticoagulant therapy without concomitant antiplatelet therapy appears to be the most common antithrombotic strategy in patients with DVT and venous stenting. More research is needed to determine outcomes of venous stenting in relation to antithrombotic therapy.

Catheter-Directed Interventions for the Treatment of Lower Extremity Deep Vein Thrombosis

Lower extremity deep vein thrombosis (DVT) leads to significant morbidity including pain, swelling, and difficulty walking in the affected limb. If left untreated, DVT increases the risk of pulmonary embolism (PE), recurrent venous thromboembolism (VTE), and post thrombotic syndrome (PTS). The objective of this review was to identify catheter-directed interventions and their success rates for the treatment of lower extremity DVT. A comprehensive search of current and emerging catheter-directed interventions for lower extremity DVT treatment was conducted in PubMed and Google Scholar. Clinical trials, retrospective and prospective observational studies, and case reports were identified to classify percutaneous mechanical thrombectomy (PMT), catheter-directed thrombolysis (CDT), and pharmacomechanical CDT (PCDT) devices based on their mechanism of action and indication of use. Catheter-directed interventions such as PMT, CDT, and PCDT offer an alternative therapeutic strategy for DVT management, particularly in patients with limb-threatening conditions and absolute contraindications to anticoagulants. Currently, there are limited guidelines for the use of mechanical and pharmacomechanical devices because of the lack of clinical evidence available for their use in treatment. Future studies are required to determine the short and long-term effects of using catheter-directed interventions as well as their effectiveness in treating acute versus subacute and chronic DVT.

Endovascular Management of Acute Iliofemoral Deep Vein Thrombosis

Lower extremity deep vein thrombosis (DVT) is frequently encountered in clinical practice. Postthrombotic syndrome (PTS) is a common sequela of DVT and encompasses a wide variety of symptoms, including severe pain, edema, and ulceration, all of which may contribute to a negative impact on quality of life. Studies have demonstrated that acute thrombosis of the iliofemoral venous segment is correlated with high rates of PTS, increased severity of symptoms, and high rates of thrombus recurrence, despite patients receiving treatment with standard-of-care anticoagulation therapy. Endovascular interventions, including catheter-directed thrombolysis, pharmacomechanical thrombectomy, and mechanical thrombectomy, have generated significant interest as a method for reduction of short-term symptom severity and potential reduction of downstream PTS severity. While there is high-quality evidence evaluating the role of catheter-directed and pharmacomechanical thrombectomy for acute iliofemoral DVT, newer mechanical-only devices that utilize thrombectomy without fibrinolytic medication are less studied. Currently, there are limited data evaluating the efficacy and safety of these treatment modalities, although investigations are ongoing.

Necroptosis Plays a Crucial Role in Vascular Injury during DVT and Is Enhanced by IL-17B

Background. This study investigated whether vascular endothelial necroptosis is involved in deep vein thrombosis (DVT) and how IL-17B facilitates necroptosis signaling. Methods. The DVT mouse model was induced by ligation of the IVC. The cross-sectional area of thrombus increases and the thrombus occupied the entire venous lumen at 48 h after ligation. Meanwhile, the increased expression of p-RIP3/RIP3 was most pronounced at 48 h after ligation, and the p-MLKL/MLKL peaked at 72 h. Results. Based on Illumina sequencing and KEGG pathway analyses, the activated RIP3/MLKL is associated with increased IL-17B. With thrombus formation, IL-17B was upregulated and enhanced the expression of RIP3 and MLKL in the IVC wall, as well as their phosphorylation levels (all $P<0.05$ , the comparison group consisted of the control group, DVT group, DVT/IL-17B group, and DVT/anti-IL-17B group). The p-RIP3/RIP3 and p-MLKL/MLKL ratios were reduced by anti-IL-17B. Similarly, the weight and cross-sectional area of the thrombi were increased by IL-17B and decreased by the IL-17B antibody. IL-17B had a smaller effect on thrombosis in knockout mice compared with WT mice. In vitro, the IL-17B protein expression and the level of RIP3 and MLKL phosphorylation increased high in the OGD cells, accompanied by increased expression of IL-6 and TNF-α. IL-17B enhanced the expression of IL-6 and TNF-α but had little effect on the IL-6 and TNF-α after transfected with siRIP3 or siMLKL. Similarly, the plasma IL-17B, IL-6, and TNF-α were significantly increased after thrombosis in WT mice, and enhanced by IL-17B. But IL-17B did not increase the plasma IL-6 and TNF-α in knockout mice. Conclusions. In conclusion, those results suggest that vascular endothelial necroptosis plays a crucial role in vascular injury and IL-17B could enhance the necroptosis pathway.

Venous Thromboembolism for the Practicing Cardiologist

Venous thromboembolism (VTE), encompassing pulmonary embolism (PE) and deep vein thrombosis (DVT), is encountered commonly. Acute PE may present as a high-risk cardiovascular emergency, and acute DVT can cause acute and chronic vascular complications. The goal of this review is to ensure that cardiologists are comfortable managing VTE-including risk stratification, anticoagulation therapy, and familiarity with primary reperfusion therapy. Clinical assessment and determination of degree of right ventricular dysfunction are critical in initial risk stratification of PE and determination of parenteral versus oral anticoagulation therapy. Direct oral anticoagulants have emerged as preferred first-line oral anticoagulation strategy in VTE scenarios.

Endovascular Therapy for the Management of Acute Ilio-femoral Deep Vein Thrombosis

Ilio-femoral deep vein thrombosis (DVT) has a high rate of long-term morbidity in the form of the postthrombotic syndrome (PTS). Therefore, management of acute thrombosis should not only focus on the prevention of acute complications such as propagation or embolisation of the initial clot but also on preventing recurrent thrombosis and PTS. Contemporary catheter-based treatments of deep vein thrombosis have proven to be safe and effective in selected patients. Current guidelines recommend medical therapy with anticoagulation alone for all but the most severe, limb-threatening thrombosis. They additionally allow for consideration of endovascular catheter-based treatment in selected patients with acute proximal ilio-femoral DVT and low risk of bleeding complications to prevent PTS. 

Imaging-guided, catheter-based endovascular therapy has been used in selected patients to alleviate these sequelae, but important questions remain about their optimal use. In this article, we review the available evidence and summarize the rationale for use of catheter-based therapy in specific patient groups with acute iliofemoral DVT.

Time-Restricted Salutary Effects of Blood Flow Restoration on Venous Thrombosis and Vein Wall Injury in Mouse and Human Subjects

BACKGROUND

Up to 50% of patients with proximal deep vein thrombosis (DVT) will develop the postthrombotic syndrome characterized by limb swelling and discomfort, hyperpigmentation, skin ulcers, and impaired quality of life. Although catheter-based interventions enabling the restoration of blood flow (RBF) have demonstrated little benefit on postthrombotic syndrome, the impact on the acuity of the thrombus and mechanisms underlying this finding remain obscure. In experimental and clinical studies, we examined whether RBF has a restricted time window for improving DVT resolution.

METHODS

First, experimental stasis DVT was generated in C57/BL6 mice (n=291) by inferior vena cava ligation. To promote RBF, mice underwent mechanical deligation with or without intravenous recombinant tissue plasminogen activator administered 2 days after deligation. RBF was assessed over time by ultrasonography and intravital microscopy. Resected thrombosed inferior vena cava specimens underwent thrombus and vein wall histological and gene expression assays. Next, in a clinical study, we conducted a post hoc analysis of the ATTRACT (Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis) pharmacomechanical catheter-directed thrombolysis (PCDT) trial (NCT00790335) to assess the effects of PCDT on Venous Insufficiency Epidemiological and Economic Study quality-of-life and Villalta scores for specific symptom-onset-to-randomization timeframes.

RESULTS

Mice that developed RBF by day 4, but not later, exhibited reduced day 8 thrombus burden parameters and reduced day 8 vein wall fibrosis and inflammation, compared with controls. In mice without RBF, recombinant tissue plasminogen activator administered at day 4, but not later, reduced day 8 thrombus burden and vein wall fibrosis. It is notable that, in mice already exhibiting RBF by day 4, recombinant tissue plasminogen activator administration did not further reduce thrombus burden or vein wall fibrosis. In the ATTRACT trial, patients receiving PCDT in an intermediate symptom-onset-to-randomization timeframe of 4 to 8 days demonstrated maximal benefits in Venous Insufficiency Epidemiological and Economic Study quality-of-life and Villalta scores (between-group difference=8.41 and 1.68, respectively, P<0.001 versus patients not receiving PCDT). PCDT did not improve postthrombotic syndrome scores for patients having a symptom-onset-to-randomization time of <4 days or >8 days.

CONCLUSIONS

Taken together, these data illustrate that, within a restricted therapeutic window, RBF improves DVT resolution, and PCDT may improve clinical outcomes. Further studies are warranted to examine the value of time-restricted RBF strategies to reduce postthrombotic syndrome in patients with DVT.

Correlation between Post-Procedure Residual Thrombus and Clinical Outcome in Deep Vein Thrombosis Patients Receiving Pharmacomechanical Thrombolysis in a Multicenter Randomized Trial

PURPOSE

To evaluate relationships between immediate venographic results and clinical outcomes of pharmacomechanical catheter-directed thrombolysis (PCDT).

MATERIALS AND METHODS

Venograms from 317 patients with acute proximal deep vein thrombosis (DVT) who received PCDT in a multicenter randomized trial were reviewed. Quantitative thrombus resolution was assessed by independent readers using a modified Marder scale. The physician operators recorded their visual assessments of thrombus regression and venous flow. These immediate post-procedure results were correlated with patient outcomes at 1, 12, and 24 months.

RESULTS

PCDT produced substantial thrombus removal (P < .001 for pre-PCDT vs. post-PCDT thrombus scores in all segments). At procedure end, spontaneous venous flow was present in 99% of iliofemoral venous segments and in 89% of femoral-popliteal venous segments. For the overall proximal DVT population, and for the femoral-popliteal DVT subgroup, post-PCDT thrombus volume did not correlate with 1-month or 24-month outcomes. For the iliofemoral DVT subgroup, over 1 and 24 months, symptom severity scores were higher (worse), and venous disease-specific quality of life (QOL) scores were lower (worse) in patients with greater post-PCDT thrombus volume, with the difference reaching statistical significance for the 24-month Villalta post-thrombotic syndrome (PTS) severity score (P = .0098). Post-PCDT thrombus volume did not correlate with 12-month valvular reflux.

CONCLUSIONS

PCDT successfully removes thrombus in acute proximal DVT. However, the residual thrombus burden at procedure end does not correlate with the occurrence of PTS during the subsequent 24 months. In iliofemoral DVT, lower residual thrombus burden correlates with reduced PTS severity and possibly also with improved venous QOL and fewer early symptoms.

Catheter Interventions for Acute Deep Venous Thrombosis: Who, When and How

Deep venous thrombosis (DVT) is common and can be a source of morbidity by way of pulmonary embolism and post-thrombotic syndrome. Recent trials have demonstrated both early and late symptomatic benefit in venous thrombolysis and early recanalisation of the iliocaval system of selected patients. Based on the emerging evidence, national societies have published guidelines that recommend early thrombus removal in iliofemoral DVT in patients with low bleeding risk and good life expectancy. In light of these recommendations, endovenous thrombolysis and/or thrombectomy have become more popular among vein specialists. As more venous technology becomes available, surgeons and interventionalists should take pause and ensure their patient selection and treatment algorithms parallel that of existing and emerging evidence. This article summarises current evidence, technology, and the approach used at a high-volume academic centre in treating iliofemoral DVT.

Catheter-Based Therapies and Other Management Strategies for Deep Vein Thrombosis and Post-Thrombotic Syndrome

Acute deep vein thrombosis (DVT) causes substantial short-term and long-term patient morbidity. Medical, lifestyle, and compressive therapies have been investigated for the prevention of pulmonary embolism (PE) and recurrence of venous thromboembolism (VTE). However, patient-centered outcomes such as resolution of presenting DVT symptoms and late occurrence of post-thrombotic syndrome (PTS) have not been prioritized to the same degree. Imaging-guided, catheter-based endovascular therapy has been used in selected patients to alleviate these sequelae, but important questions remain about their optimal use. In this article, we review the available evidence and summarize the rationale for use of catheter-based therapy in specific patient groups.