Thrombus age is ideally measured by history or MRV prior to thrombus removal

Time-dependent ultrastructural changes during venous thrombogenesis and thrombus resolution

BACKGROUND

Deep vein thrombosis is a common vascular event that can result in debilitating morbidity and even death due to pulmonary embolism. Clinically, patients with faster resolution of a venous thrombus have improved prognosis, but the detailed structural information regarding changes that occur in a resolving thrombus over time is lacking.

OBJECTIVES

To define the spatial-morphologic characteristics of venous thrombus formation, propagation, and resolution at the submicron level over time.

METHODS

Using a murine model of stasis-induced deep vein thrombosis along with scanning electron microscopy and immunohistology, we determine the specific structural, compositional, and morphologic characteristics of venous thrombi formed after 4 days and identify the changes that take place during resolution by day 7. Comparison is made with the structure and composition of venous thrombi formed in mice genetically deficient in plasminogen activator inhibitor type 1.

RESULTS

As venous thrombus resolution progresses, fibrin exists in different structural forms, and there are dynamic cellular changes in the compositions of leukocytes, platelet aggregates, and red blood cells. Intrathrombus microvesicles are present that are not evident by histology, and red blood cells in the form of polyhedrocytes are an indicator of clot contraction. Structural evidence of fibrinolysis is observed early during thrombogenesis and is accelerated by plasminogen activator inhibitor type 1 deficiency.

CONCLUSION

The results reveal unique, detailed ultrastructural and compositional insights along with documentation of the dynamic changes that occur during accelerated resolution that are not evident by standard pathologic procedures and can be applied to inform diagnosis and effectiveness of thrombolytic treatments to improve patient outcomes.

Clinical impact of assessing thrombus age using magnetic resonance venography prior to catheter-directed thrombolysis

Objectives

Magnetic resonance venography (MRV) is underutilized in the evaluation of thrombus properties prior to endovascular treatment but may improve procedural outcomes. We therefore investigated the clinical impact of using a dedicated MRV scoring system to assess thrombus characteristics prior to endovascular intervention for iliofemoral deep vein thrombosis (DVT).

Methods

This is a post hoc analysis of data from the CAVA trial (Clinicaltrials.gov:NCT00970619). MRV studies of patients receiving ultrasound-accelerated catheter-directed thrombolysis (CDT) for iliofemoral DVT were reviewed. Thrombus age-related imaging characteristics were scored and translated into an overall score (acute, subacute, or old). MRV scores were compared to patient-reported complaints. MRV-scored groups were compared for CDT duration and success rate.

Results

Fifty-six patients (29 men; age 50.8 ± 16.4 years) were included. Using MRV, 27 thrombi were classified acute, 17 subacute, and 12 old. Based on patient-reported complaints, 11 (91.7%) of these old thrombi would have been categorized acute or subacute, and one (3.7%) of the acute thrombi as old. Average duration of CDT to > 90% restored patency differed significantly between groups (p < 0.0001): average duration was 23 h for acute thromboses (range: 19–25), 43 h for subacute (range: 41–62), and 85 h for old thromboses (range: 74–96). CDT was almost eleven times more successful in thromboses characterized as acute and subacute compared to old thromboses (OR: 10.7; 95% CI 2.1–55.5).

Conclusion

A dedicated MRV scoring system can safely discriminate between acute, subacute, and old thromboses. MRV-based selection is predictive of procedural duration and success rate and can help avoid unnecessary complications.

Key Points

• Thrombus age, characterized by MRV as acute, subacute, and old, can predict CDT duration and probability of success.

• Accurate pre-interventional MRV-based thrombus aging has the potential to facilitate identification of eligible patients and may thus prevent CDT-related complications.

Intraoperative Imaging and Image Fusion for Venous Interventions

Advanced imaging for intraoperative evaluation of venous pathologies has played an increasingly significant role in this era of evolving minimally invasive surgical and interventional therapies. The evolution of dedicated venous stents and other novel interventional devices has mandated the need for advanced imaging tools to optimize safe and accurate device deployment. Most venous interventions are typically performed using a combination of standard 2-dimensional (2D) fluoroscopy, digital-subtraction angiography, and intravascular ultrasound imaging techniques. Latest generation computer tomography (CT) and magnetic resonance imaging (MRI) scanners have been shown to provide high-resolution 3D and 4D information about venous vasculature. In addition to morphological imaging, novel MRI techniques such as 3D time-resolved MR venography and 4D flow sequences can provide quantitative information and help visualize intricate flow patterns to better understand complex venous pathologies. Moreover, the high-fidelity information from multiple imaging techniques can be integrated using image fusion to overcome the limitations of current intraoperative imaging techniques. For example, the limitations of standard 2D fluoroscopy and luminal angiography can be compensated for by perivascular and soft-tissue information from MRI during complex venous interventions using image fusion techniques. Intraoperative dynamic evaluation of devices such as venous stents and real-time understanding of changes in flow patterns during venous interventions may be routinely available in future interventional suites with integrated multimodality CT or MR imaging capabilities. The purpose of this review is to discuss the outlook for intraoperative imaging and multimodality image fusion techniques and highlight their value during complex venous interventions.

Safety and Efficacy of Catheter Direct Thrombolysis in Management of Acute Iliofemoral Deep Vein Thrombosis: A Systematic Review

Purpose

Catheter direct thrombolysis (CDT) has been shown to be an effective treatment for deep venous thrombosis. The objective of the review is to improve safety and efficacy of the CDT by using ward based protocol, better able to predict complications and treatment outcome through monitoring of haemostatic parameters and clinical observation during thrombolysis procedure.

Materials and Methods

MEDLINE, EMBASE, CENTRAL and Web of Science were searched for all articles on deep venous thrombosis, thrombolysis and correlations of clinical events (bleeding, successful thrombolysis) during thrombolysis with hemostatic parameters to March 2016. The risk of bias in included studies was assessed by Cochrane Collaboration’s tool and Cochrane Risk of Bias Assessment Tool: for Non-Randomized Studies of Interventions.

Results

Twenty-four studies were included in the review and we found that improving safety and efficacy of CDT by using ward based protocol depending on eight factors; strict patient selection criteria, types of fibrinolytic drugs, mode of fibrinolytic drug injection, biochemical markers monitoring (fibrinogen, D-dimer, activated partial thromboplastin time, plasminogen activator inhibitor-1), timing of intervention, usage of intermittent pneumatic calf, ward monitoring and thrombolysis imaging assessment (intravascular ultrasound). These factors may help to improve safety and efficacy by reducing total thrombolytic drug dosage and at the same time ensure successful lysis. There is a marked lack of randomized controlled trials discussing the safety and efficacy of catheter direct thrombolysis.

Conclusion

CDT can be performed safely and efficiently in clinical ward, providing that careful nursing, biochemical monitoring, proper selection and mode of infusion of fibrinolytic drugs, usage of Intermittent pneumatic calf and adequate thrombolysis imaging assessment are ensured.