Ultrasound-enhanced Thrombolysis Versus Standard Catheter Directed Thrombolysis for Ilio-femoral Deep Vein Thrombosis

Overview

Patients with deep vein thrombosis (DVT) of the ilio-femoral veins have increased risk for developing post-thrombotic syndrome (PTS) and recurrent venous thromboembolism compared to more distal DVT. There's evidence that the early removal of the obstructing thrombus by catheter directed thrombolysis (CDT) reduces the risk of developing a PTS, and a higher degree of thrombolysis is associated with lower incidence of PTS, better quality of life and lower risk of recurrent venous thromboembolism. A further development is ultrasound-enhanced thrombolysis combining CDT with a sophisticated catheter system that employs high-frequency, low-dose ultrasound. In vitro experiments showed that adding ultrasound to thrombolytic drugs accelerates thrombolysis while Ultrasound exposure alone results in no thrombolysis, however the superiority of ultrasound-enhanced thrombolysis over standard CDT has never been formally assessed in vivo. The hypothesis for this study is that ultrasound-enhanced thrombolysis reaches a higher degree of thrombolysis than standard CDT in patients with symptomatic ilio-femoral DVT.

Background Deep vein thrombosis (DVT) is a public health problem with an annual incidence of 1 per 1000. Besides the acute risk of potentially fatal pulmonary embolism or phlegmasia cerulea dolens, these patients are at increased risk of recurrent venous thromboembolism, and in the long term 20-40% of them develop a post-thrombotic syndrome (PTS). PTS mainly develops in patients with DVT affecting the ilio-femoral veins, adversely affects the quality of life and causes important health care costs to the society. There's evidence that the early removal of the obstructing thrombus reduces the risk of developing a PTS, and a higher degree of thrombolysis is associated with lower incidence of PTS, better quality of life and lower risk of recurrent venous thromboembolism. Therefore, in addition to standard anticoagulation therapy, the latest international guidelines recommend catheter-directed thrombolysis (CDT) as first-line treatment for patients with ilio-femoral DVT and low bleeding risk. CDT refers to the infusion of thrombolytic drugs directly into the thrombus via a multisidehole catheter which is embedded in the thrombus using imaging guidance. A further development is ultrasound-enhanced thrombolysis combining CDT with a sophisticated catheter system that employs high-frequency, low-dose ultrasound. In vitro experiments showed that adding Ultrasound to thrombolytic drugs accelerates thrombolysis while Ultrasound exposure alone results in no thrombolysis. Although ultrasound-enhanced thrombolysis is now widely used to treat ilio-femoral DVT or high-risk pulmonary embolism, it is currently not known if this technique is superior to standard CDT. Objective To determine if the addition of intravascular high-frequency/low-dose ultrasound to standard CDT increases the percentage of clot lysis compared to CDT alone after treatment duration of 15 hours in patients with symptomatic ilio-femoral DVT and low bleeding risk Methods Study design: open-label (with blinding of data-analyzing physicians), randomized, controlled, single center clinical trial with a follow-up period of 12 months. Subjects: total of 20 patients (10 in each study group) of 18-75 years of age with acute, symptomatic, objectively confirmed ilio-femoral DVT and a low bleeding risk. Intervention: CDT using the EkoSonic Endovascular System with (CDT+US group) or without (CDT-US group) intravascular high-frequency, low-power ultrasound for 15 hours.