Deep vein thrombosis of lower extremity: Direct intraclot injection of alteplase once daily with systemic anticoagulation - Results of pilot study

Purpose: To prospectively evaluate the outcome of patients with acute deep vein thrombosis (DVT) of the lower extremity treated with "lacing" of the thrombus with alteplase (recombinant tissue plasminogen activator, or rTPA). Materials and Methods: This HIPAA-compliant study was approved by the Institutional Review Board of the National Heart, Lung, and Blood Institute and was funded by the National Institutes of Health. After giving written consent, 20 patients with first-onset acute DVT were treated with direct intraclot lacing of the thrombus with alteplase (maximum daily dose, 50 mg per leg per day; maximum of four treatments) and full systemic anticoagulation. Alteplase was chosen because its high fibrin affinity obviates continuous infusion of this thrombolytic agent. Ventilation-perfusion (V/Q) scans were performed for evaluation of embolic risks, and clinical and imaging examinations were supplemented with pharmacokinetic studies to enable further assessment of treatment outcomes. Results: The 20 patients included 13 men and seven women aged 18-79 years. Antegrade blood flow was restored through-out the deep venous system in 16 patients (80%) during thrombolytic therapy, with complete resolution of symptoms in 18 patients (90%) after 6 months of anticoagulation. Pharmacokinetic studies showed rapid clearance of circulating alteplase and recovery of plasminogen activator inhibitor-1 levels within 2 hours after termination of alteplase treatment. V/Q scans revealed a 40% incidence of pulmonary embolism before treatment and a 15% incidence of asymptomatic pulmonary embolism during thrombolytic therapy. There were no cases of clinically important pulmonary embolism or serious bleeding during thrombolytic therapy. During a mean follow-up period of 3.4 years, no patient developed a postthrombotic syndrome or recurrent thromboembolism. Conclusion: Intraclot injection or lacing of the thrombus with a fibrin-binding thrombolytic agent such as alteplase is an alternative to continuous-infusion thrombolytic regimens and minimizes the duration of systemic exposure to thrombolytic agents.