title: Deep vein thrombosis of lower extremity: direct intraclot injection of alteplase once daily with systemic anticoagulation--results of pilot study.
abstract: OBJECTIVE
  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).
  
  
  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 throughout 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Diagnostic Radiology, Warren G. Magnuson Clinical Center, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA. rchang@cc.nih.gov
authors.forename: Richard
authors.initials: R
authors.lastname: Chang
authors.forename: Clara C
authors.initials: CC
authors.lastname: Chen
authors.forename: Anthony
authors.initials: A
authors.lastname: Kam
authors.forename: Edie
authors.initials: E
authors.lastname: Mao
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Shawker
authors.forename: McDonald K
authors.initials: MK
authors.lastname: Horne
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage; D006801:Humans; D015552:Injections, Intralesional; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D010959:Tissue Plasminogen Activator / Q000008:administration & dosage*; D016896:Treatment Outcome; D020246:Venous Thrombosis / Q000188:drug therapy*
chemical_list: D000925:Anticoagulants; D005343:Fibrinolytic Agents; D010959:Tissue Plasminogen Activator