Cathflo Activase Pediatric Study

Inclusion Criteria: Subjects had to meet the following inclusion criteria to be eligible for study entry: * Less than 17 years of age * Clinically stable * Occlusion of CVAD (including catheters with valves, multiple lumens, umbilical catheters, and implanted ports) * For subjects who weighed \>= 10 kg, inability to withdraw 3 mL of blood from the CVAD * For subjects who weighed \< 10 kg, inability to withdraw 1 mL of blood from the CVAD * Ability to infuse fluids at the volume necessary to instill Cathflo Activase into the CVAD * Written informed consent and assent (if appropriate) provided by parent or legal guardian and compliance with study assessments for the full duration of the study Exclusion Criteria: * Ability to withdraw blood following subject repositioning * CVAD insertion \< 48 hours prior to enrollment * Selected study catheter implanted specifically for hemodialysis * Evidence of mechanical, non-thrombotic occlusion of the CVAD (e.g., kink in the CVAD or suture constricting the catheter) * Previous enrollment in this study * Use of fibrinolytic agent (e.g., alteplase, reteplase, tenecteplase, urokinase, streptokinase) within 24 hours of enrollment * At high risk for bleeding events, embolic complications (i.e., recent pulmonary embolism, deep vein thrombosis, endarterectomy, clinically significant right-to-left shunt) in the opinion of the investigator, or with known condition for which bleeding constituted a significant hazard * Known hypersensitivity to alteplase or any component of the formulation