A novel catheter system for totally implantable intravenous drug therapy: assessment of catheter function and patency with trepostinil therapy

Background: Catheter failure, either due to dislodgment, occlusion or infection is the leading complication of chronic intravenous drug therapy. Better drug delivery techniques are required to advance life saving therapies that require this delivery method. This study evaluated the chronic performance of a fully implantable drug delivery system that incorporates a novel intravenous catheter. The system was designed to reduce complications associated with intravascular drug delivery including catheter occlusion, breakage, migration, and infection. Methods: Twelve canines were implanted with a novel central venous catheter (Model 10642; Medtronic, Minneapolis, MN) connected to a totally implanted programmable drug pump (Model 8637 SynchroMed III, Medtronic). The drug delivery systems infused saline (n=6) or treprostinil (n=6) (Remodulin((R)); United Therapeutics, Research Triangle Park, NC) for either 12 or 26 weeks at a continuous flow rate of 540 mu L/day. Catheter performance was assessed at 0 (implant), 2, 4, 8, 12, 16, 20, and 24 weeks by quantifying delivery pressure, delivery volume and steady state Treprostinil concentrations. Results: All catheters remained patent and free of complications for the duration of the study. Analysis of pressure waveforms during bolus delivery showed low and unchanged catheter resistance throughout the study. Measurement of pump delivery volume accuracy showed that the delivered volume was statistically similar to the calculated delivery (product of flow rate and elapsed time). Measurement of plasma treprostinil levels showed stable concentrations over the study period. There were no catheter dislodgments or breakage. Pathology showed all catheters free from fibrosis and thrombus and minimal changes to the vascular endothelium. Conclusions: The Model 10642 vascular catheter along with the SynchroMed II implantable drug delivery system showed promising performance in a chronic animal model.