There are numerous examples of catheters and other implantable medical devices that are placed into a patient's vasculature for prolonged periods of time, such as central venous catheters (“CVCs”), implantable ports (“Ports”), dialysis catheters and peripherally-inserted central catheters (“PICCs”). These devices may be used to deliver therapeutic agents and other fluids to patients over numerous weeks.
Inherent with the use of medical devices that are placed into a patient's vasculature or other blood-containing environments is the aggregation of platelets on the device surface, thus leading to a risk of thrombus formation, which can, in turn, result in catheter complications including both catheter related blood stream infection and thrombosis. Thrombus formation on catheter surfaces has been the subject of much research and product development efforts. For example, attempts to minimize thrombus formation on catheter surfaces have the incorporation of heparin, albumin and endothelial cells on the catheter surfaces. The permanent binding of biologically active moieties to catheter polymer chains or polymer surfaces has also been studied.
In U.S. Pat. No. 6,127,507, which is incorporated herein by reference for all purposes, it is proposed to use certain fluoroalkyl surface-modifying macromolecules in admixture with elastomers for the manufacture of blood-contacting medical devices. It is believed that the use of such macromolecules can result in a reduction in thrombosis formation on the medical device surfaces.
While additives such as fluoropolymers and other materials may impart beneficial properties to implantable medical devices, their addition to polymeric materials used to manufacture the medical devices may also adversely impact mechanical properties. The purity of such additives may also adversely impact these properties. As such, there is a need for additive compositional and/or purity requirements that yield advantageous anti-thrombogenic properties without compromising desired mechanical properties of medical devices made from materials that incorporate such additives.