1. Field of the Invention
This invention is directed to coatings for implantable medical devices, such as pacing leads.
2. Description of the State of the Related Art
Pacing leads are widely used for treatment of a variety of heart ailments, for example, irregularity of the heart beat. It is desirable to be able to use the pacing lead not only for defibrillation, but also as a vehicle for providing biological therapy.
Biological therapy can be achieved by medicating pacing leads. One method for medicating pacing leads involves the use of a polymeric carrier coated onto the surface of a pacing lead. A solution which includes a solvent, a polymer dissolved in the solvent, and a therapeutic substance dispersed in the blend is applied to the pacing lead. The solvent is allowed to evaporate, leaving on the pacing lead surface a coating of the polymer and the therapeutic substance impregnated in the polymer.
For the purposes of pharmacological therapy, it is important to maintain the concentration of the drug at a therapeutically effective level for an acceptable period of time. Hence, controlling a rate of release of the drug from the pacing lead is important, especially in such a way so as to decrease the release rate of the drug from the underlying matrix. It is also desirable to be able to rapidly increase the rate of release of the drug during the process of defibrillation, and then to return quickly to slow delivery of the drug.
In view of the foregoing, coatings capable of pulsatile drug delivery from pacing leads, are desired. Embodiments of the present invention disclose such coatings and methods for fabricating thereof.