Vascular grafts with multiple channels and methods for making
A wall, for example the wall of a vascular graft, has multiple channels within it. The channels may be used to hold drugs or reinforcing fibers. The channels may have a predetermined roughness. The channels may be formed by coextrusion using a soluble material, for example, to define the channels and then dissolving them to open the channels in the extrudate.
1. A method of forming a medical device, comprising:
co-extruding a first material and a second material into a cylinder of the first and second materials, such that, after extrusion, the second material defines at least one elongate structure extending generally along a length of the medical device surrounded by the matrix of the first material; and
prior to implantation of the medical device within a patient
removing the second material from the first material to leave a void in the first material;
twisting the cylinder such that the voids left in the first material, after removal of the second material, are formed into helices;
inserting a reinforcement filament into the voids left in the first material; and
forming the medical device into a vascular graft.
2. The method of claim 1 wherein the second material is granular with a particle size of not more than 100 μm.
3. The method of claim 1 wherein the second material is a soluble material and the removing includes dissolving the soluble material.
4. The method of claim 1 further comprising expanding the first material after removing the second material.
5. The method of claim 1 wherein the first material includes polytetrafluoroethylene.
6. The method of claim 1 further comprising filling the voids left in the first material, after removal of the second material, with a drug.
7. The method of claim 1 further comprising filling the voids left in the first material, after removal of the second material, with an antithrombogenic drug.
8. The method of claim 1 further comprising filling the voids left in the first material, after removal of the second material, with a drug/polymer mixture.