Vascular prosthesis and method of making the same

A vascular prosthesis comprising a flexible support tube having an inside diameter within the range of 1 to 30 millimeters and having a wall of open mesh construction with openings extending therethrough, a porous homogenous hydrogel layer secured to and extending along the inside of said tube and a porous heterogenous hydrogel layer secured to and extending along the outside of said tube, said homogeneous layer having pores extending therethrough of a maximum size less than 20 microns Feret diameter, and said heterogenous layer having pores of the same size as said homogenous layer and in addition having larger pores of a Feret diameter within the range of 20 to 200 microns, said inner and outer hydrogel layers extending into the openings of said wall of said tube.

A method for making a vascular prosthesis, comprising the steps of impregnating a porous flexible support tube with a polymerizable mixture of a monolefinic monomer and a minor proportion of a cross-linking agent dissolved in a first cosolvent medium comprising a first constituent in which both the monomer and polymer are readily soluble and a second constituent in which said monomer is soluble but said polymer is substantially insoluble, said second constituent exceeding 45% by weight of said polymerizable mixture, polymerizing said monomer in said first cosolvent medium to provide a cross-linked heterogenous hydrogel having a microstructure characterized by both microvoids and macrovoids, coating the interior of said tube with a second polymerizable mixture of the same monomer and cross-linking agent in a second cosolvent medium containing the same constituents as said first cosolvent medium but wherein said second constituent is less than 45% by weight of the polymerizable mixture, and polymerizing said monomer of said second mixture to produce a smooth hydrogel lining for said tube having a homogenous microstructure substantially free of macrovoids.

A method for making a vascular prosthesis, comprising the steps of impregnating a porous flexible support tube with a polymerizable mixture of a water-soluble monolefinic monomer and a minor proportion of a cross-linking agent dissolved in a first solvent consisting essentially of water and a water-miscible organic solvent, said water exceeding 45% by weight of said mixture, polymerizing said monomer in said first solvent to produce a cross-linked heterogenous hydrogel having a microstructure characterized by both microvoids and macrovoids, coating the interior of said tube with a second polymerizable mixture of the same monomer and cross-linking agent in a second solvent containing the same components as said first solvent but wherein the water content is less than 45% by weight of said second mixture, and polymerizing said monomer of said second mixture to produce a smooth hydrogel lining for said tube having a homogenous microstructure substantially free of macrovoids.