Vascular prosthesis and method in producing it

Claim 1

A method of producing a vascular prosthesis comprising (1) mounting a tube of a biologically acceptable resinous material in relation to a laser means producing two focused beams directed to the outer surface of said tube from opposite sides thereof, whereby said tube and said laser means can move rotationally relative to each other around the longitudinal axis of said tube, and transversely relative to each other parallel to the longitudinal axis of said tube; (2) moving said tube rotationally relative to said laser means and simultaneously moving said tube axially relative to said laser means whereby the focus of light from said laser means traces a helical pattern on the surface of said tube; (3) focusing pulsed beams of light from said laser on the surface of said tube during said rotation; and (4) controlling the energy of each pulse and directing the beams to form microdepressions in the surface of said tube, the depth of which are not more than about 75% of the thickness of the wall of the tube, and wherein the microdepressions formed by the two laser beams intersect within the wall of the vascular prosthesis, thereby forming an interconnected hole which extends from one position on the external surface of the tube, and concurrently controlling the frequency of said pulses relative to the rotational and axial movement of the tube in relation to the laser beams such that the pulsed beams form a regularly spaced helical array of microdepressions in the surface of said tube.

Claim 2

A method of producing a vascular prosthesis comprising (1) mounting a tube of a biologically acceptable resinous material in relation to a laser means producing two focused beams directed to the outer surface of said tube from opposite sides thereof, whereby said tube and said laser means can move rotationally relative to each other around the longitudinal axis of said tube, and transversely relative to each other parallel to the longitudinal axis of said tube; (2) moving said tube rotationally relative to said laser means and simultaneously moving said tube axially relative to said laser means whereby the focus of light from said laser means traces a helical pattern on the surface of said tube; (3) focusing pulsed beams of light from said laser on the surface of said tube during said rotation; and (4) controlling the energy of each pulse and directing the beams to form microdepressions in the surface of said tube, the depth of which are not more than about 75% of the thickness of the wall of the tube, and wherein the microdepressions formed by the two laser beams intersect within the wall of the vascular prosthesis, thereby forming an interconnected hole which extends from one position on the external surface of the tube, and concurrently controlling the frequency of said pulses relative to the rotational and axial movement of the tube in relation to the laser beams such that the pulsed beams form a regularly spaced helical array of microdepressions in the surface of said tube.