Guidewire having a controlled radiopacity tip

Claim 1

A controlled radiopaque guidewire comprising: an elongate central core wire having a reduced in diameter distal end portion, a rounded tip member having a back side to which is connected a distal end of said core wire; a first coiled spring wire having a proximal end fixed to said core wire in a proximal area thereof and a distal end fixed to said back side of said tip member; the coils of said first coiled spring wire being stretched or spaced in a distal end portion thereof; a second coiled spring wire having a proximal end fixed to said core wire and coiling outward therefrom to and between the spaced apart coils in said first coiled spring wire in said distal end portion of said first coiled spring wire and interleaved therebetween; a distal end of said second coiled spring wire being fixed to said back side of said tip member; said proximal end of said second coiled spring wire being spaced inwardly of and not in connection with coils of said first coiled spring wire such that said coils in said proximal end portion of said second coiled spring wire have a smaller diameter than said coils of said first coiled spring wire; said second coiled spring wire being more radiopaque than said first coiled spring wire; the spacing between the interleaved coils of said first and second coiled spring wires increasing gradually from the beginning of the interleaving to said tip member; and, at least one coil of said second coiled spring wire at said proximal end of said second coiled spring wire being wound tightly around a reduced in diameter portion of said central core wire and fixed to said core wire and not being welded or otherwise fixed to coils of said first coiled spring wire.