Spring reinforced extensible catheter

Claim 1

An extensible catheter for use in a physiological fluid shunt system, said catheter comprising: a flexible tubular housing; an interior wall bounding a passage through the housing, the passage having a central axis; a flexible metallic helical spring having a plurality of identical turns and a constant inner and outer diameter, the said spring extending axially in the passage in abutment with said wall, the innermost boundary of said turns forming a guideway; a pair of conduit sections slidably mounted in apposition with one another within said passage, a head on each conduit section laterally projecting beyond the sections and making a sliding engagement with the said guideway, there being a flow passage through each sections and its head; and a pair of retainer members each making a fluid-sealing structural joinder with the housing adjacent to a respective end thereof, and projecting away from said housing, and having an inner peripheral surface which surrounds its respective conduit section so as to make a sliding, fluid-sealing fit with the outer wall of the respective conduit section and to retain the head in the passage, the relative axial lengths of the passage and of the heads being such as to permit the axial spacing apart of the heads to be varied, the heads sliding in the guideway and making sliding contact only with the said spring.