Catheter with irregular inner and/or outer surfaces to reduce tr

Details Catheter with irregular inner and/or outer surfaces to reduce tr Catheter with irregular inner and/or outer surfaces to reduce tr

1993-11-02

1996-03-05

Rimell, Sam

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

604280, 128657, A61M 2500

Patent

active

054962927

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention relates to a method of making tubular products, especially catheters. More particularly, this invention relates to a method for making a reinforced catheter having an irregular lumen surface to reduce friction when used as a guiding catheter for the passage of another catheter through the lumen or the rotation of another catheter within the lumen. Still more particularly, this invention relates to a method of making a catheter wherein either or both elongated axial surfaces of a catheter are modified to decrease mechanical friction due to fluid coupling by causing the surfaces to have a non-linear or non-smooth character, thus to limit contact area with any adjacent structure to relatively small areas or line or points rather than the entire geometric surface or relatively large surfaces.
As explained in U.S. Pat. No. 4,764,324, the art of manufacturing tubes, pipes or cannulae by extruding a plastic material to produce significant quantities of tubing is fairly well developed. In many instances, it is desirable to use reinforcement in the tubes or pipes to increase the pressure, tensioning, or torque-carrying capacities of those tubes or pipes. Ordinary plastic garden hose reinforced with filament is a common example of such a product made according to prior art techniques, as is a catheter for applications in the medical field.
Catheters of the type contemplated are relatively thin and flexible tubes which include inner and outer plastic layers with a wire sheathing embedded between the layers wherein the wire sheathing is either braided or cross-wound to obtain maximum torsional rigidity and a satisfactory longitudinal flexibility. A convention prior art process for making a reinforced extruded catheter is a three-step process. In the first step, a mandrel having an outside diameter about equal to the desired inside diameter of the finished catheter is passed through suitable extrusion tooling to cause a tubular jacket or sheath of the catheter material to form around the mandrel. In this step, the outside diameter of the first extrusion layer on the mandrel is smaller than the desired finished outside diameter of the finished catheter. Next, the inner core tube formed in the first step as described above is processed by suitable machinery to cause a pattern of reinforcing materials, such as wires, fibers, or monofilaments, for example, to be laid along and/or around or partially into and in contact with the surface of the core tube. Next, the composite intermediate structure of the inner core tube and the reinforcing layer thus applied is again passed through suitable extrusion tooling equipment to deposit a second layer of catheter material around and bonded to the composite thereby encapsulating the now reinforced inner core tube forming essentially a single structure. The outside diameter of the second layer of extrusion is approximately equal to the desired finished outside diameter of the catheter. Subsequently, finishing and polishing operations can be performed and a composite thus constructed cut to its desired length. The mandrel, if any, is then extracted by lengthwise pulling, leaving the hollow catheter tubing with reinforced walls. That process produces a catheter with smooth, uninterrupted inner and outer circumferential surfaces.
U.S. Pat. No. 4,764,324 to the applicant herein constitutes a significant improvement on that three-step process by recognizing that heating the polymer substrate, or the reinforcing material and a polymer substrate beneath it, during a process of manufacturing a catheter, while simultaneously applying axial tension to the reinforcement, will cause the reinforcement material to deform or penetrate the original surface of the catheter body polymer and thus penetrate into such a surface. The distance to which the reinforcement material sinks into the underlying polymer is highly controllable and repeatable depending on the conditions of the relative temperatures of the catheter body and the reinforcement material, as wel

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