Reinforced catheter with thin monolithic walls

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REINFORCED CATHETER WITH THIN
MONOLITHIC WALLS

BACKGROUND OF THE INVENTION 5

I. Field of the Invention

The present invention relates generally to the field of catheters. More particularly it relates to guiding catheters having torque transmittal guidance walls that are flexible linearly but not circumferentially and that are neither collapsible nor kinkable. It is particularly suited as a vascular catheter.

II. Description of the Prior Art

Vascular catheters and some other types of catheters 15 requiring remote guidance of insertion from outside of a patient have fine spiralled or braided metallic or nonmetallic strands of reinforcement material in thin cylindrical walls of flexible catheter tubing. The catheter body must (a) contain fluid pressures up to 1,000 psi, (b) 2Q transmit rotational torque accurately from a proximal end outside of a patient to a distal end inside of the patient, (c) prevent collapse, kinking or alteration of conveyance area of the catheter, (d) convey electrical current or sound wave energy from end-to-end of the 25 catheter and yet, (e) flex sufficiently not to injure bodily tissues. Diagnostic instrumentation, traceable fluids, medicine and body fluids must be conveyed through the catheter lumen effectively. Total diameter of the catheter tubing, however, is often less than one-tenth of an 30 inch.

Guidance of such catheters within vascular and other body channels is achieved usually by selectively slight rotation of the catheter with a small handle at the proximal end. At the distal end near a non-injurious tip of the 35 catheter inside of the patient, there is generally a curved directional bend. The slight rotation of the catheter points this directional bend precisely in a desired circumferential direction at a particular position of confluence or other physical condition of the body lumens or 40 channels. This directs or guides insertional advancement of the catheter into desired body channels or lumens. Other guidance means employ unbent catheters in combination with various steerable tips.

A variety of problems have occurred with these small 45 guiding catheters and related components previously. One problem has been a tendency of reinforcement strands to separate from polymer or various flexible materials from which the body of the catheter tubing is constructed. This destroys rotational torque transmittal 50 capacity and leaves the catheter subject to Tanking, collapse and general failure of its design requirements.

Another problem has been insufficient lubricity of inside catheter walls for conveyance of instrumentation, liquids and slurries of diagnostic and medicinal mated- 55 als with low viscosity. Outside walls of catheters also have had inadequate lubricity for passage in and out of relatively small body channels.

Another problem has been inadequately resilient directional bends at distal ends of catheters. Some have 60 been too rigid. Others have been the opposite without sufficient resilience memory to regain a directional curve after being straightened or bent differently in various portions of body channels.

A relatively common problem has been incapacity of 65 a catheter having sufficient linear flexibility to convey rotational torque between a reinforced catheter body and a desirably flexible or soft catheter tip.

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Still another problem has been incapacity of previous catheters to be drilled or welded to form side apertures referred to as perfusion ports. The walls of present catheters delaminate, separate and fail from heat of either drilling or welding.

Solving these and other problems has inspired this invention.

Different but pertinent catheter technology is described in the following patent documents.

The Frassica European Patent taught rolled layers of polymeric film interspersed with reinforcement materials and various instrumentation elements. High versatility of construction was a main feature of that patent. A wide variety of features could be provided at various portions of the catheter body. Problems, however, were tendency of the layers to separate, large diameter, ridges at linear and circumferential joints and high production cost to achieve variations. Also different from this invention, it could not be customized by mere programming of most of its features into a production process.

The Burnham Patent taught a single extrusion method based ■ on tensioning reinforcement strands being wound around heat softened thermoplastic catheter walls to draw the strands radially into the walls after they were formed. Different from this invention, however, it was not a process that applied catheter wall material inside and outside of the reinforcement strands during a simultaneous co-extrusion and strand winding process to form monolithic walls with tightly woven reinforcement strands. It had no solid lubrication in its walls. There was no wall interruption or channelling for friction reduction. Its reinforcement was not sufficiently variable linearly. There was no means for welding tips in close proximity to torque transmittal reinforcement strands to transmit torque effectively or to prevent tips from coming off inside of patients. Nor was there means for providing profusion ports and other features without destroying structural integrity of the catheter.

The Krasnicki et al Patent described an endoscope biopsy channel with a lubricous inner layer bounded by high strength wire helically wound around it. A soft outer layer provided protection against injury of tissue. Flexible material filled space between wire strands and between the lubricous inner wall and the soft outer wall. That catheter was not producible with sufficiently small diameters and thin walls. Separate walls inside and outside of helical windings consume too much space for small diameter production or for space efficient large diameter catheters.

The Wilson Patent taught a method to form what it referred to as a monolithic construction of cannulae that could be used for a catheter. Reinforcement strands were wound around the outside of a catheter tube that was then heated to cause the strands to adhere to the outside of the tube. In an optional subsequent step of the method, an additional layer of material was extruded onto the outside of the reinforcement strands. Unlike this invention, however, that method was not a simultaneous co-extrusion and wrapping process that formed a more integrated monolithic wall with less likelihood of 5 separation. There was no solid lubricant at surfaces nor friction reduction channels between solid lubricant surfaces. There was no method for attaching integral tips nor providing profusion ports without destroying structural integrity. 10

The Van Tassel et al Patent taught the attachment of a soft balloon like tip to ends of catheters. But it was not a method that could be used for attachment to reinforced walls because it required step cutting of the catheter wall. 15

The Alston, Jr. et al Patent positioned flat wire braiding between layers of material. This required thick walls in proportion to diameter of catheters. Separation of the layers was problematic for thin walls with that type of construction. It was not a monolithic type of wall 20 taught by this invention.

The Cook Patent employed conventional sandwiching of fiberglass woven roving between plastic layers of tubing. Walls were far too thick for the conveyance efficiency required for current medical practices. 25

The Polanyi et al Patent combined a wide variety of catheter features in a catheter wall. But the constructional form was far too thick and the cost of construction too high in comparison to present catheters. It was one of the first catheters to utilize fiber optics, but in 30 forms that have been superseded with smaller and more efficient fiber optics and diagnostic equipment made possible with this invention. Its walls and linear components would separate if made sufficiently thin for current catheter applications. 35

SUMMARY OF THE INVENTION

In accordance with the present invention, it is contemplated that one objective of this invention is to provide a catheter with a high ratio of torque transmittal 40 capacity from end-to-end for accurate and reliable rotational positioning of a guiding tip at a distal end of the catheter.

Another objective is to provide selective resilience and circumferential torque transmission at different 45 linear portions of a catheter.

Another objective is to provide high lubricity of both inside and outside peripheral surfaces of a catheter.

Another objective is to provide perfusion ports at select portions of a catheter without weakening torque 50 transmission, cylindrical integrity, structural integrity, flexibility or resilience of a catheter.

Another objective is to provide a catheter having thinner walls and a smaller outside diameter in proportion to inside diameter than present catheters. 55

Another objective is to provide a soft and smooth catheter tip immediately at the distal end of either progressively decreased or continued reinforcement density of a catheter.

Yet another objective of this invention is to provide 60 methods for constructing catheters having characteristics provided by this invention.

This .invention accomplishes the above and other objectives with a catheter having strands of resilient reinforcement material integrally spiraled or braided 65 into monolithic walls of flexible material. A solid lubricant, also referred to as dry lubricant, comprised of either special fluorine containing materials or polymeric

organic silicon compounds is embedded into interior and exterior wall surfaces of the catheters. Smooth interior walls are channeled to decrease friction resistance, to trap resistance particles and to dissipate friction heat in the high ratio of surface area to cross-sectional area of small catheters. Number of spirals or braids of reinforcement strands per unit of length, number of layers of strands of the catheters, catheter diameter and progressiveness thereof are designedly different for separate portions of particular catheters. Catheter tips are weldable immediately adjacent to select density of strands of reinforcement material. Perfusion ports are weldable where desired. Directional bends are positional selectively at distal ends of the catheters. Methods for manufacture and modification with co-extrusion, miniature milling and welding while maintaining structural integrity with monolithic wall structure are described.

Other objects, advantages and capabilities of the invention will become apparent from the following description taken in conjunction with the accompanying drawings showing preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cutaway side view of a luer and proximal end section of a catheter using this invention;

FIG. 2 is a distal end and tip of a catheter using this invention;

FIG. 3 is a cutaway sectional view of a catheter with reinforced monolithic walls in an embodiment of this invention;

FIG. 4 is a cutaway side view of prior art using layered rather than monolithic walls;

FIG. 5 is a cutaway side view of a monolithic wall with a ridged inside wall in an embodiment of this invention. It is positioned immediately beside the prior art which is so labeled for ease of comparison;

FIG. 6 is a layout of co-extrusion construction of this invention. Stages of construction of the catheter in select embodiments are related to co-extrusion steps shown in FIGS. 6a through 6h.

FIG. 6a is the first stage of production of the catheter showing a cross-section of the mandrel;

FIG. 6b is a stage of production at the first extrusion die which extrudes a first portion of the catheter wall;

FIG. 6c is the stage of production where one or more strands of inside reinforcement are wrapped onto the outside diameter of the first portion of the catheter wall;

FIG. 6d shows a stage of production of the second extrusion die which is employed to extrude a second portion of the catheter wall;

FIG. 6c shows the production stage of the catheter tube being provided with friction reduction channels in accordance with the invention;

FIG. 6/is the production stage showing a third extrusion die employed to extrude additional molten catheter material infused relationship to the existing catheter wall;

FIG. 6g shows a production step employing a linear positioner to position linear diagnostic components;

FIG. 6h is a production step showing the covering of the diagnostic components of the stage of FIG. 6g with additional material extruded from a fourth extrusion die;

FIG. 7 is a section of etched mandrel of an in place type employed for particular spiral or opposite direction spiral embodiments of this invention;