Catheter Stylets

Abstract

Catheter stylet having an elongated bodily flexible outer casing means comprising helically wound wire, and elongated reinforcing means extending generally axially therethrough comprising at least one strengthening portion.

Description

This invention relates generally to catheter stylets and, more particularly, to catheter stylets comprising portions of differing flexibility and to methods of manufacture thereof.

Catheter stylets of the class to which the present invention pertains may be utilized in a variety of surgical and medical operations and procedures. For example, and without limitation, such stylets may be inserted into or through bodily chambers and passages to function as mechanical probes, as supports for catheters, as guides for catheters, as electrodes, and the like.

It is of the utmost importance that a catheter stylet be so fabricated as to minimize breakage thereof while in a bodily cavity or passage and, preferably to substantially eliminate any such possibility. While such a possibility can be to a great extent minimized and, in fact, substantially eliminated, this may not, in all cases be sufficient. For example, presently catheter stylets are being utilized for percutaneous catheterizations into arterial and cardiac systems and, even, in direct cardiac catheterization. If a catheter stylet should break during such a procedure, the result could be fatal. In such situations, substantial elimination of the possibility of breakage may not be deemed sufficient but, rather, it is desirable that even in the unlikely event that a catheter stylet should break while in or extending through a bodily passage, chamber or organ that the entire catheter stylet be capable of removal without leaving any broken pieces disposed within the body.

Yet another criterion, however, of catheter stylets is that they be, in general, flexible. The degree of flexibility, however, manipulated many procedures should not be constant throughout the length of the stylet. For example, for percutaneous, arterial and direct cardiac catheterization, it is desirable that the distal end portion of the stylet be quite flexible to preclude any possibility of damage to cardiac and/or vascular tissue by contact therewith, and to follow easily around curves in the vascular system. However, it is preferable that the remainder of the stylet be somewhat stiffer or less flexible than the distal end portion to enable the catheter stylet to be readily and easily directed to the desired location and to be capable of sustaining the required flexural forces without buckling.

Still further, it is exceptionally desirable that catheter stylets be capable of being readily sterilized, and be smooth and easily manipulated. However, it must be borne in mind that catheter stylets may be of exceedingly small diameter, on the order of 1 to 2 millimeters in diameter and quite long, and may, for example, be approximately 150 centimeters long.

Having in mind the foregoing, it is a primary object of the present invention to provide novel catheter stylets and methods of manufacture thereof.

Another primary object of the present invention, in addition to the foregoing object, is the provision of catheter styles comprising portions of differing flexibility and methods of manufacture thereof.

Yet another primary object of the present invention, in addition to each of the foregoing objects, is the provision of such catheter stylets which are constructed and arranged to preclude the possibility of a tip portion breaking away therefrom and being left within bodily passages or cavities and methods of manufacture thereof.

Yet still another primary object of the present invention, in addition to each of the foregoing objects, is the provision of such catheter styles comprising a helical spring wire casing, a stiffening member extending partially therethrough and retaining means connected with the stiffening means and extending through the remaining portions of the casing to retain the entire stylet as a single unit even if the casing should break and methods of manufacture thereof.

Another and yet still further primary object of the present invention, in addition to each of the foregoing objects, is the provision of such catheter stylets which are electrically conductive enabling utilization thereof as an electrode for bioelectronics such as cardiac defibrillation, cardiac pacing, electrocardiography, the transmission or reception of electrical signals or impulses from substantially any bodily location, and the like and methods of manufacture thereof.

Yet still another primary object of the present invention in addition to each of the foregoing objects, is the provision of such cardiac stylets capable of utilization as a guide wire for the insertion of open-ended catheters into bodily passages such as, and by way of example only, in accordance with the Seldinger technique for inserting a catheter into a blood vessel, as for angiocardiography, or the like, and methods of manufacture thereof.

Yet still further, it is also a primary object of the present invention, in addition to each of the foregoing objects, to provide such catheter styles which are simple, easy, and inexpensive to manufacture and use which may be readily and easily sterilized.

IN THE DRAWING:

FIG. 1 is an enlarged partial cross-sectional illustration of the distal end portion of a catheter stylet constructed in accordance with the principles of the present invention and

FIG. 2 is a cross-sectional view taken along line 2--2 of FIG. 1.

With reference now to the drawing, there is shown and illustrated a catheter stylet or guide wire constructed in accordance with the principles of the present invention and designated generally by the reference character 10. The stylet or guide wire 10 may comprise an outer casing 12, a distal tip 14, stiffening means 16 and reinforcing means 18. The outer casing 12 is preferably of highly flexible material and may, for example, comprise a continuous helical coil of hardened and tempered stainless steel spring wire. For example, the casing 12 may be fabricated of a stainless steel wire of approximately five to seven-thousandths diameter so that the casing 12 would be approximately 0.024 inch inside diameter.

Such a casing would be quite flexible and capable of being literally bent during passage, for example, through blood vessels, or the like. Moreover, such a construction would not be easily broken but, upon continued flexing of the casing 12 minute fractures could occur. Furthermore, since metals are not generally homogeneous, tiny flaws, carbon spots, or the like could produce a location more susceptible to breakage. No matter what inspection procedures are utilized, such a fine wire, when would into helical coil spring configuration, could not be safely relied upon, without reinforcement, as a catheter stylet or guide wire such as that of the character described since some slight possibility would always exist of such a wire fracturing during use.

To provide a generally rounded nose or distal end to the casing 12, the tip 14 may be provided to aid in guiding the stylet 10 and to preclude the distal end portion thereof from tearing, piercing, or otherwise injuring bodily tissues. The tip 14 may, for example, be formed of metal, plastic, or the like. For example, the distal end or tip 14 may be fabricated of solder, silver solder, or other molten metal by dipping the distal end portion of the casing 12 into a molten bath or by heating the distal end portion and applying solder or silver solder thereto in the form of a wire, or the like. However, the distal end tip 14 may also be fabricated of a plastic material, such as an epoxy cement, or the like.

The medical utilizations of the catheter stylets or guide wires 10 constructed in accordance with the principles of the present invention generally require that only the distal end portion be exceptionally flexible, while the remainder of the stylet or guide wire be somewhat stiffer. For example, it is often desirable that approximately the distal 3 centimeters of the stylet be exceedingly flexible to aid in guiding or steering the stylet through the bodily passages and to preclude damage to bodily tissues due to contact, tremor or the like.

As an aid in inserting and steering the stylets, it may be preferable that the remainder of the casing proximal of the distal 3 centimeters referred to above be stiffened or reinforced and the reinforcing means 16 may be inserted within the casing 12 extending from the proximal end (not shown) to a location approximately 3 centimeters from the distal end. The reinforcing means 16 may, for example, comprise stainless steel hypodermic tubing having, for example, an outside diameter of approximately 0.020 inch and an inside diameter of approximately 0.010 inch. Since, as heretofore pointed out, the casing 12 may have an internal diameter of approximately 0.024 inch, it may be readily seen that there is a clearance of approximately 0.002 inch between the hypodermic tubing or reinforcing means 16 and the interior of the casing 12 enabling the reinforcing means or hypodermic tubing to be inserted therewithin.

The distal end portion of the reinforcing means or hypodermic tubing 16 may be secured with the casing 12, as b means of an epoxy cement, solder, or the like. Epoxy cement, however, is exceptionally suitable in that its high wetting ability enables the formation of a firm bond even at such generally inaccessible location as between the periphery of the hypodermic tubing 16 at the distal end portion thereof and the interior of the casing 12 adjacent thereto. If desired, the proximal end portion of the reinforcing or stiffening means 16 may be similarly secured with the casing 12.

As heretofore pointed out, it is a primary desideratum that any possibility of breakage of the casing 12 and subsequent separation thereof so as to leave a portion thereof disposed within the body of a patient be absolutely precluded. As heretofore pointed out, the likelihood of breakage may be substantially reduced by proper design, heat treatment ans inspection. However, as also heretofore pointed out, design to positively eliminate breakage is substantially impossible within the limits of size dictated by the use.

It is believed readily obvious, however, that the only danger of breakage such as would leave a portion of the stylet within a patient's body would be if the stylet fractured at the 3 -centimeter flexible distal end portion since the stiffening means 16 serves, additionally, to reinforce the remainder of the stylet. If, however, the casing should fracture within the distal 3 centimeters, then the hypodermic tubing 16 would not be effective to enable removal thereof and, accordingly, the tip 14 and distal end portion of the casing 12 could be released into the body.

To preclude such a possibility, the stylet 10 may further comprise the safety-reinforcing means 18 which, for example, may comprise a strand of stainless steel wire or cable extending between the tip 14 and the hypodermic tubing 16. While substantially any material may be utilized for the safety-reinforcing means 18, a strand of stainless steel wire or cable has been found preferable in that it is sufficiently flexible as to not adversely affect the flexibility of the distal end portion while being sufficiently strong as to substantially eliminate any danger of breakage. With the wire or cable 18 extending between the hypodermic tubing 16 and the tip 14, even if the casing 12 should fracture within the distal 3-centimeter portion, then upon withdrawal of the hypodermic tubing 16 and casing 12, the wire or cable 18 will pull the tip 14 at adjacent portion of the casing of outwardly if the body. The wire or cable 18 may, for example, comprise a 5- or 7-strand stainless steel cable having an effective outside diameter of approximately 0.007 inch. The proximal end portion of the safely restraining wire 18 may be secured within the distal end portion of the hypodermic tubing 16, as by means of an epoxy cement 20. The distal end portion of the safety wire 18 may be embedded within the tip 14 during formation thereof and, for additional safety, may be formed with a bight 22 to preclude any pulling out or separation therebetween.

Similarly, any desired portion or portions of the stylet 10 may be constructed and arranged to have maximum flexibility by omitting the reinforcing or stiffening tubing therefrom while precluding breakage and separation thereat by the incorporation of a reinforcing wire or cable therethrough. Likewise, any desired portion or portions of the stylet 10 may be made more or less stiff by the incorporation of reinforcing or hypodermic tubing therewithin, the particular outside diameter, inside diameter, composition, and temper of the hypodermic tubing at such portion or portions being effective to control the stiffness or flexibility thereat.

It is to be expressly understood, however, that for maximum safety each and every longitudinal portion of the stylet would comprise both an outer casing and an inner generally axially extending member, with that member being either a relatively stiff member such as hypodermic tubing or a bodily flexible member, such as twisted wire or cable. Furthermore, to preclude breakage or separation, the inner member is preferably continuous that is, comprises portions of tubing and wire or cable interconnected and in line. The distal and proximal end portions of the inner member may be secured with the outer casing as described above. Similarly, the distal and proximal end portions of each of the hypodermic tubing sections or portions may also be secured with the outer casing as by an adhesive bond.

The inner member may be secured with the outer casing in substantially any manner, but as hereinabove pointed out, na adhesive bonding therebetween is especially suitable. Substantially any adhesive-type material may be utilized, including metals such as solders, silver solders, or the like or more conventional adhesives, such as epoxy adhesives. Preferably, the adhesive, whether it be a metal or an organic material, maximum of tensile strength with a minimum bending momentor or maximum be one which in the liquid state thereof exhibits the property of highly wetting the outer sheathing, the wire or cable and the hypodermic tubing enabling such wetting action to cause the adhesive to flow into the narrow spaces between the outer sheathing, wire or cable and tubing to provide firm bond therebetween. As pointed out above, epoxy adhesives have been found to be especially suitable and capable of sustaining or undergoing sterilization processes.

While the reinforcing means may comprise substantially any elongated structure capable of being disposed within the casing means, it has been found preferable that the bodily flexible reinforcing means 18 comprise multiple-stranded twisted wire rope to provide a maximum of tensile strength with a minimum bending momentor or maximum resistance to bending with a minimum of material and enabling secure axial or concentric joining with bodily flexible reinforcing means 18.

Moreover, it is believed particularly pertinent to note that stylets constructed according to the present invention are constructed and arranged to preclude stretching, even of the distal end portion, under tension, such as might occur if, for example, the distal end may be caught upon withdrawal as the whole stylet moves rearwardly. This is a very dangerous procedure, and it is under such conditions that the greatest danger of breakage exists.

Since the distal end portion of the stylets constructed in accordance with the present invention are precluded from stretching, the safety thereof is immeasurably greater than stylets heretofore known.

Claims

What is claimed is:

1. A catheter stylet comprising, in combination, an elongated bodily flexible outer casing means a flexible tip portion and a main body portion, said means elongated bodily flexible outer casing means comprising helically wound wire, an elongated hollow tubular reinforcing and stiffening element entirely within said casing and extending axially throughout said main body portion, and a reinforcing bodily flexible strand portion disposed axially through both said tubular element and said flexible tip portion whereby the overall structural integrity if the stylet is increased, and separate bonding means securing both of the inner and outer walls of said tubular element to said strand and said outer casing respectively.

2. Catheter stylet as defined in claim 1 further including means securing said stiffening element against movement relative to said casing means.

3. Catheter stylet defined in claim 2, wherein said bodily flexible strand portion comprises multiple wire strands.

4. Catheter stylet defined in claim 3, wherein said multiple strands are twisted to define a wire rope.

5. Catheter stylet defined in claim 4, further comprising means securing said bodily flexible portion to said stiffening element.

6. Catheter stylet defined in claim 5, wherein said securing means securing said stiffening element against movement relative said casing means and said securing means securing said bodily flexible portion to said stiffening element comprising a material selected from the group consisting of epoxy, solder and silver solder.

7. Catheter stylet defined in claim 6, further comprising means securing the distal end portions of said casing means and said flexible portion to preclude breakage and separation of said stylet.

8. Catheter stylet defined in claim 6, wherein said tubular portion extends proximally of a location spaced apart from the distal end portion of said casing, wherein said bodily flexible strand portion extends to said distal end portion of said casing and wherein the style further comprises means securing the distal end portion of said bodily flexible portion and the distal end portion of said casing means.

9. Catheter stylet defined in claim 8 wherein said securing means comprises a bight formed in said bodily flexible portion.

10. Catheter stylet defined in claim 8 wherein said securing means comprises a material having the characteristics of epoxy.