Extensible Catheter

Abstract

A flexible cardiac or vascular catheter provided at its distal end with a smaller extensible and retractable flexible tubular extension particularly adapted to reach normally inaccessible treatment locations in vessels or branches thereof, the extension being movable axially of the catheter by means of a control wire the proximal end of which projects from the proximal end of the catheter.

Description

This invention generally relates to new and useful improvements in catheters and particularly seeks to provide a novel cardiac or vascular catheter having an axially adjustable flexible tubular tip extension.

The marked advances in cardiac and vascular surgery in the past few years and other medical problems that require diagnostic study of the vascular beds and systems has led to the extensive use of cardiac or vascular catheters, particularly for retrograde aortography and anginocardiography, and to take blood samples, determine oxygen content, infuse or inject medicaments at internal sites and various other uses that require the insertion of a relatively long catheter to an internal site that requires movement of the catheter into branch vessels at sharp angles relative to the feeding direction of the catheter or requires the distal end of the catheter to follow a sinuous path as it approaches the internal site.

The most common method for insertion of such catheters is the percutaneous technique described in 1953 by Sven Ivar Seldinger. In this procedure a local anesthetic is administered and a skin puncture made at a small angle to the vessel (e.g. femoral in the leg or brachial in the arm) with an obturator positioned within a cannula. Once the unit has been properly located in the vessel, the obturator is removed and a flexible spring guide is then inserted through the cannula into the vessel for a short distance. Pressure is then applied to hold the spring guide in place while the cannula is withdrawn. The spring guide is then fed into the vessel, generally under a fluoroscope, to the desired point which may or may not require considerable manipulation if there are branched vessels or curves concerned. Thereafter a catheter is passed over the flexible spring guide and fed into the desired position and the spring guide is then withdrawn from the catheter.

A particularly useful spring guide for these purposes is disclosed and claimed in my copending application for patent Ser. No. 563,927, filed June 29, 1966, now Pat No. 3,452,742. In that form of spring guide predetermined portions of its length may be controllably curved by manipulation of an inner tension wire from its proximal end outside the patient and it may also be curved after a catheter is placed thereover to cause the catheter to curve.

However, there are many conditions where even the great manipulative ability gained through the use of the above type of spring guide is not adequate to enable the distal tip of a catheter to be properly positioned, as where the desired treatment point is located a substantial distance along a small diameter branch vessel extending at a sharp angle from the vessel into which the catheter is inserted or where the desired point is located a substantial distance along a particularly sinuous portion of the vessel.

This problem is overcome through the use of a catheter constructed in accordance with this invention.

Therefore, an object of this invention is to provide a flexible catheter having an extensible distal end.

Another object of this invention is to provide a catheter of the character stated in which the distal end extension comprises a small diameter flexible tube normally housed completely within the distal end portion of the catheter lumen and is axially or angularly projectable therefrom through a suitably configured catheter tip.

Another object of this invention is to provide a catheter of the character stated in which the distal end extension is projected or retracted from the tip of the catheter by a manipulating wire extending through the full length of the catheter lumen with its proximal end projecting substantially beyond the proximal end of the catheter.

Another object of this invention is to provide a catheter of the character stated in which the manipulating wire is connected to the extensible tube by a swivel coupling so designed that injection or infusion liquids can pass from the lumen of the catheter into and through the lumen of the tubular extension.

With these and other objects, the nature of which will be apparent, the invention will be more fully understood by reference to the drawings, the accompanying detailed description and the appended claims.

In the drawings:

FIG. 1 is a side elevation, partly broken, of a catheter constructed in accordance with this invention and shows the extensible tube in its retracted position;

FIG. 2 is a view similar to FIG. 1, but showing the extensible tube in its fully projected position;

FIG. 3 is an enlarged fragmentary longitudinal section of the distal end of the catheter and shows the manipulating wire connector and one form of tip that may be used when the extension tube is to be projected axially;

FIG. 4 is a view similar to FIG. 3 but showing a form of tip that may be used when the extension tube is to be projected at an angle to the axis of the catheter.

FIG. 5 is an enlarged fragmentary longitudinal section of the distal end of a catheter modified to provide an integral tip used for the axial projection of the extension tube; and

FIG. 6 is a view similar to FIG. 5 but showing an integral tip used for the angular projection of the extension tube.

Referring to the drawings in detail, the invention as illustrated is embodied in a flexible catheter generally designated 5 having a proximal end 6 and a distal end 7, which may be formed from any suitable material such as (irradiated) polyethylene, nylon or a tetrafluoroethylene resin and which may be of uniform diameter or tapered as indicated in FIGS. 1 and 2 of the drawings. Whatever the material, it should be radiopaque in order that its progress of advance within a vessel and the positioning of its distal end may be observed through the use of a fluoroscope.

In one form of the invention (see FIG. 3) where the catheter is to be provided with an axially projectable tubular extension, the distal end 7 of the catheter is provided with a generally cylindrical rigid tip 8 tightly secured therewithin and having a full length longitudinal duct or lumen 9 of a diameter sufficient to permit the catheter to be applied over a spring guide and to permit a catheter extension tube to be passed therethrough following removal of the spring guide. A flexible catheter extension tube 10, preferably formed from a radiopaque silicone rubber or similar material and having an outside diameter such that is will freely slide within the catheter tip 9, is normally positioned within the distal end portion of the catheter with the distal end of the extension tube in registry with the distal end of the catheter. The extension tube may be of any desired length, but will generally be from 2 to 6 inches long.

The inner or proximal end of the extension tube 10 carries an internal metal or rigid plastic dilating ring or annulus 11, having an outside diameter substantially equal to or slightly greater than the diameter of the tip lumen 9, which forces the formation of a rounded shoulder 12 on the extension tube which becomes seated against the proximal end of the tip 8 when the tube is fully projected beyond the tip. The shoulder 12 also prevents the tube 10 from becoming expelled from the distal end of the catheter.

A cylindrical connector generally designated 13 has its distal end turned down to define an externally corrugated stud 14 that is inserted and retained within the proximal end of the extension tube 10 in abutting relation to the annulus 11. A heat-shrunk band or sleeve 14a may be used to secure the extension tube 10 on the stud 14. The stud 14 is provided with an axial recess 15 extending into communication with a radial aperture 16 to permit passage of liquid from the lumen of the catheter into and through the lumen of the extension tube 10.

An extension tube manipulating wire 17 is provided at its distal end with a bead or pellet 18 securely fastened thereto and freely fitted with a cylindrical recess 19 formed in the proximal end of the connector 13. That end of the connector is rolled over as at 20 to retain the pellet within the recess 19 while permitting it and the attached wire 17 to freely swivel or rotate in either direction with respect to the connector.

The proximal end of the wire 17, which extends a substantial distance beyond the proximal end of the catheter, carries a manipulating knob 21 which conveniently may be in the form of a small pin vise for ready attachment to and removal from the wire. Thus the wire may be moved in either direction to effect a corresponding movement of the extension tube 10.

In FIG. 4 of the drawings the distal end 7 of the catheter is fitted with an internal tip 22 in which one side of the central portion thereof is machined to define a curvilinear passageway 23 for forcing the distal end of the extension tube 10 to project outwardly at an angle with respect to the axis of the tip when the tube is advanced. The extreme distal end portion of the tip 22 is provided with an axial bore 24 of sufficient diameter to permit the catheter to be passed over a spring guide and to permit the spring guide to be withdrawn. The passageway 23 is so contoured and proportioned that the extension tube 10 will always follow the passageway rather than the bore 24.

In FIG. 5 of the drawings there is illustrated a modification in which the distal end of a catheter 25 is provided with an integrally formed axially aligned tip 26 of reduced diameter to define a curved inner shoulder 27 against which the shoulder 12 of the extension tube 10 may be seated when the extension tube is fully projected.

This same principle of integral tip formation may be employed where the extension tube 10 is to be projected at an angle to the axis of the catheter and is illustrated in FIG. 6 of the drawings. In this instance the distal end of a catheter 28 is provided with an integrally formed axially aligned tip extension 29 of reduced diameter which defines at its proximal end a curved inner shoulder 30 and which terminates at its extreme distal end in a tip 31 curved to direct the extension tube 10 at the desired angle with respect to the axis of the catheter.

In use, the manipulating wire 17 and its attached extension tube 10 is completely withdrawn from the catheter 5 and the catheter is advanced over a previously inserted spring guide to a position such that the distal end of the catheter approaches, but does not reach, the desired treatment point. Then the spring guide is withdrawn and the tubular extension 10 is reinserted into the catheter and advanced by the wire 17 until its distal end is in registry with the distal end of the catheter, after which the catheter may be rotated or otherwise manipulated as the extension 10 is advanced beyond the distal end of the catheter until its distal end reaches the desired treatment point.

If the treatment is to be simply the rapid injection of a liquid, it makes little or no difference whether or not the tube 10 has been fully extended so that its shoulder 12 seats against the proximal end of the tip 8 to prevent leakage of the injection liquid from the distal end 7 of the catheter per se. However, if the treatment is to be the prolonged low-volume infusion of a liquid, it is important that the catheter 5 and its extension tube 10 be so adjusted that when the distal end of the extension tube is at the desired treatment point it has been fully extended beyond the distal end 7 of the catheter to firmly seat the shoulder 12 against the proximal end of the tip 8 and thus force all of the infusion liquid to flow through the tube 10 and to prevent any leakage of the infusion liquid from the distal end of the catheter per se.

It is, of course, to be understood that variations in arrangements and proportions of parts may be made within the scope of the appended claims.

Claims

I claim:

1. A flexible catheter having a lumen extending its full length, the diameter of the lumen being reduced adjacent its distal end to form a proximally facing annular shoulder, a flexible tubular extension having an outside diameter permitting free axial sliding movement through said reduced diameter lumen, said extension being enlarged adjacent its proximal end to form a distally facing shoulder engageable with the first named shoulder to limit movement of the extension distally with respect to said catheter, the length of said extension from its distal end to its enlarged shoulder being greater than the distance from the distal end of the catheter to the annular shoulder in said lumen filamentary means extending from said tubular extension to and beyond the proximal end of the catheter for effecting sliding movement of said tubular extension relative to said catheter, and a coupling connecting the proximal end of said extension to the distal end of said filamentary means, the lumen of the extension being in communication with the lumen of the catheter proximally of both said shoulders.

2. The catheter of claim 1 in which said filamentary means is a wire carried within said lumen and having its distal end connected to the proximal end of said tubular extension.

3. The catheter of claim 1 in which a rigid internal tip is positioned within the distal end of said lumen and provided with a tube-directing passageway, said coupling for said filamentary means having its distal end connected to the proximal end of said tubular extension and its proximal end Swivel- connected to said means, and in which said means is a wire carried within said lumen and having its distal end swivel-connected to said connector.

4. The catheter of claim 1 in which said tubular extension is radiopaque.

5. The catheter of claim 1 in which the first and second shoulders are shaped to form, when engaged, a fluidtight seal.

6. The catheter of claim 1 in which the catheter is provided, adjacent its distal end with a laterally directed opening from its reduced diameter portion and with associated means for guiding the tubular extension into and through said opening when the extension is moved distally with respect to the catheter.