WO1993012713A1

WO1993012713A1 - Guidewire extension mechanism

Info

Publication number: WO1993012713A1
Application number: PCT/US1992/010937
Authority: WO
Inventors: Jeffrey L. Kraus
Original assignee: Danforth Biomedical Incorporated
Priority date: 1991-12-23
Filing date: 1992-12-15
Publication date: 1993-07-08

Abstract

A reversibly extendable guidewire system for use in medical procedures such as the insertion and exchange of catheter systems. The coupling mechanism employs a mating protrusion (152) and receptacle (156) connection with a protective sleeve (160), an elbowed extension segment (122) which couples with a mating tube having a side aperture (106) to connect the segments together, or a hook (146) and eyelet (132) configuration with a protective sleeve to couple the segments together.

Description

GUIDE I E EXTENSION MECHANISM

BACKGROUND OF THE INVENTION The invention generally relates to guidewires for use in medical procedures, more specifically to extendable guidewires for medical procedures including percutaneous transluminal angioplasty that enable the exchange of catheters, such as dilation balloon catheters, within a body vessel with preserved intra-luminal access.

A variety of over-the-wire catheters have been developed that permit the performance of a variety of therapeutic procedures within body vessels with less morbidity relative to the corresponding surgical alternatives. Typically, these catheters are advanced over guidewires to provide directional control.

Experience has shown that it is sometimes necessary to exchange catheters during the course of medical procedures. The need for an exchange procedure arises when a component originally placed inside a body vessel is discovered subsequent to its placement to be inadequate or inappropriate. In certain circumstances, it is desirable to perform the exchange procedure with preserved intraluminal access. This saves time and lowers the risk of patient injury in the event of inadvertent vessel closure. This approach to the performance of an exchange procedure is particularly desirable in the case of percutaneous transluminal coronary angioplasty. The performance of a catheter exchange procedure with preserved intraluminal access requires the use of a guidewire, the length of which exceeds the sum of (1) the distance from the body vessel requiring treatment to the surface of the skin and (2) the length of the segment of the catheter encompassing the guidewire. Originally, exchange wires were developed for this purpose. Exchange wires are particularly long wires which can be substituted for conventional guidewires in anticipation of the performance of a catheter exchange. Although effective in preserving intravascular access during the course of a catheter exchange, experience has found these wires to be cumbersome to use. More recently, extendable guidewires were developed which are substantially easier to use and equally effective in preserving intravascular access during the course of an exchange procedure. Extendable guidewires use attachable segments to incrementally increase the length of the guidewire and thereby function as both a standard guidewire and an exchange wire. The use of extendable guidewires eliminate the need to substitute guidewires having fixed lengths.

U.S. Patent No. 4,827,941 teaches an extendable guidewire for cardiovascular procedures which provides a connection between an extension section and a guidewire, the connection relying upon a friction fit. The coupling mechanism of this device has the disadvantage of requiring a degree of opposing longitudinal forces to join the two components together. Given the delicate nature of many narrow gauge guidewires, such an application of force frequently can result in kinks or bends which, if significant, can render the resulting extended guidewire useless.

U.S. Patent No. 4,966,163 also teaches an extendable guidewire for vascular procedures. This device uses male and female threaded sections to join an extension section onto a guidewire. Although a threaded engagement reduces the necessity of applying longitudinal force, such a male-female threaded configuration in a typical intravascular guidewire application requires threads to be fabricated in the range of 0.010 to 0.011 inches in diameter. Quality threads of this dimension are difficult or near impossible to fabricate using conventional technology. Sophisticated microfabrication technologies must be employed. As a result, these micro- threads are extremely costly to construct.

In brief, there exist disadvantages associated with the application of the coupling mechanisms used in the above- described devices when used to construct low profile and/or delicate guidewires. There exists a need for extendable guidewire systems which employ a coupling mechanisms between connectable segments that do not require the use of significant longitudinal force for engagement, thereby reducing potential for kinking, and incorporate a structure which is easy and inexpensive to fabricate using conventional technologies. Herein is described such a device.

SUMMARY OF THE INVENTION The invention provides a new and improved coupling mechanism for extendable guidewires which can be used in a variety of procedures, including coronary and peripheral vascular procedures.

In one embodiment of the invention, a first guidewire segment includes a hollow mating tube secured to the proximal end of the first guidewire segment. The mating tube includes an aperture tangential to the longitudinal axis of the tube and is open at the proximal end. A second guidewire segment has an elbow at its distal end. Coupling the second guidewire segment to the first guidewire segment is accomplished by first inserting the proximal end of the second guidewire segment into the aperture of the first guidewire segment until the proximal end of the second guidewire segment extends out beyond the proximal end of the first guidewire segment, and then pulling the second guidewire segment through the aperture from its proximal end until the elbow engages the aperture. Engagement of the elbow and aperture will secure the second guidewire segment longitudinally and axially in the mating tube and thereby couple the second guidewire segment with the first guidewire segment. Disengagement can be accomplished by pulling the second guidewire segment in the reverse direction completely out through the aperture. In another embodiment of the invention, a first guidewire segment and a second guidewire segment employ a coupling mechanism with a hook and eyelet configuration. In this embodiment, an eyelet is formed at the proximal end of the first guidewire segment. The second guidewire segment includes a hook located at its distal end. To couple the first guidewire segment and the second guidewire segment together, the hook of the second guidewire segment is engaged with the eyelet located on the first guidewire segment. A tubular sheath located on the first guidewire segment is then moved over the hook and eyelet connection junction to protect and secure the connection and provide a smooth outer surface for passing catheter systems over the junction. The aforementioned constructions of the coupling mechanism enable the extension of guidewires used in the performance of catheter-based medical procedures. The extension of such wires makes possible the use of previously installed conventional-length guidewires in the performance of catheter exchange procedures with preserved intraluminal access. Each of the coupling means permit reversible extension with less propensity to provoke kinks during this process relative to the prior art. In addition, all of the aforementioned constructions are easy to manufacture. These and other advantages will become apparent from the detailed description provided below.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. la is a perspective view of an alternative embodiment of the invention shown partially in section with a first guidewire segment and a second guidewire segment in the disengaged condition;

Fig. lb is a plan view of the alternative embodiment illustrated in Fig. la also shown partially in section with the second guidewire segment and the first guidewire segment in the fully engaged condition;

Fig. lc is a plan view of an alternative embodiment of the coupling means disclosed in Figs, la-lb shown partially in section with a first guidewire segment and a second guidewire segment in the disengaged condition;

Fig. Id is a plan view of the embodiment of the coupling means disclosed in Fig. lc shown partially in section with a first guidewire segment and a second guidewire segment in the fully engaged condition; Fig. 2 is a plan view of an outer sheath used in another alternative embodiment of the invention where a first guidewire segment and a second guidewire segment engage with a hook and catch coupling mechanism; Fig. 3 is a plan view of the proximal end of the first guidewire segment used in the alternative embodiment employing the outer sheath illustrated in Fig. 2, the first guidewire segment shown having an eyelet at the extreme proximal end;

Fig. 4 is a plan view of the embodiment employing the devices of Figs. 2 and 3, showing the second guidewire segment having a hook at the distal end which engages with the catch located at the proximal end of the first guidewire segment; Fig. 5 is a plan view partially in section of the alterative embodiment illustrated in Fig. 4, the outer sheath shown slidable over the hook and eyelet connection junction; and

Fig. 6 is a plan view partially in section of the alternative embodiment illustrated in Fig. 5 with the outer sheath positioned completely over the hook and eyelet junction coupling the first guidewire segment and a second guidewire segment together and providing a smooth outer surface to facilitate smooth passage of a catheter system over the device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to Figs, la and lb, another alternative embodiment of the guidewire extension mechanism is shown. In this embodiment, first guidewire segment 102 includes mating tube 104 disposed at its proximal end. Mating tube 104 includes aperture 106 formed near the proximal end 108 of mating tube 104. In this embodiment, the coupling mechanism embodies the engagement between the mating tube 104 and an extended end 112 of second guidewire segment 110. Second guidewire segment 110 is formed having an elbow 112 at its extreme distal end and providing a head 122 which extends slightly out radially from the longitudinal axis of second guidewire segment 110.

Mating tube 104 can be fabricated using materials similar to that of outer sheath 44 described in the previous embodiments, i.e., HYPOTUBE® or suitable alternatives, including slightly flexible materials. First guidewire segment 102 is formed having a tapered portion 114 which provides a

SUBSTITUTE SHEET smooth taper down to post 116. The outer diameter of post 116 is made substantially the same size as the inner diameter of mating tube 104. Mating tube 104 is secured to first guidewire segment 102 by bonding along taper portion 114 and/or post 116 using appropriate bonding material. When mating tube 104 is formed from HYPOTUBE® material, appropriate adhesive or soldering techniques can be employed.

Fig. lb shows first guidewire segment 102 and second guidewire segment 110 of this embodiment in the fully engaged condition. ₌To couple first guidewire segment 102 with second guidewire segment 110 in this embodiment, proximal end 118 of second guidewire segment 110 is inserted through aperture 106 into mating tube 104 and out open end 120. The entire length of second guidewire segment 110 is pulled through aperture 106 until head 112 engages the rim of aperture 106. Second guidewire segment 110 is constructed having an outer diameter slightly less than the inner diameter of mating tube 104. As such, head 122 extending outwardly from elbow 112 is secured within aperture 106. The dimensional outward extension of head 122 is limited, however, to prevent the formation of a potential snag when running a catheter system over the extension mechanism 100. Preferably, the outward extension of head 122 is flush with the outer diameter of mating tube 104 as shown in Fig. la. Disengagement of second guidewire segment 110 from first guidewire segment 102 is accomplished by pushing elbow 112 back out through aperture 106 in a reverse direction until second guidewire segment 110 is fully withdrawn from mating tube 104. Aperture 106 is located close enough to open end 120 to allow second guidewire segment 110 to be disengaged without bending mating tube 104. The relative location of the components in coupling mechanism 100 of this embodiment can be reversed if desired by constructing a second guidewire segment 100 having mating tube 104 and first guidewire segment having elbow 112 and head 122. Again, this embodiment is easy to construct, easy to engage and/or disengage and does not predispose to kinks in the respective guidewire segments. Figs, lc-ld illustrate an alternative embodiment to the coupling means disclosed in Figs, la-lb. This embodiment is similar to the previous in that it relies upon the engagement of elbow 112 and aperture 106 to couple the first and second guidewire segments together. This embodiment differs from the previous in that the distal end of second guidewire segment 110 can be installed directly into the proximal end of the first guidewire segment 102 as a result of slot 119 provided in the mating tube. Second guidewire segment 110 is secured in place by sliding cover tube 121 over slot 119. This coupling mechanism circumvents the need to run the entire length of second guidewire segment 110 through aperture 106 of the first guidewire segment 102 to accomplish engagement and disengagement. An additional alternative embodiment of the invention is shown in Figs. 2-6. This embodiment uses a hook and eyelet coupling mechanism. First guidewire segment 130 is shown in Fig. 8 having an eyelet 132 disposed at its proximal end 134. Eyelet 132 can be formed by tapering the outer diameter of first guidewire segment 130 down to a lesser diameter and bending it back upon itself to form an eye as indicated in Fig. 8. The eyelet is then secured by suitable soldering 136. First guidewire segment 130 also includes an outer sleeve 138 as illustrated in Fig. 4. Outer sleeve 138 can be formed of HYPOTUBE® consistent with the embodiments previously described. Second guidewire segment 140 of this embodiment is formed having distal end 142 with a tapered portion 144 configured to form a hook 146. Hook 146 includes open slot 148 which allows hook 146 to receive eyelet 132 as shown in Fig. 4. When hook 146 receives eyelet 132, first guidewire segment 130 is coupled with second guidewire segment 140 to thereby increase the effective length of the guidewire system just as in the previous embodiments. Following coupling, outer sleeve 138, which is disposed around first guidewire segment 130, is slid up and over the mating junction of eyelet 132 and hook 146 as indicated in Fig. 5. In the fully engaged condition as shown in Fig. 6, outer sleeve 138 completely covers the mating junction between first guidewire segment 130 and second guidewire segment 140 to provide a smooth outer surface for passing a catheter system over the length of the mating junction. Outer sleeve 138 is sized so that it snugly fits about second guidewire segment 140 to secure it into this position. The two guidewire segments can be disengaged by withdrawing the outer sleeve 138 and uncoupling hook 146 and eyelet 132. The respective coupling components on each guidewire segment can be reversed, if desired. This embodiment, like all embodiments previously described, provides a simple and efficient coupling mechanism for extending the length of the guidewire system.

The foregoing description of the preferred and alternative embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. For example, guidewire extension mechanism can be fabricated in alternative dimensions and from a wide range of materials including, but not limited to titanium, platinum, palladium, plastics, as well as suitable alloys, ceramics, relatively flexible materials or any combination thereof. Also, modification to the constructions discussed can be employed.

In addition, more than two segments could be made to couple together in any of the embodiments described using any combination of the applicable coupling mechanism(s) to form a multipart guidewire system with many possible lengths using three or more segments. The embodiments chosen and described in this description are, however, selected to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments or dimensions and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.

Claims

WHAT IS CLAIMED IS;

1. An extendable intravascular guidewire system, comprising: a first guidewire segment having a distal end and a proximal end and including a mating tube disposed on said proximal end, said mating tube having an open end and a side aperture; and a second guidewire segment having a distal end and a proximal end, said distal end including an elbow segment and a head, wherein said proximal end of said second guidewire segment can be inserted into the aperture and drawn through the open end until the elbow is contained in the mating tube with the head extending out through the aperture thereby coupling the distal end of the second guidewire segment with the proximal end the first guidewire segment.

2. The extendable intravascular guidewire system of claim 1, wherein the coupling of the distal end of the second guidewire segment with the proximal end of the first guidewire segment can be disengaged nondestructively.

3. A coupling mechanism in an extendable intravascular guidewire system for axially connecting a first guidewire segment with a second guidewire segment, comprising: a flexible first guidewire segment having a distal end and a proximal end, said proximal end including an eyelet; and a second guidewire segment having a distal end and a proximal end, said distal end including a hook portion, wherein said hook portion and said eyelet engage axially to couple the first guidewire segment to the second guidewire segment.

4. The coupling mechanism of claim 3 further comprising an outer sleeve slidably positionable over said hook portion and the eyelet when the first guidewire segment and the second guidewire segment are in an engaged condition.

5. The coupling mechanism of claim 4 configured to permit disengagement of the first guidewire segment from the second guidewire segment nondestructively.

6. An extendable intravascular guidewire system, comprising: a first guidewire segment having a distal end and a proximal end, the proximal end including a protrusion extending generally in the distal-to-proximal direction; a second guidewire segment having a distal end and a proximal end, the distal end including a receptacle, the receptacle configured to receive the protrusion to thereby couple the first guidewire segment and the second guidewire segment together axially; and a slidable collar disposed about the outer surface of the receptacle, the collar being positionable between a first position and a second position wherein said first position the collar does not inhibit movement between the protrusion and the receptacle and in the second position the collar is disposed about the receptacle to constrict the receptacle and thereby increase frictional engagement between the receptacle and the protrusion to substantially restrict axial movement of the protrusion within the receptacle and thereby secure the first guidewire segment to the second guidewire segment.

7. The guidewire system of claim 6 wherein the distal end of the second guidewire segment has a substantially constant outer diameter and the collar has an outer diameter substantially equal to the outer diameter of the distal end of the second guidewire segment.

8. The guidewire system of claim 6 wherein the collar has an outer diameter substantially equal to an outer diameter of the proximal end of the first guidewire segment.

9. The guidewire system of claim 6 wherein the collar is fabricated from materials including stainless steel.

10. The guidewire system of claim 6 configured to permit disengagement of the first guidewire segment from the second guidewire segment nondestructively.