CA2098737C

CA2098737C - Fluoroscopically viewable guidewire for catheters

Info

Publication number: CA2098737C
Application number: CA002098737A
Authority: CA
Inventors: James B. Daigle; Richard M. Demello; Bruce W. Flight
Original assignee: Boston Scientific Ltd Barbados
Current assignee: Boston Scientific Ltd Barbados
Priority date: 1991-10-31
Filing date: 1992-10-23
Publication date: 2005-07-12
Anticipated expiration: 2012-10-23
Also published as: JP3517786B2; US5253653A; WO1993008862A1; EP0610347A4; DE69221497D1; JPH07500749A; EP0610347A1; DE69221497T2; CA2098737A1; EP0610347B1

Abstract

A guidewire assembly (21) for measuring the size of occlusions in blood vessels which includes a guidewire having a flexible, distal end disposable in a blood vessel. The guidewire has a core wire (5) disposed within it which extends to the distal tip (31). A linear array of radiopaque markers (11) is disposed adjacent the distal tip of the core wire (5), The markers (11) are spaced from each other at predetermined distances, whereby to enable the user to accurately measure the size and diameter of occlusions in blood vessels using radiological techniques,

Description

dvo 93/08862 Pcriu~9zio9o73 _1_ FLUOROSCOF'TCALLY VIEWABLE GUIDEWIRE FOR CATHETERS
Field of the Tnvention The present invention relates to an improved catheter for treating a tissue target site which is accessible by a tortuous path through small vessels. More.specif:ically, the present invention relates to a guidewire for a catheter, the guidewire having a core wire disposed therein. The catheter of the present invention can be inserted into the small vessels and can enable a physician to identify the magnitude of the target site through radiography.
Description of the Prior Art Blood vessels and other tubular structures in the body often undergo narrowing and the formation of obstructions.
These vessels can be restored to their original diameters by variaus medical means, especially through the us.e of balloon catheters. A balloon catheter 20 dilates the ves-sels by expanding a balloon on the distal end portion of a catheter tube. Tl~e balloon tip is inflated by the physi-cian when it is placed within an occlusion of a blood ves-set and dilates the vessel to form a clear path there--thraugh. The catheter and the balloon are single piece units with the balloon being a thin catheter wall portion of predetermined 'shape and size. A guidewire is disposed within the catheter to stiffen it and to provide guidance to the site of the occlusion. The guidewire can also be used to stretch the balloon lengthwise in order to reduce the diameter so that it can be iwtroduced through the obstructed area. Guidewires usually axe made of radiopa- .
que material so that their precise location can be identi-fied during a surgical pracedure through fluoroscopic viewing.
Use of x-ray imaging to view the guidewire, however, does not always identify the extent of the occlusion.
Frequently there is a need to identify the length and PC'f/U592/09073 -.
thickness of 'the occlusion so 'that the physician can uti-lize the correct balloon size during the surgery.
In the prior art, the length a:rad thickness of the occlusion is frequently measured lby incrementally spaced marker bands on the outside of the catheter itself.
Catheters with marker bands frequently are limited in that they cannot alc~ays be positioned directly in the vessel or ' in a region of the vessel where the occlusion is located.
Special catheters for sizing occhasions in vessels have to been developed but they require multiple catheter use and exchanging one for another.
Exemplary of markers used on guidewires in the art is the balloon catheter disclosed by LeVeen, 4,448,195, in ' which a radiopaque wire is mitered by machining it at pre-determined locations. Miter cuts are used to measure dis-tances an fluoroscopic images since they can be identified on a screen or film. Additionally, the reference teaches banding the outer sleeve of the catheter at both ends of the balloon to indicate the balloon s position t~ the phy-sa.cian performing the surgery. We have found that miter-ing of the guidewire and banding of the sleeve is not the best solution to obtaining views of the size and shape of arterial occlusions. The miter cuts cannot be seen easily on x-ray images, however, and they intraduce weak points in the guidewire which makes it more breakable. Banding is less than desirable because the bands increase the dia-meter of the catraeter and make insertion and use more dif-ficult. Also exemplary of indicia disposed on the guide-' wire is the patent to Gambale et al, 4,922,924. The pat-ent discloses a bifilar arrangement where radiopaque and radio~transparent filaments are wrapped on a mandril to form a bifilar coil which provides radiopaque and radio-transparent area: on the guide wire. , The United States patent to Fettel et al, 3,978,8F3 discloses the use. of beads made of radiopaque materials to indicate the location of the tip of the catheter and the expandable balloon at the tip. We have found that the beads add bulk to the catheter and can make the insertion process more difficult. ' ' ~V~ 93/08862 P~ C/US92/09073 _3_ Summary of the Invention According to the present invention, we have invented a novel, flexible and shapeable guidewire for a catheter.
The guidewire of our invention has a radiopaque tip dis-posed at its distal end and a care wire is disposed within ;
the guidewire. Radiopaque markera are disposed on the r core wire in a gauging section located at the distal end of the guidewire to provide easil!~ identifiable reference points for observation of the length and thickness of the occlusion under study. The distal end of vthe core wire is disposed in predetermined registration with an inner sur-face of the tip and a linearly arranged array of rad:iopa-que markers are disposed on the distal end of the core wire and are spaced from each other at predetermined dis-tances. Since an image of the tip of the guidewire can be seen on x-ray images,and since the location of each of the markers is known and can be seen relative to the tip, the size and shape of occlusions being studied can b~ mea-sured. When the markers are disposed on the core wire of the guidewire, we have found that the disposition of the markers does not add to the diameter of the catheter thereby enabling the physician to easily and safely insert the catheter into a blood vessel.
In the present invention, the guidewire has features which permit it to be used as a gauging tool having an internal core wire that is tapered and having a portion of reduced diameter at .its distal end to receive an array of f radiopaque markers. These markers may be radiopaque mat-erials such as gold, silver, platinum, tantalum ar other radiopaque, biocompatible materials.
The markers preferably are in the form of rings. The outer diameter of each ring is equal to or less than the ' diameter of the main body of the core wire at its gauging section but greater than the diameter of the core wire at ;
its distal end. The inner diameter of each ring, 'that is the hole, may be substantially the same as the distal or gauging end of the core wire so that it can be fitted on to the gauging end. In the preferred embodiment the hale is larger than the core wire to provide a slip fit thereon.
Many ways can be used to make the markers. For example, radiopaque wire can be wound on a mandril that has a diameter slightly less than the diameter of the wire at the gauging section. The coil is then sliced into units of predetermined lengths. Radiopaque plastic tubing can be cut into segments or the markers can be formed of brazed or soldered material on the core wire.
The size, shape and location of each of the markers is highly important. Such dimensions and relationships enable the user to accurately gauge the area being measured with the guidewire gauging tool in closer proximity to the occlusion being measured. Moreover, the guide wire can be used to advance other devices such as an angioplastic balloon catheter or stmt device, thereby minimizing the need to exchange catheters or guidewires.
Because no significant bumps are on the gauging section, the guidewire can be easily withdrawn from a catheter that may house it.
The invention may be summarized according to one aspect as a fluoroscopically viewable guidewire for a catheter to measure the size and shape of occlusions in a blood vessel, said guidewire comprising: a core wire having a flexible distal end formed of a body section which tapers into a gauging section; a proximal marker means, a distal marker means and at least one intermediate marker means, each of said marker means being radiopaque and linearly disposed on said gauging section, said marker means being 4a spaced from each other at a predetermined distance; and a helical coil of radiotransparent flexible wire surrounding at least the gauging section of said core wire.
The invention may be summarized according to another aspect as a fluoroscopically viewable guidewire for a catheter to measure the size and shape of occlusions in a blood vessel, said guidewire comprising: a core wire having a flexible distal end formed of a body section tapering into a gauging section; a proximal marker ring, a distal marker ring and at least one intermediate marker ring disposed between said proximal and distal marker rings, each of said marker rings being radiopaque and linearly disposed on said gauging section, the diameter of said marker rings being substantially the same as the diameter of said body section, Z5 said marker rings being spaced from each other at predetermined distances, and a helical coil of radiotransparent flexible wire surrounding at least the gauging section of said core wire.
The invention may be summarized according to another aspect as a fluoroscopically viewable guidewire for a catheter to measure the size and shape of occlusions in a blood vessel, said guidewire comprising: a core wire, said core wire terminating in a flexible distal end, said core wire extending along the length of said guidewire, the distal end of said core wire forming a gauging section, the diameter of said core wire being less at the gauging section than elsewhere on said core wire; a proximal marker, a distal marker and at least one intermediate marker disposed between said proximal and distal markers, each of said markers being radiopaque and linearly disposed on said gauging section, the outer diameters of said markers being 4b equal to or less than the diameter of any part of said core wire, and a helical coil of radiotransparent flexible wire surrounding said distal end including the gauging section of said core wire and said markers.
Brief Description of the Drawing Figure 1 is a side elevational view, partially in cross-section of a guidewire in a plastic jacket according to one embodiment of the present invention. The view shows the disposition of radiopaque markers on a core wire in the guidewire.
Figure 2 is a view of another embodiment of the device according to the present invention.
Description of the Preferred Embodiment Referring to Figure 1 of the drawing, a core wire 5 is shown with a distal end that forms a gauging section 5c which is necked down or tapered from a larger diameter body section 5a to the smaller diameter section 5c. The reduction in diameter is provided at a necked down section 5b. The diameter of the body section 5a of core wire 5 is about 0.020" and the diameter of the gauging section 5c is between about 0.002 to 0.006" with 0.004" being preferred.

~'O 93/08862 PCf/~1592/09073 -5- Nd~~z~~~~'~
An series of radiopacyue rings which serve as markers 11 is disposed on the gauging section 5c of the core wire 5.
These radiopaque markers 11 are made as described above and are arranged in a predetermined spaced relationship to each other and also relative to a distal marker 11A and a proximal marker 11B. The distal marker 11A and the proxi-mal marker 11B can be of a construction that is identical to the other markers, differing only by their positions on the core wire 5 and that they are fixedly attached thereto. The distal marker 11A and the 30 proximal marker 11B are each attached to the gauging section 5c and the' tapered section 5b of the core wire with a suitable adhe-sive or weld. The intermediate markers 11, that is those between distal marker 11A and proximal marker 118, are not attached to the core wire and serve as supports for an arrangement of helical coils 8 which are disposed between them. The markers 11 are spaced from each other by one centimeter or by such other spacing as desired.
In the embodiment of this Figure, the co o s 8 'are formed of flexible wire coils which are preferably made of single layer windings of a suitable radiotransparent mat-erial such as stainless steel. The wire of the coils 8 has a diameter less than about 0.0075°'. The outer diame-ter of the coils 8 is preferably less than about 0.045".
As shown, the markers 21 of this embodiment. also have an outer diameter of about 0.045'° and the coils 8 are about 1 cm. long whereby to hold the coils 8 between 'them at spac-ings of 1 cm. Since the distal marker 11A and the proxi-mal marker 11B are attached to the gauging section 5c and the tapered section 5b respectively of the core wire, the markers il disposed therebe~tween are held in place at 1 cm. intervals, but can shift about somewhat because of the w flexibility.of the coils 8 so as to compensate for the twists and turns the device will take while it is being inserted into a vessel.
The markers, the core wire and the coils are disposed within a radiotransparent jacket 30 that includes a dis-talmost hemispherical tip 31. The jacket 30 covers the entire assembly which includes the core wire, the coils 8 wo ~3ioss~z ~c~rius~zio~o~3 -h-and the markers 11 to encapsulate that entire assembly 21.
The jacket 30 can be heat formed (shrunk) over the entire assembly to encapsulate it. The jacket 30 can be made from any of the well knawn soft, biocompatible plastics used in the catheter art such as Percuflex, a trademarked v plastic manufactured by Eoston Scientific Corporation of Watertown Massachusetts. The wall thickness of -the jacket 30 can be between about .003'" and .008". When the catheter is inserted into a patient, the distal marker 11A
will be identifiable in an X-ray, as will each of the other markers in the assembly. They can be formed of the well known radiopaque materials such as gold, platinum or tantalum.
Referring to Figure 2 of the drawing, a guidewire assembly 1 is shown which includes a radiopaque tip 3.
The tip 3 has a hemispherical shape and is formed of a radiopaque material such as platinum or gold. Tip 3 has a flat inner surface 4 which establishes a reference point for the array of markers 11, as will be discussed Herein--after.
The distal end of a coil 7 is attached to the periphery of the inner surface 4 of the tip 3 by welding, braising or soldering. The proximal end of the coil 7 is joined to a plastic jacket 9 also by welding or an adhesive, which jacket 9 is heat shrunk to the core wire 5a.
In this embodiment, the dimensions and the shape of the care wire 5 are the same as has been described above.
~.s with the embodiment of Figure 1, an array of radio-paque markers 11 are disposed upon the gauging section 5c 30. of the core wire 5. These radiopaque markers 11 are .
arranged in a predetermined spaced relationship to each other and also relative to the inner surface 4 of 20 tip 3. The markers 11 are spaced from each other by about one centimeter and the spacing between the distal end of core wire 5 and the first radiopaque marker 11 is also about one centimeter. Other appropriate spacings may be estab-lished, as desired. Each of the markers 11 can be dis-posed on 'the gauging section 5c with an adhesive, or by welding, soldering or braying: Alternatively, for exam-~'O 93/08862 PCT/~1592/~9073 ~'~~~u~~~''~

ple, the markers can be made by metallurgically plating successive layers on the gauging section 5c as coatings until the desired ring 'thickness is attained.
In this embodiment, the outer annular peripheral sur-faces of the markers 11 are free 9:.o move within the inside of the coil 7. The inner and outer diameters of the packet 9 approximate the inner and outer diameters of the coil 7.
If desired with either of the ~:mbodiments, the spaces between the markers 11 can be filled with a flexible, rub-bery material to help keep 'the markers in place. Exem-plary of the rubbery materials that can be used are latex or urethane. Disposition of the rubbery material in bet-ween the markers can be accomplished by techniques well known to the art.
It is apparent that modifications and changes may be made within the spirit and scope of the present invention.
Tt is our intention, however only to be limited by the scope of the appended claims.
As our invention we claim.

Claims

CLAIMS,

1. A fluoroscopically viewable guidewire for a catheter to measure the size and shape of occlusions in a blood vessel, said guidewire comprising:
a core wire having a flexible distal end formed of a body section which tapers into a gauging section;
a proximal marker means, a distal marker means and at least one intermediate marker means, each of said marker means being radiopaque and linearly disposed on said gauging section, said marker means being spaced from each other at a predetermined distance; and a helical coil of radiotransparent flexible wire surrounding at least the gauging section of said core wire.

2. The guidewire according to claim 1 wherein said marker means are rings disposed on said gauging section of said core wire, said rings having outer diameters that are no greater than the diameter of said body section of the core wire.

3. The guidewire according to claim 2 wherein the diameter of the core wire in the gauging section is less then about half the diameter of the core wire in the body section.

4. The guidewire according to claim 1 wherein spaces between the marker means are filled with a flexible rubbery mass.

5. A fluoroscopically viewable guidewire for a catheter to measure the size and shape of occlusions in a blood vessel, said guidewire comprising:
a core wire having a flexible distal end formed of a body section tapering into a gauging section;

a proximal marker ring, a distal marker ring and at least one intermediate marker ring disposed between said proximal and distal marker rings, each of said marker rings being radiopaque and linearly disposed on said gauging section, the diameter of said marker rings being substantially the same as the diameter of said body section, said marker rings being spaced from each other at predetermined distances, and a helical coil of radiotransparent flexible wire surrounding at least the gauging section of said core wire.

6. The guidewire according to claim 5 wherein the diameter of the core wire in the gauging section is less then about half the diameter of the core wire in the body section.

7. A fluoroscopically viewable guidewire for a catheter to measure the size and shape of occlusions in a blood vessel, said guidewire comprising:
a core wire, said core wire terminating in a flexible distal end, said core wire extending along the length of said guidewire, the distal end of said core wire forming a gauging section, the diameter of said core wire being less at the gauging section than elsewhere on said core wire;
a proximal marker, a distal marker and at least one intermediate marker disposed between said proximal and distal markers, each of said markers being radiopaque and linearly disposed on said gauging section, the outer diameters of said markers being equal to or less than the diameter of any part of said core wire, and a helical coil of radiotransparent flexible wire surrounding said distal end including the gauging section of said core wire and said markers.

8. The guidewire according to claim 7 wherein spaces between the markers is filled with a flexible rubbery mass.

9. The guidewire according to claim 7 wherein the gauging section of said core wire is truncated to less then about half the diameter of the guidewire so as to receive said markers.