The invention relates to a guide wire comprising a core which extends from a proximal to a distal end of the guide wire and which is designed as a single part or from multiple longitudinal sections adjoining one another, and comprising a distal cladding which surrounds the core in a distal section and is made from a polyurethane material or another soft-flexible, i.e. soft-bendable, plastic material.
Such guide wires are used in particular in medical instruments, and specifically in catheter instruments. Boston Scientific Corp. offers a guide wire for such applications under the trade name of Jagwire®, which has a 5 cm long soft-flexible distal end section with a hydrophilic coating and the remaining proximal shaft section is designed to be stiffer and is provided with a black and yellow helical pattern for improved endoscopic visualization.
It is well-known to design a distal end section of a guide wire to be more flexible than the remaining proximal shaft section by tapering the wire core in this distal end section, i.e. by decreasing the diameter of said wire core, for example by using one or more axially adjacent conical taperings, with the core for example being composed of a super-elastic Ni/Ti material. This tapered distal core section is often surrounded by a distal cladding in the form of a helical spring, at the distal end of which a, for example, hemispherical end cap may be attached and the proximal end of which helical spring is attached to the wire core, for example in a diameter-reduced region of the latter, or to a proximally adjoining, different core cladding. Alternatively, the helical spring cladding can also extend continuously to the proximal end of the guide wire. The published patent applications WO 88/04940 A1 and WO 03/072179 A1, as well as patents U.S. Pat. No. 4,456,017, U.S. Pat. No. 5,456,732, DE 101 38 953 B4 and EP 0 714 315 B1 are mentioned as representatives of this prior art with distal helical spring cladding of the core.
The invention is based on the technical problem of providing a guide wire of the type mentioned initially which can be produced with relatively little effort and has a desired flexural behavior, in particular a particularly soft-flexible distal section connected to a significantly stiffer proximal shaft section if required.
According to the invention, in a distal section of the guide wire, the core is surrounded by a distal cladding made from a polyurethane material or another soft-flexible plastic material. This makes it possible for the corresponding distal section of the guide wire to have a very low stiffness if required. To this end, the core itself can also be designed to be more flexible in this distal section than in the section of the core proximally adjacent thereto, for example by correspondingly weakening the material and/or a corresponding choice of material.
According to one aspect of the invention, the wire core remains unclad in a region proximally adjoining the distal cladding, i.e. the surface of the guide wire in this region is formed by the core itself or, if need be, by a coating applied thereto.
According to a further aspect of the invention, the distal cladding is adjoined proximally by a tube cladding made of polytetrafluoroethylene (PTFE) or another plastic material with a similar stiffness and hence with a significantly higher stiffness than the distal cladding. The tube surrounds the core on all sides, contacts the latter, and has an enlargement on its distal end by means of which it surrounds a diameter-reduced proximal end region of the distal cladding and terminates, substantially flush in terms of the external diameter, on an annular shoulder of the distal cladding. This design measure allows a good connection of the more flexible distal cladding and stiffer proximally adjoining cladding of the core as well as a smooth external transition between the two claddings without abrupt steps. This can advantageously be aided by locating this transition region in a section of the core in which the latter is tapered.
According to a further aspect of the invention, a helical spring serves as the connection cladding of the core and proximally adjoins the distal cladding. This variation can likewise be implemented with advantageous properties regarding the flexural behavior of the guide wire and the connection of the two claddings, as well as the smooth external transition between the latter. Additionally, very flexible adjustment of the stiffness profile in the transition between the region of the distal cladding and the region of the proximally adjoining cladding is possible by appropriately designing the helical spring.
In a development of the invention, in a distal region, the core is designed to have constant stiffness or a stiffness which decreases stepwise in the direction of the distal end; this contributes to designing the guide wire to be more flexible in the distal end section than in the remaining region. In particular, this can be implemented by a corresponding continuous, in particular conical, or stepwise reduction of the diameter of the core, for example by abrading the latter. In this case, this diameter-reduced distal region of the core does not have to correspond precisely to the axial extent of the distal cladding.
In a development of the invention, the distal cladding is designed as a solid cladding which contacts the core on all sides and embeds the latter, and which forms a blunt distal guide wire end at its distal end and/or the proximal end region of which terminates with a stepwise reduction in diameter or with a diameter which continuously decreases over a predeterminable axial length. The former measure makes an atraumatic, blunt distal end of the guide wire possible in a simple fashion, while the latter contributes to an optimum stiffness profile and a smooth external profile of the guide wire surface level with the proximal end region of the distal cladding.
In a development of the invention, the cladding which proximally adjoins the distal cladding extends up to the proximal end of the guide wire, or its proximal end terminates at a proximally adjoining unclad core region or at a proximally adjoining further cladding. In the first- mentioned case, the connection cladding forms the entire guide wire surface with the exception of the more flexible distal end region in which the distal cladding forms the guide wire surface.
In an advantageous refinement of the invention, the surface of the distal cladding is hydrophilic, for example as a result of applying a hydrophilic coating onto the distal cladding.
In a development of the invention, the proximal end region of the distal cladding and the distal end region of the connection cladding merge into one another with the external diameters substantially being flush at a punctiform transition point or within a transition region of a predeterminable length, i.e. the external diameter of the guide wire does not noticeably abruptly change in this region.
In an advantageous development of the invention, the cladding which proximally adjoins the distal cladding is formed by a helical spring and a distal end region of which is formed with a stiffness which continuously decreases in the direction of the distal end, for example. This makes it possible to set the stiffness profile of the guide wire in the transition between the soft-flexible distal end section and the stiffer adjoining shaft section in a desired manner; for example, it can be set to be continuously decreasing from the higher value in the shaft section to the lower value in the distal end section over a selectable axial length, with a steeper characteristic line over a shorter length or a shallower characteristic line over a greater length.
To this end, in a refinement of this measure, the distal end region of the helical spring is formed with a winding spacing which increases in the direction of the distal end and/or with a decreasing spring wire thickness. A wire thickness in distal end region which decreases in the direction of the distal end can be implemented in the helical spring, for example, by an abraded external region as effected by external conical abrasion. In a further refinement, the region of the helical spring which is abraded externally has an external diameter which decreases in the direction of the distal end or which remains constant with a correspondingly increasing winding diameter. The former is particularly simple from a production point of view; the latter makes it possible to keep the external diameter of the helical spring constant, even in this region of decreasing stiffness.
In a development of the invention, an enveloping section of the distal region of the helical spring surrounds a proximal end section of the distal cladding. This further contributes to a good connection between the distal cladding and the proximally adjoining, core-cladding helical spring and to a gradual transition of the stiffness property of the guide wire from the more flexible distal end section to the stiffer, proximally adjoining section with the helical spring.
In a development of the invention, the helical spring has an embedding section on the distal end with a smaller external diameter than the proximally adjoining helical spring section, with the embedding section of the helical spring section being surrounded by the distal cladding. This also contributes, in an advantageous manner, to a good connection between distal cladding and helical spring and to an optimization of the flexural behavior of the guide wire at the transition from the distal end section with lower stiffness to the proximally adjoining shaft section with higher stiffness. Here, reference is once again made to the fact that these measures and, to this end, the other abovementioned measures can additionally be accompanied by an appropriate design of the wire core, in particular a stepwise or continuous reduction of the diameter of the latter in its region surrounded by the distal cladding and/or already in the region which is axially level with the surrounding helical spring.
In a development of the invention, the helical spring acting as connection cladding is attached to the wire core at one or more axially spaced attachment sites. This reliably holds the helical spring in its intended position with respect to the core, for example in the case of shearing forces which act on the distal end region of the guide wire and can be transferred from the distal cladding onto the helical spring.
Advantageous embodiments of the invention are described below and illustrated in the drawings, in which:
a shows a longitudinal sectional view of a distal part of a guide wire with a soft-flexible distal cladding and an adjoining helical spring core cladding formed by a distally stretched helical spring,
b shows a longitudinal sectional view of the helical spring used for the guide wire of
a shows a partial longitudinal sectional view of a guide wire in accordance with
b shows a longitudinal sectional view of the helical spring used in the guide wire of
a shows a partial longitudinal sectional view of a guide wire in accordance with
b shows a longitudinal sectional view of the helical spring used in the guide wire of
c shows a longitudinal sectional view of the helical spring of
a shows a partial longitudinal sectional view of a guide wire in accordance with
b shows a longitudinal sectional view of the helical spring used in the guide wire of
a shows a longitudinal sectional view of a guide wire similar to that of
b shows a longitudinal sectional view of the helical spring used in the guide wire of
b shows a longitudinal sectional view of the helical spring used in the guide wire of
A guide wire shown in
In a distal end section with a predeterminable length of, for example, approximately 5 cm, the core 1 is surrounded by a distal cladding 2 of relatively soft-flexible plastic material which, in particular, can be a polyurethane material (PU material). Further soft-flexible plastic materials suitable for medical applications are, for example, nylon or the material known as Pebax. At its distal end 2a, the distal cladding forms a hemispherical, blunt and hence atraumatic distal termination of the guide wire.
A tube cladding 3 of the core 1 made of polytetrafluoroethylene (PTFE) proximally adjoins the soft-flexible distal cladding 2. This stiffer PTFE core cladding surrounds the core 1 up to and including its proximal end 1a whilst forming a rounded proximal end termination 3a. The PTFE core cladding 3 can, for example, be shrunk over the core 1 as a shrink tube and lies tight against the core 1, contacting it on all sides, even in a proximal part of its distal tapering region 1c, except for at an enlargement 3b of the PTFE cladding 3 at its distal end, as shown.
This distal end enlargement 3b of the PTFE cladding 3 is located in the tapering region 1c of the core 1 and butts, externally flush, against a corresponding annular shoulder 2c which is formed at the proximal end region 2b of the distal cladding 2. The material of the distal cladding 2 fills the intermediate space between the distal enlargement 3b of the PTFE cladding 3 and the core 1. This provides a good transition and a reliable connection between the soft-flexible distal cladding 2 and the proximally adjoining PTFE cladding 3, with it also being possible, as shown, to achieve a relatively smooth profile of the guide wire surface without abrupt steps, even in this transition region between the two claddings 2, 3.
It should be noted here that in this exemplary embodiment, and also in all other shown and described exemplary embodiments, the soft-flexible distal cladding 2 is preferably designed with a hydrophilic surface, for example by means of a hydrophilic coating 10 applied to the soft-flexible cladding material. The overall length of the wire core 1 and hence the guide wire can vary depending on the application and is typically between approximately 1 m and 5 m for medical applications, in particular in catheter instruments.
Hence, the exemplary embodiment of
In the following text, further advantageous variations of the guide wire are explained with reference to
Thus,
The helical spring 4 is additionally attached to the core 1 at an attachment site 6 in a region between its ends, for example by adhesive bonding. This attachment/bonding site 6 is located, for example, in the proximal shaft section which is still in the region of, or just behind, the conical tapering 1c of the core 1. The additional attachment of the helical spring 4 to the core 1 can absorb possible impact/compressive loads which act on the distal end of the guide wire during its use and which can be transferred to the helical spring 4 from the distal cladding 2.
The use of the helical spring 4 as connection cladding of the core 1 which proximally adjoins the soft-flexible distal cladding 2 can provide functional advantages and also advantages relating the to production complexity compared to, for example, the alternative use of a PTFE core cladding. Moreover, particularly the properties and advantages of the soft-flexible distal cladding 2, mentioned above in context of the examples of
From a manufacturing point of view, a helical spring as connection cladding also makes it possible to very flexibly set respectively desired flexural characteristics of the guide wire in a relatively simple manner. This will be explained in more detail below on the basis of various exemplary embodiments, as illustrated in
In this respect,
In this exemplary embodiment, as shown, the wire core 1 also tapers conically in a tapering region 1c which in this case extends over the region of the soft-flexible distal cladding 2 and, proximally, beyond the latter and which also extends over a distal part of the adjoining helical spring cladding 4. In line with the other exemplary embodiments, the conical tapering region 1c can, as required, comprise a single conical section or a number of successive conical regions which are directly adjacent to one other or are arranged at an axial distance from one another and have the same or different cone angles. It is furthermore understood that in this and in all other shown and described exemplary embodiments, the core 1 is formed as a single part which extends from its distal end 1b to its proximal end (not shown in
a also shows that, in this example, the external diameter of the helical spring 4 is selected to be substantially equal to the external diameter of the soft-flexible distal cladding 2 so that a homogeneous transition with a constant external diameter of the guide wire is achieved between the two different, adjacent core claddings 2, 4. In this case, the soft-flexible material of the distal cladding 2 extends, in the proximal end region of the latter, into the intermediate space between the core 1 and the surrounding distal end region 4c of the helical screw 4 and, in the process, also fills the gaps between successive spring windings located there as a result of the stretching of the spring; as a result of this, there are no interfering gaps in the transition between the two different core claddings 2, 4. The proximal end 2b of the distal cladding 2 terminates, as in the example of
As a result of the stretching, the stiffness of the helical spring 4 in the distal region 4c is correspondingly reduced continuously. As a result of this, a particularly homogeneous, gradual transition of the stiffness of the guide wire is achieved from a very soft-flexible distal end section, with the tapered core 1 and soft-flexible distal cladding 2, to the significantly stiffer proximally adjoining shaft section with the thicker core 1 and the helical spring core cladding 4 which is stiffer than the distal cladding 2. In other words, the stiffness of the guide wire does not abruptly change from the low value in the distal end region to the higher value in the proximally adjacent shaft section, but rather it changes gradually along the stretched distal spring end region 4c, with the axial length and its predeterminable flexural characteristics therefore substantially determining this stiffness transition of the guide wire.
a and 5b illustrate a variation of the guide wire of
As a result of the external conical abrasion, the stiffness of the distal end region 4c of the helical spring 4 decreases toward the distal end 4b in addition to the reduction in stiffness as a result of the stretching of the spring and so a particularly homogeneous or gradual stiffness transition of the guide wire is achieved overall from the low stiffness in the distal end section with the soft-flexible distal cladding to the higher value in the shaft section clad by the helical spring 4.
a, 6b and 6c illustrate another variation of the guide wire, in which the property of a constant guide wire external diameter, even in the transition region between the distal cladding 2 and the proximally adjacent helical spring cladding 4, as implemented in the example of
The helical spring 4 prefabricated in this way is then pulled over the core 1 and the distal end region 4c of this helical spring 4 is connected to the distally adjoining soft-flexible cladding 2, as shown in
a and 7b illustrate a variation of the guide wire which corresponds to the guide wire of
The transition region designed in this way clearly results in a particularly secure connection of soft-flexible distal cladding 2 and proximally adjoining helical spring cladding 4 of the central wire core 1 with a smooth, constant external diameter and a gradual stiffness transition from the low value in the distal section in front of the helical spring 4 to the higher value in the proximal shaft section with the helical spring 4.
a and 8b illustrate a variation of the guide wire according to the type of
The attachment/bonding site 6 is preferably still located in the rear part of the distal tapering section 1c of the core 1 or it is alternatively located in the shaft section with the constant wire core diameter lying behind said tapering section with preferably a small distance from the tapering region 1c. The rear, proximal end 4a of the helical spring 4 is attached to the proximal wire core end 1a at a further attachment/bonding site 8. The attachment/bonding means used here simultaneously form a hemispherical proximal termination cap 9 of this guide wire.
The individual illustration of
a and 9b illustrate a further exemplary embodiment of a guide wire which uses a helical spring 4 which is identical in its design to that of the exemplary embodiment of
As the different exemplary embodiments shown and explained above make clear, the invention provides an advantageous guide wire which has a very soft-flexible distal end region with a thin wire core and a soft-flexible plastic coating, preferably coated in a hydrophilic manner, and has a shaft section proximally adjoining thereto in which the interior wire core is surrounded by a helical spring or a specifically designed plastic tube in the distal end region, or in which the interior wire core remains unclad. The use of a helical spring for the connection cladding can be implemented in a comparatively cost-effective manner and allows for the profile of the stiffness of the guide wire in the transition region between the soft-flexible distal cladding and the proximally adjoining region to be controlled particularly well, as described above in the context of the appropriate exemplary embodiments. The invention is particularly suitable for guide wires in medical catheter applications, but also for all other applications, in which there is a need for such guide wires.
Number | Date | Country | Kind |
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10 2006 047 675.1 | Sep 2006 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2007/008057 | 9/17/2007 | WO | 00 | 10/28/2009 |