WO2003086522A1

WO2003086522A1 - A guidewire for guiding a catheter

Info

Publication number: WO2003086522A1
Application number: PCT/NL2003/000296
Authority: WO
Inventors: Nicolaas Hylke Bakker
Original assignee: Technische Universiteit Delft
Priority date: 2002-04-18
Filing date: 2003-04-17
Publication date: 2003-10-23
Also published as: AU2003224506A1; NL1020427C2

Abstract

The invention relates to a guidewire suitable for guiding a catheter into an occluded blood vessel, comprising a torsionally rigid shaft having a proximal end and a distal end, and on the distal end of the shaft there is an elongated flexible body, designed to follow the course of the blood vessel, which body retains its shape when during use the guidewire is subjected to a pushing load, wherein the distally oriented head of the flexible body is provided with a flexible trailer wire, which during use follows the flow in the blood vessel.

Description

A GUIDEWIRE FOR GUIDING A CATHETER

The invention relates to a guidewire suitable for guiding a catheter into an occluded blood vessel, comprising a torsionally rigid shaft having a proximal end and a distal end, and on the distal end of the shaft there is an elongated flexible body, designed to follow the course of the blood vessel, which body retains its shape when during use the guidewire is subjected to a pushing load.

Such a guidewire is known from the American patent specification US-A-5 184 621. The elongated flexible body of this known guidewire has a diameter of less than 0.020 inches.

The known guidewire is used for guiding a catheter required for the treatment of an occluded blood vessel. Such an occlusion in a blood vessel, stenosis, causes an undesir- able reduction in blood flow to the underlying tissue. To treat the stenosis, the occlusion may be dilated with the aid of a balloon catheter or by placing a stent with the aid of a catheter. For this purpose the balloon or stent needs to be placed completely in the occlusion. In order to be able to insert the catheter into the occlusion, the known guidewire is first inserted through the occlusion which subsequently serves as a guide over which the catheter that has a lumen for the guidewire, is fed.

There are two factors that make passing the occlu- sion with the guidewire more difficult: inadequate steerabil- ity and limited observability. The guidewire has a long flexible and torsionally rigid shaft whose distal end is provided with an elongated flexible body. By turning the proximal side of the guidewire, outside the body, the direction of the flexible body can be changed. By pushing at the proximal side, the guidewire is inserted further into the body. The guidewire has to be flexible enough to be able to follow small bends without damaging the vascular wall. The great flexibility and the considerable length make it difficult to manipulate the distal body of a guidewire into the desired direction, and the friction with the vascular wall adds to this difficulty. The guidewire will have the tendency to come to rest against a side wall of the vessel as a result of which it will not arrive at the opening of the stenosis.

The above-mentioned observability constitutes a sec- ond limitation when passing a stenosis. In order to be able to see the guidewire, the patient has to be X-rayed. The resulting image is shown on a monitor. This image is a 2-D projection, which allows poor insight into the 3-D anatomy of the stenosis. It is therefore not always clear where the opening in the occlusion is located. In addition, the resolution of the image is limited.

It is the object of the invention to improve the known guidewire such that the above-mentioned problems are reduced^" or eliminated. To this end the guidewire according to the invention is characterised in that the distally oriented head of the flexible body is provided with a flexible trailer wire, which during use follows the flow in the blood vessel. When advancing the guidewire, the flexible trailer wire will go with the flow to seek the passage in the occlusion, since the flow through the passage in the occlusion is in any case still present. The flexible trailer wire exerts a pulling force derived from the surrounding flow on the guidewire, such that the guidewire in its entirety becomes oriented toward the passage in the occlusion of the blood vessel. The guidewire according to the invention is therefore more often capable of passing through a stenosis. An important advantage of the guidewire according to the invention is that with serious occlusions or with occlusions in awkward places, the procedure for passing the stenosis is simplified because the guidewires need to be changed less often during the procedure. This limits the duration of treatment and also the material consumption. A further important advantage is that more stenoses can be treated by means of balloon catheterisation or by the placement of stents, so that the necessity of an open- (heart) surgery as the only remaining alternative also occurs less often. The guidewire according to the invention is especially well able to meet the objectives, when the same is preferably characterised in that the guidewire has a diameter of maximally approximately 10% of the diameter of the flexi- ble body. The extreme flexibility of this trailer wire is directly associated with this strongly reduced diameter of the trailer wire in relation to the flexible body.

In order to further optimise the trailing nature of the trailer wire with respect to the flow, it is advantageous for the trailer wire to possess a thickening at its distal end. Incidentally, it is generally remarked that the trailer wire may also have a constant diameter or may taper, with the diameter reducing in the direction of the distal end, or the diameter may become increasingly smaller over a number of discrete steps.

For the further optimisation of the flow-following nature of the trailer wire it is desirable for the same to be embodied, in a friction material. For example, it would be feasible to make the trailer wire from a suitable synthetic material, e.g. nylon. Alternatively, the trailer wire may be provided with a coating that increases friction.

The invention will now be further elucidated with reference to the drawing. The drawing shows in:

- Fig. 1 a schematic view of the distal end of the guidewire according to the invention in a first embodiment, and

- Fig. 2 a schematic view of the embodiment of the guidewire shown in Fig. 1 in addition to several possible other embodiments. Identical reference numbers in the figures refer to similar parts.

The embodiment of a guidewire as used for guiding a catheter is generally known and requires no further explanation. In the figures therefore, only a portion of the guidewire is shown, namely the part that during use is located in the body of a patient to be treated, and more in particular the distal end of such a guidewire. With reference first to Fig. 1, a portion of the torsionally rigid shaft 2 of such guidewire 1 is shown, which shaft 2 is at its distal end provided with an elongated flexible body 3. In the case shown, this elongated flexible body 3 is embodied as a helical spring. When during use a pushing load is exerted on the guide wire 1 from the proximal end, that is to say from outside the body of the patient to be treated, the shaft 2 and the elongated flexible body 3 attached thereto retain their shape. Fig. 1 further shows that in accordance with the invention a (very) flexible trailer wire 5 is provided to the distally oriented head 4 of the flexible body 3. This trailer wire 5 is designed such that when in use, it will go with the flow irr the blood vessel. The diameter of the trailer wire 5 is preferably at most approximately 10% of the diameter of the flexible body 3. For example, in the case shown the flexible body 3 has a maximum diameter of 0.356 mm, while the distal end of the trailer wire 5 near its free end has a diameter of 0.02 mm. Fig. 2 shows several possible variations of the embodiment indicated with the letters a, b, c and d. Variant ^Λc' shown in Fig. 2 corresponds to the embodiment of the guidewire according to the invention shown in Fig. 1. The two variants a and b of the embodiment shown in Fig. 2 exhibit the trailer wire 5 with a thickening 6 at its distal end. This promotes the flow-following nature of the trailer wire 5, and increases the pulling force exerted on the guide wire.

The variant indicated with d' shown in Fig. 2, finally, illustrates that the trailer wire 5 may also be embodied completely straight, that is to say different to the variants a, b, c, which are provided with a trailer wire 5 that is formed so as to substantially taper from the head 4.

Claims

1. A guidewire (1) suitable for guiding a catheter into an occluded blood vessel, comprising a torsionally rigid shaft (2) having a proximal end and a distal end, and on the distal end of the shaft (2) there is an elongated flexible body (3) designed to follow the course of the blood vessel, which body (3) retains its shape when during use the guidewire (1) is subjected to a pushing load, characterised in that the distally oriented head (4) of the flexible body (3) is provided with a flexible trailer wire (5) , which dur- ing use follows the flow in the blood vessel.

2. A guidewire according to claim 1, characterised in that the trailer wire (5) has a diameter of maximally approximately 10% of the diameter of the flexible body (3) .

3. A guidewire according to claim 1 or 2, character- ised in that the trailer wire (5) possesses a thickening (6) at its distal end.

4. A guidewire according to one of the preceding claims, characterised in that the trailer wire (5) is embodied in a friction material.

5. A guidewire according to one of the preceding claims, characterised in that the trailer wire (5) is provided with a coating that increases friction.