The present invention relates to a method for the placement of an intraluminal guidewire utilising blood flow, and to a guidewire for use in such a placement.

Background Art

The placement of prosthetic devices such as stents intraluminally and the conduct of operative procedures intraluminally has grown dramatically in recent years. In many of these placements and procedures, it is necessary to initially position a guidewire into a desired part of a desired blood vessel. Once an initial guidewire is in place a catheter or other tubular device may be positioned over the guidewire and used to convey another guidewire, a prosthesis, an endoscope or a surgical instrument into the desired blood vessel. There are a variety of techniques used to position guidewires intraluminally, however, there are often problems encountered by medical practitioners in achieving the desired placement of a guidewire. The present invention is directed to an alternative method for the intraluminal placement of a guidewire. Disclosure of the Invention

In a first aspect, the present invention consists in a longitudinal member that can be positioned in a blood vessel having at or adjacent a free end an inflatable or otherwise expandable flow impedance device that may be actuated externally of the lumen of the blood vessel into which that free end has been positioned and which is of such a size and shape that the flow impedance device will cause the longitudinal member to be drawn downstream through the vessel by blood flow therethrough.

The longitudinal member can comprise a guidewire or catheter. In preferred embodiments of the invention the flow impedance device comprises a balloon, preferably made of latex, that may be inflated to a size so that it will be guided by the blood flow without being large enough to catch against the walls of the vessel through which it is passing. In another embodiment the flow impedance device has the form of a small umbrella which may be at least partially opened to catch the flow of blood through the vessel and be guided and/or carried by that flow. In one embodiment, the inflatable or otherwise expandable flow impedance device

at or adjacent the free end of the catheter may be further expanded such that it engages with the walls of the vessel and holds the catheter at a desired position.

The flow impedance device may be actuated by a fluid, such as isotonic saline or gas, directed down a lumen in the guidewire or catheter or mechanically, such as by an even finer wire extending down that lumen. Alternatively, the inflation or opening of the device may be effected extracorporeally by magnetism, thermal energy, electromagnetic radiation or the like. The cross-sectional size of the flow impedance device will be determined by the vessel into which the guidewire is to be guided. In the aorta it may be as much as 10 mm. In other blood vessels it will be smaller and. in some cases, will be no more than 1 mm.

In a further aspect, the present invention consists in an assembly comprising a catheter and guidewire that can be positioned in a blood vessel, the guidewire having at or adjacent its free end an inflatable or otherwise expandable flow impedance device that may be actuated externally of the lumen of the blood vessel into which the free end has been positioned and wliich is of such a size and shape that the flow impedance device will cause the guidewire to be drawn downstream through the vessel by blood flow therethrough.

In one embodiment of this aspect, the catheter also has at or adjacent its free end an inflatable or otherwise expandable flow impedance device, such as a latex balloon or umbrella. In one embodiment of this further aspect, the flow impedance device at or adjacent the free end of the guidewire can comprise a solid bead. The bead may comprise a bead of epoxy resin or titanium of larger profile than the guidewire attached to the end of the guidewire.

According to a still further aspect, the present invention consists in a delivery catheter for placement in a blood vessel comprising:

(a) an elongate catheter having a first end and a second end;

(b) an intraluminal graft having a body disposed about the elongate catheter, the body having at a first end, disposed adjacent to the first end of the elongate catheter, a tubular portion, and at a second end a bifurcation into first and second tubular graft extensions, the

elongate catheter extending up the first tubular graft extension and into the tubular portion; and

(c) a supplementary guidewire extending in a first direction through the first tubular graft extension and projecting in a second different direction into the second of the tubular graft extensions, the guidewire having at or adjacent its free end an inflatable or otherwise expandable flow impedance device that may be actuated externally of the lumen of the blood vessel into which the free end has been positioned and which is of such a size and shape that the flow impedance device will cause the guidewire to be drawn downstream through the vessel by blood flow therethrough. ln one embodiment of this further aspect, the supplementary guidewire extends through a channel in the graft body. In another embodiment, a supplementary catheter can extend in the first direction through the first tubular graft extension and in the second different direction into the second tubular graft extension, the supplementary catheter containing the supplementary guidewire.

In this aspect, the elongate catheter can have an inflatable balloon at or adjacent one end and the intraluminal graft can be disposed about the balloon. In another embodiment, the first end of the intraluminal graft can be self-expandable.

In one embodiment of this aspect of the present invention, the supplementary catheter also has an inflatable or otherwise expandable flow impedance device at or adjacent its free end, such as a latex balloon or umbrella.

The first and second tubular graft extensions are each preferably adapted to engage with a further tubular graft that extends at least partially into different vessels branching off the vessel. In one embodiment, one of the tubular graft extensions can have an expanded diameter in the downstream direction thereby facilitating insertion of a guidewire into this tubular graft extension should that be desired. In a preferred embodiment of the invention, the intraluminal grafts that are positioned at least partially in the branching vessels are provided in varying diameters. This ensures that a suitable graft is available to meet the varying diameters of the branching vessels that are routinely operated upon in practice. In one embodiment, the variation in diameter of the intraluminal graft is achieved by a taper inwardly

or outwardly of the outside diameter along at least a portion of the length of the shaft. Alternatively, the change in diameter is provided by a shorter step- down or step-up taper between two substantially cylindrical portions of different diameter which constitute the graft. Preferably, the upstream ends of the intraluminal grafts are of a standard diameter so as to provide a reliable connection with the respective tubular graft extensions of the intraluminal graft positioned wholly within the vessel upstream of the branches in the vessel.

In a further aspect, the present invention consists in a method for positioning a longitudinal member, such as a guidewire or catheter, within a blood vessel or other bodily vessel, comprising the steps of introducing the longitudinal member into the blood or other bodily vessel upstream of where the free end of the longitudinal member is to be positioned, inflating or otherwise expanding a flow impedance device positioned at or adjacent a free end of the longitudinal member within the vessel and allowing the flow of blood through the vessel to draw the flow impedance device downstream through the vessel.

In yet a further aspect, the present invention consists in a method for positioning an assembly comprising a catheter and guidewire each having a free end within a blood vessel or other bodily vessel, comprising the steps of introducing the assembly into the blood or other bodily vessel upstream of where the free ends of the catheter and guidewire are to be positioned, inflating or otherwise expanding a flow impedance device positioned at or adjacent the free end of the guidewire within the vessel and allowing the flow of blood through the vessel to draw the flow impedance device downstream through the vessel.

In a still further aspect, the present invention consists in a method for positioning an intraluminal graft into a branching vessel within a patient's body, the vessel comprising a single pre-branching vessel branching into a pair of post-branching vessels, the method comprising:

(a) introducing into one of the post-branching vessels a first intraluminal graft having a body having at a first end a tubular portion and a second end that is bifurcated into first and second tubular graft extensions, there being positioned within the first intraluminal graft a guidewire wliich extends in a first direction through the first tubular graft extension and projects in a second

different direction into the second tubular graft extension, the guidewire having at or adjacent its free end an inflatable or otherwise expandable flow impedance device that may be actuated externally of the lumen of the post-branching vessel into which the free end has been positioned and which is of such a size and shape that the flow impedance device will cause the guidewire to be drawn downstream through the vessel by blood flow therethrough;

(b) positioning the first end of the first intraluminal graft and the second tubular graft extension within the pre-branching vessel and expanding that graft until at least the first end thereof expands into contact with a circumferential wall of the pre-branching vessel;

(c) inflating or otherwise expanding the flow impedance device positioned at or adjacent the free end of the guidewire and allowing the flow of blood through the vessel to draw the guidewire downstream to a desired position in the other of the post-branching vessels and then deflating the flow impedance device; and

(d) introducing a second intraluminal graft, having an upstream end and a downstream end, into the other of the post-branching vessels and, utilising the guidewire, or another guide positioned in its place, moving the second intraluminal graft until its upstream end is within or surrounds the second tubular graft extension and its downstream end is within the other of the post-branching vessels and causing the upstream end of the second intraluminal graft to form fluid conveying engagement with the second tubular graft extension. In a prefeπed embodiment of this aspect, a supplementary catheter can extend in the first direction through the first tubular graft extension and in the second different direction into the second tubular graft extension, the supplementary catheter containing the supplementary guidewire. In a preferred embodiment of this further aspect of the invention, the catheter also has al or adjacent its free end an inflatable or otherwise expandable flow impedance device and wherein in the method prior to step (c) the flow impedance device on the catheter is inflated or otherwise expanded to allow the flow of blood through the vessel to draw the catheter downstream to a desired position in the other of the post-branching vessels and then, once the catheter is in the desired position, the flow impedance device is deflated.

Once the catheter is in the desired position in the other of the post- branching vessels, the flow impedance device preferably can be further expanded so that it can engage with the wall of the other of the post- branching vessels and hold the catheter at the desired position. In a preferred embodiment of this aspect, the method can further comprise the step of:

(e) introducing a third intraluminal graft, having an upstream end and a downstream end, into the one post-branching vessel and moving the third intraluminal graft until its upstream end is within or surrounds the first tubular graft extension and its downstream end is within the one post-branching vessel and causing the upstream end of the third intraluminal graft to form fluid conveying engagement wilh the first tubular graft extension.

In a further embodiment of this aspect, the steps of introducing the first intraluminal graft into one of the post-branching vessels and positioning the upstream end and the second tubular graft extension within the pre- branching vessel can comprise:

(a) guiding a delivery catheter, which has a uninflated balloon adjacent one end with the first end of the first intraluminal graft disposed about the balloon, over a smaller diameter guidewire and within a larger diameter catheter sheath pre-positioned in the one post-branching vessel and pre-branching vessel;

(b) partially withdrawing the catheter sheath to free the first intraluminal graft; (c) inflating the balloon and so expanding the first end of the first intraluminal graft until it engages against the pre-branching vessel wall: and

(d) deflating the balloon. In a still further embodiment of this aspect, the steps of introducing the second intraluminal graft into the other of the post-branching vessels and moving it upstream until its upstream end is within the second tubular graft extension can comprise:

(a) guiding a second delivery catheter, which has an uninflated balloon adjacent one end with the upstream end of the second intraluminal graft disposed about the balloon, over a guidewire and

within a larger diameter catheter sheath pre-positioned in the other post-branching vessel and the pre-branching vessel; (b) partially withdrawing the catheter sheath to free the second intraluminal graft; fc) inflating the balloon and so expanding the upstream end of the second intraluminal graft until it engages against the second tubular graft extension;

(d) maintaining the inflation of the balloon while withdrawing the first delivery catheter from the one post-branching vessel; and (e) once the first delivery catheter is removed from the one post- branching vessel deflating the balloon.

In yet a still further embodiment, the steps of introducing the third intraluminal graft into the one post-branching vessel and moving it upstream until its upstream end is within the first tubular graft extension can comprise:

(a) guiding a third delivery catheter, which has an uninflated balloon adjacent one end with the upstream end of the third intraluminal graft disposed about the balloon, over a smaller diameter guidewire and within a larger diameter catheter sheath pre- positioned in the one post-branching vessel and the pre-branching vessel;

(b) partially withdrawing the catheter sheath to free the third intraluminal graft;

(c) inflating the balloon and so expanding the upstream end of the third intraluminal graft until it engages against the first tubular graft extension; and

(d) deflating the balloon.

In a still further aspect, the present invention consists in a method for posilioning an intraluminal graft across an aneurysm which extends from the aorta into at least one iliac artery within a patient's body, the method comprising the steps of:

(a) making an incision or puncture to expose one of the patient's femoral arteries:

(b) inserting a first guidewire through the exposed femoral artery, the corresponding iliac artery and the aorta such that it traverses the aneurvsni;

(c) guiding a first catheter sheath over the first guidewire until it traverses the aneurysm;

(d) withdrawing the first guidewire;

(e) inserting a second relatively stiff guidewire through the first catheter sheath until it traverses the aneurysm;

(f) withdrawing the first catheter sheath;

(g) guiding a second relatively larger diameter catheter sheath over the second guidewire until it traverses the aneurysm;

(h) guiding a first delivery catheter, which has an uninflated balloon adjacent one end with a first intraluminal graft disposed about the balloon, over the second guidewire and within the second larger diameter catheter sheath, the first intraluminal graft having a body having at a first end a tubular portion and a second end that is bifurcated into first and second tubular graft extensions, there being positioned within the first graft a third catheter containing a third guidewire which extends in a first direction through the first tubular graft extension and in a second different direction into the second tubular graft extension, the third guidewire having at or adjacent its free end an inflatable or otherwise expandable flow impedance device that may be actuated externally of the lumen of the other iliac artery into which the free end has been positioned and which is of such a size and shape that the flow impedance device will cause the third guidewire to be drawn downstream through the other iliac artery by blood flow therethrough; (i) positioning the first delivery catheter so that the first end of the first graft is upstream of the aneurysm;

(j) partially withdrawing the second larger diameter catheter sheath to free the first intraluminal graft; (k) inflating the balloon and so expanding the first end of the first intraluminal graft until it engages against the wall of the aorta above the aneurysm;

(1) deflating the balloon which allows blood to flow down the first graft distending the first and second tubular graft extensions; (m) inflating or otherwise expanding the flow impedance device positioned at or adjacent the free end of the third guidewire and allowing the flow of blood through the other iliac and femoral arteries

to draw the third guidewire downstream to a desired position in the other femoral artery and then deflating the flow impedance device;

(n) making an incision or puncture and retrieving the third guidewire from the other femoral artery; (o) withdrawing the third catheter through the one femoral artery;

(p) guiding a fourth catheter sheath over the third guidewire and through the other femoral and iliac arteries until it is within the first graft and reaches at least to the top of the second tubular graft extension: (q) withdrawing the third guidewire through lhe one femoral artery;

(r) guiding a fourth relatively large diameter guidewire through the fourth catheter sheath until the guidewire reaches at least the top of the second tubular graft extension;

(s) withdrawing the fourth catheter sheath through the other femoral artery;

(t) guiding a fifth relatively larger diameter catheter sheath over the fourth guidewire until the fifth catheter sheath reaches at least the top of the second tubular graft extension;

(u) guiding a second delivery catheter, which has a uninflated balloon adjacent one end with a second intraluminal graft, having an upstream end and a downstream end, disposed about the balloon. over the fourth guidewire and within the fifth larger diameter catheter sheath until the upstream end of the second graft is within the second tubular graft extension: (v) partially withdrawing the fifth catheter sheath to free the second intraluminal graft;

(w) inflating the balloon on the second delivery catheter and so expanding the upstream end of the second intraluminal graft until it engages against the second tubular graft extension; (x) maintaining the inflation of the balloon while withdrawing the first delivery catheter from the one femoral artery;

(y) once the first delivery catheter is removed from the one femoral artery deflating the balloon;

(z) fully withdrawing the fifth catheter sheath through the other femoral artery;

(aa) guiding a third delivery catheter, which has an uninflated balloon adjacent one end with a third intraluminal graft, having an upstream end and a downstream end, disposed about the balloon, over the second guidewire and within the second catheter sheath until the upstream end of the third graft is within the first tubular graft extension;

(bb) partially withdrawing the second catheter sheath to free the third intraluminal graft;

(cc) inflating the balloon on the third delivery catheter and so expanding the upstream end of the third intraluminal graft until it engages against the first tubular graft extension;

(dd) deflating the balloon on the third delivery catheter;

(ee) withdrawing the second delivery catheter through the other femoral artery and the third delivery catheter through the one femoral artery;

(ff) withdrawing the fourth guidewire and the fifth catheter sheath through the other femoral artery and suturing the incision or puncture in that artery; and

(gg) withdrawing the second guidewire and second catheter sheath through the one femoral artery and suturing the incision or puncture in that artery.

As an alternative to step (1), the first and second tubular graft extensions can be distended respectively by an inflatable balloon or are self- expandable. In a preferred embodiment of this still further aspect of the invention, the third catheter has at or adjacent its free end an inflatable or otherwise expandable flow impedance device and wherein prior to step (m) the flow impedance device on the catheter is inflated or otherwise expanded to allow the flow of blood through the vessel to draw the catheter downstream to a desired position in the other of the post-branching vessels and then, once the catheter is in the desired position, the flow impedance device is deflated.

Once the third catheter is in the desired position in the other iliac artery, the flow impedance device can preferably be further expanded so that it can engage with the wall of the other iliac artery and hold the third catheter at the desired position until it is necessary to withdraw the third catheter.

The catheter and method according to this invention preferably utilise balloon expandable grafts made according to the disclosure of Australian Patent Application No 78035/94, the contents thereof are incorporated herein by reference. Other suitable balloon expandable or self- expandable stents or grafts could be used in carrying out the present invention.

The method and longitudinal member according to the present invention may be used to position a guidewire in any artery or vein of sufficient size which is patent and has blood flowing through it. Obviously placement can only be in a downstream direction in so far as the flow directed part of the placement is concerned. A guidewire according to this invention may, however, be deployed from an end of a sheath or catheter which has been inserted into the body, intraluminally or otherwise. It is possible that in such a situation the sheath or catheter may be directed vipstream through a first vessel and the guidewire is then deployed to be flow directed downstream through another vessel branching from the first.

The present invention is hereinafter described with reference to the placement of a delivery catheter in an artery, which is a typical application. The invention is. however, also useful in placing a delivery catheter in another bodily vessel such as a vein.

Brief Description of the Drawings

Fig. 1 is a diagrammatic partially cut-away central view of a patient with an aortic aneurysm which has been bridged by an intraluminal graft according to the present invention; Fig. 2 is a side elevational view of one embodiment of a tubular intraluminal graft for use in the method described with reference to Fig. 1:

Fig. 3 is a longitudinal diametric sectional view through the intraluminal graft of Fig. 2;

Fig. 4 is a detailed elevational view of one end of the intraluminal graft of Fig. 2;

Fig. 5 is a detailed perspective view of the first end of the intraluminal graft of Fig. 4 showing how the alternate crests of the end wire of the graft are pushed radially outward during insertion of the graft;

Figs. 6 and 6a are vertical sectional views of two embodiments of possible bifurcated grafts mounted over delivery catheters for use in carrying out the present method;

Fig. 6b is an enlarged view of the inflatable balloons adjacent respectively the free end of a catheter and a guidewire with the balloons inflated;

Fig. Gc is a longitudinal sectional view of the device of Fig. 6b with the balloons uninflated;

Fig. 6d is a simplified sectional view of a guidewire having an expandable umbrella adjacent its free end;

Fig. 6e is a simplified side elevational view of a guidewire having a solid bead at its free end; Figs. 7a to 7i show the stages of carrying out one method according to the present invention;

Figs. 8a to 8f are simplified side elevational views of alternative intraluminal grafts for use in the method according to the present invention; and Fig. 9 is a vertical sectional view of one embodiment of a tubular graft mounted over a delivery catheter that can be used in carrying out the present invention. Preferred Mode of Carrying out the Invention

A bifurcated or trouser graft comprising the three intraluminal grafts 10, 10a and 10b is adapted for insertion transfemorally into a patient to achieve bridging and occlusion of an aortic aneurysm extending into the left iliac artery. As is seen in Fig. 1 the aorta 11 is connected to the left and right iliac arteries 13,12. The aortic aneurysm is located between the renal arteries 14 and 15 and the iliac arteries 12 and 13 with the aneurysm extending down the left iliac artery 13.

Each intraluminal graft (as is shown in Figs. 2-5) can comprise a crimped tube 16 of woven polyester. The grafts can be fabricated from other materials including polytetrafluoroethylene, polyurethane or a composite thereof. The tube 16 is reinforced along its length by a number of separate and spaced apart stainless-steel wires 17 (each of which can have the depicted generally closed sinusoidal shape). The wires 17 are preferably as thin as possible and are typically 0.3 to 0.4 mm in diameter. The wires 17 are malleable and may be bent into any desired shape, ie Ihey are not resilient to any substantial extent so that they have to be physically expanded into contact with the aorta rather than expanding by virtue of their own resilience. The wires 17 are each woven into the fabric of the tube 16

such that alternate crests of each wire 17 are outside the tube 16 with the remainder of that wire 17 inside the tube (except in the case of the endmost wires as will be hereinafter described). The ends of each wire 17 are located outside the tube 16 and are twisted together to form a tail 18. The tails 18 of alternate wires 17 are bent to extend in opposite longitudinal directions along the outside surface of the tube 16.

The endmost wires 17a overhang the respective ends of the tube 16 so that alternate crests of those wires 17a extend longitudinally beyond the end of the tube 16. The endmost wires 17a preferably have an amplitude of about 6 mm and a wavelength such that between six and eight crests are spaced around the circumference of a 22 mm diameter graft. The next two adjacent wires 17 preferably are spaced as close as possible to the endmost wire 17a and respectively have amplitudes of 4 mm and 5 mm. These wires will typically have the same wavelength initially as the wire 17a. Thereafter, throughout the graft 10 the wires 17 are spaced at 15 mm intervals, have an amplitude of 6 mm. and have substantially the same initial wavelength as the endmost wire 17a.

As the aneurysm extends beyond the branching of the iliac arteries 12 and 13 from the aorta 11 a single tubular graft is insufficient to bridge the aneurysm while maintaining blood flow to each of the iliac arteries 12 and

13. Rather than using a single tubular graft, in the present method three separate grafts 10, 10a and 10b are used. The downstream end of a first one of the grafts 10 is provided with a bifurcation to form a pair of short tubular extensions 19 of the graft 10. The short tubular extensions 19 may be passively expandable by blood flow or actively expandable by balloon expansion or by spring self-expansion.

As is best depicted in Figs. 8(a) - (f). the graft portions 10a and 10b which are adapted to extend into the respective iliac arteries 12, 13 each have an upstream end having a common diameter. The upstream ends interlock with the respective extensions 19a, 19b of the graft 10 adapted to be positioned within the aorta. Preferably, this interlocking is achieved by balloon-expansion or spring self-expansion of the upstream ends such that there is a frictional engagement between the respective upstream ends and the extensions 19a. 19b. In addition to having a straight cylindrical tube, the diameter of the downstream end 35 of the graft portions 10a and 10b can be provided in

varying diameters so as to suit the diameter of the iliac artery into which graft portions 10a and 10b are being implanted.

The change in diameter can be provided by a short step-down portion 31 (see Fig. 8c) or a step-up portion 32 (see Fig. 8d) or by a region of taper 33 and 34 extending along a length of the graft portion 10a or 10b (see Figs. 8e and 8f).

The method for positioning the intraluminal graft will now be described with particular reference to Figs. 7a - 7i. In carrying out the method an incision is made to expose one of the femoral arteries (eg: ipsilateral), which flows from the corresponding iliac artery, and using the

Seldinger needle technique, a 0.035" diameter floppy tipped flexible guidewire is inserted into and through the femoral artery and then the iliac artery 12 into the aorta 11 such that it traverses the aneurysm. An 8 French haemostatic sheath is then introduced to control bleeding. An angiographic catheter is introduced to allow an angiogram to be taken of the palient to show the position of the renal arteries 14, 15 and other relevant anatomical structures in the patient.

An Amplatz extra stiff (AES) guidewire 23 (0.035" diameter) is then passed through the angiographic catheter into the aorta 11 (see Fig. 7a). After withdrawal of the angiographic catheter, the stiff guidewire 23 is left in situ.

A catheter sheath 21, preferably of 24 French, and trocar are then introduced into the aorta 11 over the stiff guidewire 23 (see Fig. 7a). A balloon catheter 24 is then introduced into the sheath 21.

As is depicted in more detail in Fig. 6 the balloon catheter 24 is a delivery catheter which is pre-packaged with a bifurcated graft 10, having the first and second tubular graft extensions 19a. 19b separated at a bifurcation point 40, and a thin catheter 25 containing a guidewire 26 extending in a first direction up through the first tubular extension 19a and then in a second different direction into the second tubular extension 19b. The catheter 24 and thin catheter 25 can be linked together below the graft 10 in a common catheter sheath 56 which serves to better ensure correct positioning of the catheter 25 and guidewire 26 on placement of the graft 10 in the vessel. In addition to being slidable through the tubular graft extensions 19a.19b, the catheter 25 can be fixed in place in the graft 10 prior to insertion of the graft 10 into a vessel. The catheter 26 can be sutured, glued or woven into the body of the graft 10.

While the guidewire 26 is depicted in Fig. 6 inside a catheter 25, it can be readily envisaged that only the guidewire 26 could be disposed in the first and second tubular graft extensions 19a. 19b. In an alternative arrangement depicted in Fig. 6a. the guidewire 26 is positioned within a tubular channel 22 formed in the body of the graft 10. The channel 22 serves to ensure that the guidewire 26 remains in the desired position in the first and second tubular graft extensions 19a, 19b following packaging of the graft 10 about the balloon 20 and before placement of the balloon catheter 24 in the aorta 11. When the balloon catheter 24 is positioned within the aorta 11 at the desired position, the sheath 21 is partially withdrawn to free the graft 10 and the balloon 20 inflated (see Fig. 7b). The inflation of the balloon 20 of catheter 24 expands the upstream end of the first graft 10 and causes it to engage its upstream end against the aorta wall above the aneurysm but downstream of the renal arteries 14 and 15. The first graft 10 is of such a length that the short tubular extensions 19a, 19b are disposed wholly within the aorta 11. The balloon 20 is then deflated but the balloon catheter 24 is left in place for the time being (see Fig. 7c). Deflation of the balloon 20 will allow blood lo flow down the graft 10 distending each of the tubular extensions 19a. 19b.

The thin catheter 25 is preferably 3 French and the guidewire 26 of a non-kinking material so that the guidewire 26 may be extended relative to the catheter 25 in a downstream direction (see Fig. 7c). In the method depicted in Fig. 7. the catheter 25 and guidewire 26 respectively have at their tip a small inflatable balloon 50,55. The details of the balloons 50,55 are depicted in more detail in Figs. 6, 6b and 6c. The balloons 50,55 are inflated to help the catheter 25 and guidewire 26 to be carried and directed by blood flow into the contralateral iliac artery 13.

An enlarged view of the balloons 50,55 adjacent respectively the free ends of the catheter 25 and guidewire 26 are depicted in Figs. 6b and 6c. The catheter 25 has two lumens 52 and 53. The guidewire 26 passes through the first lumen 52. The end of the second lumen 53 is sealed and a small hole 51 has been formed in the outer surface of the catheter 25. A latex balloon 50 is annularly bonded to the outer surface of the catheter 25 at 50a. When the balloon 50 is to be inflated, liquid or gas is injected down the second lumen

53 such that it passes through the hole 51 and inflates the balloon 50.

Similarly, the guidewire 26 has a lumen 54 down which air can be injected to inflate the balloon 55 disposed at the free end of the guidewire 26.

While inflatable balloons are preferred, other expandable devices can be envisaged. For example, in an alternative embodiment, the balloons 50,55 on the catheter 25 and guidewire 26 could be replaced by an expandable umbrella. An example of a type of umbrella that could be utilised is depicted in Fig. 6d. Disposed at the free end of the guidewire 26 is an umbrella 70. The umbrella 70. which is depicted in the expanded configuration in Fig. 6d, is expanded by a wire 71 extending through a lumen 73 in the guidewire 26. The wire 71 is attached to stays 72 so that on retraction of wire 71 the stays

72 articulate to expand the umbrella 70. While the umbrella 70 is on the guidewire 26 it can be readily envisaged that a similar arrangement could be utilised on the catheter 25. In a further alternative, the balloon 55 on the guidewire 26 can be replaced by a small solid bead 80 of material such as epoxy resin or titanium as depicted in Fig. 6e. The bead 80 preferably has a larger profile than the guidewire 26.

In certain applications it is desirable once the catheter 25 is in a desired position in a vessel to further expand the balloon 50 at the free end of the catheter 25 until the balloon 50 engages the wall of the vessel and holds the catheter 25 in a desired position within the vessel to provide additional anchorage during passage of the guidewire 26 through the vessel.

Once the guidewire 26 is correctly placed in the contralateral femoral artery, a cut down is effected to that femoral artery which is cross-clamped and an arteriotomy effected. If the guidewire 26 has been guided fully into the contralateral femoral artery, the guidewire 26 is simply recovered by drawing the guidewire through the incision or puncture made in the artery. If the guidewire 26 has not been guided fully into the contralateral femoral artery, a snare or similar device can be introduced through the contralateral femoral artery to grab the guidewire and draw it back to the incision or puncture site for retrieval. Once the guidewire 26 is retrieved, the balloon 50 at the end of the catheter 25 is then deflated and the catheter 25 is then withdrawn via the ipsilateral side. Another catheter 27 is then fed through the contralateral femoral artery up the guidewire 26 until it is within the first graft 10 and reaches at least to the top of the second tubular extension 19b (see Fig. 7d). The thin guidewire 26 is then withdrawn and a thicker guidewire 30 inserted through the contralateral femoral artery into the

catheter 27. The catheter 27 is then removed and a catheter sheath 21a, preferably of 24 French, and trocar are introduced over the stiff guidewire 30 (see Fig. 7e).

Prior to extending the guidewire 26 into the contralateral iliac and femoral arteries, a catheter sheath (that can be similar to catheter sheath 21) can be extended upstream through the contralateral femoral and iliac arteries to reduce any tortuosity that may be present in these arteries and so facilitate guiding of the guidewire 26 therethrough.

A second balloon catheter 24a, such as is depicted in Fig. 9. on which is packaged a second tubular graft 10a, is then introduced through catheter sheath 21a until its upper end is well within the second tubular extension 19b at its upper end and within the iliac artery 13 at its lower end. The balloon 20a on the catheter 24a is inflated such that the upper end of graft 10a is frictionally engaged with the second tubular extension 19b (see Fig. 7f). The inflation of the balloon 20a on the catheter 24a supports the graft

10a during the withdrawal of the first balloon catheter 24 through the ipsilateral artery 12. The balloon 20a on the catheter 24a is then deflated and the catheter 24a maintained in place to provide continued support for the graft 10. 10a in the aorta 11 while the third graft 10b is positioned. The catheter sheath 21a is then removed (see Figs. 7f and 7g) and a third balloon catheter on which is packaged a tubular graft 10b (the third balloon catheter and graft 10b can be identical to that depicted in Fig. 9) is introduced into the sheath 21 on guidewire 23. It is advanced until its upstream end is within the first tubular extension 19a and, following partial withdrawal of the sheath 21, is then deployed. The third graft 10b positioned on the third balloon catheter is thus urged at its upstream end into contact with first tubular extension 19a and at its downstream end into contact with the right iliac artery 12 (see Fig. 7h).

The stiff guidewires 23 and 30 are now withdrawn and the contralateral incision sutured. A second angiographic examination now takes place and if the grafts 10, 10a and 10b are correctly placed and functioning the haemostatic sheath 21 is withdrawn and the right femoral incision sutured. The result is a functioning trouser graft bridging an aneurysm such as is depicted in Fig. 7i. The operation may be carried out using a general anaesthetic, an epidural anaesthetic or. in suitable cases, using only a local anaesthetic.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.