DEVICE FOR TREATING ANEURYSMS

Abstract: A device (30) for treating aneurysms comprises a bag (31) removably attached to the distal end of a catheter (14), the bag being arranged to be inserted in an aneurysm (20) and being of flexible and stretchable material and being permeable to blood components. Once the bag is inserted, individual GD coils (18) are introduced therein. The bag is inserted by a shoulder (42) or a widened portion (50) of a guide wire (40) engaging a marker ring (46). The bag material may encourage clotting. In another embodiment the bag (131) is located around the end of the catheter (114) during insertion. When insertion is completed, electrolysable struts (32, 172) are removed to separate the bag from the catheter.

Description: DEVICE FOR TREATING ANEURYSMS The present invention relates to a device tor treating aneurysms and in paπicular to a device for use in the endovascular treatment of intracraπial aneurysms. Two earlier patent documents disclose similar devices but, because they concern devices for blocking vessels within the patient, are not designed for occluding aneurysms. In paπicular, U.S. 5,334.210 discloses a vascular occlusion assembly which comprises a bag made of rip stop nylon material so as to prevent the passage of blood. The bag has a predetermined diamond shape and thus would not be suitable for conforming to aneurysms. Moreover, the heavy and non-stretch nature of the material of the bag would make it difficult to steer through fine intracranial blood vessels. No guide wire is provided and the bag is attached and detached by a frictional arrangement. Similarly WO96/01591 also discloses a self-expanding vascular occlusion device. A pre- moulded basket of metal fabric is collapsed for passage through a catheter, placed in location by a guide wire affixed to the basket, and subsequently expanded within a channel in a patient's body. Since the passage of a metallic body is traumatic to patients, the basket moves along the interior of the catheter. Devices in accordance with the present invention are especially suitable for use with a Guglielmi Detachable Coil arrangement (GD coil) as disclosed in Guglielmi G.. Vinuela F.. Duckwiler G.. Dion J.. et al. Endovascular treatment of posterior circulation aneurysms using electrically detachable coils. J Neurosurgery. 77: 515-524, 1992. Saccular intracraπial (cerebral) aneurysms occur when regions of weakness in the wall of intracranial arteries result in the development of balloon-like swellings on the sides of the arteries. They are important because they are prone to burst and cause haemorrhage over the surface of the brain (subarachnoid haemorrhage). This can result in death in over 30% of patients within 24 hours and a further 25-30% will die within the next four weeks without some form of surgical intervention. Until recently the conventional treatment of cerebral aneurysms was to perform a neuro-surgical operation to place a clip across the neck of the aneurysm, analogous to tying the neck of a balloon. Over the past 10 to 15 years, endovascular techniques of aneurysm occlusion have evolved. The common principle of these techniques is that devices or materials are delivered by a tube (catheter) through the parent artery into the aneurysm where they induce clotting of the blood (thrombosis) in the aneurysm and effectively remove it from the circulation. The catheter is generally inserted via the femoral artery in the groin and the procedure monitored by x-ray fluoroscopy. The devices therefore have to be manipulable remotely, at a distance of approximately one metre without the help of direct vision. In the mid 1980s, balloons were used, made of latex or silicone rubber, to occlude the aneurysm. The results were poor and the mortality high. The reasons for this were: 1. It is rare that an aneurysm can be perfecdy filled with one balloon. 2. If more than one balloon is used, large unfilled spaces must remain in the aneurysm (one sphere cannot be perfectly filled with more than one smaller spheres). 3. Distension of the aneurysm wall by the balloon(s) is likely to occur and cannot be seen or measured. Other workers had greater success using sort coils of inert metal, generally platinum, to pack the aneurysm and induce thrombosis within it. The first coils were ' free' in that they were simply pushed up the catheter into the aneurysm and once out of the catheter they could not be retrieved. This made the procedure difficult to control and hence risky. In 1991 a major advance in coii technology, the GD coil, was developed and it remains the only accepted device used in the e .covascular treatment of cerebral aneurysms. Although essentially simply a soft platinum coil. :t differs from the ' free' coils in tha: it is captive and therefore controllable until the user chooses to release it. The GD coil has proved very successful especially for aneurysms of the posterior intracranial circulation. It is often used in the treatment of aneurysms which are thought to be inoperable by other means. The GD coil is not wimout problems, however, and amongst these are: 1. Relatively poor results in large ( > lcm diameter) or giant ( > 2.5cm diameter) aneurysms, generally because of a tendency for the coil mass to pack down and for the neck region of the aneurysm to enlarge with time after treatment. 2. Failure of endothelium to grow across the neck of treated aneurysms. 3. Tendency for coils to proiapse out of wide necked aneurysms and obstruct the parent artery. 4. Early (procedural) or delayed (post treatment) rupture of the coils through the aneurysm wall. The present invention seeks to overcome, or reduce, one or more of the above problems. According to a first aspect of the present invention there is provided a device for treating aneurysms comprising a catheter and. removably attached to one end of the cameter, a bag arranged to be inserted in an aneurysm and of a material which is permeable to at least some of the components of the blood. The connection of the catheter to the bag is such that, with the bag inside the aneurysm, one or more GD coils, or other suitable inserts, can be placed inside the bag before it is disconnected from the catheter. The bag may be provided with a guide wire to assist insertion of the bag and the catheter. The bag may also comprise one or more marker rings, and the guide wire may have a shoulder which engages one of the rings in the manner of a one-way drive. The material of the bag is preferably flexible and stretchable in the manner of nylon stockings so that it can conform to the interior size and shape of the aneurysm. The material is non- metallic and may be made from natural or synthetic fibre material. The material of the bag may be such as to encourage clotting or. alternatively, to discourage clotting. The bag may be provided as part of a kit of parts including a bag. a catheter to which the bag is removably attached, and a guide wire. According to a second aspect of the present invention there is provided a device for treating aneurysms comprising a catheter and, removably attached to one end of the catheter, a bag arranged to be inseπed in an aneurysm and of a material which is flexible and locally stretchable. According to a third aspect of the present invention there is provided a device for introducing an annular or pan-annular member into a patient, comprising a catheter having an element at or adjacent one end thereof with at least one electrode extending along the cameter to said element, said element being connected to said member by two or more spaced struts, die struts being arranged to be removed eiectrolyticaJly when an electric current is passed through said electrode. The element on the catheter is preferably also annular or pan-annular so that the struts provide a stable arrangement for maintaining the member and the element reiatively fixed, e.g. with their planes substantially parallel. According to a fourth aspect of die present invention there is provided an arrangement for introducing a bag into a patient, wherein the bag includes a substantially annular opening and a guide wire is provided with a first ponion which passes freely through the opening and a second poπion which does not, whereby die guide wire constitutes a one-way drive means for introduction of the bag. The first ponion may be a narrow end poπion on the end of a shaft which constitutes the second poπion, the poπions defining a step or shoulder therebetween. Alternatively, the second poπion may be constituted by a widened section of shoπ extent, e.g. a ball-shaped member on a guide wire of otherwise uniform thinner cross-section. The opening in the bag may be provided by a marker ring. Prefeπed embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure I is a sectional view of a conventional GD coil inside an intra-cranial aneurysm; Figure 2 is a view of the aneurysm of Figure I after it has been packed with GD coils; Figure 3 is a view of a device in accordance with a first embodiment of the present invention inside an intra-cranial aneurysm; Figure 4 is an enlarged view of the device of Figure 3; Figure 5 is a similarly enlarged view of the device of Figures 3 and 4, but in a collapsed state for inseπion; Figure 6 shows a modified device in accordance with die present invention: and Figure 7 shows a device in accordance with a second embodiment of the present invention. When using the GD coils alone, according to the prior an and shown in Figures 1 and 2, each device 10 comprises a coil IS welded or soldered by means of a single connection on to a pushing steel wire 1 1 which is very thin just proximal to a solder joint 12. The wire is electrically insulated up to a point approximately 1mm from the joint 12. The device 10 is introduced into the aneurysm 20 via a catheter 14. Normal cranial arteries are indicated at 21. Platinum markers 16 on the catheter 14 and the pushing wire 1 1, when aligned, indicate that the coil 18 is in an ideal position for detachment. Once the device 10 has been manipulated into an ideal position, a small positive voltage (approximately 3.5V) is applied to the proximal end of the wire. The negative terminal is attached to an earthing needle in the patient's groin. A current of 1mA passes which causes electrolytic erosion of the distal end of the pushing wire and detachment of die coil 18 in approximately 2 minutes. Fuπher coils 18 are inseπed in sequence until the aneurysm is well packed and it becomes difficult to inseπ any more, see Fig. 2. Figures 3 to 5 show a device 30 in accordance with the present invention comprising a bag or envelope 31 forming a liner and removably attached by means of two steel detachment struts 32 to the distal end of a catheter 14. The basis concept of this embodiment is to inseπ the bag 31 into the aneurysm 20 before inseπiπg the GD coils. Briefly, the bag 31 is an approximately spherical envelope of material which is porous to liquids, including blood. It is provided in a range of sizes which can be matched to die aneurysm 20. It is inseπed into the aneurysm 20 on die end of the catheter 14 and remains attached to the catheter while GD coils 18 (or o ier materials) are inseπed into it. thus expanding it against the walls of the aneurysm. When the coil mass is complete and detached, die bag 31 is detached from its delivery cadieter 14 and die cadieter wididrawn. A guide wire 40, Fig. 5, normally employed to inseπ just a catheter, is here used to direct the bag 31 at die end of catheter i 4 to die site of the aneurysm 20. The guide wire has a tip 41 of naπow cross-section forming a shoulder 42 with the remainder of the wire. Tip 41 may have a lengdi of approximately 1 to 2 cm and is more flexible than die remainder of the wire to assist inseπion. The wire cross-sections are such that wire 40 can pass freely through a platinum base (or south-polar) marker ring 36 of bag 31 , but only tip 41 can pass through a platinum apical (or north-polar) marker ring 46. Thus by virtue of shoulder 42 engaging the apical marker 46, the guide wire operates as a one-way drive for inseπing the bag 31 and the attached cadieter 14. Inseπion is facilitated by the wider pan of wire 40 keeping the bag stretched longitudinally and thus stretching the bag into a relatively long narrow configuration. This facilitates navigation in the blood vessels and guidance into die aneurysm. Alignment of bag base marker 36 and cameter marker 16 is useu to ensure correct location of die bag 31. When die bag is correctly positioned, the guide wire 40 is withdrawn ieaving the bag attached to the cadieter 1 - GD coils 18 attached to respective pusher wires 1 1 are then introduced sequentially along cadieter 14 and inseπed in the bag 31 as in ie previously-known method. The bag dien expands to conform to the interior of die aneurysm as shown in Fig. 3. When die bag 31 is packed to a satisfactory amount and the last GD coil 18 has been detached and its pusher wire 1 1 removed, the bag 31 is then detached from the catheter 14. The catheter detachment mechanism is a modification of die GD coil attachment, and electrolytic detachment is possible. The bag has attached to its base a small ring (not shown) of platinum or other suitable material, and of die same or similar diameter as die cadieter. This ring is mounted on top of the distal marker ring 16 of die delivery catheter and is attached to it by the two thin steel struts 32. The distal marker ring 16 is in turn connected to a fine electrode 49 embedded in the wall of the delivery catheter Detachment is by electrolysis of the steel struts 32 in much die same way as a GD coil is detached. The mateπal of die bag 3 . :s a very fine knitted, braided or woven fabric allowing some degree of local stretch. The bag is as non-bulk> as possible m its collapsed state, to pass through the guide catheter and blood vessels, but has to be able to expand :o the size of the aneurysm. possibly up to 3cm diameter, idiout significant resistance untii it reaches its design size. A range of sizes w ill be made for different aneur sms. Its knit, braid or weave is dense enough to resist penetration by the tip or a coil 18. A preferred material is 5-denιer nylon. The bag is strong enough to contain d e coils 18 and prevent them prolapsing out of me neck of die aneurysm 20. Thus die entire oag 31 is arranged to be located wi in die aneurysm, leaving the blood vessels 21 completely clear. Tne use of the bag 31 strengthens the aneurysm walls to reduce the risk of aneurysm rupture, bridges its neck and contains the coils, facilitating insertion of the coils 18 and reducing the chance of coil prolapse. Also, the bag 31 is of stretchy material and is not self-expanding; aldiough it is of approximately spherical shape, it conforms to die shape of die paπicular aneurysm. panicularlv upon die inseπion of coils 18. Fuπher. die bag induces fibrosis in die aneurysm walls, strengthening diem permanently and also forms a framework for endothelial cells to grow across the neck of die aneurysm. thus restoring normal blood flow in die parent aπery. It allows better treatment of giant aneurysms and reduces die likelihood of regrowdi of the aneurysm. Various modifications may be made to the above -described device. For example, as shown in the modification of Fig. 6, die guide wire 40 can have a shoπ region 50 of increased width, e.g. of the type known as a "ball". This is provided between the tip 41 and the shaft of the guide wire. In this case the microcati eter 14 has a helical electrode 59 embedded in its wall for electrolysing d e struts 32. Alternatively, die way in which die device 30 is inserted may be changed and die marker rings 36, 46 may be of the same diameter or the end of cadieter 14 may be arranged to pass through the base marker 36 but not the apex marker 46. The references to rings include rings of any shape and also to paπ-πngs. Any number of struts 32 may be provided including one. or diree or more. Alternatively, mechanical attachment and detachment devices might be employed or a frictional attachment followed by detachment by pulling die catheter 14 out or pushing off die bag 31. The material of the bag 31 may be a very fine version of the types of material used to make tights. Natural fibres such as silk, or man-made fibres such as nylon. Lycra. Dacron or Teflon may be appropriate. Porous membranes such as Gore-Tex may be considered. (Gore-Tex is conventionally thought of as impermeable to water-based liquids: however if it is pre-wetted widi alcohol and the alcohol is then replaced with water, water will pass freely dirough it. Plasma will also pass through it though the cellular elements of blood will not). Although the chosen material may act as a framework for the invasion by fibroblasts or endothelial cells, it is possible to impregnate die fabric with other materials, e.g. collagen, to stimulate ceil growth or heparin to reduce its thrombogenicity. In a modification, the bag may be in the form of a bailoon. e g. of Dacron sheet material. having a plurality of perforations. This has the advantages of being strong, smoodi and lightweight and compact. However, it may not be sufficiently elastic to conform to the shape of a particular aneurysm Electrodes 49, 59 can be of braided conductive material embedded in die catheter wall. In die embodiment of Fig 7 a device 130 has a microcatheter 1 14 which together with its marker ring 1 16 can actually pass through die south-polar ring 136 of die liner bag 131. The ring 136 is free to move to and fro along the distal end region of the catheter 114. A detachable ring 1 17, which is too wide to pass dirough south-polar ring 136. is attached to catheter marker ring by two electrolysable struts 172. Ball 150 of the guide wire 140 is too broad to pass dirough the north-polar ring 146. but sufficiently narrow to pass dirough the detachable ring 1 17. die terminal marker 1 16 and the cadieter 1 14 Again guide wire 140 has a relatively flexible tip 141 Also, catheter 1 14 has an electrode (not shown) embedded in its walls for removing struts 172 when desired. In use. die device 130 is assemoled with ring 1 17 inside bag 131. so that the bag 131 is loosely retained on the distal end or tr-e cadieter The device is steered into die aneurysm widi die bag 131. die catheter 1 14 and the guide w re 140 in approximately tr.e relative positions shown. aldiough die catheter could ce advanced .lightly relative to the bag The detachable ring 117 can be pushed right up against die noπh-Dolar ring 146 or die bag. The guide wire 140 is then wmdrawn rrom die catheter, and die cameter is retracted slightly so that its distal end lies near the centre or the bag. Coils 18 can tren be deployed through the catheter and into the bag insice the aneurysm. As the bag 131 is filled, the catheter can be urged towards the south-polar ring 136. but ring 1 1 7 prevents the catheter from leaving die bag. When the bag has been filled, the struts 1 " 2 are electrolysed away so that ring 1 17 is detached. Catheter 1 14 is dien withdrawn from bag 131 and removed from tr.e patient. The south-polar ring 136 ensures diat ring 1 T is retained inside the bag widi the coiis 18: accordingly, ring 1 17 should be made of an appropriate material. An advantage of this embodiment is that it is more easily steerable towards and into the aneurysm. Also, it permits a more accurate control of the position of the release of the coils 18 within the bag 131. The bags 31, 131 may be filled with elements other than GD coils, e.g. elements of different shapes and/or elements which contain or include a material which can initiate a healing response. The inserts could include detachable or pushable platinum coiis, injectable panicles or materials which are injected as a liquid but which solidify in d e bag. These materials may or may not include a bio-active material to induce a healing response. Indeed, if the bags 31, 131 are made of a suitable material widi a suitable porosity, there may be no need to fill them with elements 18 and it may be enough to cause die bags to inflate within the aneurysm. Also, die bags may be impermeable to all components of blood. The above-described devices can also be used with aneurysms located elsewhere in die body. In conclusion, a summary of some of die propeπies that the prefeπed bags exhibit is as follows: 1. Small enough, in the collapsed state, to pass through existing guide catheter systems. 2. Flexible enough to negotiate tortuous blood vessels. 3. Steerable by a guide wire. 4. Expandable to its design size by GD coils. 5. Strong enough to contain the coils and strengthen the aneurysm. 6. Non-toxic. 7. Have radio-opaque markers so that its position can be monitored. 8. Securely attached to delivery catheter but detachable when necessary. 9. Allow invasion by and act as a framework for fibroblasts and endothelial ceils. 10. Stretchable between longitudinal and approximately spherical configurations.

Claims: CLAIMS 1. A device (30, 130) for treating aneurysms comprising a catheter (14, 1 14) and, removably attached to one end of the cadieter, a bag (31, 131) arranged to be inserted in an aneurysm and of a material which is permeable to at least some of the components of the blood. 2. A device according to claim 1, wherein die bag (30, 131) is of a flexible and stretchable material. 3. A device according to claim 1 or 2, wherein me cadieter is in communication with the interior of the bag such that, with the bag inside an aneurysm, one or more inserts can be placed inside die bag before it is disconnected from die cadieter. 4. A device according to any preceding claim, wherein the bag has one or more marker devices (36. 46; 136, 146). 5. A device according to claim 4, wherein die or each marker device is in the form of a ring. 6. A device according to claim 5, wherein the bag has a guide wire (40, 140) widi a widened section (42, 50) which engages one of the marker rings in the manner of a one-way drive. 7. A device according to any preceding claim, wherein the material of the bag (31, 131) is such as to encourage a healing response. 8. A device according to any preceding claim, wherein the material of the bag (31, 131) comprises nylon or another synthetic fibre. 9. A device according to any of claims 1 to 7, wherein the material of the bag (31, 131) comprises a natural fibre. 10. A device according to any of claims 1 to 7, wherein the bag (31. 131) is of a knitted material. 11. A device according to any of claims 1 to 7, wherein die bag (31. 131) is of a woven material. 12. A device according to any of claims 1 to 7, wherein the bag (31, 131) is of a braided material. 13. A device (30, 130) for treating aneurysms comprising a catheter (14, 114) and, removably attached to one end of the catheter, a bag (31, 131) arranged to be inserted in an aneurysm and of a material which is flexible and locally stretchable. 14. A device according to any preceding ciaim, wherein die bag comprises an annular or pan-annular member (36) and the catheter has an element (16) at or adjacent one end diereof with at least one electrode (49) extending along die catheter to said element, said element being connected to said member by two or more spaced struts (32), the struts being capable of being removed electrolytically when an electric current is passed through said electrode. 15. A device according to any one of claims 1 to 13, wherein the catheter comprises, at or adjacent its distal end. an annular or pan-annular member ( 117) of relatively large width and an element (1 16) of relatively naπow width and having at least one electrode (59) extending along the catheter to said element, said element being connected to said member by two or more spaced struts (172), die struts being capable of being removed electrolytically when an electric current is passed through said electrode. 16. A device according to claim 15. wherein die bag ( 131) includes a proximal ring or pan- ring ( 136) which is of a size to permit passage of said element ( 116) but not to allow passage of said member (1 17). 17. A device according to claim 14, 15 or 16, wherein said element (16, 116) on the catheter is also annular or pan-annular, die struts (32, 172) being arranged to maintain the planes of said member (36. 1 17) and said element substantially parallel. 18. A device (30, 130) for introducing an annular or pan-annular member (36, 117) into a patient, comprising a catheter (14, 1 14) having an element (16. 116) at or adjacent one end thereof, with at least one electrode (49, 59) extending along die cadieter to said element, said element being connected to said member by two or more spaced struts (32, 172), the struts being arranged to be removed electrolytically when an electric cuπent is passed through said electrode. 19. An arrangement for introducing a bag (30, 130) into a patient, wherein the bag includes a substantially annular opening (46, 146) and a guide wire (40, 140) is provided with a first poπion (41, 141) which passes freely through the opening and a second poπion which does not, whereby the guide wire constitutes a one-way drive means for introduction of the bag. 20. A kit of pans comprising a catheter (14, 114), a bag (31, 131) which is removably attached to d e catheter, the material of the bag being permeable to at least some components of the blood, and one or more inserts (18) for inseπion into the bag. 21. A kit of pans according to claim 20, wherein the inserts (18) are GD coils. 22. A kit of pans according to ciaim 20 or 21, and further comprising a guide wire (40, 140).

Inventors: JEFFREE MARTIN ANDREW, JEFFREE, MARTIN, ANDREW
Applicants: JEFFREE MARTIN ANDREW, JEFFREE, MARTIN, ANDREW
Application year: 1998
Main classification: A61B17
IPC codes: A61B17