Apparatus and methods for endoluminal graft placement

Information

  • Patent Grant
  • 8206427
  • Patent Number
    8,206,427
  • Date Filed
    Monday, June 5, 1995
    29 years ago
  • Date Issued
    Tuesday, June 26, 2012
    12 years ago
Abstract
A vascular graft comprises a perforate tubular compressible frame having a fabric liner disposed over at least a portion of the frames lumen. The graft may be used in combination with a base structure to form a bifurcated graft in situ. The base structure compresses a compressible frame having a fabric liner which defines a pair of divergent legs. The base structure is positioned within the aorta so that one leg enters each iliac. The tubular grafts can then be introduced into each leg to form the bifurcated structure. A graft delivery catheter includes a controllably flared sheath which facilitates recapture of a partially deployed graft.
Description
BACKGROUND OF THE INVENTION

1. Field of the Invention


The present invention relates generally to apparatus and methods for endoluminal placement of grafts, stents, and other structures. More particularly, the present invention relates to a low profile, compressible graft structure and apparatus and methods for vascular placement of such structures for the treatment of abdominal and other aneurysms.


Vascular aneurysms are the result of abnormal dilation of a blood vessel, usually resulting from disease and/or genetic predisposition which can weaken the arterial wall and allow it to expand. While aneurysms can occur in any blood vessel, most occur in the aorta and peripheral arteries, with the majority of aortic aneurysms occurring in the abdominal aorta, usually beginning below the renal arteries and often extending distally into one or both of the iliac arteries.


Aortic aneurysms are most commonly treated in open surgical procedures where the diseased vessel segment is bypassed and repaired with an artificial vascular graft. While considered to be an effective surgical technique, particularly considering the alternative of a usually fatal ruptured abdominal aortic aneurysm, conventional vascular graft surgery suffers from a number of disadvantages. The surgical procedure is complex and require experienced surgeons and well equipped surgical facilities. Even with the best surgeons and equipment, however, patients being treated frequently are elderly and weakened from cardiovascular and other diseases, reducing the number of eligible patients. Even for eligible patients prior to rupture, conventional aneurysm repair has a relatively high mortality rate, usually from 3% to 10%. Morbidity related to the conventional surgery includes myocardial infarction, renal failure, impotence, paralysis, and other conditions. Additionally, even with successful surgery, recovery takes several weeks, and often requires a lengthy hospital stay.


In order to overcome some or all of these drawbacks, endovascular graft placement for the treatment of aneurysms has been proposed. Although very promising, many of the proposed methods and apparatus suffer from other problems. Often times the proposed graft structures will have exposed anchors or frame which can be thrombogenic. It is also difficult to provide graft structures which remain sealed to the blood vessel lumen to prevent the leakage or bypass of blood into the weakened aneurysm, especially when subjected to external deforming forces which result from vessel expansion and contraction as the heart beats. Many vascular graft structures have difficulty in conforming to the internal arterial wall, particularly since the wall can have a highly non-uniform surface as a result of atherosclerosis and calcification and is expanding and contracting with the patient's heartbeat and blood flow. Additionally, many previous vascular graft structures are difficult to position and anchor within the target region of the vessel.


For these reasons, it would be desirable to provide improved apparatus and methods for the endovascular placement of intraluminal grafts for treating aneurysms and other conditions. It would be particularly desirable if the graft structures were easy to place in the target region, displayed little or no thrombogenicity, provided a firm seal to the vascular wall to prevent leakage and blood bypass, and were able to conform to uniform and non-uniform blood vessel walls, even while the wall is expanding and contracting with the patient's heartbeat.


2. Description in the Background Art


Vascular grafts and devices for their transluminal placement are described in U.S. Pat. Nos. 5,219,355; 5,211,658, 5,104,399; 5,078,726; 4,820,298; 4,787,899; 4,617,932; 4,562,596; 4,577,631; and 4,140,126; and European Patent Publications 508 473; 466 518; and 461 791.


Expandable and self-expanding vascular stents are described in U.S. Pat. Nos. 5,147,370; 4,994,071; and 4,776,337; European patent Publications 575 719; 556 850; 540 290; 536 610; and 481 365; and German patent Publication DE 42 19 949. A flexible vascular stent structure having counter wound helical elements, some of which are separated at particular locations to enhance flexibility, is commercially available from Angiomed, Karlsruhe, Germany, as described in a brochure entitled Memotherm Iliaca Stents.


Catheters for placing vascular stents are described in U.S. Pat. Nos. 5,192,297; 5,092,877; 5,089,005; 5,037,427; 4,969,890; and 4,886,062.


Vascular grafts intended for open surgical implantation are described in U.S. Pat. Nos. 5,236,447; 5,084,065; 4,842,575; 3,945,052; and 3,657,744; and PCT applications WO 88/00313 and WO 80/02641; and SU 1697787.


Nickel titanium alloys and their use in medical devices are described in U.S. Pat. Nos. 4,665,906 and 4,505,767.


SUMMARY OF THE INVENTION

The present invention comprises apparatus and methods for the endoluminal placement of intraluminal grafts for the treatment of disease conditions, particularly aneurysms. The intraluminal grafts comprise a radially compressible, perforate tubular frame having a proximal end, a distal end, and an axial lumen between said ends. An interior liner, typically a fabric, polymeric sheet, membrane, or the like, covers all or most of the surface of the lumen of the tubular frame, extending from a near-proximal location to a near-distal location. The liner is attached to the frame at at least one end, as well as at a plurality of locations between said ends. Optionally, a second liner may be provided over at least a portion of the exterior of the frame to cover both sides of the frame. Such exterior coverage provides a circumferential seal against the inner wall of the blood vessel lumen in order to inhibit leakage of blood flow between the graft and the luminal wall into the aneurysm or stenosis which is being treated.


The grafts of the present invention will find particular use in the treatment of vascular conditions, such as abdominal and other aneurysms, vascular stenoses, and other conditions which require creation of an artificial vessel lumen. For the treatment of vascular stenoses, the graft may serve as a stent to maintain vessel patency in a manner similar to that described in the above-described U.S. and foreign patent documents relating to stents. Other intraluminal uses of the devices and methods of the present invention include stenting of the ureter, urethra, biliary tract, and the like. The devices and methods may also be used for the creation of temporary or long term lumens, such as the formation of a fistula.


Such graft structures provide a number of advantages over previously proposed designs, particularly for vascular uses. By covering the lumen of the tubular frame, thrombogenicity of the graft resulting from exposed frame elements is greatly reduced or eliminated. Such reduction of thrombogenicity is achieved while maintaining the benefits of having a frame structure extending over the graft. Such an external frame helps anchor the graft in place and maintain patency and evenness of the graft lumen, both of which are advantages over graft structures which are anchored and supported only at each end. The vascular grafts of the present invention are also self-expanding and easy to place. The self-expanding nature of the frame also counteracts external deforming forces that may result from the continuous physiologic expansion and contraction of the blood vessel lumen. Moreover, the lack of cleats, tines, or other penetrating elements on the graft allows the graft to more closely conform to the surrounding vessel wall and facilitates retrieval and/or repositioning of the graft, as will be described in more detail hereinafter. Additionally, the resilient tubular frame structure permits the graft to conform to even irregular regions of the blood vessel wall as the wall is expanding and contracting as a result of the pumping of the patient's heart.


The tubular frame preferably comprises a plurality of radially compressible band or ring structures, each of which have a relaxed (i.e., non-compressed) diameter which is greater than the diameter of the blood vessel to be treated. Adjacent compressible band members may be independent of each other or may be joined at one or more locations therebetween. If joined, the bands are preferably joined at only two diametrically opposed points to enhance flexibility of the frame over its length. Independent band members will be held together by their attachment to the interior and/or exterior liner(s).


Alternatively, the tubular frame may comprise a plurality of laterally compressible axial members, with adjacent axial members preferably not being directly connected to each other. The axial members will usually comprise a multiplicity of repeating structural units, e.g., diamond-shaped elements, which are axially connected. The axial members will be attached to the inner liner, either by stitching or by capturing the axial members in pockets formed between the inner liner and an outer liner disposed over the frame. The pockets may be formed by attaching the inner and outer liners to each other along axial lines between adjacent axial members.


The present invention also provides methods and systems for the in situ placement of bifurcated grafts for the treatment of aorto-iliac segments and other bifurcated lumens. The system comprises a bifurcated base structure including a proximal anchor, typically a self-expanding frame, which defines a common flow lumen and a pair of connector legs that establish divergent flow lumens from the common flow lumen. The system also includes a first tubular graft which can be anchored within first of the connector legs to form a continuous extension of the first divergent flow lumen and a second tubular graft which can be anchored within a second of the connector legs to form a continuous extension of the second divergent flow lumen. The method of placement comprises first introducing the bifurcated base structure so that the anchor section is positioned within a primary vessel, i.e., the aorta, below the renal arteries. After the bifurcated base structure is anchored, the first tubular graft is introduced into the first connector leg and anchored between said leg and the first branch artery, e.g., the right iliac. The second tubular graft is then inserted into the second connector section and anchored between the second connector and the second branch artery. By properly selecting the dimensions of the bifurcated base structure, the first tubular graft, and the second tubular graft, the resulting bifurcated graft structure can have dimensions which are specifically matched to the vessel dimensions being treated. Preferably, the bifurcated base structure, first tubular graft, and second tubular graft, will be formed from radially compressible perforate tubular frames having interior and/or exterior liners, generally as described above for the preferred vascular graft of the present invention. The radially compressible perforate tubular frame on the base structure, however, will terminate above the region where the connector legs diverge. The connector legs below the divergent region will be reinforced by placement and expansion of the tubular graft structures therein.


The present invention further provides a delivery catheter for endovascular placement of radially compressible grafts or stents, such as the vascular grafts and bifurcated base structures described above. The catheter comprises an elongate shaft having a proximal end and a distal end. Preferably, a retaining structure is provided near the distal end of the shaft for holding the graft or the stent on the shaft until such a time that the graft or stent is positively released, e.g., by withdrawing a pull wire which extends through locking stays on either side of the graft or stent. The delivery catheter further comprises a sheath slidably mounted over the shaft. The sheath is initially disposed to cover and restrain the radially compressed graft or stent while the catheter is being intervascularly introduced to a desired target location. The sheath may then be withdrawn, releasing the radially compressed graft or stent to occupy and anchor within the vasculature or other body lumen.


Preferably, the graft or stent will remain fixed to the shaft even while the sheath is being withdrawn so that the physician can recapture the graft by advancing the sheath back over its exterior. Only after the graft or stent is fully expanded at the target location within the vessel lumen is the graft or stent finally released. Preferably, the sheath will have a flared or outwardly tapered distal end to facilitate both release and recapture of the graft or stent by axial translation of the sheath. The flared end may be fixed or deployable, i.e., selectively shiftable between a flared and a non-flared configuration. Preferably, the flared end will be deployable so that the sheath may be introduced with the distal end in its non-flared configuration to minimize its profile. After properly positioning the sheath, the distal end may be opened to assume its tapered configuration.





BRIEF DESCRIPTION OF THE DRAWINGS


FIG. 1 is a side view of a vascular graft constructed in accordance with the principles of the present invention.



FIG. 1A is a side view of a first alternate embodiment of a vascular graft constructed in accordance with the principles of the present invention.



FIG. 1B is a side view of a second alternate embodiment of a vascular graft constructed in accordance with the principles of the present invention.



FIG. 2 is a side view of a radially compressible perforate tubular frame of a type which may be used in a vascular graft of FIG. 1.



FIGS. 3A and 3B are a schematic illustrations showing the joining pattern of the radially compressible band members of the tubular frame of FIG. 2.



FIG. 4 illustrates a structure which has been etched from a tube and which may be subsequently expanded to form the tubular frame of FIG. 2.



FIG. 5 illustrates a bifurcated base structure which is part of a system for forming a bifurcated graft in situ.



FIG. 6 illustrates, the distal end of a graft and stent placement catheter constructed in accordance with the principles of the present invention.



FIGS. 7-12 illustrate placement of a bifurcated aortic graft using the bifurcated graft placement system of the present invention.





DESCRIPTION OF THE SPECIFIC EMBODIMENT

The present invention provides apparatus and methods for the transluminal placement of graft structures, particularly within the vascular system for treatment of aneurysms and other vascular conditions, but also in other body lumens, such as ureter, urethra, biliary tract, gastrointestinal tract, and the like, for the treatment of other conditions which benefit from the introduction of a reinforcing or protective structure in the lumen. The apparatus and methods can also find use in the creation of artificial lumens through solid tissue and structures, such as the placement of a TE fistula via an endoscope. The vascular grafts will be placed endovascularly. As used herein, “endovascularly” will mean placement by percutaneous or cutdown transluminal procedures using a catheter over a guidewire under fluoroscopic guidance. The catheters and guidewires may be introduced through conventional access sites to the vascular system, such as through the brachial and subclavian arteries for access to the aorta and through the femoral arteries for access to the aorta or to peripheral and branch blood vessels.


A vascular graft according to the present invention will comprise a radially compressible perforate tubular frame and an inner or interior liner attached within a central lumen defined by the frame and optionally a second or outer liner formed over the exterior of the frame. The radially compressible frame can take a variety of forms, usually comprising or consisting of a plurality of independent or interconnected structural elements, such as rings, bands, helical elements, serpentine elements, axial struts, parallel bars, and the like, that can be compressed from a relaxed, large diameter configuration to a small diameter configuration to facilitate introduction, as discussed below. It is necessary, of course, that the liner(s) remain attached to the frame both in its radially compressed configuration and in its expanded, relaxed configuration.


A preferred configuration for the tubular frame comprises a plurality of radially compressible band members, where adjacent band members are joined to each other at only two diametrically opposed points in order to enhance flexibility. In a particularly preferred aspect, the diametrically opposed attachment points are rotationally staggered in order to provide flexibility in more than one direction. A preferred method for forming such a tubular frame is described in more detail hereinafter. In another preferred configuration, at least some of the bands of the frame are independent i.e., are not directly connected to each other. Instead, the bands are connected only to the liner(s) which maintain the axial integrity of the graft. Preferably, the independent bands are stitched or sealed between interior and exterior liners, as will be described in more detail below. Other suitable frame structures are described in the patent literature.


In an alternate configuration, the perforate tubular frame comprises a plurality of laterally compressible axial members which are attached directly, e.g., by stitching, or indirectly, e.g., by lamination, to the inner liner. The axial members may be a multiplicity of repeating structural elements, such as diamonds, or could be formed from two or more overlapping elements. By positioning the axial members in pockets formed between an inner liner and an outer liner, the axial elements will be able to flex independently while providing the desired radial compressibility and self-expansion characteristics for the graft.


The dimensions of the tubular graft will depend on the intended use. Typically, the graft will have a length in the range from about 50 mm to 500 mm, preferably from about 80 mm to 200 mm for vascular applications. The relaxed diameter will usually be in the range from about 4 mm to 45 mm, preferably being in the range from about 5 mm to 25 mm for vascular applications. The graft will be radially compressible to a diameter in the range from 3 mm to 9 mm, preferably from 4 mm to 6 mm for vascular applications.


The liner(s) will be composed of conventional biological graft materials, such as polyesters, polytetrafluoroethylenes (PTFE's), polyurethanes, and the like, usually being in the form of woven fabrics, non-woven fabrics, polymeric sheets, membranes, and the like. A presently preferred fabric liner material is a plain woven polyester, such as type 56 Dacron® yarn (Dupont, Wilmington, Del.), having a weight of 40 denier, woven at 27 filaments with 178 warp yarns per circumferential inch, and 78 yarns per inch in the fill direction.


The liner will be attached to the interior lumen of the tubular frame and will cover most or all of the interior surface of the lumen. For example, the liner may be stitched or otherwise secured to the tubular frame along a plurality of circumferentially spaced-apart axial lines. Such attachment permits the liner to fold along a plurality of axial fold lines when the frame is radially compressed. The liner will further be able to open and conform to the luminal wall of the tubular frame as the frame expands. Alternatively, when inner and outer liners are used, the liners may be stitched, heat welded, or ultrasonically welded together to sandwich the tubular frame therebetween. In an exemplary embodiment where a plurality of independent band members are disposed between interior and exterior liners, the liners are secured together along circumferential lines between adjacent band members to form pockets for holding the band members. In a second exemplary embodiment where a plurality of independent axial members are disposed between interior and exterior liners, the liners are secured together along axial lines to form pockets for holding the axial members.


The liner will preferably be circumferentially sealed against the tubular frame at least one end, preferably at both ends in the case of straight (non-bifurcated) grafts. It is also preferred in some cases that the distal and proximal end of the perforate tubular frame be exposed, i.e., not covered by the liner material, typically over a length in the range from about 1 mm to 25 mm. Frame which is not covered by the liner permits blood perfusion through the perforations and into branch arteries such as the renal arteries in the case of abdominal aorta grafts, while providing additional area for anchoring the frame against the blood vessel lumen. In an exemplary embodiment, the liner will extend through the frame and over the exterior surface near either or both ends to provide a more effective seal against the adjacent blood vessel wall.


The radially compressible perforate tubular frame will be composed of a resilient material, usually metal, often times a heat and/or shape memory alloy, such as nickel titanium alloys which are commercially available under the trade name Nitinol®. The frames may also be composed of other highly elastic metals, such as MP-35 N, Elgiloy, 316 L stainless steel, and the like. In the case of Nitinol® and other memory alloys, the phase transition between austenitic and martensitic states may occur between an introduction temperature, e.g., room temperature (approximately 22° C.), and body temperature (37° C.), to minimize stress on the unexpanded frame and enhance radial expansion of the frame from its radially compressed condition. Expansion can also be achieved based on the highly elastic nature of the alloy, rather than true shape recovery based on phase change.


In some cases, it may be desirable to form a tubular frame having different elastic or other mechanical properties at different regions along its length. For example, it is possible to heat treat different regions of the tubular frame so that some regions possess elastic properties while others become malleable so that they may be deformed by external force. For example, by providing at least one malleable end portion and an elastic (radially compressible) middle portion, the graft can be firmly expanded and implanted by internal balloon expansion force (to anchor the end(s) in the inner wall of the blood vessel) while the middle will remain open due to the elastic nature of the tubular member. Malleable end portions are a particular advantage since they can be expanded with a sufficient force, and re-expanded if necessary, to assure a good seal with the blood vessel wall. Alternatively, the malleable ends could be formed from a different material than that of the middle portion of the tubular frame. The use of different materials would be particularly convenient when the frame is formed from a plurality of independent bands, where one or more band members at either or both ends could be formed of a malleable metal. Usually, such malleable end(s) will extend over a distance in the range from 5 mm to 50 mm, preferably from 5 mm to 20 mm.


Malleable portions or segments can also be formed in other parts of the tubular frame. For example, some circumferentially spaced-apart segments of the tubular frame could be malleable while the remaining circumferential segments would be elastic. The frame would thus remain elastic but have an added malleability to permit expansion by applying an internal expansion force. Such a construction would be advantageous since it would allow the diameter of the graft or stent structure to be expanded if the initial diameter (which resulted entirely from elastic expansion) were not large enough for any reason. The proportion of elastic material to malleable material in the tubular frame can be selected to provide a desired balance between the extend of initial, elastic opening and the availability of additional, malleable opening. Such construction can be achieved by selective heat treatment of portions of a frame composed of a single alloy material, e.g. nickel titanium alloy, or by forming circumferential segments of the frame from different materials having different elastic/malleable properties. In particular, individual laterally compressible axial members 204 (as described in connection with FIG. 1B) could be formed from materials having different elastic/malleable properties.


Referring now to FIGS. 1-4, an exemplary graft structure 10 will be described. The graft structure 10 includes a fabric liner 12 and a radially compressible perforate tubular frame 14. For convenience, the frame 14 is illustrated by itself in FIG. 2. The frame is illustrated in its expanded (relaxed) configuration in each of these figures, but may be radially compressed by applying a radially inward compressive force, usually by placing the graft 10 in an outer sheath, as will be described in more detail hereinafter.


The tubular frame 14 comprises a plurality of radially compressible band members 11, each of which comprises a zig-zag or Z-shaped element which forms a continuous circular ring. Each band member 11 will typically have a width w in the range from 2 mm to 15 mm, and the tubular frame will comprise from 1 to 30 individual band members. Adjacent band members 11 are preferably spaced-apart from each other by a short distance d and are joined by bridge elements 13. Flexibility is enhanced by providing only two diametrically opposed bridge elements 13 between each adjacent pair of band members 11. As will be described further with reference to FIG. 1A, flexibility can be further enhanced by leaving the band members connected only by the liner.


Usually, the perforate tubular frame 14 will be left open at each end, e.g., at least a portion of the last band member 11 will remain uncovered by the liner 12. The liner 12 will be stitched or otherwise secured to the band members 11, preferably at the junctions or nodes when the element reverses direction to form the Z-pattern (although the stitching should not cross over between the band members in a way that would restrict flexibility). The liner 12 will usually pass outward from the inner lumen of the tubular frame 14 to the exterior of the frame through the gap between adjacent band members, as illustrated in FIG. 1. The portion of liner 12 on the exterior of the tubular frame 14 helps seal the end(s) of the graft 10 against the wall of the blood vessel or other body lumen in which it is disposed.


The joining pattern of adjacent band members 11 is best illustrated in FIGS. 3A and 3B. FIG. 3A illustrates the tubular frame 14 as it would look if unrolled onto a flat surface. FIG. 3B is similar to FIG. 3A, except that the band members are expanded. The expansion is shown at 30°, but will frequently extend up to 60° or higher in use.


A preferred method for forming the tubular frame 14 in the present invention may be described with reference to FIG. 4. A tube of the desired elastic material, such as nickel titanium alloy having a phase transformation temperature significantly below 37° C., preferably between 30° C. and 32° C., is obtained. The tube will have dimensions roughly equal to the desired dimensions of the frame when radially compressed. The tube may be drawn, rolled, or otherwise treated to achieve the desired wall thickness, diameter, and the like. Suitable wall thicknesses are in the range of about 0.1 mm to 0.5 mm. A pattern of axial slots is then formed in the tube, as illustrated in FIG. 4. The slots may be formed by electrical discharge machining (EDM), photochemical etching, laser cutting, machining or other conventional techniques. After the slots have been formed, the tube is mechanically expanded to its desired final (relaxed) diameter and heat treated at a suitable temperature to set the tube in the desired expanded state. Sharp edges are removed by conventional techniques, such as deburring, abrasive extrusion, or the like. The result of the expansion is the tubular frame illustrated in FIGS. 1 and 2.


Preferably, each end of the liner 12 will be circumferentially sealed at or near the distal and proximal ends of the tubular graft. As illustrated in FIG. 1A, this can be achieved by folding over the end of the liner 12 onto the external surface of the graft 10. Conveniently, this can be done through the gaps which are present between adjacent band members 14. Where the junctions 13 remain, the liner 12 can be carefully stitched onto the underlying surface of the frame, as shown at 18 in FIG. 1A. Other techniques for circumferentially sealing the liner include heat or ultrasonic welding of the liner, laminating an outer gasket, sewing an outer reinforcement member, or the like.


Referring now to FIG. 1A, an alternative embodiment 100 of a vascular graft constructed in accordance with the principles of the present invention will be described. The graft 100 comprises a perforate tubular frame 102 which includes a plurality of independent (non-connected) band members 104 separated from each other by gaps 106. The perforate tubular frame 102 is similar in construction to frame 14 of graft 10, except that adjacent band members 104 are not directly connected to each other. Band numbers 104 will be connected only by an inner liner 108 and an outer liner 110, where the inner and outer liners together encase or sandwich the otherwise free-floating band members 104. In order to secure the band members 104 in place, and secure the liners to the perforate tubular frame 102, the inner and outer liners are joined together along circumferential lines 112, preferably located in the gaps 106 between adjacent band members 104. The liners may be joined together by stitching, heat welding, ultrasonic welding, or the like. In the exemplary embodiment, the liners 108 and 110 are formed from polymeric sheet material and are joined together by ultrasonic welding. The band members 104 at each end of the graft 100 will have to be further secured to the liners 108 and 110. For example, they could be stitched, welded, or otherwise joined to the liners to hold them in place. The dimensions, materials, and other aspects of the graft 100 will be generally the same as those described previously for graft 10.


Referring now to FIG. 1B, a second alternative embodiment 200 of the vascular graft of the present invention is illustrated. The graft 200 comprises a perforate tubular frame 202 including a plurality of laterally compressible axial members 204. Each axial member 204 comprises a plurality of diamond-shaped structural elements which are connected to each other in a linear fashion. It will be appreciated that each diamond-shaped structural element is laterally compressible so that the frame 202 as a whole may be radially compressed from a reduced-diameter configuration to an expanded-diameter configuration. As illustrated in FIG. 1B, the frame is in a partially compressed configuration. The axial members 202 will be captured between an inner liner 206 and an outer liner 208. The inner liner 206 and outer liner 208 will be secured to each other along a plurality of axial lines 210 disposed between adjacent axial members 204. In this way, each axial member 204 will be captured within a pocket formed between the inner liner 206 and outer liner 208. As with previous embodiments, the ends of the frame may extend beyond the liners to provide for improved anchoring and perfusion on either side of the graft.


Referring now to FIG. 5, a bifurcated base structure for forming a bifurcated graft in combination with a pair of the vascular grafts 10 just discussed will be described. The bifurcated base structure 20 comprises an anchor segment 22, which typically will be a radially compressible perforate frame having a structure similar or identical to that just discussed. The frame of anchor 22 will typically have a length in the range from about 5 mm to 50 mm, and a diameter in the range from about 5 mm to 30 mm. A liner 24 will be disposed within the frame 22, typically being circumferentially sealed near the upper end of the frame, e.g., being folded over and stitched as described previously. As with the straight graft embodiment of FIGS. 1-4, the proximal end of the liner 24 will preferably be distally spaced-apart from the proximal end of the anchor segment 22, typically by a distance in the range from 1 mm to 25 mm. The fabric 24 defines a common flow lumen at its upper end and a pair of divergent flow lumens at its lower end, one in each leg 26 and 28. The legs 26 and 28 are preferably not covered by the frame of anchor 22. The fabric legs 26 and 28 will each have a diameter in the range from 6 mm to 18 mm and a length in the range from 5 mm to 30 mm. The dimensions of each leg need not be the same.


Referring to FIG. 6, a catheter 30 for delivering the vascular graft 10 or bifurcated base structure 20 will be described. The catheter 30 includes a shaft 32 having a pair of axially spaced-apart stays 34 and 36. A pull wire 38 extends through a lumen 40 of shaft 32 and through protrusions on each of the stays 34 and 36. A sheath 42 is slidably disposed over the shaft 32 so that it may be advanced over the stays 34 and 36. Guidewire GW extends through the shaft 32 within guidewire lumen 44 and shaft extension 46 to facilitate vascular introduction of the catheter 30. A radially compressible graft G (such as graft 10) is placed over the distal end of the shaft extension 46, generally being aligned between the stays 34 and 36. The pull wire 38 is then advanced through the stays 34 and 36 so that it passes through each end of the graft G to maintain the graft in place until the pull wire is withdrawn. While the pull wire 38 remains in place, the sheath 42 may be axially advanced over the graft to radially compress the graft into its desired low profile diameter. The sheath 42 includes a flared (i.e., outwardly tapered) distal end 56 to facilitate advancing the sheath over the graft, in particular so that the graft may be recaptured when it is partially deployed, as described hereinafter. The outward taper may be permanently fixed in the body of the sheath, but will preferably be selectively deployable between the tapered configuration and a non-tapered or straight configuration (shown in broken line) to facilitate introduction of the sheath through the vasculature or other body lumen. A variety of suitable mechanisms for selectively expanding the distal end of the sheath are known in the art, such as pull wires and the like. The sheath 42 will be introduced through the vasculature through a conventional introducer sleeve having a proximal hemostasis valve.


The catheter 30 may be modified to provide alternate delivery techniques for the graft G. For example, the catheter 30 may include a balloon at or near its distal end for use with grafts having malleable portions which need to be expanded. The catheter 30 might also include bumpers or other means for aligning the graft on the shaft 46 while the sheath 42 is being retracted. A variety of other catheter constructions and techniques for delivering the radially-compressible graft and stent structures of the present invention.


Referring now to FIGS. 7-12, placement of a bifurcated graft structure in an abdominal aortic aneurysm AA of a patient will be described. Initially, the delivery catheter 30 is introduced through an introducer sleeve 50 via an antegrade approach (e.g. the subclavian artery SC), as illustrated in FIG. 7. The bifurcated base structure is initially maintained within sheath 42 so that it remains radially compressed. After the compressed base structure 20 is properly positioned, the sheath 42 will be withdrawn, allowing the base structure 20 to expand in place, as illustrated in FIG. 8. The catheter 30 may then be withdrawn, leaving the guidewire GW in place. A vascular graft 10 is then mounted on the catheter 30 and reintroduced so that the compressed vascular graft lies within the fabric liner leg 28 while covered with sheath 42, as illustrated in FIG. 9. The sheath 42 is then withdrawn so that the vascular graft 10 will expand both within the leg 28 and the left iliac LI, as illustrated in FIG. 10. The catheter 30 is then withdrawn, and the guidewire is transferred from the left iliac LI to the right iliac RI. Alternatively, a separate guidewire could be introduced. Catheter 30 is then reintroduced over the guidewire with sheath 42 covering a second vascular graft 10 and advanced into the right iliac, as illustrated in FIG. 11. The sheath 42 is then withdrawn, allowing the second vascular graft 10 to expand within both the right iliac RI and the second leg 26 of the fabric liner. The completed bifurcated graft structure is then in place, as illustrated in FIG. 12, and the guidewire GW, catheter 30, and introducer sheath 50 may then be withdrawn.


Femoral access and retrograde placement of the graft structures of the present invention will be possible although such an approach is not presently preferred.


Positioning and repositioning of the stent-graft structure of the present invention can be facilitated by use of an ultrasonic imaging catheter or guidewire, such as the guidewires described in U.S. Pat. No. 5,095,911 and PCT WO 93/16642. Such ultrasonic guidewires can be used in place of the conventional guidewire GW illustrated in FIGS. 7-12, typically being sealed by a hemostasis valve at the proximal end of the delivery catheter 30. Locking means, clamps, markings, and the like, may be provided on either or both of the delivery catheter 30 and the imaging guidewire to assure proper positioning of the ultrasonic transducer within the stent-graft structure during the placement procedure. The aneurysm or other anomaly being treated can then be precisely located prior to release of the stent-graft 10. After partial placement, proper location of the stent-graft 10 can be confirmed with the ultrasonic imaging device. If the position is not correct, the stent-graft 10 can be drawn back into the sheath 42, and the stent-graft can be repositioned prior to complete release. The use of an ultrasonic imaging guidewire is advantageous since there is no need to exchange the guidewire for a separate ultrasonic imaging catheter.


Although the foregoing invention has been described in some detail by way of illustration and example, for purposes of clarity of understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims.

Claims
  • 1. A method for introducing a vascular graft into a primary artery which divides into first and second branch arteries, said method comprising: introducing and deploying a bifurcated structure including an anchor section and first and second connector sections so that the anchor section is disposed within the primary artery and the first and second connector sections extend toward the first and second branch arteries and thereafter;introducing a first tubular graft into the first connector section and anchoring said first tubular graft to extend between the first connector section and the first branch artery to form a first continuous flow path from the primary artery to the first branch artery; andintroducing a second tubular graft into the second connector section and anchoring said second tubular graft to extend between the second connector section and the second branch artery to form a second continuous flow path from the primary artery to the second branch artery.
  • 2. A method as in claim 1, wherein the primary artery is an aorta, the first branch artery is a right iliac, and the second branch artery is a left iliac.
  • 3. A method as in claim 1, wherein the anchor section of the bifurcated structure is radially compressed while being introduced.
  • 4. A method as in claim 3, wherein the anchor section is composed of a resilient material, said method further comprising releasing the radially compressed anchor section at a target location with the primary artery.
  • 5. A method as in claim 1, wherein the bifurcated structure is introduced through the primary artery in an antegrade direction.
  • 6. A method as in claim 1, wherein the bifurcated structure is introduced through a branch artery in a retrograde direction.
  • 7. A method as in claim 1, wherein the first tubular graft is radially compressed while being introduced.
  • 8. A method as in claim 7, wherein the first tubular graft is composed of a resilient material, said method further comprising releasing the radially compressed graft to anchor simultaneously within the first connector and the first branch artery.
  • 9. A method as in claim 1, wherein the first tubular graft is introduced through the primary artery in an antegrade direction.
  • 10. A method as in claim 1, wherein the first tubular graft is introduced through a branch artery in a retrograde direction.
  • 11. A method as in claim 1, wherein the second tubular graft is radially compressed while being introduced.
  • 12. A method as in claim 11, wherein the second tubular graft is composed of a resilient material, said method further comprising releasing the radially compressed graft to anchor simultaneously within the second connector and the second branch artery.
  • 13. A method as in claim 1, wherein the second tubular graft is introduced through the primary artery in an antegrade direction.
  • 14. A method as in claim 1, wherein the second tubular graft is introduced through a branch artery in a retrograde direction.
  • 15. A method for treating an aneurysm by introducing a vascular graft into a primary artery which branches into first and second branch arteries, said method comprising: introducing into a patient's vasculature an anchor section and first tubular graft of the vascular graft so that the anchor section is disposed within the primary artery and the first tubular graft is at least partially disposed within the first branch artery to form a first continuous flow path from the primary artery to the first branch artery; andsecuring a second tubular graft to the anchor section via a connector leg of the anchor section to form a second continuous flow path from the primary artery to the second branch artery, wherein each of the grafts comprises a tubular frame and a liner.
  • 16. A method as in claim 15, wherein the primary artery is an aorta, the first branch artery is a right iliac, and the second branch artery is a left iliac.
  • 17. A method as in claim 15, wherein the anchor section and first tubular graft of the vascular graft are radially compressed while being introduced.
  • 18. A method as in claim 17, wherein the anchor section and first tubular graft of the vascular graft are resilient, said introducing step comprising releasing the radially compressed anchor section and first tubular graft at a target location with the vasculature.
  • 19. A method as in claim 18, wherein the anchor section and first tubular graft of the vascular graft are introduced through the primary artery in an antegrade direction.
  • 20. A method as in claim 18, wherein the anchor section and first tubular graft of the vascular graft are introduced through a branch artery in a retrograde direction.
  • 21. A method as in claim 18, wherein the second tubular graft is radially compressed while being introduced.
  • 22. A method as in claim 21, wherein the second tubular graft is resilient, said method further comprising releasing the radially compressed second tubular graft to anchor within the connector leg on the anchor section.
  • 23. A method as in claim 22, wherein the second tubular graft is introduced through the primary artery in an antegrade direction.
  • 24. A method as in claim 22, wherein the second tubular graft is introduced through a branch artery in a retrograde direction.
  • 25. A method as in claim 15, wherein the introducing step comprises securing the first tubular graft to the anchor section of the vascular graft after the anchor section has been disposed within the primary artery.
  • 26. A method as in claim 25, wherein the first tubular graft is secured to the anchor section via a second connector leg of the anchor section.
  • 27. A method as in claim 26, wherein the first tubular graft is resilient and wherein the securing of the first tubular graft to the anchor section comprises releasing the first tubular graft from a compressed configuration to expand within the second connector leg and the first branch artery.
  • 28. A method as in claim 27, wherein the second tubular graft is resilient and wherein the securing of the second tubular graft to the anchor section comprises releasing the second tubular graft from a compressed configuration to expand within its respective connector leg and the second branch artery.
  • 29. A method as in claim 25, wherein the primary artery is an aorta, the first branch artery is a right iliac, and the second branch artery is a left iliac.
  • 30. A method as in claim 29, wherein the second tubular graft is resilient and wherein the securing of the second tubular graft to the anchor section comprises releasing the second tubular graft from a compressed configuration to expand within the connector leg and the left iliac.
  • 31. A method as in claim 25, wherein the anchor section of the vascular graft is radially compressed while being introduced.
  • 32. A method as in claim 31, wherein the anchor section is resilient, said introducing step comprising releasing the radially compressed anchor section at a target location with the vasculature.
  • 33. A method as in claim 32, wherein the anchor section of the vascular graft is introduced through the primary artery in an antegrade direction.
  • 34. A method as in claim 32, wherein the anchor section of the vascular graft is introduced through a branch artery in a retrograde direction.
  • 35. A method as in claim 25, wherein the first tubular graft is radially compressed while being introduced.
  • 36. A method as in claim 35, wherein the first tubular graft is resilient, said introducing step comprising releasing the radially compressed first tubular graft to anchor within a second connector leg on the anchor section.
  • 37. A method as in claim 36, wherein the first tubular graft is introduced through the primary artery in an antegrade direction.
  • 38. A method as in claim 36, wherein the first tubular graft is introduced through a branch artery in a retrograde direction.
  • 39. A method as in claim 36, wherein the second tubular graft is radially compressed while being introduced.
  • 40. A method as in claim 39, wherein the second tubular graft is resilient, said method further comprising releasing the radially compressed second tubular graft to anchor simultaneously within the connector leg on the anchor section and the second branch artery.
  • 41. A method as in claim 40, wherein the second tubular graft is introduced through the primary artery in an antegrade direction.
  • 42. A method as in claim 40, wherein the second tubular graft is introduced through a branch artery in a retrograde direction.
Parent Case Info

This is a Division of application Ser. No. 08/255,681 filed Jun. 8, 1994 now abandoned.

US Referenced Citations (253)
Number Name Date Kind
3657744 Ersek Apr 1972 A
3868956 Alfidi et al. Mar 1975 A
3878565 Sauvage Apr 1975 A
3890977 Wilson Jun 1975 A
3945052 Liebig Mar 1976 A
3996938 Clark, III Dec 1976 A
4140126 Choudhury Feb 1979 A
4149911 Clabburn Apr 1979 A
4214587 Sakura, Jr. Jul 1980 A
4225979 Rey et al. Oct 1980 A
4276874 Wolvek et al. Jul 1981 A
4306318 Mano et al. Dec 1981 A
4310354 Fountain et al. Jan 1982 A
4416028 Eriksson et al. Nov 1983 A
4425908 Simon Jan 1984 A
4503569 Dotter Mar 1985 A
4505767 Quin Mar 1985 A
4512338 Balko et al. Apr 1985 A
4545082 Hood Oct 1985 A
4553545 Maass et al. Nov 1985 A
4560374 Hammerslag Dec 1985 A
4562596 Kornberg Jan 1986 A
4577631 Kreamer Mar 1986 A
4577632 Grasset Mar 1986 A
4580568 Gianturco Apr 1986 A
4617932 Kornberg Oct 1986 A
4629458 Pinchuk Dec 1986 A
4649922 Wiktor Mar 1987 A
4655771 Wallsten Apr 1987 A
4665906 Jervis May 1987 A
4665918 Garza et al. May 1987 A
4681110 Wiktor Jul 1987 A
4719924 Crittenden et al. Jan 1988 A
4728328 Hughes et al. Mar 1988 A
4729766 Bergentz et al. Mar 1988 A
4731073 Robinson Mar 1988 A
4732152 Wallsten et al. Mar 1988 A
4733665 Palmaz Mar 1988 A
4739762 Palmaz Apr 1988 A
4757827 Buchbinder et al. Jul 1988 A
4762128 Rosenbluth Aug 1988 A
4768507 Fischell et al. Sep 1988 A
4772264 Cragg Sep 1988 A
4776337 Palmaz Oct 1988 A
4787899 Lazarus Nov 1988 A
4793348 Palmaz Dec 1988 A
4800882 Gianturco Jan 1989 A
4813434 Buchbinder et al. Mar 1989 A
4815478 Buchbinder et al. Mar 1989 A
4820298 Leveen et al. Apr 1989 A
4830003 Wolff et al. May 1989 A
4842575 Hoffman, Jr. et al. Jun 1989 A
4856516 Hillstead Aug 1989 A
4867173 Leoni Sep 1989 A
4872455 Pinchuk et al. Oct 1989 A
4872874 Taheri Oct 1989 A
4878906 Lindemann et al. Nov 1989 A
4886062 Wiktor Dec 1989 A
4886065 Collins, Jr. Dec 1989 A
4898577 Badger et al. Feb 1990 A
4913141 Hillstead Apr 1990 A
4913701 Tower Apr 1990 A
4922905 Strecker May 1990 A
4923464 DiPisa, Jr. May 1990 A
4938220 Mueller, Jr. Jul 1990 A
4950227 Savin et al. Aug 1990 A
4954126 Wallsten Sep 1990 A
4969458 Wiktor Nov 1990 A
4969890 Sugita et al. Nov 1990 A
4990151 Wallsten Feb 1991 A
4994071 MacGregor Feb 1991 A
5015253 MacGregor May 1991 A
5019085 Hillstead May 1991 A
5019090 Pinchuk May 1991 A
5035706 Giantureo et al. Jul 1991 A
5037392 Hillstead Aug 1991 A
5037427 Harada et al. Aug 1991 A
5041126 Gianturco Aug 1991 A
5042707 Taheri Aug 1991 A
5047050 Arpesani Sep 1991 A
5057092 Webster, Jr. Oct 1991 A
5061275 Wallsten et al. Oct 1991 A
5064435 Porter Nov 1991 A
5067957 Jervis Nov 1991 A
5078720 Burton et al. Jan 1992 A
5078726 Kreamer Jan 1992 A
5078736 Behl Jan 1992 A
5084065 Weldon et al. Jan 1992 A
5085635 Cragg Feb 1992 A
5089005 Harada Feb 1992 A
5092877 Pinchuk Mar 1992 A
5098440 Hillstead Mar 1992 A
5102417 Palmaz Apr 1992 A
5104399 Lazarus Apr 1992 A
5104404 Wolff Apr 1992 A
5108416 Ryan et al. Apr 1992 A
5116318 Hillstead May 1992 A
5122154 Rhodes Jun 1992 A
5123917 Lee Jun 1992 A
5133732 Wiktor Jul 1992 A
5135536 Hillstead Aug 1992 A
5147370 McNamara et al. Sep 1992 A
5151105 Kwan-Gett Sep 1992 A
5158548 Lau et al. Oct 1992 A
5161547 Tower Nov 1992 A
5163958 Pinchuk Nov 1992 A
5178630 Schmitt Jan 1993 A
5183085 Timmermans Feb 1993 A
5190058 Jones et al. Mar 1993 A
5190546 Jervis Mar 1993 A
5192297 Hull Mar 1993 A
5192307 Wall Mar 1993 A
5195984 Schatz Mar 1993 A
5201757 Heyn et al. Apr 1993 A
5201901 Harada et al. Apr 1993 A
5207695 Trout, III May 1993 A
5211658 Clouse May 1993 A
5219355 Parodi et al. Jun 1993 A
5235446 Majima Aug 1993 A
5236446 Dumon Aug 1993 A
5236447 Kubo et al. Aug 1993 A
5242399 Lau et al. Sep 1993 A
5246445 Yachia et al. Sep 1993 A
5246452 Sinnott Sep 1993 A
5266073 Wall Nov 1993 A
5269757 Fagan et al. Dec 1993 A
5272971 Fredericks Dec 1993 A
5275622 Lazarus et al. Jan 1994 A
5282823 Schwartz et al. Feb 1994 A
5282824 Gianturco Feb 1994 A
5282860 Matsuno et al. Feb 1994 A
5290305 Inoue Mar 1994 A
5292331 Boneau Mar 1994 A
5304200 Spaulding Apr 1994 A
5314472 Fontaine May 1994 A
5316023 Palmaz et al. May 1994 A
5330482 Gibbs et al. Jul 1994 A
5330500 Song Jul 1994 A
5330528 Lazim Jul 1994 A
5336164 Snider et al. Aug 1994 A
5342371 Welter et al. Aug 1994 A
5342387 Summers Aug 1994 A
5344425 Sawyer Sep 1994 A
5344426 Lau et al. Sep 1994 A
5354308 Simon et al. Oct 1994 A
5354309 Schnepp-Pesch et al. Oct 1994 A
5356423 Tihon et al. Oct 1994 A
5356433 Rowland et al. Oct 1994 A
5360443 Barone et al. Nov 1994 A
5365943 Jansen Nov 1994 A
5366504 Andersen et al. Nov 1994 A
5370618 Leonhardt Dec 1994 A
5370683 Fontaine Dec 1994 A
5375612 Cottencean et al. Dec 1994 A
5382261 Palmaz Jan 1995 A
5383892 Cardon et al. Jan 1995 A
5383926 Lock et al. Jan 1995 A
5383928 Scott et al. Jan 1995 A
5385152 Abele et al. Jan 1995 A
5387235 Chuter Feb 1995 A
5389106 Tower Feb 1995 A
5392778 Horzewski Feb 1995 A
5397345 Lazarus Mar 1995 A
5403341 Solar Apr 1995 A
5405377 Cragg Apr 1995 A
5409019 Wilk Apr 1995 A
5413597 Krajicek May 1995 A
5415664 Pinchuk May 1995 A
5429144 Wilk Jul 1995 A
5433200 Fleischhacker, Jr. Jul 1995 A
5433723 Lindenberg et al. Jul 1995 A
5443496 Schwartz et al. Aug 1995 A
5443497 Venbrux Aug 1995 A
5443498 Fontaine Aug 1995 A
5448993 Lynch et al. Sep 1995 A
5456713 Chuter Oct 1995 A
5464449 Ryan et al. Nov 1995 A
5464450 Buscemi et al. Nov 1995 A
5478349 Nicholas Dec 1995 A
5480382 Hammerslag et al. Jan 1996 A
5480423 Ravenscroft et al. Jan 1996 A
5484444 Braunschweiler et al. Jan 1996 A
5489295 Piplani et al. Feb 1996 A
5496344 Kanesaka et al. Mar 1996 A
5507767 Maeda et al. Apr 1996 A
5507768 Lau et al. Apr 1996 A
5507769 Marin et al. Apr 1996 A
5507771 Gianturco Apr 1996 A
5522880 Barone et al. Jun 1996 A
5522882 Gaterud et al. Jun 1996 A
5562678 Booker Oct 1996 A
5562724 Vorwerk et al. Oct 1996 A
5562726 Chuter Oct 1996 A
5562727 Turk et al. Oct 1996 A
5562728 Lazarus et al. Oct 1996 A
5571170 Palmaz et al. Nov 1996 A
5571173 Parodi Nov 1996 A
5575817 Martin Nov 1996 A
5578071 Parodi Nov 1996 A
5591195 Taheri et al. Jan 1997 A
5597378 Jervis Jan 1997 A
5607444 Lam Mar 1997 A
5609605 Marshall et al. Mar 1997 A
5609627 Goicoechea et al. Mar 1997 A
5613980 Chauhan Mar 1997 A
5617878 Taheri Apr 1997 A
5632763 Glastra May 1997 A
5632772 Alcime et al. May 1997 A
5634475 Wolvek Jun 1997 A
5639278 Dereume et al. Jun 1997 A
5653743 Martin Aug 1997 A
5662700 Lazarus Sep 1997 A
5669936 Lazarus Sep 1997 A
5676696 Marcade Oct 1997 A
5676697 McDonald Oct 1997 A
5683449 Marcade Nov 1997 A
5683450 Goicoechea et al. Nov 1997 A
5683451 Lenker et al. Nov 1997 A
5683453 Palmaz Nov 1997 A
5687723 Avitall Nov 1997 A
5693029 Leonhardt Dec 1997 A
5693083 Baker et al. Dec 1997 A
5693086 Goicoechea et al. Dec 1997 A
5709713 Evans et al. Jan 1998 A
5713913 Lary et al. Feb 1998 A
5713917 Leonhardt et al. Feb 1998 A
5716365 Goicoechea et al. Feb 1998 A
5718724 Goicoechea et al. Feb 1998 A
5733303 Israel et al. Mar 1998 A
5741325 Chaikof et al. Apr 1998 A
5752522 Murphy May 1998 A
5782904 White et al. Jul 1998 A
5788668 Leonhardt Aug 1998 A
5797949 Parodi Aug 1998 A
5824039 Piplani et al. Oct 1998 A
5824040 Cox et al. Oct 1998 A
5824041 Lenker et al. Oct 1998 A
5824042 Lombardi et al. Oct 1998 A
5824055 Spiridigliozzi et al. Oct 1998 A
5851210 Torossian Dec 1998 A
5860923 Lenker et al. Jan 1999 A
5871536 Lazarus Feb 1999 A
5938696 Goicoechea et al. Aug 1999 A
6024763 Lenker et al. Feb 2000 A
6045557 White et al. Apr 2000 A
6126685 Lenker et al. Oct 2000 A
6165213 Goicoechea et al. Dec 2000 A
6302906 Goicoechea et al. Oct 2001 B1
6379372 Dehdashtian et al. Apr 2002 B1
6554798 Mann et al. Apr 2003 B1
6565596 White et al. May 2003 B1
6582458 White et al. Jun 2003 B1
6613073 White et al. Sep 2003 B1
Foreign Referenced Citations (96)
Number Date Country
B-7960491 Aug 1993 AU
A-3295195 Jan 1996 AU
2079944 Apr 1993 CA
1 766 921 Jan 1970 DE
28 05 749 Feb 1977 DE
3918736 Dec 1990 DE
4219949 Dec 1993 DE
9319267.30 Feb 1994 DE
0145166 Jun 1985 EP
0145166 Jun 1985 EP
0 183 372 Apr 1986 EP
0274846 Jul 1988 EP
0 335 341 Apr 1989 EP
0364420 Apr 1990 EP
0364787 Apr 1990 EP
0 423 916 Apr 1991 EP
0 421 729 Oct 1991 EP
461791 Dec 1991 EP
0464755 Jan 1992 EP
0466518 Jan 1992 EP
466518 Jan 1992 EP
0 472 731 Mar 1992 EP
0479557 Apr 1992 EP
0480667 Apr 1992 EP
481365 Apr 1992 EP
0505686 Sep 1992 EP
508473 Oct 1992 EP
0518704 Dec 1992 EP
0518839 Dec 1992 EP
0518839 Dec 1992 EP
0533511 Mar 1993 EP
0 539 237 Apr 1993 EP
536610 Apr 1993 EP
540290 May 1993 EP
0540290 May 1993 EP
0540290 May 1993 EP
0 551 179 Jul 1993 EP
0556850 Aug 1993 EP
556850 Aug 1993 EP
0 565 251 Oct 1993 EP
0 566 245 Oct 1993 EP
0 541 443 Dec 1993 EP
575719 Dec 1993 EP
0 579 523 Jan 1994 EP
0 596 145 May 1994 EP
603959 Jun 1994 EP
0 621 016 Oct 1994 EP
0657147 Jun 1995 EP
0657147 Jun 1995 EP
0 656 198 Jul 1995 EP
0 684 022 Nov 1995 EP
0 686 379 Dec 1995 EP
0 783 874 Jul 1997 EP
0 792 627 Sep 1997 EP
2 678 508 Jan 1993 FR
2678508 Jan 1993 FR
2 714 816 Jul 1995 FR
2 189 150 Oct 1987 GB
05-76603 Mar 1993 JP
6-197985 Jul 1994 JP
1217402 Mar 1986 SU
1318235 Jun 1987 SU
1457921 Feb 1989 SU
1697787 Dec 1991 SU
WO 8002641 Dec 1980 WO
WO 8300997 Mar 1983 WO
WO 8800813 Feb 1988 WO
WO 8901320 Feb 1989 WO
WO8908433 Sep 1989 WO
WO 9004982 May 1990 WO
WO9107928 Jun 1991 WO
WO 9112047 Aug 1991 WO
WO9200043 Jan 1992 WO
WO 9206734 Apr 1992 WO
WO 9313825 Jul 1993 WO
WO 9315661 Aug 1993 WO
WO9317636 Sep 1993 WO
WO 9319804 Oct 1993 WO
WO9406372 Mar 1994 WO
WO 9412136 Jun 1994 WO
WO 9417754 Aug 1994 WO
WO 9424961 Nov 1994 WO
WO 9501761 Jan 1995 WO
WO 9505207 Feb 1995 WO
WO9508966 Apr 1995 WO
WO 9516406 Jun 1995 WO
WO 9521592 Aug 1995 WO
WO 9526695 Oct 1995 WO
WO9529725 Nov 1995 WO
WO 9610375 Apr 1996 WO
WO 9611648 Apr 1996 WO
WO9613228 May 1996 WO
WO9618361 Jun 1996 WO
WO 9628116 Sep 1996 WO
WO9703624 Feb 1997 WO
WO 9716219 May 1997 WO
Divisions (1)
Number Date Country
Parent 08255681 Jun 1994 US
Child 08463836 US