FIELD OF THE INVENTION
The present invention generally relates to a bifurcated graft and an apparatus and method for delivering the same within the body of a patient using a minimally invasive procedure. More particularly, the present invention includes a bifurcated vascular graft having two hollow cylindrical limb grafts of an equal first diameter attached to one another along a portion of their circumferences at their first ends and a third hollow cylindrical body graft of a larger diameter circumferentially positioned over the first two hollow cylindrical limb grafts such that the remaining unconnected end circumferences of the first two hollow cylindrical limb grafts are connected about an end circumference of the third hollow cylindrical body graft thereby bisecting the diameter of the third hollow cylindrical body graft in half.
The present invention also includes an apparatus and method for delivering the bifurcated vascular graft of the present invention which includes first and second hollow limb tubes of approximately equal diameter and varying lengths for containing the two hollow cylindrical limb grafts, a third hollow body tube having a larger diameter than the first and second hollow limb tubes for containing the hollow cylindrical body graft, a metal tube for containing a guide wire, and a hollow delivery tube which is capable of encompassing the first and second hollow limb tubes, the hollow body tube, and the metal tube.
BACKGROUND OF THE INVENTION
Endoluminal repair or exclusion of aortic aneurysms has been performed for the past several years. The goal of endoluminal aortic aneurysm exclusion has been to correct this life threatening disease in a minimally invasive manner in order to effectuate a patient's quick and complete recovery. Various vascular grafts exist in the prior art which have been used to exclude aortic aneurysms. These prior art grafts have been met with varying degrees of success.
Initially, straight tube grafts were used in the abdominal aorta to exclude the aneurysmal sac from the blood stream thereby resulting in the weakened aortic wall being protected by the graft material. These straight tube grafts were at first unsupported meaning that they employed stents at their proximal and distal ends to anchor the proximal and distal ends of the graft to the healthy portions of the aorta thereby leaving a midsection of the graft or prosthesis that did not have any internal or stented support. Although this type of graft at first appeared to correct the aortic aneurysm, it met with many failures. The unsupported nature of its midsection allowed the graft to migrate distally as well as exhibit significant proximal leakage due to the enlargement of the aorta without adaptation of the graft, such as enlargement of the graft, to accommodate the change in diameter of the aorta.
Later, technical improvements in stent design led to “self-expanding” stents. In addition, latter improvements produced “Nitinol” stents which had a “memory” that was capable of expanding to a pre-determined size. Coincidentally, graft designers began to develop bifurcated grafts having limbs which extended into the iliac arteries. The development of bifurcated grafts allowed for the treatment of more complex aneurysms.
With the advent of bifurcated grafts, the need for at least a one centimeter neck from the distal aspect of the aneurysmal sac to the iliac bifurcation in order to treat the aneurysm with an endoluminal graft was no longer needed. However, proximal necks of at least 0.5 to 1 centimeter distance from the renal arteries to the most proximal aspect of the aneurysm are still required.
Many bifurcated grafts are of a two piece design. These two piece designs require the insertion of a contralateral limb through a separate access site. These types of grafts are complex to deploy and have the potential for leakage at the connection site of the two limbs of the graft. One piece bifurcated grafts have also been designed. However, there deployment is still somewhat complicated and has torsion tendencies.
One piece bifurcated gafts are well known in the art. For example, U.S. Pat. No. 2,845,959 discloses a one piece seamless woven textile bifurcated tube for use as an artificial artery. Yarns of varying materials can be used to weave the bifurcated graft including nylon and plastic yarns. U.S. Pat. Nos. 3,096,560 and 3,029,819 issued to Liebig and Starks, respectively, disclose woven one piece bifurcated grafts which are constructed by performing specific types of winding and weaving about a smooth bifurcated mandrel.
U.S. Pat. No. 4,497,074 describes a one piece bifurcated graft which is made from a preformed support in the shape of the bifurcated graft (i.e. mould). In a first stage, a gel enabling a surface state close to that of the liquid-air interface to be obtained at the gel-air interface is deposited by dipping or coating the preform with a sol which is allowed to cool. A hardenable flexible material such as a silicone elastomer by dipping or spraying the material on the mould in a second stage. Finally, after hardening of the material, the prosthesis is removed from the mould. In U.S. Pat. No. 4,816,028 issued to Kapadia et al., there is shown a one piece woven bifurcated vascular graft having a plurality of warp threads running in the axial direction and a plurality of weft threads running in the transverse direction. Further, U.S. Pat. No. 5,108,424 issued to Hoffinan, Jr. et al. discloses a one piece bifurcated collagen-impregnated dacron graft. The bifurcated graft includes a porous synthetic vascular graft substrate formed by knitting or weaving with at least three applications of dispersed collagen fibrils.
The Herweck et al. patent, U.S. Pat. No. 5,197,976, discloses a continuous one piece bifurcated graft having plural longitudinally parallel tube structures which are attached to one another over at least a portion of their longitudinal exteriors. The tube structures can be manually separated to form a branched tubular structure. The prosthesis is manufactures by paste forming and stretching and/or expanding highly crystalline unsintered polytetrafluoroethylene (PTFE). Paste forming includes mixing the PTFE resin with a lubricant, such as mineral spirits, and then forming the resin by extrusion into shaped articles.
Although all of the above described one piece bifurcated grafts have eliminated the problems of leakage and graft failure at the suture or juncture site associated with two piece bifurcated grafts which join together two separate grafts to form the bifurcated graft, problems still exist with these one piece bifurcated grafts. For example, the previously described one piece bifurcated grafts do not include an integral support structure to prevent the deformation, twisting or collapse of the graft limbs. Further, the same problems with graft migration that existed with straight tube grafts still exist with the one piece bifurcated grafts. Accordingly, there is a need for a stable and durable bifurcated vascular graft which is structured to prevent the migration of the graft and the deformation and obstruction of the blood flow through the limbs of the bifurcated graft.
Endoluminal implantation is a common technique for implanting vascular grafts. Typically, this procedure involves percutaneously inserting a vascular graft or prosthesis by using a delivery catheter. This process eliminates the need for major surgical intervention thereby decreasing the risks associated with vascular and arterial surgery. Various catheter delivery systems for prosthetic devices are described in the prior art.
For example, bifurcated vascular grafts have been created by combining grafts with stents on delivery systems in order to secure the graft ends to the blood vessel thereby stabilizing the bifurcated graft. In U.S. Pat. No. 5,360,443 issued to Barone et al. A method for repairing an abdominal aortic aneurysm is described. The method comprises the steps of 1) connecting an expandable and deformable tubular member, such as a stent, to each of the tubular passageways of a bifurcated graft, 2) disposing the bifurcated graft and deformable tubular members within the aortic and iliac arteries, and 3) expanding and deforming each deformable tubular member with a catheter to secure each tubular passageway of the bifurcated graft within the appropriate artery. This reference only discloses a catheter delivery method for deploying the aortic portion of the bifurcated graft. The same catheter is supposedly used to also expand and secure the associated stents within the iliac arteries. The Palmaz et al. patent, U.S. Pat. No. 5,316,023, describes a method and apparatus for repairing an abdominal aortic aneurysm in an aorta having two iliac arteries. This method includes the steps of connecting a first tubular graft to a first deformable and expandable tubular member, connecting a second tubular graft to a second deformable and expandable tubular member, disposing the first tubular graft and first tubular member upon a first catheter having an inflatable portion, disposing the second tubular graft and second tubular member upon a second catheter having an inflatable portion, intraliminal delivering the first and second tubular grafts, tubular members and catheters to the aorta and disposing at least a portion of each tubular graft within the abdominal aortic aneurysm, and expanding the tubular members with the inflatable catheters to secure them and at least a portion of their associated tubular grafts within the aorta. This patent reference employs two separate unconnected straight grafts which are employed within an aorta to form a bifurcated graft.
Further, U.S. Pat. No. 4,617,932 issued to Komberg discloses a device for inserting a graft into an artery comprising a plurality of nested tubes each having an upper and lower end. A first outer tube has a means for guiding and positioning an arm means at its upper end. The arm means is movably attached to the upper end of another tube located inside of the first tube and extending above the first outer tube. The lower ends of the tubes are adaptable for fastening means and the inside tube extends below the end of the first outer tube. Delivery and placement of a bifurcated graft is illustrated. U.S. Pat. No. 5,522,883 issued to Slater et al. describes an endoprosthesis stent/graft deployment system which includes a tubular delivery catheter, a radially expandable prosthesis positioned over the catheter, a removable endoprosthesis support assembly located adjacent the catheter opening and having an arm extending through the catheter which keeps the endoprosthesis in a compressed state, and a release mechanism insertable through the catheter for removing the support assembly.
U.S. Pat. No. 5,104,399 issued to Lazarus also describes an artificial graft and delivery method. The delivery system includes a capsule for transporting the graft through the blood vessel, a tube connected to the vessel which extends exterior to the vessel for manipulation by a user, and a balloon catheter positioned within the tube. Finally, U.S. Pat. No. 5,489,295 issued to Piplani et al. discloses a bifurcated graft and a method and apparatus for deploying the bifurcated graft. The Piplani et al. graft includes a main tubular body, first and second tubular legs joined to the main tubular body in a bifurcation, a first expandable attachment means for anchoring the main body located adjacent the opening for the first body, and a second expandable attachment means located adjacent the opening of the first tubular leg for anchoring the first tubular leg. The graft is intraluminally implanted using a catheter that is inserted into the aortic bifurcation through a first iliac artery so that the first attachment means adjacent the opening of the main body can be anchored in the aorta and the second attachment means adjacent the opening of the first tubular leg can be anchored in the first iliac artery. The second tubular leg is deployed into the second iliac artery by using a pull line attached to the second tubular leg. The Piplani et al. patent also discloses a deployment device consisting of a capsule catheter, a balloon catheter, and a separate expandable spring attachment means.
The previously described deployment methods, systems and devices do not allow for a bifurcated graft which is fully supported with self expandable stents to be delivered and implanted within an arterial bifurcation. A use of any of the previously described deployment devices or systems to implant the structural supported bifurcated graft of the present invention would result in failure due to the inability of those devices and systems to deliver and anchor the second supported limb within the second iliac artery. The previously described methods and systems simply do not allow for the delivery and implantation of a bifurcated vascular graft whose three open ends are supported by stents. Accordingly, not only is there a need for a structurally supported stable and durable bifurcated graft which is not susceptible to migration and leaking, but there is also a need for a delivery apparatus and method for deploying and implanting such a bifurcated graft.
SUMMARY OF THE INVENTION
It is a principal object of the present invention to provide a bifurcated vascular graft and a method and apparatus for deploying the bifurcated vascular graft.
It is another object of the present invention to provide a bifurcated vascular graft having partial structurally supported limbs which will not deform, twist, or collapse thereby preventing the obstruction of blood flow through the limbs of the bifurcated vascular graft.
It is yet another object of the present invention to provide a bifurcated vascular graft having a structurally supported main graft body which lends support to an unsupported portion of the limbs of the bifurcated vascular graft in order to prevent migration of the bifurcated vascular graft.
It is still another object of the present invention to provide a structurally supported, physically stable bifurcated vascular graft which will occlude small blood vessels from bleeding into the bifurcated vascular graft area.
It is still another object of the present invention to provide a bifurcated vascular graft having separate limb channels thereby allowing for partial deployment of the bifurcated graft. The advantage of this design can be seen when one limb of the graft fails to deploy due to anatomic or structural problems. In that event, the successfully deployed graft limb will be capable of routing blood to the occluded limb by way of a femoral-femoral bypass. Most of the present bifurcated graft designs are not recoverable in this way and their failure to deploy usually forces a conversion to classic surgery.
It is yet another object of the present invention to provide a method and apparatus for deploying any one-piece bifurcated graft, including the bifurcated vascular graft of the present invention, within the body of a patient.
Still another object of the present invention is to provide a method and apparatus for intraluminally deploying a one-piece.bifurcated graft, including the bifurcated vascular graft of the present invention, within a patient's body which is simple and efficient.
Yet another object of the present invention is to provide a method and apparatus for repairing an abdominal aortic aneurysm which is noninvasive and which does not require suturing of the graft to the aortic wall or iliac arteries.
In brief, the bifurcated vascular graft of the present invention includes:
a hollow tubular body member having first and second open ends;
a first hollow tubular limb member having first and second open ends; and
a second hollow tubular limb member having first and second open ends wherein the first open end of each of the first and second hollow tubular limb members is connected to the hollow tubular body member near the first open end of the hollow tubular body member such that a length of the limb members are circumferentially contained within the hollow tubular body member.
The bifurcated vascular graft may include stents or similar support structures that are placed adjacent to the three openings contained in the bifurcated vascular graft. One stent may be positioned such that it encompasses the entire interior surface of the hollow tubular body member while two additional stents may be positioned about the exterior surface near the second ends of the first and second hollow tubular limb members, respectively. Cuffs may also be formed at the ends of these limb members by folding the second ends of the grafts back over the stents.
A method for making the bifurcated vascular graft of the present invention includes the steps of:
a) cutting about a middle circumference of a thin hollow tube until approximately ¾ of the circumference is cut;
b) folding the thin hollow tube at the cut away from the uncut portion to form two hollow tubular limb members having equal diameters which are attached to one another along the fold;
c) positioning the hollow tubular limb members within a hollow tubular body member having a diameter at least twice the diameter of the hollow tubular limb members; and
d) attaching the cut ends of the hollow tubular limb members to an end of the hollow tubular body member such that a length of the limb members are circumferentially contained within the hollow tubular body member.
The method may also include the steps of positioning a first structural support adjacent the end of the hollow tubular member containing the attachment of the cut ends of the two hollow tubular members wherein the first structural support is located about an interior of the hollow tubular member, and positioning second and third structural supports about an exterior of the two hollow tubular limb members, respectively, at ends of the two hollow tubular limb members that are opposite the fold.
In another aspect of the present invention, the preferred apparatus for deploying a bifurcated vascular graft within the body of a patient includes:
a first limb tube for loading the first limb;
a second limb tube for loading the second limb wherein the first and second loaded limb tubes are positioned parallel to one another;
a graft body tube for loading the main graft body wherein the graft body tube is positioned adjacent to parallel ends of the first and second limb tubes; and
an outermost tube for loading the first and second limb tubes and the graft body tube such that all of said tubes are contained within the outermost tube.
Another embodiment of the deployment apparatus includes first and second limb tube members which can both be inserted into the graft body tube at the same time. The deployment apparatus may also include a metal tube and guide wire which are insertable throughout an entire length of the apparatus The first and second limb tubes have approximately equal diameters and the second limb tube is preferably shorter than the first limb tube.
Finally, the method of the present invention for intraluminally delivering a bifurcated vascular graft having a main graft body which bifurcates into first and second limbs within a patient's body includes the steps of a) loading the first and second limbs and the main graft body into separate tubes, b) inserting the tubes endoluminally within the patient, c) positioning the tubes within the patient, and d) deploying the limbs and the main body graft one at a time by removing their respective tubes. One example in which this simple and noninvasive method may be used is in the repair of an abdominal aortic aneurysm.
Additional objects, features and advantages of the varying aspects of the present invention will become more apparent from the following description in which the preferred embodiments of the present invention are set out in detail in conjunction with the accompanying drawings.