Abstract:
A resilient tubular graft is delivered into place within a body passage by elongating the graft to reduce its diameter and then directing the graft to the desired position while in the elongated condition. The graft is carried into position by a pair of elongate members mounted for longitudinal movement relative to one other. Flexible lines secure opposite ends of the graft to the respective elongate members whereby relative longitudinal movement of the members functions to elongate the graft and reduce its diameter. The lines extend around the graft to impart radial compression thereto simultaneously with elongation of the graft. Upon placement of the graft at the desired location within a body passage, the lines are released to permit the graft to expand into engagement with the passage. Barbs on the graft provide for secure engagement of the graft with a body passage.

Description:
This is a Continuation of application Ser. No. 08/714,627, filed Sep. 16, 1996, now abandoned, which is a continuation of application Ser. No. 08/462,218, filed Jun. 5, 1995, now abandoned, which is a divisional of application Ser. No. 08/089,290, filed Jul. 8, 1993, now U.S. Pat. No. 5,464,449, the disclosure of which is incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a prosthetic graft and a method and apparatus for placing the graft within a body passage. In its more particular aspects, the invention is concerned with a resilient tubular graft which may be reduced in diameter for delivery and then expanded into place. The invention is especially concerned with such a graft which may be deployed within the thoracic aorta, the abdominal aorta, or the femoral artery, via a groin incision. 
     The prior art teaches expansible tubular grafts for use in body passages. For example, U.S. Pat. No. 4,655,771 discloses such a graft which may be elongated for delivery and then expanded into place. With the device of that patent, the ends of the graft are held within tubular fixtures which are used to impart elongation to the graft to reduce its diameter during delivery. Once the graft is in place, these fixtures are removed to release the graft for expansion. The employment of the fixtures necessarily adds to the-bulk and complexity of the mechanism and limits its use. 
     Another example of an expansible intraluminal graft is found in U.S. Pat. No. 4,776,337. The device of that patent is fabricated of a malleable material which is delivered in a reduced diameter condition and, once in place, expanded by an angioplasty balloon to dilate and expand the lumen of a blood vessel. 
     The prior art also teaches expansible devices for vessel dilation embodying braided cylinders of an adjustable axial length structured such that a reduction in the length increases the radial size of the device. U.S. Pat. No. 4,572,186 shows such a device. 
     It is also known to provide sheaths which may be placed in vessels to facilitate the passage of other instruments or catheters therethrough. U.S. Pat. Nos. 4,493,711 and 4,798,193 teach such devices. 
     SUMMARY OF THE INVENTION 
     The graft of the present invention is resilient and of a tubular configuration adapted to assume a foreshortened enlarged diameter condition upon relaxation and, upon being elongated, assume a reduced diameter condition. The mechanism for delivery of the graft comprises an elongate placement means which extends longitudinally of the graft to carry the graft through a body passage and facilitate its placement. Flexible lines secure opposite ends of the graft to the elongate placement means. The lines are movable to selectively elongate the graft for delivery, or expand the graft for placement. A retractable sheath may be provided to shield the mechanism and graft during the delivery process. 
     The method of the invention comprises the steps of securing opposite ends of the graft to a placement member with flexible lines, moving the lines to elongate the graft, passing the placement member through a body passage with the graft carried thereby in a reduced diameter elongated condition, and positioning the graft and releasing the lines at the desired location. In the preferred embodiment the lines are also extended around the graft to subject it to radial compression simultaneously with its elongation. 
     A principal object of the invention is to provide an improved graft and system and method for its delivery and placement which enables the graft to be delivered through elongate body passages. 
     Another object of the invention is to provide an improved expansible tubular graft which may be fabricated with fluid permeable, or impermeable, walls. 
     Still another object is to provide such a graft which is biocompatible with the body and has means to securely anchor it in place. 
     A further object is to provide such a graft which may be securely placed with a main artery without blocking branch arteries, even where there is not a substantial length of healthy artery between the aneurysm being treated and the branch arteries. 
     Yet another more general object of the invention is to provide an improved apparatus and method for intraluminal delivery of a graft to a select remote area within a body passage, without need to surgically access the area. 
     Yet a further object of the invention is to provide an apparatus and method for the intraluminal placement of a graft within a body passage which may be carefully controlled to provide precise placement of the graft and repeatedly adjusted. 
     Still another object related to the latter object is to provide such an apparatus and method wherein the graft can be precisely located and fully expanded before its release from the delivery system. 
    
    
     These and other objects will become more apparent from the following detailed description and accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of the graft and delivery system. 
     FIG. 2 is an enlarged perspective view of the graft end of the delivery system shown in FIG. 1, with the graft in radially expanded condition. 
     FIG. 3 is an enlarged perspective view similar to FIG. 2, with the graft shown in a radially contracted condition. 
     FIG. 4 is an exploded side view of the delivery system, with parts shown in cross-section. 
     FIG. 5 is a side view of the delivery system and the sheath which may be used to introduce the system into an artery. 
     FIG. 6 is a side view of the sheath shown in FIG. 5, without the delivery system. 
     FIG. 7 is a perspective view of the sheath of FIGS. 5 and 6. 
     FIG. 8 is cross-sectional side view of the delivery system within an artery, with the graft shown in radially contracted condition. 
     FIG. 9 is a cross-sectional side view, with parts thereof broken away, showing the delivery system mechanism in the process of releasing the graft. 
     FIG. 10 is a cross-sectional side view showing the delivery system as it has fully released the graft within a body passage, at the commencement of removal of the system from the passage. 
     FIG. 11 is a cross-sectional side view showing an artery with an aneurysm and a graft with impermeable side walls which has been placed within the aneurysm according the present invention. 
     FIG. 12 is a cross-sectional side view showing an artery having a dissecting aneurysm; prior to treatment of the aneurysm through means of the graft of the present invention. 
     FIG. 13 is a cross-sectional side view of an artery corresponding to that of FIG. 12, diagrammatically showing how the lumen of the artery is forced open through a graft placed with the present invention. 
     FIG. 14 is a cross-sectional side elevational view of an artery which does not have a substantial length of healthy artery between itself and the renal arteries; showing a graft placed according to the present invention to treat any aneurysm within the artery while permitting flow to the renal arteries. 
     FIG. 15 is a cross-sectional view of the body, showing the thoracic and abdominal aorta and the manner in which the system of the present invention can be used to deliver grafts to select areas of the aorta. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows the graft and delivery system in exploded perspective, with the graft designated by the letter G and the delivery system designated in its entirety by letter S. The graft, as may be seen in FIG. 2, is of an open-ended tubular configuration and comprises filaments F 1 , and F 2  extending helically therearound. The filaments F 1 , and F 2  extend around the graft in opposite directions and cross at intersections I. The filaments are fabricated of a resilient material, such as polyester, titanium or stainless steel. The filaments cross over each other at intersections I. As a result of the resiliency of the filaments, the graft normally assumes a foreshortened enlarged diameter upon relaxation and, upon being elongated, assumes a reduced diameter condition (see FIG.  3 ). In a typical embodiment for use in treating a dissecting aneurysm in the aorta, the graft might have the following dimensions: 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 ELEMENT 
                 DIMENSION 
               
               
                   
                   
               
             
             
               
                   
                 Filament diameter 
                 .010 inches 
               
               
                   
                 Graft diameter in 
                 1.0-1.25 inches 
               
               
                   
                 the relaxed 
               
               
                   
                 condition 
               
               
                   
                 Graft length in the 
                 3.0-6.0 inches 
               
               
                   
                 relaxed condition 
               
               
                   
                   
               
             
          
         
       
     
     In a typical application, the graft is elongated to double its length for delivery, with the result that the outside diameter of the graft is reduced by substantially more than one-half. 
     The components of the delivery system may best be seen from FIG.  4  and comprise: 
     1. An outer tube  10  having an outer hub  12  fixed to its proximal end and a lateral opening  14  adjacent its distal end; 
     2. A middle tube  16  proportioned for slidable extension through the outer tube  10 , said middle tube having a middle hub  18  fixed to its proximal end and a lateral opening  20  adjacent its distal end; 
     3. A flexible distal retainer rod  22  proportioned for slidable extension through the middle tube  16 , said rod having a rod hub  24  fixed to its proximal end; 
     4. A closed loop flexible line  26  fixed at one end to the hub  24  and closed at its distal end  28 ; 
     5. A proximal suture loop retainer wire  30  proportioned for slidable extension through an opening  32  formed in one side of the hub  24  and through a passage  34  formed in the middle hub  18 , said retainer wire having a retainer hub  36  fixed to its proximal end; and, 
     6. A looped flexible line  38  fixed at its proximal end to the hub  36  and closed at its distal end  40 . 
     FIG. 1 shows the delivery system in the assembled condition, with the outer hub, middle hub and rod hub exploded relative to one another for purposes of illustration. The middle tube  16  extends slidably through the outer tube  10 . The retainer rod  22 , together with the looped flexible line  26  extends through the middle tube  16  and the closed distal end  28  of the line  26  extends through the opening  20  and around the graft G. The wire  30 , together with the looped flexible line  38 , extends through the opening  32  in the hub  24  and thence through the opening  34  in the hub  18  and through the hub  12  and the outer tube  10 . From the latter, it will be appreciated that there is sufficient space between the outer tube  10  and the middle tube  16  to accommodate free passage of the wire  30  and looped line  38  therethrough. The looped flexible line  38  exits the tube  10  through the opening  14  and extends around the graft G. 
     FIG. 2 shows in detail the manner in which the looped lines  26  and  38  extend around the graft G. As there shown, it will be seen that the looped line  38  is threaded into and out of the graft around its proximal end and exits from the graft to a closed end  40  engaged around the retainer wire  30 . The looped flexible line  26  is fed into and out of the graft G around its distal end and exits therefrom, with the end  28  engaged around the rod  22 . Thus, with the rod  22  and wire  30  in place as shown in FIG. 2, the looped ends of the lines  26  and  38  are secured around the distal and proximal ends, respectively, of the graft G. In this condition, movement of the hub  12  into mated engagement with the middle hub  18  functions to elongate the graft G and cinch the ends of the looped lines around the graft, as shown in FIG.  3 . Such elongation and cinching reduces the diameter of the graft by substantially more than one-half. 
     From FIG. 4 it will be seen that the hubs are configured to mate one within the other in a nested condition. Hub  12  has a recess  42  proportioned to receive a collar  44  formed on one end of the hub  18 . A collar  46  formed on the other end of the hub  18  is proportioned for mating engagement within a recess  46  formed in the hub  24 . The retainer hub  36  is formed with screw threads  48  formed for threaded engagement with a threaded opening  50  in the hub  18 . When the hubs are fully nested, the opening  32  is aligned with the opening  50  and the hub  36  is passed through the opening  32  into threaded engagement with the opening  50 . 
     FIG. 5 shows the delivery system fully assembled, with the hubs nested together and the graft G in the fully elongated reduced diameter condition. As there shown, the graft is in the process of being introduced into the femoral artery  52  through a partially split sheath  54 . The sheath has a length equal to or slightly greater than that of the delivery system and, during the delivery process, fully encloses that part of the system disposed within the artery. Once fully in place at the site where it is desired to locate the graft, the sheath is partially withdrawn, as shown in FIG. 5, to expose the graft. 
     FIGS. 6 and 7 show the detailed construction of the sheath. The sheath is preferably made of a flexible material having a relatively low coefficient of friction, such as polyethylene or TEFLON. The proximal end of the sheath, designated  56 , is of an open funnel-shaped configuration with a slit  58  extending over its length. The distal end of the sheath, designated  60 , is of a closed conical configuration with a slit  62  extending thereacross to permit the delivery system to be passed therethrough, as shown in FIG.  5 . 
     The graft G may be either fluid permeable or impermeable, or a combination of permeable and impermeable portions, depending upon the area of its intended use. Permeability naturally results from the spacing of the filaments F 2 . Impermeability may be provided by coating the graft with an elastomer, such as silicone. 
     Operation 
     The operation of the graft and delivery system may be seen from FIGS. 8,  9  and  10 . In FIG. 8, the graft is shown in the elongated contracted condition, with the sheath retracted prior to expansion and release of the graft from the delivery system. Expansion is provided by moving the hub  12  forwardly away from the hub  18  which, in turn, moves the distal end of the outer tube  10  toward the distal end of the middle tube  16  (See FIG. 9) and permits the graft to foreshorten and expand into engagement with the artery. If the graft is not positioned at the precise location desired, it may be re-elongated by moving the hub  12  into engagement with the hub  18  and repositioned. Once the graft is expanded at the precise location desired, it is released from the delivery system by first withdrawing the wire  30  and the flexible line  38  and then withdrawing the rod  22  and the flexible line  26 . Withdrawal of the wire  30  and the rod  22  releases the looped distal ends  40  and  28  of the lines. Once the lines are so released, proximal pulling of the lines (See FIG. 10) pulls the lines from the graft and out of the delivery system. The remaining components of the system can then be fully withdrawn from the artery through the groin incision. The sheath  54  may be left in place to facilitate such withdrawal. 
     The graft may also be provided with barbs B for engagement with the body passage within which the graft is used. Such barbs, as shown in FIG. 2, may comprise folded-over titanium staples passed through the material of the graft. 
     FIGS. 11,  12 ,  13  and  14  show different applications of the graft. In FIG. 11, an impermeable coated form of the graft G is shown within an artery A 1  at the site of an aneurysm which is shielded by the graft. The coating on the graft is designated by the letter C. FIG. 12 shows an artery A 2  having a dissecting aneurysm  64 . FIG. 13 shows the same artery A 2  with its lumen forced open by a permeable form of the graft, designated G 1 . In this application, the permeable character of the graft permits blood to flow from the artery A 2  into the branches A 3 . The arrow lines in FIGS. 12 and 13 depict the direction of the flow of blood. As shown in FIG. 13, the graft G, compresses the aneurysm and permits free flow through the artery. FIG. 14 shows an artery A 4  having an aneurysm  66  without a substantial length of healthy artery between the aneurysm and renal arteries  68 . As there shown, a graft G 2  having an impermeable portion  70  and a permeable portion  72  is used. The impermeable portion  70  is positioned over the aneurysm  66  and adjacent healthy tissue and the permeable portion  72  is placed over the renal arteries  68  and adjacent healthy tissue of the artery A 4 . Thus, the graft bridges the aneurysm and the renal arteries, allowing flow through all arteries and providing for positive graft fixation. 
     FIG. 15 shows the manner in which the graft may be inserted into the femoral artery through a groin incision and directed to treat a dissecting thoracic aneurysm, such as that shown in FIGS. 12 and 13, or an abdominal aortic aneurysm. Dashed lines  74  depict where the graft would be positioned for treating a dissecting thoracic aneurysm. Dashed lines  76  depict where the graft would be positioned for treating an abdominal aortic aneurysm. Because of the side branches at the thoracic aneurysm, the permeable embodiment of FIG. 13 would be used at that location. The abdominal aortic aneurysm would be treated with the impermeable graft embodiment of FIG.  11 . 
     CONCLUSION 
     From the foregoing description, it is believed apparent that the present invention enables the attainment of the objects initially set forth herein. In particular, a graft and delivery system is provided which may be delivered to remote locations to treat various types of aneurysms. It should be understood, however, that the invention is not intended to be limited to the illustrated embodiment, but rather is defined by the accompanying claims.