Check valve for intraluminal graft

An intraluminal graft assembly is provided with a double ball check valve which is normally urged to a closed position by a single compression spring acting on a first ball to urge it into sealing engagement with a valve seat. A spacer between the first ball and the second ball urges the second ball into sealing engagement with a second valve seat when the first valve is in sealing engagement with its associated valve seat. A threaded coupler engages and displaces the second valve axially out of engagement with its associated valve seat carrying with it the spacer and first ball thereby displacing also the first ball out of engagement with its associated valve seat. The double ball check valve permits the introduction of fluid into and removal of fluid from the cavity defined by inner and outer wall members of an intraluminal graft member.

BACKGROUND OF THE INVENTION 
The present invention relates an intraluminal graft assembly and more 
specifically a dual-ball check valve for the graft member of such 
assembly, The check valve provides means for conveying fluid into the 
space or cavity defined by the spaced apart walls and ends of the graft 
member to facilitate proper positioning and placement of the intraluminal 
graft assembly in the blood vessel of a patient. 
The use of the stents and grafts in repairing diseased or damaged blood 
vessels is well know and is particularly beneficial in repairing the 
aortic aneurysms. As a result of miniaturization of the grafts and stents, 
it has been possible to implant such grafts and stents without invasive 
surgery which requires opening of the abdominal and/or chest cavity for 
repair of the aorta or other blood vessels in that area. 
Treatment of aneurysms through non-invasive procedures is well known in the 
art and is disclosed in the following prior art patents: U.S. Pat. Nos. 
4,740,207, 5,156,620, 4,577,631, 4,776,337, 4,787,899 and 5,330,528. 
The graft prosthesis may consist of a double-walled cylinder made of 
extruded polytetrafluoroethylene (ePTFE) or other suitable biocompatible 
material, and sealed at the ends creating a closed space between the inner 
and outer walls and the opposing ends and an open lumen for blood flow 
defined by the inner surface of the inner wall. The graft prosthesis is 
collapsed during the insertion and implantation procedure. Thus, the 
collapsed graft prosthesis will be inserted in a remote vessel such as the 
femoral artery and directed to the desired repair site, for example the 
aorta, by means of a catheter. Upon reaching the site of the damaged 
vessel to be repaired, fluid such as air or a saline solution is 
introduced into the cavity defined by the inner and outer walls joined at 
their opposite ends to expand the graft prosthesis to a position such that 
the exterior surface of the outer wall adjacent the opposing ends contacts 
and becomes sealingly engaged to the inner surface of the blood vessel. 
SUMMARY OF THE INVENTION 
The present invention includes a dual-ball check valve for an intraluminal 
graft prosthesis which permits the introduction of fluids from a remote 
location outside of a patient's body into the cavity of a graft which has 
been positioned in a blood vessel such as the aorta, remote from the site 
of entry into the body for example, the femoral artery. After the 
introduction of fluid such as saline solution into the cavity, the surgeon 
will make a determination of whether the graft has been properly 
positioned in the precise location for optimal benefit to the patient. The 
intraluminal graft assembly of the present invention permits the surgeon, 
if he determines that a slight repositioning of the graft is necessary or 
desirable, to remove a sufficient amount of the saline solution or other 
fluid from the cavity to permit appropriate repositioning of the graft 
prosthesis assembly. In addition, the valve effectively prevents leakage 
of such fluid following final positioning and implantation of the graft in 
the blood vessel. 
Accordingly, it is an object of the present invention to provide a graft 
assembly having suitable valve means for introduction of fluid into the 
cavity defined by the graft member and for removal and reintroduction of 
such fluid as necessary during the implantation procedure, and which will 
provide a leak-proof seal following a final positioning and implantation 
of the graft assembly. 
The intraluminal graft assembly prosthesis of the present invention 
comprises a dual-ball check valve secured to the graft member for 
retention therewith following implantation in the blood vessel. The graft 
member, formed of a suitable bio-compatible material, has inner and outer 
walls joined together at their respective adjoining ends to form a cavity 
when the graft member is in the expanded condition. The dual-ball check 
valve is of sufficiently small size to permit introduction of the graft 
assembly prosthesis into the patient through a remote blood vessel and 
includes a plurality of body members joined together with two of the body 
members having valve seats each of which is contoured to be sealingly 
engaged by a ball. A spring yieldingly urges one ball, preferably formed 
of rubber, into sealing engagement with its associated valve seat of the 
first body member. A spacer is positioned between the balls and is of a 
length such as to cause the second ball, preferably formed of stainless 
steel, to sealingly engage its associated valve seat of the second body 
member when the first ball is sealingly engaged to its valve seat of the 
first body member. The second body member of the check valve has an 
internally threaded portion which extends out of the graft member. 
A threaded coupler has an extension portion which engages the second ball 
upon being threadedly engaged to the second body member. Continued 
threading of such coupler inwardly and the axial movement resulting 
therefrom causes the extension portion to engage and then displace the 
second ball away from and out of engagement with the valve seat of the 
second body member. Such movement of the second ball is transmitted to the 
first ball by means of a spacer thereby moving such first ball out of 
engagement with its associated valve seat and opening the check valve for 
the introduction of fluid into or removal of fluid from the cavity of the 
graft member. 
The present invention also provides a method for implanting an intraluminal 
graft assembly which permits positioning of the graft member at a remote 
site to be repaired, the introduction of fluid into the cavity of the 
graft member, the subsequent removal of fluid from such cavity, 
repositioning of the graft member and final introduction of fluid into 
such cavity.

DESCRIPTION OF THE INVENTION 
Referring to the drawings, there is shown an intraluminal graft assembly 10 
for use with a threaded coupler member 80 for introducing saline solution 
or other fluid into the graft assembly 10. The graft assembly 10 includes 
a graft member 14 and a check valve generally designated manufactured of a 
suitable bio-compatible material well known in the art, such as for 
example, extruded polytetrafluoroethylene (ePTFE) and includes an outer 
cylindrical wall 15 and an inner cylindrical wall 16 joined at opposing 
ends 17 and 18. The outer wall 15 has a larger diameter than the inner 
wall 16 such that when the respective outer wall 15 and inner wall 16 are 
at their maximum sizes, they, along with the ends 17 and 18 define a 
cavity 19. As will be described in greater detail, the check valve 20 is 
permanently secured in the cavity 19 by adhesive or other suitable means 
joining it to the outer wall 15 and the inner wall 16. 
The graft member 14 may be collapsed to a size permitting it and the check 
valve 20 secured thereto to be introduced into a remote blood vessel and 
moved through such blood vessel to the aorta or other damaged vessel 
intended to be repaired with the intraluminal graft assembly. Upon 
positioning at the site of the blood vessel to be repaired, fluid may be 
introduced into the cavity 19 through the valve 20 from the coupler 80 and 
hose 89 associated therewith to expand the graft member 14 to its full 
size shown in FIG. 1. When so expanded to its full size, the outer wall 15 
in the areas adjacent the respective ends 17 and 18 will engage and be 
secured to the wall of the blood vessel being repaired with the central 
portion of the graft member 14 between such ends 17 and 18 spanning the 
damaged or diseased portion of the blood vessel. When the graft member 14 
is thus expanded, the innermost surface 13 of the inner wall 16 defines an 
open lumen for the flow of blood. 
Referring now to FIGS. 2 through 4, the check valve includes a spring guide 
member 30 joined to a first or rear body member 40 which in turns is 
joined to a second or outer body member 50. The joined body members 30, 40 
and 50, extend along an axis A and, when opened, define passageways for 
the flow of fluid therethrough. 
The spring guide member 30 extends from an inner end 32 to an outer end 33 
and has a central passageway 31 extending therethrough. The spring guide 
member 30 is provided with an outwardly facing annular groove 34 intended 
to receive a suitable adhesive for affixing to the outer wall 15 and inner 
wall 16 of graft member 14. The spring guide member 30 is provided with a 
cylindrical wall portion 35 of a predetermined diameter on the opposite 
side of the groove 34 from the inner end 32 and a reduced size cylindrical 
wall portion 36 defining a spring guide between the cylindrical wall 
portion 35 and the outer end 33. The cylindrical wall portion 35 is joined 
to the reduced size cylindrical wall portion by a shoulder 37. 
The first or rear body member 40 extends from an inner end 41 to an outer 
end 42 and includes an extremely thin wall section 43 extending from the 
inner end 41 to an area having an inwardly tapering conical surface 
defining a valve seat 44. A passageway 45 extends along the axis A from 
the valve seat 44 to the outer end 42. If desired, the outer end 42 may be 
provided with a lead-in surface 46 tapering inwardly toward the axis and 
toward the inner end 41. 
The inner surface of that portion of the thin walled section 43 in the area 
adjacent the inner end 41 is sealingly adhered to the cylindrical wall 
portion 35 of the spring guide member 30. The first body member 40 thus 
cooperates with the spring guide member 30 to define a cavity 47 in which 
is positioned a compression spring 24, a pusher 60 and a first ball 22. 
The first ball 22 is sized for sealing engagement with the valve seat 44 
and, thus, significantly larger in diameter than the passageway 45. The 
first ball 22 is preferably made of rubber such as Fluorel obtained from 
3M Company and has a Durometer of 75 to 80 Shore A to provide an effective 
seal with the valve seat 44 capable of sealing water at 10 psig. It is 
within the contemplation of the invention, however, that the first ball 
could be stainless steel or other metal suitable for implantation in the 
human body. The pusher is located on the opposite side of the first ball 
22 from the valve seat 44. The pusher 60 has a cylindrical wall 61 with an 
outer surface sized to be slidingly received in the cavity 47 in close 
engagement with the inner surface of the thin walled section 43. The 
pusher 60 extends from an inner end 62 to an outer end 66 having an 
outwardly tapering wall portion defining a ball seat 63. A central 
passageway 64 extends from the inner end 62 to the ball seat 63. The 
cylindrical wall 61 is provided with one or more slots 65 which permit 
fluid to flow therethrough even though the ball 22 is engaged to the ball 
seat 63. 
A compression spring 24 encircles the reduced cylindrical portion 36 of the 
spring guide member 30 and has one end engaging the shoulder 37 between 
the cylindrical wall portion 35 and reduced cylindrical wall 36. The 
spring 24 extends beyond the outer end 33 of the spring guide member 30 
and engages the inner end 62 of the pusher 60. Thus, the compression 
spring 24 yielding urges the pusher 60 to a position causing the first 
ball 22 to be sealingly engaged to the valve seat 44. 
The first body member 40 is provided with outwardly facing annular groove 
48 for receiving glue for adhering that portion of the check valve to the 
outer wall 15 and inner wall 16 of the graft member 14. 
The second body member 50 extends from an inner end 51 to an outer end 52. 
The second body member 50 has a thin walled section 53 in the area 
adjacent the inner end 51, the inner surface of which is sealingly engaged 
to the outer surface of the first body member 40 adjacent its outer end 
42. 
In an area generally centrally positioned between the inner end 51 and the 
outer end 52, the inner surface of the second body member 50 tapers 
inwardly toward the axis A and toward the outer end 52 to define a valve 
seat 54. Preferably the valve seat 54 defines a section of a cone. In the 
area between the valve seat 54 and the outer end 52 is a short inwardly 
facing cylindrical section 55 followed by an enlarged threaded section 56. 
A further enlarged inwardly facing cylindrical wall section 57 extends 
between the threaded section 56 and the outer end 52. An outwardly facing 
annular groove 58 is provided in an area of the second body member 50 in 
the vicinity of the short inwardly facing cylindrical section 55. As can 
be seen in FIGS. 1 and 5, the outer end 52 and a short portion of the 
second body member 50 adjacent thereto extends outwardly through an 
aperture 11 in the end 18 of the graft member 14. 
Positioned in the cavity between the valve seat 54 and the outer end 42 of 
the first body member 40 is a second ball 23 having a diameter larger than 
the diameter of the short inwardly facing cylindrical section 55 and sized 
to become sealingly engaged with the valve seat 54. Preferably, the second 
ball is formed of stainless steel or other suitable metal; however, it 
could be formed of rubber similar to that of the first ball. 
Positioned in the space between the first ball 22 and second ball 23 is a 
spacer 70 having an axial passageway 71. The spacer 70 extends from an 
inner end 72 abutting the first ball 22 to an outer end 73 abutting the 
second ball 23 and has a length such that when the first ball 22 is in 
sealing engagement with the valve seat 44 of the center body member 40, 
the second ball 23 will be in sealing engagement with the valve seat 54 of 
the outer member 50. The spacer 70 is provided with one or more slots 74 
extending through the side wall and extending inwardly from the inner end 
72 and one or more of the slots 75 extending through the side wall and 
extending to the outer end 73. As a result of the slots 74 and 75, 
engagement of the balls 22 and 23 with the respective inner end 72 and 
outer end 73 does not create a seal. Thus, the passageway 71 is always 
open to the flow of fluid between the slots 74 and 75. As a result, when 
the first ball 22 is disengaged from the valve seat 44 of the first body 
member 40 and the second ball 23 is disengaged from the valve seat 54 of 
the second body member 50, fluid may flow through the slots 75, passageway 
71 and the slots 74 and on through the space between the first ball 22 and 
valve seat 44 of the center body 40, through the slots 65 of the pusher 
60, through its passageway 64, through the passageway 31 of the spring 
guide member 30, and into the cavity 19 of the graft member 14. 
The intraluminal graft assembly 10 thus far described is intended to be 
positioned in and remain permanently in a damaged blood vessel. As such 
all members must be manufactured of a biocompatible material such as a 
stainless steel (304) or a suitable plastic. 
In order to expand the intraluminal graft assembly 10 from its collapsed or 
folded condition required for movement through the veins and positioning 
at the damaged site to its expanded condition forming cavity 19, there is 
provided a coupler 80 which extends from an inner end 81 to an outer end 
82. The coupler has a passageway 83 extending from the inner end 81 to the 
outer end 82 and an extension portion 84 having an exterior cylindrical 
wall adjacent the inner end 81 sized to be received in the short inwardly 
facing cylindrical section 55 of the second body member 50. One or more 
slots 85 is formed in the extension portion 84 and extends from the inner 
end 81 toward the outer end 82. As a result of the slots 85, there will be 
no sealing engagement between the coupler 80 and its extension 84 when the 
inner end 81 engages the second ball 23. 
The coupler 80 is also provided with a threaded section 86 for engagement 
with the threaded section 56 of the second body member 50 and an annular 
groove 87 in which is positioned an annular sealing ring 26 for providing 
a fluid tight seal when the coupler 80 is engaged to the second body 
member 50. If desired, the coupler 80 may be provided with an enlarged 
shoulder 88 sized to engage the outer end 52 of the second body member 50 
to limit the extent to which the coupler 80 may extend into the second 
body member 50. 
As can be readily seen from comparing FIGS. 2 and 3, when the inner end 81 
of the coupler 80 is disengaged or Out of contact with the second ball 23, 
the second ball 23 will be sealingly engaged with the valve seat 54 of the 
second body member 50 and the first ball 22 will be in sealing engagement 
with the valve seat 44 of the first body member 40. Rotation of the 
coupler 80 in a direction further inwardly causes the inner end 81 to move 
the second ball 23 axially thereby displacing it out of engagement with 
the valve seat 54. Such movement of the second ball 23 moves the spacer 70 
axially in the same direction which, in turn, moves the first ball 22 
axially out of engagement with valve seat 44 carrying with it the pusher 
60 against the yielding pressure exerted by spring 24. This is the 
position shown in FIG. 3 which shows the valve 20 in the fully open 
position, thereby permitting fluid to flow through the passageway 83 and 
slots 85 of the coupler 80, through the gap between the second ball 23 and 
the valve seat 54, through the slots 75, passageway 71 and slots 74 of the 
spacer 70, through the space between the first ball 22 and the valve seat 
44, through the slots 65 and passageway 64 of pusher 60 and through the 
passageway 31 and into the cavity 19 of the graft member 14. When the 
valve 20 is in the open position of FIG. 3, fluid may also be removed from 
the cavity 19 simply by applying a negative pressure at the outer end 82 
of the coupler 80 through the hose 89. 
Referring now to FIGS. 5 and 6, it may be seen how the check valve 20 is 
retained in the graft member 14, only a fragment of which is shown. As 
previously described, the check valve 20 extends through an aperture 11 in 
the end 18 and extends into the cavity 19 defined by the gap between the 
outer wall 15, inner wall 16 and ends 17 and 18 of the graft member 14. An 
appropriate adhesive 78 is applied throughout the length of the valve 20 
and to the adjacent portions of the surfaces of the outer wall 15 and 
inner wall 16 facing the cavity 19. Although the thickness is shown in 
FIGS. 5 and 6 for illustration purposes as fairly thick, in reality it is 
applied as a very thin film except in the areas of the grooves 34, 48 and 
58 where it desirably fills such grooves. A suitable adhesive is a heat 
activated adhesive sold under the brand name of Chemlok by Lord 
Corporation, 2000 West Grandview Blvd., Erie, Pa. After the check valve 20 
is properly positioned in the graft member 14 as shown in FIGS. 5 and 6, 
the adhesive 78 may be subjected to heat thereby activating the adhesive 
and causing it to firmly secure the check valve 20 to the graft member 14. 
Many modifications will become apparent to those skilled in the art. 
Accordingly, the scope of the present invention should be measured only by 
the scope of the claims appended hereto.