« PreviousContinue »
United States Patent  [ii] Patent Number: 5,741,325
Chaikof et al.  Date of Patent: Apr. 21, 1998
U.S. Patent Apr. 21,1998 sheet 1 of 2 5,741,325
U.S. Patent Apr. 21,1998 sheet 2 of 2 5,741,325
 SELF-EXPANDING INTRALUMINAL COMPOSITE PROSTHESIS
 Inventors: Elliot L. Chaikof, Dunwoody; Peter J. Ludovice, Atlanta, both of Ga.
 Assignees: Emory University; Georgia Tech
Research Corp., both of Atlanta, Ga.
 Appl. No.: 657,975
 Filed: May 3,1996
Related U.S. Application Data
 Continuation of Ser. No. 131,156, Oct 1, 1993, abandoned.
 Int Cl.fi A61F 2/06; A61F 2/04
 U.S. CI 623/1; 623/12
 Field of Search 623/1, 11, 12;
606/194, 195,198,191, 193, 152, 153, 155, 158; 600/36
 References Cited
U.S. PATENT DOCUMENTS
FOREIGN PATENT DOCUMENTS
1205743 9/1970 United Kingdom 623/1
Primary Examiner—Debra S. Brittingham
Attorney, Agent, or Firm—Needle & Rosenberg, P.C.
This invention relates to a self-expanding intraluminal composite prosthesis comprised of a rigid reinforcing component and sealing component. The prosthesis may be fabricated as either a straight or bifurcated tubular structure and is applicable to the treatment of any bodily passage including, but not limited to, vascular applications, e.g., aneurysms, arteriovenous fistulas, as well as stenotic regions of the peripheral circulation which have been percutaneously dilated but are at high risk for restenosis. The major attributes of this prosthesis can include the use of a unique multilayered biaxial braid which thereby creates a homogeneously blended composite with isotropic deformation and expansion characteristics and an associated high contraction ratio. The use of multiple layers allows for the fabrication of a device of varied porosity while retaining adequate tensile or mechanical wall strength.
4,994,701 2/1991 MacGregor
5,366,504 11/1994 Andeisen et al.
22 Claims, 2 Drawing Sheets
This application is a continuation of application Ser. No. 08/131,156, filed Oct. 1, 1993 which status is abandoned.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to intraluminal prosthetic devices. In particular, this invention relates to self-expanding intraluminal composite prosthetic devices for use, e.g., in endovascular applications.
2. Background Art
Since 1975, vascular prostheses composed of either knitted or woven Dacron® fibers or expanded PTFE (GoreTex®) have been established standards in anastomotic surgical arterial reconstruction. In the past decade, however, a steady growth of non-surgical transcatheter techniques and related devices have broadened both potential applications and overall suitability of endovascular reconstruction. In particular, angioplasty with or without endovascular stent placement has become an accepted adjunct in the management of atherosclerotic occlusive disease.
In the past, aneurysmal aortic disease has been treated almost exclusively by resection and surgical graft placement Recently, however, successful preliminary tests have been reported for transfemoral endovascular grafting as an alternative therapeutic option. In contrast to standard surgical repair, the use of an endovascular device does not entail the removal of the diseased aorta, but serves to create a conduit for blood flow in the event of subsequent aneurysm rupture. It has been postulated that an endovascular graft may, as a secondary effect, lower the rate of aneurysm expansion and late rupture via a reduction of hemodynamically induced wall stresses. Endovascular aortic prostheses under current commercial development consist almost exclusively of grafts and stents attached together to form a single device. The stent secures the graft in a desired position and reduces the risk of late prosthetic migration.
There are presently two classes of stents in widespread clinical use categorized with respect to their mode of expansion: balloon expandable and self expanding. Balloon expandable stents typically consist of slotted or wire mesh tubes that can be permanently expanded after operator controlled balloon inflation. At least four U.S. patents have been granted (see, Palmaz: U.S. Pat. Nos. 4.739.762; 4,739, 762; 4,776.337; and 5,102,417 and Strecker, E. P.; Iiermann, D.; Barth, K. H.; Wolf, H. R. D.; Freudenberg, N.; Berg. G.; Westphal, M.; Tsikuras, P.; Savin, M.; and Schneider, B., Radiology, 175, 97-102 (1990)). Characteristically, self-expanding stents are loose wire meshes that can be compressed inside a sheath which, when removed, allows the stent to expand without the use of an inflating balloon. Many models are in common use including the MEDINVENT® stents, (see, Jedwab, M. R. and Clerc, C. O. J. Appl. Biomater, 4, 77-85 (1993) and Gianturco, Yoshioka, T.; Wright, K.; Wallace, S.; Lawrence Jr.. D. D.; Gianturco, C. Amer. J. Radiology, 151. 673-676 (1988)).
Recently, Nitinol has been suggested as an alternative to stainless steel which has been the standard stent fabrication material (see, Balko, A.; PiasecM, G. J.; Shah, D. M.; Carney, W. I.; Hopkins. R. W. and Jackson. B. T, J. Surg. Res., 40, 305-309 (1986)). This nickel titanium alloy, also called "memory metal", will assume its original annealed shape when heated above a particular temperature. The
ability to produce devices of smaller cross-sectional area (flow profile) is its major advantage. Nonetheless, it has two major disadvantages. Nitinol requires irrigation with cold saline solution during placement to prevent premature 5 expansion. Additionally, its anisotropic expansion may cause damage to the vascular wall.
Most stent delivery systems are based on multi-sheath catheters. Self-expanding stents are deployed when the outer sheath of the catheter is retracted. The stent expands and the 10 catheter is withdrawn. Balloon expandable stents are seated on an angioplasty balloon. After the sheath is removed, the balloon is inflated to deploy the stent. Catheter delivery systems have only recently been used to deploy grafts, but follow the same principles outlined above.
Commercially available vascular grafts for surgical applications are typically composed of polyethyleneterepthalate (DACRON®) fibers or extruded polytetrafluoroethylene (GORE-TEX®). Woven and knitted grafts are crimped in an accordion-like fashion along their circumference to prevent "kinking" when traversing curves or bends. Mechanistically, crimping allows the graft to expand longitudinally but limits radial contraction. Weave patterns and their associated porosity and handling characteristics for sutured anastomoses remains the major difference among graft types (see, Dumicans, U.S. Pat. No. 4,923,470; and Raster, U.S. Pat. No. 4,441,215). Such devices are not suitable for endovascular applications although woven and knitted DACRON® grafts have been tried for endovascular grafting. Crimping appears necessary to reduce kinking but Emits the compressibility and cross-sectional flow profile of the device.
The incorporation or "healing" of a fabric-based vascular prosthesis may depend, in part, on an optimal porosity of the prosthesis (see, Snyder, R. W. and Botzko, K. M. from 35 Biologic and Synthetic Vascular Prosthesis, edited by J. C. Stanley, Grune and Stratton: New York, (1982), pp. 485^194; and Turner, R. J., Hoffman, H. L., Weinburg, S. L. from Biologic and Synthetic Vascular Prostheses, edited by J. C. Stanley, Grune and Stratton: New York, (1982), pp. 40 509-522). Wesolowski and co-workers reported that increased porosity was associated with a reduction in graft calcification (WesolowsM, S. A., Liebig, W. J., Karlson, K. E., et al., Surgery, 50, 91-100 (1961)). As an outgrowth of this work, the vascular graft industry pursued, for a time, the 45 goal of an ultrathin. highly porous graft. This approach was abandoned after mechanical failure plagued these grafts (see, Ottinger. L. W. Darling, R. C. Werthlin. L. S.. et al., Arch. Surg. Ill, 146-149 (1976)).
Sutureless grafts for vascular reconstruction were 50 reported and patented as early as the 1960's as an alternative to standard operative aortic repair. In the 1980's, percutaneous transcatheter techniques grew in popularity and the concept of sutureless grafting was reintroduced as an endovascular approach to occlusive and aneurysmal disease. A 55 triple layered air-inflatable graft has been patented, but the potential for failure appears substantial because of the complex arrangement of membranes, valves, and seals (Pigott, U.S. Pat. No. 5,156,620). Sutureless endovascular prostheses have otherwise included: (i) graft/staple; (ii) 60 graft/hook; and (iii) graft/stent combinations.
Graft/staple combinations are covered by two U.S. patents in which a balloon catheter system delivers a standard vascular graft with staples lodged in the end of the graft (Lazaras. U.S. Pat. Nos. 4,787,899 and 5,104,399). The 65 inflation of the balloon implants the staples into the vascular wall, thereby securing the graft. Two additional patents exist for graft/hook combinations (Kornberg, U.S. Pat. Nos.