Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
1999-02-26
2001-06-19
Mancene, Gene (Department: 3732)
Surgery
Instruments
Internal pressure applicator
C623S001110, C604S096010
Reexamination Certificate
active
06248122
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention provides devices and methods for the endoluminal placement of prostheses, particularly within the vascular system for the treatment of cardiovascular disease, such as vascular stenoses, dissections, aneurysms, and the like. The apparatus and methods, however, are also useful for placement in other body lumens, such as the ureter, urethra, biliary tract, gastrointestinal tract and the like, for the treatment of other conditions which may benefit from the introduction of a reinforcing or protective structure within the body lumen. The prostheses will be placed endoluminally. As used herein, “endoluminally” will mean placement by percutaneous or cutdown procedures, wherein the prosthesis is translumenally advanced through the body lumen from a remote location to a target site in the lumen. In vascular procedures, the prostheses will typically be introduced “endovascularly” 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 femoral artery, or brachial and subdlavian arteries, for access to the target site.
An endoluminal prosthesis typically comprises at least one radially expansible, usually cylindrical, body segment. By “radially expansible,” it is meant that the body segment can be converted from a small diameter configuration (used for endoluminal placement) to a radially expanded, usually cylindrical, configuration which is achieved when the prosthesis is implanted at the desired target site. The prosthesis may be non-resilient, e.g., malleable, thus requiring the application of an internal force to expand it at the target site. Typically, the expansive force can be provided by a balloon catheter, such as an angioplasty balloon for vascular procedures. Alternatively, the prosthesis can be self-expanding. Such self-expanding structures are provided by a temperature-sensitive superelastic material, such as Nitinol, which naturally assumes a radially expanded condition once an appropriate temperature has been reached. The appropriate temperature can be, for example, a temperature slightly below normal body temperature; if the appropriate temperature is above normal body temperature, some method of heating the structure must be used. Another type of self-expanding structure uses resilient material, such as a stainless steel or superelastic alloy, and forming the body segment so that it possesses its desired, radially-expanded diameter when it is unconstrained, e.g., released from radially constraining forces a sheath. To remain anchored in the body lumen, the prosthesis will remain partially constrained by the lumen. The self-expanding prosthesis can be delivered in its radially constrained configuration, e.g. by placing the prosthesis within a delivery sheath or tube and retracting the sheath at the target site. Such general aspects of construction and delivery modalities are well-known in the art and do not comprise part of the present invention.
The dimensions of a typical endoluminal prosthesis will depend on its intended use. Typically, the prosthesis will have a length in the range from 0.5 cm to 10 cm, usually being from about 0.8 cm to 5 cm, for vascular applications. The small (radially collapsed) diameter of cylindrical prostheses will usually be in the range from about 1 mm to 10 mm, more usually being in the range from 1.5 mm to 6 mm for vascular applications. The expanded diameter will usually be in the range from about 2 mm to 30 mm, preferably being in the range from about 3 mm to 15 mm for vascular applications.
One type of endoluminal prosthesis includes both a stent component and a graft component. These endoluminal prostheses are often called stent grafts. A stent graft is typically introduced using a catheter with both the stent and graft in contracted, reduced-diameter states. Once at the target site, the stent and graft are expanded. After expansion, the catheter is withdrawn from the vessel leaving the stent graft at the target site.
Grafts are used within the body for various reasons, such as to repair damaged or diseased portions of blood vessels such as may be caused by injury, disease, or an aneurysm. It has been found effective to introduce pores into the walls of the graft to provide ingrowth of tissue onto the walls of the graft. With larger diameter grafts, woven graft material is often used. In small diameter vessels, porous fluoropolymers, such as PTFE, have been found useful.
Coil-type stents can be wound about the catheter shaft in torqued compression for deployment. The coil-type stent can be maintained in this torqued compression condition by securing the ends of the coil-type stent in position on a catheter shaft. The ends are released by, for example, pulling on wires once at the target site. See, for example, U.S. Pat. Nos. 5,372,600 and 5,476,505. Alternatively, the endoluminal prosthesis can be maintained in its reduced-diameter condition by a sleeve; the sleeve can be selectively retracted to release the prosthesis. A third approach is the most common. A balloon is used to expand the prosthesis at the target site. The stent is typically extended past its elastic limit so that it remains in its expanded state after the balloon is deflated. One balloon expandable stent is the PALMAZ-SHATZ stent available from the CORDIS Division of Johnson & Johnson. Stents are also available from Arterial Vascular Engineering of Santa Rosa, Calif. and Guidant Corporation of Indianapolis, Ind.
SUMMARY OF THE INVENTION
The present invention simplifies the release of at least one portion of an endoluminal prosthesis, such as a stent, a graft, a stent graft or other endoluminal structure having mechanical scaffolding sufficient to maintain patency, from a catheter shaft by using the inflation of a balloon to release the one prosthesis portion from the catheter shaft. The endoluminal prosthesis is optionally delivered to the target site within an introducer sheath. At least one other prosthesis portion may be selectively released by the user, typically using a mechanical element such as a push wire. Reducing the number of push wires or other release mechanisms simplifies the construction of the catheter. By selectively permitting one prosthesis portion, typically an end of a stent, to expand before the entire prosthesis is permitted to expand, the prosthesis can be located at the target site more precisely than possible with conventional techniques. The invention also results in no or substantially no foreshortening of the prosthesis during deployment. The invention permits controlled release of the prosthesis and permits the prosthesis to be repositioned if initially out of position.
A catheter is used to place the prosthesis at a target site within the body, typically within a blood vessel. The catheter preferably includes a catheter shaft having a distal portion and defining an inflation lumen. An inflatable balloon is preferably fluidly connected to the inflation lumen and typically surrounds the catheter shaft at its distal portion. A stent or other prosthesis, having first and second ends, surrounds the balloon. Graft material, typically in the form of porous PTFE or ePTFE, is used in the case of a stent graft. The graft material preferably surrounds the stent, or is positioned within and is attached to the stent, or is both positioned within and surrounding the stent.
The prosthesis has portions, typically ends, which are removably secured to the catheter shaft. When the prosthesis includes a stent, the stent may be of any conventional or other design; the stent is typically a coil-type stent having first and second distal ends. The ends of the stent are, in one preferred embodiment, slidably housed within first and second stent end holders carried by the catheter shaft. The first stent end holder is designed so that upon inflation of the balloon, the first stent end is released from the first stent end holder by the act of inflating the balloon. The second stent end i
Fogarty Thomas J.
Kamdar Kirti P.
Klumb Katherine J.
Hann James F.
Haynes & Beffel LLP
Mancene Gene
Priddy Michael B.
Vascular Architects, Inc.
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