Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent combined with surgical delivery system
Reexamination Certificate
1997-11-14
2002-09-10
Thaler, Michael H. (Department: 3731)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent combined with surgical delivery system
C606S108000
Reexamination Certificate
active
06447540
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to medical devices and procedures for using such devices and, more particularly, to devices which are introduced into a vessel, cavity, or duct in a human or veterinary patient.
BACKGROUND OF THE INVENTION
Catheters have long been used in a wide variety of medical procedures for establishing, reestablishing or maintaining passages, cavities, or lumens in vessels, organs or ducts in human and veterinary patients. Such vessels and the like include those of the vascular system, the biliary tract (including the common bile and other ducts) and the urinary tract (including the kidney, the bladder, the ureters and the urethra), as well as the esophagus, the trachea, the intestines, the colon, the rectum, the sinus tract, the fallopian tubes, the cervix and the vagina, among others. All of these may be subject to stricture or narrowing which requires dilation. For example, blood vessels can be blocked or narrowed by arteriosclerosis (atherosclerosis), while esophageal strictures can arise from individual anatomical differences, or from diseases such as connective tissue disorder or cancer.
Catheters useful for dilating or enlarging regions in such vessels and the like often include a nondistending, inflatable balloon which can be positioned across a particular stricture or narrowed region. For example, in percutaneous transluminal angioplasty (PTA), a catheter bearing a collapsed balloon is introduced into a patient's blood vessel and advanced until the balloon lies across a site to be dilated. The balloon of the catheter is then inflated with a fluid so as to widen the vessel or the like, without trauma to the vessel at the site of treatment.
It is sometimes necessary or desirable to provide the site of dilation with a device or structure which prevents subsequent stenosis (closure) of the site. Stents are a known class of surgical devices which are useful for maintaining open lumens. For example, U.S. Pat. No. 4,580,568 (C. Gianturco, Apr. 8, 1986), U.S. Pat. No. 4,739,762 (J.C. Palmaz, Apr. 26, 1988) and U.S. Pat. No. 4,907,336 (C. Gianturco, Mar. 13, 1990) all disclose stents having a cylindrical shape. Each of these stents is contained by a removable sheath so as to facilitate its introduction into a blood vessel or other body portion. (Stents embodying the invention disclosed in the first of these patents is sold under the name “Z-stent,” a trade name of Cook Incorporated.) In the use of each, the sheath is withdrawn after the stent is positioned at the desired site, and only after withdrawal of the sheath is the stent expanded by a balloon catheter ('762 and '336), or is the stent permitted to self-expand ('568). The expanded stent prevents subsequent stenosis of the site.
In the use of these and other stents, it is highly desirable to minimize the cross-sectional area (profile) of the collapsed stent, as well as that of the retractable sheath and of the catheter on which they are carried. Accordingly, the sheath must typically be made of a thin-walled material which contains the stent in close proximity to the balloon. The combination of these requirements often makes it difficult to retract such a sheath without stretching the sheath or displacing the stent on the balloon. Such a sheath can stretch so much as to fail to uncover the stent, rendering the system for deploying the stent useless. Furthermore, such a sheath can also displace the stent and prevent proper deployment. Moreover, the delivery of a stent to the site of dilation on the same balloon which dilates the site can be subject to other drawbacks. Most notably, friction between the containment sheath and the catheter or stent can make it very difficult to slide the sheath far enough to expose the stent for proper expansion. This drawback can be particularly acute with catheters and stents of small diameter.
U.S. Pat. No. 5,464,419 (H. Glastra, Nov. 7, 1995) discloses a PTA device which appears to lack any sheath at all for containing a stent. Rather, the device includes a spirally wound stent of specific construction which is held in an unexpanded configuration by biologically degradable, thin cords
12
. The cords
12
break during expansion of the stent, caused by inflation of a PTA balloon positioned within the spiral stent. The disclosed device can be subject to several drawbacks during use, however. The thin cords
12
are spaced apart, so that the balloon and stent would presumably experience uneven initial expansion in the spaces between the cords. Indeed, the spaced cords pose the potential risk of cutting, breaching or damaging the stent during expansion. Prior to deployment, the spaced cords can give the stent and balloon an irregular degree of stiffness along their length, making the device somewhat more likely to kink during the PTA procedure. Further, the cords can be difficult to affix to the stent, especially to stents of relatively small diameter, such as those intended for deployment in the vascular system.
U.S. Pat. No. 5,316,543 (M. A. Eberbach, May 31, 1994) discloses an apparatus useful in the laparoscopic treatment of hiatal hernias, which includes a rigid outer sleeve having longitudinal recesses and flanges for manual splitting of the sleeve. The patent appears to contain no disclosure or suggestion of the use of such a sleeve for containing a stent prior to deployment of the stent, nor any disclosure or suggestion of any way in which the sleeve could be modified to be used in conjunction with a stent. Moreover, the sleeve is disclosed as being rigid, while the sheaths employed for deploying stents (particularly stents to be positioned in the vascular system) must usually have good flexibility.
It would be highly desirable to have a device or method for deploying a stent which did not require retraction or withdrawal of a containment sheath prior to expansion of the stent. It would also be highly desirable to discover such a device or method which was relatively low cost, which was of relatively straight-forward construction, which possessed high reliability during use, which was easy to remove from the patient if complications arose prior to expansion of the stent, and which did not possess discrete threads which might otherwise damage the stent or catheter during use, or interfere with positioning of the stent.
SUMMARY OF THE INVENTION
The foregoing problems are solved and a technical advance is achieved in an illustrative stent deployment device having a catheter and a stent positioned on the catheter. Applicant has discovered that a splittable sleeve which is carried on the catheter, and which includes a portion extending over, more preferably fully over, and containing the stent, can successfully maintain the stent in a collapsed condition during its deployment at a desired location within a vessel or the like by the catheter, without requiring prior withdrawal or retraction of the sleeve. More particularly, Applicants have discovered that expansion of the collapsed stent can be performed by actuation of a mechanism for splitting at least the portion of the sleeve extending over the stent.
In regard to the present invention, “stent” is intended to have a broad meaning, and to include not only conventional stents, but also implants, prostheses and other devices which can be positioned within a human or veterinary patient by a catheter. “Sleeve” similarly is intended to have a broad meaning, and to include sheaths, tubes and catheters, as well as sleeves. “Split” is intended to include any way in which the sleeve is severed so as to permit expansion of the stent and removal of the sleeve from the patient, and therefore encompasses splitting, tearing, ripping, fracturing, breaking, bursting, separating and fissuring of the sleeve. Lastly, “fully” is intended to mean merely that the portion of the sleeve extending over the stent completely encircles the stent and covers at least a substantial portion of the stent (preferably, at least the majority of the stent) in a longitudinal direction.
Splitting of the portion of th
Bates Brian L.
Boatman Scott E.
DosPassos Susan
Fontaine Arthur B.
Hoffa Michael C.
Cook Incorporated
Godlewski Richard J.
Thaler Michael H.
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