Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis
Reexamination Certificate
1997-10-27
2002-04-30
Dawson, Glenn K. (Department: 3761)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Reexamination Certificate
active
06380457
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to devices for deploying body implantable prostheses intended for fixation in body cavities, and more particularly to devices that utilize guidewires in the delivery and placement of stents.
Stents are employed in a variety of patient treatment and diagnostic procedures, for fixation in blood vessels, biliary ducts and other body lumens to maintain the passages. For example, a radially self-expanding stent can be deployed in an artery following a percutaneous transluminal coronary angioplasty (PTCA) procedure or a percutaneous transluminal angioplasty (PTA) procedure. The stent resists a tendency in the vessel to close, thus countering acute reclosure and plaque restenosis. A highly preferred construction for a radially self-expanding stent, disclosed in U.S. Pat. No. 4,655,771 (Wallsten) is a flexible tubular braided structure formed of helically wound thread elements. Wallsten teaches use of a catheter for delivering the stent to the fixation site. A pair of grips maintain the stent at the distal end of the catheter, and are controlled by an operational member at the proximal end of the catheter, to release the stent after positioning and initial medial expansion of the stent.
Another prosthesis construction is disclosed in U.S. Pat. No. 4,681,110 (Wiktor). A flexible tubular liner, constructed of braided strands of a flexible plastic, is delivered into the aorta by a main catheter tube, with the prosthesis carried at the distal end of the main tube. A secondary tube, inside the main catheter tubing and terminating just proximally of the liner, is held in place as the main tube is withdrawn. Thus the liner is deployed initially at its distal end, and radially self-expands against an aneurism to direct blood flow past the aneurism.
Yet another approach to deploying self-expanding stents is shown in U.S. Pat. No. 4,732,152 (Wallsten et al). Often referred to as the “rolling membrane” method, this approach involves a tube or membrane folded over upon itself to provide a double wall for maintaining a self-expanding stent at the distal end of a catheter. The outer wall of the membrane is movable proximally to expose the stent and allow radial self-expansion, beginning at the distal end of the stent.
Prostheses also have been constructed of plastically deformable materials, where upon a dilatation balloon or other means is required to radially expand the stent, e.g.. as shown in U.S. Pat. No. 4,733,665 (Palmaz). In Palmaz, a radially expandable vascular graft is delivered by a delivery catheter, with the graft surrounding a dilatation balloon of a balloon catheter. For deployment, the balloon catheter is expanded, thus to expand the graft.
Regardless of the type of prosthesis, its deployment frequently involves guiding the catheter or other delivery appliance through convoluted paths defined by arteries or other body passages. A well known technique for guiding the delivery catheter includes initially positioning a guidewire along the desired path, with the distal end of the guidewire near the treatment site and a proximal portion of the guidewire remaining outside of the body. The delivery catheter is formed with a lumen that runs the length of the catheter. When the proximal end portion of the previously positioned guidewire is threaded into the distal end of the delivery catheter, the delivery catheter can be advanced distally over the guidewire, ultimately to the treatment site for stent deployment.
Procedures that employ guidewires often require exchanging of treatment appliances. For example, a balloon catheter may be employed in a PTA or PTCA procedure, followed by placement of a stent or other prosthesis. This exchange or replacement of catheters requires that the proximal portion of the guidewire protruding from the patient's body be longer than the balloon catheter, the prosthesis delivery catheter, or any other catheter involved in the procedure. This creates difficulty in maneuvering the guidewire and catheters due to the catheter length dimensions involved, which can range from 30 to 300 centimeters. In addition to handling difficulties, the guidewire and catheter tubing generate a substantial frictional force, due to the length along which their respective exterior and interior surfaces interact.
Therefore, it is an object of the present invention to provide a device for delivering and deploying a body implantable prosthesis using a prepositioned guidewire that protrudes from the patient's body a distance substantially less than heretofore required.
Another object is to provide a prosthesis delivery device capable of utilizing a prepositioned guidewire without the need for a guidewire lumen running the entire length of the device.
A further object is to provide a prosthesis deployment device including an outer catheter and a coaxial inner catheter movable axially within the lumen of the outer catheter, in which the inner catheter includes a guidewire receiving lumen only along its distal portion, with a proximal termination open to the exterior of the inner catheter and alignable with an opening through the outer catheter, thus to facilitate passage of the guidewire from the innermost lumen to the exterior of the outer catheter.
Yet another object is to provide a prosthesis delivery device as part of a system of several devices alternatively advanced over a previously positioned guidewire, with exchanges of the devices being substantially simplified due to a shorter guidewire and reduced guidewire/device friction.
SUMMARY OF THE INVENTION
To achieve these and other objects, there is provided an apparatus for deploying a prosthesis at a treatment site within a body lumen. The apparatus includes an elongate prosthesis carrier having a proximal end region and a distal end region including a prosthesis support segment. The carrier has a carrier wall, and a guidewire lumen running axially of the carrier at least along the prosthesis support segment. A first opening is formed at the distal end of the support segment for admitting a guidewire into the guidewire lumen. A second opening through the carrier wall at the proximal end of the support segment provides egress of the guidewire out of the guidewire lumen, whereby the carrier contains the guidewire only along the prosthesis support segment. A prosthesis retaining means releasibly supports a prosthesis in a delivery state along the support segment of the carrier. When in the delivery state, the prosthesis has a reduced radius along its axial length to facilitate delivery of the prosthesis to a treatment site in a body lumen. A control means, operably associated with the retaining means, causes the retaining means to release the prosthesis when the support segment is positioned near the treatment site, thus to facilitate deployment of the prosthesis in a radially expanded state at the treatment site.
One preferred retaining means is a flexible, elongate outer catheter having a catheter lumen for containing the carrier. The outer catheter and carrier are movable relative to each other toward and away from a delivery configuration in which the outer catheter surrounds and radially compresses the prosthesis. Withdrawal of the outer catheter, i.e., proximal movement relative to the carrier, frees the prosthesis for radial expansion. The outer catheter advantageously has a slit running axially from a point near the proximal end of the support segment when the catheter and carrier are in the delivery configuration, to a proximal end region of the outer catheter. This allows the portion of the guidewire proximal to the guidewire lumen to be alternatively positioned within or outside of the outer catheter, as desired.
As compared to a conventional delivery apparatus that receives a guidewire along its entire length, the device of the present invention is substantially easier to manipulate. The proximal or exchange portion of the guidewire that protrudes from a patient's body need not be longer than the entire device, but merely longer than the distal end r
Healy Steven J.
Yurek Matthew T.
Boston Scientific Scimed Inc.
Dawson Glenn K.
Larkin Hoffman Daly & Lindgren Ltd.
Niebubr, Esq. Frederick W.
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