Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent combined with surgical delivery system
Reexamination Certificate
1999-06-07
2001-11-13
Smith, Jeffrey A. (Department: 3732)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent combined with surgical delivery system
Reexamination Certificate
active
06315790
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not Applicable
BACKGROUND OF THE INVENTION
In typical PTCA procedures, a guiding catheter is percutaneously introduced into the cardiovascular system of a patient through a vessel and advanced through therein until the distal end thereof is at a desired location in the vasculature. A guidewire and a dilatation catheter having a balloon on the distal end thereof are introduced through the guiding catheter with the guidewire sliding through the dilatation catheter. The guidewire is first advanced out of the guiding catheter into the patient's coronary vasculature and the dilatation catheter is advanced over the previously advanced guidewire until the dilatation balloon is properly positioned across the lesion. Once in position across the lesion, the flexible, expandable, preformed balloon is inflated to a predetermined size with a liquid or gas at relatively high pressures, such as greater than about four atmospheres, to radially compress the artirosclerotic plaque of the lesion against the inside of the artery wall and thereby dilate the lumen of the artery. The balloon is then deflated to a small profile so that the dilatation catheter may be withdrawn from the patients vasculature and blood flow resumed through the dilated artery.
In angioplasty procedures of the kind described above, there may be injury to or restenosis of the artery, which either necessitates another angioplasty procedure, a surgical by-pass operation, or some method of repairing or strengthening the area. To strengthen the area and help prevent restenosis, a physician can implant an intravascular prosthesis for maintaining vascular patency, commonly called a stent, inside the artery at the lesion. The stent is expanded to a larger diameter for placement in the vasculature, often by the balloon portion of the catheter. Stents delivered to a restricted coronary artery, expanded to a larger diameter by a balloon catheter, and left in place in the artery at the site of a dilated lesion are shown in U.S. Pat. No. 4,740,207 to Kreamer and U.S. Pat. No. 5,007,926 to Derbyshire, the content of which is incorporated herein by reference. Palmaz et al., 156
Radiology
73 (1985) and U.S. Pat. No. 4,733,665 describe introduction of a stent over a balloon catheter (incorporated herein by reference).
To assist in accurate placement of the catheter and stent underneath the lesion site it is useful to visually monitor the catheter as it advances through a vessel. Fluoroscopes or other similar X-ray emitting devices are used to view the catheter within the body as it is advanced. However, in order for the catheter to be visible when exposed to X-rays, the catheter or a portion of the catheter, must be radiopaque to X-rays. In previous catheter designs, radiopaque marker bands or catheter tips are often attached to the catheter for this purpose.
An initial example of a catheter which utilizes an external metal radiopaque marker band is U.S. Pat. No. 5,759,174 to Fischell et al., the entire contents of which are hereby incorporated by reference, which has a single external metal marker band which is intended to identify the central portion of a stenosis once the delivery catheter is removed. Marker bands such as those disclosed by Fischell et al. are normally mounted externally on the delivery catheter and undesirably increase the profile of the catheter as well as its cost. Furthermore, marker bands are constructed from expensive and heavy radiopaque metals such as gold, platinum and tantalum or alloys of these dense materials. Marker bands constructed from these metals are also costly to manufacture.
Despite these shortcomings, marker bands are preferable over radiopaque tips alone, since a radiopaque catheter tip only provides for the end of the catheter to be visible as opposed to a desired area along the catheter shaft. For example, U.S. Pat. No. 5,429,597 to Demello et al., the entire contents of which are hereby incorporated by reference, discloses a balloon catheter having a radiopaque distal tip composed of a polymer mixed with a radiopaque powder such as tungsten. Such a tip is visible under X-ray observation. In addition Demello et al., discloses a preferred embodiment which uses of two metal radiopaque marker bands located along a core wire to better track the expandable region of a balloon.
U.S. Pat. No. 4,866,132 to Obligin et al.; U.S. Pat. No. 5,256,334 to Smid et al.; and U.S. Pat. No. 5,024,232 to Smid et al., the entire contents of each being hereby incorporated by reference, respectively disclose various methods of making radiopaque polymer complexes. The references also suggest using radiopaque polymer complexes with existing implantable devices which are presently used with radiolucent plastics. These references do not however, disclose the present catheter which is constructed with radiopaque polymer hubs as disclosed below, and where the hubs provide the dual function of stent crimping and marker bands.
BRIEF SUMMARY OF THE INVENTION
The present invention provides for a stent delivery system. The stent delivery system comprises, a balloon catheter having a proximal end and a distal end, the catheter having at least one radially mounted stent securement hub located near the distal end, the stent securement hub being made of a radiopaque polymer. The catheter includes a stent receiving portion adapted to receive a stent over the balloon and the radiopaque stent securement hub.
In the preferred embodiment of the invention the basic components of the stent delivery system consist of a catheter having a noncompressible inner shaft, an outer shaft, and two radiopaque stent mounting hubs coaxially arranged about the inner shaft. The two radiopaque hubs have a diameter greater than that of the inner shaft and rest underneath the stent and balloon, defining the stent mounting region. The hubs are spaced to match the length of the stent, thereby providing a visual guide for accurate placement and deployment when viewed with a fluoroscope or other x-ray emitting device. Alternatively, the portion of the inner shaft upon which the stent is mounted may be radiopaque.
The radiopaque quality of the hubs or shaft is provided for by constructing the hubs with a typical polymer material and adding a radiopaque substance from the group consisting of barium, bismuth, tungsten, gold, titanium, iridium, platinum or rhenium. In a preferred embodiment high density polyethylene is mixed with a predetermined amount of tungsten, such as 80% tungsten by weight.
Thus, an object of the present invention is to provide for a low profile stent delivery catheter which incorporates a relatively low cost radiopaque polymer material to define the stent mounting region, so that the stent mounting region may be visible when exposed to X-rays and be more accurately positioned within a bodily vessel as a result.
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patent: 6019778 (2000-02-01), Wilson
Gerberding Brent C.
Ren Brooke Qin
Robert Eduardo C.
Sci-Med Life Systems, Inc.
Smith Jeffrey A.
Vidas Arrett & Steinkraus P.A.
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