Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent combined with surgical delivery system
Reexamination Certificate
2000-05-19
2003-08-19
Milano, Michael J. (Department: 3731)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent combined with surgical delivery system
Reexamination Certificate
active
06607551
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to endoluminal grafts or “stents” and, more specifically, to stent delivery systems or “introducers”.
BACKGROUND OF THE INVENTION
A stent is an elongated device used to support an intraluminal wall. In the case of a stenosis, a stent provides an unobstructed conduit for blood in the area of the stenosis. Such a stent may also have a prosthetic graft layer of fabric or covering lining the inside and/or outside thereof. Such a covered stent is commonly referred to in the art as an intraluminal prosthesis, an endoluminal or endovascular graft (EVG), or a stent-graft. As used herein, however, the term “stent” is a shorthand reference referring to a covered or uncovered such stent.
A covered stent may be used, for example, to treat a vascular aneurysm by removing the pressure on a weakened part of an artery so as to reduce the risk of rupture. Typically, a stent is implanted in a blood vessel at the site of a stenosis or aneurysm endoluminally, i.e. by so-called “minimally invasive techniques” in which the stent, restrained in a radially compressed configuration by a sheath or catheter, is delivered by a stent deployment system or “introducer” to the site where it is required. The introducer may enter the body through the patient's skin, or by a “cut down” technique in which the entry blood vessel is exposed by minor surgical means. When the introducer has been threaded into the body lumen to the stent deployment location, the introducer is manipulated to cause the stent to be ejected from the surrounding sheath or catheter in which it is restrained (or alternatively the surrounding sheath or catheter is retracted from the stent), whereupon the stent expands to a predetermined diameter at the deployment location, and the introducer is withdrawn. Stent expansion may be effected by spring elasticity, balloon expansion, or by the self-expansion of a thermally or stress-induced return of a memory material to a pre-conditioned expanded configuration.
Referring now to a typical prior art stent introducer as seen in FIG.
1
A and
FIG. 1B
, there is shown a standard pre-loaded stent delivery system
10
comprising an outer sheath
12
, a compressed stent
14
loaded therein, and a conventional stabilizer
16
loaded adjacent to the proximal end
17
of the stent. As used herein, the term “proximal” refers to the end closer to an access location outside the body whereas “distal” refers to the farther from the access location. The term “stabilizer” is used in the art to describe component
16
of stent delivery systems used to stabilize or prevent retraction of stent
14
when sheath
12
is retracted, thus effecting deployment of the stent into a desired location by forcing relative movement between the sheath and the stent.
Delivery system
10
also may comprise a catheter tip
20
at its distal end attached to an internal sheath
23
that runs through the delivery system through inner lumen
22
in stabilizer
16
, as shown in
FIG. 1A. A
stabilizer handle
26
is typically located at the proximal end of stabilizer
16
, outside the body lumen. Internal sheath
23
may guide the delivery system through the body lumen over a guidewire (not shown) to the area to be repaired, or may be adapted for inflating a balloon (if applicable), and/or for flushing the system. The delivery system may additionally have radiopaque markers (not shown) at selected locations therein to be used for fluoroscopic guidance of the system through the body lumen.
To deploy stent
14
, delivery system
10
is threaded through the body lumen to a desired location for stent deployment. Outer sheath
12
is then retracted, and stabilizer
16
acts as a stabilizer to keep stent
14
from retracting with the sheath. As outer sheath
12
retracts, stent
14
is exposed and expands into place in the body lumen to be repaired.
Some stents have relatively low column strength either along their whole length or in discrete sections thereof. Their low column strength may be an inherent result of a flexible stent architecture. Such low-column-strength stents or stent sections are easily deformed in a longitudinal direction, and thus longitudinal force is not transmitted along the length of the stent. This inability to transmit longitudinal force may result in such stents collapsing in an accordion fashion as the sheath is retracted or as the stent is ejected by movement of the stabilizer, when the stent is deployed using a standard stabilizer positioned at the proximal end of the stent. This collapsing is caused primarily by frictional forces, such as frictional forces between the sheath and the stent (in the case where the stent is deployed by retraction of the sheath) or between the stent and the body lumen (in the case where the stent is deployed by ejection). Thus, a low column strength segment is one which tends to collapse due to frictional forces upon deployment of the stent by a conventional stabilizer positioned at the proximal end of the stent. This collapsing may cause damage to the stent or incorrect deployment. Thus, it is desirable to employ a stent-stabilizer combination that avoids such collapse.
U.S. Pat. No. 5,702,418 to Ravenscroft, of common assignment with the present invention, discloses an introducer comprising a stabilizer having an inner core that underlies a compressed stent within a sheath. The core has one or two proximal rings attached to and extending radially from the surface of the inner core for engaging the compressed stent at the proximal end thereof. Ravenscroft further describes but does not illustrate stabilizer embodiments having additional rings, rings including slots for receiving portions of the stent overlying the rings, and rings formed or defined by a plurality of protuberances or fingers extending from the core to engage and interlock the stent minimum inner diameter at the proximal end thereof. The purpose of these rings, according to Ravenscroft, is to allow selective retraction and deployment of the stent.
Thus, it is known to have rings or protuberances that engage the inner diameter of the stent, but only with respect to one or more rings that engage the proximal end of the stent to enable selective retraction and deployment of the stent. There remains a need, therefore, for a means to facilitate deployment of endoluminal stents with relatively low column strength.
SUMMARY OF THE INVENTION
In accordance with this invention, there is provided a stent delivery system for receiving, endoluminally transporting, and endoluminally deploying an elongated stent for holding open a body lumen, which system facilitates the use of stents with low column strength. The stent delivery system comprises a stent, an overlying sheath, and a stabilizer. The stent has an inner periphery that defines an interior space extending lengthwise along at least a part of the stent, at least one longitudinal segment of which may comprise relatively low column strength (or reduced column strength as compared to other parts of the stent), in that such segment is easily collapsed longitudinally. Such a low column strength segment may comprise all or nearly all the length of the stent. The stent is adapted to be radially compressed and loaded within the delivery system for introduction into the body lumen and expanded for deployment within the body lumen. The sheath overlies the compressed stent during introduction of the stent within the body lumen from a proximal access location to a distal deployment location. The stabilizer is disposed within the stent interior space and has at least one surface element adapted to engage the stent inner periphery in a region containing the low-column-strength segment.
The stent may comprise a plurality of peripheral members disposed in succession along the length of the stent (i.e. longitudinally), in which case the stabilizer comprises at least one surface element adapted to engage individual peripheral elements in a manner capable of imparting a longitudinal force thereto. The stabilizer may comprise a plurality of pr
Bettuchi Michael J.
DiMatteo Kristian J.
Golds Ellen
Keller John
Ketterer Matthew S.
Ho (Jackie ) Tan-Uyen T.
Milano Michael J.
Sci-Med Life Systems, Inc.
LandOfFree
Stent delivery system with nested stabilizer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Stent delivery system with nested stabilizer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stent delivery system with nested stabilizer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3088792