U.S. patent application number 10/416926 was filed with the patent office on 2004-05-20 for endovascular prosthesis.
Invention is credited to Erbel, Raimund, Penn, Ian M, Ricci, Donald R, Shukov, George A.
Application Number | 20040098091 10/416926 |
Document ID | / |
Family ID | 43757851 |
Filed Date | 2004-05-20 |
United States Patent
Application |
20040098091 |
Kind Code |
A1 |
Erbel, Raimund ; et
al. |
May 20, 2004 |
Endovascular prosthesis
Abstract
A endovascular prosthesis for implantation in a body passageway.
The prosthesis comprises a tubular wall which is: (i) movable
between a first longitudinal length and a second longitudinally
length, and (ii) radially expandible for implantation of the
prosthesis in the body passageway. In one embodiment, the tubular
wall has a longitudinally length which is variable by an
"accordian"-like action. In another embodiment, the tubular wall
has a longitudinally length which is variable by an
"telescoping"-like action. The longitudinal length of the tubular
wall may be varied in vivo to optimize deployment of the
endovascular prosthesis.
Inventors: |
Erbel, Raimund; (Essen,
DE) ; Ricci, Donald R; (Vancouver, CA) ; Penn,
Ian M; (Vancouver, CA) ; Shukov, George A;
(Los Altos, CA) |
Correspondence
Address: |
PATENT ADMINSTRATOR
KATTEN MUCHIN ZAVIS ROSENMAN
525 WEST MONROE STREET
SUITE 1600
CHICAGO
IL
60661-3693
US
|
Family ID: |
43757851 |
Appl. No.: |
10/416926 |
Filed: |
December 23, 2003 |
PCT Filed: |
November 19, 2001 |
PCT NO: |
PCT/CA01/01588 |
Current U.S.
Class: |
623/1.13 ;
623/1.15; 623/1.39 |
Current CPC
Class: |
A61F 2/958 20130101;
A61F 2/86 20130101; A61F 2250/0024 20130101; A61F 2250/0007
20130101; A61F 2002/075 20130101; A61F 2/88 20130101 |
Class at
Publication: |
623/001.13 ;
623/001.15; 623/001.39 |
International
Class: |
A61F 002/06 |
Claims
What is claimed is:
1. An endovascular prosthesis for implantation in a body
passageway, the prosthesis comprising a tubular wall, the tubular
wall being: (i) movable between a first longitudinal length and a
second longitudinally length, and (ii) radially expandible for
implantation of the prosthesis in the body passageway.
2. The endovascular prosthesis defined in claim 1, wherein the
tubular wall comprises a first tubular wall and a second tubular
wall in sliding engagement with one another.
3. The endovascular prosthesis defined in claim 2, wherein the
tubular wall comprises an annular portion for occlusion of a
section of the body passageway, the annular portion comprising a
first porous section and a non-porous section.
4. The endovascular prosthesis defined in claim 3, wherein the
tubular wall comprises a second porous section adjacent the annular
portion.
5. The endovascular prosthesis defined in claim 3, wherein the
tubular wall comprises a third porous section adjacent the annular
portion.
6. The endovascular prosthesis defined in any one of claims 2-3,
wherein the tubular wall comprises a second porous section disposed
adjacent one side of the annular portion and a third porous section
adjacent an opposed side of the annular portion.
7. The endovascular prosthesis defined in claim 6, wherein second
porous section and the third portion section are interconnected by
the first porous section.
8. The endovascular prosthesis defined in any one of claims 3-7,
wherein the non-porous section radially spans from about 90.degree.
to about 270.degree. of the annular portion.
9. The endovascular prosthesis defined in an), one of claims 3-7,
wherein the non-porous section radially spans from about
150.degree. to about 250.degree. of the annular portion.
10. The endovascular prosthesis defined in any one of claims 3-7,
wherein the non-porous section radially spans from about
180.degree. to about 240.degree. of the annular portion.
11. The endovascular prosthesis defined in any one of claims 3-10,
wherein the non-porous section extends longitudinally a distance in
the range of from about 2 cm about 10 cm.
12. The endovascular prosthesis defined in any one of claims 3-10,
wherein the non-porous section extends longitudinally a distance in
the range of from about 3 cm about 8 cm.
13. The endovascular prosthesis defined in any one of claims 3-10,
wherein the non-porous section extends longitudinally a distance in
the range of from about 3 cm about 6 cm.
14. The endovascular prosthesis defined in any one of claims 3-13,
wherein the non-porous section comprises a cover material disposed
over a fourth porous section.
15. The endovascular prosthesis defined in any one of claims 3-14,
wherein the non-porous section comprises a cover material disposed
connected to the first porous section.
16. The endovascular prosthesis defined ill claim 15, wherein the
cover material comprises a layer of polymer material.
17. The endovascular prosthesis defined in claim 1, wherein the
tubular wall comprises a plurality of interconnected expandable
annular members.
18. The endovascular prosthesis defined in claim 17, wherein the
annular members are interconnected by a plurality of longitudinal
members.
19. The endovascular prosthesis defined in claim 17, wherein the
annular members are interconnected by a cover material.
20. The endovascular prosthesis defined in any one of claims 1-19,
wherein the tubular wall comprises at least one radioopaque
marker.
21. The endovascular prosthesis defined in any one of claims 1-19,
wherein the tubular wall comprises a pair of radioopaque markers
disposed at opposed ends of the tubular wall.
22. The endovascular prosthesis defined in any one of claims 1-19,
wherein the tubular wall comprises a pair of radioopaque markers
disposed at opposed ends of the non-porous section.
23. The endovascular prosthesis defined in any one of claims 1-22,
wherein the tubular wall is constructed from a plastically
deformable material.
24. The endovascular prosthesis defined in claim 23, wherein the
plastically deformable material comprises stainless steel.
25. The endovascular prosthesis defined in claim 23, wherein the
plastically deformable material comprises a laminar structure.
26. The endovascular prosthesis defined in claim 25, wherein the
laminar structure comprises a layer of plastically deformable,
material and a layer of radioopaque material.
27. The endovascular prosthesis defined in any one of claims 1-22,
wherein the tubular wall is constructed from a self-expanding
material.
28. The endovascular prosthesis defined in claim 27, wherein the
self-expanding material comprises a shape memory alloy.
29. A method for endovascular blocking of an endovascular disease
condition located between a first location point and a second
location point in a target body passageway of a patient with the
endovascular prosthesis defined in any one of claims 1-28, the
method comprising the steps of: inserting the prosthesis and a
catheter within a body passageway by catheterization of the body
passageway; translating the prosthesis and catheter to a target
body passageway in which the endovascular disease condition is
located; positioning the distal end of the prosthesis such the
distal end of the prosthesis is substantially aligned with the
first location point; extending the distal end of the prosthesis
with respect to the catheter; exerting a radially outward expansive
force on the distal end of the tubular wall such that the distal
end of the tubular wall is urged against the target body
passageway; fixing a proximal portion of the prosthesis with
respect to the catheter; retracting the catheter thereby
longitudinally extending the expansible portion of the tubular wall
until the proximal end of the prosthesis is substantially is
substantially aligned with the second location point; freeing the
prosthesis with respect to the catheter; retracting the catheter to
expose the proximal end of the endovascular prosthesis; and
exerting a radially outward expansive force on the proximal end of
the tubular wall such that the proximal end of the tubular wall is
urged against the target body passageway.
30. The method defined in claim 29, wherein aortic disease
condition comprises aortic dissection.
31. The method defined in claim 29, wherein aortic disease
condition comprises blunt chest trauma.
32. The method defined in claim 29, wherein aortic disease
condition comprises aortic sclerosis.
Description
TECHNICAL FIELD
[0001] In one of its aspects, the present invention relates to an
endovascular prosthesis. In another of its aspects, the present
invention relates to a method of treating an aortic disease
condition in a patient.
BACKGROUND ART
[0002] Stents are generally known. Indeed, the term "stent" has
been used interchangeably with terms such as "intraluminal vascular
graft" and "expandable prosthesis". As used throughout this
specification the term "stent" is intended to have a broad meaning
and encompasses any expandable prosthetic device for implantation
in a body passageway (e.g., a lumen or artery).
[0003] In the past ten years, the use of stents has attracted an
increasing amount of attention due the potential of these devices
to be used in certain cases, as an alternative to surgery.
Generally, a stent is used to obtain and maintain the patency of
the body passageway while maintaining the integrity of the
passageway. As used in this specification, the term "body
passageway" is intended to have a broad meaning and encompasses any
duct (e.g., natural or iatrogenic) within the human body and can
include a member selected from the group comprising: blood vessels,
respiratory ducts, gastrointestinal ducts and the like.
[0004] Stent development has evolved to the point where the vast
majority of currently available stents rely on controlled plastic
deformation of the entire structure of the stent at the target body
passageway so that only sufficient force to maintain the patency of
the body passageway is applied during expansion of the stent.
[0005] Generally, in many of these systems, a stent, in association
with a balloon, is delivered to the target area of the body
passageway by a catheter system. Once the stent has been properly
located (for example, for intravascular implantation the target
area of the vessel can be filled with a contrast medium to
facilitate visualization during fluoroscopy), the balloon is
expanded thereby plastically deforming the entire stricture of the
stent so that the latter is urged in place against the body
passageway. As indicated above, the amount of force applied is at
least that necessary to expand the stent (i.e. the applied the
force exceeds the minimum force above which the stent material will
undergo plastic deformation) while maintaining the patency of the
body passageway. At this point, the balloon is deflated and
withdrawn within the catheter, and is subsequently removed.
Ideally, the stent will remain in place and maintain the target
area of the body passageway substantially free of blockage (or
narrowing).
[0006] See, for example, any of the following patents:
[0007] U.S. Pat. No. 4,733,665 (Palmaz),
[0008] U.S. Pat. No. 4,739,762 (Palmaz),
[0009] U.S. Pat. No. 4,800,882 (Gianturco),
[0010] U.S. Pat. No. 4,907,336 (Gianturco),
[0011] U.S. Pat. No. 5,035,706 (Gianturco et al.),
[0012] U.S. Pat. No. 5,037,392 (Hillstead),
[0013] U.S. Pat. No. 5,041,126 (Gianturco),
[0014] U.S. Pat. No. 5,102,417 (Palmaz),
[0015] U.S. Pat. No. 5,147,385 (Beck et al.),
[0016] U.S. Pat. No. 5,282,824 (Gianturco),
[0017] U.S. Pat. No. 5,316,023 (Palmaz et al.),
[0018] U.S. Pat. No. 5,755,771 (Penn et al.),
[0019] U.S. Pat. No. 5,906,640 (Penn et al.),
[0020] U.S. Pat. No. 6,217,608 (Penn et al.),
[0021] Canadian patent 1,239,755 (Wallsten), and
[0022] Canadian patent 1,245,527 (Gianturco et al.),
[0023] for a discussion on previous stent designs and deployment
systems.
[0024] To date, most stent development has focused on the so-called
coronary stents. While a number of advances in art of coronary
stent development have been made, there is room for
improvement.
[0025] One area which has received little or no attention is the
area of endovascular treatment of aortic disease. At this point it
is useful to review diseases of the aorta.
[0026] Aortic diseases contribute to the high overall
cardiovascular mortality. Relatively new imaging modalities (e.g.,
transesophageal echocardiography, magnetic resonance tomography,
helical computed tomography, electron beam computed tomography)
have been introduced during the last decade. These new imaging
techniques facilitate better and/or earlier diagnosis of aortic
diseases, even in emergency situations. These new imaging
techniques have had an effect on patient management during recent
years allowing more rapid diagnosis and decision making.
[0027] Generally, aortic disease is caused by mechanisms which
weaken the strength of the aortic wall, particularly, the aortic
media. Such wall weakening leads to higher wall stress, which can
induce aortic dilatation and aneurysm formation, eventually
resulting in aortic dissection or rupture. The various categories
of aortic disease are summarized in FIG. 1.
[0028] Diseases of the aorta are a significant problem in medicine.
There are two general approaches: drug treatment and surgery. Drug
treatment is used to lower blood pressure--this approach is
disadvantageous since, at best, it modulates the effect of the
disease while still leaving the patient at significant risk.
Surgery is disadvantageous due to the high mortality and morbidity,
even in centers of excellence. The increasing age of the population
is resulting in an increased incidence of aortic disease as it is a
degenerative disease. Further, aortic stiffness increases with age
thereby reducing coronary and other artery perfusion.
[0029] There are three (3) indications of aortic disease which are
regularly of clinical interest: (1) aortic dissection, (2) blunt
chest trauma (with consequential trauma to the aorta), and (3)
aortic sclerosis.
[0030] Aortic dissection is known to occur in approximately 15-20
cases/1 million inhabitants/year with a mortality of 50% in the
first year and 5% per hour for the first 5 hours after the onset of
symptoms. It results in a splitting of the aortic wall, a bleeding
into the wall with formation of a true and false (new) lumen
separated by a flap called "intima" with tear or "rupture point".
In patients with involvement of the ascending aorta, surgery is
performed and drug treatment preferred in patients with involvement
of the descending aorta. As stated above, despite surgeries
mortality is still high. The main problem is the organ perfusion of
the abdomen which results in shock and multiorgan failure.
Relatively recent studies have demonstrated that intramural
hemorrhage, intramural hematoma and aortic ulcer may be signs of
evolving dissections or dissection subtypes. Currently, the various
forms of dissection may be classified as follows:
[0031] Class 1 (FIG. 2a): Classical aortic dissection with an
intimal flap between true and false lumen;
[0032] Class 2 (FIG. 2b): Medial disruption with formation of
intramural hematoma/hemorrhage;
[0033] Class 3 (FIG. 2c): Discrete/subtle dissection without
hematoma, eccentric bulge at tear site;
[0034] Class 4 (FIG. 2d): Plaque rupture leading to aortic
ulceration, penetrating aortic atherosclerotic ulcer with
surrounding hematoma, usually subadventitial; and
[0035] Class 5 (FIG. 2e): Iatrogenic and traumatic dissection.
[0036] Each of these classes of dissection can be seen in their
acute and chronic stages; chronic dissections are considered to be
present if more than 14 days have elapsed since the acute
event.
[0037] Classic Aortic Dissection (Class 1--FIG. 2a)
[0038] Acute aortic dissection is characterized by the rapid
development of an intimal flap separating a true lumen and false
lumen. Due to the pressure difference the true lumen is usually
smaller than the false lumen. Intimal flap tears characterize
communicating dissections. However, tears are not always found and
non-communicating dissections are not uncommon. The dissection can
spread from diseased segments of the aortic wall in an antegrate or
retrograde fashion, involving side branches and causing other
complications.
[0039] Intramural Hematoma/Hemorrhage (Class 2--FIG. 2b)
[0040] An intramural hematoma is believed to be the initial lesion
in the majority of cases of cystic medial degeneration leading to
aortic dissection in which the intimal tear seems to be secondary
to preceding intramural dissection. Intramural hematoma may be the
result of ruptured normal-appearing vasa vasorum which are not
supported by the surrounding aortic media or the result of rupture
of diseased vasa vasorum. As a dissecting hematoma extends along
the aorta the weakened inner wall is subjected to the elongating
force of the diastolic recoil. Differences in elasticity between
the aortic fibrous adventitia and the inner more elastic media may
play an additional role.
[0041] In autopsy studies, dissecting aneurysms without tears have
been found in up to 12% of 311 autopsies. Others studies have
reported an incidence of 4% in 505 cases. In a series of sudden
deaths, 67% of patients with dissections did not have tears. The
incidence of intramural hemorrhage and hematoma in patients with
suspected aortic dissection, as observed by various new imaging
techniques, seems to be in the range of 10-30%.
[0042] There are two distinct types of intramural hematoma and
hemorrhage.
[0043] Type I intramural hematoma and hemorrhage shows a smooth
inner aortic lumen, the diameter is usually less than 3.5 cm, and
the wall thickness greater than 0.5 cm. Echo free spaces (seen
echocardiographically) as a sign of intramural hematoma are found
in only .quadrature. of the patients. The mean longitudinal extent
of the hematoma is about 11 cm and the echo free spaces show
minimal or no signs of flow.
[0044] Type 11 intramural hematoma and hemorrhage occurs in aortic
arteriosclerosis. A rough inner aortic surface with severe aortic
sclerosis is characteristic, the aorta is dilated to more than 3.5
cm and calcium deposits are frequently found. Mean wall thickness
is 1.3 cm with a range of from about 0.6 to about 4 cm, and echo
free spaces are found in 70.degree. of the patients studied. The
longitudinal extension has a similar range as in Type I hematoma,
usually about 11 cm. Intramural hemorrhages are more often found in
the descending than in the ascending aorta.
[0045] The fact that intramural hemorrhage and hematoma can lead to
aortic dissection has only be demonstrated in follow-up studies.
Acute aortic dissection as a consequence of intramural hemorrhage
and hematoma develops in from about 28% to about 47% of the
patients. It is associated with aortic rupture in from about 21% to
about 47%; and regression is seen in about 10% of the patients.
[0046] Subtle-Discrete Aortic Dissection (Class 3--FIG. 2c)
[0047] The structural weakness can either lead to clinically
undetected disease or minor forms of aortic dissection. Subtle
dissection has been described as a partial stellate or linear tear
of the vessel wall, covered by thrombus. After the partial tear
forms a scar, this constellation is called abortive, discrete
dissection. Partial ruptures of the inner layer of the aorta allow
the blood to enter the already damaged media and thus cause
dissection of the aortic wall, eventually leading to a second lumen
within the wall, to a rupture or healing during follow-up.
[0048] Plague Rupture/Ulceration (Class 4--FIG. 2d)
[0049] Ulceration of atherosclerotic aortic plaques can lead to
aortic dissection or aortic perforation. This was first observed by
computed tomography. Innovations in imaging techniques (e.g.,
intravascular ultrasound, spiral computed tomography and magnetic
resonance imaging) provide new insight. The ability to diagnose
aortic ulceration has thereby been improved and further affect the
descending thoracic aorta, as well as the abdominal aorta, and are
usually not associated with an extensive longitudinal propagation
or branch vessel compromise. Valvular, pericardial or other
vascular complications seem to be rare. The ulcer may penetrate
beyond the internal border, often with an nipple-like projection
with subjacent Type II intramural hematoma formation. The
continuous erosion of the atherosclerotic plaque may eventually
violate the internal elastic membrane. False aneurysms, aortic
rupture or dissections may occur.
[0050] Aortic sclerosis is normally divided into four grades from
thickening of the intima (Grade I) up to the development of free
floating thrombi (Grade IV) with the danger of embolism. In elderly
patients, the incidence of the Grade IV aortic sclerosis is
increasing. This has lead to a significant occurrence of stroke in
patients. Thus, if a treatment of aortic sclerosis Grade IV with
thrombi free floating in the aortic lumen could be developed, this
would likely obviate or mitigate the consequential occurrence of
stroke.
[0051] Currently, there is no reliable treatment approach for
aortic sclerosis particularly the Grade IV type. Anticoagulation is
a known approach, however this treatment must be accepted with the
danger of hemorrhagic strokes, particularly in the older patients
Further, the therapy is very difficult to monitor. Surgery is very
complicated and has a high mortality and morbidity. Currently,
surgery is not seen as a desirable alternative to anticoagulation
therapy.
[0052] Traumatic/Iatrogenic Aortic Dissection (Class 5--FIG.
2e)
[0053] Blunt chest trauma usually causes dissection of the
ascending aorta and/or the region of the ligamentum Botalli at the
aortic isthmus. Iatrogenic dissection of the aorta may rarely occur
during heart catheterization. It is regularly seen following
angioplasty of an aortic coarctation, but can also be observed
after cross clamping of the aorta and after the use of intraaortic
balloon pumping. Most catheter-induced dissections are retrograde
dissections. They will usually decrease in size as the false lumen
thromboses. Proximal progression of the coronary dissection into
the aortic root may be observed. In blunt chest trauma, the large
acceleration of the aorta is leading to an intimal, medial or
transsection of the aorta particularly at the adjunction at the
aortic arch and the descending aorta (15-20% of blunt chest trauma
cases are related to aortic injury). As a consequence of this blunt
chest trauma, mediastinal hematoma can occur with abrupt death of
the patient. The blunt chest trauma is known to occur in accidents
involving heavy motorcycles and cars, as well as in other chest
traumas. The diagnosis is verge difficult but has been improved by
transesophageal echocardiography. Typically, the damage to the
aorta is limited to a small portion comprising 3 cm -5 cm of the
aorta. Conventionally, surgery was the only treatment to stabilize
these patients. A mortality rate of 90% has been seen if surgery
was not timely preformed. Even if surgery was timely performed,
there is a significant mortality rate.
[0054] Most prior art attempts to improve surgical techniques to
treat aortic dissection have not be particularly successful.
[0055] It is also worth pointing out that the so-call "stent
grafts" are not well suited for treating diseases of the aorta.
Specifically, a conventional stent graft is generally of a fixed
longitudinal length. Since the anatomy of each patient is different
and the overall longitudinal length of the aortic or other
endoluminal disease condition is variable, the stent graft should
be of a specific or customized longitudinal length so as to
minimize the occurrence side branch blockage. This is inconvenient
and requires inventory stocking of a number of stent grafts having
a variety of different longitudinal lengths to have devices on hand
for use in most situations.
[0056] Thus, despite the advances made in the art, there is still a
need for an endovascular prosthesis capable obviates or mitigates
at least one of the above-mentioned disadvantages of the prior art.
Specifically it would be desirable to have an endovascular
prosthesis whose longitudinal length could be adjusted in vivo by
the physician during implanted of the prosthesis.
DISCLOSURE OF THE INDENTION
[0057] It is an object of the present invention to provide a novel
endovascular prosthesis which obviates or mitigates at least one of
the above-mentioned disadvantages of the prior art.
[0058] Accordingly, in one of its aspects, the present invention
provides an endovascular prosthesis for implantation in a body
passageway, the prosthesis comprising a tubular wall, the tubular
wall being: (i) movable between a first longitudinal length and a
second longitudinally length, and (ii) radially expandible for
implantation of the prosthesis in the body passageway.
[0059] In another of its aspects, the present invention provides an
endovascular prosthesis for implantation in a boded passageway, the
prosthesis comprising a first tubular wall and a second tubular
wall in longitudinal sliding engagement with one another, the first
tubular wall and the second tubular wall being radially expandible
for implantation of the prosthesis in the body passageway.
[0060] In another of its aspects, the present invention provides a
method for endovascular blocking of an endovascular disease
condition located between a first location point and a second
location point in a target body passageway of a patient with an
endovascular prosthesis comprising a first tubular wall and a
second tubular wall in longitudinal sliding engagement with one
another the first tubular wall and the second tubular wall being
radially expandible, the method comprising the steps of:
[0061] inserting the prosthesis and a catheter within a body
passageway by catheterization of the body passageway;
[0062] translating the prosthesis and catheter to a target body
passageway in which the endovascular disease condition is
located;
[0063] positioning the distal end of the prosthesis such the distal
end of the prosthesis is substantially aligned with the first
location point;
[0064] extending the distal end of the prosthesis with respect to
the catheter;
[0065] exerting a radially outward expansive force on the distal
end of the tubular wall such that the distal end of the tubular
wall is urged against the target body passageway;
[0066] fixing a proximal portion of the prosthesis with respect to
the catheter;
[0067] retracting the catheter thereby longitudinally extending the
expansible portion of the tubular wall until the proximal end of
the prosthesis is substantially is substantially aligned with the
second location point;
[0068] freeing the prosthesis with respect to the catheter;
[0069] retracting the catheter to expose the proximal end of the
endovascular prosthesis; and
[0070] exerting a radially outward expansive force on the proximal
end of the tubular wall such that the proximal end of the tubular
wall is urged against the target body passageway.
[0071] In yet another of its aspects, the present invention
provides a method for endovascular blocking of an endovascular
disease condition located between a first location point and a
second location point in a body passageway of a patient with
endovascular prosthesis comprising a tubular wall comprising a
distal end and a proximal end, the tubular wall being: (i) movable
between a first longitudinal length and a second longitudinally
length, and (ii) radially expandible for implantation of the
prosthesis in the body passageway, the method comprising the steps
of:
[0072] disposing the prosthesis in a catheter;
[0073] inserting the prosthesis and catheter within a body
passageway by catheterization of the body passageway;
[0074] translating the prosthesis and catheter to a target body
passageway in which the endovascular disease condition is
located;
[0075] extending the distal end of the prosthesis from the
catheter,
[0076] positioning the distal end of the prosthesis such the distal
end of the prosthesis is substantially aligned with the first
location point;
[0077] exerting a radially outward expansive force on the distal
end of the tubular wall such that the distal end of the tubular
wall is urged against the target body passageway;
[0078] urging the proximal end of the prosthesis against the
catheter;
[0079] retracting the catheter thereby longitudinally extending the
expansible portion of the tubular wall until the proximal end of
the prosthesis is substantially is substantially aligned with the
second location point;
[0080] freeing the proximal end of the prosthesis with respect to
the catheter;
[0081] retracting the catheter to expose the proximal end of the
endovascular prosthesis; and
[0082] exerting a radially outboard expansive force oil the
proximal end of the tubular wall such that the proximal end of the
tubular wall is urged against the target body passageway.
[0083] Generally, the present prosthesis can be advantageously used
to treat the indications of aortic disease referred to hereinabove.
Specifically, as will be described in more detail hereinbelow, the
present endovascular prosthesis has a longitudinal length which may
be varied in vivo to optimize the length there while obviating or
mitigated side branch occlusion.
[0084] Thus, the preferred form of the present endovascular
prosthesis device is a stent system which comprises a
longitudinally expansible or variable portion. Preferably, the
longitudinally expansible or variable portion is at least partially
radially, covered by a non-porous or graft material.
[0085] With reference to aortic dissection, the present prosthesis
normally will be implanted at the side of the intima tear in order
to block the flow from the true lumen into the false lumen at the
dissection connection. The present prosthesis may be advantageously
used in optimizing the length of the prosthesis in treating
dissection of the descending part of the aorta.
[0086] A preferred feature of the present endovascular prosthesis
is that it has only a partial, radial non-porous or graft covering.
Placement and positioning of the device can be facilitated by
intravascular ultrasound and transesophageal echocardiography
blocking the tear and while obviating or mitigating covering the
entire aortic wall--e.g., the portion of the aortic wall possibly
containing important side branches.
[0087] Once implanted, an advantage of the preferred form of the
present endovascular prosthesis is that it allows flow from the
proximal to the distal aorta even during the implantation of the
device due to the unique design. In contrast, conventional stent
grafts must be used with the concurrent danger of abrupt rise of
blood pressure leading to an extension and enlargement of the
dissection.
[0088] The present endovascular prosthesis may be used
advantageously to block the tear, thereby obviating or mitigating
flow from the true lumen to the false lumen. Thus, the healing
process begins which, in the successful cases, will lead during
follow-up within 6 months to total obliteration of the false lumen
and strengthening of the aortic wall. In addition the pressure in
the false lumen is reduced or eliminated and thereby, the true
luman can expand and improve the organ perfusion.
[0089] When properly deployed, the present endovascular prosthesis
will protect the diseased pant of the aorta, so that little or no
blood is escapes from the lumen to the mediastinum and thereby, the
patient is stabilized. Using intravascular ultrasound and
transesophageal echocardiography., the present endovascular
prosthesis may be appropriately navigated to block the damage of
the aorta. Again as in treatment of aortic dissection, it is
important to avoid blockage of multiple arteries which are
supplying the back bone since this can lead to paraplegia with
enormous consequences for the patient.
[0090] Indeed, to the knowledge of the present inventors, the
present endovascular device is the first such device to be useful
in reliable treatment of aortic diseases. Thus, with the present
endovascular device, blockage of the aortic flow is obviated or
mitigated and abrupt blood pressure increases (which could lead to
a fatal event) are avoided. Further, since the present device may
be deployed endovascularly (i.e. non-surgically), it is generally
safer for the patient and is less of a burden on public health
systems.
[0091] The present endovascular prosthesis may be used
advantageously to wrap the intimal flaps and thrombi to the aortic
wall and thereby obviate or mitigate the danger of stroke and
emboli without the need for anticoagulation. As the preferred form
of the present prosthesis covers only a radial portion of the
aortic circumference, blocking of side arteries, which are
supplying the back bone, is obviated or mitigated. As the preferred
form of the present prosthesis is open and not blocking the flow
from the proximal and distal aorta during the implantation, a blood
pressure increase is obviated or mitigated. Thus, a unique
advantage of the present prosthesis is that it can be used even in
multiple places of the aorta when more parts of the aorta are
showing thrombus formation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0092] Embodiments of the present invention will be described with
reference to the accompanying drawings, in which:
[0093] FIG. 1 illustrates a summary of the various categories of
aortic disease;
[0094] FIGS. 2a-2e illustrate various categories of dissection of
the aorta;
[0095] FIGS. 3a-3b illustrates a perspective view of an expandable
prosthesis in accordance with the present invention in its
retracted and extended position;
[0096] FIGS. 4a-4b illustrates a perspective view of an alternate
embodiment of the present endovascular prosthesis in the retracted
and extended position;
[0097] FIGS. 5-15 illustrate a sectional view of deployment of an
embodiment of the present endovascular prosthesis in a lumen;
[0098] FIG. 16 illustrates a perspective view of a perfusion
balloon useful in the embodiment illustrated in FIGS. 5-16;
[0099] FIG. 17 is a sectional view taken along line XVI-XVI in FIG.
16, as used in a body passageway;
[0100] FIGS. 18-24 illustrate a sectional view of deployment of an
alternate embodiment of a present endovascular prosthesis; and
[0101] FIG. 25 illustrates a perspective view the endovascular
prosthesis of FIGS. 18-24 after deployment.
BEST MODE FOR CARRYRNG OUT THE INVENTION
[0102] Thus, with reference to FIG. 3, there is illustrated an
expandable prosthesis 10 which comprises a plurality of annular
members 12 which are joined to one another by one or more
longitudinal spines 14. Annular members 12 are radially expandable.
Further, spine 14 is longitudinally expandable.
[0103] Disposed over a portion of expandable prosthesis 10 is a
cover material 16. Cover material 16 is adhered to various of
annular members 12.
[0104] In the longitudinally retracted version of endovascular
prosthesis 10 (i.e. FIG. 3a), the longitudinal length of cover
material 16 is greater than the longitudinal length A of
endovascular prosthesis 10 over which it is disposed. This can be
achieved by a suitable means such as folding of cover material 10
and the like. Alternatively, cover materials 16 can be made of a
material which can stretch.
[0105] As shown in FIG. 3b, it is possible to lengthen endovascular
prosthesis 10 prior to radio expansion thereof. The manner by which
this is achieved will be described hereinbelow. The point is, as
the spacing between adjacent annular members 12 is increased, cover
material 16 unfolds or otherwise lengthens (e.g., by stretching) to
allow the longitudinal length B of cover material 16 to increase
compared to length A in FIG. 3a.
[0106] An alternate embodiment is illustrated in FIG. 4.
Specifically, there is illustrated an endovascular prosthesis 10a
comprising a first section 11 and a second section 13. Sections 11
and 13 are longitudinally movable with respect to each other (e.g.,
in a telescoping manner). Each of sections 11 and 13 are similarly
constructed in that each comprises a series of annular members 12a
which are interconnected by a longitudinal spine 14a.
[0107] In the embodiment illustrated in FIG. 4, lengthening of
endovascular prosthesis 10a is achieved by relative of extension of
section 11 with respect to section 13. This enlarges the overall
length of cover material 16a which is disposed on each of sections
11 and 13.
[0108] As will be appreciated by those of skill in the art, the
combination of annular members 12 and 14 (FIG. 3) and sections 11
and 13 (FIG. 4) may be any conventional stent design which is
preferably optimized to facilitate navigation of the prosthesis to
the target site in the anatomy. The preferred design for the stent
sections is that disclosed in the Penn et al. International patent
applications referred to above. Of course, those of skill in the
art will recognize that the present endovascular prosthesis is not
restricted to the use of the specific stent designs illustrated in
FIGS. 3 and 4, and that any generally skill stent design may be
used.
[0109] Preferably, cover material 16 (FIG. 3) and 16a (FIG. 4) is a
sheet material such as Dacron.TM., Gortex.TM., other polymeric
materials, bovine pericardium and the like. The nature of the
material used for this purpose is not particularly restricted. It
is preferred that the material be substantially impermeable to
bodily fluids, that it is generally biocompatible and that the
physical nature thereof does not impede delivery, deployment or
general efficacy of the endovascular prosthesis after it has been
implanted.
[0110] Cover material 16 (FIG. 3) and 16a (FIG. 4) may also be
derived from a silicone-based material such as those commercially
available from NuSil Technology (Carpenteria, Calif.). A
non-limiting example of such material is derived from a
silicone-based dispersion commercially available from NuSil
Technology under trade name MED-6640. This material is usually
obtained as a liquid dispersion in an organic insolvent such as
xylene. The dispersion may be used as such or the viscosity thereof
bay he altered as desired by addition of further solvent.
[0111] Preferably, the cover material is attached to an otherwise
tubular stent structure. The means by which attachment may be
achieved is not particularly restricted. For example, the cover
material could be fixed to the appropriate spot on the stent using
a suitable adhesive. Alternatively, the cover material could be
sewn onto the stent. Those of skill in the art will conceive of a
number of other means by which the cover material may be fixed to
the stent structure.
[0112] In another embodiment, cover material 16 (FIG. 3) and 16a
(FIG. 4) may be made of the same material as the remainder of
prosthesis 10 (FIG. 3) and 10a (FIG. 4) but preferably suitably
modified to comprises a number of slits, microcuts, slots,
apertures or the like to reconcile the feature of impeding bodily
fluid (e.g., blood) therethrough with the feature of rendering the
cover material sufficiently flexible so as to permit delivery and
deployment of the expandable prosthesis.
[0113] With reference FIGS. 5-16, a preferred mode of deploying
endovascular prosthesis 10a will be illustrated. For sake of
illustration only, various of the structural details of
endovascular prosthesis 10a discussed above are omitted from FIGS.
5-16. Further, for illustrative purposes only, endovascular
prosthesis 10a shown in FIGS. 5-16 is constructed from a
plastically deformable material such as stainless steel, tantalum
or the like.
[0114] Thus, with reference to FIG. 5, there is illustrated a lumen
100 (this could be the ascending aorta referred to in FIG. 2 above)
having a blockage 105 disposed on a wall thereof. In accordance
with conventional catheterization techniques, initial steps (not
illustrated for clarity) involve disposing a guidewire 110 in lumen
100 such that the distal end of guidewire 10 is distal blockage
105. Thereafter, a guiding catheter 115 is disposed in a manner
such that the distal end of guide catheter 115 is proximal the
distal extremity of blockage 105.
[0115] Thereafter, endovascular prosthesis 10a disposed on a
balloon catheter 120, (or other suitable delivery system),
preferably comprising an elastomeric balloon at the distal end
thereof, is extended from guiding catheter 115 to expose distal
portion of section 11 of endovascular prosthesis 10a.
[0116] Thereafter, a balloon 122 disposed on the distal end of
balloon catheter 120 is expanded in a conventional manner. This
urges the distal end of section 11 of endovascular prosthesis 10a
against lumen 100 as shown in FIG. 6.
[0117] Next, balloon 122 is deflated and balloon catheter 120 is
retracted such that balloon 122 is near the proximal end of section
13 of endovascular prosthesis 10a--this is shown in FIG. 7.
[0118] Thereafter, balloon 122 is partially expanded to urge the
proximal end of section 13 of expandable prosthesis 10a against the
inside of guiding catheter 115--this is shown in FIG. 5.
[0119] Next, guiding catheter 115 is retracted as shown in FIG. 9.
Since the proximal end of section 13 of endovascular prosthesis 10a
is urged against the inside of guiding catheter 115 during this
step, this effectively results in relative extension of section 13
from section 11 of endovascular prosthesis 10a.
[0120] Next, balloon 122 of balloon catheter 120 is deflated and
balloon catheter 120 is repositioned such that balloon 122 is near
the overlapping region of sections 11 and 13 of endovascular
prosthesis 10a-see FIG. 10.
[0121] At this point, balloon 122 is expanded which results in
urging of sections 11 and 13 of endovascular prosthesis 10a against
lumen 100 as shown in FIG. 11.
[0122] Thereafter, guiding catheter 115 is retracted to expose the
entire expandable prosthesis 10a as shown in FIG. 12 and balloon
122 of balloon catheter 120 is repositioned to expand the proximal
end of section 13 against lumen 100.
[0123] FIGS. 13 and 14 illustrates successive expansion steps along
the length of endovascular prosthesis 10a with the result that it
is "remodeled" to occlude blockage 105.
[0124] Of course, while not specifically illustrated, it is
preferred that cover material 16a (FIG. 4) is positioned such that
it occludes blockage 105.
[0125] FIGS. 16 and 17 illustrate a preferred perfusion balloon
which is useful in the embodiment illustrated in FIGS. 5-15. The
perfusion balloon is particularly useful to permit continued blood
flow through lumen 100 during "remodeling steps" illustrated in
FIGS. 12-14.
[0126] With reference to FIGS. 8-24, deployment of an alternate
embodiment of the present endovascular prosthesis will be
described. As will be evident to those of skill in the art, FIGS.
18-24 illustrate deployment of an endovascular prosthesis in the
ascending aorta of a patient. For clarity, the endovascular
prosthesis is shown schematically as a series of hoops. Preferably,
these hoops would be effectively interconnected by a covering
material such that the longitudinal length of the prosthesis is
adjustable by an accordion-type movement. Further, the specific
aortic disease being treated is not shown, again for the purposes
of clarity only.
[0127] Thus, a guidewire 200 is navigated endovascularly to a
region of the ascending aorta 205 just proximal the patient's heart
(not shown). Thereafter, a combination of a sheath 210, a balloon
catheter 215 and an endovascular prosthesis 220 is delivered over
guidewire 200 to ascending aorta 205.
[0128] A balloon 225 disposed at the distal end of balloon catheter
215 is expanded slightly so as to be urged against a pair of hoops
230 just proximal a distal hoop 235 of prosthesis 220. Next, the
combination of sheath 210 and balloon catheter 215 are retracted
slightly in the direction of the arrow shown in FIG. 19. This
exposes distal hoop 235 from sheath 210 resulting in self-expansion
of distal hoop 235. Specifically, it is preferred that the hoops
comprised in endovascular prosthesis 220 are constructed from a
shape memory alloy such as Nitinol or the like.
[0129] With reference to FIGS. 19 and 20, balloon 225 of catheter
215 is deflated, catheter 215 is retracted and balloon 225 is
re-inflated so as to be urged against a pair of intermediately
disposed hoops 240--see FIG. 20 for the repositioning of balloon
225 of catheter 215.
[0130] Next, the combination of sheath 210 and balloon catheter 215
is retracted in the direction of the arrow shown in FIG. 20. This
results in exposure of successive hoops of endovascular prosthesis
220 as shown in FIG. 21. As more hoops of endovascular prosthesis
220 are exposed from sheath 210, it may be desirable to reposition
balloon 225 of catheter 215 as shown in FIG. 22. The repositioning
of balloon 225 of catheter 215 may be achieved as described above
with reference to FIGS. 19 and 20.
[0131] Continued retraction of the combination of sheath 210 and
balloon catheter 215 results in further hoops of endovascular
prosthesis 220 being exposed from sheath 210 as shown in FIG. 22.
With reference to FIG. 22, once the appropriate longitudinal length
of endovascular prosthesis 220 has been reached, balloon 225 of
catheter 215 is deflated and the combination of sheath 210 and
balloon catheter 215 is retracted as shown in FIG. 24 thereby
exposing a pair of proximally disposed hoops 245 of endovascular
prosthesis 220. Thus, in the illustrated embodiment (FIG. 24),
there is no substantial lengthening of the distance between
proximally disposed hoops 245 of endovascular prosthesis 220. Thus,
those who have skill in the art, will recognize that endovascular
prosthesis 220 is particularly advantageous since the longitudinal
length thereof mall be readily varied during implantation thereof
in the patient. This is particularly advantageous where the target
anatomy of the patient is subject to varying dimensions on a
patient-by-patient basis. Further, the approach illustrated in
FIGS. 18-24 is particularly advantageous since endovascular
prosthesis 220 may be deployed while maintaining perfusion through
the delivery system. Further, the present endovascular prosthesis
is advantageous since, during delivery thereof, undesirable
stretching and related stress to the aorta is minimized or avoided.
By avoiding such stretching of the aorta, placement of the
prosthesis can be more easily reconciled with pre-procedure
measurements which are taken to determine the appropriate length
and size of the vessel.
[0132] The present endovascular prosthesis may further comprise a
coating material thereon. The coating material may be disposed
continuously or discontinuously on the surface of the prosthesis.
Further, the coating may be disposed on the interior and/or the
exterior surface(s) of the prosthesis. The coating material can be
one or more of a biologically inert material (e.g., to reduce the
thrombogenicity of the prosthesis), a medicinal composition which
leaches into the wall of the body passageway after implantation
(e.g., to provide anticoagulant action, to deliver a pharmaceutical
to the body passageway and the like) and the like.
[0133] The present endovascular prosthesis is preferably provided
with a biocompatible coating in order to minimize adverse
interaction with the walls of the body vessel and/or with the
liquid, usually blood flowing through the vessel. The coating is
preferably a polymeric material, which is generally provided by
applying to the prosthesis a solution or dispersion of preformed
polymer in a solvent and removing the solvent. Non-polymeric
coating material may alternatively be used. Suitable coating
materials, for instance polymers, may be polytetraflouroethylene or
silicone rubbers, or polyurethanes which are known to be
biocompatible. Preferably, however, the polymer has zwitterionic
pendant groups, generally ammonium phosphate ester groups, for
instance phosphoryl choline groups or analogues thereof. Examples
of suitable polymers are described in International Publication
Numbers WO 93/16479 and WO 93/15775. Polymers described in those
specifications are hemo-compatible as well as generally
biocompatible and, in addition, are lubricious. It is important to
ensure that the surfaces of the prosthesis are completely coated in
order to minimize unfavourable interactions, for instance with
blood, which might lead to thrombosis in the parent vessel.
[0134] This good coating can be achieved by suitable selection of
coating conditions, such as coating solution viscosity, coating
technique and/or solvent removal step.
[0135] While this invention has been described with reference to
illustrative embodiments and examples, the description is not
intended to be construed in a limiting sense. Thus, various
modifications of the illustrative embodiments, as well as other
embodiments of the invention, will be apparent to persons skilled
in the art upon reference to this description. For example, those
of skill in the art will appreciate that it is possible to modify
the specific embodiment illustrated in FIGS. 3 and 4 such (i.e., a
partially covered endovascular prosthesis) that the prosthesis is
completely cover or completely uncovered. Further, in the event the
prosthesis is partially or completely covered, it is possible to
utilize a bioadhesive or the like to promote sealing engagement of
the coveted portion of the prosthesis and the section of the body
passageway against which it is urged. It is therefore contemplated
that the appended clams still cover any such modifications or
embodiments.
[0136] All publications, patents and patent applications referred
to herein are incorporated by reference in their entirety to the
same extent as if each individual publication, patent or patent
application was specifically and individually indicated to be
incorporated bag reference in its entirety.
* * * * *