U.S. patent application number 09/728780 was filed with the patent office on 2001-03-15 for methods and apparatus for crossing vascular occlusions.
Invention is credited to Aguilar, Amiel, Campello, Mark, Co, Fred, French, Ronald, Milo, Charles F., Selmon, Matthew R..
Application Number | 20010000041 09/728780 |
Document ID | / |
Family ID | 22591864 |
Filed Date | 2001-03-15 |
United States Patent
Application |
20010000041 |
Kind Code |
A1 |
Selmon, Matthew R. ; et
al. |
March 15, 2001 |
Methods and apparatus for crossing vascular occlusions
Abstract
Methods and apparatus for crossing totally to substantially
occluded blood vessels by passing a redirectable wire such as a
guidewire from a relatively proximal point past the occlusion
within a subintimal space formed between the intimal layer and the
adventitial layer of a blood vessel wall. The wire may be advanced
to a point distal to the occlusion, and thereafter deflected back
into the blood vessel lumen, typically using a deflecting catheter
which is advanced over the guidewire after it has been positioned
within the subintimal space. The deflecting catheter may include a
flapper valve assembly or preformed actuator wire for redirecting
the guidewire. After the guidewire is returned to the blood vessel
lumen, the deflecting catheter may be withdrawn, and the guidewire
may be available for introduction of other interventional and
diagnostic catheters for performing procedures such as
stenting.
Inventors: |
Selmon, Matthew R.;
(Atherton, CA) ; Milo, Charles F.; (San Mateo,
CA) ; Co, Fred; (Santa Clara, CA) ; Campello,
Mark; (Millbrae, CA) ; French, Ronald; (Palo
Alto, CA) ; Aguilar, Amiel; (Palo Alto, CA) |
Correspondence
Address: |
WILSON SONSINI GOODRICH & ROSATI
650 PAGE MILL ROAD
PALO ALTO
CA
943041050
|
Family ID: |
22591864 |
Appl. No.: |
09/728780 |
Filed: |
November 30, 2000 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09728780 |
Nov 30, 2000 |
|
|
|
09163854 |
Sep 30, 1998 |
|
|
|
Current U.S.
Class: |
600/585 ;
128/898 |
Current CPC
Class: |
A61B 2017/22044
20130101; A61M 2025/0197 20130101; A61B 2018/00392 20130101; A61B
2017/22095 20130101; A61B 2017/22077 20130101; A61B 17/3207
20130101; A61M 2025/018 20130101; A61B 2017/003 20130101; A61M
25/01 20130101; A61B 2017/00247 20130101; A61B 2017/00252 20130101;
A61B 2090/3925 20160201 |
Class at
Publication: |
600/585 ;
128/898 |
International
Class: |
A61B 019/00; A61M
025/09 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 19, 1997 |
JP |
9-351217 |
Claims
What is claimed is:
1. A guidewire deflection system comprising: a catheter body having
a proximal end, a distal end, a longitudinal axis, and at least one
lumen extending along the catheter body; a nosecone formed at the
distal end of the catheter body having a distal opening in
communication with the catheter body lumen, a lateral opening
spaced relatively proximal to the distal opening that is in
communication with the catheter body lumen, and an inclined surface
formed proximally adjacent to the lateral opening; and a cannula
having a proximal end, a distal end, and at least one passageway
extending through at least a distal portion of the cannula, wherein
the distal end of the cannula is configured to deflect away from
the longitudinal axis of the catheter body when the distal end
thereof engages the inclined surface adjacent to the lateral
opening.
2. A guidewire deflection system as recited in claim 1, wherein the
distal portion of the cannula has a pre-formed shape resilient
curve and is slidably positioned within the lumen of the catheter
body, and wherein the distal portion has a relatively axially
aligned configuration with the lumen when the cannula is positioned
within the catheter body, and a relatively curved configuration
with the lumen when the cannula travels along the inclined surface
and through the lateral opening of the catheter body when the
cannula is distally advanced through the lumen within the catheter
body.
3. A guidewire deflection system as in claim 2, wherein the
pre-formed shape resilient curve at the distal portion of the
cannula extends over an arc in the range from 15 to 135
degrees.
4. A guidewire deflection system as in either claim 2, wherein the
pre-formed shape resilient curve has a radius in the range from 1
mm to 20 mm.
5. A guidewire deflection system as recited in claim 1, wherein the
cannula is configured for slidable movement through the lateral
opening.
6. A guidewire deflection system as recited in claim 1, further
comprising a guidewire configured to pass through the passageway of
the cannula.
7. A guidewire deflection system as recited in claim 6, wherein the
guidewire is configured for slidable movement through the distal
opening of the nosecone.
8. A guidewire deflection system as recited in claim 6, wherein the
guidewire has a sharpened distal tip.
9. A guidewire deflection system as in claim 6, wherein the
guidewire comprises means for imaging tissue surrounding the
wire.
10. A guidewire deflection system as in claim 1, wherein the
cannula is formed with a self-penetrating distal end.
11. A guidewire deflection system as recited in claim 10, wherein
the self-penetrating distal end includes a sharpened distal
tip.
12. A guidewire deflection system as recited in claim 1, wherein
the cannula includes a radiopaque marker substantially near its
distal end.
13. A guidewire deflection system as recited in claim 1, wherein
the distal end of the cannula includes a radiopaque marker.
14. A guidewire deflection system as recited in claim 1, wherein
the distal end of the catheter body includes a fluoroscopically
visible marker substantially near its distal end to permit visual
determination of the rotational orientation of the nosecone.
15. A guidewire deflection system as in claim 1, wherein the
nosecone is formed with a substantially circular cross-section.
16. A guidewire deflection system as in claim 1, wherein the
nosecone is formed with a wedge shaped cross-section.
17. A guidewire deflection system as in claim 1, wherein the
nosecone is formed with a substantially elliptical
cross-section.
18. A guidewire deflection system as in claim 1, further comprising
a hub rotationally secured to the proximal end of the catheter body
to controllably rotate the cannula and the catheter body.
19. A guidewire deflection system as in claim 18, wherein the hub
includes a cannula controller connected to the cannula for
controlling the slidable movement of the cannula within the
catheter body.
20. An intravascular catheter comprising: a catheter shaft having a
distal end and a longitudinal lumen; a nosecone positioned at the
distal end of the catheter shaft having a first port in
communication with the longitudinal lumen formed with a first
transverse cross-sectional area, and a second port in communication
with the longitudinal lumen formed with a second transverse
cross-sectional area relatively smaller than the first transverse
cross-sectional area; a cannula having a passageway that is
slidably positioned within at least a portion of the longitudinal
lumen of the catheter shaft, and is configured for passage through
the first port but not through the second port of the nosecone; and
a guidewire that is slidably disposed within at least part of the
cannula passageway and is configured for passage through the second
port.
21. An intravascular catheter as recited in claim 20, wherein the
nosecone includes an imaging component that provides directional
orientation.
22. An intravascular catheter as recited in claim 20, wherein the
nosecone includes a radiopaque marker.
23. An intravascular catheter as recited in claim 20, wherein the
nosecone defines the first port as a substantially circular orifice
and the second port as a substantially elliptical orifice.
24. An intravascular catheter as recited in claim 23, wherein the
nosecone further defines an inclined surface leading to the second
port.
25. An intravascular catheter as recited in claim 24, wherein the
nosecone defines the first port and the second port, further
defines an inclined surface.
26. A redirectable intravascular guidewire catheter comprising: a
catheter shaft having a distal end, a proximal end, a longitudinal
axis, and at least one lumen extending along at least a portion of
catheter shaft; and a guidewire deflector formed at the distal end
of the catheter shaft having a distal end port, a lateral port, and
a flapper assembly with a deflectable extension having a first
position that directs a guidewire tip through the distal end port
when the guidewire tip is positioned relatively distal to the
deflectable extension, and a second position that directs the
guidewire tip through the lateral port when the tip is positioned
relatively proximal to the deflectable extension and advanced
thereafter in a relatively distal direction.
27. A redirectable intravascular guidewire catheter as recited in
claim 26 further comprising a guidewire that is slidably positioned
within the lumen of the catheter shaft.
28. A redirectable intravascular guidewire catheter as recited in
claim 26, wherein at least a portion of the flapper assembly is
formed of a radiopaque material to provide an orientation marker
for directional placement of a guidewire.
29. A redirectable intravascular guidewire catheter as recited in
claim 26, wherein the flapper assembly is formed with a relatively
distal collar that is positioned substantially adjacent to the
distal end port.
30. A redirectable intravascular guidewire catheter as recited in
claim 26, wherein the distal collar is includes radiopaque
material.
31. A redirectable intravascular guidewire catheter as recited in
claim 26, wherein the distal end of the catheter shaft is formed
with an exterior surface, and wherein the relatively distal collar
of the flapper valve is positioned on the exterior surface of the
distal end of the catheter shaft.
32. A redirectable intravascular guidewire catheter as recited in
claim 26, wherein the guidewire deflector and the catheter shaft
are integrally formed.
33. A redirectable intravascular guidewire catheter as recited in
claim 26, wherein the proximal end of the catheter shaft includes a
stainless steel wire, and wherein the catheter shaft is formed with
an opening relatively distal to the wire for passage of a
guidewire.
34. A redirectable guidewire catheter comprising: a catheter shaft
formed with a distal end, and having a first lumen and a second
lumen each extending along the catheter shaft respectively to a
first distal opening and a second distal opening; an actuator wire
slidably positioned within the first lumen of the catheter shaft,
wherein the actuator wire is formed with a preformed distal end to
provide an actuated position that is biased towards the second
distal opening when advanced relatively distal through the first
distal opening; and a guidewire slidably positioned within the
second lumen of the catheter shaft that may be deflected when
advanced relatively distal through the second distal opening and
when the actuator wire is placed in its actuated position.
35. A redirectable guidewire catheter as recited in claim 34,
wherein at least a portion of the actuator wire is formed of a
half-cylinder hypotube.
36. A redirectable guidewire catheter as recited in claim 34,
wherein the preformed distal end of the actuator wire is formed
with a arc-shaped cross-section.
37. A redirectable guidewire catheter as recited in claim 34,
wherein the actuator wire extends beyond the outer surface of the
catheter shaft.
38. A redirectable guidewire catheter comprising: a catheter shaft
formed with a distal portion and a longitudinal axis, and wherein
the catheter shaft has a first lumen and a second lumen each
extending within the distal portion of the catheter shaft; a
nosecone formed at the distal portion of the catheter shaft,
wherein the nosecone includes a distal orifice and an interior
region, and wherein the interior region of the nosecone is formed
with a tapered surface and is in communication with the first and
second lumens; an actuator wire formed with a distal tip that is
slidably positioned within the first lumen of the catheter shaft,
wherein the distal tip of the actuator wire is redirected
substantially away from the longitudinal axis of the catheter shaft
when advanced relatively distal along the tapered surface of the
nosecone and through the nosecone orifice; and a guidewire slidably
positioned within the second lumen of the catheter shaft that may
be deflected away from the longitudinal axis of the catheter shaft
by contacting the redirected actuator wire when the guidewire is
advanced relatively distal through the distal orifice.
39. A redirectable guidewire catheter as recited in claim 38,
wherein the catheter shaft has a distal most end, and wherein the
orifice is formed at the distal most end of the catheter shaft.
40. A redirectable guidewire catheter as recited in claim 39,
wherein the catheter shaft and the nosecone are integrally
formed.
41. A redirectable guidewire catheter as recited in claim 38,
wherein the first and the second lumen are arranged in a
side-by-side configuration.
42. An intravascular catheter for selectively deflecting a
guidewire comprising: a catheter body formed with a distal end and
a longitudinal lumen formed along at least a portion of the
catheter body; a support tube having a distal tube end, a proximal
tube end, a tube port formed at the distal tube end, and a conduit
formed within the support tube in communication with the tube port,
wherein the distal tube end is formed with a cut-out portion, and
wherein the support tube is slidably and rotatably positioned
within the longitudinal lumen of the catheter body; and a cannula
having a distal cannula end, a cannula port formed at the distal
cannula end, and at least one passageway extending through at least
a distal end portion of the cannula that is in communication with
the cannula port, wherein the distal portion of the cannula has a
pre-formed shape resilient curve, and wherein the cannula is
slidably positioned within the conduit of the support tube.
43. An intravascular catheter as recited in claim 42, wherein the
support tube has a longitudinal axis, and wherein the distal
portion of the cannula is relatively aligned with respect to the
longitudinal axis of the support tube when the cannula is
positioned within the support tube, and is relatively askew with
respect to the longitudinal axis of the support tube when the
distal cannula end extends beyond the distal end of the catheter
body.
44. An intravascular catheter as recited in claim 43, further
comprising a guidewire with a distal tip positioned within at least
a portion of the cannula passageway, wherein the distal tip of the
guidewire is deflected in substantially the same direction as the
distal portion of the cannula.
45. An intravascular catheter as recited in claim 43, wherein the
proximal tube end of the support tube is connected to a rotating
assembly to rotate the support tube relative to the catheter
body.
46. An intravascular catheter for selectively deflecting a
guidewire comprising: a catheter body formed with a distal end, a
catheter port formed at the distal end of the catheter body, a
longitudinal axis, and a longitudinal lumen extending within at
least a distal portion of the catheter body in communication with
the catheter port; a cannula having a distal cannula end, a cannula
port formed at the distal cannula end, and at least one passageway
formed within at least a distal portion of the cannula in
communication with the cannula port, wherein the cannula is
slidably positioned within the longitudinal lumen of the catheter
body; and a support tube connected to the distal cannula end,
wherein the support tube is formed with a distal tube end section,
a proximal tube end section, and a backbone connecting the distal
and the proximal tube end sections.
47. An intravascular catheter as recited in claim 46, wherein the
support tube is preformed with a predetermined shape to deflect the
distal cannula end away from the longitudinal axis of the catheter
body when the distal cannula end is extended past the distal end of
the catheter body.
48. An intravascular catheter as recited in claim 46, wherein the
distal cannula end is preformed with a predetermined shape that
deflects away from the longitudinal axis of the distal cannula end
when extended past the distal end of the catheter body.
49. An intravascular catheter as recited in claim 46, wherein the
cannula is slidably movable within the longitudinal lumen of the
catheter body.
50. An intravascular catheter as recited in claim 46, wherein the
backbone of the support tube includes a plurality of cut-out rib
sections.
51. A redirectable intravascular guidewire catheter comprising: a
catheter shaft having a distal end, a proximal end, a longitudinal
axis, a first port formed at the distal end of the shaft, a second
port spaced relatively proximal to the distal end of the shaft, and
at least one lumen extending along at least a portion of the
longitudinal axis of the catheter shaft in communication with the
first and second ports; and a guidewire deflector formed within a
distal extremity of the catheter shaft having a first surface that
directs an end portion of a guidewire between the catheter shaft
lumen and the first port, and a second surface that directs the end
portion of the guidewire between the catheter shaft lumen and the
second port.
52. The redirectable intravascular guidewire catheter as recited in
claim 51, wherein the guidewire deflector includes a flapper valve
having a first position that provides the first surface for contact
with the guidewire, and a second position that provides the second
surface for contact with the guidewire.
53. A method for crossing a substantially occluded blood vessel,
said method comprising: selecting a guidewire with a deflectable
distal tip configured for advancement within a lumen of a blood
vessel wall; creating a longitudinal dissection plane within a wall
the blood vessel by inserting the guidewire into blood vessel wall
from within the blood vessel lumen at a proximal location relative
to a vascular occlusion; forming a channel along the dissection
plane within the blood vessel wall by advancing the guidewire
within the blood vessel wall in a relatively distal direction; and
selectively deflecting the distal tip of the guidewire at a
relatively distal location relative to the proximal location back
into the blood vessel lumen.
54. A method as recited in claim 53, wherein the blood vessel is an
artery.
55. A method as recited in claim 54, wherein the artery is coronary
artery.
56. A method as recited in claim 53, further comprising performing
an interventional or diagnostic procedure over the guidewire.
57. A method as recited in claim 53, further comprising advancing
an interventional or diagnostic catheter over the deflected
guidewire from a position relatively proximal to the occlusion,
through the channel, and back into the blood vessel lumen.
58. A method as recited in claim 53, further comprising imaging the
occlusion and blood vessel lumen to identify their relative
location to the guidewire.
59. A method as recited in claim 58, wherein the blood vessel is an
artery and the imaging step comprises imaging from a position in a
vein adjacent to the artery.
60. A method as recited in claim 53, wherein the distal tip of the
guidewire is deflected by providing the guidewire tip with a
resilient curved end, and distally advancing the guidewire from a
constraining lumen into the blood vessel lumen.
Description
FIELD OF THE INVENTION
1. The present invention relates generally to medical devices,
kits, and methods used in the treatment of vascular occlusions.
More particularly, the invention relates to systems and procedures
for crossing chronic occlusions in blood vessels with guidewires
that may facilitate performance of subsequent treatment and
therapies including angioplasty, atherectomy and stenting
procedures.
BACKGROUND OF THE INVENTION
2. Cardiovascular disease is a leading cause of mortality worldwide
that can take on many different forms. A particularly troublesome
form of cardiovascular disease results when a blood vessel becomes
totally occluded with atheroma or plaque, referred to as a chronic
total occlusion. Until recently, chronic total occlusions have
usually been treated by performing a bypass procedure where an
autologous or synthetic blood vessel is anastomotically attached to
locations on the blood vessel upstream and downstream of the
occlusion. While highly effective, such bypass procedures are quite
traumatic to the patient. Recently, catheter-based intravascular
procedures have been utilized to treat chronic total occlusions
with increasing success. Catheter-based intravascular procedures
include angioplasty, atherectomy, stenting, and the like, and are
often preferred because they are much less traumatic to the
patient. Before such catheter-based treatments can be performed,
however, it is usually necessary to cross the occlusion with a
guidewire to provide access for the interventional catheter. In
some instances, crossing the occlusion with a guidewire can be
accomplished simply by pushing the guidewire through the occlusion.
The guidewire remains in the blood vessel lumen and provides the
desired access path. In many cases, however, the guidewire
inadvertently penetrates into the subintimal space between the
intimal layer and the adventitial layer of the blood vessel as it
attempts to cross the occlusion. Once in the subintimal space, it
is very difficult and impossible in many instances to direct the
guidewire back into the blood vessel lumen. In such cases, it will
usually be impossible to perform the catheter-based intervention
and other procedures may have to be employed that are relatively
more traumatic. Catheters and methods for forming lateral
penetrations through tissue to and from blood vessels past total
occlusions are described in U.S. Pat. Nos. 5,443,497; 5,429,144;
5,409,019; 5,287,861; WO 97/13463; and WO 97/13471. Catheters
having side guidewire entry ports spaced proximally from their
distal tips are also described in U.S. Pat. Nos. 5,464,395;
5,413,581; 5,190,528; 5,183,470; 4,947,864; and 4,405,314. These
and a variety of other specific interventional and pharmaceutical
treatments have been devised over the years with varying levels of
success for different applications.
SUMMARY OF THE INVENTION
3. The present invention provides methods and apparatus for
crossing substantial or total occlusions in blood vessels. It is an
object of the invention to traverse vascular occlusions or other
blockages formed within blood vessels in order to provide pathways
for the placement of guidewires or other interventional devices as
part of an overall effort to restore or provide adequate
circulation. It is advantageous to cross a substantially occluded
blood vessel by finding and/or creating a path with the least or
relatively low resistance through or around at least a portion of
the occlusion which may include travel along or between the layers
of a blood vessel wall in regions such as the subintimal space. The
invention further provides methods, kits, and apparatus which
facilitate crossing a chronic total occlusion in a blood vessel
with a guidewire. In particular, catheters, guides, or other
apparatus provided herein may be used with conventional or
specialized guidewires to direct or redirect the guidewires from a
subintimal space, or other areas between the different layers of a
blood vessel wall, back into the blood vessel lumen. The disclosed
apparatus include devices formed with relatively simple
construction, and may be used in a relatively straight-forward
manner.
4. One aspect of the invention provides apparatus for crossing a
vascular occlusion by directing a lead device such as a guidewire
around at a least a portion of the obstruction within the blood
vessel wall. A deflecting catheter may controllably deflect or
direct the guidewire through or around a vascular occlusion formed
within the natural lumen of the vessel, and may direct the
guidewire within a region in between the various layers of the
vessel wall to completely or partially circumvent the blockage. The
deflecting catheter may provide any combination of these
controllable movements to position the guidewire in a manner that
can facilitate interventional treatments such as stenting. Another
variation of the invention includes a guidewire deflection system
comprising a catheter body formed with at least one lumen extending
along its length, a nosecone formed at the distal end of the
catheter body having a distal and a lateral opening. The region
surrounding the lateral opening may include an adjacent inclined
surface. The distal opening and the lateral opening are both in
communication with the catheter body lumen. In addition, a cannula
may be included having a cannula port in communication with at
least one passageway extending through at least a distal portion of
the cannula. The distal end of the cannula may be configured to
communicate with the inclined surface adjacent to the lateral
opening to deflect the cannula away from the longitudinal axis of
the catheter body. The distal portion of the cannula may further
have a pre-formed shape resilient curve, and may be slidably
positioned within the lumen of the catheter body. The distal
portion may have a relatively axially aligned configuration with
the lumen when the cannula is positioned within the catheter body,
and a relatively curved configuration with the lumen when the
cannula travels along the inclined surface and through the lateral
opening of the catheter body when the cannula is distally advanced
through the lumen within the catheter body. The guidewire
deflection system may further comprise a guidewire configured to
pass through the passageway of the cannula. A variety of imaging
components or markers may be also positioned on various portions of
the wire, cannula or catheter body. A hub assembly rotationally
secured to the proximal end of the catheter body may be selected to
controllably rotate the cannula and the catheter body.
5. In yet another embodiment of the invention, an intravascular
catheter is provided having a catheter shaft formed with at least
one longitudinal lumen. A nosecone may be positioned at the distal
end of the catheter shaft having a first port in communication with
the longitudinal lumen formed with a first cross-sectional area,
and a second port in communication with the longitudinal lumen
formed with a second cross-sectional area, wherein the first
cross-sectional area is relatively larger that the second
cross-sectional area. A cannula may be slidably positioned within
at least a portion of the longitudinal lumen of the catheter shaft,
and may be configured for passage through the first port which is
relatively larger, but not through the second port of the nosecone
which is relatively smaller in size. A guidewire may be also
slidably positioned within at least a portion of the cannula
passageway, and may be configured for passage through an inclined
surface formed adjacent to the second port. The nosecone may
further include imaging components or radiopaque markers that
provides directional orientation.
6. Another embodiment of the invention provides a redirectable
intravascular guidewire catheter. The catheter may be formed with a
catheter shaft and a guidewire deflector formed at the distal end
of the catheter shaft. The guidewire deflector may be formed as a
nosecone assembly having a distal end port, a lateral port, and a
relatively internal or external flapper assembly with a deflectable
extension. The deflectable extension of the flapper assembly may
have a first position that directs a guidewire tip through the
distal end port when the guidewire tip is positioned relatively
distal to the deflectable extension. It may further have a second
position that directs the guidewire tip through the lateral port
when the tip is positioned relatively proximal to the deflectable
extension and advanced thereafter in a relatively distal direction.
Additionally, a guidewire may be included in the catheter that is
slidably positioned within the lumen of the catheter shaft. A
portion of the flapper assembly may be also formed of a
fluoroscopic material to provide an orientation marker for
directional placement of a guidewire.
7. A redirectable guidewire catheter is further provided in
accordance with the concepts of the invention comprising a catheter
shaft, an actuator wire, and guidewire. The catheter shaft may be
formed with a first lumen and a second lumen each extending along
the catheter shaft respectively to a first distal opening and a
second distal opening. The actuator wire may be slidably positioned
with the first lumen of the catheter shaft, wherein the actuator
wire is formed with a preformed distal end to provide an actuated
position that is biased towards the second distal opening when
advanced relatively distal through the first distal opening.
Furthermore, the actuator wire may extend only within or beyond the
outer surface of the catheter shaft at a relatively distal or
distal most end portion of the catheter shaft. The guidewire may be
slidably positioned within the second lumen of the catheter shaft,
and may be deflected when advanced relatively distal through the
second distal opening when the actuator wire is placed in its
actuated position. In another variation of the invention, the
redirectable guidewire catheter may have a catheter shaft with a
first lumen and a second lumen each extending along the catheter
shaft. A nosecone may be formed at the distal portion of the
catheter shaft, wherein the nosecone includes a distal orifice and
an interior region formed with a tapered surface. The actuator wire
may be formed with a distal tip that is slidably positioned with
the first lumen of the catheter shaft, wherein the distal tip of
the actuator wire is redirected substantially away from the
longitudinal axis of the catheter shaft when advanced relatively
distal along the tapered surface of the nosecone and through the
nosecone orifice. The guidewire may be slidably positioned within
the second lumen of the catheter shaft, and may be deflected away
from the longitudinal axis of the catheter shaft by contacting the
redirected actuator wire when the guidewire is advanced relatively
distal through the distal orifice.
8. Yet another variation of the invention provides an intravascular
catheter for selectively deflecting a guidewire that includes a
catheter body formed with a distal end and a longitudinal lumen
formed along at least a portion of the catheter body. A support
tube may be formed with a distal tube end that includes a cut-out
portion to accept the distal portion of a cannula. The support tube
may be slidably and rotatably positioned within the longitudinal
lumen of the catheter body. The cannula may include at least one
passageway extending through at least a distal end portion of the
cannula, wherein the distal portion of the cannula has a pre-formed
shape resilient curve that may communicate with the cut-out portion
when the cannula is slidably positioned within the conduit of the
support tube. The proximal tube end of the support tube may be
connected to a rotating assembly to rotate the support tube
relative to the catheter body. Another variation of the
intravascular catheter may include a support tube connected to the
distal cannula end, wherein the support tube is formed with a
distal tube end section, a proximal tube end section, and a
backbone connecting the distal and the proximal tube end sections.
The support tube or the distal cannula end may be preformed with a
predetermined shape to deflect the distal cannula end away from the
longitudinal axis of the catheter body when the distal cannula end
is extended proximally past the distal end of the catheter
body.
9. Another aspect of the invention provides methods for crossing a
substantially occluded blood vessel. The method may include the
steps of selecting a guidewire with a deflectable distal tip
configured for placement in a blood vessel wall, creating a
longitudinal dissection plane within the blood vessel wall by
inserting the guidewire into blood vessel wall from within the
blood vessel lumen at a proximal location relative to a vascular
occlusion, forming a channel along the blood vessel wall by
advancing the guidewire in a relatively distal direction along the
blood vessel wall, and selectively deflecting the distal tip of the
guidewire at a relatively distal location relative to the proximal
location back into the blood vessel lumen. An interventional or
diagnostic catheter may be advanced over the deflected guidewire
from a position relatively proximal to the occlusion, through the
channel, and back into the blood vessel lumen.
10. Other variations of the invention described herein also include
methods where total occlusions are crossed by first forming a track
or channel from a lumen in a blood vessel into a subintimal space
between an intimal layer and an adventitial layer of the blood
vessel. The track may be formed so that it extends from a location
proximal of the total occlusion to a location which is relatively
distal to the total occlusion, or at any positioned located
therebetween. A passage may be then formed from the track back into
the blood vessel lumen at the relatively distal location. In one
variation of the invention, the track may be formed by advancing a
wire through the blood vessel lumen into the subintimal space by
typically advancing the wire until it encounters the total
occlusion. By continuing to advance the wire in a generally distal
direction, it may pass into the subintimal space of the blood
vessel, and may be further advanced toward a desired distal
location. After the wire is located or confirmed at a point
relatively distal to the total occlusion or original point of
insertion, it may be typically deflected from the track or channel
back into the blood vessel lumen.
11. In some exemplary methods described herein, the wire may be
deflected using a deflecting catheter. Typically, the deflecting
catheter may be advanced over a proximal end of the wire and
advanced into the track within the subintimal space. The wire and
the deflecting catheter may be manipulated so that the wire is
deflected laterally through the intimal layer back into the blood
vessel lumen. Such deflecting catheters may be also useful in
axially supporting the wire as it is advanced into and/or through
the track, i.e. the catheter can enhance the "pushability" of the
wire when it is advanced forward through any resisting material.
Specific designs for such deflecting catheters are described in
detail below. The wire, which is initially positioned within the
track in the subintimal space, may be alternatively withdrawn
through the deflecting catheter and exchanged for a second wire or
device suitable for penetrating through the intimal layer of the
blood vessel wall back into the lumen. It will be appreciated that
the wires and/or deflecting and other catheters may be freely
exchanged over or through one another in a conventional matter
without departing from the scope of the invention.
12. Various imaging techniques may be used in accordance with the
invention to determine where the wire and/or deflecting catheter
are positioned with respect to a vascular occlusion so that the
wire may be returned to the blood vessel lumen at a desired
location or beyond the occlusion. For example, the position
determination can be made by fluoroscopically imaging the blood
vessel in a conventional manner. Alternatively or additionally to
such fluoroscopic imaging, intravascular imaging, e.g.
intravascular ultrasonic imaging (IVUS), and a variety of optical
imaging modelities, such as optical coherence tomography (OCT), may
be employed. For example, an ultrasonic imaging guidewire may be
used to initially access the subintimal space and/or may be
exchanged for the wire which is used to access the subintimal
space. An imaging guidewire present in the subintimal space may
readily detect the presence or absence of occluding material within
the blood vessel lumen. The transition from detecting occluding
material to the lack of the same is a strong indication that the
position of the guidewire has advanced beyond the total occlusion.
The wire may be deflected thereafter and returned towards the blood
vessel lumen. After a passageway is formed from the track or
channel back into the blood vessel lumen, and a wire is in place
across the total occlusion, the wire may be used as a guidewire for
positioning interventional and diagnostic catheters across the
obstruction. Interventional catheters are often positioned across
the total occlusion for treating the occlusion, and include devices
such as angioplasty balloon catheters, rotational atherectomy
catheters, directional atherectomy catheters, and stent-placement
catheters.
13. Another aspect of the invention provides methods for crossing a
vascular occlusion with a deflecting wire. The wire deflecting step
may include deflecting a cannula from the subintimal space of a
blood vessel wall back into the blood vessel lumen, and thereafter
passing the wire through a path defined by the cannula, typically
by a lumen within the cannula. The cannula may be advanced over the
wire after the wire is disposed or advanced within the subintimal
space, and a cannula-deflecting step may be also included that
involves distally advancing a resilient or preformed curved end
portion of the cannula from a constraining lumen formed within a
surrounding catheter or sheath back into the blood vessel lumen.
Alternatively, a wire-deflecting step may comprise advancing a
deflecting catheter over the wire which has been advanced into the
subintimal space. A cannula may then be advanced through a lateral
opening of the deflecting catheter, and penetrate through the
intimal layer to define a path for the wire back into the blood
vessel lumen. A wide variety of steerable and actively deployed
cannulas may also be used in the foregoing applications.
14. The present invention further provides kits for crossing
vascular occlusions comprising a wire-deflecting catheter having a
lumen or mechanism capable of laterally deflecting a wire. The kit
may further comprise instructions setting forth any of the methods
described above. Other methods and apparatus formed in accordance
with the invention, as specifically described herein, may be also
combined to provide numerous kits for many applications as in the
treatment of coronary artery and peripheral vascular occlusions.
Optionally, the kits provided herein may further comprise a wire
for penetrating into the subintimal space and/or back into the
blood vessel lumen. The kit may still further comprise a package
for containing a wire deflecting catheter, instructions for its use
as described in the various methods herein described, and other
optional devices including additional wire(s). Suitable packages
include pouches, trays, tubes, boxes, and the like. The
instructions may be printed on a separate package insert or may be
printed in part or in whole on the packaging itself. The components
of the kit within the package may be sterilized by conventional
procedures.
15. Apparatus according to another aspect of the invention provides
wire-deflection systems. Exemplary wire-deflection systems usually
comprise a wire-deflecting catheter which includes a catheter body
and a deflecting cannula. The catheter body has a proximal end, a
distal end, and at least one lumen extending through at least a
distal portion thereof. The lumen also has a distal opening and a
lateral opening. In addition, the cannula has a proximal end, a
distal end, and at least one lumen extending through a distal
portion thereof. The distal portion of the cannula may also have a
preformed, resilient curve. The cannula is slidably disposed within
the lumen of the catheter body to assume (a) a straightened
configuration when the cannula is proximally retracted within the
catheter body lumen and (b) a curved configuration when the cannula
is extended laterally through the lateral opening of the catheter
body. In this way, the cannula can be selectively deflected through
the intimal layer of the blood vessel back into the lumen of the
blood vessel according to some of the preferable methods described
herein. The system may further comprise a wire configured to pass
through the cannula lumen. The wire may be a conventional guidewire
or a modified wire having a sharpened distal tip intended
particularly for penetrating the intimal layer of the blood vessel
wall. Optionally, the wire may further comprise an imaging
apparatus such as an ultrasonic imaging means. The catheter body
may include a fluoroscopically visible marker near its distal end.
The marker can be configured to permit visual determination of the
rotational orientation of the distal end of the catheter body when
viewed as a two-dimensional fluoroscopic image. The catheter body
will usually be reinforced to enhance torsional rigidity, and may
further comprise a distal nose cone wherein the distal and lateral
openings are defined within the nose cone. The distal end of the
cannula will usually be pre-formed in a smooth curve which may
extend over an arc in the range from about 15 to 135 degrees,
usually from about 45 to 90 degrees. The preformed curve may also
have a radius in the range from approximately 0.5 mm to 15 mm,
usually from approximately 2 mm to 10 mm. These and other objects
and advantages of the invention will become more apparent upon
further consideration of the entire specification and drawings.
Additional aspects and details of the invention will become more
apparent to those skilled in the relevant are upon review of the
following detailed description of the invention set forth
below.
BRIEF DESCRIPTION OF THE DRAWINGS
16. FIG. 1 is a schematic illustration of a coronary artery showing
the intimal layer, the medial layer, and the adventitial layer.
17. FIG. 2 is a schematic illustrations of a total occlusion within
the coronary artery of FIG. 1, shown in full section.
18. FIGS. 3A-3D illustrate the method of the present invention for
crossing a total occlusion with a wire using a deflecting
catheter.
19. FIG. 3BB illustrates an alternate guidewire advancement step
for the method of FIGS. 3A-3D.
20. FIG. 4 illustrates the distal end of a deflecting catheter
formed in accordance with the invention.
21. FIG. 5 illustrates the distal end of another deflecting
catheter useful in the methods of the present invention.
22. FIG. 6 illustrates the distal end of another embodiment of the
invention that provides a deflecting catheter.
23. FIG. 7 illustrates a wire-deflecting catheter system formed in
accordance with the present invention.
24. FIGS. 8-9 are cross-sectional views of the distal end of a
catheter similarly shown FIG. 7, illustrating an internal cannula
in a retracted and advanced configuration, respectively.
25. FIG. 10 is a schematic illustration of a proximal hub of a
catheter for deflecting and directing a guidewire in accordance
with the methods and apparatus of the invention.
26. FIGS. 11A-11B illustrate variations for rotationally keying the
proximal end of catheter shafts.
27. FIG. 12 illustrates variations for rotationally keying the
distal end of a catheter.
28. FIGS. 13A-C provide illustrations of a nosecone for a guidewire
deflection catheter system formed in accordance with the
invention.
29. FIGS. 14A-B are cross-sectional side views of a nosecone
connected to the distal end of a catheter shaft with an internally
positioned cannula and guidewire.
30. FIGS. 15A-E are simplified side views of a flapper mechanism
positioned at the distal portion of a catheter that controllably
deflects a guidewire through a distal end port and/or a lateral
port.
31. FIGS. 16A-B are simplified side views of external guidewire
deflecting mechanisms that are positioned relatively outer to the
catheter shaft body.
32. FIGS. 17A-E illustrate a redirectable guidewire catheter having
a preformed actuator wire that deflects a slidable guidewire
positioned within an adjacent lumen.
33. FIGS. 18A-C show the distal section of a nosecone formed with a
single orifice that may be positioned at the distal end of a
redirectable guidewire catheter.
34. FIG. 19 is a simplified perspective illustration of the distal
portion of an intravascular catheter that includes a support tube
formed with a distal end portion for directing a preformed
cannula.
35. FIG. 20 is a simplified perspective illustration of the distal
portion of an intravascular catheter that includes a support tube
having a backbone for supporting the deflective movement of an
internally positioned cannula.
DETAILED DESCRIPTION OF THE INVENTION
36. The present invention provides methods and apparatus for
crossing a substantially or totally occluded blood vessel. Each of
the disclosed embodiments may be considered individually or in
combination with other variations and aspects of the invention. The
methods and apparatus provided herein may be useful in coronary
arteries and other blood vessels with or without assistance from
imaging techniques from various regions within the body including
areas within or adjacent to blood vessel walls. While the some
aspects of the invention may be particularly applicable for the
treatment of coronary artery disease, they are also useful and
equally applicable in the treatment of other arteries and veins,
and for other conditions including peripheral vascular
diseases.
37. As shown in FIG. 1, for example, a relatively normal
non-diseased artery (A) generally comprises an arterial wall formed
with a number of distinct layers. An innermost layer may be
referred to herein as the intimal layer (I) which includes the
endothelium, the subendothelial layer, and the internal elastic
lamina. A medial layer (M) of the blood vessel is located
concentrically outward from the intimal layer (I), and within
another layer known as the adventitial layer (AL) which may be
considered the relatively outermost layer. Beyond the adventitial
layer (AL) generally lies surrounding extravascular tissue. As used
hereinafter, the region between the intimal layer (I) and the
adventitial layer (AL), generally including the medial layer (M),
will be referred to as the subintimal space. It is generally the
subintimal space through which the wires, deflecting catheters, and
other catheters of the invention, will pass at least in part when
crossing a total of substantially occluded blood vessel. The
guidewires and deflecting catheters described herein may be formed
of appropriate dimensions for placement and travel within these
regions of the blood vessel wall. For most applications described
herein, it is most often preferable to travel within the layers of
the blood vessel wall, and across the inner wall of the blood
vessel into the vascular lumen, without penetrating the outer wall
region which would present additional safety concerns to a patient.
These methods and apparatus may be of course directed to any region
formed between other layers of a blood vessel wall other than those
particularly described above.
38. FIG. 2 provides an illustration of a total occlusion (TO)
within an artery (A) such as a coronary artery. The total occlusion
(TO) may comprise atheroma, plaque, thrombus, and/or other
occluding materials normally associated with cardiovascular
disease. A "total" occlusion may be described to include an
obstruction consisting of occluding material that substantially
blocks or occludes the entire lumen (L) of the artery (A), or any
other blood vessel, so that blood flow through the vessel is
substantially stopped or hindered. The invention may be
particularly applicable for patients with a totally occluded artery
that is not immediately life threatening since the tissue distal to
the occlusion may receive oxygenated blood from collateral arteries
and circulation. However, the blood supply is usually insufficient,
and it is often desirable to treat the occlusion by an
intravascular intervention, such as angioplasty, atherectomy,
stenting, or the like, to restore blood flow through the affected
vessel. Before most of these and other interventional procedures
can be performed, a guidewire is generally placed across the
occlusion. When a vascular occlusion prevents the placement of a
guidewire across the obstruction, one aspect of the invention thus
provides various methods for crossing the substantially or totally
occluded blood vessel. A guidewire may be initially selected with a
deflectable distal tip configured for placement within or in
between the layers of a blood vessel wall. A longitudinal
dissection plane may be created within the blood vessel wall by
inserting the guidewire into blood vessel wall from within the
blood vessel lumen at a proximal location relative to a vascular
occlusion. A channel may be formed in between the layers of and
along the blood vessel wall by advancing the guidewire in a
relatively distal direction along the blood vessel wall. Various
imaging procedures may be performed to identify the relative
location of the occlusion and blood vessel lumen. For example,
imaging of a coronary may be accomplished from a position in a vein
adjacent to the coronary artery. When the relative positioning of
the guidewire and the occlusion are verified, the distal tip of the
guidewire may be selectively deflected at a relatively distal
location relative to the proximal location back into the blood
vessel lumen. Upon placement of a guidewire across the vascular
occlusion, interventional or diagnostic procedures may be
subsequently performed over the guidewire, and more specifically,
the interventional or diagnostic catheter may be advanced over the
deflected guidewire from a position relatively proximal to the
occlusion, through the channel, and back into the blood vessel
lumen. The distal tip of the guidewire may be also deflected by
providing the guidewire tip with a resilient curved end, and
distally advancing the guidewire from a constraining lumen into the
blood vessel lumen.
39. Another aspect of the present invention provides methods of
crossing a vascular occlusion by controllably directing a
deflectable wire into and through a blood vessel wall as described
in FIGS. 3A-D. For purposes of illustration, this series of figures
may represent an upper portion of an occluded artery (A) as shown
in FIG. 2. A wire 10 may be advanced through the lumen (L) of an
artery (A), as shown in FIG. 3A, until it encounters a total
occlusion (TO). At that time, it may be possible for the wire 10 to
be distally advanced through the occlusion without deflecting into
the blood vessel wall. Should that occur, subsequent repositioning
or redirecting of the guidewire according to the methods of the
present invention may be performed, but may not be necessary. More
usually, however, the wire 10 is not able to traverse a substantial
occlusion by distally advancing the wire through the obstruction.
The wire 10 may likely advance into the subintimal space within the
medial layer (M) as shown in FIG. 3A. Of course, the wire 10 may
also travel into or around at least a portion of the total
occlusion (TO) before or while it is distally advanced. The intimal
layer (I) and the adventitial layer (AL) together may define a
tissue plane through which the wire 10 will naturally pass as the
wire is pushed distally from its proximal end. The wire 10 may
continue to advance further until its tip passes beyond the distal
end of the total occlusion (TO) as shown in FIG. 3B. The tip could
axially or distally advance well beyond the total occlusion to a
desired location or until advancement is ceased. Although the
guidewire 10 in FIG. 3B is shown as being advanced without support,
in some instances the guidewire may however encounter significant
resistance as it enters and/or passes through the space between the
intimal layer (I) and the adventitial layer (AL), or any other
layers within a blood vessel wall. When resistance is encountered,
the deflection catheter 20 may be used to axially support and
enhance the "pushability" of the guidewire 10 by advancing the
catheter over the proximal end of the guidewire to a location just
proximal of the distal tip of the guidewire as shown in FIG. 31BB.
The guidewire 10 and catheter 20 may then be advanced together or
sequentially, e.g. advancing the guidewire a short distance
followed by advancing the catheter, as needed to direct the distal
tip of the guidewire, or a lateral port 22 formed in the catheter,
to a relatively distal location which may be proximal to or past
the total occlusion (TO).
40. When the distal tip of the guidewire 10 is advanced to a
desired location without additional support from the deflecting
catheter 20, and is positioned beyond the total occlusion (TO), the
deflecting catheter may be advanced over the wire 10 by coaxial
introduction over the proximal end of the wire until it approaches
the total occlusion as shown in FIG. 3B. The deflecting catheter 20
may be further advanced over the wire 10 until its distal tip also
extends beyond the total occlusion (TO) as illustrated in FIG. 3C.
The deflecting catheter 20 includes a redirecting mechanism for
laterally deflecting the wire 10 so that it may pass back in a
radially inward direction through the intimal layer (I) back into
the blood vessel lumen (L) when the catheter is sequentially moved
in a relatively distal direction, and a relatively proximal
direction thereafter. Rather than advancing and withdrawing the
catheter 20 in a proximal direction, the guidewire 10 may be
withdrawn and advanced in a distal direction to be deflected. The
deflection mechanism may be selected from various redirecting
devices an may take a variety of forms as described below. For
example, as shown in FIG. 3C, a lateral port 22 is provided in the
deflecting catheter 20. The wire 10 may be retracted so that its
distal tip lies proximally of the lateral port 22, and may then be
advanced distally so that the wire passes laterally outwardly
through the port and back into the blood vessel lumen as shown in
FIG. 3D. Various deflecting catheters and apparatus described
herein for directing and redirecting a guidewire within a blood
vessel wall may be selected to perform these procedures in
accordance with the concepts of the invention.
41. The location and orientation of the deflecting catheter and
wire assembly may be monitored in various ways to carry out the
described methods for crossing a substantially occluded blood
vessel. In particular, it may be desirable to assure that the
distal tip of the wire 10 and the port 22 or other deflecting
mechanism of the deflecting catheter 20 is properly positioned
beyond the total occlusion (TO) without being advanced excessively
beyond the end of the total occlusion. Typically, it may be
desirable to position the deflecting mechanism at a range from
approximately 0 to 2 cm beyond the distal end of the total
occlusion (TO), and preferably from 0 to 0.5 cm. As discussed
above, the positioning of the relative components may in some
instances be performed using conventional fluoroscopic imaging. For
example, it may be sufficient to provide suitable radiopaque
markers on the wire and/or on the deflecting mechanism of the
deflecting catheter 20 to permit visual positioning and rotational
orientation of the tip via fluoroscopy. Often, however, it may be
desirable to provide ultrasonic or other imaging at or near the
total occlusion. A wire 10 may be thus provided with ultrasonic
imaging so that the presence and the absence of the occluding
material may be detected as the wire is advanced passed the total
occlusion (TO). Alternatively, the deflecting catheter 20 may be
provided with ultrasonic imaging in the form of a phased array
located near the distal tip (not shown). Ultrasonic imaging
guidewires are known to those skilled in the relevant field and are
described in the patent literature as in U.S. Pat. No. 5,095,911,
the full disclosure of which is incorporated herein by reference.
In yet another alternative, an imaging guidewire may be advanced to
the region of the total occlusion (TO) in a direction opposite to
that of the wire 10 and catheter 20. In this way, the imaging
guidewire need not advance through the total occlusion, but could
still detect advancement of the catheter and/or guidewire,
particularly if ultrasonically opaque components were provided on
either or both of the catheter and wire. In yet another
alternative, an ultrasonic imaging catheter or guidewire could be
positioned in a vein adjacent to the arterial occlusion site,
allowing imaging of the entire occluded region while the guidewire
is advanced there through. Other imaging modalities may be employed
including apparatus such as optical coherence tomography (OCT) (see
U.S. Pat. Nos. 5,321,501; 5,459,570; 5,383,467; and 5,439,000),
fluorescence imaging (see U.S. Pat. Nos. 4,718,417; and 5,106,387),
and Raman spectroscopy (WO 92/18008).
42. Another desirable feature of the methods prescribed by the
present invention includes the rotational positioning of the
deflecting catheter 20. It will be appreciated that the direction
of deflection is usually selective, and it will be therefore
desirable to aim the deflecting mechanism from the subintimal space
back toward the arterial or blood vessel lumen (L). If the catheter
22 is provided with ultrasonic imaging, such imaging can be used
for rotationally positioning the distal tip of the catheter. The
catheter may be rotationally rigid so that rotation of its proximal
end may position the distal end of the device in a substantially
similar manner or orientation. By detecting the presence or
relative location of the blood vessel lumen (L), the deflecting
port 22 or other deflecting mechanism can be properly positioned.
In an alternative embodiment, as further illustrated below, a
catheter may include a rotationally specific fluoroscopic marker,
preferably towards its distal end region. The marker may be such
that by observing the two-dimensional image of the marker by
fluoroscopic imaging, the rotational direction of the catheter tip
can be determined.
43. FIGS. 4-6 illustrate several exemplary deflecting mechanisms
for the catheters provided by the present invention. As shown in
FIG. 4, the distal end of a catheter 30 may have a distal port 32,
a lateral port 34, and a passive deflecting mechanism 36. The
passive deflecting mechanism may include a first and a second
inclined guiding surface 31 and 33. The first inclined guiding
surface 31 may be formed in a relatively distal position, and may
be formed to direct the proximal end of a guidewire (not shown)
into the main lumen of the catheter from the distal port 32. The
guidewire may be thereafter displaced relatively proximal to the
catheter so that the distal end of the guidewire approaches and
passes the passive deflecting mechanism 36 in a relatively proximal
direction. The second inclined guiding surface 33, which may be
formed in a relatively proximal position, may thereafter direct the
distal end of the guidewire in a deflected position through the
lateral port 34 when the guidewire engages the second surface 33
upon subsequent distal advancement of the guidewire. For example,
the catheter 30 may be advanced over the proximal end of a wire so
that the wire passes over the distal surface 31 of the deflecting
mechanism 36, and back into the main lumen of the catheter 30. In
general, the catheter 30 is advanced distally in an over the wire
manner relative to the guidewire when the distal tip of the
guidewire is believed to lie relatively distal to a vascular
occlusion within a blood vessel wall. The catheter 30 may be
advanced over the wire so the distal tip of the catheter enters the
subintimal space and approaches the distal end of the guidewire. By
retracting the distal end of the wire within the lumen of catheter
30 so that its distal tip is proximal to the deflecting mechanism
36, subsequent distal advancement of the wire thereafter will
engage the proximal surface 33 of the deflecting mechanism and
cause the wire to be deflected laterally through lateral port
34.
44. Several examples of active deflecting mechanisms for
redirecting a guidewire are illustrated in FIGS. 5-6. A catheter 40
may be formed with a distal port 42 and a lateral port 44 as shown
in FIG. 5. Rather than a passive deflecting mechanism, the catheter
40 may include an axially translatable cannula 46 having a
resilient, pre-formed distal tip which may be advanced through port
44 as shown with broken lines. The cannula 46 may include a lumen
which provides a guide path for the wire (not shown) when the
cannula is placed in a deflected or non-deflected position.
Meanwhile, the catheter 50 illustrated in FIG. 6 is similar to the
catheter 40 in FIG. 5, except that no lateral port is provided.
Instead, a cannula 52 having a preformed distal end may be advanced
and retracted out of a distal port 54 of the catheter 50 so that
its distal end can assume a laterally deflected shape as shown with
broken lines. It will be appreciated that these embodiments are
intended to be exemplary only, and a wide variety of other passive
and active deflecting mechanisms may be provided on deflecting
catheters for use in accordance with the concepts of the present
invention.
45. Referring now to FIGS. 7-10, an exemplary deflecting catheter
100 formed in accordance with the principles of the present
invention is described in detail according to relative catheter
sections. As shown generally in FIG. 7, the deflecting catheter 100
comprises a catheter body 102 having a distal end 104 and a
proximal end 106. Catheter body 102 includes a single lumen 108, as
shown in FIGS. 8-10, and a deflecting housing 110 secured to the
distal end 104 thereof. An actuator hub 1 12 may be secured to the
proximal end 106 of catheter body 102, and an axially translatable
cannula may be disposed within lumen 108. The cannula 114 may be
formed with a sharpened tip 116, typically formed from a metal,
hard plastic, composite, or the like, optimally being radiopaque.
Alternatively or additionally, it may be desirable to provide at
least one separate radiopaque marker or the cannula at or near its
distal end to facilitate visualization under fluoroscopic imaging.
A distal length 118 of the cannula 114 can be pre-formed with a
curved shaped as shown in FIGS. 7 and 9. A rotationally specific
radiopaque marker 120 may be mounted near the distal end of
catheter body 102. As illustrated, the marker has a generally
U-shaped or otherwise directional configuration so that the
rotational position of the distal end of the catheter body 102 will
be apparent when the marker is observed in a two-dimensional
fluoroscopic image.
46. The catheter 100 provides lateral deflection to the distal tip
of the cannula 114 which extends beyond the catheter body 102
through a lateral opening 122 in the deflector housing 110 as shown
in FIGS. 7-9. The deflector housing 110 also includes a distal port
124 to permit introduction of the catheter 100 over the proximal
end of a guidewire GW as illustrated in FIG. 8 with broken lines.
The guidewire GW passes through the distal port 124, and into the
distal end of the cannula 114, and may travel through a lumen of
cannula all the way to the proximal end of the catheter 100. The
distal length 118 of cannula 114 may be straightened and deflected
by axially retracting and advancing the cannula between the
configuration shown in FIGS. 8 and FIG. 9, respectively. The
cannula 114 may be formed with an appropriate diameter or
cross-section to permit its passage through the layers of blood
vessel wall and may range from approximately 1F to 4F. The cannula
114 may be formed of from a wide range of biocompatible materials
such as polyimide, PEEK or nitinol. Similarly, the guidewire GW
should also have dimensions that allow its travel through the
relatively thin layers of a blood vessel wall, and may range from
approximately 0.010 in. to 0.038 in. The GW may be a conventional
intravascular guidewire and may be formed of a variety of materials
including stainless steel and nitinol. The distal tip of the
cannula 114 may include a tissue penetrating element 116 to assist
the cannula in re-entering the lumen of a blood vessel from within
the wall region. The cannula 114 should provide sufficient
stiffness in order to transmit enough force to penetrate the inner
blood vessel wall but not enough so as traverse the outer vessel
wall to regions outside of the blood vessel. The tissue penetrating
element 116 may be formed of gold-plated stainless steel, platinum,
or platinum iridium alloy or other radiopaque materials.
47. FIG. 10 provides an illustration of an actuator hub 112
comprising a pair of coaxial, telescoping tubes 130 and 132. The
outer telescoping tube 132 may be connected to a proximal end of
cannula 114, typically by an adhesive 134 or any other connective
material. A proximal fitting 136 is further attached to the
proximal end of the outer telescoping tube 132 so that the assembly
of the cannula 114, the tube 132, and the fitting 136 may move
together as a unit through the hemostatic fitting 140 at the
proximal end of the hub 112. The hub 112 may further include a
rotational fitting 142 which permits the catheter body 102 to be
rotated relative to the hub body. The cannula 114 and catheter body
102 may be rotationally coupled or "keyed" together to limit or
prevent relative rotation, typically by keying within the hub
and/or near the distal end, so that rotation of the catheter body
causes a like rotation of the cannula as the catheter is
rotationally positioned within a blood vessel. A side branch 148
may be provided on hub 112 to permit perfusion and/or infusion
through the lumen 108 of catheter 102.
48. Keying at the proximal end of the catheter 100 can be achieved
in a variety of ways. For example, the telescoping tubes 130 and
132 can be provided with asymmetric, mating peripheral geometries,
such as oval cross-sections shown in FIG. 11A or triangular
cross-sections shown in FIG. 11B. Keying at the distal end can also
be achieved in a number of ways, such as providing-the catheter
body 102 with an asymmetric lumen 108' and the cannula 114' with a
mating cross-section, e.g. a D-shaped cross-section as illustrated
in FIG. 12. The ability to limit relative rotation of the cannula
114 within the catheter body 102 is advantageous since it may
ensure that the curved distal length 118 is properly oriented
(usually directed radially outwardly) when the tip 116 emerges
through the opening 122. In use, the catheter 100 may be advanced
over guidewire GW while the cannula 114 is retracted as shown in
FIG. 8. Once the catheter is properly positioned, the cannula 114
may be distally advanced as shown in FIGS. 7 and 9. Distal
advancement may be achieved by forwardly advancing the sleeve 132
in the hub 112 relative to the remainder of the hub so that the
cannulas move forwardly within the lumen 108 of the catheter body
102. Prior to advancing the cannula, the port 122 may be properly
positioned so that it is directed toward the blood vessel lumen by
rotating catheter body 102, typically using the rotational hub 142.
Conveniently, the physician may observe the marker 120 so that the
lateral port 122 can be directed in the proper radially inward
direction. After the cannula is advanced into the blood vessel, the
guidewire GW may then be advanced distally into the lumen, the
cannula 114 may be withdrawn proximally, and the entire catheter
assembly may be then withdrawn from over the guidewire leaving the
guidewire in place for introduction of other interventional and/or
diagnostic catheters.
49. The deflection of a guidewire and/or cannula from within a
vascular wall into the blood vessel lumen may be achieved by
numerous deflecting mechanisms as described herein. For example, as
shown in FIGS. 13A-C, a guidewire deflection system may be formed
with a deflection nosecone assembly attached to the distal end of a
catheter body. The nosecone assembly may be approximately 0.25 in.
in length, and may of course vary in shape and dimensions according
to particular applications. The catheter body (not shown) may
further include a proximal portion, a longitudinal axis, and at
least one lumen extending along at least a distal end portion
thereof. As shown in FIG. 13A, a nosecone 200 may be formed with a
distal opening 204, a relatively proximal and spaced apart lateral
opening 206, and an inclined surface 208 adjacent to the lateral
opening. The distal opening 204 of the nosecone 200 may have a
substantially circular cross-section ranging from approximately 2F
to 6F. The lateral opening 206 may be configured with an oblong or
elliptical cross-section with a relatively lateral diameter of
about 0.014-0.050 in., and a relatively longitudinal diameter of
about 0.050-0.200 in. as shown in FIG. 13B. The distal opening 204
and the lateral opening 206 may be spaced apart approximately 2-5
mm, and preferably about 3 mm, or at other various distances along
the nosecone 200, and may be both in communication with the
catheter body lumen as shown in FIG. 13C. The lateral opening 206
and adjacent inclined surface 208 may receive a cannula passing
therethrough from the catheter body lumen. In particular, the
cannula (not shown) may have an external cannula surface that is
configured and sized for slidable movement through the lateral
opening 206 specifically. The cannula may be formed with at least
one passageway extending through at least a distal portion thereof.
The distal end of the cannula may be configured to communicate with
the inclined surface 208 adjacent to the lateral opening so as to
deflect the cannula away from the longitudinal axis of the catheter
body when the cannula is advanced in a relatively distal direction.
Additionally, the distal portion of the cannula may have a
pre-formed shape resilient curve, and may be slidably positioned
within the lumen of the catheter body. The distal cannula portion
may have a relatively axially aligned configuration with the lumen
when the cannula is positioned within the catheter body, and may
have a relatively curved configuration with the lumen when the
cannula travels along the inclined surface 208 and through the
lateral opening 206 of the catheter body when the cannula is
distally advanced through the lumen within the catheter body. The
preformed shape resilient curve at the distal portion of the
cannula may extend over an arc in the range from approximately 15
to 135 degrees, and may have a radius in the range from
approximately 1 mm to 20 mm. The cannula may also include a
self-penetrating distal end that includes a sharpened distal tip.
Moreover, the cannula may include a radiopaque or orientation
marker substantially near its distal end or along any portion
thereof.
50. The guidewire deflection system may farther include a guidewire
configured to pass through a passageway formed in the cannula. The
guidewire (not shown) may be formed with an external guidewire
surface that is configured or sized for slidable movement through
the distal opening 204 of the nosecone 200, and may range from
approximately 0.010-0.038 in. When the guidewire is initially
placed within the layers of blood vessel wall along a selected
dissection plane, the distal opening 204 of the nosecone 200 may
receive the proximal end of the guidewire to permit its passage
therethrough and along a longitudinal lumen formed within a cannula
in the attached catheter body. The nosecone 200 may be tapered and
formed with a substantially circular or elliptical cross-section,
or may even have a wedge shaped cross-section or any other
configuration that may facilitate passage in between the vessel
layers along the selected dissection plane. Moreover, a hub (not
shown) may be rotationally secured to the proximal end of the
catheter body to controllably rotate the cannula and the catheter
body (see generally FIG. 10). The hub may further include a
controller connected to the cannula for controlling the slidable
movement of the cannula within the catheter body (see generally
FIG. 7). After the location and orientation of the distal tip of
the guidewire is ascertained, the guidewire may be deflected into
the blood vessel lumen by withdrawing the cannula and guidewire in
a relatively proximal direction so at least the distal tip of the
cannula is proximal to the lateral port 206 and the inclined
surface 208. The cannula may be then advanced in a relatively
distal direction so the tip of the cannula, which may be relatively
sharpened, engages the inclined surface 208 adjacent to the lateral
port 206. The guidewire may be advanced distally thereafter, and
relatively lateral deflection of the guidewire is thus achieved by
the deflection nosecone assembly. Additionally, the guidewire,
cannula, or catheter body may also include means for imaging tissue
surrounding the wire. The distal end of the catheter body may
include a fluoroscopically visible marker substantially near its
distal end to permit visual determination of the rotational
orientation of the nosecone 200. The nosecone 200 may likewise have
a variety of fluoroscopic markers.
51. FIGS. 14A-B provide additional illustrations of an
intravascular catheter that includes a guidewire deflection
assembly 210. The catheter may be formed with a pair of relatively
inner and outer shafts 212 and 214 that are coaxially positioned
with respect to each other. A nosecone portion 215 may be connected
to the-distal end 216 of the outer catheter shaft 214 by known
techniques in the art. Additionally, a cannula 220 may be
positioned within the catheter that is formed with a guidewire
passageway and an external cannula surface. The cannula 220 may be
connected to the inner shaft 212, and may be slidably positioned
within at least a portion of the longitudinal lumen 224 of the
outer catheter shaft 214. The cannula 220 may not necessarily
extend within the entire length of the catheter, and may be located
external to the catheter along some relatively proximal portion. As
shown in FIG. 14B, the distal end of the inner shaft 212 may come
in contact with the proximal end of the nosecone 215 when advanced
distally so as to controllably limit the extended length of the
cannula 220. The external surface of the cannula 220 may be
configured for selective passage of the cannula through a first or
lateral port 226 but not through a second or distal port 228 formed
in the nosecone 215. A guidewire 230 formed with an external
surface may be thus configured for passage through the distal port
228 too, and may be slidably positioned within at least a portion
of the cannula passageway. When the cannula 220 is positioned
relatively coaxial within the catheter, the guidewire 230 within
the cannula may be directed to enter or to exit the catheter
through the distal port 228. The first port 226 in the nosecone 215
may have a first transverse cross-sectional area, and may be in
communication with a longitudinal lumen 224 that is defined by the
inner walls of the outer shaft 214. The second port 228 may also be
in communication with the longitudinal lumen 224, wherein the
second port is formed with a second transverse cross-sectional
area. The first cross-sectional area may be relatively larger or
smaller than the second cross-sectional area, and are preferably
formed with different dimensions or configurations so selective
passage of the cannula 220 may be achieved.
52. A variety of imaging and orientation markers may be also
positioned along various portions of the guidewire 230, cannula 220
and/or catheter body. In particular, the nosecone 215 may include a
radiopaque marker or imaging componentry that provides directional
orientation of the distal portion of the catheter or the relative
direction in which the lateral port 226 is facing. The nosecone 215
may include ports of various sizes, and may define a first port 226
as a substantially elliptical orifice and the second port 228 as a
substantially circular orifice. The immediate area of nosecone 215
surrounding the first port 226 may define an inclined surface 232
for receiving a distal cannula tip section 234 that leads to the
first port.
53. Additional guidewire deflecting mechanisms provided in
accordance with the invention are shown in FIGS. 15-20. A flapper
assembly 240, as shown in FIGS. 15A-E, may be positioned at the
distal portion of a catheter to controllably deflect a guidewire
242. The flapper assembly 240 may be formed at the distal end of a
catheter shaft to provide a redirectable intravascular guidewire
catheter. The catheter shaft (not shown) may have a distal end, a
proximal end, a longitudinal axis, and at least one lumen extending
along at least a portion of catheter shaft and the longitudinal
axis of the catheter shaft. The flapper assembly 240 may have a
distal end port 244, a lateral port 246, and a flapper valve or
mechanism 248 with a deflectable extension 250. The deflectable
extension 250 may include a biased inclined surface which may have
multiple curved sections. Additionally, as shown in FIGS. 15A-B,
the deflectable extension 250 may have a first position or
configuration that directs a guidewire tip 254 through the distal
end port 244 when the guidewire tip is positioned relatively distal
to the deflectable extension 250. The deflectable extension 250 may
also have a second position that directs the guidewire tip 254
through the lateral port 246 when the tip is positioned relatively
proximal to the deflectable extension 250, and advanced thereafter
in a relatively distal direction as shown in FIGS. 15C-D. The
flapper valve 248 may be also formed with a relatively distal
collar 256 that is positioned substantially adjacent to the distal
end port 244. The distal collar 256 may be formed with a
longitudinal length defined by the distance between the lateral
port 246 and the distal port 244. At least a portion of the flapper
assembly 240, including the collar portion 256, may be formed of a
fluoroscopic or radiopaque material to provide an orientation
marker for directional placement of the guidewire 242.
54. In another variation of the invention, as shown in FIG. 16A,
the flapper mechanism 260 may be formed relatively externally or
relatively outer to the catheter body 262. The collar portion 266
of the flapper mechanism 260 may be positioned on the outer surface
of the catheter body 262 along a relatively distal portion or along
any other section of the same. Furthermore, the deflectable
extension 270 may be integrally formed or connected to the collar
266, and may extend through a relatively distal portion of the
lateral opening 264 into the interior lumen of the catheter body
262. Although the guidewire deflectors shown in the preceding
illustrations have been depicted as separate components, they may
be of course integrally formed from a single piece of suitable
material. In addition, as shown in FIG. 16B, a guidewire may be
inserted into the interior lumen of the catheter body 262 through
an opening 263 that may be formed relatively proximal to the
flapper mechanism 260. The guidewire may be still positioned in at
least a relatively distal portion of the interior catheter lumen. A
relatively rigid or stiff member 269, which may be formed of
stainless steel, may thus occupy a substantial proximal length of
the catheter body lumen, to provide improved torque
transmission.
55. FIGS. 17A-D illustrates the distal section of a redirectable
guidewire catheter. The redirectable guidewire catheter may
comprise a catheter shaft 280 formed with a first lumen 282 and a
second lumen 284 each extending along the catheter shaft
respectively to a first distal opening 286 and a second distal
opening 288. The catheter may include an actuator wire 290 slidably
positioned with the first lumen 282 of the catheter shaft 280. The
actuator wire 290 may be formed with a preformed distal end 292 to
provide an actuated position that substantially extends or is
biased towards the second distal opening 288 when advanced
relatively distal through the first distal opening 286. The second
distal opening 288 may be thus obstructed or at least covered in
part which will tend to direct a guidewire 285 passing through the
second lumen 284 and distal opening 288 away from the longitudinal
axis of the catheter shaft 280. The guidewire 285 may be slidably
positioned within the second lumen 284 of the catheter shaft 280,
and may be deflected when advanced relatively distal through the
second distal opening 288 and when the actuator wire 290 is placed
in its actuated position. As shown in FIG. 17A, the actuator wire
290 may extend through the first distal opening 286 of the first
lumen 282 and may still remain within an interior distal nosecone
portion 295 of the catheter. The distal most tip 294 of the
actuator wire 290 may be formed with a flattened portion that rests
on a relatively level surface within the nosecone portion.
Alternatively, the actuator wire 290 may be configured to extend
outside of or beyond the outer surface of the catheter body or
nosecone portion 295 (not shown). The first distal opening 286
and/or the second opening 288 may be formed at the distal most end
portions of the catheter shaft 280 or at some point relatively
proximal thereof. The first and second lumens 282 and 284, which
lead to their respective distal openings 286 and 288, may be formed
with a variety of cross-sectional configurations and positions
relative to one another. For example, as shown in FIG. 17B, the
actuator wire lumen 282 may be formed with a crescent or arc-shaped
configuration to guide an actuator wire 290 therethrough. The
guidewire lumen 284 may be formed with conventional circular
cross-section and positioned side-by-side relative to the actuator
wire lumen 282. The actuator wire lumen 282 may have an inner
radius of about 0.017 in., and an outer radius of about 0.014 in.
The guidewire lumen 284 may be also formed with a diameter of about
0.018 in. The outer diameter of the catheter shaft 280 may be about
0.036 in. These dimensions may be of course varied according to
particular applications. At least a distal portion of the actuator
wire 290 may be thus formed of a half-cylinder hypotube, as shown
in FIG. 17C, for slidable movement within the actuator wire lumen
282. This configuration may further guide or direct a guidewire 285
extending from the adjacent lumen 284. The actuator wire 290 may of
course have a proximal section formed with any other type of
cross-section, and may include only a distal section that is formed
with an arc-shaped region to controllably deflect the guidewire 285
in a predetermined direction.
56. FIGS. 18A-C illustrates the distal section of a nosecone
assembly 300 formed at the distal end of a redirectable guidewire
catheter. The catheter may be configured for crossing a
substantially occluded blood vessel, and may include a catheter
shaft formed with a distal portion and a longitudinal axis, and
wherein the catheter shaft has a first lumen and a second lumen
each extending along the catheter shaft (see generally FIG. 17B).
The first and the second lumen may be also configured in a
relatively side-by-side configuration along the catheter shaft. As
shown in FIG. 18A, a nosecone 300 may be formed at the distal
portion of the catheter shaft (not shown), and may include a single
distal orifice 302 and an interior region 304. The interior region
304 of the nosecone 302 may be formed with a tapered surface 306
that is shaped to contact an actuator wire 308. The actuator wire
308 may be slidably positioned with the first lumen of the catheter
shaft. The distal tip of the actuator wire 308 may be redirected
substantially away from the longitudinal axis of the catheter shaft
when advanced relatively distal along the tapered surface 306 of
the nosecone 300 and through the nosecone orifice 302. The actuator
wire 308 may remain within the interior region 304 of the nosecone
section 300, or it may extend further away from or beyond the
catheter shaft to penetrate tissue in adjoining area. A guidewire
310 may be also slidably positioned within the second lumen of the
catheter shaft. The guidewire 310 may be initially positioned
within the selected dissection plane within a blood vessel wall,
and may support positioning of the catheter in an over the wire
manner. When the catheter is passed over the proximal portion of
the guidewire and distally advanced, as shown in FIG. 18B, the
guidewire 310 may travel in a relatively linear fashion along the
longitudinal axis of the catheter shaft. However, when the distal
end of the guidewire 310 is retracted into the nosecone section
302, and the actuator wire 308 extended distally, subsequent
advancement of the guidewire will result in its deflection and
movement away from the catheter shaft in an askew manner. As shown
in FIG. 18C, the guidewire 310 is deflected away from the
longitudinal axis of the catheter shaft by contacting the
redirected actuator wire 308 when the guidewire is advanced
relatively distal through the distal orifice 302. The orifice 302
may be formed at the distal most end of the catheter shaft or along
any relatively proximal portion thereof. The catheter shaft and the
nosecone 302 may be integrally formed or separately formed and
joined together by conventional techniques.
57. FIG. 19 illustrates another embodiment of the invention that
provides an intravascular catheter for selectively deflecting a
guidewire. The catheter body 320 may be formed with a longitudinal
lumen that includes a support tube 322 slidably and rotatably
positioned within the longitudinal lumen of the catheter body. The
support tube 322 may have a distal tube end and a tube port 324,
and may also define a conduit that is in fluid communication with
the tube port. The distal tube end may be also formed with a
cut-out portion 326. The catheter may also include a cannula 328
having a distal cannula end, a cannula port 330 formed at its
distal end, and at least one passageway extending through at least
a distal end portion thereof in fluid communication with the
cannula port. The distal portion of the cannula may have a
preformed shape resilient curve, and may be slidably positioned
within the conduit of the support tube 322. The support tube 322
may have a longitudinal axis so that the distal portion of the
cannula is relatively aligned with respect to the longitudinal axis
of the support tube when the cannula 328 is positioned within the
support tube, and is relatively askew with respect to the
longitudinal axis of the support tube when the distal cannula end
extends beyond the distal end of the catheter body 320. A guidewire
(not shown) may be positioned within at least a portion of the
cannula passageway. When the support tube 322 and the cannula 328
are placed in a retracted position within the catheter body 320,
the distal opening of the cannula 328 within the catheter may pass
over the guidewire. The catheter body 320 may be moved relatively
proximally so the support tube 322 extends beyond the catheter body
to expose the cut-out portion 326 of the support tube. The cannula
328 within the support tube 322 may be thereafter advanced distally
in order for the preformed distal cannula portion to deflect away
from the longitudinal axis of the catheter body 320. The distal tip
of the guidewire may be thus deflected in substantially the same
direction as the distal portion of the cannula when advanced in a
relatively distal direction within the cannula 328. The proximal
tube end of the support tube may be also connected to a rotating
assembly (not shown) to rotate the support tube relative to the
catheter body. The cut-out portion 326 of the support tube 322 may
be aligned in a specific manner which guides the general direction
in which the distal cannula portion is pointed and extended outside
of the catheter.
58. Another intravascular catheter provided in accordance with the
invention is further shown in FIG. 20. The catheter may also
include a catheter body 340 formed with a distal end, a catheter
port 342, a longitudinal axis, and a longitudinal lumen formed
along at least a distal portion of the catheter body in fluid
communication with the catheter port. A cannula 348 with a distal
cannula end 344 may be slidably positioned within the longitudinal
lumen of the catheter body 340. At least one passageway may be
formed in the cannula 348 which may provide for slidable movement
of a guidewire. The passageway may be in fluid communication with a
cannula port formed at the distal end 344 of the cannula. The
distal end 344 of the cannula may further include a support tube
section 350. The support tube 350 may be formed with a distal tube
end section 352, a proximal tube end section 354, and a backbone
356 connecting the distal and the proximal tube end sections. The
backbone 356 of the support tube 350 may include a plurality of
cut-out rib sections. The removed portions of the support tube 350
may provide reduced compression and increased flexibility of the
support tube, and may support more responsive deflecting movement
of the distal cannula end 344. The support tube 350 may be also
preformed with a predetermined shape to deflect the distal cannula
end 344 away from the longitudinal axis of the catheter body 340
when the distal cannula end is extended proximally past the distal
end of the catheter body. Alternatively or additionally, the distal
cannula end 344 may be preformed with a predetermined shape that
deflects away from the longitudinal axis of the catheter body 340
end when extended past the distal end of the catheter body. The
cannula 348 may be slidably movable within the longitudinal lumen
of the catheter body 340. As with other cannulas described herein,
the proximal end of the cannula may be connected to a hub assembly
that provides or supports rotational or longitudinal movement of
the cannula in either a relatively distal or proximal movement
relative to the catheter body.
59. While all aspects of the present invention have been described
with reference to the aforementioned applications, this description
of various embodiments and methods shall not be construed in a
limiting sense. The aforementioned is presented for purposes of
illustration and complete description that are consistent with all
applicable standards. It shall be understood that all aspects of
the invention are not limited to the specific depictions,
configurations or relative proportions set forth herein which
depend upon a variety of conditions and variables. The
specification is not intended to be exhaustive or to limit the
invention to the precise forms disclosed herein. Various
modifications and insubstantial changes in form and detail of the
particular embodiments of the disclosed invention, as well as other
variations of the invention, will be apparent to a person skilled
in the art upon reference to the present disclosure. It is
therefore contemplated that the appended claims shall cover any
such modifications, variations or equivalents as to the described
embodiments as falling within the true spirit and scope of the
invention.
* * * * *