U.S. patent application number 11/775819 was filed with the patent office on 2008-01-17 for methods and apparatus for treatment of atrial fibrillation.
This patent application is currently assigned to Voyage Medical, Inc.. Invention is credited to Ruey-Feng Peh, Chris A. Rothe, Vahid Saadat, Edmund A. Tam.
Application Number | 20080015569 11/775819 |
Document ID | / |
Family ID | 46328986 |
Filed Date | 2008-01-17 |
United States Patent
Application |
20080015569 |
Kind Code |
A1 |
Saadat; Vahid ; et
al. |
January 17, 2008 |
METHODS AND APPARATUS FOR TREATMENT OF ATRIAL FIBRILLATION
Abstract
Apparatus and methods for the treatment of atrial fibrillation
are described herein where tissue to be ablated may be monitored
under direct visualization. Such a system may include a deployment
catheter and an attached imaging hood deployable into an expanded
configuration. In use, the imaging hood is placed against or
adjacent to the tissue to be imaged in a body lumen that is
normally filled with an opaque bodily fluid such as blood. A
translucent or transparent fluid can be pumped into the imaging
hood until the fluid displaces any blood leaving a clear region of
tissue to be imaged via an imaging element in the deployment
catheter. An ablation probe may be advanced into the contained
region where the tissue may be ablated and monitored for changes in
color as well as appropriate positioning.
Inventors: |
Saadat; Vahid; (Saratoga,
CA) ; Peh; Ruey-Feng; (Mountain View, CA) ;
Tam; Edmund A.; (Mountain View, CA) ; Rothe; Chris
A.; (San Mateo, CA) |
Correspondence
Address: |
LEVINE BAGADE HAN LLP
2483 EAST BAYSHORE ROAD, SUITE 100
PALO ALTO
CA
94303
US
|
Assignee: |
Voyage Medical, Inc.
Campbell
CA
|
Family ID: |
46328986 |
Appl. No.: |
11/775819 |
Filed: |
July 10, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11259498 |
Oct 25, 2005 |
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11775819 |
Jul 10, 2007 |
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60806923 |
Jul 10, 2006 |
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60806924 |
Jul 10, 2006 |
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60806926 |
Jul 10, 2006 |
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60649246 |
Feb 2, 2005 |
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Current U.S.
Class: |
606/41 ; 600/104;
604/103.1; 604/529; 607/122 |
Current CPC
Class: |
A61B 5/6882 20130101;
A61B 1/04 20130101; A61B 5/0031 20130101; A61B 1/00085 20130101;
A61B 1/00082 20130101; A61B 2018/0212 20130101; A61B 1/0008
20130101; A61B 5/02007 20130101; A61B 1/015 20130101; A61B 8/12
20130101; A61B 1/00089 20130101; A61B 1/005 20130101; A61B 1/018
20130101 |
Class at
Publication: |
606/041 ;
600/104; 604/103.1; 604/529; 607/122 |
International
Class: |
A61B 18/14 20060101
A61B018/14; A61B 1/045 20060101 A61B001/045; A61M 25/00 20060101
A61M025/00 |
Claims
1. A tissue imaging and treatment system, comprising: a deployment
catheter defining at least one lumen therethrough; a barrier or
membrane projecting distally from the deployment catheter and
defining an open area therein, wherein the open area is in fluid
communication with the at least one lumen; a visualization element
disposed within or along the barrier or membrane for visualizing
tissue adjacent to the open area; and an ablation energy
transmitting surface positionable to ablate tissue adjacent to or
contained within the open area.
2. The system of claim 1 further comprising a delivery catheter
through which the deployment catheter is deliverable.
3. The system of claim 1 wherein the deployment catheter is
steerable.
4. The system of claim 3 wherein the deployment catheter is steered
via pulling at least one wire.
5. The system of claim 3 wherein the deployment catheter is steered
via computer control.
6. The system of claim 1 wherein the barrier or membrane is
comprised of a compliant material.
7. The system of claim 1 wherein the barrier or membrane defines a
peripheral contact edge for placement against a tissue surface so
that the tissue surface spans along and within the contact edge,
wherein the energy transmitting surface comprises an electrode
electrically coupleable to the tissue surface span for ablating the
visualized tissue.
8. The system of claim 1 wherein the barrier or membrane is adapted
to be reconfigured from a low-profile delivery configuration to an
expanded deployed configuration.
9. The system of claim 8 wherein the barrier or membrane is adapted
to self-expand into the expanded deployed configuration.
10. The system of claim 8 wherein the barrier or membrane comprises
one or more support struts along the barrier or membrane.
11. The system of claim 1 wherein the barrier or membrane is
conically shaped.
12. The system of claim 1 wherein the visualization element
comprises at least one optical fiber, CCD imager, or CMOS
imager.
13. The system of claim 1 wherein the visualization element is
disposed within a distal end of the deployment catheter.
14. The system of claim 1 wherein the visualization element is
articulatable off-axis relative to a longitudinal axis of the
deployment catheter.
15. The system of claim 1 further comprising a fluid reservoir
fluidly coupled to the barrier or membrane.
16. The system of claim 15 wherein the fluid comprises saline,
plasma, water, or perfluorinated liquid.
17. The system of claim 1 wherein the barrier or membrane further
comprises a distal membrane extending over the open area such that
the energy transmitting surface comprises an ablation electrode
circumferentially disposed over the distal membrane.
18. The system of claim 1 wherein the barrier or membrane further
comprises a distal membrane extending radially inwardly near a
distal edge of the barrier or membrane partially over the open area
such that the distal membrane defines an aperture through which the
ablation electrode is extendable.
19. The system of claim 1 wherein the energy transmitting surface
comprises an ablation electrode, and wherein the ablation electrode
is articulatable.
20. The system of claim 1 wherein the energy transmitting surface
comprises an ablation electrode, and wherein the ablation electrode
comprises a monopolar or bipolar radio-frequency electrode.
21. The system of claim 1 wherein the energy transmitting surface
is reconfigurable from a first linear profile to a second extended
profile.
22. The system of claim 21 wherein the second extended profile
defines a linear configuration transverse relative to a
longitudinal axis of the deployment catheter.
23. The system of claim 21 wherein the energy transmitting surface
is contained within a linear housing which is articulatable between
a linear profile and an expanded Y-shaped profile.
24. The system of claim 21 wherein the second extended profile
defines a circular configuration.
25. The system of claim 1 wherein the energy transmitting surface
is circumferentially disposed over a contact lip or edge of the
barrier or membrane.
26. The system of claim 1 wherein the ablation probe comprises a
plurality of needles.
27. The system of claim 26 wherein the plurality of needles is
extendable from a retracted configuration into an ablation
configuration.
28. The system of claim 1 further comprising an occlusion balloon
which is expandable into an inflated shape sufficiently sized to
occlude a vessel lumen.
29. The system of claim 1 further comprising a first articulatable
tissue grasper positioned upon a first support member extending
distally from the barrier or membrane.
30. The system of claim 29 further comprising a second
articulatable tissue grasper positioned upon a second support
member extending distally from the barrier or membrane, wherein the
second tissue grasper is articulatable independently of the first
tissue grasper.
31. The system of claim 29 further comprising a length of wire or
suture slidably passed through the tissue grasper, wherein a first
end of the wire or suture is attached to the tissue imaging and
treatment system and a second end of the wire or suture is pulled
from outside a patient body.
32. The system of claim 1 further comprising an intra-atrial
balloon disposed upon a distal end of the catheter, wherein the
balloon is expandable from a low-profile deflated configuration to
an inflated configuration.
33. The system of claim 32 wherein the inflated configuration
occupies up to 75% or more of volume of an atrial chamber within a
patient heart.
34. The system of claim 32 wherein the intra-atrial balloon
comprises one or more radio-opaque markers.
35. A tissue imaging and treatment system for treating a tissue
region within a heart, the heart having a chamber, the chamber
including a tissue surface and containing blood, the system
comprising: a catheter body having a lumen; a visualization element
disposed adjacent the catheter body, the visualization element
having a field of view; a translucent fluid source in fluid
communication with the lumen; and a barrier or membrane extendable
from the catheter body to localize, between the visualization
element and the field of view, displacement of blood by translucent
fluid that flows from the lumen; and an ablation energy
transmitting surface positionable for ablating the tissue within
the field of view.
36. The system of claim 35 wherein the membrane or barrier is
disposed about an open area between the visualization element and
the field of view, the fluid source configured to inject
translucent fluid so as to displace the blood from the open area
sufficiently to allow optical imaging of the tissue surface though
the open area while the heart is beating.
37. The system of claim 36 wherein the membrane is expandable from
a low-profile delivery configuration to an expanded configuration
to encompass an imaged tissue surface larger than a cross-section
of the catheter.
38. The system of claim 37 further comprises a frame supporting the
membrane outside of the open area in the expanded
configuration.
39. The system of claim 38 wherein the frame comprises a shape
memory alloy, and wherein the visualization element is supported by
the frame.
40. The system of claim 35 wherein the barrier or membrane
comprises a hood, the barrier or membrane having a contact edge
surrounding an aperture adjacent the field of view so that, during
use, transparent fluid from the lumen is released into the chamber
of the heart through the aperture, wherein the energy transmitting
surface is translatable through the aperture.
41. The system of claim 35 wherein the barrier or membrane has an
inner surface and an outer surface, a volume disposed within the
inner surface being greater than a volume disposed between the
inner surface and the outer surface.
42. The system of claim 35 wherein the catheter body is included in
a steerable catheter, the steerable catheter having an elongate
proximal portion and an articulable section adjacent the barrier,
the steerable section comprising a plurality of links and steerable
from a proximal end of the proximal portion so as to impose a
smooth axial curvature on the catheter body.
43. The system of claim 35 wherein the catheter body has a working
lumen slidably receiving the energy transmitting surface, a lumen
for receiving a steering element to laterally deflect the catheter
body, a translucent fluid flow lumen, and an image conduit for
transmitting images of the tissue surface from the visualization
element.
44. The system of claim 35 wherein the barrier or membrane further
comprises a distal membrane extending partially over the open area
such that the distal membrane defines an aperture through which the
energy transmitting surface is extendable.
45. The system of claim 35 wherein the energy transmitting surface
comprises an articulatable ablation electrode.
46. The system of claim 35 wherein the energy transmitting surface
comprises a monopolar or bipolar radio-frequency electrode.
47. The system of claim 35 wherein the energy transmitting surface
comprises a plurality of needles.
48. The system of claim. 47 wherein the plurality of needles is
extendable from a retracted configuration into an ablation
configuration.
49. The system of claim 35 further comprising an occlusion balloon
which is expandable into an inflated shape sufficiently sized to
occlude a vessel lumen.
50. The system of claim 35 further comprising a first articulatable
tissue grasper positioned upon a first support member extending
distally from the barrier or membrane.
51. The system of claim 50 further comprising a second
articulatable tissue grasper positioned upon a second support
member extending distally from the barrier or membrane, wherein the
second tissue grasper is articulatable independently of the first
tissue grasper.
52. The system of claim 50 further comprising a length of wire or
suture slidably passed through the tissue grasper, wherein a first
end of the wire or suture is attached to the tissue imaging and
treatment system and a second end of the wire or suture is pulled
from outside a patient body.
53. A method for intravascularly treating a tissue region within a
body lumen, comprising: positioning an open area of a barrier or
membrane against or adjacent to the tissue region to be treated;
displacing an opaque bodily fluid with a translucent fluid from an
open area defined by the barrier or membrane and the tissue region;
visualizing the tissue region within the open area through the
translucent fluid; and ablating at least a portion of the tissue
region within the open area.
54. The method of claim 53 wherein positioning an open area of a
barrier or membrane comprises advancing the barrier or membrane
into a left atrial chamber of a heart.
55. The method of claim 53 wherein positioning an open area of a
barrier or membrane comprises deploying the barrier or membrane
from a low-profile delivery configuration into an expanded deployed
configuration.
56. The method of claim 53 wherein positioning an open area of a
barrier or membrane comprises stabilizing a position of the barrier
or membrane relative to the tissue region.
57. The method of claim 53 wherein positioning an open area of a
barrier or membrane comprises steering the deployment catheter to
the tissue region.
58. The method of claim 53 wherein displacing an opaque bodily
fluid with a translucent fluid comprises infusing the translucent
fluid into the open area through a fluid delivery lumen defined
through the deployment catheter.
59. The method of claim 58 wherein infusing the translucent fluid
comprises pumping saline, plasma, water, or perfluorinated liquid
into the open area such that blood is displaced from therefrom.
60. The method of claim 53 wherein displacing an opaque bodily
fluid with a translucent fluid comprises partially retaining the
fluid within the open area via at least one transparent distal
membrane disposed at least partially over a distal end of the
barrier or membrane.
61. The method of claim 60 wherein partially retaining the fluid
comprises allowing the fluid to leak through at least one aperture
defined through the distal membrane.
62. The method of claim 61 wherein ablating comprises ablating the
tissue region through the at least one aperture.
63. The method of claim 53 wherein visualizing the region of tissue
comprises viewing the tissue via an imaging element positioned
off-axis relative to a longitudinal axis of the barrier or
membrane.
64. The method of claim 53 wherein ablating comprises contacting
the tissue region with an ablation probe advanced through the open
area.
65. The method of claim 64 further comprising articulating the
ablation probe within the open area.
66. The method of claim 53 wherein ablating comprises forming a
linear or circular lesion upon the tissue region.
67. The method of claim 53 further comprising occluding a blood
flow through a pulmonary vein via an occlusion balloon inflated
within the pulmonary vein distal to the barrier or membrane prior
to ablating.
68. The method of claim 53 further comprising temporarily engaging
a first and second tissue region in an alternating manner such that
the barrier or membrane is moved from a first location to a second
location through the body lumen prior to displacing an opaque
bodily fluid.
69. The method of claim 53 wherein ablating comprises advancing a
plurality of ablation needles into the tissue region.
70. The method of claim 53 further comprising visually monitoring
the tissue region for changes in color while ablating as an
indication of sufficient tissue ablation.
71. The method of claim 53 further comprising visually monitoring
the tissue region for indications of endocardiac disruptions.
72. The method of claim 71 wherein if an endocardiac disruption is
detected, adjusting a power of an ablation probe or ceasing
ablating the tissue region.
73. The method of claim 72 further comprising further visually
inspecting the tissue region.
74. The method of claim 71 wherein if an endocardiac disruption
occurs, containing any tissue debris released from the disruption
within the barrier or membrane.
75. The method of claim 74 further comprising suctioning the tissue
debris contained within the barrier or membrane proximally through
the deployment catheter.
76. The method of claim 53 further comprising drawing the tissue
region within the open area at least partially into the barrier or
membrane to create a seal between therebetween.
77. The method of claim 76 wherein ablating comprises ablating the
sealed tissue region within the open area.
78. The method of claim 53 further comprising visually inspecting a
lesion formed upon the tissue region within the open area.
79. The method of claim 78 further comprising repositioning the
barrier or membrane upon a second tissue region to treated.
80. A method for treating a target tissue of a heart of a patient,
the target tissue underlying an intracardiac heart tissue surface
region within a chamber of the heart, the method comprising:
optically imaging the tissue surface region; ablating the target
tissue; and monitoring tissue response to the ablation using the
optical imaging while the heart is pumping blood.
81. The method of claim 80 the heart of the patient having an
arrhythmia, wherein the optical imaging provides a system user
sufficient feedback to verify coupling between an energy
transmitting surface and the tissue surface region during formation
of an ablation lesion such that the lesion inhibits the
arrhythmia.
82. The method of claim 81 wherein the energy delivery surface
comprises an electrode surface, and wherein the system user can
induce movement of the electrode surface or interrupts lesion
formation in response to loss of contact between the target tissue
and the electrode surface during formation of the lesion.
83. The method of claim 81 wherein the optical imaging feedback
provided to the system user during formation of the lesion
comprises changes in color along the tissue surface region,
lesion-formation induced deformation along the tissue surface
region, vaporization adjacent the tissue surface region, formation
of bubbles adjacent the tissue surface region, positioning of the
energy transmitting surface, movement of the energy transmitting
surface, and/or ablation debris.
84. The method of claim 80 the heart of the patient having an
arrhythmia, wherein the target tissue comprises an elongate lesion
pattern, and wherein the optical imaging provides a system user
sufficient feedback to verify contiguity along a length of the
lesion pattern such that the lesion pattern inhibits propagation of
the arrhythmia.
85. The method of claim 84 wherein the lesion pattern comprises a
plurality of discrete ablation lesions formed sequentially in the
target tissue, and wherein a movement of an energy transmitting
surface from alignment with a first portion of the target tissue to
a second portion of the target tissue is performed using optical
feedback from the tissue response along a first discrete lesion
associated with the first region of the target tissue.
86. The method of claim 84 wherein the lesion pattern is formed by
moving an energy transmitting surface relative to the tissue
surface region while transmitting energy from the energy
transmitting surface to the target tissue, and wherein the movement
is performed using optical feedback on progress of the tissue
response along the length of the lesion pattern.
87. The method of claim 84 wherein the optical imaging feedback
provided to the system user during formation of the lesion
comprises changes in color along the tissue surface region,
lesion-formation induced deformation along the tissue surface
region, vaporization adjacent the tissue surface region, formation
of bubbles adjacent the tissue surface region, positioning of the
energy transmitting surface, movement of the energy transmitting
surface, and/or ablation debris.
88. The method of claim 80 further comprising interrupting the
ablating of the target tissue during the ablation in response to
optical indicia of a potential tissue surface disruption, wherein
the ablation is interrupted prior to embolization of ablation
debris or bursting along the tissue surface region.
89. The method of claim 81 further comprising cooling the imaged
tissue surface region during the imaging and the ablation.
90. The method of claim 80 wherein the tissue surface region is
imaged by locally displacing blood from an imaging volume within
the chamber of the heart.
91. The method of claim 90 wherein the translucent fluid comprises
a transparent fluid, wherein the chamber of the heart pumps blood
disposed around the imaging volume, and wherein-the transparent
fluid is in contact with the tissue surface region.
92. The method of claim 91 wherein the transparent fluid flows
along the tissue surface region so as to purge blood from between
the energy transmitting surface and the tissue surface region.
93. The method of claim 92 wherein the transparent fluid cools the
tissue surface region.
94. The method of claim 91 further comprising introducing a barrier
or membrane into the chamber, expanding the barrier or membrane
within the chamber, and limiting intrusion of the blood from within
the chamber into the imaging volume with the barrier or membrane
during the imaging.
95. The method of claim 80 wherein the optical imaging is performed
so as to image a plurality of anatomical landmarks, and further
comprising aligning the energy delivery surface with the target
tissue in response to an image of one or more of the imaged
landmarks.
96. The method of claim 80 wherein the anatomical landmarks
comprise a pulmonary vein, an ostium of the pulmonary vein, a left
atrial septum, a left atrial appendage, a mitral valve, a tricuspid
valve, a fossa ovalis and a right atrial appendage.
97. A system for treating a target tissue of the heart of a
patient, the target tissue underlying an intracardiac heart tissue
surface region within a chamber of the heart, the method
comprising: an intracardiac catheter having a proximal end, a
distal end, and at least one lumen; an optical imaging element
advanceable distally using the catheter into the chamber of the
heart; an energy transmitting surface advanceable distally using
the catheter into alignment with the tissue surface region for
ablation of the target tissue; and an imaging fluid flow path
extendable distally from a translucent fluid source, through the
catheter, and toward the tissue surface region, the extended flow
path encompassing the optical imaging element and the aligned
energy transmitting surface so as to inhibiting persistence of
blood within a field of view of the imaging element when optically
directing the ablation while the heart is pumping the blood.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority to the
following U.S. Prov. Pat. App. Ser. Nos. 60/806,923; 60/806,924;
and 60/806,926 each filed Jul. 10, 2006; this is also a
continuation-in-part of U.S. patent application Ser. No. 11/259,498
filed Oct. 25, 2005, which claims priority to U.S. Prov. Pat. App.
Ser. No. 60/649,246 filed Feb. 2, 2005. Each application is
incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to medical devices
used for accessing, visualizing, and/or treating regions of tissue
within a body. More particularly, the present invention relates to
methods and apparatus for accessing, visualizing, and/or treating
conditions such as atrial fibrillation within a patient heart.
BACKGROUND OF THE INVENTION
[0003] Conventional devices for visualizing interior regions of a
body lumen are known. For example, ultrasound devices have been
used to produce images from within a body in vivo. Ultrasound has
been used both with and without contrast agents, which typically
enhance ultrasound-derived images.
[0004] Other conventional methods have utilized catheters or probes
having position sensors deployed within the body lumen, such as the
interior of a cardiac chamber. These types of positional sensors
are typically used to determine the movement of a cardiac tissue
surface or the electrical activity within the cardiac tissue. When
a sufficient number of points have been sampled by the sensors, a
"map" of the cardiac tissue may be generated.
[0005] Another conventional device utilizes an inflatable balloon
which is typically introduced intravascularly in a deflated state
and then inflated against the tissue region to be examined. Imaging
is typically accomplished by an optical fiber or other apparatus
such as electronic chips for viewing the tissue through the
membrane(s) of the inflated balloon. Moreover, the balloon must
generally be inflated for imaging. Other conventional balloons
utilize a cavity or depression formed at a distal end of the
inflated balloon. This cavity or depression is pressed against the
tissue to be examined and is flushed with a clear fluid to provide
a clear pathway through the blood.
[0006] However, such imaging balloons have many inherent
disadvantages. For instance, such balloons generally require that
the balloon be inflated to a relatively large size which may
undesirably displace surrounding tissue and interfere with fine
positioning of the imaging system against the tissue. Moreover, the
working area created by such inflatable balloons are generally
cramped and limited in size. Furthermore, inflated balloons may be
susceptible to pressure changes in the surrounding fluid. For
example, if the environment surrounding the inflated balloon
undergoes pressure changes, e.g., during systolic and diastolic
pressure cycles in a beating heart, the constant pressure change
may affect the inflated balloon volume and its positioning to
produce unsteady or undesirable conditions for optimal tissue
imaging.
[0007] Accordingly, these types of imaging modalities are generally
unable to provide desirable images useful for sufficient diagnosis
and therapy of the endoluminal structure, due in part to factors
such as dynamic forces generated by the natural movement of the
heart. Moreover, anatomic structures within the body can occlude or
obstruct the image acquisition process. Also, the presence and
movement of opaque bodily fluids such as blood generally make in
vivo imaging of tissue regions within the heart difficult.
[0008] Other external imaging modalities are also conventionally
utilized. For example, computed tomography (CT) and magnetic
resonance imaging (MRI) are typical modalities which are widely
used to obtain images of body lumens such as the interior chambers
of the heart. However, such imaging modalities fail to provide
real-time imaging for intra-operative therapeutic procedures.
Fluoroscopic imaging, for instance, is widely used to identify
anatomic landmarks within the heart and other regions of the body.
However, fluoroscopy fails to provide an accurate image of the
tissue quality or surface and also fails to provide for
instrumentation for performing tissue manipulation or other
therapeutic procedures upon the visualized tissue regions. In
addition, fluoroscopy provides a shadow of the intervening tissue
onto a plate or sensor when it may be desirable to view the
intraluminal surface of the tissue to diagnose pathologies or to
perform some form of therapy on it.
[0009] Thus, a tissue imaging system which is able to provide
real-time in vivo images of tissue regions within body lumens such
as the heart through opaque media such as blood and which also
provide instruments for therapeutic procedures upon the visualized
tissue are desirable.
BRIEF SUMMARY OF THE INVENTION
[0010] A tissue imaging and manipulation apparatus that may be
utilized for procedures within a body lumen, such as the heart, in
which visualization of the surrounding tissue is made difficult, if
not impossible, by medium contained within the lumen such as blood,
is described below. Generally, such a tissue imaging and
manipulation apparatus comprises an optional delivery catheter or
sheath through which a deployment catheter and imaging hood may be
advanced for placement against or adjacent to the tissue to be
imaged.
[0011] The deployment catheter may define a fluid delivery lumen
therethrough as well as an imaging lumen within which an optical
imaging fiber or assembly may be disposed for imaging tissue. When
deployed, the imaging hood may be expanded into any number of
shapes, e.g., cylindrical, conical as shown, semi-spherical, etc.,
provided that an open area or field is defined by the imaging hood.
The open area is the area within which the tissue region of
interest may be imaged. The imaging hood may also define an
atraumatic contact lip or edge for placement or abutment against
the tissue region of interest. Moreover, the distal end of the
deployment catheter or separate manipulatable catheters may be
articulated through various controlling mechanisms such as
push-pull wires manually or via computer control
[0012] The deployment catheter may also be stabilized relative to
the tissue surface through various methods. For instance,
inflatable stabilizing balloons positioned along a length of the
catheter may be utilized, or tissue engagement anchors may be
passed through or along the deployment catheter for temporary
engagement of the underlying tissue.
[0013] In operation, after the imaging hood has been deployed,
fluid may be pumped at a positive pressure through the fluid
delivery lumen until the fluid fills the open area completely and
displaces any blood from within the open area. The fluid may
comprise any biocompatible fluid, e.g., saline, water, plasma,
Fluorinert.TM., etc., which is sufficiently transparent to allow
for relatively undistorted visualization through the fluid. The
fluid may be pumped continuously or intermittently to allow for
image capture by an optional processor which may be in
communication with the assembly.
[0014] In an exemplary variation for imaging tissue surfaces within
a heart chamber containing blood, the tissue imaging and treatment
system may generally comprise a catheter body having a lumen
defined therethrough, a visualization element disposed adjacent the
catheter body, the visualization element having a field of view, a
transparent fluid source in fluid communication with the lumen, and
a barrier or membrane extendable from the catheter body to
localize, between the visualization element and the field of view,
displacement of blood by transparent fluid that flows from the
lumen, and a piercing instrument translatable through the displaced
blood for piercing into the tissue surface within the field of
view.
[0015] The imaging hood may be formed into any number of
configurations and the imaging assembly may also be utilized with
any number of therapeutic tools which may be deployed through the
deployment catheter.
[0016] More particularly in certain variations, the tissue
visualization system may comprise components including the imaging
hood, where the hood may further include a membrane having a main
aperture and additional optional openings disposed over the distal
end of the hood. An introducer sheath or the deployment catheter
upon which the imaging hood is disposed may further comprise a
steerable segment made of multiple adjacent links which are
pivotably connected to one another and which may be articulated
within a single plane or multiple planes. The deployment catheter
itself may be comprised of a multiple lumen extrusion, such as a
four-lumen catheter extrusion, which is reinforced with braided
stainless steel fibers to provide structural support. The proximal
end of the catheter may be coupled to a handle for manipulation and
articulation of the system.
[0017] In additional variations of the imaging hood and deployment
catheter, the various assemblies may be configured in particular
for treating conditions such as atrial fibrillation while under
direct visualization. In particular, the devices and assemblies may
be configured to facilitate the application of energy to the
underlying tissue in a controlled manner while directly visualizing
the tissue to monitor as well as confirm appropriate treatment.
Generally, the imaging and manipulation assembly may be advanced
intravascularly into the patient's heart, e.g., through the
inferior vena cava and into the right atrium where the hood maybe
deployed and positioned against the atrial septum and the hood may
be infused with saline to clear the blood from within to view the
underlying tissue surface.
[0018] Once the hood has been desirably positioned over the fossa
ovalis, a piercing instrument, e.g., a hollow needle, may be
advanced from the catheter and through the hood to pierce through
the atrial septum until the left atrium has been accessed. A
guidewire may then be advanced through the piercing instrument and
introduced into the left atrium, where it may be further advanced
into one of the pulmonary veins. With the guidewire crossing the
atrial septum into the left atrium, the piercing instrument may be
withdrawn or the hood may be further retracted into its low profile
configuration and the catheter and sheath may be optionally
withdrawn as well while leaving the guidewire in place crossing the
atrial septum. A dilator may be advanced along the guidewire to
dilate the opening through the atrial septum to provide a larger
transseptal opening for the introduction of the hood and other
instruments into the left atrium. Further examples of methods and
devices for transseptal access are shown and described in further
detail in commonly owned U.S. patent application Ser. No.
11/763,399 filed Jun. 14, 2007, which is incorporated herein by
reference in its entirety. Those transseptal access methods and
devices may be fully utilized with the methods and devices
described herein, as practicable.
[0019] With the hood advanced into and expanded within the left
atrium, the deployment catheter and/or hood may be articulated to
be placed into contact with or over the ostia of the pulmonary
veins. Once the hood has been desirably positioned along the tissue
surrounding the pulmonary veins, the open area within the hood may
be cleared of blood with the translucent or transparent fluid for
directly visualizing the underlying tissue such that the tissue may
be ablated. An ablation probe, which may be configured in a number
of different shapes, may be advanced into and through the hood
interior while under direct visualization and brought into contact
against the tissue region of interest for ablation treatment. One
or more of the ostia may be ablated either partially or entirely
around the opening to create a conduction block. In performing the
ablation, the hood may be pressed against the tissue utilizing the
steering and/or articulation capabilities of the deployment
catheter as well as the sheath. Alternatively and/or additionally,
a negative pressure may be created within the hood by drawing in
the transparent fluid back through the deployment catheter to
create a seal with respect to the tissue surface. Moreover, the
hood may be further approximated against the tissue by utilizing
one or more tissue graspers which may be advanced through the hood,
such as helical tissue graspers, to temporarily adhere onto the
tissue and create a counter-traction force.
[0020] Because the hood allows for direct visualization of the
underlying tissue in vivo, the hood may be used to visually confirm
that the appropriate regions of tissue have been ablated and/or
that the tissue has been sufficiently ablated. Visual monitoring
and confirmation may be accomplished in real-time during a
procedure or after the procedure has been completed. Additionally,
the hood may be utilized post-operatively to image tissue which has
been ablated in a previous procedure to determine whether
appropriate tissue ablation had been accomplished.
[0021] Generally, in ablating the underlying visualized tissue with
the ablation probe, one or more ostia of the pulmonary veins or
other tissue regions within the left atrium may be ablated by
moving the ablation probe within the area defined by the hood
and/or moving the hood itself to tissue regions to be treated, such
as around the pulmonary vein ostium. Visual monitoring of the
ablation procedure not only provides real-time visual feedback to
maintain the probe-to-tissue contact, but also provides real-time
color feedback of the ablated tissue surface as an indicator when
irreversible tissue damage may occur. This color change during
lesion formation may be correlated to parameters such as impedance,
time of ablation, power applied, etc.
[0022] Moreover, real-time visual feedback also enables the user to
precisely position and move the ablation probe to desired locations
along the tissue surface fore creating precise lesion patterns.
Additionally, the visual feedback also provides a safety mechanism
by which the user can visually detect endocardial disruptions
and/or complications, such as steam formation or bubble formation.
In the event that an endocardial disruption or complication occurs,
any resulting tissue debris can be contained within the hood and
removed from the body by suctioning the contents of the hood
proximally into the deployment catheter before the debris is
released into the body. The hood also provides a relatively
isolated environment with little or no blood so as to reduce any
risk of coagulation. The displacement fluid may also provide a
cooling mechanism for the tissue surface to prevent over-heating by
introducing and purging the saline into and through the hood.
[0023] Once the ablation procedure is finished, the hood may be
utilized to visually evaluate the post-ablation lesion for
contiguous lesion formation and/or for visual confirmation of any
endocardial disruptions by identifying cratering or coagulated
tissue or charred tissue. If determined desirable or necessary upon
visual inspection, the tissue area around the pulmonary vein ostium
or other tissue region may be ablated again without having to
withdraw or re-introduce the ablation instrument.
[0024] To ablate the tissue visualized within hood, a number of
various ablation instruments may be utilized. For example, ablation
probe having at least one ablation electrode utilizing, e.g.,
radio-frequency (RF), microwave, ultrasound, laser, cryo-ablation,
etc., may be advanced through deployment catheter and into the open
area of the hood. Alternatively, variously configured ablation
probes may be utilized, such as linear or circularly-configured
ablation probes depending upon the desired lesion pattern and the
region of tissue to be ablated. Moreover, the ablation electrodes
may be placed upon the various regions of the hood as well.
[0025] Ablation treatment under direct visualization may also be
accomplished utilizing alternative visualization catheters which
may additionally provide for stability of the catheter with respect
to the dynamically moving tissue and blood flow. For example, one
or more grasping support members may be passed through the catheter
and deployed from the hood to allow for the hood to be walked or
moved along the tissue surfaces of the heart chambers. Other
variations may also utilize intra-atrial balloons which occupy a
relatively large volume of the left atrium and provide direct
visualization of the tissue surfaces.
[0026] A number of safety mechanisms may also be utilized. For
instance, to prevent the inadvertent piercing or ablation of an
ablation instrument from injuring adjacent tissue structures, such
as the esophagus, a light source or ultrasound transducer may be
attached to or through a catheter which can be inserted transorally
into the esophagus and advanced until the catheter light source is
positioned proximate to or adjacent to the heart. During an
intravascular ablation procedure in the left atrium, the operator
may utilize the imaging element to visually (or otherwise such as
through ultrasound) detect the light source in the form of a
background glow behind the tissue to be ablated as an indication of
the location of the esophagus. Another safety measure which may be
utilized during tissue ablation is the utilization of color changes
in the tissue being ablated. One particular advantage of a direct
visualization system described herein is the ability to view and
monitor the tissue in real-time and in detailed color.
[0027] The devices and methods described herein provide a number of
advantages over previous devices. For instance, ablating the
pulmonary vein ostia and/or endocardiac tissue under direct
visualization provides real-time visual feedback on contact between
the ablation probe and the tissue surface as well as visual
feedback on the precise position and movement of the ablation probe
to create desired lesion patterns.
[0028] Real-time visual feedback is also provided for confirming a
position of the hood within the atrial chamber itself by
visualizing anatomical landmarks, such as a location of a pulmonary
vein ostium or a left atrial appendage, a left atrial septum,
etc.
[0029] Real-time visual feedback is further provided for the early
detection of endocardiac disruptions and/or complications, such as
visual detection of steam or bubble formation. Real-time visual
feedback is additionally provided for color feedback of the ablated
endocardiac tissue as an indicator when irreversible tissue damage
occurs by enabling the detection of changes in the tissue
color.
[0030] Moreover, the hood itself provides a relatively isolated
environment with little or no blood so as to reduce any risk of
coagulation. The displacement fluid may also provide a cooling
mechanism for the tissue surface to prevent over-heating.
[0031] Once the ablation is completed, direct visualization further
provides the capability for visually inspecting for contiguous
lesion formation as well as inspecting color differences of the
tissue surface. Also, visual inspection of endocardiac disruptions
and/or complications is possible, for example, inspecting the
ablated tissue for visual confirmation for the presence of tissue
craters or coagulated blood on the tissue.
[0032] If endocardiac disruptions and/or complications are
detected, the hood also provides a barrier or membrane for
containing the disruption and rapidly evacuating any tissue debris.
Moreover, the hood provides for the establishment of stable contact
with the ostium of the pulmonary vein or other targeted tissue, for
example, by the creation of negative pressure within the space
defined within the hood for drawing in or suctioning the tissue to
be ablated against the hood for secure contact.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1A shows a side view of one variation of a tissue
imaging apparatus during deployment from a sheath or delivery
catheter.
[0034] FIG. 1B shows the deployed tissue imaging apparatus of FIG.
1A having an optionally expandable hood or sheath attached to an
imaging and/or diagnostic catheter.
[0035] FIG. 1C shows an end view of a deployed imaging
apparatus.
[0036] FIGS. 1D to 1F show the apparatus of FIGS. 1A to 1C with an
additional lumen, e.g., for passage of a guidewire
therethrough.
[0037] FIGS. 2A and 2B show one example of a deployed tissue imager
positioned against or adjacent to the tissue to be imaged and a
flow of fluid, such as saline, displacing blood from within the
expandable hood.
[0038] FIG. 3A shows an articulatable imaging assembly which may be
manipulated via push-pull wires or by computer control.
[0039] FIGS. 3B and 3C show steerable instruments, respectively,
where an articulatable delivery catheter may be steered within the
imaging hood or a distal portion of the deployment catheter itself
may be steered.
[0040] FIGS. 4A to 4C show side and cross-sectional end views,
respectively, of another variation having an off-axis imaging
capability.
[0041] FIG. 5 shows an illustrative view of an example of a tissue
imager advanced intravascularly within a heart for imaging tissue
regions within an atrial chamber.
[0042] FIGS. 6A to 6C illustrate deployment catheters having one or
more optional inflatable balloons or anchors for stabilizing the
device during a procedure.
[0043] FIGS. 7A and 7B illustrate a variation of an anchoring
mechanism such as a helical tissue piercing device for temporarily
stabilizing the imaging hood relative to a tissue surface.
[0044] FIG. 7C shows another variation for anchoring the imaging
hood having one or more tubular support members integrated with the
imaging hood; each support members may define a lumen therethrough
for advancing a helical tissue anchor within.
[0045] FIG. 8A shows an illustrative example of one variation of
how a tissue imager may be utilized with an imaging device.
[0046] FIG. 8B shows a further illustration of a hand-held
variation of the fluid delivery and tissue manipulation system.
[0047] FIGS. 9A to 9C illustrate an example of capturing several
images of the tissue at multiple regions.
[0048] FIGS. 10A and 10B show charts illustrating how fluid
pressure within the imaging hood may be coordinated with the
surrounding blood pressure; the fluid pressure in the imaging hood
may be coordinated with the blood pressure or it may be regulated
based upon pressure feedback from the blood.
[0049] FIG. 11A shows a side view of another variation of a tissue
imager having an imaging balloon within an expandable hood.
[0050] FIG. 11B shows another variation of a tissue imager
utilizing a translucent or transparent imaging balloon.
[0051] FIG. 12A shows another variation in which a flexible
expandable or distensible membrane may be incorporated within the
imaging hood to alter the volume of fluid dispensed.
[0052] FIGS. 12B and 12C show another variation in which the
imaging hood may be partially or selectively deployed from the
catheter to alter the area of the tissue being visualized as well
as the volume of the dispensed fluid.
[0053] FIGS. 13A and 13B show exemplary side and cross-sectional
views, respectively, of another variation in which the injected
fluid may be drawn back into the device for minimizing fluid input
into a body being treated.
[0054] FIGS. 14A to 14D show various configurations and methods for
configuring an imaging hood into a low-profile for delivery and/or
deployment.
[0055] FIGS. 15A and 15B show an imaging hood having an helically
expanding frame or support.
[0056] FIGS. 16A and 16B show another imaging hood having one or
more hood support members, which are pivotably attached at their
proximal ends to deployment catheter, integrated with a hood
membrane.
[0057] FIGS. 17A and 17B show yet another variation of the imaging
hood having at least two or more longitudinally positioned support
members supporting the imaging hood membrane where the support
members are movable relative to one another via a torquing or
pulling or pushing force.
[0058] FIGS. 18A and 18B show another variation where a distal
portion of the deployment catheter may have several pivoting
members which form a tubular shape in its low profile
configuration.
[0059] FIGS. 19A and 19B show another variation where the distal
portion of deployment catheter may be fabricated from a flexible
metallic or polymeric material to form a radially expanding
hood.
[0060] FIGS. 20A and 20B show another variation where the imaging
hood may be formed from a plurality of overlapping hood members
which overlie one another in an overlapping pattern.
[0061] FIGS. 21A and 21B show another example of an expandable hood
which is highly conformable against tissue anatomy with varying
geography.
[0062] FIG. 22A shows yet another example of an expandable hood
having a number of optional electrodes placed about the contact
edge or lip of the hood for sensing tissue contact or detecting
arrhythmias.
[0063] FIG. 22B shows another variation for conforming the imaging
hood against the underlying tissue where an inflatable contact edge
may be disposed around the circumference of the imaging hood.
[0064] FIG. 23 shows a variation of the system which may be
instrumented with a transducer for detecting the presence of blood
seeping back into the imaging hood.
[0065] FIGS. 24A and 24B show variations of the imaging hood
instrumented with sensors for detecting various physical
parameters; the sensors may be instrumented around the outer
surface of the imaging hood and also within the imaging hood.
[0066] FIGS. 25A and 25B show a variation where the imaging hood
may have one or more LEDs over the hood itself for providing
illumination of the tissue to be visualized.
[0067] FIGS. 26A and 26B show another variation in which a separate
illumination tool having one or more LEDs mounted thereon may be
utilized within the imaging hood.
[0068] FIG. 27 shows one example of how a therapeutic tool may be
advanced through the tissue imager for treating a tissue region of
interest.
[0069] FIG. 28 shows another example of a helical therapeutic tool
for treating the tissue region of interest.
[0070] FIG. 29 shows a variation of how a therapeutic tool may be
utilized with an expandable imaging balloon.
[0071] FIGS. 30A and 30B show alternative configurations for
therapeutic instruments which may be utilized; one variation is
shown having an angled instrument arm and another variation is
shown with an off-axis instrument arm.
[0072] FIGS. 31A to 31C show side and end views, respectively, of
an imaging system which may be utilized with an ablation probe.
[0073] FIGS. 32A and 32B show side and end views, respectively, of
another variation of the imaging hood with an ablation probe, where
the imaging hood may be enclosed for regulating a temperature of
the underlying tissue.
[0074] FIGS. 33A and 33B show an example in which the imaging fluid
itself may be altered in temperature to facilitate various
procedures upon the underlying tissue.
[0075] FIGS. 34A and 34B show an example of a laser ring generator
which may be utilized with the imaging system and an example for
applying the laser ring generator within the left atrium of a heart
for treating atrial fibrillation.
[0076] FIGS. 35A to 35C show an example of an extendible cannula
generally comprising an elongate tubular member which may be
positioned within the deployment catheter during delivery and then
projected distally through the imaging hood and optionally
beyond.
[0077] FIGS. 36A and 36B show side and end views, respectively, of
an imaging hood having one or more tubular support members
integrated with the hood for passing instruments or tools
therethrough for treatment upon the underlying tissue.
[0078] FIGS. 37A and 37B illustrate how an imaging device may be
guided within a heart chamber to a region of interest utilizing a
lighted probe positioned temporarily within, e.g., a lumen of the
coronary sinus.
[0079] FIGS. 38A and 38B show an imaging hood having a removable
disk-shaped member for implantation upon the tissue surface.
[0080] FIGS. 39A to 39C show one method for implanting the
removable disk of FIGS. 38A and 38B.
[0081] FIGS. 40A and 40B illustrate an imaging hood having a
deployable anchor assembly attached to the tissue contact edge and
an assembly view of the anchors and the suture or wire connected to
the anchors, respectively
[0082] FIGS. 41A to 41D show one method for deploying the anchor
assembly of FIGS. 40A and 40B for closing an opening or wound.
[0083] FIG. 42 shows another variation in which the imaging system
may be fluidly coupled to a dialysis unit for filtering a patient's
blood.
[0084] FIGS. 43A and 43B show a variation of the deployment
catheter having a first deployable hood and a second deployable
hood positioned distal to the first hood; the deployment catheter
may also have a side-viewing imaging element positioned between the
first and second hoods for imaging tissue between the expanded
hoods.
[0085] FIGS. 44A and 44B show side and end views, respectively, of
a deployment catheter having a side-imaging balloon in an
un-inflated low-profile configuration.
[0086] FIGS. 45A to 45C show side, top, and end views,
respectively, of the inflated balloon of FIGS. 44A and 44B defining
a visualization field in the inflated balloon.
[0087] FIGS. 46A and 46B show side and cross-sectional end views,
respectively, for one method of use in visualizing a lesion upon a
vessel wall within the visualization field of the inflated balloon
from FIGS. 45A to 45C.
[0088] FIGS. 47A to 470 illustrate an example for intravascularly
advancing the imaging and manipulation catheter into the heart and
into the left atrium for ablating tissue around the ostia of the
pulmonary veins for the treatment of atrial fibrillation.
[0089] FIGS. 48A and 48B illustrate partial cross-sectional views
of a hood which is advanced into the left atrium to examine
discontiguous lesions.
[0090] FIG. 49A shows a perspective view of a variation of the
transmural lesion ablation device with, in this variation, a single
RF ablation probe inserted through the working channel of the
tissue visualization catheter.
[0091] FIG. 49B shows a side view of the device performing tissue
ablation within the hood under real time visualization.
[0092] FIG. 49C shows the perspective view of the device performing
tissue ablation within the hood under real time visualization.
[0093] FIG. 50A shows a perspective view of a variation of the
device when an angled ablation probe is used for linear transmural
lesion formation.
[0094] FIG. 50B shows a perspective view of another variation of
the device when a circular ablation probe is used for circular
transmural lesion formation.
[0095] FIG. 51A shows a perspective view of another variation of
the transmural lesion ablation device with a circularly-shaped RF
electrode end effector placed on the outer circumference of an
expandable membrane covering the hood of the tissue visualization
catheter.
[0096] FIG. 51B shows a perspective view of another variation of an
expandable balloon also with a circularly-shaped RF electrode end
effector and without the hood.
[0097] FIG. 52 shows a perspective view of another variation of the
transmural lesion ablation device with RF electrodes disposed
circumferentially around the contact lip or edge of the hood.
[0098] FIGS. 53A and 53B show perspective and side views,
respectively, of another variation of the transmural lesion
ablation device with an ablation probe positioned within the hood
which also includes at least one layer of a transparent elastomeric
membrane over the distal opening of the hood.
[0099] FIG. 54A shows a perspective view of another variation of
the transmural lesion ablation device having an expandable linear
ablation electrode strip inserted through the working channel of
the tissue visualization catheter.
[0100] FIG. 54B shows the perspective view of the device with the
linear ablation electrode strip in its expanded configuration.
[0101] FIGS. 55A and 55B illustrate perspective views of another
variation where a laser probe, e.g., an optical fiber bundle
coupled to a laser generator, may be inserted through the work
channel of the tissue visualization catheter and activated for
ablation treatment.
[0102] FIG. 55C shows the device of FIGS. 55A and 55B performing
tissue ablation or transmural lesion formation under direct
visualization while working within the hood of the visualization
catheter apparatus.
[0103] FIG. 56 shows a partial cross-sectional view of the tissue
visualization catheter with an inflated occlusion balloon to
temporarily occlude blood flow through the pulmonary vein while
viewing the pulmonary vein's ostia.
[0104] FIG. 57 shows a perspective view of first and second tissue
graspers deployed through the hood for facilitating movement of the
hood along the tissue surface.
[0105] FIGS. 58A to 58C illustrate the tissue visualization
catheter navigating around a body lumen, such as the left atrium of
the heart, utilizing two tissue graspers to "walk" the catheter
along the tissue surface.
[0106] FIG. 59 shows a partial cross-sectional view of the tissue
visualization catheter in a retroflexed position for accessing the
right inferior pulmonary vein ostium.
[0107] FIG. 60 show a partial cross-sectional view of the tissue
visualization catheter intravascularly accessing the left atrium
via a trans-femoral introduction through the aorta, the aortic
valve, the left ventricle, and into the left atrium.
[0108] FIG. 61A shows a side view of the tissue visualization
catheter retroflexed at a tight angle accessing the right inferior
pulmonary vein ostium with a first tissue grasper and length of
wire or suture configured as a pulley mechanism.
[0109] FIG. 61B illustrates the tissue visualization catheter
pulling itself to access the right inferior PV ostium at a tight
angle using a suture pulley mechanism.
[0110] FIG. 61C illustrates the tissue visualization catheter prior
to the suture being tensioned.
[0111] FIG. 61D illustrates the tissue visualization catheter being
moved and approximated towards the ostium as the suture is
tensioned.
[0112] FIG. 62A shows a partial cross-sectional view of a tissue
visualization catheter having an intra-atrial balloon inflated
within the left atrium.
[0113] FIG. 62B shows the partial cross-sectional view with a
fiberscope introduced into the balloon interior.
[0114] FIG. 62C shows the partial cross-sectional view with the
fiberscope advancing and articulating within the balloon.
[0115] FIG. 62D shows the partial cross-sectional view of the
intra-atrial balloon having radio-opaque fiducial markers and an
ablation probe deployed within the balloon.
[0116] FIG. 63 shows a detail side view of an ablation probe
deployed within the balloon and penetrating through the balloon
wall.
[0117] FIGS. 64A and 64B show perspective views of ablation needles
deployable from a retracted position to a deployed position.
[0118] FIG. 64C shows the perspective view of an ablation needle
having a bipolar electrode configuration.
[0119] FIG. 65A to 65E illustrate a stabilizing catheter accessing
the left atrium with a stabilizing balloon deployed in the right
atrium and examples of the articulation and translation
capabilities for directing the hood towards the tissue region to be
treated.
[0120] FIG. 66A to 66E illustrate another variation of a
stabilizing catheter accessing the left atrium with proximal and
distal stabilizing balloons deployed about the atrial septum and
examples of the articulation and translation capabilities for
directing the hood towards the tissue region to be treated.
[0121] FIG. 67A to 67F illustrate another variation of a
stabilizing catheter accessing the left atrium with a combination
of proximal and distal stabilizing balloons deployed about the
atrial septum and an intra-atrial balloon expanded within the left
atrium with a hollow needle for piercing through the balloon and
deploying the hood external to the balloon.
[0122] FIG. 68A illustrates a side view of the tissue visualization
catheter deploying an intra-atrial balloon with an articulatable
imager capturing multiple images representing different segments of
the heart chamber wall from different angles.
[0123] FIG. 68B schematically illustrates the mapping of the
multiple captured images processed to create a panoramic visual map
of the heart chamber.
[0124] FIG. 69A shows a partial cross-sectional view of the tissue
visualization catheter in the left atrium performing RF ablation,
with a light source or ultrasound crystal source inserted
transorally into the esophagus to prevent esophageal
perforation.
[0125] FIGS. 69B and 69C illustrate the image viewed by the user
prior to the ablation probe being activated.
[0126] FIGS. 69D and 69E illustrate the image viewed by the user of
the ablated tissue changing color as the ablation probe heats the
underlying tissue.
[0127] FIGS. 69F and 69G illustrate the image viewed by the user of
an endocardiac disruption and the resulting tissue debris captured
or contained within the hood.
[0128] FIG. 69H illustrates the evacuation of the captured tissue
debris into the catheter.
[0129] FIGS. 69I to 69K illustrate one method for adhering the
tissue to be ablated via a suction force applied to the underlying
tissue to be ablated.
DETAILED DESCRIPTION OF THE INVENTION
[0130] A tissue-imaging and manipulation apparatus described below
is able to provide real-time images in vivo of tissue regions
within a body lumen such as a heart, which is filled with blood
flowing dynamically therethrough and is also able to provide
intravascular tools and instruments for performing various
procedures upon the imaged tissue regions. Such an apparatus may be
utilized for many procedures, e.g., facilitating transseptal access
to the left atrium, cannulating the coronary sinus, diagnosis of
valve regurgitation/stenosis, valvuloplasty, atrial appendage
closure, arrhythmogenic focus ablation, among other procedures.
[0131] One variation of a tissue access and imaging apparatus is
shown in the detail perspective views of FIGS. 1A to 1C. As shown
in FIG. 1A, tissue imaging and manipulation assembly 10 may be
delivered intravascularly through the patient's body in a
low-profile configuration via a delivery catheter or sheath 14. In
the case of treating tissue, such as the mitral valve located at
the outflow tract of the left atrium of the heart, it is generally
desirable to enter or access the left atrium while minimizing
trauma to the patient. To non-operatively effect such access, one
conventional approach involves puncturing the intra-atrial septum
from the right atrial chamber to the left atrial chamber in a
procedure commonly called a transseptal procedure or septostomy.
For procedures such as percutaneous valve repair and replacement,
transseptal access to the left atrial chamber of the heart may
allow for larger devices to be introduced into the venous system
than can generally be introduced percutaneously into the arterial
system.
[0132] When the imaging and manipulation assembly 10 is ready to be
utilized for imaging tissue, imaging hood 12 may be advanced
relative to catheter 14 and deployed from a distal opening of
catheter 14, as shown by the arrow. Upon deployment, imaging hood
12 may be unconstrained to expand or open into a deployed imaging
configuration, as shown in FIG. 1B. Imaging hood 12 may be
fabricated from a variety of pliable or conformable biocompatible
material including but not limited to, e.g., polymeric, plastic, or
woven materials. One example of a woven material is Kevlar.RTM.
(E.I. du Pont de Nemours, Wilmington, Del.), which is an aramid and
which can be made into thin, e.g., less than 0.001 in., materials
which maintain enough integrity for such applications described
herein. Moreover, the imaging hood 12 may be fabricated from a
translucent or opaque material and in a variety of different colors
to optimize or attenuate any reflected lighting from surrounding
fluids or structures, i.e., anatomical or mechanical structures or
instruments. In either case, imaging hood 12 may be fabricated into
a uniform structure or a scaffold-supported structure, in which
case a scaffold made of a shape memory alloy, such as Nitinol, or a
spring steel, or plastic, etc., may be fabricated and covered with
the polymeric, plastic, or woven material. Hence, imaging hood 12
may comprise any of a wide variety of barriers or membrane
structures, as may generally be used to localize displacement of
blood or the like from a selected volume of a body lumen or heart
chamber. In exemplary embodiments, a volume within an inner surface
13 of imaging hood 12 will be significantly less than a volume of
the hood 12 between inner surface 13 and outer surface 11.
[0133] Imaging hood 12 may be attached at interface 24 to a
deployment catheter 16 which may be translated independently of
deployment catheter or sheath 14. Attachment of interface 24 may be
accomplished through any number of conventional methods. Deployment
catheter 16 may define a fluid delivery lumen 18 as well as an
imaging lumen 20 within which an optical imaging fiber or assembly
may be disposed for imaging tissue. When deployed, imaging hood 12
may expand into any number of shapes, e.g., cylindrical, conical as
shown, semi-spherical, etc., provided that an open area or field 26
is defined by imaging hood 12. The open area 26 is the area within
which the tissue region of interest may be imaged. Imaging hood 12
may also define an atraumatic contact lip or edge 22 for placement
or abutment against the tissue region of interest. Moreover, the
diameter of imaging hood 12 at its maximum fully deployed diameter,
e.g., at contact lip or edge 22, is typically greater relative to a
diameter of the deployment catheter 16 (although a diameter of
contact lip or edge 22 may be made to have a smaller or equal
diameter of deployment catheter 16). For instance, the contact edge
diameter may range anywhere from 1 to 5 times (or even greater, as
practicable) a diameter of deployment catheter 16. FIG. 1C shows an
end view of the imaging hood 12 in its deployed configuration. Also
shown are the contact lip or edge 22 and fluid delivery lumen 18
and imaging lumen 20.
[0134] The imaging and manipulation assembly 10 may additionally
define a guidewire lumen therethrough, e.g., a concentric or
eccentric lumen, as shown in the side and end views, respectively,
of FIGS. 1D to 1F. The deployment catheter 16 may define guidewire
lumen 19 for facilitating the passage of the system over or along a
guidewire 17, which may be advanced intravascularly within a body
lumen. The deployment catheter 16 may then be advanced over the
guidewire 17, as generally known in the art.
[0135] In operation, after imaging hood 12 has been deployed, as in
FIG. 1B, and desirably positioned against the tissue region to be
imaged along contact edge 22, the displacing fluid may be pumped at
positive pressure through fluid delivery lumen 18 until the fluid
fills open area 26 completely and displaces any fluid 28 from
within open area 26. The displacing fluid flow may be laminarized
to improve its clearing effect and to help prevent blood from
re-entering the imaging hood 12. Alternatively, fluid flow may be
started before the deployment takes place. The displacing fluid,
also described herein as imaging fluid, may comprise any
biocompatible fluid, e.g., saline, water, plasma, etc., which is
sufficiently transparent to allow for relatively undistorted
visualization through the fluid. Alternatively or additionally, any
number of therapeutic drugs may be suspended within the fluid or
may comprise the fluid itself which is pumped into open area 26 and
which is subsequently passed into and through the heart and the
patient body.
[0136] As seen in the example of FIGS. 2A and 2B, deployment
catheter 16 may be manipulated to position deployed imaging hood 12
against or near the underlying tissue region of interest to be
imaged, in this example a portion of annulus A of mitral valve MV
within the left atrial chamber. As the surrounding blood 30 flows
around imaging hood 12 and within open area 26 defined within
imaging hood 12, as seen in FIG. 2A, the underlying annulus A is
obstructed by the opaque blood 30 and is difficult to view through
the imaging lumen 20. The translucent fluid 28, such as saline, may
then be pumped through fluid delivery lumen 18, intermittently or
continuously, until the blood 30 is at least partially, and
preferably completely, displaced from within open area 26 by fluid
28, as shown in FIG. 2B.
[0137] Although contact edge 22 need not directly contact the
underlying tissue, it is at least preferably brought into close
proximity to the tissue such that the flow of clear fluid 28 from
open area 26 may be maintained to inhibit significant backflow of
blood 30 back into open area 26. Contact edge 22 may also be made
of a soft elastomeric material such as certain soft grades of
silicone or polyurethane, as typically known, to help contact edge
22 conform to an uneven or rough underlying anatomical tissue
surface. Once the blood 30 has been displaced from imaging hood 12,
an image may then be viewed of the underlying tissue through the
clear fluid 30. This image may then be recorded or available for
real-time viewing for performing a therapeutic procedure. The
positive flow of fluid 28 may be maintained continuously to provide
for clear viewing of the underlying tissue. Alternatively, the
fluid 28 may be pumped temporarily or sporadically only until a
clear view of the tissue is available to be imaged and recorded, at
which point the fluid flow 28 may cease and blood 30 may be allowed
to seep or flow back into imaging hood 12. This process may be
repeated a number of times at the same tissue region or at multiple
tissue regions.
[0138] In desirably positioning the assembly at various regions
within the patient body, a number of articulation and manipulation
controls may be utilized. For example, as shown in the
articulatable imaging assembly 40 in FIG. 3A, one or more push-pull
wires 42 may be routed through deployment catheter 16 for steering
the distal end portion of the device in various directions 46 to
desirably position the imaging hood 12 adjacent to a region of
tissue to be visualized. Depending upon the positioning and the
number of push-pull wires 42 utilized, deployment catheter 16 and
imaging hood 12 may be articulated into any number of
configurations 44. The push-pull wire or wires 42 may be
articulated via their proximal ends from outside the patient body
manually utilizing one or more controls. Alternatively, deployment
catheter 16 may be articulated by computer control, as further
described below.
[0139] Additionally or alternatively, an articulatable delivery
catheter 48, which may be articulated via one or more push-pull
wires and having an imaging lumen and one or more working lumens,
may be delivered through the deployment catheter 16 and into
imaging hood 12. With a distal portion of articulatable delivery
catheter 48 within imaging hood 12, the clear displacing fluid may
be pumped through delivery catheter 48 or deployment catheter 16 to
clear the field within imaging hood 12. As shown in FIG. 3B, the
articulatable delivery catheter 48 may be articulated within the
imaging hood to obtain a better image of tissue adjacent to the
imaging hood 12. Moreover, articulatable delivery catheter 48 may
be articulated to direct an instrument or tool passed through the
catheter 48, as described in detail below, to specific areas of
tissue imaged through imaging hood 12 without having to reposition
deployment catheter 16 and re-clear the imaging field within hood
12.
[0140] Alternatively, rather than passing an articulatable delivery
catheter 48 through the deployment catheter 16, a distal portion of
the deployment catheter 16 itself may comprise a distal end 49
which is articulatable within imaging hood 12, as shown in FIG. 3C.
Directed imaging, instrument delivery, etc., may be accomplished
directly through one or more lumens within deployment catheter 16
to specific regions of the underlying tissue imaged within imaging
hood 12.
[0141] Visualization within the imaging hood 12 may be accomplished
through an imaging lumen 20 defined through deployment catheter 16,
as described above. In such a configuration, visualization is
available in a straight-line manner, i.e., images are generated
from the field distally along a longitudinal axis defined by the
deployment catheter 16. Alternatively or additionally, an
articulatable imaging assembly having a pivotable support member 50
may be connected to, mounted to, or otherwise passed through
deployment catheter 16 to provide for visualization off-axis
relative to the longitudinal axis defined by deployment catheter
16, as shown in FIG. 4A. Support member 50 may have an imaging
element 52, e.g., a CCD or CMOS imager or optical fiber, attached
at its distal end with its proximal end connected to deployment
catheter 16 via a pivoting connection 54.
[0142] If one or more optical fibers are utilized for imaging, the
optical fibers 58 may be passed through deployment catheter 16, as
shown in the cross-section of FIG. 4B, and routed through the
support member 50. The use of optical fibers 58 may provide for
increased diameter sizes of the one or several lumens 56 through
deployment catheter 16 for the passage of diagnostic and/or
therapeutic tools therethrough. Alternatively, electronic chips,
such as a charge coupled device (CCD) or a CMOS imager, which are
typically known, may be utilized in place of the optical fibers 58,
in which case the electronic imager may be positioned in the distal
portion of the deployment catheter 16 with electric wires being
routed proximally through the deployment catheter 16.
Alternatively, the electronic imagers may be wirelessly coupled to
a receiver for the wireless transmission of images. Additional
optical fibers or light emitting diodes (LEDs) can be used to
provide lighting for the image or operative theater, as described
below in further detail. Support member 50 may be pivoted via
connection 54 such that the member 50 can be positioned in a
low-profile configuration within channel or groove 60 defined in a
distal portion of catheter 16, as shown in the cross-section of
FIG. 4C. During intravascular delivery of deployment catheter 16
through the patient body, support member 50 can be positioned
within channel or groove 60 with imaging hood 12 also in its
low-profile configuration. During visualization, imaging hood 12
may be expanded into its deployed configuration and support member
50 may be deployed into its off-axis configuration for imaging the
tissue adjacent to hood 12, as in FIG. 4A. Other configurations for
support member 50 for off-axis visualization may be utilized, as
desired.
[0143] FIG. 5 shows an illustrative cross-sectional view of a heart
H having tissue regions of interest being viewed via an imaging
assembly 10. In this example, delivery catheter assembly 70 may be
introduced percutaneously into the patient's vasculature and
advanced through the superior vena cava SVC and into the right
atrium RA. The delivery catheter or sheath 72 may be articulated
through the atrial septum AS and into the left atrium LA for
viewing or treating the tissue, e.g., the annulus A, surrounding
the mitral valve MV. As shown, deployment catheter 16 and imaging
hood 12 may be advanced out of delivery catheter 72 and brought
into contact or in proximity to the tissue region of interest. In
other examples, delivery catheter assembly 70 may be advanced
through the inferior vena cava IVC, if so desired. Moreover, other
regions of the heart H, e.g., the right ventricle RV or left
ventricle LV, may also be accessed and imaged or treated by imaging
assembly 10.
[0144] In accessing regions of the heart H or other parts of the
body, the delivery catheter or sheath 14 may comprise a
conventional intra-vascular catheter or an endoluminal delivery
device. Alternatively, robotically-controlled delivery catheters
may also be optionally utilized with the imaging assembly described
herein, in which case a computer-controller 74 may be used to
control the articulation and positioning of the delivery catheter
14. An example of a robotically-controlled delivery catheter which
may be utilized is described in further detail in US Pat. Pub.
2002/0087169 A1 to Brock et al. entitled "Flexible Instrument",
which is incorporated herein by reference in its entirety. Other
robotically-controlled delivery catheters manufactured by Hansen
Medical, Inc. (Mountain View, Calif.) may also be utilized with the
delivery catheter 14.
[0145] To facilitate stabilization of the deployment catheter 16
during a procedure, one or more inflatable balloons or anchors 76
may be positioned along the length of catheter 16, as shown in FIG.
6A. For example, when utilizing a transseptal approach across the
atrial septum AS into the left atrium LA, the inflatable balloons
76 may be inflated from a low-profile into their expanded
configuration to temporarily anchor or stabilize the catheter 16
position relative to the heart H. FIG. 6B shows a first balloon 78
inflated while FIG. 6C also shows a second balloon 80 inflated
proximal to the first balloon 78. In such a configuration, the
septal wall AS may be wedged or sandwiched between the balloons 78,
80 to temporarily stabilize the catheter 16 and imaging hood 12. A
single balloon 78 or both balloons 78, 80 may be used. Other
alternatives may utilize expandable mesh members, malecots, or any
other temporary expandable structure. After a procedure has been
accomplished, the balloon assembly 76 may be deflated or
re-configured into a low-profile for removal of the deployment
catheter 16.
[0146] To further stabilize a position of the imaging hood 12
relative to a tissue surface to be imaged, various anchoring
mechanisms may be optionally employed for temporarily holding the
imaging hood 12 against the tissue. Such anchoring mechanisms may
be particularly useful for imaging tissue which is subject to
movement, e.g., when imaging tissue within the chambers of a
beating heart. A tool delivery catheter 82 having at least one
instrument lumen and an optional visualization lumen may be
delivered through deployment catheter 16 and into an expanded
imaging hood 12. As the imaging hood 12 is brought into contact
against a tissue surface T to be examined, anchoring mechanisms
such as a helical tissue piercing device 84 may be passed through
the tool delivery catheter 82, as shown in FIG. 7A, and into
imaging hood 12.
[0147] The helical tissue engaging device 84 may be torqued from
its proximal end outside the patient body to temporarily anchor
itself into the underlying tissue surface T. Once embedded within
the tissue T, the helical tissue engaging device 84 may be pulled
proximally relative to deployment catheter 16 while the deployment
catheter 16 and imaging hood 12 are pushed distally, as indicated
by the arrows in FIG. 7B, to gently force the contact edge or lip
22 of imaging hood against the tissue T. The positioning of the
tissue engaging device 84 may be locked temporarily relative to the
deployment catheter 16 to ensure secure positioning of the imaging
hood 12 during a diagnostic or therapeutic procedure within the
imaging hood 12. After a procedure, tissue engaging device 84 may
be disengaged from the tissue by torquing its proximal end in the
opposite direction to remove the anchor form the tissue T and the
deployment catheter 16 may be repositioned to another region of
tissue where the anchoring process may be repeated or removed from
the patient body. The tissue engaging device 84 may also be
constructed from other known tissue engaging devices such as
vacuum-assisted engagement or grasper-assisted engagement tools,
among others.
[0148] Although a helical anchor 84 is shown, this is intended to
be illustrative and other types of temporary anchors may be
utilized, e.g., hooked or barbed anchors, graspers, etc. Moreover,
the tool delivery catheter 82 may be omitted entirely and the
anchoring device may be delivered directly through a lumen defined
through the deployment catheter 16.
[0149] In another variation where the tool delivery catheter 82 may
be omitted entirely to temporarily anchor imaging hood 12, FIG. 7C
shows an imaging hood 12 having one or more tubular support members
86, e.g., four support members 86 as shown, integrated with the
imaging hood 12. The tubular support members 86 may define lumens
therethrough each having helical tissue engaging devices 88
positioned within. When an expanded imaging hood 12 is to be
temporarily anchored to the tissue, the helical tissue engaging
devices 88 may be urged distally to extend from imaging hood 12 and
each may be torqued from its proximal end to engage the underlying
tissue T. Each of the helical tissue engaging devices 88 may be
advanced through the length of deployment catheter 16 or they may
be positioned within tubular support members 86 during the delivery
and deployment of imaging hood 12. Once the procedure within
imaging hood 12 is finished, each of the tissue engaging devices 88
may be disengaged from the tissue and the imaging hood 12 may be
repositioned to another region of tissue or removed from the
patient body.
[0150] An illustrative example is shown in FIG. 8A of a tissue
imaging assembly connected to a fluid delivery system 90 and to an
optional processor 98 and image recorder and/or viewer 100. The
fluid delivery system 90 may generally comprise a pump 92 and an
optional valve 94 for controlling the flow rate of the fluid into
the system. A fluid reservoir 96, fluidly connected to pump 92, may
hold the fluid to be pumped through imaging hood 12. An optional
central processing unit or processor 98 may be in electrical
communication with fluid delivery system 90 for controlling flow
parameters such as the flow rate and/or velocity of the pumped
fluid. The processor 98 may also be in electrical communication
with an image recorder and/or viewer 100 for directly viewing the
images of tissue received from within imaging hood 12. Imager
recorder and/or viewer 100 may also be used not only to record the
image but also the location of the viewed tissue region, if so
desired.
[0151] Optionally, processor 98 may also be utilized to coordinate
the fluid flow and the image capture. For instance, processor 98
may be programmed to provide for fluid flow from reservoir 96 until
the tissue area has been displaced of blood to obtain a clear
image. Once the image has been determined to be sufficiently clear,
either visually by a practitioner or by computer, an image of the
tissue may be captured automatically by recorder 100 and pump 92
may be automatically stopped or slowed by processor 98 to cease the
fluid flow into the patient. Other variations for fluid delivery
and image capture are, of course, possible and the aforementioned
configuration is intended only to be illustrative and not
limiting.
[0152] FIG. 8B shows a further illustration of a hand-held
variation of the fluid delivery and tissue manipulation system 110.
In this variation, system 110 may have a housing or handle assembly
112 which can be held or manipulated by the physician from outside
the patient body. The fluid reservoir 114, shown in this variation
as a syringe, can be fluidly coupled to the handle assembly 112 and
actuated via a pumping mechanism 116, e.g., lead screw. Fluid
reservoir 114 may be a simple reservoir separated from the handle
assembly 112 and fluidly coupled to handle assembly 112 via one or
more tubes. The fluid flow rate and other mechanisms may be metered
by the electronic controller 118.
[0153] Deployment of imaging hood 12 maybe actuated by a hood
deployment switch 120 located on the handle assembly 112 while
dispensation of the fluid from reservoir 114 may be actuated by a
fluid deployment switch 122, which can be electrically coupled to
the controller 118. Controller 118 may also be electrically coupled
to a wired or wireless antenna 124 optionally integrated with the
handle assembly 112, as shown in the figure. The wireless antenna
124 can be used to wirelessly transmit images captured from the
imaging hood 12 to a receiver, e.g., via Bluetooth.RTM. wireless
technology (Bluetooth SIG, Inc., Bellevue, Wash.), RF, etc., for
viewing on a monitor 128 or for recording for later viewing.
[0154] Articulation control of the deployment catheter 16, or a
delivery catheter or sheath 14 through which the deployment
catheter 16 may be delivered, may be accomplished by computer
control, as described above, in which case an additional controller
may be utilized with handle assembly 112. In the case of manual
articulation, handle assembly 112 may incorporate one or more
articulation controls 126 for manual manipulation of the position
of deployment catheter 16. Handle assembly 112 may also define one
or more instrument ports 130 through which a number of
intravascular tools may be passed for tissue manipulation and
treatment within imaging hood 12, as described further below.
Furthermore, in certain procedures, fluid or debris may be sucked
into imaging hood 12 for evacuation from the patient body by
optionally fluidly coupling a suction pump 132 to handle assembly
112 or directly to deployment catheter 16.
[0155] As described above, fluid may be pumped continuously into
imaging hood 12 to provide for clear viewing of the underlying
tissue. Alternatively, fluid may be pumped temporarily or
sporadically only until a clear view of the tissue is available to
be imaged and recorded, at which point the fluid flow may cease and
the blood may be allowed to seep or flow back into imaging hood 12.
FIGS. 9A to 9C illustrate an example of capturing several images of
the tissue at multiple regions. Deployment catheter 16 may be
desirably positioned and imaging hood 12 deployed and brought into
position against a region of tissue to be imaged, in this example
the tissue surrounding a mitral valve MV within the left atrium of
a patient's heart. The imaging hood 12 may be optionally anchored
to the tissue, as described above, and then cleared by pumping the
imaging fluid into the hood 12. Once sufficiently clear, the tissue
may be visualized and the image captured by control electronics
118. The first captured image 140 may be stored and/or transmitted
wirelessly 124 to a monitor 128 for viewing by the physician, as
shown in FIG. 9A.
[0156] The deployment catheter 16 may be then repositioned to an
adjacent portion of mitral valve MV, as shown in FIG. 9B, where the
process may be repeated to capture a second image 142 for viewing
and/or recording. The deployment catheter 16 may again be
repositioned to another region of tissue, as shown in FIG. 9C,
where a third image 144 may be captured for viewing and/or
recording. This procedure may be repeated as many times as
necessary for capturing a comprehensive image of the tissue
surrounding mitral valve MV, or any other tissue region. When the
deployment catheter 16 and imaging hood 12 is repositioned from
tissue region to tissue region, the pump may be stopped during
positioning and blood or surrounding fluid may be allowed to enter
within imaging hood 12 until the tissue is to be imaged, where the
imaging hood 12 may be cleared, as above.
[0157] As mentioned above, when the imaging hood 12 is cleared by
pumping the imaging fluid within for clearing the blood or other
bodily fluid, the fluid may be pumped continuously to maintain the
imaging fluid within the hood 12 at a positive pressure or it may
be pumped under computer control for slowing or stopping the fluid
flow into the hood 12 upon detection of various parameters or until
a clear image of the underlying tissue is obtained. The control
electronics 118 may also be programmed to coordinate the fluid flow
into the imaging hood 12 with various physical parameters to
maintain a clear image within imaging hood 12.
[0158] One example is shown in FIG. 10A which shows a chart 150
illustrating how fluid pressure within the imaging hood 12 may be
coordinated with the surrounding blood pressure. Chart 150 shows
the cyclical blood pressure 156 alternating between diastolic
pressure 152 and systolic pressure 154 over time T due to the
beating motion of the patient heart. The fluid pressure of the
imaging fluid, indicated by plot 160, within imaging hood 12 may be
automatically timed to correspond to the blood pressure changes 160
such that an increased pressure is maintained within imaging hood
12 which is consistently above the blood pressure 156 by a slight
increase .DELTA.P, as illustrated by the pressure difference at the
peak systolic pressure 158. This pressure difference, .DELTA.P, may
be maintained within imaging hood 12 over the pressure variance of
the surrounding blood pressure to maintain a positive imaging fluid
pressure within imaging hood 12 to maintain a clear view of the
underlying tissue. One benefit of maintaining a constant .DELTA.P
is a constant flow and maintenance of a clear field.
[0159] FIG. 10B shows a chart 162 illustrating another variation
for maintaining a clear view of the underlying tissue where one or
more sensors within the imaging hood 12, as described in further
detail below, may be configured to sense pressure changes within
the imaging hood 12 and to correspondingly increase the imaging
fluid pressure within imaging hood 12. This may result in a time
delay, .DELTA.T, as illustrated by the shifted fluid pressure 160
relative to the cycling blood pressure 156, although the time
delays .DELTA.T may be negligible in maintaining the clear image of
the underlying tissue. Predictive software algorithms can also be
used to substantially eliminate this time delay by predicting when
the next pressure wave peak will arrive and by increasing the
pressure ahead of the pressure wave's arrival by an amount of time
equal to the aforementioned time delay to essentially cancel the
time delay out.
[0160] The variations in fluid pressure within imaging hood 12 may
be accomplished in part due to the nature of imaging hood 12. An
inflatable balloon, which is conventionally utilized for imaging
tissue, may be affected by the surrounding blood pressure changes.
On the other hand, an imaging hood 12 retains a constant volume
therewithin and is structurally unaffected by the surrounding blood
pressure changes, thus allowing for pressure increases therewithin.
The material that hood 12 is made from may also contribute to the
manner in which the pressure is modulated within this hood 12. A
stiffer hood material, such as high durometer polyurethane or
Nylon, may facilitate the maintaining of an open hood when
deployed. On the other hand, a relatively lower durometer or softer
material, such as a low durometer PVC or polyurethane, may collapse
from the surrounding fluid pressure and may not adequately maintain
a deployed or expanded hood.
[0161] Turning now to the imaging hood, other variations of the
tissue imaging assembly may be utilized, as shown in FIG. 11A,
which shows another variation comprising an additional imaging
balloon 172 within an imaging hood 174. In this variation, an
expandable balloon 172 having a translucent skin may be positioned
within imaging hood 174. Balloon 172 may be made from any
distensible biocompatible material having sufficient translucent
properties which allow for visualization therethrough. Once the
imaging hood 174 has been deployed against the tissue region of
interest, balloon 172 may be filled with a fluid, such as saline,
or less preferably a gas, until balloon 172 has been expanded until
the blood has been sufficiently displaced. The balloon 172 may thus
be expanded proximal to or into contact against the tissue region
to be viewed. The balloon 172 can also be filled with contrast
media to allow it to be viewed on fluoroscopy to aid in its
positioning. The imager, e.g., fiber optic, positioned within
deployment catheter 170 may then be utilized to view the tissue
region through the balloon 172 and any additional fluid which may
be pumped into imaging hood 174 via one or more optional fluid
ports 176, which may be positioned proximally of balloon 172 along
a portion of deployment catheter 170. Alternatively, balloon 172
may define one or more holes over its surface which allow for
seepage or passage of the fluid contained therein to escape and
displace the blood from within imaging hood 174.
[0162] FIG. 11B shows another alternative in which balloon 180 may
be utilized alone. Balloon 180, attached to deployment catheter
178, may be filled with fluid, such as saline or contrast media,
and is preferably allowed to come into direct contact with the
tissue region to be imaged.
[0163] FIG. 12A shows another alternative in which deployment
catheter 16 incorporates imaging hood 12, as above, and includes an
additional flexible membrane 182 within imaging hood 12. Flexible
membrane 182 may be attached at a distal end of catheter 16 and
optionally at contact edge 22. Imaging hood 12 may be utilized, as
above, and membrane 182 may be deployed from catheter 16 in vivo or
prior to placing catheter 16 within a patient to reduce the volume
within imaging hood 12. The volume may be reduced or minimized to
reduce the amount of fluid dispensed for visualization or simply
reduced depending upon the area of tissue to be visualized.
[0164] FIGS. 12B and 12C show yet another alternative in which
imaging hood 186 may be withdrawn proximally within deployment
catheter 184 or deployed distally from catheter 186, as shown, to
vary the volume of imaging hood 186 and thus the volume of
dispensed fluid. Imaging hood 186 may be seen in FIG. 12B as being
partially deployed from, e.g., a circumferentially defined lumen
within catheter 184, such as annular lumen 188. The underlying
tissue may be visualized with imaging hood 186 only partially
deployed. Alternatively, imaging hood 186' may be fully deployed,
as shown in FIG. 12C, by urging hood 186' distally out from annular
lumen 188. In this expanded configuration, the area of tissue to be
visualized may be increased as hood 186' is expanded
circumferentially.
[0165] FIGS. 13A and 13B show perspective and cross-sectional side
views, respectively, of yet another variation of imaging assembly
which may utilize a fluid suction system for minimizing the amount
of fluid injected into the patient's heart or other body lumen
during tissue visualization. Deployment catheter 190 in this
variation may define an inner tubular member 196 which may be
integrated with deployment catheter 190 or independently
translatable. Fluid delivery lumen 198 defined through member 196
may be fluidly connected to imaging hood 192, which may also define
one or more open channels 194 over its contact lip region. Fluid
pumped through fluid delivery lumen 198 may thus fill open area 202
to displace any blood or other fluids or objects therewithin. As
the clear fluid is forced out of open area 202, it may be sucked or
drawn immediately through one or more channels 194 and back into
deployment catheter 190. Tubular member 196 may also define one or
more additional working channels 200 for the passage of any tools
or visualization devices.
[0166] In deploying the imaging hood in the examples described
herein, the imaging hood may take on any number of configurations
when positioned or configured for a low-profile delivery within the
delivery catheter, as shown in the examples of FIGS. 14A to 14D.
These examples are intended to be illustrative and are not intended
to be limiting in scope. FIG. 14A shows one example in which
imaging hood 212 maybe compressed within catheter 210 by folding
hood 212 along a plurality of pleats. Hood 212 may also comprise
scaffolding or frame 214 made of a super-elastic or shape memory
material or alloy, e.g., Nitinol, Elgiloy, shape memory polymers,
electroactive polymers, or a spring stainless steel. The shape
memory material may act to expand or deploy imaging hood 212 into
its expanded configuration when urged in the direction of the arrow
from the constraints of catheter 210.
[0167] FIG. 14B shows another example in which imaging hood, 216
may be expanded or deployed from catheter 210 from a folded and
overlapping configuration. Frame or scaffolding 214 may also be
utilized in this example. FIG. 14C shows yet another example in
which imaging hood 218 may be rolled, inverted, or everted upon
itself for deployment. In yet another example, FIG. 14D shows a
configuration in which imaging hood 220 may be fabricated from an
extremely compliant material which allows for hood 220 to be simply
compressed into a low-profile shape. From this low-profile
compressed shape, simply releasing hood 220 may allow for it to
expand into its deployed configuration, especially if a scaffold or
frame of a shape memory or superelastic material, e.g., Nitinol, is
utilized in its construction.
[0168] Another variation for expanding the imaging hood is shown in
FIGS. 15A and 15B which illustrates an helically expanding frame or
support 230. In its constrained low-profile configuration, shown in
FIG. 15A, helical frame 230 may be integrated with the imaging hood
12 membrane. When free to expand, as shown in FIG. 15B, helical
frame 230 may expand into a conical or tapered shape. Helical frame
230 may alternatively be made out of heat-activated Nitinol to
allow it to expand upon application of a current.
[0169] FIGS. 16A and 16B show yet another variation in which
imaging hood 12 may comprise one or more hood support members 232
integrated with the hood membrane. These longitudinally attached
support members 232 may be pivotably attached at their proximal
ends to deployment catheter 16. One or more pullwires 234 may be
routed through the length of deployment catheter 16 and extend
through one or more openings 238 defined in deployment catheter 16
proximally to imaging hood 12 into attachment with a corresponding
support member 232 at a pullwire attachment point 236. The support
members 232 may be fabricated from a plastic or metal, such as
stainless steel. Alternatively, the support members 232 may be made
from a superelastic or shape memory alloy, such as Nitinol, which
may self-expand into its deployed configuration without the use or
need of pullwires. A heat-activated Nitinol may also be used which
expands upon the application of thermal energy or electrical
energy. In another alternative, support members 232 may also be
constructed as inflatable lumens utilizing, e.g., PET balloons.
From its low-profile delivery configuration shown in FIG. 16A, the
one or more pullwires 234 may be tensioned from their proximal ends
outside the patient body to pull a corresponding support member 232
into a deployed configuration, as shown in FIG. 16B, to expand
imaging hood 12. To reconfigure imaging hood 12 back into its low
profile, deployment catheter 16 may be pulled proximally into a
constraining catheter or the pullwires 234 may be simply pushed
distally to collapse imaging hood 12.
[0170] FIGS. 17A and 17B show yet another variation of imaging hood
240 having at least two or more longitudinally positioned support
members 242 supporting the imaging hood membrane. The support
members 242 each have cross-support members 244 which extend
diagonally between and are pivotably attached to the support
members 242. Each of the cross-support members 244 may be pivotably
attached to one another where they intersect between the support
members 242. A jack or screw member 246 maybe coupled to each
cross-support member 244 at this intersection point and a torquing
member, such as a torqueable wire 248, may be coupled to each jack
or screw member 246 and extend proximally through deployment
catheter 16 to outside the patient body. From outside the patient
body, the torqueable wires 248 may be torqued to turn the jack or
screw member 246 which in turn urges the cross-support members 244
to angle relative to one another and thereby urge the support
members 242 away from one another. Thus, the imaging hood 240 may
be transitioned from its low-profile, shown in FIG. 17A, to its
expanded profile, shown in FIG. 17B, and back into its low-profile
by torquing wires 248.
[0171] FIGS. 18A and 18B show yet another variation on the imaging
hood and its deployment. As shown, a distal portion of deployment
catheter 16 may have several pivoting members 250, e.g., two to
four sections, which form a tubular shape in its low profile
configuration, as shown in FIG. 18A. When pivoted radially about
deployment catheter 16, pivoting members 250 may open into a
deployed configuration having distensible or expanding membranes
252 extending over the gaps in-between the pivoting members 250, as
shown in FIG. 18B. The distensible membrane 252 may be attached to
the pivoting members 250 through various methods, e.g., adhesives,
such that when the pivoting members 250 are fully extended into a
conical shape, the pivoting members 250 and membrane 252 form a
conical shape for use as an imaging hood. The distensible membrane
252 may be made out of a porous material such as a mesh or PTFE or
out of a translucent or transparent polymer such as polyurethane,
PVC, Nylon, etc.
[0172] FIGS. 19A and 19B show yet another variation where the
distal portion of deployment catheter 16 may be fabricated from a
flexible metallic or polymeric material to form a radially
expanding hood 254. A plurality of slots 256 may be formed in a
uniform pattern over the distal portion of deployment catheter 16,
as shown in FIG. 19A. The slots 256 may be formed in a pattern such
that when the distal portion is urged radially open, utilizing any
of the methods described above, a radially expanded and
conically-shaped hood 254 may be formed by each of the slots 256
expanding into an opening, as shown in FIG. 19B. A distensible
membrane 258 may overlie the exterior surface or the interior
surface of the hood 254 to form a fluid-impermeable hood 254 such
that the hood 254 may be utilized as an imaging hood.
Alternatively, the distensible membrane 258 may alternatively be
formed in each opening 258 to form the fluid-impermeable hood 254.
Once the imaging procedure has been completed, hood 254 may be
retracted into its low-profile configuration.
[0173] Yet another configuration for the imaging hood may be seen
in FIGS. 20A and 20B where the imaging hood may be formed from a
plurality of overlapping hood members 260 which overlie one another
in an overlapping pattern. When expanded, each of the hood members
260 may extend radially outward relative to deployment catheter 16
to form a conically-shaped imaging hood, as shown in FIG. 20B.
Adjacent hood members 260 may overlap one another along an
overlapping interface 262 to form a fluid-retaining surface within
the imaging hood. Moreover, the hood members 260 may be made from
any number of biocompatible materials, e.g., Nitinol, stainless
steel, polymers, etc., which are sufficiently strong to optionally
retract surrounding tissue from the tissue region of interest.
[0174] Although it is generally desirable to have an imaging hood
contact against a tissue surface in a normal orientation, the
imaging hood may be alternatively configured to contact the tissue
surface at an acute angle. An imaging hood configured for such
contact against tissue may also be especially suitable for contact
against tissue surfaces having an unpredictable or uneven
anatomical geography. For instance, as shown in the variation of
FIG. 21A, deployment catheter 270 may have an imaging hood 272 that
is configured to be especially compliant. In this variation,
imaging hood 272 may be comprised of one or more sections 274 that
are configured to fold or collapse, e.g., by utilizing a pleated
surface. Thus, as shown in FIG. 21B, when imaging hood 272 is
contacted against uneven tissue surface T, sections 274 are able to
conform closely against the tissue. These sections 274 may be
individually collapsible by utilizing an accordion style
construction to allow conformation, e.g., to the trabeculae in the
heart or the uneven anatomy that may be found inside the various
body lumens.
[0175] In yet another alternative, FIG. 22A shows another variation
in which an imaging hood 282 is attached to deployment catheter
280. The contact lip or edge 284 may comprise one or more
electrical contacts 286 positioned circumferentially around contact
edge 284. The electrical contacts 286 may be configured to contact
the tissue and indicate affirmatively whether tissue contact was
achieved, e.g., by measuring the differential impedance between
blood and tissue. Alternatively, a processor, e.g., processor 98,
in electrical communication with contacts 286 may be configured to
determine what type of tissue is in contact with electrical
contacts 286. In yet another alternative, the processor 98 may be
configured to measure any electrical activity that may be occurring
in the underlying tissue, e.g., accessory pathways, for the
purposes of electrically mapping the cardiac tissue and
subsequently treating, as described below, any arrhythmias which
may be detected.
[0176] Another variation for ensuring contact between imaging hood
282 and the underlying tissue may be seen in FIG. 22B. This
variation may have an inflatable contact edge 288 around the
circumference of imaging hood 282. The inflatable contact edge 288
may be inflated with a fluid or gas through inflation lumen 289
when the imaging hood 282 is to be placed against a tissue surface
having an uneven or varied anatomy. The inflated circumferential
surface 288 may provide for continuous contact over the hood edge
by conforming against the tissue surface and facilitating imaging
fluid retention within hood 282.
[0177] Aside from the imaging hood, various instrumentation may be
utilized with the imaging and manipulation system. For instance,
after the field within imaging hood 12 has been cleared of the
opaque blood and the underlying tissue is visualized through the
clear fluid, blood may seep back into the imaging hood 12 and
obstruct the view. One method for automatically maintaining a clear
imaging field may utilize a transducer, e.g., an ultrasonic
transducer 290, positioned at the distal end of deployment catheter
within the imaging hood 12, as shown in FIG. 23. The transducer 290
may send an energy pulse 292 into the imaging hood 12 and wait to
detect back-scattered energy 294 reflected from debris or blood
within the imaging hood 12. If back-scattered energy is detected,
the pump may be actuated automatically to dispense more fluid into
the imaging hood until the debris or blood is no longer
detected.
[0178] Alternatively, one or more sensors 300 may be positioned on
the imaging hood 12 itself, as shown in FIG. 24A, to detect a
number of different parameters. For example, sensors 300 may be
configured to detect for the presence of oxygen in the surrounding
blood, blood and/or imaging fluid pressure, color of the fluid
within the imaging hood, etc. Fluid color may be particularly
useful in detecting the presence of blood within the imaging hood
12 by utilizing a reflective type sensor to detect back reflection
from blood. Any reflected light from blood which may be present
within imaging hood 12 may be optically or electrically transmitted
through deployment catheter 16 and to a red colored filter within
control electronics 118. Any red color which may be detected may
indicate the presence of blood and trigger a signal to the
physician or automatically actuate the pump to dispense more fluid
into the imaging hood 12 to clear the blood.
[0179] Alternative methods for detecting the presence of blood
within the hood 12 may include detecting transmitted light through
the imaging fluid within imaging hood 12. If a source of white
light, e.g., utilizing LEDs or optical fibers, is illuminated
inside imaging hood 12, the presence of blood may cause the color
red to be filtered through this fluid. The degree or intensity of
the red color detected may correspond to the amount of blood
present within imaging hood 12. A red color sensor can simply
comprise, in one variation, a phototransistor with a red
transmitting filter over it which can establish how much red light
is detected, which in turn can indicate the presence of blood
within imaging hood 12. Once blood is detected, the system may pump
more clearing fluid through and enable closed loop feedback control
of the clearing fluid pressure and flow level.
[0180] Any number of sensors may be positioned along the exterior
302 of imaging hood 12 or within the interior 304 of imaging hood
12 to detect parameters not only exteriorly to imaging hood 12 but
also within imaging hood 12. Such a configuration, as shown in FIG.
24B, may be particularly useful for automatically maintaining a
clear imaging field based upon physical parameters such as blood
pressure, as described above for FIGS. 10A and 10B.
[0181] Aside from sensors, one or more light emitting diodes (LEDs)
may be utilized to provide lighting within the imaging hood 12.
Although illumination may be provided by optical fibers routed
through deployment catheter 16, the use of LEDs over the imaging
hood 12 may eliminate the need for additional optical fibers for
providing illumination. The electrical wires connected to the one
or more LEDs may be routed through or over the hood 12 and along an
exterior surface or extruded within deployment catheter 16. One or
more LEDs may be positioned in a circumferential pattern 306 around
imaging hood 12, as shown in FIG. 25A, or in a linear longitudinal
pattern 308 along imaging hood 12, as shown in FIG. 25B. Other
patterns, such as a helical or spiral pattern, may also be
utilized. Alternatively, LEDs may be positioned along a support
member forming part of imaging hood 12.
[0182] In another alternative for illumination within imaging hood
12, a separate illumination tool 310 may be utilized, as shown in
FIG. 26A. An example of such a tool may comprise a flexible
intravascular delivery member 312 having a carrier member 314
pivotably connected 316 to a distal end of delivery member 312. One
or more LEDs 318 may be mounted along carrier member 314. In use,
delivery member 312 may be advanced through deployment catheter 16
until carrier member 314 is positioned within imaging hood 12. Once
within imaging hood 12, carrier member 314 may be pivoted in any
number of directions to facilitate or optimize the illumination
within the imaging hood 12, as shown in FIG. 26B.
[0183] In utilizing LEDs for illumination, whether positioned along
imaging hood 12 or along a separate instrument, the LEDs may
comprise a single LED color, e.g., white light. Alternatively, LEDs
of other colors, e.g., red, blue, yellow, etc., may be utilized
exclusively or in combination with white LEDs to provide for varied
illumination of the tissue or fluids being imaged. Alternatively,
sources of infrared or ultraviolet light may be employed to enable
imaging beneath the tissue surface or cause fluorescence of tissue
for use in system guidance, diagnosis, or therapy.
[0184] Aside from providing a visualization platform, the imaging
assembly may also be utilized to provide a therapeutic platform for
treating tissue being visualized. As shown in FIG. 27, deployment
catheter 320 may have imaging hood 322, as described above, and
fluid delivery lumen 324 and imaging lumen 326. In this variation,
a therapeutic tool such as needle 328 may be delivered through
fluid delivery lumen 324 or in another working lumen and advanced
through open area 332 for treating the tissue which is visualized.
In this instance, needle 328 may define one or several ports 330
for delivering drugs therethrough. Thus, once the appropriate
region of tissue has been imaged and located, needle 328 may be
advanced and pierced into the underlying tissue where a therapeutic
agent may be delivered through ports 330. Alternatively, needle 328
may be in electrical communication with a power source 334, e.g.,
radio-frequency, microwave, etc., for ablating the underlying
tissue area of interest.
[0185] FIG. 28 shows another alternative in which deployment
catheter 340 may have imaging hood 342 attached thereto, as above,
but with a therapeutic tool 344 in the configuration of a helical
tissue piercing device 344. Also shown and described above in FIGS.
7A and 7B for use in stabilizing the imaging hood relative to the
underlying tissue, the helical tissue piercing device 344 may also
be utilized to manipulate the tissue for a variety of therapeutic
procedures. The helical portion 346 may also define one or several
ports for delivery of therapeutic agents therethrough.
[0186] In yet another alternative, FIG. 29 shows a deployment
catheter 350 having an expandable imaging balloon 352 filled with,
e.g., saline 356. A therapeutic tool 344, as above, may be
translatable relative to balloon 352. To prevent the piercing
portion 346 of the tool from tearing balloon 352, a stop 354 may be
formed on balloon 352 to prevent the proximal passage of portion
346 past stop 354.
[0187] Alternative configurations for tools which may be delivered
through deployment catheter 16 for use in tissue manipulation
within imaging hood 12 are shown in FIGS. 30A and 30B. FIG. 30A
shows one variation of an angled instrument 360, such as a tissue
grasper, which may be configured to have an elongate shaft for
intravascular delivery through deployment catheter 16 with a distal
end which may be angled relative to its elongate shaft upon
deployment into imaging hood 12. The elongate shaft may be
configured to angle itself automatically, e.g., by the elongate
shaft being made at least partially from a shape memory alloy, or
upon actuation, e.g., by tensioning a pullwire. FIG. 30B shows
another configuration for an instrument 362 being configured to
reconfigure its distal portion into an off-axis configuration
within imaging hood 12. In either case, the instruments 360, 362
may be reconfigured into a low-profile shape upon withdrawing them
proximally back into deployment catheter 16.
[0188] Other instruments or tools which may be utilized with the
imaging system is shown in the side and end views of FIGS. 31A to
31C. FIG. 31A shows a probe 370 having a distal end effector 372,
which may be reconfigured from a low-profile shape to a curved
profile. The end effector 372 may be configured as an ablation
probe utilizing radio-frequency energy, microwave energy,
ultrasound energy, laser energy or even cryo-ablation.
Alternatively, the end effector 372 may have several electrodes
upon it for detecting or mapping electrical signals transmitted
through the underlying tissue.
[0189] In the case of an end effector 372 utilized for ablation of
the underlying tissue, an additional temperature sensor such as a
thermocouple or thermistor 374 positioned upon an elongate member
376 may be advanced into the imaging hood 12 adjacent to the distal
end effector 372 for contacting and monitoring a temperature of the
ablated tissue. FIG. 31B shows an example in the end view of one
configuration for the distal end effector 372 which may be simply
angled into a perpendicular configuration for contacting the
tissue. FIG. 31C shows another example where the end effector may
be reconfigured into a curved end effector 378 for increased tissue
contact.
[0190] FIGS. 32A and 32B show another variation of an ablation tool
utilized with an imaging hood 12 having an enclosed bottom portion.
In this variation, an ablation probe, such as a cryo-ablation probe
380 having a distal end effector 382, may be positioned through the
imaging hood 12 such that the end effector 382 is placed distally
of a transparent membrane or enclosure 384, as shown in the end
view of FIG. 32B. The shaft of probe 380 may pass through an
opening 386 defined through the membrane 384. In use, the clear
fluid may be pumped into imaging hood 12, as described above, and
the distal end effector 382 may be placed against a tissue region
to be ablated with the imaging hood 12 and the membrane 384
positioned atop or adjacent to the ablated tissue. In the case of
cryo-ablation, the imaging fluid may be warmed prior to dispensing
into the imaging hood 12 such that the tissue contacted by the
membrane 384 may be warmed during the cryo-ablation procedure. In
the case of thermal ablation, e.g., utilizing radio-frequency
energy, the fluid dispensed into the imaging hood 12 may be cooled
such that the tissue contacted by the membrane 384 and adjacent to
the ablation probe during the ablation procedure is likewise
cooled.
[0191] In either example described above, the imaging fluid may be
varied in its temperature to facilitate various procedures to be
performed upon the tissue. In other cases, the imaging fluid itself
may be altered to facilitate various procedures. For instance as
shown in FIG. 33A, a deployment catheter 16 and imaging hood 12 may
be advanced within a hollow body organ, such as a bladder filled
with urine 394, towards a lesion or tumor 392 on the bladder wall.
The imaging hood 12 may be placed entirely over the lesion 392, or
over a portion of the lesion. Once secured against the tissue wall
390, a cryo-fluid, i.e., a fluid which has been cooled to below
freezing temperatures of, e.g., water or blood, may be pumped into
the imaging hood 12 to cryo-ablate the lesion 390, as shown in FIG.
33B while avoiding the creation of ice on the instrument or surface
of tissue.
[0192] As the cryo-fluid leaks out of the imaging hood 12 and into
the organ, the fluid may be warmed naturally by the patient body
and ultimately removed. The cryo-fluid may be a colorless and
translucent fluid which enables visualization therethrough of the
underlying tissue. An example of such a fluid is Fluorinert.TM.
(3M, St. Paul, Minn.), which is a colorless and odorless
perfluorinated liquid. The use of a liquid such as Fluorinert.TM.
enables the cryo-ablation procedure without the formation of ice
within or outside of the imaging hood 12. Alternatively, rather
than utilizing cryo-ablation, hyperthermic treatments may also be
effected by heating the Fluorinert.TM. liquid to elevated
temperatures for ablating the lesion 392 within the imaging hood
12. Moreover, Fluorinert.TM. may be utilized in various other parts
of the body, such as within the heart.
[0193] FIG. 34A shows another variation of an instrument which may
be utilized with the imaging system. In this variation, a laser
ring generator 400 may be passed through the deployment catheter 16
and partially into imaging hood 12. A laser ring generator 400 is
typically used to create a circular ring of laser energy 402 for
generating a conduction block around the pulmonary veins typically
in the treatment of atrial fibrillation. The circular ring of laser
energy 402 may be generated such that a diameter of the ring 402 is
contained within a diameter of the imaging hood 12 to allow for
tissue ablation directly upon tissue being imaged. Signals which
cause atrial fibrillation typically come from the entry area of the
pulmonary veins into the left atrium and treatments may sometimes
include delivering ablation energy to the ostia of the pulmonary
veins within the atrium. The ablated areas of the tissue may
produce a circular scar which blocks the impulses for atrial
fibrillation.
[0194] When using the laser energy to ablate the tissue of the
heart, it may be generally desirable to maintain the integrity and
health of the tissue overlying the surface while ablating the
underlying tissue. This may be accomplished, for example, by
cooling the imaging fluid to a temperature below the body
temperature of the patient but which is above the freezing point of
blood (e.g., 2.degree. C. to 35.degree. C.). The cooled imaging
fluid may thus maintain the surface tissue at the cooled fluid
temperature while the deeper underlying tissue remains at the
patient body temperature. When the laser energy (or other types of
energy such as radio frequency energy, microwave energy, ultrasound
energy, etc.) irradiates the tissue, both the cooled tissue surface
as well as the deeper underlying tissue will rise in temperature
uniformly. The deeper underlying tissue, which was maintained at
the body temperature, will increase to temperatures which are
sufficiently high to destroy the underlying tissue. Meanwhile, the
temperature of the cooled surface tissue will also rise but only to
temperatures that are near body temperature or slightly above.
[0195] Accordingly, as shown in FIG. 34B, one example for treatment
may include passing deployment catheter 16 across the atrial septum
AS and into the left atrium LA of the patient's heart H. Other
methods of accessing the left atrium LA may also be utilized. The
imaging hood 12 and laser ring generator 400 may be positioned
adjacent to or over one or more of the ostium OT of the pulmonary
veins PV and the laser generator 400 may ablate the tissue around
the ostium OT with the circular ring of laser energy 402 to create
a conduction block. Once one or more of the tissue around the
ostium OT have been ablated, the imaging hood 12 may be
reconfigured into a low profile for removal from the patient heart
H.
[0196] One of the difficulties in treating tissue in or around the
ostium OT is the dynamic fluid flow of blood through the ostium OT.
The dynamic forces make cannulation or entry of the ostium OT
difficult. Thus, another variation on instruments or tools
utilizable with the imaging system is an extendible cannula 410
having a cannula lumen 412 defined therethrough, as shown in FIG.
35A. The extendible cannula 410 may generally comprise an elongate
tubular member which may be positioned within the deployment
catheter 16 during delivery and then projected distally through the
imaging hood 12 and optionally beyond, as shown in FIG. 35B.
[0197] In use, once the imaging hood 12 has been desirably
positioned relative to the tissue, e.g., as shown in FIG. 35C
outside the ostium OT of a pulmonary vein PV, the extendible
cannula 410 may be projected distally from the deployment catheter
16 while optionally imaging the tissue through the imaging hood 12,
as described above. The extendible cannula 410 may be projected
distally until its distal end is extended at least partially into
the ostium OT. Once in the ostium OT, an instrument or energy
ablation device may be extended through and out of the cannula
lumen 412 for treatment within the ostium OT. Upon completion of
the procedure, the cannula 410 may be withdrawn proximally and
removed from the patient body. The extendible cannula 410 may also
include an inflatable occlusion balloon at or near its distal end
to block the blood flow out of the PV to maintain a clear view of
the tissue region. Alternatively, the extendible cannula 410 may
define a lumen therethrough beyond the occlusion balloon to bypass
at least a portion of the blood that normally exits the pulmonary
vein PV by directing the blood through the cannula 410 to exit
proximal of the imaging hood.
[0198] Yet another variation for tool or instrument use may be seen
in the side and end views of FIG. 36A and 36B. In this variation,
imaging hood 12 may have one or more tubular support members 420
integrated with the hood 12. Each of the tubular support members
420 may define an access lumen 422 through which one or more
instruments or tools may be delivered for treatment upon the
underlying tissue. One particular example is shown and described
above for FIG. 7C.
[0199] Various methods and instruments may be utilized for using or
facilitating the use of the system. For instance, one method may
include facilitating the initial delivery and placement of a device
into the patient's heart. In initially guiding the imaging assembly
within the heart chamber to, e.g., the mitral valve MV, a separate
guiding probe 430 may be utilized, as shown in FIGS. 37A and 37B.
Guiding probe 430 may, for example, comprise an optical fiber
through which a light source 434 may be used to illuminate a distal
tip portion 432. The tip portion 432 may be advanced into the heart
through, e.g., the coronary sinus CS, until the tip is positioned
adjacent to the mitral valve MV. The tip 432 may be illuminated, as
shown in FIG. 37A, and imaging assembly 10 may then be guided
towards the illuminated tip 432, which is visible from within the
atrial chamber, towards mitral valve MV.
[0200] Aside from the devices and methods described above, the
imaging system may be utilized to facilitate various other
procedures. Turning now to FIGS. 38A and 38B, the imaging hood of
the device in particular may be utilized. In this example, a
collapsible membrane or disk-shaped member 440 may be temporarily
secured around the contact edge or lip of imaging hood 12. During
intravascular delivery, the imaging hood 12 and the attached member
440 may both be in a collapsed configuration to maintain a low
profile for delivery. Upon deployment, both the imaging hood 12 and
the member 440 may extend into their expanded configurations.
[0201] The disk-shaped member 440 may be comprised of a variety of
materials depending upon the application. For instance, member 440
may be fabricated from a porous polymeric material infused with a
drug eluting medicament 442 for implantation against a tissue
surface for slow infusion of the medicament into the underlying
tissue. Alternatively, the member 440 may be fabricated from a
non-porous material, e.g., metal or polymer, for implantation and
closure of a wound or over a cavity to prevent fluid leakage. In
yet another alternative, the member 440 may be made from a
distensible material which is secured to imaging hood 12 in an
expanded condition. Once implanted or secured on a tissue surface
or wound, the expanded member 440 may be released from imaging hood
12. Upon release, the expanded member 440 may shrink to a smaller
size while approximating the attached underlying tissue, e.g., to
close a wound or opening.
[0202] One method for securing the disk-shaped member 440 to a
tissue surface may include a plurality of tissue anchors 444, e.g.,
barbs, hooks, projections, etc., which are attached to a surface of
the member 440. Other methods of attachments may include adhesives,
suturing, etc. In use, as shown in FIGS. 39A to 39C, the imaging
hood 12 may be deployed in its expanded configuration with member
440 attached thereto with the plurality of tissue anchors 444
projecting distally. The tissue anchors 444 may be urged into a
tissue region to be treated 446, as seen in FIG. 39A, until the
anchors 444 are secured in the tissue and member 440 is positioned
directly against the tissue, as shown in FIG. 39B. A pullwire may
be actuated to release the member 440 from the imaging hood 12 and
deployment catheter 16 may be withdrawn proximally to leave member
440 secured against the tissue 446.
[0203] Another variation for tissue manipulation and treatment may
be seen in the variation of FIG. 40A, which illustrates an imaging
hood 12 having a deployable anchor assembly 450 attached to the
tissue contact edge 22. FIG. 40B illustrates the anchor assembly
450 detached from the imaging hood 12 for clarity. The anchor
assembly 450 may be seen as having a plurality of discrete tissue
anchors 456, e.g., barbs, hooks, projections, etc., each having a
suture retaining end, e.g., an eyelet or opening 458 in a proximal
end of the anchors 456. A suture member or wire 452 may be
slidingly connected to each anchor 456 through the openings 458 and
through a cinching element 454, which may be configured to slide
uni-directionally over the suture or wire 452 to approximate each
of the anchors 456 towards one another. Each of the anchors 456 may
be temporarily attached to the imaging hood 12 through a variety of
methods. For instance, a pullwire or retaining wire may hold each
of the anchors within a receiving ring around the circumference of
the imaging hood 12. When the anchors 456 are released, the
pullwire or retaining wire may be tensioned from its proximal end
outside the patient body to thereby free the anchors 456 from the
imaging hood 12.
[0204] One example for use of the anchor assembly 450 is shown in
FIGS. 41A to 41D for closure of an opening or wound 460, e.g.,
patent foramen ovale (PFO). The deployment catheter 16 and imaging
hood 12 may be delivered intravascularly into, e.g., a patient
heart. As the imaging hood 12 is deployed into its expanded
configuration, the imaging hood 12 may be positioned adjacent to
the opening or wound 460, as shown in FIG. 41A. With the anchor
assembly 450 positioned upon the expanded imaging hood 12,
deployment catheter 16 may be directed to urge the contact edge of
imaging hood 12 and anchor assembly 450 into the region surrounding
the tissue opening 460, as shown in FIG. 41B. Once the anchor
assembly 450 has been secured within the surrounding tissue, the
anchors may be released from imaging hood 12 leaving the anchor
assembly 450 and suture member 452 trailing from the anchors, as
shown in FIG. 41C. The suture or wire member 452 may be tightened
by pulling it proximally from outside the patient body to
approximate the anchors of anchor assembly 450 towards one another
in a purse-string manner to close the tissue opening 462, as shown
in FIG. 41D. The cinching element 454 may also be pushed distally
over the suture or wire member 452 to prevent the approximated
anchor assembly 450 from loosening or widening.
[0205] Another example for an alternative use is shown in FIG. 42,
where the deployment catheter 16 and deployed imaging hood 12 may
be positioned within a patient body for drawing blood 472 into
deployment catheter 16. The drawn blood 472 may be pumped through a
dialysis unit 470 located externally of the patient body for
filtering the drawn blood 472 and the filtered blood may be
reintroduced back into the patient.
[0206] Yet another variation is shown in FIGS. 43A and 43B, which
show a variation of the deployment catheter 480 having a first
deployable hood 482 and a second deployable hood 484 positioned
distal to the first hood 482. The deployment catheter 480 may also
have a side-viewing imaging element 486 positioned between the
first and second hoods 482, 484 along the length of the deployment
catheter 480. In use, such a device may be introduced through a
lumen 488 of a vessel VS, where one or both hoods 482, 484 may be
expanded to gently contact the surrounding walls of vessel VS. Once
hoods 482, 484 have been expanded, the clear imaging fluid may be
pumped in the space defined between the hoods 482, 484 to displace
any blood and to create an imaging space 490, as shown in FIG. 43B.
With the clear fluid in-between hoods 482, 484, the imaging element
486 may be used to view the surrounding tissue surface contained
between hoods 482, 484. Other instruments or tools may be passed
through deployment catheter 480 and through one or more openings
defined along the catheter 480 for additionally performing
therapeutic procedures upon the vessel wall.
[0207] Another variation of a deployment catheter 500 which may be
used for imaging tissue to the side of the instrument may be seen
in FIGS. 44A to 45B. FIGS. 44A and 44B show side and end views of
deployment catheter 500 having a side-imaging balloon 502 in an
un-inflated low-profile configuration. A side-imaging element 504
may be positioned within a distal portion of the catheter 500 where
the balloon 502 is disposed. When balloon 502 is inflated, it may
expand radially to contact the surrounding tissue, but where the
imaging element 504 is located, a visualization field 506 may be
created by the balloon 502, as shown in the side, top, and end
views of FIGS. 45A to 45B, respectively. The visualization field
506 may simply be a cavity or channel which is defined within the
inflated balloon 502 such that the visualization element 504 is
provided an image of the area within field 506 which is clear and
unobstructed by balloon 502.
[0208] In use, deployment catheter 500 may be advanced
intravascularly through vessel lumen 488 towards a lesion or tumor
508 to be visualized and/or treated. Upon reaching the lesion 508,
deployment catheter 500 may be positioned adjacently to the lesion
508 and balloon 502 may be inflated such that the lesion 508 is
contained within the visualization field 506. Once balloon 502 is
fully inflated and in contact against the vessel wall, clear fluid
may be pumped into visualization field 506 through deployment
catheter 500 to displace any blood or opaque fluids from the field
506, as shown in the side and end views of FIGS. 46A and 46B,
respectively. The lesion 508 may then be visually inspected and
treated by passing any number of instruments through deployment
catheter 500 and into field 506.
[0209] In additional variations of the imaging hood and deployment
catheter, the various assemblies may be configured in particular
for treating conditions such as atrial fibrillation while under
direct visualization. In particular, the devices and assemblies may
be configured to facilitate the application of energy to the
underlying tissue in a controlled manner while directly visualizing
the tissue to monitor as well as confirm appropriate treatment.
Generally, as illustrated in FIGS. 47A to 470, the imaging and
manipulation assembly may be advanced intravascularly into the
patient's heart H, e.g., through the inferior vena cava IVC and
into the right atrium RA, as shown in FIGS. 47A and 47B. Within the
right atrium RA (or prior to entering), hood 12 may be deployed and
positioned against the atrial septum AS and the hood 12 may be
infused with saline to clear the blood from within to view the
underlying tissue surface, as described above. Hood 12 may be
further manipulated or articulated into a desirable location along
the tissue wall, e.g., over the fossa ovalis FO, for puncturing
through to the left atrium LA, as shown in FIG. 47C.
[0210] Once the hood 12 has been desirably positioned over the
fossa ovalis FO, a piercing instrument 510, e.g., a hollow needle,
may be advanced from catheter 16 and through hood 12 to pierce
through the atrial septum AS until the left atrium LA has been
accessed, as shown in FIG. 47D. A guidewire 17 may then be advanced
through the piercing instrument 510 and introduced into the left
atrium LA, where it may be further advanced into one of the
pulmonary veins PV, as shown in FIG. 47E. With the guidewire 17
crossing the atrial septum AS into the left atrium LA, the piercing
instrument 510 may be withdrawn, as shown in FIG. 47F, or the hood
12 may be further retracted into its low profile configuration and
catheter 16 and sheath 14 may be optionally withdrawn as well while
leaving the guidewire 17 in place crossing the atrial septum AS, as
shown in FIG. 47G.
[0211] Although one example is illustrated for crossing through the
septal wall while under direct visualization, alternative methods
and devices for transseptal access are shown and described in
further detail in commonly owned U.S. patent application Ser. No.
11/763,399 filed Jun. 14, 2007, which is incorporated herein by
reference in its entirety. Those transseptal access methods and
devices may be fully utilized with the methods and devices
described herein, as practicable.
[0212] If sheath 14 is left in place within the inferior vena cava
IVC, an optional dilator 512 may be advanced through sheath 14 and
along guidewire 17, as shown in FIG. 47H, where it may be used to
dilate the transseptal puncture through the atrial septum AS to
allow for other instruments to be advanced transseptally into the
left atrium LA, as shown in FIG. 47I. With the transseptal opening
dilated, hood 12 in its low profile configuration and catheter 16
may be re-introduced through sheath 16 over guidewire 17 and
advanced transseptally into the left atrium LA, as shown in FIG.
47J. Optionally, guidewire 17 may be withdrawn prior to or after
introduction of hood 12 into the left atrium LA. With hood 12
advanced into and expanded within the left atrium LA, as shown in
FIG. 47K, deployment catheter 16 and/or hood 12 may be articulated
to be placed into contact with or over the ostia of the pulmonary
veins PV, as shown in FIG. 47L. Once hood 12 has been desirably
positioned along the tissue surrounding the pulmonary veins, the
open area within hood 12 may be cleared of blood with the
translucent or transparent fluid for directly visualizing the
underlying tissue such that the tissue may be ablated, as indicated
by the circumferentially ablated tissue 514 about the ostium of the
pulmonary veins shown in FIG. 47M. One or more of the ostia may be
ablated either partially or entirely around the opening to create a
conduction block, as shown respectively in FIGS. 47N and 47O.
[0213] Because the hood 12 allows for direct visualization of the
underlying tissue in vivo, hood 12 may be used to visually confirm
that the appropriate regions of tissue have been ablated and/or
that the tissue has been sufficiently ablated. Visual monitoring
and confirmation may be accomplished in real-time during a
procedure or after the procedure has been completed. Additionally,
hood 12 may be utilized post-operatively to image tissue which has
been ablated in a previous procedure to determine whether
appropriate tissue ablation had been accomplished. In the partial
cross-sectional views of FIGS. 48A and 48B, hood 12 is shown
advanced into the left atrium LA to examine discontiguous lesions
520 which have been made around an ostium of a pulmonary vein PV.
If desired or determined to be necessary, the untreated tissue may
be further ablated under direct visualization utilizing hood
12.
[0214] To ablate the tissue visualized within hood 12, a number of
various ablation instruments may be utilized. In particular, an
ablation probe 534 having at least one ablation electrode 536
utilizing, e.g., radio-frequency (RF), microwave, ultrasound,
laser, cryo-ablation, etc., may be advanced through deployment
catheter 16 and into the open area 26 of hood 12, as shown in the
perspective view of FIG. 49A. Hood 12 is also shown with several
support struts 530 extending longitudinally along hood 12 to
provide structural support as well as to provide a platform upon
which imaging element 532 may be positioned. As described above,
imaging element 532 may comprise a number of imaging devices, such
as optical fibers or electronic imagers such as CCD or CMOS
imagining elements. In either case, imaging element 532 may be
positioned along a support strut 530 off-axis relative to a
longitudinal axis of catheter 16 such that element 532 is angled to
provide a visual field of the underlying tissue and ablation probe
536. Moreover, the distal portion of ablation probe 536 may be
configured to be angled or articulatable such that probe 536 may be
positioned off-axis relative to the longitudinal axis of catheter
16 to allow for probe 536 to reach over the area of tissue
visualized within open field 26 and to also allow for a variety of
lesion patterns depending upon the desired treatment.
[0215] FIGS. 49B and 49C show side and perspective views,
respectively, of hood 12 placed against a tissue region T to be
treated where the translucent or transparent displacing fluid 538
is injected into the open area 26 of hood 12 to displace the blood
therewithin. While under direct visualization from imaging element
532, the blood may be displaced with the clear fluid to allow for
inspection of the tissue T, whereupon ablation probe 536 may be
activated and/or optionally angled to contact the underlying tissue
for treatment.
[0216] FIG. 50A shows a perspective view of a variation of the
ablation probe where a distal end effector 542 of the probe 540 may
be angled along pivoting hinge 544 from a longitudinal low-profile
configuration to a right-angled straight electrode to provide for
linear transmural lesions. Probe 540 is similarly configured to the
variation shown in FIGS. 31A and 31B above. Utilizing this
configuration, an entire line of tissue can be ablated
simultaneously rather than a spot of tissue being ablated. FIG. 50B
shows another variation where an ablation probe 546 may be
configured to have a circularly-shaped ablation end effector 548
which circumscribes the opening of hood 12. This particular
variation is also similarly configured to the variation shown above
in FIG. 31C. The diameter of the probe 548 may be varied and other
circular or elliptical configurations, as well as partially
circular configurations, may be utilized to provide for the
ablation of an entire ring of tissue.
[0217] While ablating the tissue, the saline flow from the hood 12
can be controlled such that the saline is injected over the heated
electrodes after every ablation process to cool the electrodes.
This is a safety measure which may be optionally implemented to
prevent a heated electrode from undesirably ablating other regions
of the tissue inadvertently.
[0218] In yet another variation for ablating underlying tissue
while under direct visualization, FIG. 51A shows an embodiment of
hood 12 having an expandable distal membrane 550 covering the open
area of hood 12. A circularly-shaped RF electrode end effector 552
having electrodes 554 spaced between insulating sections 556 may be
coated or otherwise disposed, e.g., by chemical vapor deposition or
any other suitable process, circumferentially around the expandable
distal membrane 550. The electrode end effector 552 may be
energized by an external power source which is in electrical
communication by wires 558. Moreover, electrode end effector 552
may be retractable into the work channels of deployment catheter
16. Imaging element 532 may be attached to a support strut of the
hood 12 to provide the visualization during the ablation process,
as described above, for viewing through the clear fluid infused
within hood 12. FIG. 51B shows a similar variation where an
inflatable balloon 560 is utilized and hood 12 has been omitted
entirely. In this case, electrode end effector 552 may be disposed
circumferentially over the balloon distal end in a similar
manner.
[0219] In either variation, circular transmural lesions may be
created by inflating infusing saline into hood 12 to extend
membrane 550 or directly into balloon 560 such that pressure may be
exerted upon the contacted target tissue, such as the pulmonary
ostia area, by the end effector 552 which may then be energized to
channel energy to the ablated tissue for lesion formation. The
amount of power delivered to each electrode end effector 552 can be
varied and controlled to enable the operator to ablate areas where
different segments of the tissue may have different thicknesses,
hence requiring different amounts of power to create a lesion.
[0220] FIG. 52 illustrates a perspective view of another variation
having a circularly-shaped electrode end effector 570 with
electrodes 572 spaced between insulating sections 574 and disposed
circumferentially around the contact lip or edge of hood 12. This
variation is similar to the configuration shown above in FIG. 22A.
Although described above for electrode mapping of the underlying
tissue, electrode end effector 570 in this variation may be
utilized to contact the tissue and to create circularly-shaped
lesions around the target tissue.
[0221] In utilizing the imaging hood 12 in any one of the
procedures described herein, the hood 12 may have an open field
which is uncovered and clear to provide direct tissue contact
between the hood interior and the underlying tissue to effect any
number of treatments upon the tissue, as described above. Yet in
additional variations, imaging hood 12 may utilize other
configurations, as also described above. An additional variation of
the imaging hood 12 is shown in the perspective and side views,
respectively, of FIGS. 53A and 53B, where imaging hood 12 includes
at least one layer of a transparent elastomeric membrane 580 over
the distal opening of hood 12. An aperture 582 having a diameter
which is less than a diameter of the outer lip of imaging hood 12
may be defined over the center of membrane 580 where a longitudinal
axis of the hood intersects the membrane such that the interior of
hood 12 remains open and in fluid communication with the
environment external to hood 12. Furthermore, aperture 582 may be
sized, e.g., between 1 to 2 mm or more in diameter and membrane 580
be made from any number of transparent elastomers such as silicone,
polyurethane, latex, etc. such that contacted tissue may also be
visualized through membrane 580 as well as through aperture
582.
[0222] Aperture 582 may function generally as a restricting
passageway to reduce the rate of fluid out-flow from the hood 12
when the interior of the hood 12 is infused with the clear fluid
through which underlying tissue regions may be visualized. Aside
from restricting out-flow of clear fluid from within hood 12,
aperture 582 may also restrict external surrounding fluids from
entering hood 12 too rapidly. The reduction in the rate of fluid
out-flow from the hood and blood in-flow into the hood may improve
visualization conditions as hood 12 may be more readily filled with
transparent fluid rather than being filled by opaque blood which
may obstruct direct visualization by the visualization
instruments.
[0223] Moreover, aperture 582 may be aligned with catheter 16 such
that any instruments (e.g., piercing instruments, guidewires,
tissue engagers, etc.) that are advanced into the hood interior may
directly access the underlying tissue uninhibited or unrestricted
for treatment through aperture 582. In other variations wherein
aperture 582 may not be aligned with catheter 16, instruments
passed through catheter 16 may still access the underlying tissue
by simply piercing through membrane 580.
[0224] FIG. 54A shows yet another variation where a single RF
ablation probe 590 may be inserted through the work channel of the
tissue visualization catheter in its closed configuration where a
first half 592 and a second half 594 are closed with respect to one
another. Upon actuation, such as by pull wires, first half 592 and
second half 594 may open up laterally via a hinged pivot 602 into a
"Y" configuration to expose an ablation electrode strip 596
connected at attachment points 598, 600 to halves 592, 594,
respectively and as shown in the perspective view of FIG. 54B.
Tension is created along the axis of the electrode strip 596 to
maintain its linear configuration. Linear transmural lesion
ablation may be then accomplished by channeling energy from the RF
electrode to the target tissue surface in contact while visualized
within hood 12.
[0225] FIGS. 55A and 55B illustrate perspective views of another
variation where a laser probe 610, e.g., an optical fiber bundle
coupled to a laser generator, may be inserted through the work
channel of the tissue visualization catheter. When actuated, laser
energy 612 may be channeled through probe 610 and applied to the
underlying tissue T at different angles 612' to form a variety of
lesion patterns, as shown in FIG. 55C.
[0226] When treating the tissue in vivo around the ostium OT of a
pulmonary vein for atrial fibrillation, occluding the blood flow
through the pulmonary veins PV may facilitate the visualization and
stabilization of hood 12 with respect to the tissue, particularly
when applying ablation energy. In one variation, with hood 12
expanded within the left atrium LA, guidewire 17 may be advanced
into the pulmonary vein PV to be treated. An expandable occlusion
balloon 620, either advanced over guidewire 17 or carried directly
upon guidewire 17, may be advanced into the pulmonary vein PV
distal to the region of tissue to be treated where it may then be
expanded into contact with the walls of the pulmonary vein PV, as
shown in FIG. 56. With occlusion balloon 620 expanded, the vessel
may be occluded and blood flow temporarily halted from entering the
left atrium LA. Hood 12 may then be positioned along or around the
ostium OT and the contained space encompassed between the hood 12
and occlusion balloon 620 may be infused with the clear fluid 528
to create a cleared visualization area 622 within which the ostium
OT and surrounding tissue may be visualized via imaging element 532
and accordingly treated using any of the ablation instruments
described herein, as practicable.
[0227] Aside from use of an occlusion balloon, articulation and
manipulation of hood 12 within a beating heart with dynamic fluid
currents may be further facilitated utilizing support members. In
one variation, one or more grasping support members may be passed
through catheter 16 and deployed from hood 12 to allow for the hood
12 to be walked or moved along the tissue surfaces of the heart
chambers. FIG. 57 shows a perspective view of hood 12 with a first
tissue grasping support member 630 having a first tissue grasper
634 positioned at a distal end of member 630. A distal portion of
member 630 may be angled via first angled or curved portion 632 to
allow for tissue grasper 634 to more directly approach and adhere
onto the tissue surface. Similarly, second tissue grasping support
member 636 may extend through hood 12 with second angled or curved
portion 638 and second tissue grasper 640 positioned at a distal
end of member 638. Although illustrated in this variation as a
helical tissue engager, other tissue grasping mechanisms may be
alternatively utilized.
[0228] As illustrated in FIGS. 58A to 58C, with hood 12 expanded
within the left atrium LA, first and second tissue graspers 634,
640 may be deployed and advanced distally of hood 12. First tissue
grasper 634 may be advanced into contact with a first tissue region
adjacent to the ostium OT and torqued until grasper 634 is engaged
to the tissue, as shown in FIG. 58A. With grasper 634 temporarily
adhered to the tissue, second tissue grasper 640 may be moved and
positioned against a tissue region adjacent to first tissue grasper
636 where it may then be torqued and temporarily adhered to the
tissue, as shown in FIG. 58B. With second grasper 640 now adhered
to the tissue, first grasper 636 may be released from the tissue
and hood 12 and first tissue grasper 636 may be angled to another
region of tissue utilizing first second grasper 640 as a pivoting
point to facilitate movement of hood 12 along the tissue wall, as
shown in FIG. 58C. This process may be repeated as many times as
desired until hood 12 has been positioned along a tissue region to
be treated or inspected.
[0229] FIG. 59 shows another view illustrating first tissue grasper
634 extended from hood 12 and temporarily engaged onto the tissue
adjacent to the pulmonary vein, specifically the right inferior
pulmonary vein PV.sub.RI which is generally difficult to access in
particular because of its close proximity and tight angle relative
to the transseptal point of entry through the atrial septum AS into
the left atrium LA. With catheter 16 retroflexed to point hood 12
generally in the direction of the right inferior pulmonary vein
PV.sub.RI and with first tissue grasper 634 engaged onto the
tissue, hood 12 and deployment catheter 16 may be approximated
towards the right inferior pulmonary vein ostium with the help of
the grasper 634 to inspect and/or treat the tissue.
[0230] FIG. 60 illustrates an alternative method for the tissue
visualization catheter to access the left atrium LA of the heart H
to inspect and/or treat the areas around the pulmonary veins PV.
Using an intravascular trans-femoral approach, deployment catheter
16 may be advanced through the aorta AO, through the aortic valve
AV and into the left ventricle LV, through the mitral valve MV and
into the left atrium LA. Once within the left ventricle LV, a
helical tissue grasper 84 may be extended through hood 12 and into
contact against the desired tissue region to facilitate inspection
and/or treatment.
[0231] When utilizing the tissue grasper to pull hood 12 and
catheter 16 towards the tissue region for inspection or treatment,
adequate force transmission to articulate and further advance the
catheter 16 may be inhibited by the tortuous configuration of the
catheter 16. Accordingly, the first tissue grasper 634 can be used
optionally to loop a length of wire or suture 650 affixed to one
end of hood 12 and through the secured end of the first grasper
634, as shown in FIG. 61A. The suture 650, routed through catheter
16, can be subsequently pulled from its proximal end from outside
the patient body (as indicated by the direction of tension 652) to
provide additional pulling strength for the catheter 16 to move
distally along the length of member 630 like a pulley system (as
indicated by the direction of hood movement 654, as illustrated in
FIG. 61B. FIGS. 61C and 61D further illustrate the tightly-angled
configuration which catheter 16 and hood 12 must conform to and the
relative movement of tensioned suture 650 with the resulting
direction of movement 654 of hood 12 into position against the
ostium OT. Under such a pulley mechanism, the hood 12 may also
provide additional pressure on the target tissue to provide a
better seal between the hood 12 and the tissue surface.
[0232] In yet another variation for the ablation treatment of
intra-atrial tissue, FIG. 62A shows sheath 14 positioned
transseptally with a transparent intra-atrial balloon 660 inflated
to such a size as to occupy a relatively large portion of the
atrial chamber, e.g., 75% or more of the volume of the left atrium
LA. Balloon 660 may be inflated by a clear fluid such as saline or
a gas. Visualization of tissue surfaces in contact against the
intra-atrial balloon 660 becomes possible as bodily opaque fluids,
such as blood, is displaced by the balloon 660. It may also be
possible to visualize and identify a number of ostia of the
pulmonary veins PV through balloon 660. With the position of the
pulmonary veins PV identified, the user may orient instruments
inside the cardiac chamber by using the pulmonary veins PV as
anatomical landmarks.
[0233] FIGS. 62B and 62C illustrate an imaging instrument, such as
a fiberscope 662, advanced at least partially within the
intra-atrial balloon 660 to survey the cardiac chamber as well as
articulating the fiberscope 662 to obtain closer images of tissue
regions of interest as well as to navigate a wide range of motion.
FIG. 62D illustrates a variation of balloon 660 where one or more
radio-opaque fiducial markers 664 may be positioned over the
balloon such that a position and inflation size of the balloon 660
may be tracked or monitored by extracorporeal imaging modalities,
such as fluoroscopy, magnetic resonance imaging, computed
tomography, etc.
[0234] With balloon 660 inflated and pressed against the atrial
tissue wall, in order to access and treat a tissue region of
interest within the chamber, a needle catheter 666 having a
piercing ablation tip 668 may be advanced through a lumen of the
deployment catheter and into the interior of the balloon 660. The
needle catheter 666 may be articulated to direct the ablation tip
668 to the tissue to be treated and the ablation tip 668 may be
simply advanced to pierce through the balloon 660 and into the
underlying tissue, where ablation treatment may be effected, as
shown in FIG. 63. Provided that the needles projecting from
ablation tip 668 are sized sufficiently small in diameter and are
gently inserted through the balloon 660, leakage or bursting of the
balloon 660 may be avoided. Alternatively, balloon 660 may be
fabricated from a porous material such that the injected clear
fluid, such as saline, may diffuse out of the balloon 660 to
provide a medium for RF tissue ablation by enabling a circuit
between the positive and negative electrode to be closed through
the balloon wall by allowing the diffused saline to be an
intermediate conductor. Other ablation instruments such as laser
probes can also be utilized and inserted from within the balloon
660 to access the tissue region to be treated.
[0235] FIGS. 64A and 64B illustrate detail views of a safety
feature where one or more ablation probes 672 are deployable from a
retracted configuration, as shown in FIG. 64A, where each probe is
hidden its respective opening 670 when unused. This prevents an
unintended penetration of the balloon 660 or inadvertent ablation
to surrounding tissue around the treatment area. When the tissue is
to be treated, the one or more probes 672 may be projected from
their respective openings 670, as shown in FIG. 64B. The ablation
probes 672 may be configured as a monopolar electrode assembly.
FIG. 64C illustrates a perspective view of an ablation catheter 666
configured as a bipolar probe including a return electrode 674.
Return electrode 674 may be positioned proximally of probes 672,
e.g., about 10 mm, along shaft 666.
[0236] In yet another variation, FIG. 65A shows a stabilizing
sheath 14 which may be advanced through the inferior vena cava IVC,
as above, in a flexible state. Once sheath 14 has been desirably
positioned within the right atrium RA, its configuration may be
optionally locked or secured such that its shape is retained
independently of instruments which may be advanced therethrough or
independently of the motion of the heart. Such a locking
configuration may be utilized via any number of mechanisms as known
in the art.
[0237] In either case, sheath 14 may have a stabilizing balloon
680, similar to that described above, which may be expanded within
the right atrium RA to inflate until the balloon 680 touches the
walls of the chamber to provide stability to the sheath 14, as
shown in FIG. 65B. The tip of the sheath 14 may be farther advanced
to perform a transseptal procedure to the left atrium LA utilizing
any of the methods and/or devices as described in further detail in
U.S. patent application Ser. No. 11/763,399 filed Jun. 14, 2007,
which has been incorporated above.
[0238] Once the sheath 14 has been introduced transseptally into
the left atrium LA, an articulatable section 682 may be steered as
indicated by the direction of articulation 684 into any number of
directions, such as by pullwires, to direct the sheath 14 towards a
region of tissue to be treated, such as the pulmonary vein ostium,
as shown in FIG. 65C. With the steerable section 682 desirably
pointed towards the tissue to be treated, the amount of force
transmission and steering of the tissue visualization catheter
towards the tissue region is reduced and simplified.
[0239] FIG. 65D shows illustrates an example of the telescoping
capability of the deployment catheter 16 and hood 12 from the
steerable sheath 14 into the left atrium LA, as indicated by the
direction of translation 686. Furthermore, FIG. 65E also
illustrates an example of the articulating ability of the sheath 14
with deployment catheter 16 and hood 12 extended from sheath 14, as
indicated by the direction of articulation 690. Deployment catheter
16 may also comprise a steerable section 688 as well. With each
degree of articulation and translation capability, hood 12 may be
directed to any number of locations within the right atrium RA to
effect treatment.
[0240] FIGS. 66A and 66B illustrate yet another variation where
sheath 14 may be advanced transseptally at least partially along
its length, as shown in FIG. 66A, as above. In this variation,
rather than use of a single intra-atrial stabilizing balloon, a
proximal stabilization balloon 700 inflatable along the atrial
septum within the right atrium RA and a distal stabilization
balloon 702 inflatable along the atrial septum within the left
atrium LA may be inflated along the sheath 14 to sandwich the
atrial septum AS between the balloons 700, 702 to provide
stabilization to the sheath 14, as shown in FIG. 66B. With sheath
14 stabilized, a separate inner sheath 704 may be introduced from
sheath 14 into the left atrium LA. Inner sheath 704 may comprise an
articulatable section 706 as indicated by the direction of
articulation 708 and as shown in FIG. 66C. Also, inner sheath 704
may also be translated distally further into the left atrium LA as
indicated by the direction of translation 710 to establish as short
a trajectory for hood 12 to access any part of the left atrium LA
tissue wall. With the trajectory determined by the articulation and
translation capabilities, deployment catheter 16 may be advanced
with hood 12 to expand within the left atrium LA with a relatively
direct approach to the tissue region to be treated, such as the
ostium OT of the pulmonary veins, as shown in FIG. 66E.
[0241] FIGS. 67A and 67B illustrate yet another variation where
sheath 14 may be advanced at least partially through the atrial
septum AS and proximal and distal stabilization balloons 700, 702
may be expanded against the septal wall. Similar to the variation
above in FIGS. 62A to 62C, an intra-atrial balloon 660 may be
expanded from the distal opening of sheath 14 to expand and occupy
a volume within the right atrium RA. Fiberscope 662 may be advanced
at least partially within the intra-atrial balloon 660 to survey
the cardiac chamber, as illustrated in FIG. 67C. Once a pulmonary
vein ostium has been visually identified for treatment, inner
sheath 704 may be introduced from sheath 14 into the left atrium LA
and articulated and/or translated to direct its opening towards the
targeted tissue region to be treated. With a trajectory determined,
a penetrating needle 720 having a piercing tip 722 and a hollow
lumen sufficiently sized to accommodate hood 12 and deployment
catheter 16, may be advanced from inner sheath 704 and into contact
against the balloon 660 to pierce through and access the targeted
tissue for treatment, as shown in FIGS. 67D and 67E. With the
piercing tip 722 extended into the pulmonary vein PV, penetrating
needle 720 may be withdrawn to allow for the advancement of hood 12
in its low profile shape to be advanced through the pierced balloon
660 or hood 12 and deployment catheter 16 may be advanced distally
through the lumen of needle 720 where hood 12 may be expanded
externally of balloon 660. With the hood 12 deployed, catheter 16
may be retracted partially into inner sheath 704 such that hood 12
occupies and seals the pierced opening through balloon 660. Hood 12
may also placed into direct contact with the targeted tissue for
treatment externally of balloon 660, as illustrated in FIG.
67F.
[0242] In utilizing the intra-atrial balloon 660, a direct visual
image of the atrial chamber may be provided through the balloon
interior. Because an imager such as fiberscope 662 has a limited
field of view, multiple separate images captured by the fiberscope
662 may be processed to provide a combined panoramic image or
visual map of the entire atrial chamber. An example is illustrated
in FIG. 68A where a first recorded image 730 (represented by "A")
may be taken by the fiberscope 662 at a first location within the
atrial chamber. A second recorded image 732 (represented by "B")
may likewise be taken at a second location adjacent to the first
location. Similarly, a third recorded image 734 (represented by
"C") may be taken at a third location adjacent to the second
location.
[0243] The individual captured images 730, 732, 734 can be sent to
an external CPU via wireless technology such as Bluetooth.RTM.
(BLUETOOTH SIG, INC, Bellevue, Wash.) or other wireless protocols
while the tissue visualization catheter is within the cardiac
chamber. The CPU can process the pictures taken by monitoring the
trajectory of articulation of the fiberscope or CCD camera, and
process a two-dimensional or three-dimensional visual map of the
patient's heart chamber simultaneously while the pictures are being
taken by the catheter utilizing any number of known imaging
software to combine the images into a single panoramic image 736 as
illustrated schematically in FIG. 68B. The operator can
subsequently use this visual map to perform a therapeutic treatment
within the heart chamber with the visualization catheter still
within the cardiac chamber of the patient. The panoramic image 736
of the heart chamber generated can also be used in conjunction with
conventional catheters that are able to track the position of the
catheter within the cardiac chamber by imaging techniques such as
fluoroscopy but which are unable to provide direct real time
visualization.
[0244] A potential complication in ablating the atrial tissue is
potentially piercing or ablating outside of the heart H and
injuring the esophagus ES (or other adjacent structures), which is
located in close proximity to the left atrium LA. Such a
complication may arise when the operator is unable to estimate the
location of the esophagus ES relative to the tissue being ablated.
In one example of a safety mechanism shown in FIG. 69A, a light
source or ultrasound transducer 742 may be attached to or through a
catheter 740 which can be inserted transorally into the esophagus
ES and advanced until the catheter light source 742 is positioned
proximate to or adjacent to the heart H. During an intravascular
ablation procedure in the left atrium LA, the operator may utilize
the imaging element to visually (or otherwise such as through
ultrasound) detect the light source 742 in the form of a background
glow behind the tissue to be ablated as an indication of the
location of the esophagus ES. Different light intensities providing
different brightness or glow in the tissue can be varied to
represent different safety tolerances, e.g., the stronger the light
source 742, the easier detection of the glow in the left atrium LA
by the imaging element and potentially greater safety margin in
preventing an esophageal perforation.
[0245] An alternative method is to insert an ultrasound crystal
source at the end of the transoral catheter instead of a light
source. An ultrasound crystal receiver can be attached to the
distal end of the hood 12 in the left atrium LA. Through the
communication between the ultrasound crystal source and receiver,
the distance between the ablation tool and the esophagus ES can be
calculated by a processor. A warning, e.g., in the form of a beep
or vibration on the handle of the ablation tools, can activate when
the source in the heart H approaches the receiver located in the
esophagus ES indicating that the ablation probe is approaching the
esophagus ES at the ablation site. The RF source can also cut off
its supply to the electrodes when this occurs as part of the safety
measure.
[0246] Another safety measure which may be utilized during tissue
ablation is the utilization of color changes in the tissue being
ablated. One particular advantage of a direct visualization system
described herein is the ability to view and monitor the tissue in
real-time and in detailed color. Thus, as illustrated in the side
view of FIG. 69C, hood 12 is placed against the tissue T to be
ablated and any blood within hood 12 is displaced with transparent
saline fluid. Imaging element 532 may provide the off-axis
visualization of the ablation probe 536 placed against the tissue
surface for treatment, as illustrated in FIG. 69B by the displayed
image of a representative real-time view that the user would see on
monitor 128. As the tissue is heated by ablation probe 536,
represented by heated tissue 745 in FIG. 69E, the resulting color
change of the ablated tissue 744 may be detected and monitored on
monitor 128 as the ablated tissue 744 turns from a pink color to a
pale white color indicative of ablation or irreversible tissue
damage, as shown in FIG. 69D. The user may monitor the real-time
image to ensure that an appropriate amount and location of tissue
is ablated and is not over-heated by tracking the color changes on
the tissue surface.
[0247] Furthermore, the real-time image may be monitored for the
presence of any steam or micro-bubbles, which are typically
indications of endocardial disruptions, emanating from the ablated
tissue. If detected, the user may cease ablation of the tissue to
prevent any further damage from occurring.
[0248] In another indication of tissue damage, FIGS. 69F and 69G
show the release of tissue debris 747, e.g., charred tissue
fragments, coagulated blood, etc., resulting from an endocardial
disruption or tissue "popping" effect. The resulting tissue crater
746 may be visualized, as shown in FIG. 69F, as well as the
resulting tissue debris 747. When the disruption occurs, ablation
may be ceased by the user and the debris 747 may be contained
within hood 12 and prevented from release into the surrounding
environment, as shown in FIG. 69G. The contained or captured debris
747 within hood 12 maybe evacuated and removed from the patient
body by drawing the debris 747 via suction proximally from within
hood 12 into the deployment catheter, as indicated by the direction
of suction 748 in FIG. 69H. Once the captured debris 747 has been
removed, ablation may be completed upon the tissue and/or the hood
12 may be repositioned to treat another region of tissue.
[0249] Yet another method for improving the ablation treatment upon
the tissue and improving safety to the patient is shown in FIGS.
69I to 69K. The hood 12 may be placed against the tissue to be
treated T and the blood within the hood 12 displaced by saline, as
above and as shown in FIG. 69I. Once the appropriate tissue region
to be treated has been visually identified and confirmed, negative
pressure may be formed within the hood 12 by withdrawing the saline
within the hood 12 to create a suction force until the underlying
tissue is drawn at least partially into the hood interior, as shown
in FIG. 69J. The temporarily adhered tissue 749 may be in stable
contact with hood 12 and ablation probe 536 may be placed into
contact with the adhered tissue 749 such that the tissue 749 is
heated in a consistent manner, as illustrated in FIG. 69K. Once the
ablation has been completed, the adhered tissue 749 may be released
and hood 12 may be re-positioned to effect further treatment on
another tissue region.
[0250] The applications of the disclosed invention discussed above
are not limited to certain treatments or regions of the body, but
may include any number of other treatments and areas of the body.
Modification of the above-described methods and devices for
carrying out the invention, and variations of aspects of the
invention that are obvious to those of skill in the arts are
intended to be within the scope of this disclosure. Moreover,
various combinations of aspects between examples are also
contemplated and are considered to be within the scope of this
disclosure as well.
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