U.S. patent application number 15/158475 was filed with the patent office on 2016-12-22 for optically guided surgical devices.
The applicant listed for this patent is Children's Medical Center Corporation. Invention is credited to Asghar Ataollahi, Ignacio Berra, Pedro J. del Nido, Pierre Dupont, Zurab Machaidze, Sunil Manjila, Margherita Mencatelli, Benoit Rosa.
Application Number | 20160367120 15/158475 |
Document ID | / |
Family ID | 57546747 |
Filed Date | 2016-12-22 |
United States Patent
Application |
20160367120 |
Kind Code |
A1 |
Dupont; Pierre ; et
al. |
December 22, 2016 |
Optically Guided Surgical Devices
Abstract
A device for performing surgical procedures, such as
intracardiac procedures or neurosurgical procedures, includes a
solid optical window formed of a transparent, compliant material,
wherein the solid optical window includes a proximal side and a
distal side, wherein a distal face of the solid optical window is
configured to approach tissue during a surgical procedure; an
imaging system embedded into the solid optical window and
positioned to obtain an image through at least a portion of the
distal face of the solid optical window; and a tool channel formed
through the solid optical window from the proximal side to the
distal side of the solid optical window, wherein the tool channel
is configured to receive a tool for performing the surgical
procedure.
Inventors: |
Dupont; Pierre; (Wellesley,
MA) ; Ataollahi; Asghar; (Brookline, MA) ; del
Nido; Pedro J.; (Lexington, MA) ; Berra; Ignacio;
(Boston, MA) ; Mencatelli; Margherita; (Boston,
MA) ; Manjila; Sunil; (Boston, MA) ; Rosa;
Benoit; (Brookline, MA) ; Machaidze; Zurab;
(Lexington, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Children's Medical Center Corporation |
Boston |
MA |
US |
|
|
Family ID: |
57546747 |
Appl. No.: |
15/158475 |
Filed: |
May 18, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62182204 |
Jun 19, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 1/00179 20130101;
A61B 10/0283 20130101; A61B 1/05 20130101; A61B 1/00096 20130101;
A61B 1/018 20130101; A61B 17/00234 20130101; A61B 1/015 20130101;
A61B 2017/00243 20130101; A61B 10/02 20130101; A61B 1/00087
20130101; A61B 10/04 20130101 |
International
Class: |
A61B 1/018 20060101
A61B001/018; A61B 10/02 20060101 A61B010/02; A61B 1/015 20060101
A61B001/015; A61B 1/07 20060101 A61B001/07 |
Goverment Interests
STATEMENT AS TO FEDERALLY SPONSORED RESEARCH
[0002] This invention was made with Government support under Grant
No. R01HL124020 awarded by the National Institutes of Health. The
Government has certain rights in the invention.
Claims
1. A device for performing surgical procedures, the device
comprising: a solid optical window formed of a transparent,
compliant material, wherein the solid optical window comprises a
proximal side and a distal side, wherein a distal face of the solid
optical window is configured to approach tissue during a surgical
procedure; an imaging system embedded into the solid optical window
and positioned to obtain an image through at least a portion of the
distal face of the solid optical window; and a tool channel formed
through the solid optical window from the proximal side to the
distal side of the solid optical window, wherein the tool channel
is configured to receive a tool for performing the surgical
procedure.
2. The device of claim 1, wherein the solid optical window is
formed from a polymer.
3. The device of claim 1, wherein the solid optical window is
formed from silicone or silicone rubber.
4. The device of claim 1, wherein the distal face of the solid
optical window is planar.
5. The device of claim 1, wherein a normal to the distal face of
the solid optical window is disposed at an angle greater than
0.degree. relative to a longitudinal axis of the solid optical
window.
6. The device of claim 1, wherein the imaging system comprises one
or more cameras or optical fibers.
7. The device of claim 1, wherein the imaging system comprises one
or more illumination devices.
8. The device of claim 1, wherein, when no tool is present in the
tool channel, the tool channel is sealed.
9. The device of claim 1, wherein, when no tool is present in the
tool channel, the tool channel collapses closed.
10. The device of claim 1, wherein the tool channel is offset
laterally relative to a central axis of the solid optical
window.
11. The device of claim 1, wherein a longitudinal axis of the tool
channel is disposed at an angle between 0.degree. and 90.degree.
relative to a longitudinal axis of the solid optical window.
12. The device of claim 1, wherein a longitudinal axis of the tool
channel is disposed at an angle greater than 0.degree. relative to
a longitudinal axis of a distal portion of the imaging system.
13. The device of claim 1, further comprising a tube disposed in a
proximal portion of the tool channel.
14. The device of claim 1, wherein the surgical procedure includes
an intracardiac procedure and wherein the distal face of the solid
optical window is configured to come into contact with cardiac
tissue.
15. The device of claim 1, wherein the device is mounted on or
integrated into a distal end of a catheter.
16. The device of claim 1, wherein the surgical procedure includes
a neurosurgical procedure and wherein the distal face of the solid
optical window is configured to come into contact with brain
tissue.
17. The device of claim 16, wherein the device is mounted on or
integrated into a distal end of a neuroendoscope.
18. The device of claim 16, wherein the device is mounted on or
integrated into a lateral surface of a neuroendoscope.
19. The device of claim 1, further comprising a flushing channel
formed through the solid optical window from the proximal face to
the distal face of the solid optical window.
20. The device of claim 19, further comprising a tube disposed in a
proximal portion of the flushing channel.
21. The device of claim 19, wherein, when no liquid is present in
the flushing channel, the flushing channel is sealed.
22. The device of claim 1, including multiple tool channels formed
through the solid optical window.
23. The device of claim 22, wherein a longitudinal axis of a first
one of the multiple tool channels is disposed at an angle greater
than 0.degree. relative to a longitudinal axis of a second one of
the multiple tool channels.
24. The device of claim 22, wherein the imaging system is
positioned to obtain an image of a distal opening of one or more of
the multiple tool channels.
25. The device of claim 22, wherein the multiple tool channels are
positioned such that the tools received by the multiple tool
channels meet at a surgical site, and wherein the imaging system is
positioned to obtain an image of the tools meeting at the surgical
site.
26. A method for performing a surgical procedure, the method
including: inserting an instrument into a patient, the instrument
comprising a solid optical window at a distal end of the
instrument, the solid optical window formed of a transparent,
compliant material; causing a distal face of the solid optical
window to approach tissue of the patient; inserting a tool through
a tool channel in the solid optical window, the tool channel formed
through the solid optical window from a proximal side to a distal
side of the solid optical window; and obtaining an image of the
tissue, the tool, or both through at least a portion of the distal
face of the solid optical window.
27. The method of claim 26, further comprising performing a beating
heart intracardiac procedure using the tool.
28. The method of claim 27, wherein causing the distal face of the
solid optical window to approach tissue of the patient comprises
causing the distal face of the solid optical window to come into
contact with the tissue.
29. The method of claim 26, further comprising performing a
neurosurgical procedure using the tool.
30. The method of claim 26, wherein obtaining an image comprises
obtaining an image of the tissue prior to causing the distal face
of the solid optical window to come into contact with the
tissue.
31. The method of claim 26, further comprising controlling a depth
of penetration of the tool into the tissue.
32. The method of claim 26, further comprising controlling an angle
between the tool and the tissue.
33. A device for performing surgical procedures, the device
comprising: a hollow optical window formed of a transparent,
compliant material, wherein the hollow optical window is configured
to be filled with saline, wherein a distal face of the solid
optical window is configured to approach tissue during a surgical
procedure, the hollow optical window disposed on a distal end of an
instrument; an imaging system in the instrument and positioned to
obtain an image through at least a portion of the distal face of
the hollow optical window; and a tool channel formed through the
instrument, wherein the tool channel is configured to receive a
tool for performing the surgical procedure, wherein the hollow
optical window is configured to allow the tool to pass through the
window to perform the surgical procedure.
34. The device of claim 33, wherein a position at which the tool
passes through the window can be adjusted.
35. The device of claim 33, wherein a position of the imaging
system in the instrument can be adjusted.
36. The device of claim 33, wherein the hollow optical window is
configured to expand when filled with saline.
Description
CLAIM OF PRIORITY
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 62,182,204, filed on Jun. 19, 2015, the
contents of which are incorporated here by reference in their
entirety.
FIELD OF THE INVENTION
[0003] The invention relates to devices and methods for surgical
imaging, such as during an intracardiac or neurosurgical
procedure.
BACKGROUND
[0004] Vascular heart disease is an important health problem
afflicting over 2.5% of the U.S. population. A variety of
percutaneous and transcardiac procedures for valve replacement have
been developed. Catheter-based interventions provide a relatively
low-risk opportunity to intervene earlier in the disease process,
as well as in the sickest patients, while avoiding the risks of
cardiopulmonary bypass. Procedures that can be performed via
catheter include transcatheter aortic valve replacement and
catheter-delivered clips to reduce or eliminate mitral valve
regurgitation. Beating-heart interventions also provide the
opportunity for continuous intra-operative assessment of the
repair. Catheter-based or endoscopic interventions can also be used
for other medical procedures, such as neurosurgical procedures.
SUMMARY
[0005] This disclosure is based, at least in part, on the discovery
that surgical procedures, such as intracardiac procedures or
neurosurgical procedures, can be guided by imaging provided through
an optical window integrated on the distal tip of an instrument to
be inserted into a surgical site, such as into a beating heart or
into brain tissue. Imaging at the surgical site (e.g., within the
heart or brain) before, during, and after a procedure provides for
image-guided positioning of instruments or of tools or devices
guided by or inserted by the instrument, such as a tissue removal
tool, a catheter, a tissue gripping device, a mitral valve clip, or
another tool. Imaging at the surgical site can also enable reliable
detection of contact between the instrument, tool, or device and
the target tissue, as well as the ability to stabilize and control
the position of the instrument, tool, or device relative to the
target tissue. Once the instrument, tool or device is positioned,
procedures, such as procedures within the beating heart or
neurosurgical procedures, can be carried out under image guidance,
and the result of the procedure can be visualized in vivo and in
real time.
[0006] In an aspect, a device for performing surgical procedures
includes a solid optical window formed of a transparent, compliant
material, wherein the solid optical window includes a proximal side
and a distal side, wherein a distal face of the solid optical
window is configured to approach tissue during a surgical
procedure; an imaging system embedded into the solid optical window
and positioned to obtain an image through at least a portion of the
distal face of the solid optical window; and a tool channel formed
through the solid optical window from the proximal side to the
distal side of the solid optical window, wherein the tool channel
is configured to receive a tool for performing the surgical
procedure.
[0007] Embodiments can include one or more of the following
features.
[0008] The solid optical window is formed from a polymer.
[0009] The solid optical window is formed from silicone or silicone
rubber.
[0010] The distal face of the solid optical window is planar.
[0011] A normal to the distal face of the solid optical window is
disposed at an angle greater than 0.degree. relative to a
longitudinal axis of the solid optical window.
[0012] The normal to the distal face is disposed at an angle of
between 20-25.degree. relative to the longitudinal axis of the
solid optical window.
[0013] A first diameter of a proximal portion of the solid optical
window is greater than a second diameter of a distal portion of the
solid optical window.
[0014] The imaging system is embedded in the proximal portion of
the solid optical window.
[0015] The imaging system includes a camera or an optical fiber,
such as one or more cameras or optical fibers.
[0016] The imaging system includes one or more illumination
devices.
[0017] When no tool is present in the tool channel, the tool
channel is sealed.
[0018] When no tool is present in the tool channel, the tool
channel appears as a thin line in an image acquired by the imaging
system.
[0019] When no tool is present in the tool channel, the tool
channel collapses closed.
[0020] The tool channel is offset laterally relative to a central
axis of the solid optical window.
[0021] A longitudinal axis of the tool channel is disposed at an
angle between 0.degree. and 90.degree. relative to a longitudinal
axis of the solid optical window.
[0022] A longitudinal axis of the tool channel is disposed at an
angle greater than 0.degree. relative to a longitudinal axis of a
distal portion of the imaging system.
[0023] The device includes a tube disposed in a proximal portion of
the tool channel.
[0024] The tube is formed of a rigid material.
[0025] The tube is disposed outside of a field of view of the
imaging system.
[0026] The surgical procedure includes an intracardiac procedure.
The distal face of the solid optical window is configured to come
into contact with cardiac tissue.
[0027] The tool for performing an intracardiac procedure includes a
tissue removal tool.
[0028] The device is mounted on or integrated into a distal end of
a catheter.
[0029] The tool for performing an intracardiac procedure includes a
tissue gripping device.
[0030] The tool for performing an intracardiac procedure includes
one or more clips configured to be attached to a cardiac valve
leaflet.
[0031] The surgical procedure includes a neurosurgical procedure.
The distal face of the solid optical window is configured to come
into contact with brain tissue.
[0032] The device is mounted on or integrated into a distal end of
a neuroendoscope.
[0033] The device is mounted on or integrated into a lateral
surface of a neuroendoscope.
[0034] The device includes a flushing channel formed through the
solid optical window from the proximal face to the distal face of
the solid optical window.
[0035] The flushing channel is configured to eject a liquid from an
opening in the distal face of the solid optical window.
[0036] The device includes a tube disposed in a proximal portion of
the flushing channel.
[0037] The tube is disposed outside of a field of view of the
imaging system.
[0038] When no liquid is present in the flushing channel, the
flushing channel is sealed.
[0039] When no liquid is present in the flushing channel, the
flushing channel appears as a thin line in an image acquired by the
imaging system.
[0040] The device includes multiple tool channels formed through
the solid optical window.
[0041] A longitudinal axis of a first one of the multiple tool
channels is disposed at an angle greater than 0.degree. relative to
a longitudinal axis of a second one of the multiple tool
channels.
[0042] The imaging system is positioned to obtain an image of a
distal opening of one or more of the multiple tool channels.
[0043] The multiple tool channels are positioned such that the
tools received by the multiple tool channels meet at a surgical
site, and wherein the imaging system is positioned to obtain an
image of the tools meeting at the surgical site.
[0044] In a general aspect, a method for performing a surgical
procedure includes inserting an instrument into a patient, the
instrument including a solid optical window at a distal end of the
instrument, the solid optical window formed of a transparent,
compliant material; causing a distal face of the solid optical
window to come approach tissue of the patient; inserting a tool
through a tool channel in the solid optical window, the tool
channel formed through the solid optical window from a proximal
side to a distal side of the solid optical window; and obtaining an
image of the tissue, the tool, or both through at least a portion
of the distal face of the solid optical window.
[0045] Embodiments can include one or more of the following
features.
[0046] The instrument includes a catheter.
[0047] The method includes performing a beating heart intracardiac
procedure using the tool.
[0048] The beating heart intracardiac procedure includes a valve
repair.
[0049] Causing the distal face of the solid optical window to
approach tissue of the patient comprises causing the distal face of
the solid optical window to come into contact with the tissue.
[0050] The method includes performing a neurosurgical procedure
using the tool.
[0051] Obtaining an image includes obtaining an image of the tissue
prior to causing the distal face of the solid optical window to
come into contact with the tissue.
[0052] The method includes controlling a depth of penetration of
the tool into the tissue.
[0053] The method includes controlling an angle between the tool
and the tissue.
[0054] A device for performing surgical procedures includes a
hollow optical window formed of a transparent, compliant material.
The hollow optical window is configured to be filled with saline. A
distal face of the solid optical window is configured to approach
tissue during a surgical procedure. The hollow optical window is
disposed on a distal end of an instrument. The device includes an
imaging system in the instrument and positioned to obtain an image
through at least a portion of the distal face of the hollow optical
window. The device includes a tool channel formed through the
instrument and configured to receive a tool for performing the
surgical procedure. The hollow optical window is configured to
allow the tool to pass through the window to perform the surgical
procedure.
[0055] Embodiments can include one or more of the following
features.
[0056] A position at which the tool passes through the window can
be adjusted.
[0057] A position of the imaging system in the instrument can be
adjusted.
[0058] The hollow optical window is configured to expand when
filled with saline.
[0059] The devices and methods for cardiac imaging described herein
can have one or more of the following advantages. The device can be
manipulated, stabilized, and positioned relative to the target
tissue, such as cardiac tissue in a beating heart, for precise
control of tool operation. For instance, in some examples, tissue
contact with the optical window allows the depth of penetration of
a tool into tissue or the contact angle of the tool with tissue of
a beating heart to be precisely controlled, thus reducing the
likelihood of both damage to the tissue, such as accidental damage
of sensitive heart structures or perforation of the heart wall, and
damage to the tool.
[0060] A large field of view is available that is only minimally
occluded when no tool has been inserted into the optical window,
thus enabling clear visualization at and in the vicinity of the
target tissue. The optical window provides the ability to obtain
high resolution (e.g., sub-millimeter resolution), in vivo images
of device deployment and function in a beating heart and of
detailed anatomy of the target tissue before, during, and after a
procedure. A clear view can be achieved without continuous saline
infusion during imaging, and there is a low likelihood of leakage
into or out of the optical window. Light reflection from surfaces
and interfaces is low and thus high image quality, low image
deformation, and good focus can be obtained. The optical window is
inexpensive to fabricate and can be sized for integration into a
variety of devices for in vivo intracardiac procedures.
[0061] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, suitable methods and materials are described below. All
publications, patent applications, patents, and other references
mentioned herein are incorporated by reference in their entirety.
In case of conflict, the present specification, including
definitions, will control. In addition, the materials, methods, and
examples are illustrative only and not intended to be limiting.
[0062] Other features and advantages of the invention will be
apparent from the following detailed description, and from the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0063] FIG. 1 is a diagram of an instrument for image-guided
intracardiac procedures.
[0064] FIG. 2 is a diagram of an optical window for an instrument
for image-guided intracardiac procedures.
[0065] FIGS. 3A and 3B are photographs taken during use of an
optical window.
[0066] FIGS. 4-6 are diagrams of example instruments having optical
windows.
[0067] FIGS. 7A-7C are diagrams of an example instrument having an
optical window.
[0068] FIGS. 8A-8D are diagrams of various examples of the optical
window.
[0069] FIG. 9A is a diagram of an optical window having two
cameras.
[0070] FIG. 9B is a diagram of an optical window having two tool
channels.
[0071] FIG. 10 is a schematic diagram of the interior of a heart
illustrating placement of one of the devices described herein.
[0072] FIGS. 11A-11C are diagrams of a tissue removal tool as
described herein.
[0073] FIG. 12 is a flow chart of a procedure for using an optical
window with a tissue removal tool.
[0074] FIG. 13 is a photograph of a cardioscope.
[0075] FIG. 14 is a diagram of a catheter with a distal cardioscope
for repairing a paravalvular leak.
[0076] FIG. 15 is a diagram of a catheter with a distal cardioscope
for manipulation of a mitral leaflet.
[0077] FIGS. 16A and 16B are diagrams of a mitral valve clip and a
tissue gripping device, respectively, with a distal
cardioscope.
[0078] FIG. 17 is a diagram of an optical window with a fiducial
marking.
[0079] FIG. 18 is a diagram of an alternative example of an optical
window.
[0080] FIG. 19 is a diagram of an optical window with a pattern of
crosshairs.
[0081] FIGS. 20A-20C and 21 are diagrams of an optical window with
an expandable bulb.
[0082] FIGS. 22A and 22B are photographs and a diagram,
respectively, of a multi-port neuroendoscope having optical
windows.
[0083] FIGS. 23A-23D are photographs of tissue removal in an ex
vivo beating heart experiment.
[0084] FIG. 24 is a photograph of an in vivo beating heart
experiment.
[0085] FIGS. 25A-25F are photographs of tissue removal in an in
vivo beating heart experiment.
[0086] FIGS. 26A-26C are photographs of post-surgical evaluation of
in vivo tissue removal from a beating heart.
[0087] FIG. 27 shows images of a replacement aortic valve installed
in a pig.
[0088] FIGS. 28A-28D are diagrams of a multi-port neuroendoscope
having a distal optical window and a lateral optical window.
[0089] FIG. 29 shows images of an imaging target taken using
various types of neuroendoscopes.
[0090] FIG. 30 shows images of a multi-port neuroendoscope inside a
porcine brain.
[0091] FIGS. 31A and 31B are photographs of tissue visualization by
a multi-port neuroendoscope.
[0092] FIGS. 32A-32F are photographs acquired during fenestration
and aspiration of a colloid cyst using a multi-port
neuroendoscope.
[0093] FIGS. 33A-33E are photographs acquired during septostomy
using the lateral port of a multi-port neuroendoscope.
DETAILED DESCRIPTION
[0094] Referring to FIG. 1, a handheld instrument 100 for
image-guided intracardiac procedures includes a distal imaging
system 200 and a tool 300, such as a tissue removal tool, a
catheter, a tissue gripping device, a mitral valve clip, or another
type of tool. The imaging system 200, sometimes referred to as a
cardioscope, includes an optically clear window 110 within which a
camera 112 or optical fiber and an illumination device (not shown)
are disposed. The camera 112 and illumination device are controlled
by electronics 114, which can be in a handle 116 of the instrument
100 or external to the instrument. The camera 112 and illumination
device in the cardioscope 200 enable the procedure site to be
imaged, for instance, to assist with detection of contact between a
distal face 118 of the optically clear window 110 (sometimes
referred to as an optical window) and the tissue, navigation to a
desired site, or visualization of the site during or after the
procedure.
[0095] The tool 300 passes through a tool channel 120 in the
optical window 110 and exits through the distal face 118 of the
optical window 110. The handle 116 enables a user, such as a
surgeon, to precisely control the location and operation of the
tool 300. The optical window 110 also includes a flushing channel
130 through which fluid, such as saline, can be provided. The fluid
can be used to flush the interface between the distal face 118 of
the optical window 110 and the tissue, or can be used for
diagnostic purposes, as discussed below.
Device Components
[0096] Blood is opaque to visible light. To image in a blood-filled
environment, such as a beating heart or a brain, using visible
light, blood can be excluded from the space between the imaging
device and the tissue being imaged. An optical window is a device
that creates an optically transparent pathway between an imaging
device, such as a camera or an optical fiber, and tissue. The
optical window described here is a device formed of a solid,
transparent polymer having a distal face that can conform to the
topology of the tissue, thus displacing blood from the interface
between the distal face and the tissue. As a result, an optically
clear path for imaging the tissue is created.
[0097] Referring to FIG. 2, the optical window 110 of the
cardioscope 200 is a solid window formed of a transparent,
compliant, biocompatible material, such as a polymer (e.g.,
silicone, silicone rubber, castable resins such as acrylic resins
or polyurethanes, or another polymer), glass, transparent crystals,
or another transparent, compliant material. The compliance of the
optical window 110 can be controlled by the thickness and
composition of the polymer and the conditions under which the
polymer is processed, such as the curing temperature. The
compliance of the optical window 110 helps facilitate contact with
and imaging of irregular surfaces, as discussed below, and further
helps to prevent damage to tissue. In the example of FIG. 2, the
optical window 110 acts as a structural support for the components
therein. In some examples, an optical window includes separate
structural components. The optical window 110 can be formed of a
material having a refractive index that is similar to the
refractive index of the flushing fluid or to the environment in
which the cardioscope 200 is to be deployed. In a specific example,
the optical window 110 is formed of optically clear silicone (QSil
216 or QSil218 RTV-2 silicone rubber, Quantum Silicones LLC,
Richmond, Va.) with a refractive index of about 1.4. The example of
FIG. 2 shows the optical window 110 disposed at the distal end of a
cardioscope. The optical window 110 can also be disposed on other
surgical devices, such as neuroendoscopes, as discussed further
below.
[0098] In the example of FIG. 2 the camera 112 and an illumination
device, such as a light-emitting diode (LED) or optical fiber, are
embedded within the solid material of the optical window 110. The
camera 112 can be, for instance, a charge-coupled device (CCD)
camera (e.g., a 5 mm diameter CCD camera) or a complementary
metal-oxide semiconductor (CMOS) camera (e.g., a 1 mm.times.1
mm.times.1 mm CMOS video camera (250.times.250 pixels, Naneye,
Awaiba, Inc., Funchal, Madeira, Portugal)). The illumination device
can be a light-emitting diode (LED) or an optical fiber, such as a
1.6 mm.times.1.6 mm LED (Cree Inc., Durham, NC). The camera 112 and
the illumination device can be connected to control electronics or
storage devices by way of a cable 202. The camera 112 is positioned
within the optical window 110 such that some or all of the distal
face 118 of the optical window 110 falls within the field of view
of the camera 112. The camera can have a large focal depth in order
to enable high resolution imaging. In some examples, the camera 112
and illumination device are inserted into an optical channel formed
in the optical window. In some examples, the camera 112 is a camera
on a chip, e.g., a 1 mm.sup.2 chip, with LED illumination. In some
examples, the lens systems of the camera 112 and illumination
device are designed to be focus-free such that a sharp image can be
obtained over a large depth of field.
[0099] The use of a CMOS camera can have advantages. For instance,
in a CMOS sensor, each pixel has its own charge-to-voltage
conversion, and the sensor often also includes amplifiers,
noise-correction, and digitization circuits, so that the chip
outputs digital bits. This lowers camera cost while providing
faster readout, lower power consumption, higher noise immunity and
a smaller system size.
[0100] The distal face 118 of the optical window 110 displaces
blood when pressed against tissue in a body cavity filled with an
opaque fluid, such as the beating heart or a blood-filled cavity in
the brain, thus enabling visualization of the interaction between
the tool inserted in the tool channel 120 and the tissue (e.g.,
cardiac tissue or brain tissue). The compliance of the optical
window 110 allows the distal face 118 of the optical window 110 to
conform to irregular surfaces, thus effectively displacing blood
from between the distal face 118 of the optical window 110 and the
tissue. For instance, when the instrument 100 is used for repair of
a paravulvular leak, the distal face 118 of the optical window 100
may come into contact with irregular tissue topography at the
junction between the valve and surrounding cardiac tissue. The
compliance of the optical window allows the distal face 118 of the
optical window 110 to conform to that irregular topography, thus
facilitating imaging and enabling precise control of the tool
300.
[0101] The tool channel 120 and the flushing channel 130 are
elongated holes formed in the solid optical window 110. In some
examples, due to the compliance of the material of the optical
window 110, when empty, the tool channel 120 and the flushing
channel 130 collapse onto themselves, forming a thin crack in the
solid material of the optical window 110. The thin crack only
minimally occludes the field of view of the camera 112, enabling
the camera to image all of the tissue in the field of view prior to
tool insertion into the tool channel 120. Referring to FIGS. 3A and
3B, in an example, a chicken breast 310 is manipulated by an
instrument having an optical window at its distal end. Prior to
tool insertion into the tool channel 120 (FIG. 3A), the tool
channel 120 and the flushing channel 130 are almost invisible in
the image acquired by the camera in the optical window, apparent as
only thin lines. When a tool 312 is inserted into the tool channel
120, the tool appears in the image (FIG. 3B), thus occluding a
portion of the field of view. In some examples, the tool channel
120 is filled with saline prior to tool insertion into the tool
channel 120.
[0102] In some examples, the distal opening of the flushing channel
130 is self-sealing, preventing exchange of material, such as air
or blood, between the interior of the flushing channel 130 and the
heart. In some examples, the distal opening of the tool channel 120
seals upon insertion of a tool into the tool channel 120. In some
examples, a seal, such as a silicone seal, is positioned at the
distal opening of the tool channel 120, the flushing channel 130,
or both, to seal the channels 120, 130 against material
exchange.
[0103] Liquid, such as saline, can be provided through the flushing
channel 130. Since the refractive index of silicone is close to the
refractive index of water, filling the flushing channel 130 of a
silicone optical window 110 causes the flushing channel 130 and the
optical window 110 to have substantially the same refractive index,
thus rendering the flushing channel almost transparent in images
acquired by the camera 112.
[0104] In some examples, saline can be used to clear away blood
trapped between the distal face 118 of the optical window 110 and
the cardiac tissue. Blood can sometimes become trapped between the
distal face 118 of the optical window 110 and the cardiac tissue
when operating on uneven surfaces, such as trabeculated tissue, or
when searching for a paravulvular leak at the junction between a
valve annulus and the frame of an implanted valve. Liquid can also
be provided through the flushing channel 130 to temporarily
displace blood in front of the distal face 118 of the optical
window 110 when the distal face 118 is not in contact with tissue.
A bolus of saline can be ejected, allowing temporary visualization
of structures located a short distance, such as a few mm, in front
of the distal face 118 and helping to facilitate safe, precise
navigation and avoidance of sensitive structures.
[0105] The optical window 110 can be fully sealed and internal
components fully encapsulated such that blood from the heart does
not leak into the channels 120, 130 or the camera 112 or other
optical components and so that the environment of the heart is not
exposed to air bubbles or non-sterile components in the optical
window 110.
[0106] A distal portion 204 of the tool channel 120 can have a
diameter that is closely matched with the outer diameter of the
tool to achieve a tight seal around the tool, e.g., to minimize
leakage of blood and air into and out of the tool channel 120. For
instance, distal portion 204 of the tool channel 120 can have a
diameter of about 1 mm, about 1.5 mm, about 2 mm, about 2.5 mm, or
another diameter that is matched with the diameter of the tool
300.
[0107] The compliance of the optical window 110 allows the optical
window 110 to deform to follow the shape of a tool inserted into
the tool channel 120 or to follow the shape of the optical
components.
[0108] In some examples, the tool channel 120 can be structured to
act as a steering mechanism that is able to be deformed to point in
a desired direction. For instance, the tool channel 120 can be
formed of two pre-curved concentric elastic tubes. Twisting the
internal tube can cause the optical window 110 to change shape to
the configuration prescribed by the twisting tubes. The
longitudinal extension of the tubes provides structural stability
to the optical window 110 along its longitudinal axis.
[0109] In some examples, a proximal portion 206 of the tool channel
120 can be lined with a tube 208, such as a rigid tube formed of a
biocompatible material, e.g., stainless steel, hard plastic, or
other polymeric materials such as polytetrafluoroetheylene (PTFE)
that can reduce friction between the surface of the tool channel
120 and the tool inserted therein, thus enabling precise control of
tool operation using small forces. For instance, the cutting depth
of a tissue removal tool can be precisely adjusted by application
of small forces. The inner diameter of the tube 208 can be the same
as or slightly larger than the diameter of the distal portion 204
of the tool channel 120. For instance, the tube 208 can have an
inner diameter of about 1.5 mm, about 2 mm, about 2.5 mm, about 3
mm, or another diameter. In some examples, the tube 208 can be
formed of a compliant material.
[0110] In a specific example, the tool is a tissue removal tool as
described below having an outer diameter of 2 mm, the distal
portion 312 of the tool channel 120 has a diameter of 1.9 mm, and
the tube 208 has an inner diameter of 2.15 mm.
[0111] The tube 208 can be positioned along the tool channel 120
proximal to the distal face 118 of the optical window 110 such that
the tube 208 does not occlude the field of view of the camera 112.
For instance, the distal end of the tube 208 can be located about 5
mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm,
about 11 mm, about 12 mm, about 13 mm, about 14 mm, about 15 mm, or
another distance from the distal face 118 of the optical window
110.
[0112] In some examples, a proximal portion 210 of the flushing
channel 130 can be lined with a tube 212, such as a rigid tube
formed of a biocompatible material, e.g., stainless steel. The tube
212 can be positioned along the flushing channel 130 proximal to
the distal face 118 of the optical window 110 such that the tube
212 does not occlude the field of view of the camera 112. The
distal end of the tube 212 in the flushing channel 130 can be
positioned closer to the distal face 118 of the optical window 110
than the distal end of the tube 208 in the tool channel 120. For
instance, the distal end of the tube 212 can be located about 3 mm,
about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9
mm, about 10 mm, or another distance from the distal face 118 of
the optical window. In some examples, the tube can be formed of a
compliant material.
[0113] FIGS. 4-7 show alternative examples of cardioscopes and
optical windows. Referring to FIG. 4, in a cardioscope 40, an
optical window 42 is mounted on a 3 mm diameter straight tube 44.
The cardioscope 40 includes a camera 46 on a chip having a field of
view 48 as shown and an LED light source 47. A tool channel 49
falls within the field of view 48 of the camera 46. The cardioscope
40 can be, for instance, mounted on the distal end of a catheter,
as discussed below. Referring to FIG. 5, a cardioscope 50 for
mounting on the distal end of a catheter includes structural
components 52 that constrain the position and angle of a camera 54
on a chip, an LED light source 55, and a tool channel 56. The outer
diameter of the structural components 52 can be, e.g., 7 mm and the
outer diameter of the tool channel 56 can be 3 mm. A field of view
58 of the camera 54 is not obstructed by the tool channel 56.
[0114] In the example of FIG. 6, a cardioscope 60 including an
optical window 62 is mounted on a structural component 64. The
structural component 64 includes holes 66 allowing the silicone of
the optical window 62 to penetrate therein, thus stabilizing the
optical window 62 on the structural component. The field of view 68
of a camera 69 is unobstructued due to the placement of a tube 67
in the proximal portion of a tool channel 65. The assembly of the
cardioscope 60 can be seen in FIGS. 7A-7C.
[0115] In some examples, the optical window 110 is formed by
molding. A mold, for instance a polymer mold, of the optical window
110, including the tool channel 120, the flushing channel 130, and
a hollow for the camera 112 and illumination device, can be
created, for instance, by three-dimensional printing, injection
molding, extrusion, or other molding processes. The material of the
optical window 110 is a transparent and optically clear polymeric
material, e.g., silicone or silicone rubber (e.g., QSil 216 or QSil
218, Quantum Silicones), is cast into the mold and allowed to cure.
In some cases the optical window 110 is mounted on a structural
component, which can be created, for instance, by three-dimensional
printing, injection molding, or other processes.
Geometry of the Optical Window
[0116] The geometry of the optical window 110 can enable the camera
112 to achieve a large field of view of the tissue, for instance,
enabling visualization of tissue before, during, and after a
procedure, and enabling visualization of the position and depth of
the tool relative to the tissue before, during, and after the
procedure. In addition, the geometry of the optical window 110 can
facilitate operation of the tool, for instance, by providing a
suitable angle of contact between the tool and the tissue or by
accommodating an angle of approach for the tool that is suitable
for a given procedure. In some examples, an angle of contact
between the tool and the surface normal of the tissue is less than
90.degree., e.g., about 45.degree..
[0117] The geometry of the optical window 110 can depend on where
the instrument 100 is to be deployed, the nature of the tool to be
used with the instrument, or both. For instance, a target angle of
approach for a tissue removal tool may be different than a target
angle of approach for a catheter, and a dedicated optical window
110 with a geometry to achieve the appropriate angle of approach
may be designed for each tool.
[0118] The geometry of the optical window 110 can depend on the
wavelength of light provided by the illumination source. For
instance, the index of refraction of the material of the optical
window (e.g., silicone or silicone rubber) and of the blood can
vary based on the wavelength. The geometry of the optical window
110 can thus be specific to the wavelength of light, such as
visible light or infrared light, in order to, e.g., enable the
camera 112 to achieve a large field of view. Because blood is
transparent to infrared wavelengths, imaging with infrared light
can enable visualization of structures ahead of the distal face of
the optical window even in the presence of blood. For instance,
imaging with infrared light can enable a user to navigate a
catheter through a blood-filled heart while avoiding coming near
sensitive structures of the heart.
[0119] Referring to FIG. 8A, in some examples, the optical window
110 has a convex, hemispherical distal face 118a. A hemispherical
distal face 118a can facilitate the displacement of blood the
interface between the distal face 118a and tissue during tissue
contact. A circular field of view can be achieved by pressing the
hemispherical distal face 118a into tissue. In addition, with a
hemispherical distal face 118a, the tool 300 can be positioned off
center, for instance, to achieve an angle of tool-tissue contact of
less than 90.degree., such as an angle of about 45.degree..
Referring to FIG. 8B, in some examples, the optical window 110 has
a convex distal face 118b, e.g., with surface curvature in only a
single axis or in multiple axes. In some examples, the optical
window has a concave distal face (not shown).
[0120] Referring to FIG. 8C, in some examples, the optical window
110 has a planar distal face 118c. The planar distal face 118c
provides a large field of view at low contact force with the tissue
and can effectively evacuate blood from in front of the distal face
118c when in contact with tissue. The planar distal face 118c also
enables the tool 300 to be positioned within the field of view of
the camera 112 and allows the tool 300 to be angled to achieve a
desired angle of approach.
[0121] Referring to FIG. 8D, in some examples, the optical window
110 has a distal face 118d with an angled planar surface. An angled
planar surface is a surface whose normal is disposed at an angle
greater than 0.degree. relative to a longitudinal axis of the
optical window 110. The angled planar distal face 118d provides a
large field of view at low contact force with the tissue and can
effectively evacuate blood from in front of the distal face 118d
when in contact with tissue. The angled planar distal face 118d
also enables the tool 300 to be positioned within the field of view
of the camera 112 and allows the tool 300 to be positioned to
achieve a desired angle of approach. In addition, with the angled
planar distal face 118d, a desired angle of tool-tissue contact can
be achieved. In some examples, the angled planar distal face 118d
can be angled such that the normal to the distal face 118d is at an
angle .PHI. of between about 20-25.degree. from the longitudinal
axis of the optical window 110, such as an angle of about
20.degree., about 21.degree., about 22.degree., about 23.degree.,
about 24.degree., about 25.degree., or another angle. Selection of
an appropriate angle .PHI., for instance, based on anatomy in the
target region of the heart, can enable contact to be achieved
between the angled planar distal face 118d and the tissue over the
entire target region.
[0122] The diameter of the optical window 110 can taper from a
large diameter d.sub.1 to a smaller diameter d.sub.2 within a
distal region 304 of the optical window 110. The large diameter
d.sub.1 can be, for instance, between about 1 mm and about 20 mm,
or between about 3 mm and about 6 mm, e.g., about 3 mm, about 4 mm,
about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about
10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, about 15
mm, about 16 mm, about 17 mm, about 18 mm, about 19 mm, about 20
mm, or another diameter. The smaller diameter d.sub.2 can be, for
instance, between about 2 mm and about 15 mm, e.g., about 2 mm,
about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8
mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13 mm,
about 14 mm, about 15 mm, or another diameter. A proximal region
306 of the optical window 110 having a constant diameter d.sub.1
can extend from the end of the distal region 304 to the proximal
end of the optical window 112. For instance, the optical window 110
can have the large diameter d.sub.1 at the position where the
optical window 110 passes through the heart wall. The camera 112
can be positioned within the large diameter proximal region 306,
enabling a large field of view to be achieved. The smaller diameter
at the distal end of the optical window 110 allows the distal face
118 of the optical window 110 to slide smoothly over tissue with
little trapping of blood between the tissue and the distal face
110.
[0123] In some examples, the tool channel 120 is positioned in the
center of the optical window 110. In some examples, the tool
channel 120 is offset relative to the center of the optical window
110. The tool channel 120 can be aligned with the optical window
110 or can be positioned at an angle relative to the longitudinal
axis of the optical window 110. For instance, an angle .theta.
between the longitudinal axis of the tool channel 120 and the
longitudinal axis of the optical window 110 can be between about
0.degree. and about 90.degree., e.g., about 0.degree., about
5.degree., about 10.degree., about 15.degree., about 20.degree.,
about 25.degree., about 30.degree., about 35.degree., about
40.degree., about 45.degree., about 50.degree., about 55.degree.,
about 60.degree., about 65.degree., about 70.degree., about
75.degree., about 80.degree., about 85.degree., about 90.degree.,
or another angle. The tool channel 120 can be positioned at an
angle to the camera 112, e.g., to enable visualization of a desired
field of view. For instance, an angle .alpha. between the
longitudinal axis of the camera 112 and the longitudinal axis of
the tool channel 120 can be between about 0.degree. and about
30.degree., e.g., about 0.degree., about 5.degree., about
8.degree., about 10.degree., about 15.degree., about 20.degree.,
about 25.degree., about 30.degree., or another angle. The
positioning of the tool channel 120 within the optical window 110
determines the angle of contact between the tool 300 and the
tissue. The angle of contact .beta. between the tool and the
surface normal of the tissue can be less than 90.degree., e.g.,
about 0.degree., about 10.degree., about 20.degree., about
30.degree., about 40.degree., about 45.degree., about 50.degree.,
about 60.degree., about 70.degree., about 80.degree., about
85.degree., or another angle.
[0124] The positioning and orientation of the tool channel 120
within the optical window 110 can depend on, e.g., the type or size
of the tool 300 to be inserted into the tool channel 120, the
environment in which the tool 300 is intended to operate, or other
factors. The placement of the tool channel 120 can also be selected
to achieve a desired position of the distal tip of the tool 300 in
the field of view of the camera 112. In an example, the tool 300 is
a tissue removal tool (discussed further below) for removing tissue
in corners under a heart valve, such as in the infundibulum below
the pulmonary valve. To enable the distal tip of the tool 300 to
reach into the narrow corners, the tool channel 120 can be
positioned off center in the optical window 110. In addition, to
enable visualization of the tissue cutting procedure and
observation of the depth of the cut, the camera 112 and the tool
channel 120 can be angled toward each other.
[0125] In the specific example of FIG. 8D, the tool 300 is a tissue
removal tool. The large diameter d.sub.1 of the optical window 110
is 14 mm. The camera 112 is rotated by 6.degree. and the tool
channel 120 is rotated by 2.degree. to achieve an angle a between
the camera 112 and the tool channel 120 of 8.degree.. The angle
.PHI. between the normal to the distal face 118d and the
longitudinal axis of the optical window 110 is 22.degree.. With
this geometry, the angle of contact between the tool 300 and the
surface normal of the tissue is 20.degree. and the camera achieves
a field of view of 7.5.times.10 mm.
[0126] Referring to FIGS. 9A and 9B, in some examples, multiple
cameras or multiple tool channels can be positioned within the
optical window, e.g., in order to achieve tool triangulation or
multiple camera viewing angles. In the example of FIG. 9A, two
cameras 112a, 112b are positioned within the optical window 110,
thus providing a broad field of view in front of the distal face
118 of the optical window 110 and to the side of the optical window
110. In the example of FIG. 9B, two tool channels 120a, 120b are
formed through the optical window and curved such that tools
inserted through the tool channels 120a, 120b can work
cooperatively at a single surgical site. The camera 112 in the
example of FIG. 9B is positioned and angled such that the distal
opening of each tool channel 120a, 120b and the meeting point of
the tools inserted therethrough both fall within the field of view
of the camera 112.
Uses of the Cardioscope with a Tissue Removal Tool
[0127] In some examples, the tool that is inserted through the tool
channel 120 of the optical window 110 of the instrument 100 is a
tissue removal tool. The tissue removal tool can be used to remove
cardiac tissue from the interior of the heart to treat, e.g.,
congenital heart defects such as pulmonary stenosis. For instance,
referring to FIG. 10, an instrument 400 including a tissue removal
tool can be inserted through the free wall 402 of the right
ventricle 404 and used to remove excess tissue in the outflow tract
406 below the pulmonary valve 408, in a region known as the
infundibulum. Removal of excess tissue in the infundibulum can
relieve obstruction of the valve or outflow tract from the right
ventricle into the pulmonary artery to treat pulmonary stenosis.
The optical window enables visualization of the positioning of the
tissue removal tool before and during contact with the tissue in
the infundibulum and enables real time imaging as the excess tissue
is removed by the tissue removal tool.
[0128] Referring to FIGS. 11A-11C, an example of a tissue removal
tool 500 has a diameter of 2 mm, although tissue removal tools with
other dimensions are also possible. The tissue removal tool 500
includes a stator 502 and a rotor 504 attached by an integrated
bearing 506. The rotor 504 is attached to an inner rotating tube
508, e.g., by laser welding or another attachment technique. The
rotating tube is driven by a motor, such as a motor 138 shown in
FIG. 1. The stator is attached to a stationary outer tube 510,
e.g., by a snap fit connection or another attachment technique. A
vacuum pump (not shown) is used to aspirate tissue debris through
the hollow central channel of the rotating tube 508, as shown by
arrows 512. To avoid clogging of the tissue removal tool 500 and to
reduce blood loss, the cutting interface can be irrigated, e.g.,
with heparinized saline, provided through a gap 514 between the
outer surface of the rotating tube 508 and the inner surface of the
stationary outer tube 510.
[0129] The stator 502 in this example includes two cutting windows
516a, 516b. Efficient tissue removal occurs when the tissue removal
tool 500 is oriented such that tissue presses against one of the
cutting windows 516a, 516b. Teeth 518 of the rotor 504 mesh with
teeth 520 of the stator 502 to slice the tissue. Debris is
transported away from the cutting interface through the hollow
central channel of the rotating tube 508.
[0130] The tissue removal tool 500 is operated by sliding a distal
tip 522 of the tissue removal tool 500 across the tissue at an
angle of less than 90.degree. between the axis of the tissue
removal tool 500 and the plane of the tissue surface. For instance,
the tissue removal tool 500 can be held at a 45.degree. angle to
the tissue surface. By inserting the tissue removal tool 500 into
the optical window 110 as described above, the angle between the
tissue removal tool 500 and the tissue surface can be controlled
such that a desired angle is achieved.
[0131] During tissue removal, the depth of the cut by the tissue
removal tool 500 during each of a series of passes over the tissue
can be limited to avoid gouging the tissue or damaging the tissue
removal tool 500. Heart tissue motion over the cardiac cycle varies
by location, but can be up to a centimeter. Consequently, the depth
of the cut into cardiac tissue cannot be accurately controlled
simply by rigid positioning of the tissue removal tool. Integration
of the tissue removal tool 500 into the optical window 110 enables
precise control of the cutting depth even in situations where the
tissue is not stationary, such as in a beating heart. The distal
face 118 of the optical window 110 acts as a depth control device,
e.g., similar to a sole plate of a woodworking router. The distal
face 118 of the optical window 110 is pressed against the tissue to
establish stable contact between the optical window and the tissue.
The distal tip of the tissue removal tool 500 is extended out from
the distal face 118 of the optical window 110 by a specific and
controlled amount. The optical window 110 maintains continuous
contact with tissue 500 even as the tissue moves, e.g., even as the
heart beats, thus keeping the depth of the cut stabilized at a
constant value. For instance, by pressing lightly into the tissue,
contact can be maintained over the cardiac cycle. The contact force
will vary over the cardiac cycle, but is small enough to not cause
any damage, in part because the contact force is applied over the
compliant surface of the optical window 110. If the tool is rigid,
such as in the case of the instrument 100, the tissue is locally
immobilized. When the cardioscope is used at the distal tip of a
flexible instrument, such as a catheter, the instrument flexes over
the cardiac cycle.
[0132] In some examples, one or more marks can be made on the tool
(e.g., the tissue removal tool 500) to enable a viewer of an image
to determine the depth of penetration of the tool into the
tissue.
[0133] Referring also to FIG. 1, the extension of the distal tip
522 of the tissue removal tool 500 can be controlled by a trigger
142 in the handle 116 of the instrument 100. To achieve a tool
extension resolution of a fraction of a millimeter, the trigger 142
is operable in an on-off fashion. When the trigger 142 is pulled,
the distal tip 522 of the tissue removal tool 500 is retracted into
the optical window 110. When the trigger 142 is released, a spring
extends the distal tip 522 of the tissue removal tool by a discrete
distance. In some examples, the discrete distance by which the
distal tip 522 is advanced each time the trigger 142 is released
can be set, e.g., digitally or mechanically, such as by an
adjusting screw. The trigger 142 can be sufficiently responsive and
the handle 116 sufficiently lightweight to allow a user to operate
the instrument 100 with just one hand. Once contact is established
between the tool and the tissue, the trigger 142 allows for
extension of the tool relative to the instrument (e.g., the
instrument 100). In some examples, trigger release causes tool
extension and pulling the trigger retracts the tool. In some
examples, trigger release retracts the tool and pulling the trigger
causes tool extension.
[0134] In some examples, the tissue removal tool 500 can be
fabricated using a metal MEMS (microelectromechanical system)
fabrication process in which 25 .mu.m thick layers of structural
metal, such as NiCo, and sacrificial metal, such as copper, are
deposited by photolithographic electrodeposition. In some examples,
the handle 116 can be fabricated by molding, three-dimensional
printing, or another fabrication process. The handle 116 can be
made of a lightweight, rigid, biocompatible plastic such as
acrylonitrile butadiene styrene (ABS) plastic. In some embodiments,
the tool and optical window are designed to be disposable. In some
embodiments, the tool is designed to be sterilized and reused with
only the optical window being disposable. In some embodiments, the
tool and optical window are both designed to be sterilized and
reused. The optical window can be easily sterilized when the design
of the optical window is such that the components of the optical
window are encapsulated therein and the optical window is formed of
a material with high temperature tolerance, such as silicone. The
handle can be made disposable or reusable.
[0135] Referring to FIG. 12, in an example of a procedure for using
an optical window with a tissue removal tool, an incision is made
in the right ventricular free wall of the heart (600). An
instrument including an optical window at its distal end is
inserted through the incision (602) and navigated to the
infundibulum via image guidance from the camera in the optical
window (604). For instance, imaging can indicate the closeness of
the distal tip of the optical window to the target tissue and can
indicate when contact has been made between the optical window and
the target tissue. The instrument is brought into contact with the
tissue at the target location (606), guided by imaging from the
optical window. During the positioning, saline can be ejected from
the flushing port (608) as necessary to provide a clear view, such
as to provide a temporary view of the anatomy of the tissue prior
to contact or to clear any trapped blood after contact.
[0136] When the optical window is positioned at the desired
location on the target tissue, a tissue removal tool is advanced
through the instrument channel of the optical window (610). While
the tissue removal tool can be advanced prior to positioning of the
optical window, the tissue removal tool would partially occlude the
field of view of the camera in the optical window, thus making
positioning of the optical window more challenging. The tissue
removal tool is further advanced beyond the distal face of the
optical window (612) into the tissue and tissue is removed as
appropriate (614). The cutting depth of the tissue removal tool
during tissue removal is controlled by the contact between the
distal face of the optical window and the tissue such that, even as
the heart tissue moves throughout the cardiac cycle, the cuts by
the tissue removal tool remain at a constant depth.
[0137] When the procedure is finished, the tissue removal tool is
retracted out of the optical window (616) so as not to block the
field of view, and images are acquired of the tissue following the
procedure, if desired (618). Post-procedure images can be used, for
instance, to confirm that the procedure has been completed
correctly, to monitor for abnormal bleeding, or for other
purposes.
Uses of the Cardioscope with a Catheter
[0138] Cardioscopes can be used to provide image guidance and
positioning and depth control for various catheter-based beating
heart procedures, e.g., valve repair or replacement, closure of
openings between the two atria of the heart, tissue removal, tissue
ablation, the placement or removal of various diagnostic or
therapeutic devices, biopsy, local injection, in situ imaging such
as ultrasonic, infrared, or optical coherence tomography (OCT)
imaging, or other procedures. The dimensions and geometry of the
optical windows can vary based on characteristics of the device and
metrics of the procedure. For instance, a larger version of an
optical window can be disposed at the distal tip of an ablation
catheter having a diameter of about 5-6 mm.
[0139] Referring to FIG. 13, a cardioscope 90 is provided at the
distal tip of a robotic catheter 92 to provide imaging capabilities
for guiding the navigation and positioning of the catheter and for
guiding and controlling the operation of a tool inserted through
the tool channel of the cardioscope 90.
[0140] Referring to FIG. 14, in some examples, a catheter 150 with
a distal cardioscope 152 can be used for the detection and repair
of leaks around a replacement valve 154 in a heart 156, such as an
aortic paravalvular leak (PVL). The catheter 150, including the
distal cardioscope 152, is inserted into the heart 156 through an
introducer sheath (not shown) placed through the apex of the heart
and navigated through the left ventricle and to the periphery of
the aortic annulus. The optical window of the cardioscope 152
enables visualization of the positioning of the distal tip of the
catheter relative to the valve 154 and possibly visualization of
the leak itself. For each PVL, a wire 158 is passed through the
leak and an occluder device (not shown), such as an Amplatzer.RTM.
ductal or vascular occluder, is deployed along the wire 158 to
repair the PVL. The distal cardioscope 152 enables the catheter 150
to be precisely positioned at the area of the leak, enables
visualization of the replacement valve and the surrounding tissue,
and enables visualization and control of the placement of the wire
and the occlude device. The visualization and control provided by
the distal cardioscope 152 enables the PVL repair procedure to take
place in a beating heart.
[0141] In some examples, cardioscopes as described herein can be
deployed to help in identification of the location of a PVL. A
bolus of saline, much smaller than the field of view of the camera
in the optical window, can be ejected from the flushing channel of
the optical window into the space between the distal face of the
optical window and the tissue. If there is no leak, the bolus of
saline dissipates uniformly in front of the distal face of the
optical window. If, however, a leak is nearby, the bolus of saline
is rapidly and non-uniformly dispersed away from the source of the
leak. The dispersal of the bolus of saline can be visualized and
used to determine the likely location of a PVL, as well as to
qualitatively or quantitatively characterize blood flow patterns in
the heart. In some examples, a bolus of a colored material, such as
methylene blue, can be ejected from the flushing channel in order
to assist with visualization of blood flow patterns.
[0142] In another example, of the catheter 150 is an ablation
catheter and the cardioscope 152 provides image guidance,
visualization of the ablation site, and control of the depth of the
catheter tip.
[0143] Referring to FIG. 15, in another example, a catheter 160
with a distal cardioscope 162 can be used for image-guided
manipulation of a mitral leaflet 164. In the example of FIG. 15,
the catheter 160 is a two-handed robotic catheter enabling bimanual
tissue manipulation. In some examples, the catheter 162 can be a
single branch catheter.
[0144] Referring to FIGS. 16A and 16B, in another example, a
cardioscope 200 is integrated with a mitral valve clip 32, and a
tissue gripping device 30, or both, to enable image-guided valve
repair. In cardiac valve repair, a tissue gripping device such as
the tissue gripping device 30 is used to grip the valve leaflet,
and the tissue gripping device 30 is then moved along the leaflet
to the repair location. At the repair location, a clip such as the
mitral valve clip 32 can be placed or a suture inserted to repair
damage to the leaflet. With cardioscopic imaging integrated into
the tissue gripping device 30, the positioning of the tissue
gripping device 30 on the valve leaflet can be visualized and the
tissue gripping device 30 can be precisely moved to the repair
location. The damage to the leaflet can also be visualized.
Cardioscopic imaging integrated into the mitral valve clip 32 can
enable precise positioning of the mitral valve clip 32 and
subsequent visual monitoring of the healing progress of the
leaflet, e.g., to view how much and what tissue is grasped.
[0145] Referring to FIG. 17, in some examples, the distal face 118
of the optical window 110 can be marked with one or more fiducial
markings 70 that can be used to measure distances on tissue, such
as the diameter of a PVL, the distance from the tip of a tissue
gripping device to the edge of a leaflet, the size of an area of
removed tissue, or other distances of interest.
[0146] In some examples, no fiducial markings are used. The camera
images can be calibrated for the field of view through the distal
face and precise dimension measurements can be performed during or
after surgery using the images. For instance, a ruler or grid can
be overlaid on the digital image to perform a measurement visually,
or an automated measurement approach can be used. An operator, such
as a surgeon or an analyst, can manually or automatically process
the image, for instance by drawing a line or rastering the image,
to record information during or after surgery. The images can be
recorded in a standard format, such as a dicom format, to
facilitate post processing of the images.
Alternative Optical Window Structures
[0147] Referring to FIG. 18, an alternative optical window 700
includes a transparent, compliant, hollow polymer bulb 702 that is
curved, such as into a hemispherical shape. For instance, the bulb
702 can be formed of silicone (e.g., available from NuSil
Technology), silicone rubber, or another transparent, compliant,
biocompatible polymer. The compliance of the bulb 702 can be
controlled by the thickness and composition of the polymer and the
conditions under which the polymer is processed, such as the curing
temperature. The compliance of the bulb 702 allows the bulb 702 to
conform to irregular surfaces, thus effectively displacing blood
from between the outer surface of the bulb 702 and the tissue. An
interior 704 of the bulb 702 is filled with a clear, biocompatible
liquid, such as saline.
[0148] The bulb 702 is disposed at a distal end of a device 703,
such as a catheter or instrument port. The device 703 includes
optical components, such as a camera, a camera on a chip, an
optical fiber 706, or an illumination device, and a tool channel
710 to receive a tool. The tool channel 710 can be a structurally
robust tube, such as a polyimide tube reinforced with wire
braiding, to support the passage of pre-curved tubes and wires
therethrough, as described below. In some examples, the optical
components, the tool channel 710, or both, can be glued to the
interior of the device 703, for instance using medical grade epoxy.
An alignment disk 705 connects the bulb 702 to the device 703 and
acts as a structural and watertight connection between the interior
of the device 703 and the interior 704 of the bulb 702. The
alignment disk 705 can include holes for mating with the distal
ends of the tool channel 710 and the optical fiber 706.
[0149] When the optical components of the device 703 include an
optical fiber, the distal end of the optical fiber 706, which can
include, for instance, a lens assembly, is exposed to the
fluid-filled interior 704 of the bulb 702. In some examples, the
optical fiber 706 can be press fit into the corresponding hole in
the alignment disk 705 through one or more gaskets to provide a
seal between the optical fiber 706 and the alignment disk 705. In
some examples, a collar (not shown) can be attached to the distal
end of the optical fiber 706, for instance, by gluing with a
medical grade epoxy. The collar can be attached to the alignment
disk 705 with fasteners to provide a structurally robust connection
between the optical fiber 706 and the alignment disk 705.
[0150] The tool channel 710 in the device 703 does not extend into
the interior 704 of the bulb 702. Thus, the field of view of the
optical fiber 706 is unobstructed prior to introduction of a tool
or other component through the tool channel and into the interior
704 of the bulb 702. A tool or other component inserted through the
tool channel 710 can be steered to a desired contact point on the
bulb 702, e.g., based on a position of the bulb relative to a
target region of tissue. The tool can then pierce the bulb at the
contact point and exit the bulb 702, contacting the target region
of tissue. When the tool is later retracted inside the bulb 702,
the hole in the bulb will seal itself due to the compliance of the
polymer forming the bulb 702. A small flow rate of saline or other
clear, biocompatible liquid, can be used subsequent to piercing of
the bulb 702 or retraction of the tool to flush out any blood that
penetrated to the interior of the bulb 702. In some examples, a
tool can pierce the bulb at each of multiple contact points, the
hole at each contact point sealing when the tool is retracted. The
ability to steer a tool within the bulb 702 and to cause a tool to
exit the bulb 702 at multiple contact points can reduce or
eliminate the sliding of the bulb 702 along the tissue to achieve
alignment between the tool and the target region of tissue. For
instance, the tool can exit the bulb 702 at a first contact point
to perform a procedure at a first location within the heart, then
be retracted within the bulb 702 and exit the bulb 702 again at a
second location to perform a procedure at a second, nearby location
within the heart.
[0151] In some examples, a pre-curved steering tube 714 can be used
to guide the tool within the interior of the bulb 702, e.g., to
achieve alignment with a target region of tissue. The tube 714 can
be a thin-walled metal or polymer tube, such as a NiTi or stainless
steel tube, inserted through the tool channel 710 of the device
703. A proximal length 716 of the tube 714 is straight. A distal
length 718 of the tube (e.g., the distal 5 mm) is pre-curved, such
as the distal region of the tube extending beyond the alignment
disk 705. When a tool is inserted through the tube 714, the tool
will be guided to a position along the bulb 702 at which the curved
distal length 718 of the tube 714 points. The tube 714 can be
rotated within the tool channel 710 to point at a desired point on
the bulb 702. For instance, FIG. 18 shows the tube 714 curved to
point toward a position near the center of the bulb 702. FIG. 18
also shows an alternate orientation 712 in which the tube 714 has
been rotated to point toward a position near the edge of the bulb
702.
[0152] In some examples, for instance, to achieve more precise
steering or a sharper curvature within the interior of the bulb
702, a guide wire 720, such as a pre-curved guide wire, can be
inserted into the tube 714. The guide wire 720 can control more
precisely the point at which a tool inserted through the tube 714
will contact the bulb 702. For instance, the guide wire 720 can be
oriented to either enhance or reduce the off-axis angle of the
curved distal length 718 of the tube 714. Once the guide wire 720
is positioned properly, the tool can be passed along the guide wire
720 to its point of exit from the bulb 702.
[0153] In one example, when locating a paravalvular leak (PVL), the
tube 714 can be oriented to point in the general direction of the
PVL, and the guide wire 720 can be advanced through the tube 714
and steered to the specific location of the PVL, using image
guidance provided by the camera 706. An occlusion device delivery
catheter can then be passed through the tube 714 and along the wire
to close the PVL.
[0154] Referring to FIG. 19, in some examples, seals can be
incorporated into the bulb 702 by partially or fully pre-cutting a
pattern, such as a pattern of crosshairs 80, into the bulb 702. The
presence of a pattern of crosshairs 80 can enhance tool steering
within the bulb 702 to the set of discrete points designated by the
pattern of crosshairs 80. The linear cuts of the crosshairs 80 can
be self-sealing cracks that fold open to allow passage of a tool
when the tool is pressed against the crack, and that re-seal when
the tool is removed. The pre-cutting of a pattern of crosshairs 80
into the bulb 702 can help to address the situation in which the
stiffness or tip geometry of the guide wire 720 or tool is
insufficient to pierce the bulb 702. The pattern of crosshairs 80
can also serve as a set of fiducial distance markers.
[0155] In some examples, a small initial hole can be generated at
the desired point on the bulb 702, for instance, using a radio
frequency (RF) ablation wire, for instance, to help address the
situation in which the stiffness or tip geometry of the guide wire
720 or tool is insufficient to pierce the bulb 702. In some
examples, a seal can be constructed in the bulb 702 by pre-cutting
larger crossed lines, similar to the seal in an introducer sheath,
for instance, to help with the penetration of a tool too large to
pierce the bulb 702. These same piercing and sealing features can
be used in any of the compliant optical windows described
herein.
[0156] Referring to FIGS. 20A-20C, an alternative optical window
750 includes an expandable bulb 752 disposed at a distal end of a
device, such as a catheter or an instrument port. Once the device
is positioned at the procedure site, the expandable bulb 752 can be
inflated, e.g., by filling the interior of the bulb 752 with a
clear liquid such as saline or another clear, biocompatible liquid
provided through a channel 753. In some examples, a continuous flow
of liquid is not used with the expandable bulb 752.
[0157] An optically clear tube 760 forms a tool channel within the
expandable bulb 752 through which a surgical tool can be inserted.
The use of an optically clear tube to define the tool channel
prevents the liquid filling the expandable bulb 752 from entering
into the tool channel. A camera 762 and an illumination device 764
are positioned inside the expandable bulb 752 such that some or all
of a distal face 765 of the expandable bulb 752 falls within the
field of view of the camera 762.
[0158] In some examples, the camera 762 can be moveable within the
expandable bulb 752. In some cases, as shown in FIG. 20A, the
camera 762 can be located in a retractable tube 766 that can allow
the camera to be positioned in a retracted position to allow a
general view, e.g., of the surgical site, and to be advanced toward
the distal face 765 of the expandable bulb 752 in order to enable
high resolution imaging of specific areas of the surgical site. In
some cases, as shown in FIG. 20B, the camera 762 can be disposed
inside a curved tube 768, such as a nickel titanium (NiTi) tube,
which can be rotated in order to enable the camera 752 to image
different areas. In some examples, the illumination device 764 can
be moveable within the expandable bulb 752. In some examples, the
camera, the illumination device, or both can have a fixed position.
For instance, the camera, the illumination device, or both can be
inserted into and sealed within an optical channel formed within
the expandable bulb 752.
[0159] With the expandable bulb 752, the diameter of the device can
be reduced, thus allowing the device to be used in applications for
which a smaller device is appropriate. For instance, the outer
diameter of the bulb 752 along the cross section A-A can be less
than about 6 mm, such as about 4 mm, about 4.5 mm, about 5 mm,
about 5.5 mm, or another diameter. The expandable portion of the
bulb can expand to a diameter greater than about 8 mm, such as
about 8 mm, about 9 mm, about 10 mm, or another diameter. Referring
to FIG. 21, within this diameter, the expandable bulb can be sized
to fit multiple channels and an imaging system. For instance, in
the example of FIG. 21, the expandable bulb 752 is sized to fit a
camera 762, three channels 770a, 770b, 770c, and multiple optical
fibers 771 for illumination. A specific example of the dimensions
of the channels 770a, 770b, 770c is given in FIG. 21. More
generally, the channels can have an inner diameter of between about
1 mm and about 3 mm, such as about 1 mm, about 1.5 mm, about 2 mm,
about 2.5 mm, about 3 mm, or another diameter. The expandable bulb
752 can be formed of an optically clear, flexible, biocompatible
material, such as a clear, low durometer thermoplastic
polyurethane.
Optical Windows used with Neuroendoscopes
[0160] In some examples, the optical windows described here can be
used in conjunction with a handheld neuroendoscope for image-guided
neurosurgical procedures. Referring to FIGS. 22A and 22B, a
handheld multi-port neuroendoscope 850 for image-guided
neurosurgical procedures includes a distal imaging system 852
(sometimes also called a distal port) and a lateral imaging system
854 (sometimes also called a lateral port). The distal imaging
system 852 includes an optically clear window 858 within which one
or more cameras 860 and one or more light sources 862 are disposed.
One or more channels are formed through the optical window 858. In
the example of FIGS. 22A and 22B, a single tool channel 864 and two
flushing channels 866, 868 are formed through the optical window
858. The lateral imaging system 854 also includes an optically
clear window 870 within which one or more cameras 872 and one or
more light sources 874 are disposed. One or more channels are
formed through the optical window 870. In the example of FIGS. 22A
and 22B, a single tool channel 876 is formed through the optical
window 870.
[0161] The distal and lateral imaging systems 852, 854,
respectively, enable the site of the neurosurgical procedure to be
imaged, for instance, to assist in navigation of a tool to a
desired site or visualization of the site before, during, or after
the procedure. The ability to utilize one or both of a side channel
(e.g., the side tool channel 876 or a side flushing channel) and a
distal channel (e.g., the distal tool channel 864 or the distal
flushing channels 866, 868) enables flexibility to access multiple
surgical sites concurrently or to access the sample surgical site
from different angles. In some examples, the neuroendoscope 850 can
be used for procedures such as colloid cyst resection combined with
septostomy. In some examples, the neuroendoscope 850 can be used
for treating multiloculated hydrocephalus, where the side tool
channel 876 enables the lysis of intraventricular adhesions that
may be difficult to fenestrate through the distal tool channel
864.
[0162] The incorporation of multiple optical windows can enable
multi-directional imaging and tool deployment. For instance, a
lateral port can be useful so that a user can avoid pivoting the
neuroendoscope to access a surgical site. In a specific procedure,
a lateral port can be used to perform a septostomy with minimal
pivoting of the instrument shaft. In another specific example, a
lateral port can be used to enable multiplanar fenestration of the
fibrous septae, which cannot generally be accessed easily by the
tip port.
[0163] The optical windows 858, 870 have generally the
characteristics described above with respect to the optical window
110. The optical windows 858, 870 can be formed of a solid,
transparent material having a face that can conform to the topology
of the tissue at the surgical site, thus displacing blood from the
interface between the face of the optical window and the tissue at
the surgical site and creating an optically clear path for imaging
the tissue. In some examples, the optical windows 858, 870 can be
formed of a transparent, compliant, biocompatible material, such as
a polymer, glass, transparent crystals, or another transparent,
compliant polymer. The optical windows 858, 870 can be formed of a
material having a refractive index similar to the refractive index
of cerebrospinal fluid, which is 1.33, in order to reduce
distortion. For instance, the optical window can be formed of
optically clear silicone (QSil 216 or QSil 218, Quantum
Silicones).
[0164] In some examples, the distal optical window 858 and the
lateral optical window 870 can have different thicknesses, e.g., in
order to satisfy different design criteria for the two positions,
in order to be functional for different uses, or for other reasons.
For instance, the lateral optical window 870 can be designed to be
flush with the outer surface of the neuroendoscope 850 so that no
protrusions are present along the outer surface, e.g., the lateral
optical window 870 can have a thickness of about 1 mm, about 2 mm,
or another thickness, and can be molded to be flush with the
surface. The distal optical window 858 can be thicker than the
lateral optical window, e.g., about 3 mm thick, about 4 mm thick,
about 5 mm thick, about 6 mm thick, or another thickness, in order
to enable visualization of tools inserted into the tool channel 864
or to enable safe contact between the optical window 858 or tools
and tissue at the surgical site.
[0165] In the example of FIGS. 22A and 22B, each optical window
858, 870 has a single tool channel formed therethrough. In some
examples, multiple tool channels can be formed through each optical
window, such as two tool channels, three tool channels, four tool
channels, or another number of tool channels. Multiple tool
channels can be useful, e.g., for complex surgical procedures
involving the concurrent use of multiple tools, e.g., for colloid
cyst dissection. The optical windows 858, 870 can include one or
more flushing channels or can include no flushing channels. The
channels can all be equally sized or each channel can have a
different size or configuration. In some examples, a single tool
channel can branch into multiple branches, e.g., multiple branches
formed through a single optical window or through different optical
windows. Branched tool channels can save cross sectional area when
multiple ports are used.
[0166] The use of a CMOS camera in each of the optical windows 858,
870 can make the neuroendoscope 850 lighter and less bulky than a
neuroendoscope employing a CCD camera or a rod lens. For instance,
the neuroendoscope of FIGS. 22A and 22B can have a weight of less
than about 100 g, such as 40 g, 45 g, 50 g, 60 g, 70 g, 80 g, 90 g,
100 g, or another weight. Furthermore, a CMOS camera included in
each of the optical windows 858, 870 causes the weight of the
neuroendoscope 850 to be substantially evenly distributed along the
length of the neuroendoscope, thus making the neuroendoscope easy
to manipulate and stabilize during surgery.
[0167] In some examples, the multi-port neuroendoscope described
here can have advantages. For instance, the optical windows enable
a user to visualize where the tool is before the tool exits the
neuroendoscope and as the tool exits the neuroendoscope, thus
enhancing safety. The optical windows can also enable a user to
visualize a surgical site even during bleeding. Blood is opaque,
but, as described above, the optical windows allow an optically
clear path to be created between the optical window and the
surgical site. In neurosurgery, light pressure and/or cauterization
can be used to stop venous bleeding. With the optical windows, a
user can visually explore for the source of bleeding, and can
optically see the site in order to apply pressure and/or cauterize
bleeding site.
[0168] In a specific example, intraventricular hemorrhage can be a
fatal complication from endoscopic neurosurgical procedures.
Bleeding inside the ventricle during surgery is often managed by
local warm saline irrigation, by promoting vasospasm and thus
hemostasis. The distal optical window of the multi-port
neuroendoscope described here can exert even soft contact at the
bleeding site, akin to application of gelfoam and cottonoid over
bleeding veins and dural venous sinuses. Since the majority of
intraventricular hemostasis during neurosurgical operations is
performed without tissue contact, warm saline irrigation is the
primary method of controlling minor hemorrhages, while bipolar
coagulation is used for larger bleeding sites. The multi-port
neuroendoscope gives an opportunity to offer focal soft contact
pressure at the bleeding sites, especially venous hemorrhage.
[0169] In some examples, the neuroendoscope can be MR (magnetic
resonance) compatible, enabling the neuroendoscope to be used in
procedures involving endoscopic and MR guidance. "In the treatment
of multi-loculated hydrocephalus, for example, MR imaging can
reveal the extent and direction of intraventricular septations and
periventricular cavitations with respect to the nearest cisterns,
so as to enable fenestration of these optically occluded tissues
resulting in a functioning cysto-ventriculo-cisternostomy. Another
potential application leveraging multiple endoscopic ports and MR
compatibility is transventricular biopsy, resection or laser
ablation of periventricular lesions. This approach could be
particularly beneficial in treating multiple lesions since standard
ventricular access is straightforward and relatively safe compared
with a more time-consuming preoperative planning and traversal of
multiple paths through the brain parenchyma. In addition,
endoscopic imaging could enhance effectiveness by providing optical
imaging of tumor margins and also safety by enabling real-time
visualization of intraprocedural hemorrhage and tool-based
hemostasis."
EXAMPLES
[0170] The invention is further described in the following
examples, which do not limit the scope of the invention described
in the claims.
[0171] The following examples demonstrate the ex vivo and in vivo
use of an instrument including an optical window and a tissue
removal tool for precise removal of endocardial and myocardial
tissue from the interior of a beating porcine heart. Other examples
demonstrate the use of a neuroendoscope including multiple optical
windows.
Example 1
Cardioscope Deployment in Ex Vivo Pulsatile Heart
[0172] Ex vivo removal of endocardial and myocardial tissue from
the interior of the heart was performed using porcine hearts
acquired at a local slaughterhouse. Porcine hearts were submerged
in a water tank and connected to a pulsatile pumping system
allowing both constant pressurization of the left ventricle and a
simulated pumping motion, thus mimicking in vivo conditions in an
ex vivo beating heart environment. Referring to FIG. 9, the
instrument 400 including a tissue removal tool was inserted into
the heart through the free wall 402 of the right ventricle 404 to
remove excess tissue in the infundibulum 406 below the pulmonary
valve 408.
[0173] Referring to FIGS. 23A and 23B, to enable evaluation of the
precision of the tissue removal, a waterproof blue pen was used to
demark a 15 mm diameter circle 806 on the infundibulum 802 of the
heart. An instrument 800 including a tissue removal tool was then
inserted through an incision in the right ventricular free wall 804
of the heart. As shown in FIG. 23B, a purse string suture 808 was
used to seal the opening of the incision around the instrument
800.
[0174] Both endocardial and myocardial tissue were removed.
Endocardial tissue is the thin, elastic layer lining the inside of
the heart. Endocardial tissue tends to tear off in patches that can
jam a tissue removal tool. Myocardial tissue lies below endocardial
tissue and is more easily cut into small pieces. Based on the
results of tissue removal from multiple hearts using the
cardioscope, it was determined that layer-by-layer tissue removal
was the fastest tissue removal technique that also avoided jamming
of the tissue removal tool in the cardioscope.
[0175] To remove endocardial tissue, the cutting depth of the
tissue removal tool was set to 0.3 mm and the tool rotational speed
was set to 1000 rpm. These settings resulted in the generation of
small pieces of endocardium, thus avoiding jamming of the tissue
removal tool. After the endocardial tissue was removed from the
region of interest, the cutting depth was increased to 0.8 mm and
the tool rotational speed was decreased to 600 rpm. These settings
resulted in a rapid rate of myocardial tissue removal.
[0176] FIGS. 23C and 23D show regions 810, 812 of endocardial and
myocardial tissue removal, respectively. The imaging capabilities
provided by the cardioscope enabled the surgeon to limit tissue
removal to within the region marked by the circle 808. The time to
remove the tissue as shown in FIGS. 23C and 23D was 6 minutes, 25
seconds.
Example 2
In Vivo Cardioscope Deployment
[0177] An in vivo experiment was performed on a 65 kg swine. To
mimic the tissue removal performed for subvalvular stenosis, tissue
was removed in two regions of the infundibulum to enlarge the
outflow tract of the pulmonary valve. Referring to FIG. 24, the
swine was placed on cardiopulmonary bypass and a small incision was
made in the right ventricle free wall 902 of the swine heart. An
instrument 900 including a tissue removal tool was inserted through
the incision and the incision was sealed with a purse string
suture.
[0178] FIGS. 25A-25F show in vivo images of the beating heart
acquired by the optical window of the instrument. FIG. 25A depicts
the view in the blood-filled heart prior to contacting the heart
tissue with the optical window of the instrument. As shown in FIG.
25B, when the optical window of the instrument is near, but not yet
in contact with, the wall of the heart, saline dispensed from the
flushing channel flushes blood away from in front of the optical
window, temporarily providing a clear view of the adjacent heart
tissue.
[0179] To remove endocardial tissue, the cutting depth of the
tissue removal tool was set to 0.3 mm and the tool rotational speed
was set to 1000 rpm. FIGS. 25C and 25D are images obtained by the
optical window of the instrument during endocardium removal. The
wide field of view provided by the optical window assists in
determining the region of contact and provides detailed visual
feedback on cutting progress. In FIGS. 25C and 25D, imaging shows
that endocardial tissue 10 remains in the upper left of the field
of view of the optical window but has been removed from a lower
right region 12.
[0180] After the endocardial tissue was removed from the region of
interest, the cutting depth was increased to 0.8 mm and the tool
rotational speed was decreased to 600 rpm for removal of myocardial
tissue. FIGS. 25E and 25F are images obtained by the optical window
during myocardium removal. The image of FIG. 25F reveals that
regions 14 of the myocardium have a tendency to fragment during
removal.
[0181] The total tissue removal time was 3 minutes, 23 seconds and
the procedure was well tolerated by the animal. Following the
procedure, the animal was sacrificed and the heart was examined.
Referring to FIGS. 26A-26C, the heart was cut open for
visualization of the outflow tract of the pulmonary valve. FIG. 26A
shows the pulmonary valve 20, the tricuspid valve 22, and the
interventricular septum 24. Two regions 26, 28 in the outflow tract
where tissue was removed can be seen. FIGS. 26B and 26C show
close-up views of the regions 26, 28, respectively. The two regions
26, 28 of tissue removal measure 16 mm.times.10 mm and 20
mm.times.7 mm, respectively, and vary in depth up to 6 mm.
[0182] Irrigation and aspiration of the tissue removal tool were
monitored during the tissue removal procedure. The total irrigation
volume of heparinized saline was 210 mL and the volume of aspirated
liquid was 130 mL. Hematocrit tests comparing a blood sample with
the aspirated liquid indicated that only 8 mL of the aspirated
liquid was blood, with the remainder being irrigation fluid. These
results suggest that the optical window is effective in preventing
the aspiration of blood by the tissue removal tool.
[0183] To evaluate entrapment of tissue debris, the aspirated
liquid was filtered using a 40 micron cell strainer (BD Falcon.TM.,
Franklin Lakes, N.J.). The debris was examined under a microscope
and weighed. The largest pieces of tissue debris were less than 3
mm long. The total debris weighed less than 39 mg, indicating that
a significant amount of debris escaped into the bloodstream. The
loss of debris into the bloodstream can be remedied by inserting an
embolic filter in the pulmonary artery during the tissue removal
procedure.
[0184] Referring to FIG. 27, in another in vivo example, a
replacement aortic valve 650 was surgically installed in the heart
of a pig. Four fiducial markers 652 were positioned on the bottom
part of the valve for intraoperative guidance. Two metal rings 654
were integrated into the valve 650 to create paravalvular
leakleakleaks when implanted. While the pig heart was beating, a
cardioscope mounted on the distal tip of a concentric tube robotic
catheter was inserted into the left ventricle from the apex of the
heart. Images of the valve 650 were taken from the ventricle using
the cardioscope. In particular, the cardioscope was used to acquire
images of two of the fiducial markers 652, one of the rings 654,
and a bioprosthetic leaflet 656 made of pig pericardium.
Example 3
Multi-Port Neuroendoscope Testing
[0185] The imaging capability of a multi-port neuroendoscope having
a distal optical window and a lateral optical window designed for
tissue resection at the distal end and electrocautery through the
side port was tested and compared to the imaging capability of
clinically used rigid and flexible neuroendoscopes. Referring to
FIGS. 28A-28D, the neuroendoscope 450 included a straight 150 mm
long plastic tube with a 7 mm outer diameter and an ergonomic
handle on the proximal end thereof. The distal end of the
neuroendoscope 450 included a distal optical window 456 having
three, 1 mm diameter channels 458, 460, 462 positioned close to the
corners of the field of view of a camera 464 housed in the optical
window 456. Illumination was provided by a distal LED 466. These
three channels 458, 460, 462 were used for tools, irrigation, and
aspiration, respectively. A lateral optical window included a
single 1 mm channel 468 with a 7 mm radius of curvature, sized to
deliver a Bugbee wire to perform monopolar cautery for fenestration
of the septum pellucidum. The lateral optical window 468 housed a
side camera 470 and a side LED 472. All channels were lined by
clear polyimide tubes having 1.2 mm outer diameter. Both the distal
camera 464 and the side camera 470 were a 1 mm.times.1 mm.times.1
mm CMOS video camera (250.times.250 pixels, NanEye, Awaiba, Inc.),
and both the distal LED and the side LED were a 1.6 mm.times.1.6 mm
device (Cree Inc., Durham, N.C.).
[0186] Imaging of test targets was performed at multiple
clinically-relevant standoff distances (contact, 5 mm, 10 mm, 15
mm, and 20 mm) through both the distal optical window and the
lateral optical window. Imaging was also performed using clinically
used straight rod-lens and flexible neuroendoscopes. The "USAF
3-bar Resolving Power Test target" (1951) was used as a standard
reference in imaging testing. The target was printed on white paper
using a 1200 dpi printer.
[0187] Referring to FIG. 29, images were obtained using the
multi-port neuroendoscope having distal and lateral optical windows
(sometimes referred to as the multi-port neuroendoscope) and
clinically used rigid and flexible neuroendoscopes at various
stand-off distances between the neuroendoscope and the imaging
target. Since fiber-based neuroendoscopes are often used slightly
defocused to avoid visualization of the boundaries of individual
fibers, FIG. 30 provides both types of images for comparison. Rows
(a) and (b) include crisp and blurred images obtained by a flexible
neuroendoscope, respectively. Rows (c) and (d) include images
obtained through the distal optical window and the lateral optical
window, respectively, of the multi-port neuroendoscope. Row (3)
includes images obtained by a rigid lens straight clinical
endoscope. In contact with the imaging target, only the multi-port
neuroendoscope provided a clear, focused view of the imaging
target. For all non-contact distances, the image quality of the
multiport endoscope was between that of the rigid scope and the
flexible scope.
[0188] The MRI (magnetic resonance imaging) compatibility of
multi-port neuroendoscope was evaluated by testing the
neuroendoscope inside a scanner. MR compatibility testing included
three components: testing for dangerous magnetic forces or torques
as the neuroendoscope was introduced into and manipulated inside
the bore of the MR scanner; determining the size of any MR
artifacts produced by the neuroendoscope in surrounding tissue; and
ensuring normal operation of the cameras in the neuroendoscope
inside the MR scanner. These tests demonstrated the capability to
both obtain MR images of tissue adjacent to the multi-port
neuroendoscope and to stream video images from the neuroendoscope
from within the MR scanner.
[0189] For MR compatibility testing, a multi-port neuroendoscope
was inserted manually into the bore of an MR scanner (Skyra 3T,
Siemens) and moved throughout the interior of the bore. Cephalic
MRI was performed in a freshly sacrificed adult female Yorkshire
pig (sus scrofa domesticus). After evaluating the brain anatomy,
the endoscope was advanced trans-cranially through a pre-positioned
burr hole into a lateral ventricle inside the scanner bore. MR
images were acquired using standard neurosurgical imaging sequences
including of T2 weighted FLAIR. Separately, endoscope video
sequences were acquired with and without simultaneous MR pulse
sequence execution using the test targets to more easily detect any
changes in image quality during scanning.
[0190] When the multi-port neuroendoscope was inserted into the
bore of the MR scanner and moved manually, no magnetic forces were
perceived, and video stream from the neuroendoscope was unaffected
by placement inside the bore. When pulse sequences were executed
during video streaming, the radio frequency (RF) portion of the
pulse sometimes interfered with video streaming. It is believed
that this interference may have been because the cameras of the
neuroendoscope were not RF shielded. Images of the neuroendoscope
inside a porcine brain were recorded and are shown in FIG. 30. The
neuroendoscope appears as a void in these images. While artifacts
of instruments in MR images are often larger than the instruments
themselves, the size of the neuroendoscope artifact corresponds to
the actual size of the neuroendoscope.
[0191] To evaluate the capability of the multi-port neuroendoscope
in the context of a multi-port procedure, a combined colloid cyst
resection and septostomy were performed in a cadaver head. After
creating a frontal burr hole on a human cadaver skull and a
cruciate durotomy, an obturator was introduced into the parenchyma
to evaluate imaging in the presence of blood. The cavity was filled
with blood and a multi-port neuroendoscope was introduced. To
determine if the distal and lateral optical windows of the
neuroendoscope would enable visualization of tissue during contact
with tissue, the neuroendoscope was slowly advanced until contact
was made between the distal optical window and the tissue.
[0192] Considering the fixed shrunken cadaveric ventricular
anatomy, a 4-burr-hole craniotomy was made to implant an artificial
colloid cyst trans-callosally at the left foramen of Monro. To make
the colloid cyst phantom, 0.05% ultra-pure agarose (Life
Technologies, CA) was dissolved in 1.times. PBS by boiling in micro
oven and cooled down to 45.degree. C., before adding cheese cream
for whitish color. Immediately, the whole mixture was poured into a
stretched Parafilm (Neenah, Wis., USA), to simulate a colloid cyst
with whitish viscous contents that can be readily aspirated.
Septostomy was performed inside the cadaver head using a Bugbee
wire inserted through a tool channel of the lateral optical window
of the multi-port neuroendoscope under direct vision. The scattered
cadaver debris in the ventricles obscured the views for both a
standard endoscope and the multi-port neuroendoscope. Consequently,
a phantom test bed was made in a clear saline-filled container to
perform cutting, suction and irrigation on the colloid cyst
phantom.
[0193] The ability of the multi-port neuroendoscope to visualize
tissue while in contact with tissue is illustrated in FIGS. 31A and
31B. As with a standard scope, nothing can be seen in a
blood-filled cavity (FIG. 31A). Once soft contact is made with the
tissue, however, the silicone optical window displaces the blood in
front of the camera, making clear visualization possible (FIG.
31B).
[0194] Fenestration and aspiration of a colloid cyst using a
multi-port neuroendoscope was demonstrated in a phantom test bed.
Endoscopic tip views of the classic skill sets of cutting, suction
and irrigation on the colloid cyst phantom are shown in FIGS.
32A-32F, captured by the camera housed in the distal optical window
of the multip-port neuroendoscope. In particular, FIG. 32A is an
image of two channels formed in the distal silicone optical window.
FIGS. 32B and 32C are images of endoscopic graspers used to hold
the capsule. FIGS. 32D and 32E are images of suction and
irrigation, and FIG. 32F is an image following emptying of the cyst
contents off the capsule.
[0195] Referring to FIGS. 33A-33E, the lateral port of the
multi-port neuroendoscope was used to perform septostomy inside the
cadaver head while maintaining a stable view of the anterior field
near the colloid cyst phantom at the foramen of Monro. FIG. 33A
shows a close-up view through the distal optical window of the
membranous capsule of the colloid cyst phantom. FIGS. 33B-33E are
images of the sequential septostomy steps of advancing the lateral
port of the neuroendoscope toward the septum, passing the Bugbee
wire through a channel of the lateral optical window (FIG. 33C),
and firing the coagulation probe to coagulate the septum (FIG.
33D). FIG. 33E is an image of the septostomy hole.
OTHER EMBODIMENTS
[0196] It is to be understood that while the invention has been
described in conjunction with the detailed description thereof, the
foregoing description is intended to illustrate and not limit the
scope of the invention, which is defined by the scope of the
appended claims. Other aspects, advantages, and modifications are
within the scope of the following claims.
* * * * *