U.S. patent application number 13/836017 was filed with the patent office on 2013-10-17 for wheel for robotic catheter system drive mechanism.
The applicant listed for this patent is Corindus, Inc.. Invention is credited to John Murphy, Tal Wenderow, Christopher Zirps.
Application Number | 20130274657 13/836017 |
Document ID | / |
Family ID | 45831952 |
Filed Date | 2013-10-17 |
United States Patent
Application |
20130274657 |
Kind Code |
A1 |
Zirps; Christopher ; et
al. |
October 17, 2013 |
WHEEL FOR ROBOTIC CATHETER SYSTEM DRIVE MECHANISM
Abstract
A drive mechanism for a robotic catheter system including a
first engagement surface and a second engagement surface is
provided. The first engagement surface and second engagement
surface are configured to engage a catheter device to allow the
drive mechanism to impart motion to the catheter device. The first
engagement surface is textured to facilitate gripping between the
first engagement surface and the catheter device.
Inventors: |
Zirps; Christopher; (Sharon,
MA) ; Wenderow; Tal; (Newton, MA) ; Murphy;
John; (North Reading, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Corindus, Inc. |
Waltham |
MA |
US |
|
|
Family ID: |
45831952 |
Appl. No.: |
13/836017 |
Filed: |
March 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/US11/51542 |
Sep 14, 2011 |
|
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|
13836017 |
|
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|
61384174 |
Sep 17, 2010 |
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Current U.S.
Class: |
604/95.01 |
Current CPC
Class: |
A61M 25/0147 20130101;
A61M 25/0116 20130101; A61M 25/0113 20130101; A61M 25/09041
20130101; A61B 2090/3764 20160201; A61B 34/30 20160201; A61B
2034/301 20160201 |
Class at
Publication: |
604/95.01 |
International
Class: |
A61M 25/01 20060101
A61M025/01 |
Claims
1. A drive mechanism for a robotic catheter system which imparts
both axial and rotational motion comprising: a tire of a drive
wheel and a tire of an idler wheel which interact with each other,
each of which has an engagement surface which interacts with a
catheter device to cause it to move along its axis and which is
free of any gripping features which run perpendicular to the axis
of the catheter device; and a set of rotational drive assembly
wheel tires each of which has an engagement surface which interacts
with a catheter device to cause it to rotate about its axis and
which has a gripping feature which runs perpendicular to the axis
of the catheter device.
2. The drive mechanism of claim 1 wherein the engagement surfaces
of both of the rotational drive assembly wheel tires has a
durometer hardness of no more than about 85 A.
3. The drive mechanism of claim 1 wherein the engagement surface of
at least one of the rotational drive assembly wheel tires has slits
which run perpendicular to the axis of the catheter device.
4. The drive mechanism of claim 3 wherein the engagement surface of
both of the rotational drive assembly wheel tires of the set has
slits which run perpendicular to the axis of the catheter
device.
5. The drive mechanism of claim 3 wherein the rotational drive
assembly wheel tires of the set apply a substantially lighter pinch
force to the catheter device than do the drive wheel tire and idler
wheel tire.
6. The drive mechanism of claim 5 wherein the drive wheel tire and
the idler wheel tire apply a pinch force of about 9 pounds to the
catheter device and the rotational drive assembly wheel tires apply
a pinch force of about 1.25 pounds to the catheter device.
7. The drive mechanism of claim 3 wherein there are three sets of
rotational drive assembly wheel tires.
8. The drive mechanism of claim 1 wherein the engagement surfaces
of both the drive wheel tire and the idler wheel tire have a
durometer hardness of at least about 95 A.
9. The drive mechanism of claim 1 which includes an auxiliary
encoder wheel tire with an engagement surface which interacts with
the catheter device which has a durometer hardness of no more than
about 85 A.
10. The drive mechanism of claim 9 wherein the auxiliary encoder
wheel tire and an encoder idler wheel tire which interacts with the
auxiliary encoder wheel tire apply a substantially lighter pinch
force to the catheter device than do the drive wheel tire and idler
wheel tire.
11. The drive mechanism of claim 10 wherein the drive wheel tire
and the idler wheel tire apply a pinch force of about 9 pounds to
the catheter device and the auxiliary encoder wheel tire and an
encoder idler wheel tire apply a pinch force of about 0.75 pounds
to the catheter device.
12. The drive mechanism of claim 1 wherein the radial thickness of
both the drive wheel tire and the idler wheel tire is between about
0.03 and 0.06 inches.
13. The drive mechanism of claim 10 wherein the engagement surface
of each the drive wheel tire and the idler wheel tire has a
durometer hardness of less than about 50 D.
14. The drive mechanism of claim 1 wherein catheter device is a
guide catheter or a working catheter which deploys an angioplasty
balloon or a stent.
15. The drive mechanism of claim 1 wherein the catheter device is a
guide wire.
16. The drive mechanism of claim 15 wherein the guide wire has a
diameter between about 0.014 inches and 0.038 inches.
17. The drive mechanism of claim 1 wherein the guide wire has a
diameter of about 0.014 inches.
18. A drive mechanism for a robotic catheter system which imparts
both axial and rotational motion comprising: a drive wheel tire and
an idler wheel tire which interact with each other, each of which
has an engagement surface which interacts with a catheter device to
cause it to move along its axis; and a set of rotational drive
assembly wheel tires each of which has an engagement surface which
interacts with a catheter device to cause it to rotate about its
axis; wherein one or more of the tires has a composite structure in
which a material or structure of higher resilience is interposed
between its engagement surface and the hub on which it is
mounted.
19. The drive mechanism of claim 18 wherein the rotational drive
assembly wheel tires have the composite structure.
20. The drive mechanism of claim 19 wherein interposed material or
structure of higher resilience is a pressurized fluid, a high
resistance o-ring or a canted coil spring.
21. The drive mechanism of claim 18 wherein the engagement surface
of at least one of the rotational drive assembly wheel tires has
slits which run perpendicular to the axis of the catheter
device.
22. The drive mechanism of claim 18 wherein the catheter device is
a guide wire.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part to Application
No. PCT/US11/51542, filed Sep. 14, 2011, which claims the benefit
of U.S. Provisional Application No. 61/384,174, filed Sep. 17,
2010, both of which are incorporated herein by reference in their
entireties.
BACKGROUND
[0002] The present invention relates generally to the field of
catheter systems for performing diagnostic and/or intervention
procedures. The present invention relates specifically to catheter
systems and methods including a roller wheel based drive
mechanism.
[0003] Vascular disease, and in particular cardiovascular disease,
may be treated in a variety of ways. Surgery, such as cardiac
bypass surgery, is one method for treating cardiovascular disease.
However, under certain circumstances, vascular disease may be
treated with a catheter based intervention procedure, such as
angioplasty. Catheter based intervention procedures are generally
considered less invasive than surgery. If a patient shows symptoms
indicative of cardiovascular disease, an image of the patient's
heart may be taken to aid in the diagnosis of the patient's disease
and to determine an appropriate course of treatment. For certain
disease types, such as atherosclerosis, the image of the patient's
heart may show a lesion that is blocking one or more coronary
arteries. Following the diagnostic procedure, the patient may
undergo a catheter based intervention procedure. During one type of
intervention procedure, a catheter is inserted into the patient's
femoral artery and moved through the patient's arterial system
until the catheter reaches the site of the lesion. In some
procedures, the catheter is equipped with a balloon or a stent that
when deployed at the site of a lesion allows for increased blood
flow through the portion of the coronary artery that is affected by
the lesion. In addition to cardiovascular disease, other diseases
(e.g., hypertension, etc.) may be treated using catheterization
procedures.
SUMMARY
[0004] One embodiment of the invention relates to a drive mechanism
for a robotic catheter system which imparts both axial and
rotational motion. The mechanism includes a tire of a drive wheel
and a tire of an idler wheel which interact with each other, each
of which has an engagement surface which interacts with a catheter
device to cause it to move along its axis and which is free of any
gripping features which run perpendicular to the axis of the
catheter device. It also includes a set of rotational drive
assembly wheel tires each of which has an engagement surface which
interacts with a catheter device to cause it to rotate about its
axis and which has a gripping feature which runs perpendicular to
the axis of the catheter device.
[0005] Another embodiment of the invention relates to a drive
mechanism for a robotic catheter system which imparts both axial
and rotational motion using a composite tire on one or more of the
wheels of the drive mechanism. The mechanism includes a drive wheel
tire and an idler wheel tire which interact with each other, each
of which has an engagement surface which interacts with a catheter
device to cause it to move along its axis and a set of rotational
drive assembly wheel tires each of which has an engagement surface
which interacts with a catheter device to cause it to rotate about
its axis. One or more of the tires has a composite structure in
which a material or structure of higher resilience is interposed
between its engagement surface and the hub on which it is
mounted.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] This application will become more fully understood from the
following detailed description, taken in conjunction with the
accompanying figures, wherein like reference numerals refer to like
elements in which:
[0007] FIG. 1 is a perspective view of a catheter procedure system
according to an exemplary embodiment;
[0008] FIG. 2 is a block diagram of a catheter procedure system
according to an exemplary embodiment;
[0009] FIG. 3 is a perspective view of a bedside system showing an
embodiment of a cassette prior to being attached to a motor drive
base;
[0010] FIG. 4 is a perspective view of a bedside system showing the
cassette of FIG. 3 following attachment to the motor drive
base;
[0011] FIG. 5 is a perspective view of a cassette in the "loading"
configuration;
[0012] FIG. 6 is a perspective view of a cassette in the "loaded"
or "use" configuration;
[0013] FIG. 7 is an exploded perspective view of an axial drive
assembly of a cassette;
[0014] FIG. 8 is a bottom perspective view of a cassette showing
the base plate removed;
[0015] FIG. 9 is a top view showing the axial drive assembly in the
"disengaged" position;
[0016] FIG. 10 is a top view showing the axial drive assembly in
the "engaged" position;
[0017] FIG. 11 is a top perspective view of a rotational drive
assembly of a cassette showing the engagement structure in broken
lines beneath the chassis;
[0018] FIG. 12 is a top perspective view of a rotational drive
assembly with the chassis shown in broken lines;
[0019] FIG. 13 is a top view of the rotational drive assembly in
the "engaged" position;
[0020] FIG. 14 is a top view of the rotational drive assembly in
the "disengaged" position;
[0021] FIG. 15 is a sectional view of the rotational drive assembly
taken generally along line 15-15 in FIG. 6;
[0022] FIG. 16 is a sectional view of the axial drive assembly
taken generally along line 16-16 in FIG. 6;
[0023] FIG. 17A shows a rotational drive assembly coupled to a base
plate of a cassette;
[0024] FIG. 17B shows depression of a release button to disconnect
the rotational drive assembly from the base plate of the
cassette;
[0025] FIG. 17C shows removal of the rotational drive assembly from
the base plate of the cassette leaving the guide wire in place;
[0026] FIG. 18 shows a side view of a roller wheel according to an
exemplary embodiment;
[0027] FIG. 19A shows a top view of the roller wheel of FIG.
18;
[0028] FIG. 19B shows an enlarged view of a portion of the roller
wheel of FIG. 19B;
[0029] FIG. 20 is an exploded view showing a wheel separator
structure according to an exemplary embodiment;
[0030] FIG. 21 is a rear perspective view of the structure of FIG.
20;
[0031] FIG. 22 is a front perspective view of the structure of FIG.
20 engaged with a rotational drive assembly according to an
exemplary embodiment; and
[0032] FIG. 23 is a perspective view from below of the structure of
FIG. 20 engaged with a rotational drive assembly according to an
exemplary embodiment.
DETAILED DESCRIPTION
[0033] Before turning to the figures, which illustrate the
exemplary embodiments in detail, it should be understood that the
present application is not limited to the details or methodology
set forth in the description or illustrated in the figures. It
should also be understood that the terminology is for the purpose
of description only and should not be regarded as limiting.
[0034] Referring to FIG. 1, a catheter procedure system 10 is
shown. Catheter procedure system 10 may be used to perform catheter
based medical procedures (e.g., percutaneous intervention
procedures). Percutaneous intervention procedures may include
diagnostic catheterization procedures during which one or more
catheters are used to aid in the diagnosis of a patient's disease.
For example, during one embodiment of a catheter based diagnostic
procedure, a contrast media is injected into one or more coronary
arteries through a catheter and an image of the patient's heart is
taken. Percutaneous intervention procedures may also include
catheter based therapeutic procedures (e.g., balloon angioplasty,
stent placement, treatment of peripheral vascular disease, etc.)
during which a catheter is used to treat a disease. It should be
noted, however, that one skilled in the art would recognize that
certain specific percutaneous intervention devices or components
(e.g., type of guide wire, type of catheter, etc.) will be selected
based on the type of procedure that is to be preformed. Catheter
procedure system 10 is capable of performing any number of catheter
based medical procedures with minor adjustments to accommodate the
specific percutaneous devices to be used in the procedure. In
particular, while the embodiments of catheter procedure system 10
described herein are explained primarily in relation to the
diagnosis and/or treatment of coronary disease, catheter procedure
system 10 may be used to diagnose and/or treat any type of disease
or condition amenable to diagnosis and/or treatment via a catheter
based procedure.
[0035] Catheter procedure system 10 includes lab unit 11 and
workstation 14. Catheter procedure system 10 includes a robotic
catheter system, such as bedside system 12, located within lab unit
11 adjacent patient 21. Generally, bedside system 12 may be
equipped with the appropriate percutaneous devices (e.g., guide
wires, guide catheters, working catheters, catheter balloons,
stents, diagnostic catheters, etc.) or other components (e.g.,
contrast media, medicine, etc.) to allow the user to perform a
catheter based medical procedure. A robotic catheter system, such
as bedside system 12, may be any system configured to allow a user
to perform a catheter based medical procedure via a robotic system
by operating various controls such as the controls located at
workstation 14. Bedside system 12 may include any number and/or
combination of components to provide bedside system 12 with the
functionality described herein. Bedside system 12 may include a
cassette 56 coupled to a base 19, and cassette 56 may include a
housing 22 that supports the various components of the cassette.
One particular embodiment of a cassette (shown as cassette 300) is
described below in relation to FIGS. 3-23.
[0036] In one embodiment, bedside system 12 may be equipped to
perform a catheter based diagnostic procedure. In this embodiment,
bedside system 12 may be equipped with one or more of a variety of
catheters for the delivery of contrast media to the coronary
arteries. In one embodiment, bedside system 12 may be equipped with
a first catheter shaped to deliver contrast media to the coronary
arteries on the left side of the heart, a second catheter shaped to
deliver contrast media to the coronary arteries on the right side
of the heart, and a third catheter shaped to deliver contrast media
into the chambers of the heart.
[0037] In another embodiment, bedside system 12 may be equipped to
perform a catheter based therapeutic procedure. In this embodiment,
bedside system 12 may be equipped with a guide catheter, a guide
wire, and a working catheter (e.g., a balloon catheter, a stent
delivery catheter, ablation catheter, etc.). In one embodiment, the
working catheter may be an over-the-wire working catheter that
includes a central lumen that is threaded over the guide wire
during a procedure. In another embodiment, the working catheter
includes a secondary lumen that is separate from the central lumen
of the working catheter, and the secondary lumen is threaded over
the guide wire during a procedure. In another embodiment, bedside
system 12 may be equipped with an intravascular ultrasound (IVUS)
catheter. In another embodiment, any of the percutaneous devices of
bedside system 12 may be equipped with positional sensors that
indicate the position of the component within the body.
[0038] Bedside system 12 is in communication with workstation 14,
allowing signals generated by the user inputs and control system of
workstation 14 to be transmitted to bedside system 12 to control
the various functions of beside system 12. Bedside system 12 also
may provide feedback signals (e.g., operating conditions, warning
signals, error codes, etc.) to workstation 14. Bedside system 12
may be connected to workstation 14 via a communication link 38 that
may be a wireless connection, cable connectors, or any other means
capable of allowing communication to occur between workstation 14
and beside system 12.
[0039] Workstation 14 includes a user interface 30 configured to
receive user inputs to operate various components or systems of
catheter procedure system 10. User interface 30 includes controls
16. Controls 16 allow the user to control bedside system 12 to
perform a catheter based medical procedure. For example, controls
16 may be configured to cause bedside system 12 to perform various
tasks using the various percutaneous devices with which bedside
system 12 may be equipped (e.g., to advance, retract, or rotate a
guide wire, advance, retract, or rotate a working catheter,
advance, retract, or rotate a guide catheter, inflate or deflate a
balloon located on a catheter, position and/or deploy a stent,
inject contrast media into a catheter, inject medicine into a
catheter, or to perform any other function that may be performed as
part of a catheter based medical procedure, etc.). In some
embodiments, one or more of the percutaneous intervention devices
may be steerable, and controls 16 may be configured to allow a user
to steer one or more steerable percutaneous device. In one such
embodiment, bedside system 12 may be equipped with a steerable
guide catheter, and controls 16 may also be configured to allow the
user located at remote workstation 14 to control the bending of the
distal tip of a steerable guide catheter.
[0040] In one embodiment, controls 16 include a touch screen 18, a
dedicated guide catheter control 29, a dedicated guide wire control
23, and a dedicated working catheter control 25. In this
embodiment, guide wire control 23 is a joystick configured to
advance, retract, or rotate a guide wire, working catheter control
25 is a joystick configured to advance, retract, or rotate a
working catheter, and guide catheter control 29 is a joystick
configured to advance, retract, or rotate a guide catheter. In
addition, touch screen 18 may display one or more icons (such as
icons 162, 164, and 166) that control movement of one or more
percutaneous devices via bedside system 12. Controls 16 may also
include a balloon or stent control that is configured to inflate or
deflate a balloon and/or a stent. Each of the controls may include
one or more buttons, joysticks, touch screens, etc., that may be
desirable to control the particular component to which the control
is dedicated.
[0041] Controls 16 may include an emergency stop button 31 and a
multiplier button 33. When emergency stop button 31 is pushed a
relay is triggered to cut the power supply to bedside system 12.
Multiplier button 33 acts to increase or decrease the speed at
which the associated component is moved in response to a
manipulation of guide catheter control 29, guide wire control 23,
and working catheter control 25. For example, if operation of guide
wire control 23 advances the guide wire at a rate of 1 mm/sec,
pushing multiplier button 33 may cause the operation of guide wire
control 23 to advance the guide wire at a rate of 2 mm/sec.
Multiplier button 33 may be a toggle allowing the multiplier effect
to be toggled on and off. In another embodiment, multiplier button
33 must be held down by the user to increase the speed of a
component during operation of controls 16.
[0042] User interface 30 may include a first monitor 26 and a
second monitor 28. First monitor 26 and second monitor 28 may be
configured to display information or patient-specific data to the
user located at workstation 14. For example, first monitor 26 and
second monitor 28 may be configured to display image data (e.g.,
x-ray images, MRI images, CT images, ultrasound images, etc.),
hemodynamic data (e.g., blood pressure, heart rate, etc.), patient
record information (e.g., medical history, age, weight, etc.). In
one embodiment, monitors 26 and/or 28 may be configured to display
an image of a portion of the patient (e.g., the patient's heart) at
one or more magnification levels. In addition, first monitor 26 and
second monitor 28 may be configured to display procedure specific
information (e.g., duration of procedure, catheter or guide wire
position, volume of medicine or contrast agent delivered, etc.).
Monitor 26 and monitor 28 may be configured to display information
regarding the position and/or bend of the distal tip of a steerable
guide catheter. Further, monitor 26 and monitor 28 may be
configured to display information to provide the functionalities
associated with the various modules of controller 40 discussed
below. In another embodiment, user interface 30 includes a single
screen of sufficient size to display one or more of the display
components and/or touch screen components discussed herein.
[0043] Catheter procedure system 10 also includes an imaging system
32 located within lab unit 11. Imaging system 32 may be any medical
imaging system that may be used in conjunction with a catheter
based medical procedure (e.g., non-digital x-ray, digital x-ray,
CT, MRI, ultrasound, etc.). In an exemplary embodiment, imaging
system 32 is a digital x-ray imaging device that is in
communication with workstation 14. Referring to FIG. 1, imaging
system 32 may include a C-arm that allows imaging system 32 to
partially or completely rotate around patient 21 in order to obtain
images at different angular positions relative to patient 21 (e.g.,
sagital views, caudal views, cranio-caudal views, etc.).
[0044] Imaging system 32 is configured to take x-ray images of the
appropriate area of patient 21 during a particular procedure. For
example, imaging system 32 may be configured to take one or more
x-ray images of the heart to diagnose a heart condition. Imaging
system 32 may also be configured to take one or more x-ray images
during a catheter based medical procedure (e.g., real-time images)
to assist the user of workstation 14 to properly position a guide
wire, guide catheter, working catheter, stent, etc. during the
procedure. The image or images may be displayed on first monitor 26
and/or second monitor 28.
[0045] In addition, the user of workstation 14 may be able to
control the angular position of imaging system 32 relative to the
patient to obtain and display various views of the patient's heart
on first monitor 26 and/or second monitor 28. Displaying different
views at different portions of the procedure may aid the user of
workstation 14 to properly move and position the percutaneous
devices within the 3D geometry of the patient's heart. In an
exemplary embodiment, imaging system 32 may be any 3D imaging
modality of the past, present, or future, such as an x-ray based
computed tomography (CT) imaging device, a magnetic resonance
imaging device, a 3D ultrasound imaging device, etc. In this
embodiment, the image of the patient's heart that is displayed
during a procedure may be a 3D image. In addition, controls 16 may
also be configured to allow the user positioned at workstation 14
to control various functions of imaging system 32 (e.g., image
capture, magnification, collimation, c-arm positioning, etc.).
[0046] Referring to FIG. 2, a block diagram of catheter procedure
system 10 is shown according to an exemplary embodiment. Catheter
procedure system 10 may include a control system, such as
controller 40. Controller 40 may be part of workstation 14.
Controller 40 may generally be an electronic control unit suitable
to provide catheter procedure system 10 with the various
functionalities described herein. For example, controller 40 may be
an embedded system, a dedicated circuit, a general purpose system
programmed with the functionality described herein, etc. Controller
40 is in communication with one or more bedside systems 12,
controls 16, monitors 26 and 28, imaging system 32, and patient
sensors 35 (e.g., electrocardiogram ("ECG") devices,
electroencephalogram ("EEG") devices, blood pressure monitors,
temperature monitors, heart rate monitors, respiratory monitors,
etc.). In various embodiments, controller 40 is configured to
generate control signals based on the user's interaction with
controls 16 and/or based upon information accessible to controller
40 such that a medical procedure may be preformed using catheter
procedure system 10. In addition, controller 40 may be in
communication with a hospital data management system or hospital
network 34, and one or more additional output devices 36 (e.g.,
printer, disk drive, cd/dvd writer, etc.).
[0047] Communication between the various components of catheter
procedure system 10 may be accomplished via communication links 38.
Communication links 38 may be dedicated wires or wireless
connections. Communication links 38 may also represent
communication over a network. Catheter procedure system 10 may be
connected or configured to include any other systems and/or devices
not explicitly shown. For example, catheter procedure system 10 may
include IVUS systems, image processing engines, data storage and
archive systems, automatic balloon and/or stent inflation systems,
medicine tracking and/or logging systems, user logs, encryption
systems, systems to restrict access or use of catheter procedure
system 10, robotic catheter systems of the past, present, or
future, etc.
[0048] Referring now to FIGS. 3 through 17C, an exemplary
embodiment of a cassette for use with a robotic catheter system is
shown. Cassette 300 may be equipped with a guide wire 301 and a
working catheter 303 to allow a user to perform a catheterization
procedure utilizing cassette 300. In this embodiment, bedside
system 12 includes a cassette 300 configured to be mounted to a
motor drive base 302. FIG. 3 shows a bottom perspective view of
cassette 300 prior to mounting to motor drive base 302. Motor drive
base 302 includes a first capstan 304, a second capstan 306, and a
third capstan 308, and cassette 300 includes a first capstan socket
310, a second capstan socket 312, and a third capstan socket 314.
Cassette 300 includes a housing 316, and housing 316 includes a
base plate 318.
[0049] Each of the capstan sockets is configured to receive one of
the capstans of motor drive base 302. In the embodiment shown, base
plate 318 includes a hole or aperture aligned with each of the
capstan sockets 310, 312, and 314 to allow each capstan to engage
with the appropriate capstan socket. The engagement between the
capstans and capstan sockets allows the transfer of energy (e.g.,
rotational movement) generated by one or more actuators (e.g.,
motors) located within motor drive base 302 to each of the drive
mechanisms (discussed below) within cassette 300. In one
embodiment, a single actuator provides energy to each of the drive
mechanisms. In another embodiment, there is an actuator that drives
capstan 304, an actuator that drives capstan 306, and an actuator
that drives capstan 308. Further, the positioning of the capstans
and capstan sockets helps the user to align cassette 300 relative
to motor drive base 302 by allowing cassette 300 to be mounted to
motor drive base 302 only when all three capstan sockets are
aligned with the proper capstan.
[0050] In one embodiment, the motors that drive capstans 304, 306,
and 308 are located within motor drive base 302. In another
embodiment, the motors that drive capstans 304, 306, and 308 may be
located outside of base 302 connected to cassette 300 via an
appropriate transmission device (e.g., shaft, cable, etc.). In yet
another embodiment, cassette 300 includes motors located within the
housing of cassette 300. In another embodiment, cassette 300 does
not include capstan sockets 310, 312, and 314, but includes an
alternative mechanism for transferring energy (e.g., rotational
motion) from an actuator external to the cassette to each of the
cassette drive mechanisms. For example, rotational movement may be
transferred to the drive mechanisms of cassette 300 via alternating
or rotating magnets or magnetic fields located within motor drive
base 302.
[0051] In the embodiment shown, cassette 300 also includes a guide
catheter support 311 that supports guide catheter 317 at a position
spaced from cassette 300. As shown, guide catheter support 311 is
attached to cassette 300 by a rod 313. Rod 313 and guide catheter
support 311 are strong enough to support guide catheter 317 without
buckling. Guide catheter support 311 supports guide catheter 317 at
a position spaced from the cassette, between the patient and the
cassette to prevent buckling, bending, etc. of the portion of guide
catheter 317 between the cassette and the patient.
[0052] Referring to FIG. 4, cassette 300 is shown mounted to motor
drive base 302. As shown in FIG. 4, cassette 300 includes an outer
cassette cover 320 that may be attached to housing 316. When
attached to housing 316, outer cassette cover 320 is positioned
over and covers each of the drive mechanisms of cassette 300. By
covering the drive assemblies of cassette 300, outer cassette cover
320 acts to prevent accidental contact with the drive mechanisms of
cassette 300 while in use.
[0053] Referring to FIG. 5, cassette 300 is shown in the "loading"
configuration with outer cassette cover 320 removed. Cassette 300
includes a y-connector support assembly 322, an axial drive
assembly 324, and a rotational drive assembly 326. Generally, the
various portions of cassette 300 are placed in the loading
configuration to allow the user to load or install a guide wire
and/or working catheter into cassette 300. Further, in the
exemplary embodiment shown, y-connector support assembly 322 is
located in front of axial drive assembly 324, and axial drive
assembly 324 is located in front of rotational drive assembly 326
within cassette 300.
[0054] Y-connector support assembly 322 includes a chassis 328 and
a y-connector restraint 330. Base plate 318 includes a support arm
332 that supports y-connector support assembly 322. Chassis 328 is
coupled to the front of support arm 332 via pin connection 334.
[0055] A central groove or depression 336 extends the length of
chassis 328. Y-connector 338 rests within central groove 336 of
chassis 328. Y-connector 338 includes a first leg 340, a second leg
342, and a third leg 344. First leg 340 is configured to attach to
a guide catheter such that the central lumen of the y-connector is
in fluid communication with the central lumen of the guide
catheter. Second leg 342 is angled away from the longitudinal axis
of y-connector 338. Second leg 342 of y-connector 338 allows
introduction of a contrast agent or medicine into the lumen of the
guide catheter. A one way valve prohibits bodily fluid from exiting
second leg 342. Third leg 344 extends away from the guide catheter
toward axial drive assembly 324. In use, guide wire 301 and working
catheter 303 are inserted into third leg 344 of y-connector 338 via
opening 346 and may be advanced through y-connector 338 into the
lumen of the guide catheter. The third leg also includes a one way
valve that permits insertion and removal of the working catheter
and guide wire but prohibits bodily fluids from exiting third leg
344.
[0056] Chassis 328 is rotatable about an axis defined by pin
connection 334 to allow chassis 328 to be placed in the "loading
position" shown in FIG. 5. In the loading position, chassis 328 is
positioned at about a 45 degree angle, shown by angle line 315,
relative to support arm 332. Chassis 328 is moved to the "loading
position" to provide easier access to opening 346 of the third leg
344 allowing the user to feed guide wire 301 and working catheter
303 into y-connector 338.
[0057] Y-connector support assembly 322 includes y-connector
restraint 330. Y-connector restraint 330 is configured to
releasably engage y-connector 338. In the engaged position shown in
FIG. 5, engagement arm 348 of y-connector restraint 330 engages or
presses y-connector 338 into central groove 336 to securely hold
y-connector 338. Y-connector restraint 330 may be moved to a
disengaged position to release y-connector 338 from chassis
328.
[0058] Cassette 300 also includes an axial drive assembly 324.
Axial drive assembly 324 includes a first axial drive mechanism,
shown as guide wire axial drive mechanism 350, and a second axial
drive mechanism, shown as working catheter axial drive mechanism
352. Axial drive assembly 324 also includes a top deck 354, a cover
356, and a latch or handle 358.
[0059] Generally, guide wire axial drive mechanism 350 is
configured to releasably engage and drive (e.g., to impart motion
to) guide wire 301 along its longitudinal axis. In this manner,
guide wire axial drive mechanism 350 provides for advancement
and/or retraction of guide wire 301. Working catheter axial drive
mechanism 352 is configured to releasably engage and drive (e.g.,
to impart motion to) working catheter 303 along its longitudinal
axis. In this manner, working catheter axial drive mechanism 352
provides for advancement and/or retraction of working catheter
303.
[0060] Top deck 354 is mounted to a central portion 360 of base
plate 318. Top deck 354 includes a guide wire channel 364 and a
working catheter channel 366. Guide wire channel 364 is positioned
generally perpendicular to the top surface of top deck 354 and runs
the length of top deck 354 in the longitudinal direction. Working
catheter channel 366 is positioned generally perpendicular to the
top surface of top deck 354 and is located at an angle relative to
guide wire channel 364. A plurality of tabs 368 extend vertically
from the top surface of top deck 354 along guide wire channel
364.
[0061] In FIG. 5, cover 356 is shown in the open position. Handle
358 is moved to a position generally parallel to the longitudinal
axis of cassette 300 to allow cover 356 to move to the open
position. Cover 356 is mounted to top deck 354 via hinges 370.
Cassette 300 includes a restraint structure that acts to restrain
movement of the guide wire when cover 356 is in the closed
position. As shown, the restraint structure includes a plurality of
tabs 372 extending from the lower surface of cover 356. Tabs 372
are positioned such that when cover 356 is closed, tabs 372 are
positioned within a portion of guide wire channel 364 between tabs
368 such that tabs 372 restrain movement of guide wire 301 in a
vertical direction (i.e., restrains movement of the guide wire in a
direction perpendicular to the top surface of top deck 354).
[0062] When cover 356 is in the open position, both guide wire
axial drive mechanism 350 and working catheter axial drive
mechanism 352 are exposed allowing the user to load cassette 300
with a guide wire and working catheter. With cover 356 open, guide
wire 301 is loaded into axial drive assembly 324 by placing the
guide wire into guide wire channel 364. Tabs 368 facilitate the
placement of guide wire 301 by aiding the user in aligning the
guide wire with guide wire channel 364. In addition, working
catheter 303 is loaded into axial drive assembly 324 by placing the
working catheter into working catheter channel 366. As will be
described in more detail below, once the guide wire and working
catheter are positioned within guide wire channel 364 and working
catheter channel 366, respectively, engagement surfaces of guide
wire axial drive mechanism 350 and working catheter axial drive
mechanism 352 are brought into engagement with the guide wire and
working catheter respectively.
[0063] Both top deck 354 and central portion 360 of base plate 318
are shaped to define a recess 374. Working catheter channel 366
includes an opening 376 located within recess 374. Recess 374
allows opening 376 to be closer to y-connector 338 and also closer
to the entry incision in the patient allowing working catheter 303
to be advanced farther into the patient's vascular system than if
opening 376 were located further away from y-connector 338 or the
entry incision. As can be seen in FIG. 4, working catheter 303
includes a hub 305 at its proximal end that is too large to fit
through opening 376. Thus, the closer that opening 376 is to
y-connector 338 and to the entry incision the further working
catheter 303 can be advanced into the patient's vascular
system.
[0064] Cassette 300 also includes a rotational drive assembly 326.
Rotational drive assembly 326 includes a rotational drive
mechanism, shown as guide wire rotational drive mechanism 380, a
cover 384, and a journal 388. Guide wire rotational drive mechanism
380 includes a chassis 382 and an engagement structure 386.
Rotational drive assembly 326 is configured to cause guide wire 301
to rotate about its longitudinal axis. Engagement structure 386 is
configured to releasably engage guide wire 301 and to apply
sufficient force to guide wire 301 such that guide wire 301 is
allowed to rotate about its longitudinal axis while permitting
guide wire 301 to be moved axially by guide wire axial drive
mechanism 350.
[0065] In the embodiment shown, rotational drive assembly 326 is
supported within housing 316 such that rotation drive assembly 326
is permitted to rotate within housing 316. Engagement structure 386
applies sufficient force to guide wire 301 that the rotation of
rotation drive assembly 326 causes guide wire 301 to rotate about
its longitudinal axis as rotational drive assembly 326 rotates.
[0066] Chassis 382 includes a guide wire channel 390. Guide wire
channel 390 is positioned generally perpendicular to the top
surface of chassis 382 and runs the length of chassis 382 in the
longitudinal direction. A plurality of tabs 392 extend vertically
from the top surface of chassis 382 along guide wire channel 390.
In FIG. 5, cover 384 is shown in the open position. Cover 384 is
mounted to chassis 382 via hinge 394. Cassette 300 includes a
restraint structure that acts to restrain movement of the guide
wire when cover 384 is in the closed position. As shown, the
restraint structure includes a plurality of tabs 396 extending from
the lower surface of cover 384. The top surface of chassis 382
includes a plurality of recesses 398 configured to receive tabs 396
when cover 384 is in the closed position. Tabs 396 are positioned
such that when cover 384 is closed, tabs 396 are positioned over
guide wire channel 390 such that tabs 396 prevent guide wire 301
from falling out of guide wire channel 390 (i.e., restrains
movement of the guide wire in a direction perpendicular to the top
surface of chassis 382). In addition, the sidewalls of guide wire
channel 390 and the engagement surfaces of wheels 522 and 524
prevent or restrain movement of guide wire 301 in other directions
perpendicular to the longitudinal axis of guide wire 301. Thus,
tabs 392 and guide wire channel 390 hold guide wire 301 within
channel 390 during rotation of rotational drive assembly 326.
[0067] When cover 384 is in the open position, guide wire channel
390 is exposed allowing the user to load cassette 300 with a guide
wire. With cover 384 open, guide wire 301 is loaded into rotational
drive assembly 326 by placing the guide wire into guide wire
channel 390. Tabs 392 facilitate the placement of guide wire 301 by
aiding the user in aligning the guide wire with guide wire channel
390. As will be described in more detail below, once guide wire 301
is positioned within guide wire channel 390 engagement surfaces of
engagement structure 386 are brought into engagement with the guide
wire. In one embodiment, when the user activates controls (e.g.,
controls 16 located at workstation 14) to open cover 384,
rotational drive assembly 326 is automatically rotated such that
guide wire channel 390 is facing generally upward to allow for easy
loading or removal of guide wire 301.
[0068] In one embodiment, cassette 300 is a modular cassette that
allows various components of cassette 300 to be removed and/or
switched out with other components. In an exemplary embodiment, a
user may wish to control the guide wire using bedside system 12 and
to control the working catheter manually. In this embodiment, a
user may mount only guide wire axial drive mechanism 350 and
rotational drive assembly 326 within housing 316 of cassette 300.
In another exemplary embodiment, a user may wish to control the
working catheter using bedside system 12 and to control the guide
wire manually. In this embodiment, a user may mount only working
catheter drive mechanism 352 within housing 316 of cassette 300. In
another embodiment, cassette 300 may include additional locations
for mounting drive mechanisms for any type of additional catheter
devices that may be used during a procedure. For example, a user
may be able to couple drive mechanisms to cassette 300 to control
the movement and/or control of an intravascular ultrasound
catheter.
[0069] Referring to FIG. 6, cassette 300 is shown in the "loaded"
or "use" position. In the "loaded" position, y-connector support
assembly 322 is rotated downward such that y-connector 338 is
aligned with guide wire channel 364 of axial drive assembly 324.
The axial alignment allows guide wire 301 and working catheter 303
to be moved into and/or out of y-connector 338 via operation of
guide wire axial drive mechanism 350 and working catheter axial
drive mechanism 352. Cover 356 is shown in the closed position
overlying both the guide wire axial drive mechanism 350 and the
working catheter axial drive mechanism 352. As shown, cover 356
also covers guide wire channel 364 and working catheter channel
366. As such, cover 356 acts to prevent interference with the
various components of axial drive assembly 324 during use.
[0070] After cover 356 is moved to the closed position, handle 358
is rotated approximately 90 degrees such that a portion of handle
358 is positioned over cover 356. As will be discussed in greater
detail below, rotation of handle 358 to the closed position shown
in FIG. 6 causes the engagement surface of the guide wire axial
drive mechanism 350 and of the working catheter axial drive
mechanism 352 to move together engaging the guide wire and working
catheter, respectively.
[0071] In addition, when cassette 300 is moved to the "loaded"
position, cover 384 is moved to the closed position overlying
rotational drive mechanism 380 and guide wire channel 390 as shown
in FIG. 6. Like cover 356, cover 384 acts to prevent interference
with the various components of rotational drive assembly 326 during
use. In one embodiment, a user may activate controls (e.g.,
controls located at workstation 14) to cause the various components
of cassette 300 to move between the "loading" and "loaded"
positions. In addition, cassette 300 may also be configured to
allow the user to move the various components of cassette 300
between the "loading" and "loaded" positions manually.
[0072] Referring to FIG. 6, in the "loaded" or "use" configuration,
the longitudinal axis (and the internal lumen) of y-connector 338
is aligned with guide wire channel 364 of axial drive assembly and
with guide wire channel 390 of rotational drive assembly 326. This
alignment provides a path extending from the rear of cassette 300
through y-connector 338 into the guide catheter through which the
guide wire is advanced or retracted during axial movement of the
guide wire. In various embodiments, components of cassette 300,
including top deck 354, chassis 382, cover 356, and cover 384, may
be made from a transparent or translucent plastic.
[0073] Referring to FIG. 7, an exploded perspective view from above
of axial drive assembly 324 is shown. FIG. 7 generally depicts the
components of axial drive assembly 324. Guide wire axial drive
mechanism 350 and working catheter axial drive mechanism 352 are
positioned above base plate 318, and top deck 354 is fastened to
central portion 360 of base plate 318 above guide wire axial drive
mechanism 350 and working catheter axial drive mechanism 352. Thus,
guide wire axial drive mechanism 350 and working catheter axial
drive mechanism 352 are generally enclosed within a chamber defined
by top deck 354 and central portion 360 of base plate 318 when
axial drive assembly 324 is assembled. Top deck 354 includes a
plurality of apertures 362 to receive various portions of both
axial drive mechanism 350 and working catheter axial drive
mechanism 352.
[0074] Axial drive mechanism 350 includes a drive element 400, a
first roller assembly 402, a second roller assembly 404, and a
guide wire axial motion sensor assembly, shown as encoder assembly
406. First roller assembly 402 and second roller assembly 404 are
both mounted within a housing 416. Drive element 400 includes a
drive shaft 408, a drive wheel 410, a bearing 412, and a screw 414.
Drive shaft 408 is configured to engage second capstan 306 of motor
drive base 302 such that drive shaft 408 and drive wheel 410 rotate
in response to rotation of second capstan 306. First roller
assembly 402 includes an idler wheel or roller 418, a wheel housing
420, a bearing 422, and a spring 424.
[0075] Drive wheel 410 includes an outer or engagement surface 426,
and roller 418 includes an outer or engagement surface 428.
Generally, when guide wire axial drive mechanism 350 is placed in
the "use" or "engaged" position (shown in FIG. 10), guide wire 301
is positioned between drive wheel 410 and roller 418 such that
engagement surface 426 of drive wheel 410 and engagement surface
428 of roller 418 are able to engage the guide wire. In this
embodiment, engagement surface 426 and engagement surface 428
define a pair of engagement surfaces. The force applied to guide
wire 301 by engagement surface 426 and engagement surface 428 is
such that drive wheel 410 is able to impart axial motion to guide
wire 301 in response to the rotation of drive shaft 408 caused by
rotation of second capstan 306. This axial motion allows a user to
advance and/or retract a guide wire via manipulation of controls 16
located at workstation 14. Roller 418 is rotatably mounted within
wheel housing 420 and rotates freely as drive wheel 410 rotates to
drive guide wire 301. Spring 424 is biased to exert a force onto
wheel housing 420 causing roller 418 to engage the guide wire
against drive wheel 410. Spring 424 is selected, tuned, and/or
adjusted such that the proper amount of force is applied to guide
wire 301 by engagement surface 426 and engagement surface 428 in
the "engaged" position. In other embodiments, additional drive
elements may be added as necessary to impart axial motion to the
guide wire.
[0076] Second roller assembly 404 includes an idler wheel or roller
430, a wheel housing 432, a bearing 434, and a spring 436. Encoder
assembly 406 includes shaft 438, magnetic coupling 440, idler wheel
or roller 442, bearing 444, and a screw 446. Roller 430 includes an
outer or engagement surface 448 and roller 442 includes an outer or
engagement surface 450.
[0077] In the "engaged" position, guide wire 301 is positioned
between roller 430 and roller 442 such that engagement surface 448
of roller 430 and engagement surface 450 of roller 442 are able to
engage the guide wire. In this embodiment, engagement surface 448
and engagement surface 450 define a pair of engagement surfaces.
The force applied to guide wire 301 by engagement surface 448 and
engagement surface 450 is such that drive wheel 410 is able to pull
guide wire 301 past roller 430 and 442. In this way, the pair of
non-active or idle rollers 430 and 442 help support guide wire 301
and maintain alignment of guide wire 301 along the longitudinal
axis of cassette 300.
[0078] Roller 430 is rotatably mounted within wheel housing 432,
and roller 442 is rotatably mounted to shaft 438. Both rollers 430
and 442 are mounted to rotate freely as drive wheel 410 imparts
axial motion to guide wire 301. Spring 436 is biased to exert a
force onto wheel housing 432 causing roller 430 to engage guide
wire 301 against roller 442. Spring 436 is selected, tuned, and/or
adjusted such that the proper amount of force is applied to guide
wire 301 by engagement surface 448 and engagement surface 450 in
the "engaged" position to support the guide wire while still
allowing the guide wire to be moved axially by drive wheel 410. In
other embodiments, additional pairs of non-active or idler rollers
may be added as needed to provide proper support and alignment for
the guide wire. In one embodiment, spring 424 and spring 436 are
selected or adjusted such that the force applied to guide wire 301
by wheels 430 and 442 is approximately the same as the force
applied to guide wire 301 by wheels 410 and 418.
[0079] As shown in FIG. 7, engagement surface 426 of drive wheel
410 and engagement surface 428 of roller wheel 418 are configured
to increase the ability of the wheel to grip and to impart axial
motion to the guide wire. In particular, engagement surface 426 of
drive wheel 410 and engagement surface 428 of roller wheel 418 may
be textured (e.g., non-smooth, treaded, slotted, etc.) to increase
friction between the wheels and the guide wire. A particular
embodiment of a wheel for a robotic catheter system including a
textured engagement surface is shown in FIGS. 18, 19A and 19B,
discussed in more detail below. While FIG. 7, shows both wheels of
the front pair in guide wire axial drive mechanism 350 as textured,
any combination of wheels in guide wire axial drive mechanism may
be textured. For example, in other embodiments, only drive wheel
410 may be textured, or all four wheels (wheels 410, 418, 430, and
442) may be textured.
[0080] In various embodiments, the force applied to guide wire 301
by wheels 410, 418, 430 and 442 generated by springs 424 and 436
(e.g., the pinch force) may be variable or controllable. In various
embodiments, the pinch force may be varied to accommodate the use
of a variety of different types of guide wires. For example, if
cassette 300 is equipped with a guide wire having a rough or
textured outer surface, the pinch force generated by springs 424
and 436 may be decreased to ensure the proper amount of friction
between the wheels and the guide wire. In contrast, if cassette 300
is equipped with a guide wire having a smooth surface outer
surface, the pinch force generated by springs 424 and 436 may be
increased to ensure the proper amount of friction between the
wheels and the guide wire. In other embodiments, the pinch force
may be controlled to vary the performance of cassette 300 during a
procedure. For example, the pinch force may be increased to help
ensure that the guide wire remains in place (i.e., no axial motion
occurs) when the controls for guide wire axial motion are not be
actuated by the user and/or when the user is actuating controls for
a different percutaneous device.
[0081] The pinch force may be varied or controlled by the user in
various ways. For example, in one embodiment, cassette 300 may
include one or more actuator (e.g., a step motor) that receives a
control signal from controller 40 to adjust the force generated by
springs 424 and 436. In this embodiment, controls 16 may include a
control (e.g., a button, dial, touch screen icon, etc.) that allows
the user to alter the pinch force of guide wire axial drive
mechanism 350 from workstation 14. In another embodiment,
controller 40 may be configured to automatically adjust the pinch
force generated by springs 424 and 436 based upon the type of guide
wire that cassette 300 is equipped with. Controller 40 may prompt
the user to identify the type of guide wire via controls 16 (e.g.,
via a drop down menu, reading a bar code, etc.). In another
embodiment, catheter procedure system 10 may be configured to
automatically identify the type of guide wire that cassette 300 is
equipped with (e.g., via reading of an RFID tag associated with the
guide wire), and controller 40 may be configured to automatically
control the pinch force based on the automatically determined guide
wire type.
[0082] Encoder assembly 406 includes magnetic coupling 440 that
engages a magnetic encoder located within motor drive base 302. The
magnetic encoder is configured to measure an aspect (e.g., speed,
position, acceleration, etc.) of axial movement of the guide wire.
As roller 442 rotates, shaft 438 rotates causing magnetic coupling
440 to rotate. The rotation of magnetic coupling 440 causes
rotation of the magnetic encoder within motor drive base 302.
Because rotation of roller 442 is related to the axial movement of
guide wire 301, the magnetic encoder within motor drive base 302 is
able to provide a measurement of the amount of axial movement
experienced by guide wire 301 during a procedure. This information
may be used for a variety of purposes. For example, this
information may be displayed to a user at workstation 14, may be
used in a calculation of or estimated position of the guide wire
within the vascular system of a patient, may trigger an alert or
alarm indicating a problem with guide wire advancement, etc.
[0083] As shown in FIG. 7, first roller assembly 402 and second
roller assembly 404 are both mounted within a housing 416. Housing
416 provides a common support for first roller assembly 402 and
second roller assembly 404. As will be discussed in more detail
below, first roller assembly 402 and second roller assembly 404 are
moved away from drive wheel 410 and roller 442, respectively, when
axial drive assembly 324 is placed in the "loading" configuration.
This facilitates placement of guide wire 301 between the opposing
pairs of engagement surfaces of guide wire axial drive mechanism
350. Housing 416 allows first roller assembly 402 and second roller
assembly 404 to be moved together (e.g., in sync) away from drive
wheel 410 and roller 442, respectively, when axial drive assembly
324 is placed in the "load" configuration.
[0084] Axial drive assembly 324 also includes working catheter
axial drive mechanism 352. Working catheter axial drive mechanism
352 includes a drive element 452 and a working catheter axial
motion sensor assembly, shown as working catheter encoder assembly
454. Drive element 452 includes a drive shaft 456, a drive wheel
458, a bearing 460, and a screw 462. Drive shaft 456 is configured
to engage first capstan 304 of motor drive base 302 such that drive
shaft 456 and drive wheel 458 rotate in response to rotation of
first capstan 304. Encoder assembly 454 includes shaft 464, a
roller 466, an encoder linkage 468, a spring 470, and a magnetic
coupling 480.
[0085] Drive wheel 458 includes an outer or engagement surface 472
and roller 466 includes an outer or engagement surface 474. When
working catheter axial drive mechanism 352 is in the "engaged"
position, a working catheter is positioned between drive wheel 458
and roller 466, such that engagement surface 472 and engagement
surface 474 are able to engage working catheter 303. In this
embodiment, engagement surfaces 472 and 474 define a pair of
engagement surfaces. The force applied to working catheter 303 by
engagement surfaces 472 and 474 is such that drive wheel 458 is
able to impart axial motion to the working catheter in response to
the rotation of drive shaft 456 caused by rotation of first capstan
304. This axial motion allows a user to advance and/or retract a
working catheter via manipulation of controls located at
workstation 14. Roller 466 is rotatably mounted to shaft 464 and
rotates freely as drive wheel 458 rotates to drive the working
catheter.
[0086] As shown in FIG. 7, engagement surface 472 of drive wheel
458 is configured to increase the ability of the wheel to grip and
to impart axial motion to the working catheter. In particular,
engagement surface 472 of drive wheel 458 may be textured (e.g.,
non-smooth, treaded, slotted, etc.) to increase friction between
the wheel and the working catheter. A particular embodiment of a
wheel including a textured engagement surface is shown in FIGS. 18,
19A and 19B, discussed in more detail below. While FIG. 7 shows
drive wheel 458 with a textured outer surface and roller 466 with a
non-textured engagement surface 474, in other embodiments, both
drive wheel 458 and roller 466 may include textured outer
surfaces.
[0087] Spring 470 is coupled to a first end of linkage 468. The
second end of linkage 468 includes an aperture 476 that is
pivotally coupled to a post 478 extending from the inner surface of
top deck 354. Spring 470 is biased to exert a force on to linkage
468 causing linkage 468 to pivot about post 478 to force roller 466
to engage working catheter 303 against drive wheel 458. Spring 470
is selected, tuned, and/or adjusted such that the proper amount of
force is applied to working catheter 303 by engagement surfaces 472
and 474 in the "engaged" position to allow drive wheel 458 to
impart axial movement to the working catheter.
[0088] Encoder assembly 454 includes magnetic coupling 480 that
engages a magnetic encoder located within motor drive base 302. The
magnetic encoder is configured to measure an aspect (e.g., speed,
position, acceleration, etc.) of axial movement of the working
catheter. As roller 466 rotates, shaft 464 rotates causing magnetic
coupling 480 to rotate. The rotation of magnetic coupling 480
causes rotation of the magnetic encoder within motor drive base
302. Because rotation of roller 466 is related to the axial
movement of working catheter 303, the magnetic encoder within motor
drive base 302 is able to provide a measurement of the amount of
axial movement experienced by the working catheter during a
procedure. This information may be used for a variety of purposes.
For example, this information may be displayed to a user at
workstation 14, may be used in a calculation of or estimated
position of the working catheter within the vascular system of a
patient, may trigger an alert or alarm indicating a problem with
working catheter advancement, etc.
[0089] As will be discussed in more detail below, roller 466 is
moved away from drive wheel 458 when axial drive assembly 324 is
placed in the "loading" configuration. This facilitates placement
of the working catheter between the opposing pairs of engagement
surfaces of working catheter axial drive mechanism 352.
[0090] In one embodiment, cassette 300 and/or motor drive base 302
includes a locking mechanism that is configured to lock the
position of guide wire 301 during manipulation of the working
catheter 303 and to lock the position of working catheter 303
during manipulation of guide wire 301. In one embodiment, the
locking mechanism acts to increase the force applied to the guide
wire by the engagement surfaces when the working catheter is being
advanced and to increase the force applied to the working catheter
by the engagement surfaces when the guide wire is being
advanced.
[0091] Referring to FIGS. 7 and 8, top deck 354 includes a
plurality of cylindrical sleeves, first sleeve 482, second sleeve
484, and third sleeve 486, extending from the inner or lower
surface of top deck 354. Top deck 354 also includes a plurality of
cylindrical collars, first collar 488, second collar 490, and third
collar 492, extending from the upper surface of top deck 354.
Collar 488 is in axial alignment with sleeve 482. Collar 490 is in
axial alignment with sleeve 484. Collar 492 is in axial alignment
with sleeve 486. Each of the collars 488, 490, and 492 define an
aperture 362. In the embodiment shown, sleeve 482 and collar 488
are configured to receive working catheter drive element 452,
sleeve 484 and collar 490 are configured to receive guide wire
drive element 400, and sleeve 486 and collar 492 are configured to
receive guide wire encoder assembly 406. Apertures 362 provide
access to screws 414, 446, and 462 once top deck 354 is mounted
over axial drive assembly 324.
[0092] Top deck 354 includes a collar 494 aligned with and located
at the back end of guide wire channel 364. Collar 494 is configured
to receive front shaft 512 that extends from chassis 382 of
rotational drive assembly 326. Collar 494 is configured to allow
front shaft 512 (and consequently the rest of rotational drive
assembly 326) to rotate about the longitudinal axis of guide wire
channel 390 relative to axial drive assembly 324. In one
embodiment, rotational drive assembly 326 is able to rotate
relative to housing 316 of cassette 300 while axial drive assembly
324 does not rotate relative to housing 316. In another embodiment,
both rotational drive assembly 326 and axial drive assembly 324
rotate relative to housing 316 of cassette 300.
[0093] FIG. 8 is a bottom perspective view of cassette 300 showing
top deck 354 mounted above guide wire axial drive mechanism 350 and
working catheter axial drive mechanism 352. FIG. 8 shows working
catheter drive element 452, guide wire drive element 400, and guide
wire encoder assembly 406 received within sleeves 482, 484, and
486. A support structure 496 extends from the lower surface of top
deck 354. Spring 470 is coupled at one end to support structure 496
allowing spring 470 to compress and expanded between linkage 468
and support structure 496.
[0094] As shown, the lower end of drive shaft 408 includes a keyed
recess 498, and the lower end of drive shaft 456 includes a keyed
recess 500. Keyed recess 500 is one embodiment of first capstan
socket 310, and keyed recess 498 is one embodiment of second
capstan socket 312. Keyed recess 500 is configured to receive a
capstan, such as first capstan 304, and keyed recess 498 is
configured to receive a capstan, such as second capstan 306. First
capstan 304 and second capstan 306 are keyed to fit within keyed
recess 500 and 498 and to engage and turn drive shafts 456 and 408
upon rotation of the capstans.
[0095] As shown, magnetic coupling 440 of guide wire encoder
assembly 406 includes a circular array of magnets 504. Magnetic
coupling 480 of working catheter encoder assembly 454 includes a
circular array of magnets 506. Magnetic couplings 440 and 480
engage with magnetic encoders positioned within motor drive base
302. The magnetic encoders of motor drive base 302 are coupled to
appropriate electronics to detect and measure rotation of rollers
442 and 466 and to calculate axial motion of guide wire 301 and
working catheter 303 based on the measured rotations. While this
embodiment discloses the use of magnetic encoders to detect the
axial motion of the guide wire and working catheter, other sensors
may be used. In one embodiment, axial motion of the guide wire may
be detected by an optical sensor that detects movement of the guide
wire and/or working catheter by scanning the surface of the guide
wire and/or working catheter as it passes the optical sensor. In
one such embodiment, the optical sensor includes an LED light
source and a detector (e.g., a complementary metal oxide
semiconductor, other light detecting circuitry, etc.) that detects
light reflected off the surface of the guide wire and/or working
catheter, and the light detected by the detector is analyzed (e.g.,
by a digital signal processor) to determine movement of the guide
wire and/or working catheter. In another embodiment, the surface of
the guide wire and/or working catheter may include indicia that are
detected to determine axial movement of the guide wire. In other
embodiments, other types of sensors (e.g., resolvers, sychros,
potentiometers, etc.), may be used to detect movement of the guide
wire and/or working catheter.
[0096] Cassette 300 also includes a series of magnets 508
positioned below guide wire channel 364. Because, in at least some
embodiments, the guide wire is made from a magnetic material,
magnets 508 are able to interact with the guide wire. In this
embodiment, the magnetic attraction created by magnets 508 helps
the user position guide wire 301 during loading by drawing guide
wire 301 into guide wire channel 364. The magnetic attraction
created by magnets 508 also tends to hold guide wire 301 within
guide wire channel 364 during advancement and/or retraction of the
guide wire. Further, magnets 508 help to hold guide wire 301
straight (i.e., parallel to the longitudinal axis of guide wire
channel 364) to aid in the axial movement caused by guide wire
axial drive mechanism 350.
[0097] FIG. 9 shows a top view of axial drive assembly 324 in the
"loading" configuration with handle 358 (shown in broken lines)
rotated such that handle 358 is generally parallel to guide wire
channel 364. FIG. 10 shows a top view of axial drive assembly 324
in the "loaded" or "use" configuration with handle 358 rotated such
that it is generally perpendicular to guide wire channel 364.
Generally, when handle 358 is moved from the position of FIG. 10 to
the position of FIG. 9, the engagement surfaces of both guide wire
axial drive mechanism 350 and working catheter axial drive
mechanism 352 are moved away from each other increasing the space
between the pairs of wheels in the drive mechanisms. This provides
sufficient space between the wheels of each drive mechanism to
allow the user to place guide wire 301 and working catheter 303
into the channels between the wheels. Generally, as handle 358 is
moved from the position of FIG. 9 to the position of FIG. 10, the
engagement surfaces of both guide wire axial drive mechanism 350
and working catheter axial drive mechanism 352 are moved toward
each other bringing the engagement surfaces of each drive mechanism
into engagement with guide wire 301 or working catheter,
respectively.
[0098] In the embodiment shown, handle 358 is coupled to a shaft
357. Shaft 357 includes a cam section 359 and housing 416 includes
a cam surface 417. As handle 358 rotates from the position shown in
FIG. 9 to the position shown in FIG. 10, cam section 359 of shaft
357 moves along cam surface 417 causing housing 416 to move toward
guide wire 301. This motion engages guide wire 301 between drive
wheel 410 and roller 418 and between roller 430 and roller 442.
When handle 358 is brought into the position of FIG. 10, springs
424 and 436 are compressed to the proper tension to allow drive
wheel 410 to move guide wire 301 axial along its longitudinal
axis.
[0099] In addition, housing 416 includes a tab 419 that is coupled
to linkage 468. Thus, linkage 468 rotates about post 478 when
housing 416 is moved to the position shown in FIG. 9. This movement
draws roller 466 away from working catheter drive wheel 458. When,
housing 416 is moved to the position shown in FIG. 10, roller 466
is moved toward catheter drive wheel 458 such that the engagement
surfaces of roller 466 and drive wheel 458 engage working catheter
303. In one embodiment, cassette 300 is configured to allow the
user to move the axial drive assembly 324 between the "use" and
"loading" positions via manipulation of controls at workstation 14.
Cassette 300 may also be configured to allow the user to move the
axial drive assembly 324 between the "use" and "loading" position
manually.
[0100] FIGS. 11 and 12 show a perspective view of rotational drive
assembly 326 showing cover 384 in the open position. Rotational
drive assembly 326 includes rotational drive mechanism 380, chassis
382, an engagement structure 386, and a disengagement assembly 510.
Chassis 382 fits over engagement structure 386 and provides
mounting for various components of rotational drive assembly 326.
Chassis 382 includes a front shaft 512 and a rear shaft 514. As
discussed above, front shaft 512 is rotatably received within
collar 494 of top deck 354, and rear shaft 514 is rotatably
received within collar 516 such that rotational drive mechanism 380
is able to rotate relative to journal 388. As shown, collar 516
extends through and is supported by journal 388 such that rear
shaft 514 rotates within collar 516 as rotational drive mechanism
380 is rotated. Collar 516 rests within a recess or slot formed
within journal 388. In another embodiment, rear shaft 514 may be in
direct contact with journal 388 such that rear shaft 514 rotates
within the recess or slot of journal 388 as rotational drive
mechanism 380 is rotated. Guide wire channel 390 extends the length
of chassis 382 through both front shaft 512 and rear shaft 514.
[0101] Rotational drive mechanism 380 includes rotation bevel gear
518 that engages a drive gear 520. Bevel gear 518 is rigidly
coupled to front shaft 512 of chassis 382 such that rotation of
bevel gear 518 rotates chassis 382. Drive gear 520 is coupled to a
rotational actuator positioned in motor drive base 302 and engages
bevel gear 518. Rotation of the rotational actuator in motor drive
base 302 causes drive gear 520 to rotate which causes bevel gear
518 to rotate which in turn causes rotational drive mechanism 380
to rotate. Rotational drive mechanism 380 is allowed to rotate
about the longitudinal axis of guide wire channel 390 via the
rotatable connections between front shaft 512 and top deck 354 and
between rear shaft 514 and journal 388. Bevel gear 518 further
includes a slot 519 in axial alignment with guide wire channel 390.
Slot 519 allows the user to place guide wire 301 into guide wire
channel 390 by dropping it in vertically as opposed to threading it
through bevel gear 518. In one embodiment, rotational drive
assembly 326 is equipped with one or more sensors that are
configured to measure an aspect (e.g., speed, position,
acceleration, etc.) of rotation of the guide wire and/or any other
structure of rotational drive assembly 326. The sensors that
measure rotation of the guide wire may include magnetic encoders
and/or optical sensors as discussed above regarding the sensors
that measure axial motion of the guide wire and/or working
catheter. However, any suitable sensor (e.g., resolvers, sychros,
potentiometers, etc.) may be used to detect rotation of the guide
wire.
[0102] Referring to FIG. 12, engagement structure 386 is shown
according to an exemplary embodiment. As shown, engagement
structure 386 includes four pairs of idler wheels or rollers. Each
pair of rollers includes a fixed wheel 522 and an engagement wheel
524. Fixed wheels 522 are rotatably coupled to chassis 382 via
fixation posts 530. Each engagement wheel 524 is part of an
engagement wheel assembly 523. Each engagement wheel assembly 523
includes a pivoting body, shown as pivot yoke 532, and a spring
536. Each engagement wheel is mounted to pivot yoke 532 via a
mounting post 538. Each pivot yoke 532 is pivotally coupled to
chassis 382 via fixation posts 534.
[0103] Each fixed wheel 522 includes an outer or engagement surface
526 and each engagement wheel 524 includes an outer or engagement
surface 528. Generally, FIG. 12 shows engagement structure 386 in
the "use" or "engaged" position. In the "engaged" position, guide
wire 301 is positioned between fixed wheels 522 and engagement
wheels 524 such that engagement surfaces 526 and 528 are able to
engage guide wire 301. In this embodiment, engagement surface 526
and engagement surface 528 of each pair of rollers define a pair of
engagement surfaces. The force applied to guide wire 301 by
engagement surfaces 526 and 528 is sufficient to cause the guide
wire to rotate about its longitudinal axis as rotational drive
assembly 326 is rotated. Further, the force applied to guide wire
301 by engagement surfaces 526 and 528 is also sufficient to allow
the guide wire to be moved axially by guide wire axial drive
mechanism 350. While FIG. 12 shows wheels 522 and 524 having
substantially smooth outer engagement surfaces, in other
embodiments, wheels 522 and 524 may include a textured engagement
surface as shown in FIGS. 18, 19A and 19B, discussed in more detail
below.
[0104] Springs 536 are biased to exert a force onto pivot yokes 532
causing each engagement wheel 524 to engage the opposite fixed
wheel 522. The generally L-shape of pivot yoke 532 allows springs
536 to be aligned with the longitudinal axis of guide wire 301 and
still cause engagement between engagement wheels 524, fixed wheels
522, and the guide wire. This allows the lateral dimension of
rotational drive assembly 326 to be less than if springs 536 were
positioned perpendicular to the longitudinal axis of the guide
wire. Springs 536 are selected, tuned, and/or adjusted such that
the proper amount of force is applied to the guide wire by
engagement surfaces 526 and 528 in the "engaged" position.
[0105] Cassette 300 also includes a series of magnets 540 located
beneath guide wire channel 390. Because, in at least some
embodiments the guide wire is made from a magnetic material,
magnets 540 are able to interact with the guide wire. In this
embodiment, the magnetic attraction created by magnets 540 helps
the user position guide wire 301 during loading by drawing guide
wire 301 into guide wire channel 390. The magnetic attraction
created by magnets 540 also tends to hold guide wire 301 within
guide wire channel 390 during advancement and/or retraction of the
guide wire. Further, magnets 540 help to hold guide wire 301
straight (i.e., parallel to the longitudinal axis of guide wire
channel 390) to aid in the axial movement caused by guide wire
axial drive mechanism 350.
[0106] Rotational drive assembly also includes a disengagement
assembly 510. Disengagement assembly 510 includes a stepped collar
542, a base plate 544, and a spring 546. Stepped collar 542 is
coupled to base plate 544, and spring 546 is coupled at one end to
chassis 382 and at the other end to base plate 544. Stepped collar
542 includes a slot 548 in axial alignment with guide wire channel
390. Like slot 519, slot 548 allows the user to place guide wire
301 into guide wire channel 390 by dropping it in vertically as
opposed to threading it through stepped collar 542. Base plate 544
includes a plurality of engagement arms 550 that extend generally
perpendicular to the plane defined by base plate 544.
[0107] Generally, disengagement assembly 510 allows engagement
wheels 524 to be moved away from fixed wheels 522. Referring to
FIGS. 13 and 14, FIG. 14 shows a top view of rotational drive
assembly 326 in the "loading" configuration, and FIG. 13 shows a
top view of rotational drive assembly 326 in the "loaded" or "use"
configuration. To cause engagement wheels 524 to disengage from
guide wire 301, an axially directed force (depicted by the arrow in
FIG. 14) is applied to stepped collar 542. This causes base plate
544 to move toward the front of cassette 300 in the direction of
the arrow. As base plate 544 moves forward, spring 546 is
compressed, and engagement arms 550 are brought into contact with
pivot yokes 532. The contact between engagement arms 550 and pivot
yokes 532 causes springs 536 to be compressed, and pivot yokes 532
pivot about fixation posts 534. As pivot yokes 532 pivot,
engagement wheels 524 are drawn away from fixed wheels 522. As
shown in FIG. 14, this provides sufficient space between engagement
wheels 524 and fixed wheels 522 to allow the user to place guide
wire 301 into guide wire channel 390.
[0108] When the axial force is removed from stepped collar 542,
engagement wheels 524 move from the position shown in FIG. 14 to
the "engaged" position shown in FIG. 13. When the axial force is
removed, spring 546 and springs 536 are allowed to expand causing
engagement arms 550 to disengage from pivot yokes 532. Pivot yokes
532 pivot counter-clockwise about fixation posts 534, bringing
engagement wheels 524 back toward guide wire channel 390 causing
engagement surfaces 526 of fixed wheels 522 and engagement surfaces
528 of engagement wheels 524 to engage guide wire 301.
[0109] In one embodiment, a user may activate controls located at
workstation 14 to cause rotational drive assembly 326 to move
between the "use" position and the "loading" position. In this
embodiment, rotational drive assembly 326 is automatically rotated
such that guide wire channel 390 is facing generally upward to
allow for easy loading or removal of the guide wire. In the
embodiment shown, chassis 382 rotates relative to stepped collar
542. In this embodiment, when rotational drive assembly 326 is in
the "loading" position, a path defined by the engagement surfaces
of engagement structure 386 and guide wire channel 390 align with
slot 548 of stepped collar 542. Motor drive base 302 may also
include a structure (e.g., two rods, etc.) that applies the axial
force to stepped collar 542 in response to a user's activation of
controls located at workstation 14. The structure applies the axial
force to the stepped collar 542 to cause engagement structure 386
to disengage from the guide wire. Next, cover 384 is moved from the
closed position to the open position allowing the user to access
guide wire channel 390 to either remove or install the guide wire.
In one embodiment, cassette 300 and/or motor drive base 302
includes motors or other actuators that cause the covers of
cassette 300 to open in response to a user's activation of controls
at workstation 14.
[0110] FIG. 15 shows a cross-sectional view of rotational drive
assembly 326 as indicated by the corresponding sectional line in
FIG. 6. FIG. 15 depicts guide wire 301 within guide wire channel
390. As shown in FIG. 15, when cover 384 is in the closed position,
tab 396 rests over guide wire channel 390. As shown in FIG. 15, tab
396 helps hold guide wire 301 in guide wire channel 390 by
restricting movement of guide wire 301 in a direction perpendicular
to the plane defined by base plate 544 (this direction of
restriction is the vertical direction in the orientation of FIG.
15). Guide wire 301 is engaged on one side by engagement surface
526 of fixed wheel 522 and on the other side by engagement surface
528 of engagement wheel 524.
[0111] In a further embodiment a drive mechanism is provided which
optimizes the manner in which axial and rotational motion is
imparted to a robotic catheter device. In this regard, for ease of
description the term catheter device is used in an expansive sense
to encompass not only guide catheters and working catheters such as
those used to deploy angioplasty balloons and stents but also the
guide wires used in conjunction with the guide and working
catheters regardless of the fact that guide wires are clearly not a
type of catheter. This drive mechanism employs tires mounted on
hubs as described above in Paragraph [0125] and also referred to as
wheels to impart both axial and rotational motion to catheter
devices (used in a sense analogous to percutaneous device and
therefore encompassing guide wires) which optimize the simultaneous
delivery of both types of motion. This optimization involves
balancing the drive and resistance features of both the tires used
to impart the axial motion and the tires used to impart rotational
motion. Thus it is desirable that the tires imparting axial motion
be efficient at doing so without creating undue resistance to
rotational motion and that the tires imparting rotational motion be
efficient at doing so without creating undue resistance to axial
motion.
[0112] The drive mechanism includes a tire of a drive wheel and a
tire of an idler wheel which interact with each other and the
catheter device to cause it to move along its axis. Each of the
tires has an engagement surface which interacts with a catheter
device. These engagement surfaces are free of any gripping features
which run perpendicular to the axis of the catheter device. This is
in contrast to providing them with slits which do run perpendicular
to the axis of the catheter device as described above in Paragraphs
[0119-0121]. It is expected that such perpendicular features will
impart resistance to rotational motion which out weights any
benefit to imparting axial motion in a mechanism which optimizes
the simultaneous impartation of both motions.
[0113] The drive mechanism also includes a set of tires which are
part of wheels of a rotational drive assembly which cause the
catheter device to rotate about its axis. These tires each have an
engagement surface which interacts with the catheter device and
which has a gripping feature which runs perpendicular to the axis
of the catheter device. This feature enhances the ability of these
tires to impart rotational motion to the catheter device without an
objectionable increase in the resistance to axial motion in a
mechanism which optimizes the simultaneous impartation of both
motions.
[0114] A useful perpendicular gripping feature is a series of slits
in the outside circumference of such a tire. In one embodiment
these slits are of the type described below in Paragraphs
[0119-0121]. One embodiment features these slits being present on
the engagement surfaces of both of the tires.
[0115] One embodiment involves using tires on the rotational drive
assembly wheels which are relatively soft compared to the range of
harnesses available in polymer wheels. It is expected that the
softer wheels will provide better rotational or torsional gripping
of the catheter device when imparting rotational motion but will
still offer low resistance to axial motion. In one embodiment the
tires have a durometer hardness of less than about 85 A.
[0116] One embodiment involves having the tires of the rotational
drive assembly wheels apply a substantially lighter pinch force to
the catheter device than do the drive wheel tire and idler wheel
tire. In one embodiment the drive wheel tire and the idler wheel
tire apply a pinch force of about 9 pounds to the catheter device
and the tires of rotational drive assembly wheels apply a pinch
force of about 1.25 pounds to the catheter device. In this regard,
the reference is to the pinch force applied by each set of
rotational drive assembly tires as opposed to the aggregate pinch
force of all the sets which may be part of the rotational drive
assembly.
[0117] In one embodiment the rotational drive assembly has three
sets of wheels and associated tires as opposed to the four
illustrated in FIGS. 11-14 and 23. The number of sets is a function
of the efficiency of each set in imparting rotational motion to the
catheter device and thus as the efficiency of each set is improved,
for instance by perpendicular slits, it may be possible to reduce
the number of sets and still achieve acceptable performance.
[0118] In one embodiment the engagement surfaces of both the drive
wheel tire and the idler wheel tire have a durometer hardness of at
least about 95 A. It has been observed that when both engagement
surfaces are relatively hard the efficiency of imparting axial
motion is enhanced, particularly when the surface of the catheter
device is wet. In use the outer surface of catheter devices,
especially guide wires, may become covered with liquids which can
affect their interactions with drive and idler tires and that this
may be addressed by both having hard engagement surfaces.
[0119] In one embodiment the auxiliary encoder wheel tire and an
encoder idler wheel tire which interacts with the auxiliary encoder
wheel tire apply a substantially lighter pinch force to the
catheter device than do the drive wheel tire and idler wheel tire.
It is expected that the encoder assembly will be able to provide a
reasonably precise measure of the axial motion of the catheter
device while offering less resistance to axial motion with a
lighter pinch force. In one embodiment the drive wheel tire and the
idler wheel tire apply a pinch force of about 9 pounds to the
catheter device and the auxiliary encoder wheel tire and an encoder
idler wheel tire apply a pinch force of about 0.75 pounds to the
catheter device.
[0120] In one embodiment the radial thickness of both the drive
wheel tire and the idler wheel tire is reduced. It is expected that
this will give performance equivalent to or better harder tires
with greater radial thickness. In one embodiment the outside
diameter of the tires is maintained constant so it is necessary to
increase the outside radius of the hubs on which the two tires are
mounted. In one embodiment the radial thickness of both the drive
wheel tire and the idler wheel tire is between about 0.03 and 0.06
inches. The reduction of radial thickness allows a reduction in the
hardness of the engagement surface of the tires and this, in turn,
is expected to reduce the rolling resistance of the tires. In one
embodiment the engagement surface of each the drive wheel tire and
the idler wheel tire has a durometer hardness of less than about 50
D.
[0121] In one embodiment the drive mechanism is involved in
imparting axial and rotational motion to a guide wire, which in a
broad sense can be thought of as a catheter device (It typically
functions in conjunction with a guide catheter or a working
catheter or both to accomplish a given medical procedure). The
guide wire is the type of percutaneous device which is most
typically subjected to the simultaneous application of both axial
motion and rotational motion. In one embodiment the guide wire has
a diameter between about 0.014 inches and 0.038 inches. The 0.014
inch diameter guide wire is commonly used in conjunction with a
robotic catheter system.
[0122] In yet another alternative embodiment the drive mechanism
makes use of composite tires on its various wheels. This allows a
separation between the engagement surface properties and the
overall resilience experienced by the catheter device, such as a
guide wire, which is being driven. The drive mechanism has a drive
wheel tire and an idler wheel tire which interact with each other,
each of which has an engagement surface which interacts with a
catheter device to cause it to move along its axis and a set of
rotational drive assembly wheel tires, each of which has an
engagement surface which interacts with a catheter device to cause
it to rotate about its axis. One or more of the tires has a
composite structure in which a material or structure of higher
resilience is interposed between its engagement surface and the hub
on which it is mounted. In one embodiment it is the rotational
drive assembly wheel tires which have the composite structure. In
one embodiment interposed material or structure of higher
resilience is a pressurized fluid, a high resistance o-ring or a
canted coil spring. If pressurized fluid, such as air, is to be
used some structure will be needed to contain it but such
structures be readily apparent to those of ordinary skill in the
art. One approach is to provide the tires with side walls and to
mount them to the hub in a manner analogous to that in mounting
automotive tires to their wheels. Suitable canted springs are sold
by BalSeal. It is expected that this composite tire approach would
reduce the rolling resistance and, in the case of the rotational
drive assembly wheel tires, this would be without a loss in the
torsional engagement.
[0123] FIG. 16 shows a cross-sectional view of axial drive assembly
324 as indicated by the corresponding sectional line in FIG. 6.
FIG. 16 depicts guide wire 301 within channel 364. Guide wire 301
is engaged on one side by engagement surface 426 of drive wheel 410
and on the other side by engagement surface 428 of roller 418.
[0124] Under certain circumstances, it may be desirable to
disconnect rotational drive assembly 326 from cassette 300.
Referring to FIGS. 17A-17C, cassette 300 may be configured to allow
rotational drive assembly 326 (shown schematically by broken lines
in FIGS. 17A-17C) to be disconnected from cassette 300. In one such
embodiment, cassette 300 includes journal 388, and rotational drive
mechanism 380 is rotatably coupled to journal 388. In this
embodiment, journal 388 is releasably coupled to housing 316 such
that both journal 388 and rotational drive mechanism 380 may be
removed from housing 316 without removing the guide wire from the
patient and/or without removing cassette 300 from base 302. In one
such embodiment, following release of journal 388 from housing 316,
the user may remove (e.g., pull, slide, etc.) both journal 388 and
rotational drive mechanism 380 over the proximal end of the guide
wire.
[0125] In one embodiment, journal 388 includes a slot 552, and base
plate 318 includes a release button 554. Release button 554 is
coupled to ramp 556, and ramp 556 includes wedge-shaped end 558. As
shown in FIG. 17A, wedge-shaped end 558 passes through slot 552 to
couple journal 388 to base plate 318. When a downward force is
applied to release button 554, wedge-shaped end 558 is allowed to
disengage from slot 552 allowing rotational drive assembly 326 and
journal 388 to disconnect from base plate 318.
[0126] Next, rotational drive assembly 326 is disengaged from guide
wire 301. As discussed above, regarding FIGS. 13 and 14, by
applying an axial force to stepped collar 542, engagement structure
386 disengages from the guide wire. Once engagement structure 386
is disengaged from guide wire 301, the rotational drive assembly
326 may be moved over the proximal end of the guide wire while the
guide wire slides freely though guide wire channel 390. Removal of
rotational drive assembly 326 from cassette 300 may be necessary
if, for example, bedside system 12 loses power preventing motor
drive base 302 from placing rotational drive assembly into the
"loading" configuration. In this case, removal of rotational drive
assembly 326 allows the user to either remove the guide wire and
working catheter from the patient manually or to complete the
procedure manually.
[0127] Referring to FIGS. 18, 19A and 19B, a wheel (e.g., drive
wheel 410) for a drive mechanism of a robotic catheter system is
shown according to an exemplary embodiment. As shown in FIGS. 18,
19A and 19B, engagement surface 426 of drive wheel 410 is
configured to increase the ability of the wheel to grip and to
impart axial motion to the guide wire. Engagement surface 426 of
drive wheel 410 is textured (e.g., non-smooth, treaded, slotted,
slitted, etc.) to increase friction between the wheel and the guide
wire. In particular, in the embodiment shown, drive wheel 410
includes a plurality of slits 600 formed in the outer layer of the
material of drive wheel 410. Slits 600 act to provide better grip
between the wheel and the guide wire which provides for improved
transmission of motion from the wheel to the guide wire and also
decreases the chance that slippage will occur between the drive
wheel and the guide wire. While the description of FIGS. 18-19B
relates to drive wheel 410, it should be understood that any wheel
of cassette 300 can be configured as discussed in relation to drive
wheel 410. Accordingly, wheels 522 and 524 of rotational drive
assembly 326 may have an engagement surface that is textured as
described with wheels 410 and 418. Such that only one or both of
wheels 522 and 524 may textured, or that only certain of wheels 522
are textured and/or only certain of wheels 524 are textured or only
some combination of some but not all of wheels 522 and 524 are
textured. It is also contemplated that some of the wheels 522 and
524 may be textured but with different tread configurations or with
a different engagement surface material than other wheels 522 and
524. Applying a different engagement surface characteristic to
different wheels may provide greater overall gripping, drive and
rotational performance for the system under certain operating
conditions. Further as noted, the texture of certain wheels 522 and
524 may be the same or different than the texture wheels 410 and
418 depending on the gripping, rotational and drive performance
desired. The specific desired arrangement of engagement surfaces of
the wheels may depend on the type of guide wire or working catheter
or catheter that is being manipulated by the system as well as the
type of procedure being employed on the patient.
[0128] As shown in FIG. 18, each slit 600 has substantially the
same size, shape, etc., as the other slits 600. However, in other
embodiments, slits 600 may having varying sizes, shapes, etc. In
the embodiment shown, slits 600 are substantially linear and are
positioned substantially parallel to the central axis (e.g., the
axis of rotation) of drive wheel 410. Slits 600 extend the entire
axial dimension of engagement surface 426, and, in this
arrangement, slits 600 are substantially parallel to each other. In
other embodiments, slits 600 may be other shapes or positioned in
other configurations relative to engagement surface 426. For
example, slits 600 may be curved having a component that extends in
the circumferential direction along engagement surface 426. In
other embodiments, slits 600 may have multiple segments positioned
at angles relative to each other (e.g., a zigzag pattern).
[0129] Referring to FIGS. 19A and 19B, a top view of drive wheel
410 is shown. Slits 600 of drive wheel 410 are spaced at even
intervals around drive wheel 410 and are substantially symmetric
about the radial centerline of the slit. In various embodiments,
the angle A between the radial centerlines of adjacent slits 600
may be selected to vary the gripping characteristic of the wheel.
In various exemplary embodiments, the angle A between radial
centerlines of adjacent slits 600 may be between about 5 degrees
and about 20 degrees, specifically between about 10 degrees and
about 15 degrees, and more specifically between about 11 degrees
and 13 degrees. In the exemplary embodiment shown in FIGS. 18-19B,
drive wheel 410 includes 30 slits 600 evenly spaced such that angle
A is about 12 degrees.
[0130] The depth of slits 600 below the outer surface 426, shown as
dimension D in FIG. 19B, may be selected to vary the gripping
characteristics of wheel 410. In various embodiments, the depth of
slits 600 may be selected to be between about 1 percent and about
10 percent of the diameter of wheel 410, specifically between about
1 percent and about 7 percent of the diameter of wheel 410, and
more specifically between about 1.5 percent and about 6.4 percent
of the diameter of wheel 410. In a specific embodiment, the
diameter of wheel 410 is about 0.63 inches, and the depth D of
slits 600 is between about 0.01 inches and about 0.04 inches.
[0131] The circumferential dimension of slits 600, shown as
dimension W in FIG. 19B, may be selected to vary the gripping
characteristics of wheel 410. In various embodiments, the
circumferential dimension W of slits 600 may be selected to be
between about 0 percent and about 10 percent of the circumference
of wheel 410, specifically between about 0 percent and about 3
percent of the circumference of wheel 410, and more specifically
between about 0 percent and about 1 percent of the circumference of
wheel 410.
[0132] Further, the material of drive wheel 410 may be selected to
vary the gripping characteristics of wheel 410. In one embodiment,
drive wheel 410 may be made from a polymer material. In one
embodiment, drive wheel 410 may be made from a thermoplastic
polyurethane elastomer. In one specific embodiment, drive wheel 410
may be made from Texin RxT85A manufactured by Bayer
MaterialScience.
[0133] In various embodiments, the hardness of the material of
drive wheel 410 may be selected to vary the gripping
characteristics of wheel 410. In various embodiments, the shore
hardness of the material of drive wheel 410 is between about 10 A
and about 100 A, specifically between about 50 A and about 100 A,
and more specifically between about 75 A and about 95 A. In one
specific embodiment, drive wheel 410 is made from a material having
a shore hardness of about 85 A.
[0134] In one embodiment, drive wheel 410 may be formed from a
molded piece of polymer material having a smooth outer surface.
Drive wheel 410 may then be coupled to a hub 602 of a cylindrical
pin or shaft. Following attachment to hub 602, slits 600 are
created in the outer surface of drive wheel 410 using a cutting or
slitting tool to produce slits 600 of the desired size, shape and
positioning.
[0135] Drive wheel 410 may be attached to the hub in a variety of
ways. In various embodiments, drive wheel 410 is coupled to hub 602
such that rotation of the shaft is transmitted to drive wheel 410
without slippage occurring between drive wheel 410 and hub 602. In
one embodiment, drive wheel 410 is shaped as a ring having a
central opening, and drive wheel 410 is mounted to hub 602 by
stretching the material of drive wheel 410 and placing drive wheel
410 over hub 602 such that hub 602 is received in the central
opening of drive wheel 410. In this embodiment, the elasticity of
the material of drive wheel 410 is sufficient to firmly attach
drive wheel 410 to hub 602 and to prevent movement of drive wheel
410 relative to hub 602 during rotation.
[0136] In other embodiments, drive wheel 410 may be attached to hub
602 by other means. In one embodiment, drive wheel 410 may be
welded or bonded to hub 602, and, in another embodiment, drive
wheel 410 may be attached to hub 602 using an adhesive. In yet
another embodiment, drive wheel 410 may be coupled to hub 602 using
mechanical attachment elements. For example, the outer
circumferential surface of hub 602 may be formed with a series of
posts, and the inner surface of drive wheel 410 may be formed with
a series of recesses that receive the posts of hub 602.
[0137] Referring to FIGS. 20-23, a structure or clip, shown as
wheel separator clip 610, is depicted according to an exemplary
embodiment. Separator clip 610 is configured to engage rotational
drive assembly 326 in a manner that causes each pair of wheels 522
and 524 to be held in the disengaged, "loading" position shown in
FIG. 14. As noted above, in some embodiments, wheels 522 and 524 of
rotational drive assembly 326 may be made from a deformable,
polymer material. Further, because springs 536 act to bias wheels
522 and 524 to the engaged position shown in FIG. 13, when cassette
300 is not in use, wheels 522 and 524 will tend to assume the
engaged position in which the outer surfaces of each wheel are in
contact with each other. If cassette 300 is not used for a
substantial period of time (e.g., during storage following
manufacture, during storage between procedures, etc.), the constant
contact between wheels 522 and 524 under the influence of springs
536 may cause deformation of wheels 522 and 524. For example,
flattened sections may be formed along the outer surface of wheels
522 and 524 at the location of the contact between the wheels.
Separator clip 610 may be used to engage rotational drive assembly
326 to resist the biasing force of springs 536 in order to hold
wheels 522 and 524 in the "disengaged" position when cassette 300
is not in use. In this manner, separator clip 610 acts to prevent
the deformation that wheels 522 and 524 may be susceptible to if
the they are allowed to remain in the engaged position for an
extended period of time.
[0138] Referring to FIG. 20, an exploded view of separator clip 610
and rotational drive assembly 326 is shown. Separator clip 610
includes a body 612, a pair of upper walls 614 positioned
substantially perpendicular to and extending from body 612, a pair
of gripping surfaces 616, and a handle tab 618. Separator clip 610
also includes at least one arm 620 positioned to and extending from
body 612. In an exemplary embodiment, separator clip 610 includes
one arm 620 for each pair of wheels 522 and 524 in rotational drive
assembly 326, and in the particular embodiment shown in FIG. 21,
separator clip 610 includes four arms 620 corresponding to the four
pairs of wheels 522 and 524 of rotational drive assembly 326.
[0139] Separator clip 610 is shown engaged to rotational drive
assembly 326 in FIG. 22, and the dotted lines 622 in FIG. 20
indicate the position of engagement between arms 620 of separator
clip 610 and rotational drive assembly 326 when separator clip 610
is coupled to the rotational drive assembly. As indicated in FIG.
20, arms 620 of separator clip 610 are positioned between
engagement arms 550 of base plate 544 and pivot yokes 532 of each
wheel assembly 523 of rotational drive assembly 326. When separator
clip 610 is engaged with rotational drive assembly 326, upper walls
614 are positioned in contact with the upper outer surface of cover
384 of rotational drive assembly 326. To hold and manipulate
separator clip 610, the user may grasp gripping surfaces 616 and/or
handle tab 618.
[0140] Referring to FIG. 23, a bottom view of rotational drive
assembly 326 is shown with separator clip 610 coupled to rotational
drive assembly 326. Each arm 620 of separator clip 610 is
positioned between one engagement arm 550 of base plate 544 and the
opposing pivot yoke 532. In this position, each arm 620 includes a
first surface, shown as the right-facing surface in FIG. 23, that
is in contact with engagement arm 550 and a second surface, shows
as the left-facing surface in FIG. 23, that is in contact with
pivot yoke 532. The contact of the opposing surfaces of each arm
620 with engagement arms 500 and pivot yokes 532 causes each spring
536 to be compressed. The compression of springs 536 in turn causes
each pivot yoke 532 to pivot about fixation post 534. As explained
in detail above regarding FIGS. 13 and 14, compression of springs
536 and the resulting pivoting of each pivot yoke 532 moves each
wheel 524 away from the opposing wheel 522. With separator clip 610
engaged between engagement arms 550 and pivot yokes 532, rotational
drive assembly 326 is held in the disengaged position such that
wheels 522 and 524 are not in contact with each other. In this
manner, separator clip 610 acts to prevent deformation of wheels
522 and 524 that may otherwise be caused by constant, long-term
contact between wheels 522 and 524. Prior to use of cassette 300,
separator clip 610 is disengaged from rotational drive assembly 326
allowing wheels 522 and 524 to move into engagement under the force
of springs 536.
[0141] Further modifications and alternative embodiments of various
aspects of the invention will be apparent to those skilled in the
art in view of this description. Accordingly, this description is
to be construed as illustrative only. The construction and
arrangements, shown in the various exemplary embodiments, are
illustrative only. Although only a few embodiments have been
described in detail in this disclosure, many modifications are
possible (e.g., variations in sizes, dimensions, structures, shapes
and proportions of the various elements, values of parameters,
mounting arrangements, use of materials, colors, orientations,
etc.) without materially departing from the novel teachings and
advantages of the subject matter described herein. Some elements
shown as integrally formed may be constructed of multiple parts or
elements, the position of elements may be reversed or otherwise
varied, and the nature or number of discrete elements or positions
may be altered or varied. The order or sequence of any process,
logical algorithm, or method steps may be varied or re-sequenced
according to alternative embodiments. Other substitutions,
modifications, changes and omissions may also be made in the
design, operating conditions and arrangement of the various
exemplary embodiments without departing from the scope of the
present invention.
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