U.S. patent application number 11/236770 was filed with the patent office on 2006-02-02 for navigation of remotely actuable medical device using control variable and length.
This patent application is currently assigned to Stereotaxis, Inc.. Invention is credited to Walter M. Blume, Raju R. Viswanathan.
Application Number | 20060025719 11/236770 |
Document ID | / |
Family ID | 35783385 |
Filed Date | 2006-02-02 |
United States Patent
Application |
20060025719 |
Kind Code |
A1 |
Viswanathan; Raju R. ; et
al. |
February 2, 2006 |
Navigation of remotely actuable medical device using control
variable and length
Abstract
A method of navigating a medical device includes determining the
location of a medical device at a point in an operating region in a
subject's body, the medical device being responsive to at least one
control variable to assume a desired configuration includes storing
information representative of the at least one control variable
being applied to the medical device at the point, and more
preferably storing information representative of the at least one
control variable and the device length.
Inventors: |
Viswanathan; Raju R.; (St.
Louis, MO) ; Blume; Walter M.; (St. Louis,
MO) |
Correspondence
Address: |
HARNESS, DICKEY, & PIERCE, P.L.C
7700 BONHOMME, STE 400
ST. LOUIS
MO
63105
US
|
Assignee: |
Stereotaxis, Inc.
|
Family ID: |
35783385 |
Appl. No.: |
11/236770 |
Filed: |
September 27, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11170764 |
Jun 29, 2005 |
|
|
|
11236770 |
Sep 27, 2005 |
|
|
|
60583855 |
Jun 29, 2004 |
|
|
|
Current U.S.
Class: |
604/95.01 ;
600/415 |
Current CPC
Class: |
A61B 5/06 20130101; A61B
5/062 20130101; A61B 5/061 20130101 |
Class at
Publication: |
604/095.01 ;
600/415 |
International
Class: |
A61M 31/00 20060101
A61M031/00; A61B 5/05 20060101 A61B005/05 |
Claims
1. A method of characterizing a surface in an operating region in a
subject's body using a magnetically navigable device, the method
comprising: navigating a magnetically navigable device by applying
a magnetic field to the device and changing the free length of the
device to bring the device into contact with a point on the
surface; recording the point by storing information representative
of the magnetic field applied to the device and the free length of
the device to cause the device to contact the surface at the point;
and repeating steps (a) and (b) for a plurality of points on the
surface.
2. The method according to claim 1 comprising using a computational
model of the device and the stored information representative of
the magnetic field applied to the device and the free length of the
device for each of the plurality of points to render the
surface.
3. The method according to claim 1 further comprising the step of
using a computational model of the magnetically navigable device
and the stored information representative of the magnetic field
applied to the magnetically navigable device to determine the
locations of the points, and displaying an image of the points.
4. A method of automatically characterizing a surface in an
operating region in a subject's body using a magnetically navigable
device, the method comprising: automatically navigating a
magnetically navigable device by applying a magnetic field to the
device to bring the device into contact with a plurality of points
in predetermined relation on the surface; and recording each point
by storing information representative of the magnetic field applied
to the device to cause it to contact the surface at the point.
5. The method according to claim 4 wherein the step of
automatically navigating includes adjusting the free length of the
medical device, and wherein the step of recording each point
includes the step of recording the free length of the magnetically
navigable device at each point.
6. The method according to claim 5 wherein the information
representative of the magnetic field applied to the magnetically
navigable device includes the magnetic field direction.
7. The method according to claim 5 wherein the magnetic field is
applied with at least one external source magnetic, and wherein
information representative of the magnetic field applied to the
magnetically navigable device includes the position of the at least
one magnet.
8. The method according to claim 5 wherein the magnetic field is
applied with at least one external source magnetic, and wherein
information representative of the magnetic field applied to the
magnetically navigable device includes the orientation of the at
least one magnet.
9. The method according to claim 5 wherein the magnetic field is
applied with at least one external source magnet, and wherein
information representative of the magnetic field applied to the
magnetically navigable device includes the position and orientation
of the at least one magnet.
10. The method according to claim 5 wherein the magnetic field is
applied with at least one electromagnet, and wherein information
representative of the magnetic field applied to the magnetically
navigable device includes the current supplied to the at least one
electromagnet.
11. A method of characterizing a surface in an operating region in
a subject's body using a remotely navigable device, the device
being responsive to at least one control variable to assume a
desired configuration, the method comprising: (a) navigating a
remotely navigable device by applying a control variable to the
device to bring the device into contact with a point on the
surface; (b) recording the point by storing information
representative of the at least one control variable applied to the
device to cause it to contact the surface at the point; and
repeating steps (a) and (b) for a plurality of points on the
surface.
12. The method according to claim 11 further comprising recording
the free length of the medical device responsive to the control
variable at each point.
13. The method according to claim 12 further comprising using a
computational model of the device to determine the location of each
point based upon the control variable being applied to the remotely
orientable medical device at a point and information representative
of the free length of the remotely orientable device at the point;
and displaying a plurality of the points to represent the
surface.
14. A method of automatically characterizing a surface in an
operating region in a subject's body using a remotely magnetically
navigable device, the medical device being responsive to at least
one control variable to assume a desired configuration, the method
comprising: automatically navigating a remotely navigable device by
applying at least one control variable to the device to bring the
device into contact with a plurality of points in predetermined
relation on the surface; recording each point by storing
information representative of the at least one control variable
applied to the device to cause it to contact the surface at the
point.
15. The method according to claim 14 wherein the step of
automatically navigating includes adjusting the free length of the
medical device, and wherein the step of recording each point
includes the step of recording the free length of the remotely
navigable device at each point.
16. The method according to claim 12 further comprising the step of
storing information representative of the free length of the
medical device when the device was at the selected point, and using
the stored information representative of the free length to change
the free length of the medical device to return the medical device
to the selected point.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
patent application Ser. No. 11/170,764, filed Jun. 29, 2005, which
claims the benefit of U.S. Provisional Application No. 60/583,855,
filed on Jun. 29, 2004. The disclosures of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates to the navigation of remotely
actuable medical devices in an operating region positioned in a
subject's body.
[0003] There are a number of instances in which it is desirable to
be able to determine the location of a medical device within an
operating region positioned in a subject's body to facilitate
navigation. Particularly in the accurate movement and positioning
of a medical device it is desirable to know the current location
and/or orientation of that device. Various localization systems
have been developed for this purpose, including magnetic
localization systems, which use electromagnetic signals transmitted
to or from the medical device to determine the location of the
medical device. An example of such a system is the CARTO.TM. XP EP
Navigation and Ablation System, available from Biosense-Webster
Inc. However, electromagnetic localization systems can be difficult
to use where there is moving metal in or near the operating region,
and can require extensive calibration. Other localization systems
have been developed using ultrasound, electric potential, or image
processing, however, these systems typically require that the
medical device be specially constructed or adapted for use with the
localization system.
SUMMARY OF THE INVENTION
[0004] The present invention relates to a method of navigating a
remotely actuable medical device in a subject's body. By using
information representative of at least one control variable of the
remote navigation system, and preferably also the operative length
of the medical device, the location of the medical device can be
determined. One possible way of determining the location of a
medical device is through the use of a computational model to
determine the location of the device at any point based upon the at
least one control variable and the operative length.
[0005] Various embodiments of the invention use the method of the
present invention to determine the current location of the medical
device, to return the medical device to a previous location; to
identify and/or display the path taken by the medical device; to
return to a path previously taken by the medical device; to
characterize a surface in the operating region in the subject;
and/or to create a map of a surface or a physiologic property on a
surface or within a volume. These and other features and advantages
will be in part apparent and in part pointed out hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a vertical cross-sectional view of a heart,
showing a catheter navigated to left atrium;
[0007] FIG. 2 is an enlarged view of the right atrium, showing the
catheter
[0008] FIG. 3 is a perspective view of the distal end of the
catheter, showing the catheter under the application of two
different magnetic fields, while the length remains constant;
[0009] FIG. 4 is an enlarged view of the left atrium, showing a
line of points;
[0010] FIG. 5 is a view of the distal end of a catheter of a
preferred embodiment of this invention;
[0011] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0012] The preferred embodiment of the present invention relates to
methods of navigating a remotely actuable medical device in the
body, and in the preferred embodiment for navigating a medical
device by determining the location of the distal tip of a remotely
navigable elongate medical device. In a preferred embodiment, the
remotely controllable elongate medical device is a magnetically
responsive medical device that orients with an applied magnetic
field. However this invention is not so limited, and applies to any
remotely navigable medical device that responds to one or more
applied control variables. Examples of such devices include medical
devices that employ mechanical, hydraulic, pneumatic,
electrostrictive/or magnetostrictive elements, or combinations
thereof, to control the configuration of at least a portion of the
device. The device may be any type of elongate medical device
including catheters, guidewires, and endoscopes. The operative
length of the device, i.e., the length of the device that can
respond to the control variables, is preferably automatically
controllable but could be manually controlled.
[0013] One embodiment of a method in accordance with the principles
of this invention is illustrated in FIG. 1, where the distal end of
a remotely navigable medical device, such as magnetically navigable
catheter 20, is shown in the left atrium LA of the a subject's
heart H. The distal end portion of the catheter 20 extends from the
distal end of a sheath 22. In this preferred embodiment, the
catheter 20 has at least one magnetically responsive element 24
adjacent its distal end. The element 24 may be a permanent magnetic
material (e.g., a neodymium-iron-born (Nd--Fe--B) alloy or other
suitable material) or it may be a permeable magnetic material
(e.g., hiperco). The element is preferably sized and shaped to
align the distal end of the catheter with an applied magnetic field
less than 0.1 T, and more preferably in an applied magnetic field
less than about 0.08 T. Thus, the distal end of the catheter 20 can
be aligned with a magnetic field applied to the operating region in
a subject, for example with one or more external source magnets.
The external source magnet can be one or more permanent magnets,
whose position and/or orientation can be changed to change the
magnetic field applied to the operating region. An example of a
suitable magnet system is disclosed in U.S. patent application Ser.
No. 10/056,227, filed Jan. 23, 2002 for Rotating and Pivoting
Magnet for Magnetic Navigation, incorporated herein by reference.
The external source magnet can also be one or more electromagnets
medical device, whose current can be changed to change the magnetic
field applied to the operating region. An example of a suitable
magnet system is disclosed in U.S. Pat. No. 6,241,671, issued Jun.
5, 2001, Open Field System for Magnetic Surgery, incorporated
herein by reference.
[0014] As shown in FIG. 1, the distal end of the catheter 20
extends through a sheath 22 and into the left atrium LA. A magnetic
field I.sub.1 is applied to the operating region, and the catheter
20 is extended to a length l.sub.1, and the distal end of the
catheter 20 contacts point p.sub.1. The magnetic field I.sub.1 has
at least a direction, but can also have a direction and a strength.
The length l.sub.1 is the free length of the device that can
respond to changes in the magnet field, which in most cases is the
length of the catheter 20 that projects beyond the distal end of
the sheath 22. The point p.sub.1 is uniquely identified by the
field I.sub.1 and the length l.sub.1. In accordance with the method
of this invention, the interface for controlling the magnetic field
and catheter length, preferably also includes a control for storing
some value representative of the magnetic field I.sub.1, and some
value representative of the catheter length l.sub.1, corresponding
to and uniquely identifying point P.sub.1.
[0015] The distal end of the sheath 22 functions as a base or flex
point for the catheter 20, so that the position and orientation of
the catheter base is known by suitable identification of the
sheath's distal end. If a sheath is not used, the catheter base is
determined by anatomical constraints as the most distal point of
support and can be identified from suitable image-based information
such as X-ray imaging. While the user can control the length of the
catheter manually or with an automated device, it is the free
length of the catheter 20, i.e. that portion of the catheter that
projects from the distal end of the sheath 22 and can respond to
the control variable (e.g. the applied magnetic field in the
preferred embodiment), that is important. Thus it is the control
variable(s) and the free length that define the configuration of
the device and, together with device base information, determine
the location of the distal end. If the position of the sheath does
not change, then the measure of the catheter length is a measure of
the free length.
[0016] As also shown in FIGS. 1 and 2, the magnetic navigation
system can be used to move the distal end of the catheter 20 to a
point p.sub.2 by applying a magnetic field I.sub.2 to the operating
region, and changing the length of the operating length to a length
l.sub.2. Again, in accordance with the method of this invention,
the interface for controlling the magnet field and catheter length
can include a control for storing some value representative of
magnetic field I.sub.2, and some value of the catheter length
l.sub.1, corresponding to and uniquely identifying point
P.sub.2.
[0017] The magnetic field I.sub.1 and the length l.sub.1 uniquely
identify the point p.sub.1 in the left atrium LA, and the magnetic
field I.sub.2 and the length l.sub.2, uniquely identify the point
p.sub.2 in the left atrium LA, as long as the points are within the
same chamber so that the device base is the same in each case.
Thus, these points have been localized (uniquely identified and
characterized) and this information can be used to automatically
return the medical device to one of the points p.sub.1 or p.sub.2
by applying the appropriate magnetic field and device length. These
points can also be used as part of a structure map of the surface
of the right atrium LA, and additional points can be collected to
provide a more detailed representation of the surface could
alternatively be positions (locations and/or orientations) of the
external permanent magnets. In the case of a magnetic navigation
system employing one or more external electromagnets, the
information could alternatively be the position and/or orientation
of the electromagnets, and/or the currents in the electromagnets.
Similarly, the information representative of the length can be the
actual length, or some other indication of the length, for example,
a position or sensor reading from an automatic device advancer. In
any case the information need only be sufficient to recreate the
condition so that that device can be returned to the point and/or
to provide inputs to a computational model of the device so that
the configuration of the device can be determined.
[0018] FIG. 3 illustrates the change in position achieved by a
change in magnetic field from a first field I.sub.1 to a second
field I.sub.2 while the length l of the device remains constant
(i.e., l.sub.1=l.sub.2).
[0019] In an alternative implementation of the preferred
embodiment, the magnetic medical device is navigable not by
changing the externally applied magnetic device, but by changing
the magnetic moment of the medical device in a static externally
applied field. In this implementation the control variable can be
one that controls or determines the magnetic moment of the medical
device, including for example currents supplied to electromagnetic
coils in the medical device, or any other control variables that
determine the configuration of the magnetically navigated medical
device. While the method has been described in the context of a
magnetically navigated medical device, using information
representative of the applied magnetic field and the length, this
method can also apply to mechanically navigated medical devices,
hydraulically navigated medical device, pneumatically controlled
medical devices, electrostrictive medical devices, magnetostrictive
medical devices.
[0020] In the case of mechanically navigated medical devices, the
control variables may be positions of one or more push wires or
pull wires, or positions of one or more gears for articulating the
medical device, or any other control variables that achieve the
configuration of the mechanically navigated medical device.
[0021] In the case of hydraulically navigated medical devices, the
control variables may be fluid pressures in one or more hydraulic
actuators, or chambers disposed in the medical device, or any other
control variables that determine the configuration of the
hydraulically navigated medical device.
[0022] In the case of pneumatically navigated medical devices, the
control variables may be gas pressures in one or more pneumatic
actuators or chambers disposed in the medical device, or any other
control variables that determine the configuration of the
pneumatically navigated medical device.
[0023] In the case of electrostrictive medical devices, the control
variables may be voltages or currents applied to one or more
electrostrictive elements or piezoelectric elements disposed in the
medical device, or any other control variables that determine the
configuration of the electrostrictive medical device.
[0024] In the case of magnetostrictive medical devices, the control
variables may be magnetic field strength and direction applied to
magnetostrictive elements in the medical device, or currents or
voltages applied to electromagnetic elements in the medical device,
or any other control variables that determine the configuration of
the magnetostrictive medical device.
[0025] As shown in FIG. 4, in accordance with another embodiment of
this invention, a device, such as catheter 20 can be magnetically
navigated along path P in the left atrium LA. Along the path P, the
catheter 20 passes a plurality of points p.sub.1 through p.sub.n.
At each point p.sub.x, information representative of the magnetic
field I.sub.x and the length l.sub.x is stored. The points
p.sub.1-p.sub.n can be selected by the user, or automatically
selected as the catheter 20 is moved. With the points p.sub.1
through p.sub.n stored, the entire path P or just a selected part
of the path P can be automatically renaviagted, the navigation
system using information about the field and length at each
successive point in the path to automatically move the catheter 20
along the path P.
[0026] To develop a map of a surface, the catheter 20 should
preferably contact the surface at each point with the same contact
force. The contact force can be measured for example with a sensor
on the distal tip of the catheter. The contact force can
alternatively be estimated by comparing an image of the actual
configuration of the catheter 20, with the predicted configuration
of the catheter using a computational model. The difference between
the actual and predicted configurations is indicative of the
contact force.
[0027] The information representing magnetic field and device
length can be used as an input to a computational model of the
medical device, i.e., a model that predicts the configuration of
the device based upon these inputs. The computational model can
then be used to generate a representation of the surface containing
the points. An example of such a computational model is disclosed
in U.S. patent application Ser. No. 10/448,273, filed May 29, 2003,
for Remote Control of Medical Devices Using a Virtual Device
Interface, incorporated herein by reference.
[0028] As shown in FIG. 5, a catheter 100, having a plurality of
strain gauges 102 thereon, is adapted for use with this methods of
this invention. Each strain gauge 102 has leads 104 and 106 so that
the local strain can be measured by measuring the change in voltage
across the strain gauge or the change in current through the strain
gauge. The catheter 100 is adapted to be configured by any means
described above, for example the catheter can include one or more
magnetically responsive elements, and can be configured by the
application of a magnetic field; alternatively the catheter can
include push wires, pull wires, gears, or other mechanical elements
for configuring the catheter; alternatively the catheter can
include electrostrictive (e.g. piezoelectric) or magnetostrictive
elements for configuring the catheter; or alternatively the
catheter can include fluid or gas chambers whose pressure can be
changed for configuring the catheter. However, the catheter 100 is
configured, the strain gauges measure the configuration, and thus
the measures from the strain gauges and the length of the device
uniquely define the configuration and the location of the distal
end based on a known location and orientation of the device base
within an anatomical chamber of interest. By storing the measures
of the strain gauges and the length, one can identify the present
location of the distal end of the catheter. Since measured strain
variables are derivatives of local displacements, suitable
integration of the measured strain values can yield local
displacements and thence the configuration of the device. This
information can be used to control whatever system is used to
configure the distal end of the device. Using a mathematical model
of the device, the control variables required by the particular
configuration system to achieve the stored measures from the strain
gauges can be determined and applied if desired. Alternatively, the
configuration can be repeated with a feed back system comparing the
current measures from the strain gauges with the stored measures
from the strain gauges. In one preferred embodiment, the strain
gauges are integrated with active elements, such as piezoelectric
elements, so that they both measure and cause the desired
configuration. A stored voltage or current not only identifies a
particular configuration, but can be used directly to recreate
it.
Operation
[0029] In one embodiment of the method of this invention, the
location of a magnetically orientable medical device at a point in
an operating region in a subject's body is determined by storing
information representative of the magnetic field being applied to
the medical device at the point. A computational model of the
medical device can be used to determine the location of the point,
with the stored information representative of the magnetic field
being applied to the medical device at the point as an input. The
information representative of the magnetic field applied to the
magnetically navigable device preferably includes the magnetic
field direction. Where the magnetic field is applied with at least
one external source magnetic, the information representative of the
magnetic field applied to the magnetically navigable device can
include the position of the at least one magnet, and/or the
orientation of the at least one magnet, and preferably both the
position and the orientation of the at least one magnet. Where the
magnetic field is applied with at least one electromagnet, the
information representative of the magnetic field applied to the
magnetically navigable device can include the current supplied to
the at least one electromagnet.
[0030] In another embodiment of the method of this invention, the
location of a magnetically orientable, mechanically advanceable
medical device at a point in an operating region in a subject's
body is determined by storing information representative of the
magnetic field being applied to the medical device at the point;
and storing information representative of the free length of the
medical device at the point. A computational model of the medical
device can be used to determine the location of the point, with the
stored information representative of the magnetic field being
applied to the medical device and the stored information
representative of the free length of the medical device as
inputs.
[0031] In another embodiment of the method of this invention, the
location of a magnetically navigable medical device at a point in
an operating region in a subject's body is determined by storing
information representative of the magnetic field being applied to
the magnetically responsive medical device at the point and storing
information about the free length of the medical device that can
flex in response to an applied magnetic field, at the point.
[0032] In another embodiment of the method of this invention, the
location of a medical device that has been navigated to a selected
point in an operating region in a subject by applying a magnetic
field to the medical device to orient the device, and mechanically
advancing the medical device, is determined by storing information
representative of the magnetic field being applied to the
magnetically responsive medical device at the point and storing
information about the free length of the magnetically navigable
medical device that can flex in response to an applied magnetic
field, at the point. The information representative of the magnetic
field applied to the magnetically navigable device preferably
includes the magnetic field direction. Where the magnetic field is
applied with at least one external source magnet, the information
representative of the magnetic field applied to the magnetically
navigable device can include the position of the at least one
magnet, and/or the orientation of the at least one magnet, and
preferably both the position and orientation of the at least one
magnet. Where the magnetic field is applied with at least one
electromagnet, the information representative of the magnetic field
applied to the magnetically navigable device can include the
current supplied to the at least one electromagnet.
[0033] In another embodiment of the method of this invention, at
least one location for a medical device in an operating region is
stored by recording some information relating to the magnetic field
applied to the medical device and some information relating to
length of the medical device when the medical device is in the
desired location. The information representative of the magnetic
field applied to the magnetically navigable device can include the
magnetic field direction. Where the magnetic field is applied with
at least one external source magnetic, the information
representative of the magnetic field applied to the magnetically
navigable device includes the orientation of the at least one
magnet, and/or the orientation of the at least one magnet, and
preferably both the position and the orientation of the at least
one magnet. Where the magnetic field is applied with at least one
electromagnet, the information representative of the magnetic field
applied to the magnetically navigable device can include the
current supplied to the at least one electromagnet.
[0034] In another embodiment of the method of this invention, a
surface in an operating region in a subject's body can be
characterized using a magnetically navigable device by (a)
navigating a magnetically navigable device by applying a magnetic
field to the device and changing the free length of the device to
bring the device into contact with a point on the surface; and (b)
recording the point by storing information representative of the
magnetic field applied to the device and the free length of the
device to cause the device to contact the surface at the point; and
repeating steps (a) and (b) for a plurality of points on the
surface. A computational model of the device can be used to
generate and render the surface, with the stored information
representative of the magnetic field applied to the device and the
free length of the device for each of the plurality of points as
inputs. More specifically, a computation model of the magnetically
navigable device and the stored information representative of the
magnetic field applied to the magnetically navigable device can be
used to determine the locations of the points, and displaying an
image of the points.
[0035] In another preferred embodiment of the method of this
invention, a method of displaying a structural map of a surface in
an operating region in a subject's body is displayed using a
magnetically orientable device by magnetically navigating the
medical device and mechanically advancing and retracting the
magnetically orientable device to a plurality of points on the
surface; storing information representative of the magnetic field
being applied to the magnetically orientable medical device at each
point; and storing information representative of the free length of
the magnetically orientable device at each point.
[0036] A computational model of the magnetically orientable device
can be used to determine the location of each point based upon of
the magnetic field being applied to the magnetically orientable
medical device at a point and information representative of the
free length of the magnetically orientable device at the point. A
plurality of the points can be displayed to represent the
surface.
[0037] In another embodiment of the method of this invention, a
physiological map of a portion of an operating region in a
subject's body can be made using a magnetically navigable device,
the method comprising: magnetically navigating the device to a
plurality of points in the operating region; storing information
representative of the magnetic field being applied to the
magnetically responsive device at each of the plurality of points;
storing information about the free length of the magnetically
navigable device at each of the plurality of points; measuring the
value of some physiological property at each of the plurality of
points. A plurality of these points and their respective
physiological properties can be displayed to display a
physiological map.
[0038] A computational model of the magnetically navigable device
can be used to determine the location of each of the points based
upon the stored information representative of the magnetic field
being applied at the point, and the free length of the device at
the point. The plurality of the points can then be displayed to
represent the surface of the surface, together with some indication
of the measured physiologic property at each point.
[0039] In another embodiment of the method of this invention, a
surface in an operating region in a subject's body is automatically
characterized using a magnetically navigable device by
automatically navigating a magnetically navigable device by
applying a magnetic field to the device to bring the device into
contact with a plurality of points in predetermined relation on the
surface and recording each point by storing information
representative of the magnetic field applied to the device to cause
it to contact the surface at the point. The step of automatically
navigating preferably also includes adjusting the free length of
the medical device, and wherein the step of recording each point
preferably includes the step of recording the free length of the
magnetically navigable device at each point. The information
representative of the magnetic field applied to the magnetically
navigable device preferably includes the magnetic field
direction.
[0040] Where the magnetic field is applied with at least one
external source magnet, the information representative of the
magnetic field applied to the magnetically navigable device can
include the position of the at least one magnet, and/or the
orientation of the at least one magnet, preferably both the
position and orientation of the at least one magnet. Where the
magnetic field is applied with at least one electromagnet, the
information representative of the magnetic field applied to the
magnetically navigable device can include the current supplied to
the at least one electromagnet.
[0041] In another embodiment of the method of this invention, a
magnetically navigable medical device is navigated to return to a
point to which the medical device had previously been magnetically
navigated by storing information representative of the magnetic
field applied to the medical device when the device was at a
selected point, and using the stored information representative of
the magnetic field to apply the same magnetic field to the medical
device to return the medical device to the selected point. The
method preferably further comprises storing information
representative of the free length of the medical device when the
device was at the selected point, and using the stored information
representative of the free length to change the free length of the
medical device to return the medical device to the selected point.
The information representative of the magnetic field applied to the
magnetically navigable device can include the magnetic field
direction.
[0042] Where the magnetic field is applied with at least one
external source magnet, the information representative of the
magnetic field applied to the magnetically navigable device can
include the position of the at least one magnet, and/or the
orientation of the at least one magnet, and preferably both the
position and orientation of the at least one magnet. Where the
magnetic field is applied with at least one electromagnet, the
information representative of the magnetic field applied to the
magnetically navigable device can include the current supplied to
the at least one electromagnet.
[0043] In another embodiment of the method of this invention, the
path through a volume in a subject's body taken by a magnetically
navigable medical device is recorded by applying a magnetic field
to the magnetically navigable medical device to navigate the
medical device along a path through the volume in the subject's
body; and, storing information representative of the magnetic field
applied to the medical device at each of a plurality of points
along the path. The method preferably further comprises adjusting
the length of the medical device to navigate the medical device
along the path through the volume in the subject's body and storing
information representative of the length of the medical device at
each of the plurality of points for which information about the
magnetic field is stored.
[0044] In another embodiment of the method of this invention, a
magnetically navigable medical device is navigated substantially
along a previously traversed path through a volume in a subject's
body by applying a magnetic field to the magnetically navigable
medical device to navigate the medical device along a path through
the volume in a subject's body; storing information representative
of the magnetic field applied to the medical device at each of a
plurality of points along the path and subsequently navigating the
magnetically navigable medical device substantially along the
previously traversed path by successively applying to the
magnetically navigable medical device, a magnetic field
corresponding to the magnetic field previously applied to the
medical device at the same point in the path. The method preferably
further comprises controlling the length of the medical device to
navigate the medical device along a path through the volume;
storing information about the length of the medical device at each
of the plurality of points at which information representative of
the magnetic field was stored; and wherein the step of subsequently
navigating the magnetically navigable medical device substantially
along the previously traversed path includes successively
controlling the length of the medical device to the length at the
same point in the path.
[0045] In another embodiment of the method of this invention, a
path through a volume in a subject's body taken by a magnetically
navigable medical device, is displayed by applying a magnetic field
to the magnetically navigable medical device to navigate the
medical device along a path through the volume in the subject's
body; storing information about the magnetic field applied to the
medical device at each of a plurality of points along the path;
determining the location of at least some of the plurality of
points using a computational model of the magnetically navigable
medical device and the stored information about the magnetic field
applied to each point; and displaying the path as a series of
points. The method preferably further comprises controlling the
length of the medical device to navigate the medical device along a
path through the volume; storing information about the length of
the medical device at each of the plurality of points at which
information representative of the magnetic field was stored; and
wherein the step of determining the location of at least some of
the plurality of points comprises using the computational model
with information representative of the length of the medical device
at each point.
[0046] In another embodiment of the method of this invention, the
location of a medical device at a point in an operating region in a
subject's body is determined. The medical device is responsive to
at least one control variable to assume a desired configuration,
and the location is determined by storing information
representative of the at least one control variable being applied
to the medical device at the point. The method preferably employs a
computational model of the medical device and the stored
information representative of the at least one control variable
being applied to the medical device at the point to determine the
location of the point.
[0047] In another embodiment of the method of this invention, the
location of a medical device in an operating region in a subject's
body is determined. The medical device is responsive to at least
one control variable to assume a desired configuration, and is
mechanically advanceable, and the location is determined by storing
information representative of the control variable being applied to
the medical device at the point; and storing information
representative of the free length of the medical device at the
point. A computational model of the medical device can be used to
determine the location of the point using the stored information
representative of the at least one control variable being applied
to the medical device and the stored information representative of
the free length of the medical device.
[0048] In another embodiment of the method of this invention, the
location of a medical device at a point in an operating region in a
subject's body is determined. The medical device is responsive to
at least one control variable to assume a desired configuration.
The location is determined by storing information representative of
the magnetic field being applied to the magnetically responsive
medical device at the point; and storing information about the free
length of the medical device that can flex in response to an
applied magnetic field, at the point.
[0049] In another embodiment of the method of this invention, the
location of a medical device that has been navigated to a selected
point in an operating region in a subject by applying a magnetic
field to the medical device to orient the device, and mechanically
advancing the medical device is determined by storing information
representative of the at least one control variable being applied
to the magnetically responsive medical device at the point; and
storing information about the free length of the medical device at
the point.
[0050] In another embodiment of the method of this invention, at
least one location for a medical device in an operating region, is
stored by recording some information relating to a control variable
applied to the medical device and some information relating to
length of the medical device when the medical device is in the
desired location.
[0051] In another embodiment of the method of this invention, a
surface in an operating region in a subject's body is characterized
using a remotely navigable device. The device is responsive to at
least one control variable to assume a desired configuration, and
the surface is characterized by (a) navigating a remotely navigable
device by applying a control variable to the device to bring the
device into contact with a point on the surface; (b) recording the
point by storing information representative of the at least one
control variable applied to the device to cause it to contact the
surface at the point; and repeating steps (a) and (b) for a
plurality of points on the surface. A computational model of the
remotely navigable device can be used to determine the location of
the point with the stored information representative of the control
variable applied to the remotely navigable device as an input. The
free length of the medical device is preferably also recorded at
each point.
[0052] In another embodiment of the method of this invention, a
structural map of a surface in an operating region in a subject's
body is displayed using a remotely orientable device. The device is
responsive to at least one control variable to assume a desired
configuration, and the surface is displayed by remotely orienting
the medical device and mechanically advancing and retracting the
remotely orientable device to a plurality of points on the surface;
storing information representative of the control variable being
applied to the remotely orientable medical device at each point;
and storing information representative of the free length of the
remotely orientable device at each point. A computational model of
the device is used to determine the location of each point based
upon of the control variable being applied to the remotely
orientable medical device at a point and information representative
of the free length of the remotely orientable device at the point.
The plurality of points are then displayed to represent the
surface.
[0053] In another embodiment of the method of this invention, a
physiological map of a portion of an operating region in a
subject's body is made using a remotely navigable device. The
medical device is responsive to at least one control variable to
assume a desired configuration, the map is made by applying the at
least one control variable to navigate the device to a plurality of
points in the operating region; storing information representative
of the control variable being applied to the remotely navigable
device at each of the plurality of points and storing information
about the free length of the remotely navigable device at each of
the plurality of points; measuring the value of some physiological
property at each of the plurality of points. A computational model
of the remotely navigable device can be used to determine the
location of each of the points based upon the stored information
representative of the at least one control variable being applied
at the point, and the free length of the device at the point.
[0054] In another embodiment of the method of the invention, a
surface in an operating region in a subject's body is automatically
characterized using a remotely magnetically navigable device. The
medical device is responsive to at least one control variable to
assume a desired configuration, and the surface is characterized by
automatically navigating a remotely navigable device by applying at
least one control variable to the device to bring the device into
contact with a plurality of points in predetermined relation on the
surface and recording each point by storing information
representative of the at least one control variable applied to the
device to cause it to contact the surface at the point.
Automatically navigating preferably includes adjusting the free
length of the medical device, and wherein the step of recording
each point preferably includes recording the free length of the
remotely navigable device at each point.
[0055] In another embodiment of the method of this invention, a
remotely navigable medical device is navigated to return to a point
to which the medical device had previously been navigated. The
medical device being responsive to at least one control variable to
assume a desired configuration, and the device is navigated by
storing information representative of the at least control variable
applied to the medical device when the device was at a selected
point, and using the stored information representative of the at
least control variable to apply the same at least one control
variable to the medical device to return the medical device to the
selected point. The method preferably also includes storing
information representative of the free length of the medical device
when the device was at the selected point, and using the stored
information representative of the free length to change the free
length of the medical device to return the medical device to the
selected point.
[0056] In another embodiment of the method of this invention, a
path through a volume in a subject's body taken by a remotely
navigable medical device is recorded by applying at least one
control variable to the remotely navigable medical device to
navigate the medical device along a path through the volume in the
subject's body; and, storing information representative of the at
least one control variable applied to the medical device at each of
a plurality of points along the path. The method preferably also
includes adjusting the length of the medical device to navigate the
medical device along the path through the volume in the subject's
body; storing information representative of the length of the
medical device at each of the plurality of points for which
information about the at least one control variable is stored.
[0057] In another embodiment of the method of this invention, a
remotely navigable medical device is navigated substantially along
a previously traversed path through a volume in a subject's body.
The medical device is responsive to at least one control variable
to assume a desired configuration, and is navigated by applying a
control variable to the remotely navigable medical device to
navigate the medical device along a path through the volume in a
subject's body and storing information representative of the at
least one control variable applied to the medical device at each of
a plurality of points along the path; subsequently navigating the
remotely navigable medical device substantially along the
previously traversed path by successively applying to the remotely
navigable medical device, at least one control variable
corresponding to the at least one control variable previously
applied to the medical device at the same point in the path. The
method preferably includes controlling the length of the medical
device to navigate the medical device along a path through the
volume; storing information about the length of the medical device
at each of the plurality of points at which information
representative of the at least one control variable was stored; and
successively controlling the length of the medical device to the
length at the same point in the path.
[0058] In another embodiment of the method of this invention, a
path through a volume in a subject's body taken by a remotely
navigable medical device is displayed. The medical device is
responsive to at least one control variable to assume a desired
configuration, and its path is displayed by applying at least one
control variable to the remotely navigable medical device to
navigate the medical device along a path through the volume in the
subject's body; storing information about the at least one control
variable applied to the medical device at each of a plurality of
points along the path; determining the location of at least some of
the plurality of points using a computational model of the remotely
navigable medical device and the stored information about the
magnetic field applied to each point; and displaying the path as a
series of points. The method preferably includes controlling the
length of the medical device to navigate the medical device along a
path through the volume; storing information about the length of
the medical device at each of the plurality of points at which
information representative of the at least one control variable was
stored; and using the computational model with information
representative of the length of the medical device at each
point.
* * * * *