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BACKGROUND OF THE INVENTION
This invention relates generally to Graphical User Interfaces (GUIs) and,
more particularly, to GUIs useful in connection with positioning,
orienting and operating a multiple electrode catheter within a patient's
body for diagnostic, therapeutic or other purposes.
Multiple electrode catheters, such as those shown and described in U.S.
Pat. Nos. 5,595,183 and 5,487,391 commonly owned by the assignee hereof,
are useful in a variety of medical diagnostic and therapeutic procedures.
Such catheters are particularly useful in diagnosing and treating certain
cardiac disorders, such as arrhythmias, that can occur for example when
localized areas of abnormal tissue within the heart disrupt the normal
sinus rhythm.
Today, physicians examine the propagation of electrical impulses in heart
tissue to locate aberrant conductive pathways. The techniques used to
analyze these pathways, commonly called "mapping," identify regions in the
heart tissue, called foci, which can be ablated to treat the arrhythmia.
One form of conventional cardiac tissue mapping techniques uses multiple
electrodes positioned in contact with epicardial heart tissue to obtain
multiple electrograms. The physician stimulates myocardial tissue by
introducing pacing signals and visually observes the morphologies of the
electrograms recorded during pacing. The physician visually compares the
patterns of paced electrograms to those previously recorded during an
arrhythmia episode to locate tissue regions appropriate for ablation.
These conventional mapping techniques require invasive open heart surgical
techniques to position the electrodes on the epicardial surface of the
heart.
Another form of conventional cardiac tissue mapping technique, called pace
mapping, uses a roving electrode in a heart chamber for pacing the heart
at various endocardial locations. In searching for the VT foci, the
physician must visually compare all paced electrocardiograms (recorded by
twelve lead body surface electrocardiograms (ECG's)) to those previously
recorded during an induced VT. The physician must constantly relocate the
roving electrode to a new location to systematically map the endocardium.
These techniques are complicated and time consuming. They require repeated
manipulation and movement of the pacing electrodes. At the same time, they
require the physician to visually assimilate and interpret the
electrocardiograms.
Multiple electrode catheters are effective in simplifying cardiac mapping
and ablation procedures. Such catheters make it possible to simultaneously
obtain data from several locations within the heart or other organ using a
single catheter. During such procedures, the multiple electrode catheter
is introduced into a chamber of the heart using known, minimally invasive
techniques. The catheter's progress through the vein and into the heart
can be followed on a fluoroscope. Radiopaque markers on the catheter
enhance the fluoroscopic visibility of the catheter. Once proper
deployment within the heart is verified by the fluoroscopic image,
localized electrical activity within the heart is monitored by means of
the individual electrodes. By noting particular types and patterns of
abnormality in the sensed waveforms, the physician is able to identify
areas of abnormality in the heart tissue. The abnormal tissues can then be
ablated or otherwise treated to remedy the condition.
Various advances in the catheter art now make it possible to include a
multitude of individual electrodes (e.g., sixty-four individual
electrodes) in a single diagnostic or mapping electrode. It is reasonable
to believe that further advances will enable still more electrodes to be
used. However, as more and more electrodes are added, it becomes more and
more difficult for the attending medical personnel to visualize and
interpret the additional data that are made available by such devices.
Maximum device effectiveness is realized when the attending medical
personnel are able quickly and accurately to visualize the catheter within
the body and interpret the information the device is providing. Along with
the greater resolution made possible by multiple electrode catheters comes
the need for simplified systems and methods of data interpretation.
In one prior data interpretation approach, the various waveforms acquired
by the individual electrodes are displayed on a screen. The medical
personnel need to mentally integrate the heart activity and position data
as displayed on the recorder and fluoroscopy screens in order to assess
the health of the underlying tissue. This approach requires a considerable
degree of skill and experience on the part of the attending medical
personnel. Furthermore, information regarding the relative location of an
ablation catheter with respect to the multiple electrodes is not readily
available. More significantly, the system becomes impractical and unwieldy
as the number of electrodes increases.
In another prior approach, information acquired from a number of sequential
locations of a roving electrode is digitally sampled and combined to
construct a model "surface" that is displayed on a screen and that
visually represents the tissue under consideration. Although much easier
to interpret than the prior approach that required mental integration of
various inputs, this system, too, provides an unrealistic representation
that requires skill and experience to use effectively. Furthermore, the
surface is difficult to generate as it requires that a roving electrode be
moved over the surface of the heart to reconstruct its geometry point by
point. To get reasonable accuracy, a high, sometimes impractical, number
of points is necessary.
As the number of electrodes, and, hence, the volume of raw data, increase,
it becomes more and more important to display data in a form that can be
readily interpreted and understood by the attending medical personnel.
Furthermore, it might be desirable to display information in such a way
that it can be easily related by the physician to information provided by
existing visualization or imaging systems, such as a fluoroscopic system.
Visually based systems, which enable such personnel to "see" what is
happening, offer a viable means of presenting large amounts of data in a
form that can be readily grasped and understood. Graphical user interfaces
are one means by which such a goal can be achieved.
SUMMARY OF THE INVENTION
The invention provides a graphical user interface for generating a visual
display depicting the relative position and orientation of a multiple
electrode catheter within a body. The graphical user interface includes a
display screen, an image generator for generating on the display screen an
image of the multiple electrode catheter, and a user-actuable control
coupled to the image generator for changing the relative position and
orientation of the image as displayed on the display screen.
It is an object of the invention to provide a new and improved apparatus
for facilitating the interpretation of data acquired through the use of
multiple electrode catheters.
It is a further object of the invention to provide a graphic user interface
that facilitates such interpretation.
It is a further object of the invention to provide a graphical user
interface that enables medical personnel to visualize a multiple electrode
catheter in place within a body.
It is a further object of the invention to provide a graphical user
interface that can display the location of roving electrodes with respect
to the multiple electrode catheter.
It is a further object of the invention to provide a graphical user
interface that can be readily implemented on existing computer apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present invention which are believed to be novel are
set forth with particularity in the appended claims. The invention,
together with the further objects and advantages thereof, may best be
understood by reference to the following description taken in conjunction
with the accompanying drawings, wherein like reference numerals identify
like elements, and wherein:
FIG. 1 is a simplified block diagram of a cardiac diagnostic and treatment
system having a multiple electrode catheter and a GUI embodying various
features of the invention.
FIG. 2 is a further simplified block diagram of the system shown in FIG. 1
further including a fluoroscope for monitoring the position of the
multiple electrode catheter within a patient's body.
FIG. 3 is a diagrammatic representation of a multiple electrode catheter
and a system of coordinates useful in describing positions relative to the
multiple electrode catheter.
FIG. 4(a) is a flowchart diagram useful in understanding an algorithm used
to rotate a wire-frame display of a multiple electrode structure using a
mouse.
FIG. 4(b) is a flowchart diagram useful in understanding the operation of
an algorithm used to identify user-requested electrodes within the
wire-frame display of the multiple electrode structure.
FIG. 4(c) is a flowchart diagram useful in understanding the operation of
an algorithm used to associate markers or anatomical features with the
wire-frame display of the multiple electrode structure.
FIG. 5 is a sample of a display screen generated by the GUI, useful in
understanding the look and feel thereof.
FIG. 6 is a sample of a display screen generated by the GUI showing a
multiple electrode structure within the right atrium of a heart for
purposes of diagnosing and treating atrial tachycardia within the right
atrium.
FIG. 7 is a sample of a display screen generated by the GUI showing a
multiple electrode structure within the left ventricle of a heart for
purposes of diagnosing and treating ventricular tachycardia within the
left ventricle.
FIG. 8 is a sample of a display screen generated by the GUI showing a
multiple electrode structure within the right atrium of a heart for
purposes of diagnosing and treating atrial flutter within the right
atrium.
FIG. 9 is a sample of a display screen generated by the GUI showing the
location of an ablation electrode during a tachycardia ablation procedure.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 and 2, a system 10 for diagnosing, treating or
otherwise administering health care to a patient 12 using a multielectrode
catheter 14 is shown. In the illustrated embodiment, the system 10
comprises a cardiac diagnostic system that can be used to diagnose and
treat abnormal cardiac conditions, such as arrhythmias. It will be
appreciated, however, that the system 10 is illustrative and that the
invention can be practiced in settings other than cardiac care.
As illustrated, the system 10 includes a multielectrode catheter 14
deployable within the heart of the patient 12. The catheter 14, which can
comprise a catheter of the type shown in co-pending application Ser. No.
08/587,251, filed Jan. 16, 1996, entitled Multiple Electrode Support
Structure and commonly owned by the assignee hereof, includes up to
sixty-four individual electrodes 16 disposed on a plurality of splines 18.
Each of the electrodes 16 is connected to an individual conductor in a
multiple conductor cable 20. The cable 20 terminates in one or more
connectors through which electrical connection can be made to the
individual conductors and, hence, to the individual electrodes.
The system 10 also includes a fluoroscope 22 (FIG. 2) of known construction
that can be used to monitor the position of the catheter 14 in the body.
The fluoroscope 22 includes a head 24 that generates and directs X-rays
into the body, a sensor and an image intensifier 26 that detects the
X-rays passing through the body, and a screen 28 that displays the
resulting images. The fluoroscope 22 can be rotated around the patient's
body to obtain views from different viewing points or "fluoro angles."
Certain fluoro angles are more frequently used in the field of
fluoroscopy. FIG. 3 illustrates the viewing angles for such views, with
respect to the coordinate system associated to the wire-frame
representation of the multiple electrode structure. These views are:
Right-Anterior-Oblique (RAO) 30 or 45, Anterior-Posterior (AP) and Left
Anterior-Oblique (LAO) 30 or 45. The AP View is provided when image
intensifier 26 is positioned perpendicular to the patient's chest. The LAO
view is provided when the image intensifier 26 is positioned over the left
side of the patient's chest. The RAO view is provided when the image
intensifier 26 is positioned over the right side of the patient's chest.
The angle with respect to the AP orientation is attached as a suffix to
the LAO or RAO nomenclature (e.g. if the angle is 30 degrees the view is
labeled RAO30 or LAO30). The GUI can also provide virtual views from
angles physically unrealized. For example, the Inferior view displays the
multiple electrode structure as seen by a viewer looking horizontally from
the patient's feet. The Superior view displays the multiple electrode
structure as seen by a viewer looking horizontally from the patient's
head. The Left or Right 90 views are views orthogonal to the main views
AP, RAO or LAO, depending on which view has been selected for display in
the left half-screen. For example, if the left half-screen displays a LAO
30 view, Right 90 would be the corresponding orthogonal view and
equivalent to RAO 60. Similarly, Left 90 would correspond to LAO 120,
although this angle is not physically realizable. Some fluoroscopes
include a pair of heads and sensors oriented at right angles to each
other. The simultaneous orthogonal views presented by such fluoroscopes
further assist the physician in following the progress of the catheter
into the patient's body.
The system 10 further includes a biological recorder 30 of known
construction that broadly functions to record, store, analyze and display
signals acquired by the electrodes 16 of the catheter 14. The biological
recorder 30 includes a recording/processing unit that records and
processes acquired signals and further includes a display unit that
displays the acquired signals to the attending health care personnel.
The system 10 further includes an interface 32 that enables information
acquired by the multiple electrodes to be loaded into the biological
recorder. To this end, the interface 32 functions broadly to couple
individual electrodes or groups of electrodes to the biological recorder.
By so coupling the electrodes, it is possible to route all the acquired
data into the biological recorder even though the number of available
inputs into the recorder may be less than the total number of electrodes.
The interface 32 also applies a known electrical field through the roving
electrode 19 and measures the potential distribution generated at the
electrodes 16. This information is then used to estimate the location of
the roving electrode. A system and method for determining the location of
electrode within body has been disclosed in co-pending application Ser.
No. 08/745,795 Filed Nov. 8, 1996 entitled "Systems and Methods for
Locating Guiding Operative Elements Within Interior Body Regions" and
application Ser. No. 08/679,156 filed Jul. 12, 1996 entitled "Systems and
Methods for Guiding Movable Electrode Elements within Multiple Electrode
Structures" and commonly owned by the assignee hereof. Other methods of
localizing electrodes could be employed by the skilled in the art such as
presented in prior art U.S. Pat. No. 5,558,091.
The interface 32 is also coupled to an external, user-actuatable,
microprocessor-based computer control such as a laptop computer 34 having
a keyboard 36 and display screen 38. Preferably, a mouse 39 is included
with the computer 34. The interface 32 operates under the command of the
computer 34 to interconnect individual electrodes 16 with individual
inputs to the biological recorder 30. The Interface 32 also communicates
back to the computer 34 information about the location of the roving
electrode 19. The computer 34, in turn, responds to requests and
instructions entered onto a keyboard 36 by the health care personnel and
commands the interface unit 32 to switch among the electrodes 16 as
required to achieve the desired function. Commands to configure/test the
unified switching system are issued by the computer 34 through the
keyboard 36.
A diagnostic and treatment system appropriate for use with the present
invention is shown and described, for example, in U.S. application Ser.
No. 08/770,971 entitled, "Unified Switching System for
Electrophysiological Stimulation and Signal Recording and Analysis," filed
Dec. 12, 1996 and commonly owned by the assignee hereof, the specification
of which is incorporated by reference herein.
The computer 34 receives roving electrode location information from the
interface 32 preferably via a serial bus such as RS 232. The location
information can comprise three numbers indicating the 3-D coordinates of
the roving electrode. Alternatively, it can be a data stream of 64 bits
with one bit corresponding to each of the 64 electrodes 16 of the multiple
electrode structure 14. A bit equal to logic 1 indicates that the
particular electrode 16 resides at less than a predefined distance
threshold (e.g. 2 mm) away from the roving electrode 19. A bit equal to
logic 0 indicates that the particular electrode 16 resides at more than
the predefined distance threshold away from the roving electrode 19. As
such, the approximate location of the roving electrode 19 can be retrieved
by knowing in the proximity of which of the electrodes 16 the roving
electrode resides.
The invention comprises a Graphical User Interface (GUI) that is
implemented on, and resident in, the computer 34. The GUI functions to
provide the attending medical personnel with a pictorial or graphic
representation of the multielectrode catheter 14 within the patient's
body. The various individual electrodes 16 and roving electrode 19 are
indicated, as are their locations and orientations relative to themselves.
The representation of the multielectrode catheter 14 and/or roving
electrode 19 may be manipulated on the display screen 38 until it suggests
the orientation of the catheter 14 within the patient's body 12. The
orientation may be guided and confirmed by comparing the appearance of the
representation of the catheter 14 to the appearance of the catheter on the
fluoroscope display 28. Such display helps "orient" the attending
personnel with respect to the catheter 14 and the patient's body 12 and
thus helps them interpret the data provided by the catheter 14.
The display of the position of the roving electrode 19 helps the physician
in guiding diagnosis or therapy application.
The invention makes use of the human ability to process information more
readily when presented in a graphic form than when presented as a series
of numerical data points. The graphic model of the multielectrode catheter
14 within the body 12 that the GUI provides enables the attending
personnel to visualize the locations of the individual electrodes 16 in
relation to actual tissue and thus helps the personnel interpret the data
obtained by each electrode 16. The GUI further enables the personnel to
"turn" their point of view relative to the catheter 14 and the patient 12
and thus "see" the catheter 14 from positions that are not physically
realizable. The GUI also enables the personnel to label various electrodes
16, enter notes onto the display 38 and otherwise add visual or
informational prompts or cues that further aid in interpreting the
information provided by the catheter 14.
The GUI provides a graphical model that represents how a catheter 14 would
be situated relative to various anatomical structures if certain
assumptions concerning the catheters' location are correct. By reference
to this model, the attending personnel are able to visualize were each
electrode 16 and spline 18 is located within the patient's body 12.
During a diagnostic or other medical procedure, the fluoroscope 22 is used
to monitor the position of the catheter 14. The GUI provides a simplified
and idealized representation that supplements the fluoroscopic image 28.
When placed into operation, the GUI displays a simplified, idealized
graphical image of the particular type of multielectrode catheter 14 being
used in the procedure. In the illustrated and preferred embodiment, the
GUI provides a split screen image having a left panel 40 and a right panel
42. A wire-frame image 44 of the catheter 14 appears in standard
orientations on both the right and left panels. The particular GUI shown
and described is intended for use with a single type of multielectrode
catheter 14 of the type shown and described in U.S. Pat. No. 5,549,108
issued Aug. 27, 1996 entitled "Cardiac Mapping and Ablation Systems" and
U.S. Pat. No. 5,509,419 issued Apr. 23, 1996 entitled "Cardiac Mapping and
Ablation Systems" and commonly owned by the assignee hereof. Accordingly,
information regarding the catheter is already retained within the GUI.
Alternatively, in other embodiments, the system operators can enter the
type of catheter that is being used. The GUI can then display the type of
catheter thus selected.
After the initial form of the catheter 14 is displayed, it is necessary
next, to set the view in the left panel 40 to match the view of the
fluoroscope 28. To this end, the attending personnel compares the
fluoroscopic image 28 of the catheter 14 and then manipulates the GUI
image 44 on the left panel 40 so that the catheter 44 shown thereon
closely matches the live view as seen on the fluoroscopic display 28. To
accomplish this, the GUI includes a plurality of on-screen buttons 46
(FIG. 3) that can be pressed to cause the catheter image 44 to rotate.
These buttons are the X, Y and Z orientation buttons. These buttons are
used to change the relative position of the multiple electrode catheter
orientation from its initial position. Thus, the system operator moves the
cursor to one of the orientation buttons and presses the left mouse
button. This action causes the catheter image 44 to rotate about an
idealized coordinate axis 48 located at the virtual multiple electrode
catheter center shown in FIG. 3. As to be expected, the X orientation
button rotates the multiple electrode catheter image 44 in either a
left-to-right or right-to-left direction, the Y orientation button rotates
the multiple electrode catheter image in either a top-to-bottom or
bottom-to-top direction and the Z orientation button rotates the multiple
electrode catheter image in either a clockwise or counterclockwise
direction.
Assume a point P.sub.0 of coordinates x.sub.0, y.sub.0, z.sub.0 on the
envelope surface of the structure 14. After a rotation of angle .alpha.
about the X axis the new position of P(x, y, z) is given by equation (1).
##EQU1##
Equation (2) and (3) define rotations of angle .alpha. about the Y and Z
axis, respectively:
##EQU2##
In general, if a sequence of X, Y, or Z rotations is performed, the final
coordinates of the point P depend on the exact order the rotations are
performed in.
Alternatively, the system operator may utilize the mouse controls to rotate
the multiple electrode catheter image. Whenever the cursor is positioned
in the left panel 40 and the left mouse button is pressed, the cursor
changes from an arrow-style image to that of a hand-style image 50. This
action causes the movement, that is to say, the rotation of the multiple
electrode catheter image in response to the movement of the mouse by the
system operator. By keeping the mouse left button pressed, the system
operator may position the multiple electrode catheter image. When the left
mouse button is released, the multiple electrode catheter image 44 remains
in the current orientation. FIG. 4(a) presents the flowchart of the
algorithm for the mouse-driven rotation. Element 100 draws the hand icon
when the mouse button is pressed. Element 102 computes the direction of
mouse movement. Based on this information, element 104 computes two
rotation angles about the X and Y axes. Element 106 performs the actual
rotation based on equations (1) and (2) above. The action of rotating the
wire-frame multiple electrode catheter representation 44 in the left panel
40 by means of X, Y and Z orientation button or mouse movement may be
repeated until the system operator is satisfied with the orientation of
the multiple electrode catheter image in reference to the fluoroscopic
image 28.
Preferably, the wire-frame representation 44 of the multiple electrode
catheter 14 shows a plurality of splines 52 corresponding in number to the
actual number of splines 18 used in the multielectrode catheter 14 and
further shows a plurality of electrodes 54 on each spline 52 corresponding
in number to the actual number of electrodes 16 on each spline 18. In the
preferred embodiment, splines 52 and electrodes 54 on the wire-frame image
44 are highlighted, colored differently, sized distinctly or otherwise
distinguished visually from the others to provide a representation of the
multiple electrode catheter in a virtual three-dimensional space where the
center of the wire-frame model 44 is designated as the center of that
three-dimensional space. In the illustrated embodiment, the wire-frame
image 44 is generated such that splines 52 and electrodes 54 which lie in
the background of the three-dimensional space (i.e., behind the center of
the three-dimensional space as viewed from the system operator's viewing
angle) appear darker or shadowed compared to the splines 52 and electrodes
54 appearing in the foreground. This enhances the three-dimensional
appearance of the multiple electrode catheter image 44 on the screen 38.
Once the orientation of the virtual multiple electrode catheter image is
matched to the real fluoroscopic image, as viewed by the system operator,
it may be saved or stored in the computer memory by pressing the "Save
View" button. The "Save View" button provides for the system operator to
save or store the current multiple electrode catheter image as any of the
standard views, i.e., the "AP", "LAO45", "LAO30", "RAO30" OR "RAO45"
views.
To further assist the operating personnel in interpreting what they see, it
is frequently helpful to provide other viewing angles that are related to
the standard fluoroscopic view but not realizable by such equipment. To
this end, the GUI based on the properly orientated image shown in the left
panel of the display, is operable to generate and display multiple
electrode catheter images in the right panel that are orthogonal to the
view in the left panel. Such orthogonal views are displayed in the right
panel relative to the view set in the left panel.
In the illustrated embodiment, the GUI provides orthogonal views calculated
from the "Superior", "Inferior", "Left 90" and "Right 90" views.
Preferably, the wire-frame representation 44 of the multiple electrode
catheter 14 shows a plurality of splines 52 corresponding in number to the
actual number of splines 18 used in the multielectrode catheter 14 and
further shows a plurality of electrodes 54 on each spline 52 corresponding
in number to the actual number of electrodes 16 on each spline 18.
Preferably, one or more of the splines 52 or electrodes 54 is highlighted
or otherwise distinguished visually from the others to provide a reference
for orienting the displayed wire-frame image 44. In the actual catheter
14, one or more of the splines 18 or electrodes 16 are provided with a
fluoroscopic marker that appears on the fluoroscope screen 28 and that
serves to identify a particular one of the electrodes 16 for reference
purposes. The electrode 60 highlighted by the GUI corresponds to this
electrode and is positioned to closely match the position of the
corresponding electrode on the fluoroscope screen 28.
The described procedure thus coordinates the "three dimensional" wire-frame
multiple electrode catheter representation 44 generated and displayed by
the GUI with the two dimensional display of the actual multiple electrode
catheter 14 shown on the fluoroscope screen 28.
After the displayed multiple electrode catheter image 44 is properly
oriented, the view can be saved by clicking the "Save View" and "OK"
buttons that appear on the display screen 38.
In the illustrated embodiment, the wire-frame image 44 generated on the
left panel 40 of the display 38 corresponds to the view of the multiple
electrode catheter 14 displayed on the fluoroscope screen 28. To further
assist the operating personnel in interpreting what they see, it is
frequently helpful to provide other views that are not easily realizable
using the fluoroscopic equipment 22. To this end, the GUI, based on the
properly oriented image 44 shown on the left panel 40 of the display 38,
is operable to generate and display images 44' of how the multiple
electrode catheter image 44 would appear if view from other angles. Such
alternate views are displayed on the right panel 42 of the display 38.
In the illustrated embodiment, the GUI provides "Superior," "Inferior,"
"Left 90.degree." and "Right 90.degree." views. These views are obtained
by clicking the appropriately labeled corresponding buttons on the screen
38. The image appearing on the right panel 42 of the display 38 tracks the
orientation of the image 44 on the left panel 40. Thus, if the image
orientation on the left display panel 40 is changed or adjusted, the right
image 44' will also change to reflect the new orientation of the catheter
14 relative to the body.
In the illustrated embodiment, fluoro angles between -90.degree. and
+90.degree. can be used and can be entered into the GUI. Thus, the GUI can
be still be effectively used if, for some reason, the attending personnel
elect to position the fluoroscope to a non-standard fluoro angle. In the
illustrated embodiment, views at the standard fluoro angles of
-45.degree., -30.degree., 0.degree., +30.degree. and +45.degree. can be
automatically saved. Customized views at non-standard fluoro angles can
also be named and saved.
As previously mentioned, the primary function of the GUI is to provide a
visual image or model 44 that assists the operating personnel in
visualizing the multiple electrode catheter 14 within the patient's body
12 and interpreting the data acquired from the multiple electrode catheter
14. Although this is largely achieved by orienting the wire-frame display
representation of the electrode basket to match the actual image provided
by the fluoroscope, the GUI provides several additional functions that
further enhance its effectiveness. Various of these additional functions
are described below.
A MARKERS function is provided which enables the operator to alter and
enhance the displayed multiple electrode catheter wire frame image. The
MARKERS function includes an ADD MARKER function that enables the operator
to add an identifier or marker to selected locations of the electrode
image 44 displayed in the left screen 40. This function is useful if the
operator wishes to mark selected locations that are significant or of
interest, such as mapping sites, ablation sites, etc. By having such sites
highlighted or otherwise distinguished, the operator is better able to
remain coordinated and oriented with the displayed image and, therefore,
better able to interpret data recovered by the multiple electrode
structure. The markers appear on the surface defined by the various
splines 52.
The MARKERS function is used by clicking the ADD MARKER button that appears
on the screen after the general "MARKERS" button is clicked. Pressing the
right mouse button on an electrode causes a marker to appear on the
screen. With the right button thus depressed, the mouse is used to "drag"
the marker over the implied surface of the multiple electrode catheter to
the desired location. When the right button is released, the marker is
"dropped" into the desired marker location. Markers can thus be placed
near electrodes on either the foreground or background of the multiple
electrode catheter. FIG. 4(b) shows the flowchart of the algorithm used to
add markers. Element 200 assigns the initial x.sub.0, y.sub.0, z.sub.0
coordinates of the marker when the mouse button is pressed. These initial
coordinates are identical to those of the electrode 16 acting as origin of
the placement. Element 202 generates the marker symbol and inserts the
corresponding software data structure into a linked list. Element 204
computes the direction of the mouse movement based on information received
from the mouse port. Element 206 converts the direction information into
two rotation angles, about the X and Y axes, respectively. Element 208
computes the new location of the marker based on equations (1) and (2).
Element 210 assigns the final x, y, z coordinates to the marker when the
mouse button is released. Markers are created as data structures
comprising: pointer to previous marker, order number, coordinates,
comments, time stamp and pointer to next marker.
Also included in the MARKERS function is a COMMENT function that enables
the operator to add custom notes or comments to each marker. For example,
if the operator wishes to comment on the significance of each selected,
marked site, the COMMENT function can be used for this purpose. A COMMENT
window appears as soon as the marker is "dropped" at the selected site. A
time stamp is preferably included in the comment. The operator can enter
the desired comment into the comment window using the computer keyboard.
By clicking the OK button, the comment thus entered is saved. If no
comment is desired, the CANCEL button can be clicked. A PREV. COMMENT
button is provided which, when actuated, displays comments previously
entered with earlier markers. A NEXT COMMENT button displays comments
associated with later entered markers. Once a marker is "dropped," its
comments can be retrieved by placing the cursor onto the marker and
pressing the right mouse button.
A DELETE MARKER function is p | | |
