Patent Application
20090076476
The invention relates generally to minimally-invasive instruments and systems, such as manually or robotically steerable catheter instrument systems, and more particularly to systems and methods for sensing, mapping and displaying intra-body tissue compliance.
Standard surgical procedures typically involve using a scalpel to create an opening of sufficient size to enable a surgical team to gain access to an area in the body of a patient for the surgical team to diagnose and treat one or more target sites. When possible, minimally invasive surgical procedures may be used instead of standard surgical procedures to minimize physical trauma to the patient and reduce recovery time for the patient to recuperate from the surgical procedures. Minimally invasive surgical procedures typically require using extension tools (e.g., catheters, etc.) to approach and address the target site through natural pathways (e.g., blood vessels, gastrointestinal tract, etc.) from a remote location either through one or more natural body orifices or percutaneous incisions. As can be appreciated, the surgeon may have limited feedback (e.g., visual, tactile, etc.) to accurately navigate the extension tools, such as one or more catheters, and place the working portions of the extension tools at precise locations to perform the necessary diagnostic and/or interventional procedures. As such, standard surgical procedures might be chosen for the patient even though minimally invasive surgical procedures may be more effective and beneficial for treating the patient.
For example, many conventional minimally-invasive cardiac diagnostic and/or interventional techniques involve accessing the right atrium of the heart percutaneously with a catheter or catheter system (whether manual or robotically controlled) by way of the inferior vena cava. When manually controlling an elongate instrument, such as a catheter, in any one of these applications, the physician operator can push on the proximal end of the catheter and attempt to feel the distal end make contact with pertinent tissue structures, such as the walls of the heart. Some experienced physicians attempt to determine or gauge the approximate force being applied to the distal end of a catheter due to contact with tissue structures or other objects, such as other instruments, prostheses, or the like, by interpreting the loads they tactically sense at the proximal end of the inserted catheter with their fingers and/or hands. Such an estimation of the force, however, is quite challenging and imprecise given the generally compliant nature of many minimally-invasive instruments, associated frictional loads, dynamic positioning of the instrument versus nearby tissue structures, and other factors.
Accordingly, there is a need to develop systems and methods that would facilitate more accurate navigation of extension tools and more precise placement of tools and instruments at target sites for performing diagnostic and/or interventional procedures in minimally invasive operations.
Embodiments of the present invention are directed to the use of a robotically-controlled medical instrument system for generating a geometric mapping of an area of internal body tissue (e.g., the wall of a heart chamber), which depicts or is otherwise is correlated to tissue compliance, or a characteristic related to the tissue compliance. In various embodiments, a graphic image or model of the area of body tissue can be generated and/or displayed, with regions of the area differentiated based upon the measured tissue compliance or a characteristic of the tissue that is determined based upon the measured tissue compliance. By way of non-limiting example, the tissue compliance may be used to determine tissue type, such as bone, soft tissue, myocardial wall, etc. In one embodiment, a graphically rendered image of the map depicts a geometric map of the tissue area (e.g., a chamber of the heart), with corresponding respective tissue types displayed in a different color, shade, or other demarcation as determined from their respective compliance.
In one embodiment, a robotically-controlled medical instrument system includes an elongate flexible guide instrument coupled to an instrument driver. The guide instrument defines a working lumen or channel through which an electrophysiology (e.g., mapping and/or ablation) catheter may be positioned through a proximal end opening of the guide instrument in communication with the working lumen. The catheter is inserted through the length of the guide instrument lumen, until a distal end of the catheter extends out of a distal opening of the guide instrument in communication with the lumen. The guide instrument is inserted into a patient's body (the catheter may be inserted into the guide instrument before or after it has been inserted into the body), with a bendable distal end portion of the guide instrument positioned in a selected anatomical workspace to be mapped (or for which a wall portion or other tissue structure is to be mapped). The distal end portion of the guide instrument is maneuvered within the workspace, so that the distal end of the catheter periodically contacting a tissue structure or surface within or bordering the workspace. A force sensor or sensing apparatus associated with the distal end portion of the catheter, e.g., embedded in the distal tip, or coupled to a proximal end of the catheter (i.e., proximal of the guide instrument), senses a force (or “load”) met by the catheter when it comes into contact with the tissue wall or structure. In alternate embodiments, the force sensor may take on numerous different configurations and can be positioned at various locations along the catheter (e.g., built into the tip, or a strain gage provided in a wall of the catheter), such as a load sensor, pressure sensor or other suitable sensor located at or near the distal end of the guide catheter. The force sensor generates force signals responsive to the force applied to the distal end of the guide catheter when it contacts a tissue surface.
The instrument system further includes or is otherwise operatively coupled with a localization (or “position determining”) system for determining the relative position of the distal end of the catheter as it contacts a tissue surface or structure. The position determining system generates position signals which are responsive to the position of the catheter as it is moved to a plurality of locations on an area of body tissue. The position determining system may be any suitable system, including without limitation, localization systems such as those which use magnetic sensors and antenna, open loop or closed loop position systems, shape sensing system such as Bragg fiber optic systems, etc.
The position determining system and force sensor are operatively coupled to a suitable processor (e.g., a system controller or associated computer), a well as associated signal conditioning electronics (collectively, “computer assembly”), with is preferably coupled to a graphic display. The computer assembly is configured to receive and process the position data to generate a geometric map of a tissue surface or other structure based on the localization data provided by the position determining system. The computer assembly is also configured to receive and process the force signals and to calculate a relative compliance of the tissue being contacted by the distal end of the catheter at each of the contact locations. The computer assembly can then generate and display a geometric map correlated with the tissue compliance of the tissue at various regions of the area of tissue of interest.
A method of mapping an area of body tissue using the robotic instrument system is described herein. The guide instrument is introduced into a patient's body. Then, the distal end of the guide catheter is robotically maneuvered into contact with a plurality of locations on an area of body tissue at an interventional procedure site. The robotic instrument system may maneuver the distal end to the plurality of locations in an automated manner (e.g., moving around the heart chamber or other anatomical space and automatically collecting position data and tissue compliance data needed to render a map). For example, a robotic catheter configured with a force sensor may be utilized to palpate and map the interior wall of a uterus or kidney. Alternatively, a physician may drive the catheter by giving commands to the robotic instrument system to go to a particular location, and then to move the distal end of the guide catheter into contact with a plurality of locations on the body tissue. This may be with an organ such as the patient's heart or kidney, or other body lumen such as an artery, or any other body structure. As the distal end of the catheter is moved in to contact with each location on the body tissue, the force on the tip and the deflection of the tissue due to the force is sensed by the system in order to determine the tissue compliance of the tissue at each location. At substantially the same time, the position of each of the locations on the body tissue is also determined. This data is then used to generate a geometric map of the body tissue which is representative of the tissue compliance of the tissue.
Further, the tissue compliance may be used to determine other tissue characteristics such as the type of tissue, condition of the tissue, or other characteristic. For example, one region of the tissue may be very elastic or squishy which may be indicative of soft tissue, while another region may be more firm, indicative of muscle tissue or bone. The method may also be used to identify tissue abnormalities in particular being mapped. For example, a calcified of cancerous tissue can be much harder and less compliant than normal, healthy tissue surrounding it. Then, the generated map can show a graphic image of the area of body tissue with the regions of different tissue characteristics demarcated, such as being shown in different shades, colors, cross-hatching, labels or other suitable graphic indication. The map may then be used in planning and performing a surgical procedure (including diagnosis and treatment procedures), with the same robotic instrument system or other surgical instruments.
Thus, in one embodiment, a medical instrument system (e.g., a robotic instrument system) includes a controller, an instrument driver in communication with the controller, and an elongate instrument coupled to the instrument driver, the instrument driver configured to manipulate a distal end portion of the instrument in response to control signals generated by the controller. A force sensor is associated with the instrument and generates force signals responsive to a force applied to the distal end portion of the instrument. The force sensor may be coupled to the distal end portion of the instrument, or at some other location, and may be a unidirectional force sensor that senses force applied substantially normal to a longitudinal axis of the instrument, or a multi-directional force sensor. A position determining system is also associated with the instrument, and generates position data indicative of a position of the distal end portion of the instrument. The system includes a processor operatively coupled to the force sensor and position determining system, the processor configured to process the respective force signals and position data to generate a geometric rendering of an internal body tissue surface based at least in part upon sensed forces applied to the distal end of the instrument as it is maneuvered within an interior region of a body containing the body surface.
By way of non-limiting examples, the processor may be configured to determine a characteristic of tissue (e.g., tissue stiffness or compliance) at a location on the tissue surface based on a sensed force applied to the distal end portion of the instrument as the instrument is maneuvered against the tissue surface at the respective location. A display is preferably coupled to the processor for displaying the geometric rendering of an internal body tissue surface, for example, wherein regions of the body tissue area in the map having differences in tissue compliance are visually highlighted. In one such embodiment, the graphic rendering of the tissue surface is generated by identifying a plurality of determined positions of the instrument distal end portion within the interior body region at which a substantially same amount of applied force is detected. In another such embodiment, the graphic rendering of the tissue surface includes a first tissue surface boundary determined based upon a first plurality of locations within the interior body region at which a first substantially same amount of force is detected on the distal end portion of the instrument, and a second tissue surface boundary determined based upon a second plurality of locations within the interior body region at which a second substantially same amount of force greater than the first amount is detected on the distal end portion of the instrument. In this embodiment, the processor may be configured to determine a characteristic of an area of tissue in the tissue surface based on a relative spacing between the first and second surface boundaries.
In one embodiment, a working instrument, such as a mapping and/or ablation catheter, is carried by a robotically-driven guide instrument, wherein the force sensor is configured to generate force signals responsive to a force applied to a distal end portion of the working instrument, and the position determining system generates position data indicative of a position of the distal end portion of the working instrument. In this embodiment, the processor generates and displays (or causes to be displayed) a geometric rendering of an internal body tissue surface based at least in part upon sensed forces applied to the distal end of the working instrument while it is extended out of a distal opening of the guide instrument and maneuvered by the guide instrument within an interior region of a body containing the body surface. By way of non-limiting example, the distal tip portion of the working instrument may be extended out of the distal opening of the guide instrument by one or both of retraction of the guide instrument relative to the working instrument and extension of the working instrument relative to the guide instrument. By way of another non-limiting example, the force sensor may be coupled to a proximal portion of the working instrument that extends proximally out of the guide instrument.
In one embodiment, a method of mapping an area of body tissue includes the acts of maneuvering a distal end portion of an elongate instrument within an interior body region; determining a position of the instrument distal end portion within the body region; and sensing a force applied to the instrument distal end portion at the determined position. These acts are repeated for a multiplicity of determined positions of, and sensed forces applied to, the instrument distal end portion within the interior body region, and the respective determined positions and sensed forces for the multiplicity of determined positions are then processed to generate and display a geometric rendering of an internal body tissue surface located within the interior body region, in particular, based on correlating the sensed forces with those corresponding to contacting a tissue surface.
By way of non-limiting example, processing of the respective determined positions and sensed forces to generate and display a geometric rendering of the internal body tissue surface may comprise identifying a plurality of determined positions of the instrument distal end portion within the interior body region at which a substantially same amount of applied force is detected. In one such embodiment, the geometric rendering of the internal body tissue surface includes a first tissue surface boundary determined based upon a first plurality of locations within the interior body region at which a first substantially same amount of force is detected on the instrument distal end portion, and a second tissue surface boundary generated based upon a second plurality of locations within the interior body region at which a second substantially same amount of force greater than the first amount is detected on the instrument distal end portion. In such an embodiment, a characteristic of an area of tissue in the tissue surface may be determined based on a relative spacing between the first and second surface boundaries.
In one such embodiment, a representation of the interior body region is displayed to facilitate initial positioning of the instrument distal end within the region under the control of the operator prior to obtaining of the multiplicity of determined positions.
In one such embodiment, the controller causes the instrument distal end to be maneuvered along a determined set of trajectories based on physical characteristics of the interior body region, e.g., a heart chamber, an anatomical workspace at least partially surrounding an organ exterior surface, an interior of an organ, or an interior of the gastro-intestinal tract, by way of non-limiting examples.
Methods according to such embodiments may further include determining a characteristic (e.g., relative stiffness or compliance, or a surface tension) of an area of tissue on the tissue surface based on a sensed force or forces applied to the instrument distal end portion as it is maneuvered against the tissue surface area. Such methods may also further include identifying a tissue anomaly in the tissue surface based on a sensed force or forces applied to the instrument distal end portion as it is maneuvered against the tissue surface, wherein approximate boundaries of the tissue anomaly on the tissue surface may be displayed for operator review, diagnosis and/or treatment planning.
In accordance with a further aspect of the disclosed inventions, a medical instrument system includes a controller having a user interface for receiving operator input commands; an instrument driver in communication with the controller; and an elongate instrument coupled to the instrument driver, the instrument driver configured to manipulate a distal end portion of the instrument in response to control signals generated by the controller at least partially in response to received operator commands. A force sensor is associated with the instrument, wherein the force sensor generates force signals responsive to a force applied to the distal end portion of the instrument. A processor is operatively coupled to the force sensor and controller, and configured to process the respective force signals to generate applied force data based at least in part upon sensed forces applied to the distal end of the instrument. A display is coupled to the processor for displaying the applied force data. In one such embodiment, the operator commands include an applied force limit on the instrument.
Methods employing this aspect of the disclosed inventions include a method of diagnosing and/or treating internal body tissue by maneuvering a distal end portion of an elongate instrument against an internal body tissue surface until either (i) sensing that a threshold level of force is being applied by the instrument distal end against the tissue surface, or (ii) the instrument distal end is extended to or beyond a determined movement limitation. Such methods may be carried out using a robotic instrument coupled to an instrument driver configured to manipulate the instrument distal end portion in response to control signals generated by a controller, wherein the control signals being generated at least in part in response to operator commands received through a user interface coupled to the controller.
In one such embodiment, the user interface includes a haptic input device, wherein the controller transmits signals to the input device to cause the input device to impart a detectable resistance to movement of the input device corresponding to an actual amount of force being applied against the instrument distal end portion by the tissue surface. Upon sensing that the threshold level of force is being applied by the instrument distal end against the tissue surface, the controller transmits a workspace limitation signal to the input device causing the input device to prevent movement of the input device in a manner that would cause a corresponding movement of the instrument distal end against the tissue surface and further increase the amount of applied force.
If for some reason the instrument distal end is extended to or beyond the determined movement limitation prior to reaching the threshold force level, the controller at least partially disables the user interface to prevent additional extension of the instrument distal end portion. A graphical representation of the instrument distal end and tissue surface may be displayed in conjunction with the procedure, wherein movement of the instrument distal end relative to the body surface is shown substantially in real time, including a representation of an actual sensed force applied by the instrument distal end against the body surface. By way of example, the graphical representation of the instrument distal end may change in color based on a corresponding change or changes in the actual sensed force applied by the instrument distal end against the body surface.
In accordance with yet another embodiment, a medical instrument system includes an elongate instrument, and a controller configured to selectively actuate one or more motors operatively coupled to the instrument to thereby selectively move the instrument. A force sensor associated with the instrument generates force signals responsive to a force applied to the distal end portion of the instrument, and a processor operatively coupled to the force sensor and controller processes the respective force signals to generate applied force data based at least in part upon sensed forces applied to the distal end of the instrument. The system further includes a haptic input device in communication with the controller and configured for generating instrument motion commands in response to a directional movement of the input device, wherein the controller transmits signals to the input device to cause the input device to impart a detectable resistance to movement of the input device corresponding to an actual amount of force being applied against the instrument distal end portion.
In accordance with still another embodiment, a method of diagnosing and/or treating internal body tissue includes maneuvering a distal end portion of an elongate instrument against an internal body tissue surface, sensing an axial force vector applied by the body surface to the instrument distal end portion, determining an angle of incidence at which the instrument distal end portion is contacting the body surface, and projecting, based on the sensed axial force vector and determined contact angle of incidence, a component of the axial force in a direction normal to the tissue surface at the contact location. Such method may further include projecting a component of the axial force vector in a direction tangential to the tissue surface at the contact location.
Other and further aspects and embodiments are disclosed in the following detailed description, which is to be read in conjunction with the figures.
The drawings illustrate the design and utility of illustrated embodiments of the invention, in which similar elements are referred to by common reference numerals, and in which:
Robotic interventional systems and devices such as the Sensei™ Robotic Catheter System and the Artisan™ Control Catheter manufactured and distributed by Hansen Medical, Inc., Mountain View, Calif., are well suited for use in performing minimally invasive medical procedures. Exemplary embodiments of robotic instrument systems that may be modified for constructing and using embodiments of the present invention are disclosed and described in detail U.S. patent application Ser. Nos. 11/073,363, filed Mar. 4, 2005, Ser. No. 11/179,007, filed Jul. 6, 2005, U.S. patent application Ser. No. 11/418,398, filed May 3, 2006, U.S. patent application Ser. No. 11/481,433, filed Jul. 3, 2006, and U.S. patent application Ser. No. 11/640,099, filed Dec. 14, 2006, which are all incorporated herein by reference in their entirety. Additionally, U.S. Patent Publication 2007/0233044 (the “'044 publication”), which is incorporated herein by reference in its entirety, discloses embodiments of such robotically-navigated interventional systems, including the capability to sense force between a surface of an internal body cavity or lumen (referred to collectively as a “body space”) and a distal end of a working instrument (e.g., an ablation catheter) carried in a working lumen of a robotically controlled guide instrument. The system not only detects contact between the instrument and the surface, but also measures the magnitude of the force, also called the load. In particular, the system can also be used to detect contact with tissue structures due to the change in the sensed force. Force sensing and force feedback capabilities may be provided by an Artisan™ Control Catheter and IntelliSense™ Fine Force Technology™ provided on the Sensei™ Robotic Catheter System manufactured and distributed by Hansen Medical, Inc.
One illustrative embodiment of a robotic instrument system (32) according to the present invention is shown in
The control station (2) also comprises a display (4) that is used to display various aspects of the robotic instrument system (2). For example, an image of the working instrument and guide instrument (described in further detail below) may be displayed in real time on the display (4) to provide the physician (12) with the current orientation of the various devices as they are positioned, for example, within a body lumen or region of interest. The control station (2) further comprises a computer assembly (6), which may comprise a personal computer or other type of computer work station for performing the data processing operations disclosed herein. The robotic catheter assembly (10) is coupled to the operating table (22) by an instrument driver mounting brace (26). The robotic catheter assembly (10) comprises a robotic instrument driver (16), a working catheter (18), and a guide catheter (30) (also referred to herein as an instrument guide catheter, guide catheter, robotic guide instrument, robotic guide catheter, or the like). The instrument driver mounting brace (26) of the depicted embodiment is a relatively simple, arcuate-shaped structural member configured to position the instrument driver (16) above a patient (not shown) lying on the table (22).
Referring to
The guide catheter (30) is mounted via a base (24) carrying the ditherer (50). The ditherer (50) is coupled to the working catheter (18) that is dithered back-and-forth relative to the guide catheter (30). The guide catheter (30) is coupled to housing (42) that mechanically and electrically couples the guide catheter (30) to a robotically-controlled manipulator. For example, the guide catheter (30) may be coupled to a robotically controlled instrument driver such as, for instance, the above-mention Sensei™ Robotic Catheter System manufactured and distributed by Hansen Medical.
Referring back to
As is described in greater detail herein, the system (32) further comprises a position determining system (70) for determining the position of the distal end (20) of the working catheter (18). The position determining system (70) may be any suitable localization system, many of which are commercially available, including without limitation localization systems that use magnetic or voltage potential sensors, such as the Carto™ XP available from Biosense Webster, Inc. (a subsidiary of Johnson & Johnson), the EnSite NavX™ available from St. Jude Medical, and the microBird™ available from Ascension Technology, each of which are which are capable of sensing the relative locations of each of a plurality of sensors (72) located on the catheter (18). The position sensing system (70) may also be a shape sensing system that employs fiber optic Bragg grating shape sensing, such as systems disclosed in U.S. patent application Ser. Nos. 11/690,116, filed Mar. 22, 2007, Ser. No. 12/106,254, filed Apr. 18, 2008, and Ser. No. 12/192,033, filed Aug. 14, 2008, and in U.S. Provisional Patent Application No. 61/003,008, filed Nov. 13, 2007, which are all incorporated herein by reference in their entirety. The position determining system (70) is in operable communication with a computer assembly (6) of the operator control station (2) through the communication link (14). The computer assembly (6) may comprise conditioning electronics for conditioning the force signals from the force sensor system (34) and the position signals from the position determining system (70).
Turning now to
In the embodiment illustrated in
By “dithering” the working catheter (18) with respect to the guide catheter (30), the repeated cyclic motion may be utilized to overcome frictional challenges normally complicating the measurement, from a proximal location, of loads at the distal end (20) of the working catheter (18) when in contact with a surface. In one embodiment, the dithering motion may be applied on a proximal region of the working catheter (18) as is illustrated in
To release this relatively tight coupling and facilitate proximal measurement of forces applied to the distal end (22) of the working catheter (18), dithering motion may be used to effectively break loose this frictional coupling. In the embodiment illustrated in
The issues presented by the frictional forces and other complexities associated with a force sensor located at the proximal end (22) of the working catheter (18) may be eliminated by locating the force sensor at or near the distal end (20) of the working catheter (18).
The working catheter (18) of
As briefly discussed above, the computer assembly (6) is configured to receive and process the force signals from the force sensor system (34) and the position signals from the position determining system (70). It should be understood that the computer assembly (6) may comprise one or more computers, signal conditioning electronics, and other displays and peripherals. The computer assembly (6) is also configured to process the force signals and position signals to generate a geometric map of an area of body tissue correlated to the tissue compliance of the tissue or other characteristic of the body tissue related to its tissue compliance.
As an example, as the working catheter (18) is robotically maneuvered within a patient's body at an area of interest, the distal end (20) is moved into contact with the plurality of locations on the area of body tissue. The computer assembly (6) receives the position signals and force signals and determines the force on the tip, the deflection of the tissue and the position of the location on the area of body tissue at each of the plurality of locations. The computer assembly (6) is further configured to generate a geometric map of the area of body tissue using the position determined for each location, and to also correlate the tissue compliance at each location and superimpose the tissue compliance on the geometric map. Regions of different compliance may be superimposed on the mapping in different colors, shades or other suitable representation. The computer assembly (6) may also be configured to relate the measured compliance of the different regions of the area of tissue to other tissue characteristics, such as tissue type, tissue condition (necrosed, healthy, diseased, etc.) or other characteristic of interest.
This approach is similar to that described in U.S. Pat. No. 5,391,199 to Ben-Haim et al. (the “'199 patent”), which is incorporated herein by reference in its entirety. The '199 patent discloses methods of detecting contact of the instrument tip with a body surface in combination with localization techniques to generate a graphic, geometric representation or “map” of a body structure, such as the surface surrounding a body lumen or cavity (e.g., a heart chamber). The '199 patent describes a geometric mapping of the walls of a body lumen or cavity using a manual catheter by sensing contact with a plurality of locations on the surface(s) of the lumen or cavity and using localization sensors to determine position coordinates of the instrument tip at each of the plurality of locations. This position data is then used to construct a geometric map of the body lumen or cavity.
Returning to the embodiments of
The 3-D mapping system (302) is capable of producing diagnostic data using time domain and frequency domain representations of electrophysiology data. Exemplary maps include time domain difference between action potentials at a roving electrode (e.g., an electrode coupled to a catheter) and a reference electrode; the peak-to-peak voltage of action potentials at the roving electrode; the peak negative voltage of action potentials at the roving electrode; complex fractionated electrogram information; a dominant frequency of an electrogram signal; a maximum peak amplitude at the dominant frequency; a ratio of energy in one band of the frequency-domain to the energy in a second band of the frequency-domain; a low-frequency or high frequency passband of interest; a frequency with the maximum energy in a passband; a number of peaks within a passband; an energy, power, and/or area in each peak; a ratio of energy and/or area in each peak to that in another passband; and a width of each peak in a spectrum. Colors, shades of colors, and/or gray scales are assigned to values of the parameters and colors, shades of colors, and/or gray scales corresponding to the parameters for the electrograms sampled by the electrodes are provided and updated on the three-dimensional map or model. One example of such a 3-D mapping system (302) is described in U.S. Patent Publication 2007/0073179, filed Sep. 15, 2005, the contents of which are fully incorporated herein by reference.
In one embodiment, illustrated in
As is described in greater detail herein, additional three-dimensional maps or models may be produced from points or locations acquired from the electrode (606) when the catheter (604) is slightly off of the surface and not quite contacting the surface or wall of the heart (600), but in sufficiently close proximity of the wall of the heart (600). Force sensing may be used in combination with a catheter equipped with one or more electrodes to plot, mark, or trace the surface or wall of the heart, with differing levels of applied force to produce various three-dimensional maps or models of the surface of the heart. In addition, force sensing data may be used to verify or calibrate the three-dimensional maps produced by a 3-D mapping system (302). That is, force sensing may be used to determine if a 3-D map is produced from points that are on the actual surface of the heart (600) or from points that are slightly off of the surface of the heart (600) based on force feedback information.
At step 1114, one or more force sensing catheters plot, mark, or trace the surface or wall of the cavity (described in greater detail herein). At step 1116, the force sensing system registers the forces transmitted from the force sensing catheter as the surface or wall of the cavity is plotted, marked, or traced and points that are actually on the surface or wall of the cavity are identified based on force feedback information. For example, a force threshold may be determined to indicate when the tip of the force sensing catheter is just touching the surface of the cavity (e.g., a substantially negligible force reading). Accordingly, a force reading above the force threshold may indicate that the tip of the force sensing catheter has pushed onto the surface of the cavity (surfaces of cavities in a patient are typically comprised of compliant tissues), such that the surface of the cavity may have deflected from its normal state. Furthermore, a force reading below the force threshold may indicate that the tip of the force sensing catheter may not be touching the surface of the cavity.
At step 1118, the force sensing system registers the forces transmitted from the force sensing catheter as the surface or wall of the cavity is plotted, marked, or traced and points that are slightly below the surface or wall of the cavity are identified based on force feedback information. At step 1120, the force sensing system registers the forces transmitted from the force sensing catheter as the surface or wall of the cavity is plotted, marked, or traced and points that are slightly above the surface or wall of the cavity are identified based on force feedback information. At step 1122, the system generates a three-dimensional map or models of the tissue walls defining the cavity based on the collected position data points that are determined (based on the sensed force) to be actually on the cavity wall surface, along with points that are slightly below the surface or wall of the cavity, and points that are slightly above the surface or wall of the cavity.
Thus, in accordance with one embodiment, the process for mapping an area of internal body tissue includes: (a) maneuvering a distal end portion of an elongate instrument within an interior body region; (b) determining a position of the instrument distal end portion within the body region; (c) sensing a force applied to the instrument distal end portion at the determined position; (d) repeating acts (a) to (c) for a multiplicity of determined positions of, and sensed forces applied to, the instrument distal end portion within the interior body region; and (e) processing the respective determined positions and sensed forces for the multiplicity of determined positions to generate a geometric rendering of an internal body tissue surface located within the interior body region. In one embodiment, processing the respective determined positions and sensed forces to generate a geometric rendering of the internal body tissue surface comprises identifying a plurality of determined positions of the instrument distal end portion within the interior body region at which a substantially same amount of applied force is detected.
At step 1124, a comparison (i.e., to verify or calibrate) the three-dimensional map(s) produced by the conventional three-dimensional mapping system during operation 1110 with the three-dimensional map(s) produced from points identified or determined by the force sensing catheter, and in operation 1126, appropriate adjustments or modifications are made to the three-dimensional map produced by the conventional three-dimensional mapping system.
For purposes of illustration,
The electrical potential of the guide electrode (604-1) on the guide catheter (604) of the instrument assembly (1208) may be compared to the electrical potentials to the various pairs of electrodes (e.g., 402 and 404, 406 and 408, 402 and 410, etc.) to determine the x, y, and z positions or coordinates of the guide electrode (604-1). For example, the guide electrode (604-1) may have an electrical potential reading of 10 mV, and the electrical field electrodes (402 and 404) may have respective electrical potential readings of 5 mV and 15 mV. Accordingly, the guide electrode (604-1) may be located substantially in the middle of the field electrode (402) and field electrode (404). Alternatively, the field electrodes (402 and 404) may have respective y-coordinates of y=5 and y=15, while the guide electrode (604-1) may have a y-coordinate of y=10. Following a similar process, the spatial position or three-dimensional coordinates of the guide electrode (604-1) may be determined. Executing a similar process for all the electrodes (604-1, 604-2, 604-3, . . . , 604-n, and 602-1, 602-2, 602-3, . . . , 602-n), the spatial positions or three-dimensional coordinates for all the electrodes coupled to the instrument assembly may be determined.
The aforementioned three-dimensional maps or models as discussed in the foregoing detailed description may be combined with the spatial positions or three-dimensional coordinate information as discussed above, such that the relative position of an object in a volume or cavity may be determined. Such information as applied to minimal invasive procedures would be very useful to a surgeon who is performing such procedures on a patient. In other words, the surgeon is able to “see” where a surgical instrument is located in a patient's body, where a surgical instrument is located in an organ where the minimal invasive procedure is being performed, and where or how close the surgical instrument is located to the spot where the operation has to be executed.
In some situations, the reference frame or coordinate system of the three-dimensional model of the volume or cavity of the patient may not align with the reference frame or coordinate system (e.g., as associated with fluoroscopy, optical fiber position and shape sensing, electrodes in an electrical field, etc.) of the objects (such as an instrument assembly (108)) that are advanced or navigated into the volume or cavity of the patient. As such, in some situations it may be useful to align the reference frame or coordinate system of the three-dimensional model of the volume or cavity of the patient with the reference frame or coordinate system of the objects that are advanced or navigated into the volume or cavity of the patient. Various reference frame or coordinate system alignment, transformation, translation, rotation, etc. methodologies (e.g., Euler, etc.) may be used to align the reference frames or coordinate systems. For example, in order to align the two reference frames or coordinate systems, one or both of the coordinate systems may be translated in one or more of the axes (x-axis, y-axis, and z-axis). In addition, one or both of the coordinate systems may be rotated along one or more of the axes (x-axis, y-axis, and z-axis) to achieve alignment. Alignment or re-alignment the reference frames or coordinate systems may need to be repeated throughout the minimally invasive operation to ensure accurate spatial and positional information.
In one embodiment, a robotic surgical system may include programmable instructions to operate the instrument driver to drive, advance, steer and operate any tools or instruments coupled to the guide catheter and/or sheath catheters of the instrument assembly to be within the boundary of one of the three-dimensional maps. In another embodiment, the guide catheter and/or sheath catheter may include control wires that are coupled to circuitry (e.g., parallel circuits, etc.) that is capable of identifying when any one of the control wires is broken.
Thus, in accordance with a main embodiment of the disclosed the invention, a robotic instrument system includes a controller, an instrument driver in communication with the controller, and an elongate instrument coupled to the instrument driver, the instrument driver configured to manipulate a distal end portion of the guide instrument in response to control signals generated by the controller. A force sensing system may be coupled directly to the instrument (e.g., embedded in a wall portion at or near the instrument distal end), and the robotically driven instrument may itself be a working instrument, e.g., having mapping and/or ablation electrodes or other operative elements on its distal end. In other embodiments, the robotically controlled instrument is a guide instrument having a working lumen in which a separate working instrument, such as a mapping and/or ablation catheter, is coaxially disposed, in which case the force sensing system is preferably coupled directly to the working instrument. The force sensing system may comprises one or more sensors (e.g., strain gauges) embedded in or otherwise coupled to the distal end portion of the respective instrument, or at some other location. In one embodiment, the force sensing system is the above described “dithering” system that is coupled to a proximal portion of a working instrument that extends proximally from the robotic guide instrument.
The force sensing system may be a unidirectional, for example, only sensing forces applied substantially normal to a longitudinal axis of the instrument; or it may be a multi-directional force sensing system. In the case of unidirectional force sensing along the axis of the respective elongate instrument, the system processor may still calculate an estimated applied force normal to a tissue surface even where the respective force sensing instrument is pressed against the tissue surface at a non-orthogonal angle, as long as the relative positions of the instrument and tissue surface are known. By way of illustration,
Thus, the force sensing system is configured to generate force signals responsive to a force applied by a tissue surface to a distal end portion of the respective guide or working instrument normal to the tissue surface. Similarly, a position determining system is part of or otherwise integrated with the robotic instrument system, the positioning system including one or more position sensors that generate position data indicative of a position of the distal end portion of the respective guide or working instrument (hereinafter, “sensing instrument”) where applicable). A processor, which may incorporated as part of the system controller, or a separate processor in communication with the controller, is operatively coupled to the respective force sensing and position sensing systems. The processor generates and causes to be displayed on a display associated with the system a geometric rendering (or “map”) of an internal body tissue surface based at least in part upon sensed forces applied to the distal end of the sensing instrument as it is maneuvered within an interior region of a body containing the body surface.
By way of illustration,
Maneuvering of the guide instrument 205 within the anatomical workspace 217 may be accomplished under operator control, or automated under system control, or some of each. By way of non-limiting example, the system may be configured to maneuver the guide instrument 205 along a predetermined set of trajectories that explore the workspace 217 based on its approximate dimensions obtained, also by way of non-limiting example, from an imaging system, such as fluoroscopic image data. The trajectories are preferably calculated by the system in order to obtain an adequate amount of force and position data to construct a reliable structural map of the tissue surface boundary 213 (or a portion thereof) of the workspace 217. Such trajectories may be configured to obtain a three-dimensional grid of points (“tapper-mapper”) or to stay along fixed radial lines (e.g., line 237 in
Even if an automated process is employed to obtain the necessary force/position mapping data, the system preferably displays a representation of the anatomical workspace 217 to the operator so that the operator may maneuver the guide instrument 205 to portions of the anatomy to be mapped that are not captured by the automated mapping process. It will be appreciated that, as the working instrument tip 211 is moved about the workspace 217, it will periodically come into contact with the tissue surface 213, whether by purposeful or random trajectory of the guide instrument 205, allowing for accumulation of respective force and position data adequate to generate a reliable structural map of the tissue surface 213. It will also be appreciated that when obtaining the force and associated position data for a heart chamber of a beating heart, well-known filtering or heart rhythm gating techniques must be employed. If contact with the tissue surface is not sensed at the limit of the guide workspace (i.e., the limit to which the guide instrument 205 can be safely extended along a particular trajectory), the system preferably records that no contact was detected. When all of the trajectories have been traversed by the system, a three-dimensional map of the explored workspace is displayed to the operator, preferably also showing any areas where the guide instrument 205 reached its own workspace limit with no resistance, so that the operator may take those locations into account for further planning purposes.
By way of further example,
In one variation available for certain regions and anatomical workspaces in the body, especially where the fluid in the organ chamber to be mapped is relatively clear, such as in the kidney shown
In another variation, the mapping process is conducted automatically. The physician first defined a region of abnormality to be mapped on an image model created by the computer in the control counsel. A commend is then given to the computer in the control counsel to direct the distal tip of the robotic catheter to scan/touch/palpate the surface of the defined region to be mapped. In one example, the computer controls a catheter carrying the force sensor to dither over the surface of the defined region. In another example, the computer controls the catheter to glide the force sensor on the catheter over the defined region. Once the command to automatically map the plasticity/tissue-characteristic of the define region is given, the physician may monitor the mapping process through one or more of the following mechanisms or a combination thereof: (1) direct visualization through the imaging modality integrated within the robotic catheter; (2) the force sensor output being display on monitor at the control counsel; (3) real time imaging (e.g., fluoroscope, MRI, ultrasound, etc.) of the organ; (4) a computer model (e.g., computer generated cartoon) of the organ's internal space along with a moving catheter model indicating the position of the catheter within the organ's internal space. Further embodiments of a robotic instrument system that can be used for such alternate embodiments are shown in
It will be appreciated that the boundaries of a generated and displayed geometric map necessarily depends on the threshold level of force applied to the distal end of the sensing instrument at which the system (whether based on operator input or otherwise automated) determines the instrument tip is contacting the tissue surface. In one embodiment, an amount of force indicative of tissue surface contact may be derived by obtaining sample data by maneuvering the sensing instrument directly into one or more locations on the tissue surface to be mapped up to a maximum threshold force level. While the sensing instrument tip remains in an open space and not contacting any tissue structure within the workspace, a relatively low level of force is applied to the instrument tip, e.g., just that exerted by the patient's blood pressure along with inherent system friction when navigating in the blood vessel system. However, as the instrument approaches and contacts a tissue surface, the applied force will ramp up, with a steepness of the ramp (or curve) being a function of the tissue surface stiffness or compliance. Thus, by viewing and/or analyzing one or more sample force curves, the operator (if done manually) and/or the system processor can identify a point along the curve in which it is readily apparent that tissue surface contact has been made.
For purposes of illustration,
As previously stated, the boundaries of a geometric tissue surface map generated in accordance with the force sensing techniques described herein will necessarily vary depending on the selected threshold level of applied force chosen as representative of “tissue contact”. Thus, it may be beneficial to chose a force level that is clearly over (or at least slightly over) the actual level indicating initial surface contact in order to achieve consistent results from map to map. Another approach, shown in
Regardless of the data collection technique that is employed, the processor can produce a graphic rendering of respective “tissue surfaces” generated based on differing force levels, similar to a topography map. By way of illustration,
One aspect of this embodiment is that areas in the tissue surface having a markedly different compliance are readily detected based on the relative spacing between the first and second surface boundaries, 293 and 291. In particular, at locations 294, the spacing between the two force level boundaries is relatively wide, indicating a corresponding relatively high tissue compliance; whereas the spacing between the two force level boundaries is very slight at locations 293, indicating a corresponding low compliance (i.e., high stiffness) of the tissue at those locations. This difference in tissue compliance (stiffness) can be indicative of different types of tissue at the respective locations, e.g., scar tissue versus healthy muscle or even fatty tissue. In one embodiment, the system processor is configured to automatically determine a characteristic of an area of the surface tissue based on the relative spacing between respective force-level surface boundaries, and in particular a characteristic based on tissue compliance.
It may be desirable to provide force-feedback (e.g., through a haptic operator input interface), along with the automatic limiting and stabilization of an applied force exerted on the tissue surface during a mapping procedure. Operation of one embodiment having these features is shown in
It should be appreciated that the force applied by the instrument in the forgoing example illustrated in
The processor is preferably configured to determine a characteristic of tissue (e.g., tissue stiffness or compliance) at a location on the tissue surface based on a sensed force applied to the distal end portion of the instrument, as the instrument is maneuvered against the tissue surface at the respective location(s). As previously described with respect to the various embodiments disclosed herein, a display may be coupled to the system processor for displaying geometric renderings of respective internal body tissue surfaces and passageways, for example, wherein regions of the body tissue area in the map having differences in tissue compliance are visually highlighted. By way of example,
In one such embodiment, treating the tissue anomaly includes one or more of determining approximate boundaries of the tissue anomaly on the tissue surface; displaying approximate boundaries of the tissue anomaly on a graphic rendering of the tissue surface; delivering treatment energy to the anomaly; delivering a treatment substance to the anomaly; and displaying an area of the anomaly that has been treated on a graphic rendering of the tissue surface. Again, one or both of delivering treatment energy to the anomaly and delivering a treatment substance to the anomaly are performed using the instrument.
While multiple embodiments and variations of the many aspects of the disclosed invention have been described herein, such description is provided for purposes of illustration only. Many combinations and permutations of the disclosed embodiments are useful in minimally invasive medical diagnosis and intervention, and the disclosed inventions are configured to be flexible and adaptable. In particular, the foregoing illustrated and described embodiments of the disclosed inventions are suitable for various modifications and alternative forms, and it should be understood that the disclosed inventions generally, as well as the specific embodiments described herein, are not limited to the particular forms or methods disclosed, but also cover all modifications, alternatives, and equivalents as defined by the scope of the appended claims. Further, the various features and aspects of the illustrated embodiments may be incorporated into other embodiments, even if not so described herein, as will be apparent to those skilled in the art. In addition, although the description describes data being mapped to a three dimensional model, data may be mapped to any mapping or coordinate system, including two dimensional, static or dynamic time-varying (temporal) map, coordinate system, model, image, etc. All directional references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, etc.) are only used for identification purposes to aid the reader's understanding of the disclosed inventions without introducing limitations as to the position, orientation, or applications of the invention. Joining references (e.g., attached, coupled, connected, and the like) are to be construed broadly and may include intermediate members between a connection of elements (e.g., physically, electrically, optically as by an optically fiber, and/or wirelessly connected) and relative physical movements, electrical signals, optical signals, and/or wireless signals transmitted between elements. Accordingly, joining references do not necessarily infer that two elements are directly connected in fixed relation to each other.
The present application claims the benefit under 35 U.S.C. § 119 to U.S. Provisional Patent Application Ser. No. 60/964,915, filed on Aug. 15, 2007. The present application is also related to U.S. patent application Ser. No. 12/150,109, filed on Apr. 23, 2008. The foregoing applications are hereby incorporated by reference into the present application in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60964915 | Aug 2007 | US |
