Abstract:
Apparatus for controlling a steerable invasive probe having a handle. The apparatus includes a platform and a jig, which is mounted on the platform and is configured to receive the handle. The jig includes at least a first gear that is positioned and shaped to rotate the handle about an axis of the probe and a second gear that is positioned and shaped to operate a control on the handle for deflecting a tip of the probe. A drive module includes one or more motors. A transmission is coupled to the drive module and to the jig so as to controllably rotate at least the first and second gears and to translate the platform along a direction parallel to the axis in order to advance and retract the probe.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to invasive medical instruments, and specifically to methods and apparatus for manipulating and steering an invasive probe for diagnostic or therapeutic purposes. 
       BACKGROUND OF THE INVENTION 
       [0002]    Various types of robotic steering mechanisms for catheters are known in the art. For example, U.S. Patent Application Publication 2005/0203382, whose disclosure is incorporated herein by reference, describes a robot for steering a catheter that is designed to be manually manipulated by a user. The catheter has a user-operable control handle or a thumb control, and the robot holds and manipulates the catheter by generally mimicking the motions of a hand of a surgeon. 
         [0003]    As another example, PCT International Publication WO 99/45994, whose disclosure is incorporated herein by reference, describes a remote control catheterization system including a propelling device, which controllably inserts a flexible, elongate probe into the body of a patient. A control console, in communication with the propelling device, includes user controls which are operated by a user of the system remote from the patient to control insertion of the probe into the body by the propelling device. 
       SUMMARY OF THE INVENTION 
       [0004]    Embodiments of the present invention that are described hereinbelow provide a robotic drive for an invasive medical device, such as a catheter, that enables versatile, precise control of the motion of the device inside the patient&#39;s body. 
         [0005]    There is therefore provided, in accordance with an embodiment of the present invention, apparatus for controlling a steerable invasive probe having a handle. The apparatus includes a platform and a jig, which is mounted on the platform and is configured to receive the handle. The jig includes at least a first gear that is positioned and shaped to rotate the handle about an axis of the probe and a second gear that is positioned and shaped to operate a control on the handle for deflecting a tip of the probe. A drive module includes one or more motors. A transmission is coupled to the drive module and to the jig so as to controllably rotate at least the first and second gears and to translate the platform along a direction parallel to the axis in order to advance and retract the probe. 
         [0006]    In a disclosed embodiment, the second gear is positioned and shaped to rotate a first control wheel for deflecting the tip of the probe in a first direction relative to the axis, and the jig includes a third gear, which is positioned and shaped to rotate a second control wheel on the handle for deflecting the tip of the probe in a second direction, perpendicular to the first direction. 
         [0007]    The first and second gears may be configured to encircle the handle. 
         [0008]    In some embodiments, the transmission includes at least first and second telescopic drive modules, which are respectively coupled to drive the first and second gears over a range of locations of the platform. Typically, each of the telescopic drive modules includes a driving shaft, which is fixedly coupled to be rotated by a respective motor, and a driven shaft, which is fixedly coupled to the jig so as to move with the platform along the direction parallel to the axis, while slidably engaging the driving shaft so as to be rotated by the driving shaft. 
         [0009]    There is also provided, in accordance with an embodiment of the present invention, an invasive medical system, including a steerable invasive probe having an axis and a distal tip for insertion into a body of a subject, and including a handle and at least one control on the handle for controlling a deflection of the distal tip. A robotic drive, includes a platform and a jig, which is mounted on the platform and is configured to receive the handle, and which includes at least a first gear that is positioned and shaped to rotate the handle about the axis of the probe and a second gear that is positioned and shaped to operate the at least one control. A drive module includes one or more motors. A transmission is coupled to the drive module and to the jig so as to controllably rotate at least the first and second gears and to translate the platform along a direction parallel to the axis in order to advance and retract the probe. A control unit is coupled to control the drive module so as to move the probe inside the body. 
         [0010]    In a disclosed embodiment, the probe includes a catheter, which is configured for insertion into a heart of the subject. 
         [0011]    In some embodiments, the system includes a position-sensing subsystem, for determining position coordinates of the probe inside the body, wherein the control unit is configured to control the drive module responsively to the position coordinates. Typically, the position-sensing subsystem includes a position transducer in the distal tip of the probe. 
         [0012]    There is additionally provided, in accordance with an embodiment of the present invention, a method for controlling a steerable invasive probe having a handle. The method includes inserting the handle into a jig, which is mounted on a platform and which includes at least a first gear that is positioned and shaped to rotate the handle about an axis of the probe and a second gear that is positioned and shaped to operate a control on the handle for deflecting a tip of the probe. A transmission is coupled to a drive module, including one or more motors, and to the jig so as to controllably rotate at least the first and second gears and to translate the platform along a direction parallel to the axis in order to advance and retract the probe. 
         [0013]    The present invention will be more fully understood from the following detailed description of the embodiments thereof, taken together with the drawings in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a schematic, pictorial illustration of a catheterization system with a robotic drive, in accordance with an embodiment of the present invention; 
           [0015]      FIG. 2  is a schematic, pictorial illustration showing a catheter held in a robotic drive, in accordance with an embodiment of the present invention; 
           [0016]      FIGS. 3A and 3B  are schematic side and top views, respectively, of a robotic drive for a catheter, in accordance with an embodiment of the present invention; 
           [0017]      FIG. 4  is a schematic side view of a jig used to grip a catheter in a robotic drive, in accordance with an embodiment of the present invention; 
           [0018]      FIG. 5A  is a schematic, pictorial illustration of a set of gears used in controlling a catheter, in accordance with an embodiment of the present invention; 
           [0019]      FIG. 5B  is a schematic side view of a catheter handle including rotary controls that are engaged by the gears of  FIG. 5A  in accordance with an embodiment of the present invention; and 
           [0020]      FIGS. 6A and 6B  are schematic, pictorial illustrations of driving and driven subassemblies, respectively, of a transmission used in driving a catheter, in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0021]    Embodiments of the present invention provide a robotic drive that carries out all four types of motion that can normally made by a human operator of a catheter or other steerable probe:
       1. In/out (forward/back—advancing the catheter tip farther into the target organ or retracting it outward);   2. Rotation (roll) about the catheter axis;   3. Right/left deflection of the catheter tip;   4. Up/down deflection of the catheter tip.
 
(For some applications, one direction of deflection is sufficient, since the catheter may be rotated about its axis in order to align the deflection in the desired direction. The second direction of deflection may therefore be considered an additional, optional feature.)
       
 
         [0026]    The catheter may be of a standard type, designed for manual control by a human operator, with one or more controls on the handle to control right/left and up/down deflection. In the embodiment pictured below, the controls on the handle have the form of rotatable control wheels, and the robotic jig grips each of these wheels in a gear, and grips the handle itself in another gear. Alternatively, the gears in the jig may be configured to drive controls of other types, such as linear controls. 
         [0027]    Each gear is driven by a respective motor via a telescopic transmission shaft assembly (“telescopic” in the sense that the length of the assembly can change during operation). The gears may be driven separately or in concert in order to perform all of the latter three motions in the list above and thus give any desired orientation of the catheter tip. A motorized linear drive moves the entire jig forward and back on a platform to provide in/out motion of the catheter along its axis. 
         [0028]      FIG. 1  is a schematic, pictorial illustration of a catheterization system  20  with a robotic drive  26 , in accordance with an embodiment of the present invention. In the illustrated embodiment, a catheter  22  is inserted into a body cavity  24 , such as a chamber of the heart of a subject. The distal tip of the catheter (shown enlarged in the inset) typically comprises a functional element  28  for diagnostic and/or therapeutic purposes. For example, element  28  may comprise an electrode for electrical sensing and/or ablation of tissue, or an ultrasonic transducer for intracardiac imaging. Other types of functional elements and invasive probes that may be driven in the manner described below will be apparent to those skilled in the art and are considered to be within the scope of the present invention. 
         [0029]    In the pictured embodiment, catheter  22  also comprises a position transducer  30  within its distal tip, for use in determining position coordinates of the tip. For example, transducer  30  may comprise a magnetic field sensor, which detects magnetic fields generated by field transducers  32  at known locations outside the body. Magnetic position sensing systems of this sort are described, for example, in U.S. Pat. No. 5,391,199, whose disclosure is incorporated herein by reference, and are used in intracardiac tracking systems, such as CARTO™ (produced by Biosense Webster Inc., Diamond Bar, Calif.). Alternatively, transducer  30  may generate fields to be sensed by transducers  32 . Further alternatively or additionally, transducer  30  may comprise any other suitable type of position transducer known in the art, such as an electrode for purposes of impedance-based position sensing, an ultrasonic transducer, or a fiducial mark for locating the catheter tip in a two- or three-dimensional image of the body. 
         [0030]    A position-sensing module  34  communicates with transducers  30  and  32  in order to determine the position coordinates of the catheter tip inside the body of the subject. A control unit  36  uses the coordinates to control drive  26  in order to navigate catheter  22  to desired positions within the body. In this respect, control unit  36  may operate autonomously, in accordance with predefined program instructions. Alternatively or additionally, the control unit may present the catheter position on a display  38 , typically juxtaposed on a map or image of cavity  24 , so as to enable a human operator (not shown) to control the catheter. Control unit  36  typically comprises a general-purpose computer processor, which is programmed in software to carry out the desired functions. 
         [0031]      FIG. 2  is a schematic, pictorial illustration showing catheter  22  held in robotic drive  26 , in accordance with an embodiment of the present invention. Catheter  22  comprises a handle  40 , which is designed to be held and manipulated by a human operator. In conventional use, the operator inserts the distal end of the catheter percutaneously into a blood vessel, and then advances the catheter along its longitudinal axis through the blood vessel into cavity  24 . The operator uses two control wheels on handle  40  (shown below in  FIG. 5B ) to deflect the distal end of the catheter in respective, mutually-perpendicular directions relative to the catheter axis. The operator moves the handle back and forth in order to advance and retract the catheter, and may also rotate the handle about the axis in order to rotate the catheter itself. A proximal terminal  42  connects the catheter to control unit  36 , but this connection is omitted from  FIG. 2  for the sake of simplicity and clarity of illustration. 
         [0032]    In the present embodiment, however, drive  26  carries out these manipulations instead of the human operator. A jig  44  holds handle  40 . The jig comprises one gear (or set of gears) for rotating the handle about the axis and other gears for rotating the control wheels on the handle (as shown below in  FIGS. 4 and 5A ). Jig  44  is mounted on a platform  46 , which is capable of translating relative to a base  47  in order to advance and retract the catheter along its axis. A drive module  48  is coupled by a transmission  50  to jig  44  in order to rotate the gears and to translate platform  46  along base  47 . The components of the jig and drive module are shown in greater detail in the figures that follow. 
         [0033]      FIGS. 3A and 3B  are schematic side and top views, respectively, of robotic drive  26 , in accordance with an embodiment of the present invention. Drive module  48  comprises four electric motors  52 , such as miniature stepper or servo motors, which are controlled by control unit  36  ( FIG. 1 ). In this embodiment, the lower motor (in the view seen in  FIG. 3A ) is connected by a linear drive  58  to advance and retract a shaft  60 . As this shaft advances or retracts, it moves platform  46  relative to base  47 , and thus advances or retracts jig  44  and catheter  22 . In this manner, catheter  22  is advanced and retracted inside the subject&#39;s body. 
         [0034]    The three upper motors  52  are coupled to telescopic drive modules, each comprising a driving shaft  54  and a driven shaft  56 . The driving shaft is fixedly coupled to be rotated by the respective motor, while the driven shaft is fixedly coupled to jig  44  so as to move with platform  46  while slidably engaging the driving shaft. This telescopic arrangement, which is shown in greater detail in  FIGS. 6A and 6B , enables driven shafts  56  to be rotated by driving shafts  54  over a large range of longitudinal positions of the platform. 
         [0035]    As noted above, jig  44  holds handle  40  of catheter  22 , while the catheter itself protrudes out through a collar  62 . After the handle is inserted into the jig, a cover  64  encloses and secures the handle in place. The handle is encircled by gears (shown in the figures that follow), which are driven by gears  66  on shafts  68 . These shafts are respectively connected to rotate as continuations of driven shafts  56 . In the pictured embodiment, each shaft  68  has a pair of gears  66  for more 
         [0036]      FIG. 4  is a schematic side view of jig  44 , in accordance with an embodiment of the present invention. This figure shows gears  70 ,  72  and  74 , which encircle the catheter handle (not shown in this figure) and are able to rotate freely within jig  44 . Each of gears  70 ,  72  and  74  is rotated by one of gears  66  on a respective shaft  68 . The longitudinal position of each of gears  66  determines which one of gears  70 ,  72  and  74  it will rotate. 
         [0037]    Reference is now made to  FIGS. 5A and 5B , which show further details of the manner of operation of jig  44 , in accordance with an embodiment of the present invention.  FIG. 5A  is a schematic, pictorial illustration of a set  80  of gears  70 ,  72  and  74 .  FIG. 5B  is a schematic side view of catheter handle  40 , including control wheels  82  and  84 , which are engaged by gears  70  and  72 . Rotating each of these control wheels deflects the distal tip of catheter  22  in a respective direction. (Both control wheels may be rotated together to give a diagonal deflection.) 
         [0038]    In preparation for operation of drive  26 , gears  70 ,  72  and  74  are slid over handle  40  so that gear  70  encircles and grasps wheel  82 , while gear  72  encircles and grasps wheel  84 . Gear  74  holds handle  40  itself, and the internal shape of this gear is, in this example, squared off in order to maintain a firm grip on the handle. Gears  70 ,  72  and  74  rotate independently, under control of driving gears  66 , in order to enable drive  26  to rotate and deflect catheter  22  to any desired orientation. 
         [0039]      FIGS. 6A and 6B  are schematic, pictorial illustrations of driving and driven subassemblies, respectively, of a transmission used in driving a catheter, in accordance with an embodiment of the present invention. The driving subassembly, shown in  FIG. 6A , comprises driving shafts  54  and linear drive  58 , which are fixedly connected to respective motors  52  in drive module  48 . Shafts  54  have an irregular (not circularly-symmetrical) cross-sectional profile. Drive module  48  is mounted on base  47 , which contains a track  90  for receiving platform  46 . 
         [0040]    The driven subassembly, shown in  FIG. 6B , is mounted on platform  46  and thus translates longitudinally relative to the driving subassembly. The subassemblies are coupled to one another by a coupling subassembly  92 , which contains nuts  94  attached to respective driven shafts  56 . Nuts  94  are shaped to match the profiles of driving shafts  54 , which will thus slide in and out telescopically through the nuts as platform  46  moves back and forth in track  90 . Rotation of driving shafts  54 , however, will drive concomitant rotation of driven shafts  56 , regardless of the relative longitudinal locations of the shafts. Thus, drive  26  maintains consistent control of the orientation of catheter  22  as the catheter is advanced into and retracted from the body. 
         [0041]    Drive mechanisms of the type described above can be used to drive two catheters to operate at the same time. For example, one of the catheters may be used for a therapeutic purpose, such as ablation treatment, while the other captures ultrasonic images of the therapeutic catheter. An application of this sort is described in U.S. Patent Application Publication 2007/0106147, whose disclosure is incorporated herein by reference: The ultrasound catheter is controlled robotically to ensure that the catheter is pointed toward the appropriate target, such as the therapeutic catheter. The position sensing system determines the direction in which the catheter should be pointed and measures any deviations from this direction, using a magnetic position sensor in the catheter. It then corrects the catheter position and orientation automatically, using the robotic drive mechanism, to keep the therapeutic catheter in its field of view. 
         [0042]    Although the above embodiments relate, for the sake of clarity of explanation, specifically to catheter  22 , the principles of the present invention may similarly be applied to other types of steerable invasive probes, such as endoscopes. The specific shapes and configurations of the components of drive  26  that are shown in the figures are adapted for the specific shape and properties of the catheter. Alternative configurations, for achieving similar functionality in connection with catheter  22  or with other types of invasive probes, will be apparent to those skilled in the art on the basis of the above description and are considered to be within the scope of the present invention. 
         [0043]    It will thus be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.