Patent Publication Number: US-2013253469-A1

Title: Handle for steerable catheter

Description:
FIELD OF THE INVENTION 
     The present invention relates to medical devices in general and to steerable imaging devices in particular. 
     BACKGROUND OF THE INVENTION 
     On most handles for a steerable imaging device, the relationship between the handle controls and the motion of the device is fixed. On some devices, however, the “up” direction as viewed on the TV monitor will probably not be the same as the “up” direction on a handle of the device. This occurs when the imaging device can rotate relative to a surrounding catheter or within the patient&#39;s body. As a result, the physician must move the controls to the left (for example) in order to steer the catheter in the “up” direction on the TV monitor. If the imaging device rotates again, the physician must re-determine which control direction corresponds to the “up” direction on the screen. This process is not only cumbersome but increases the required time to complete an examination. 
     SUMMARY OF THE INVENTION 
     To address the problems discussed above, the present invention is a handle configuration and steering mechanism that can be rotated in the user&#39;s hand such that the “up” direction on the handle can always be aligned with the “up” direction of images produced on a screen. The handle may also include a rotating collar or other device to indicate which direction on the handle corresponds to the “up” direction on the screen. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  illustrates a conventional  4 -wire actuation handle for use in controlling the direction of a steerable catheter; 
         FIG. 2  is a handle for use with a steerable catheter according to an embodiment of the present invention; and 
         FIG. 3  is a rotatable grip for use with a steerable catheter in accordance with another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As discussed above, the present invention is a handle that includes a steering mechanism for controlling the direction of a device to be inserted into a patient and that such device either produces images from within the body or whose position is imaged externally, such as by fluoroscopy, ultrasound, etc. The steering mechanism may be formed in a number of ways and be used with a variety of devices. In one embodiment, the steerable device is a multi-lumen catheter having one or more of the lumens dedicated to an imaging fiber and illumination fibers. The imaging and illumination fibers facilitate the transmittal of a visual image from inside the body to a physician or video camera. Alternatively, the catheter may include a solid state imaging sensor, such as a CCD or CMOS imaging chip. Another one or more of the lumens in the catheter are dedicated to pull wires that articulate the distal tip of the catheter. The pull wires have their distal ends secured at or adjacent the distal end of the catheter and their proximal ends connected to an actuator in the steering mechanism. Pulling one of the pull wires causes compression in one side of the catheter at the distal tip, which causes it to bend or articulate in that direction. 
     Utilizing four pull wires in four lumens allows four-way (left, right, up and down) motion. Some steerable catheters only utilize one pull wire and have only one direction of motion, while others utilize two wires for bi-directional motion. The present invention is most applicable to a four-wire system, but systems with fewer wires can also benefit. 
     One method of actuating the pull wires is shown in  FIG. 1 . The steering mechanism includes a handle  20  with four pull wires  22 , wherein proximal ends of the four pull wires are connected to the corners of an actuation plate  10 . The steering mechanism includes a frame that supports a spherical ball and the attached actuation plate  10  so that the ball  12  can rotate between a front bearing  14  and a rear bearing  16 , under direction of a lever arm  18 . When the lever arm  18  is moved in a certain direction, the net result is that one or two of the four pull wires  22  are pulled. As is already known to those in the art, the resultant pull on the wires actuates the steerable tip of the catheter. This particular handle  20  is designed so that motion of the distal tip corresponds to the motion of the actuation lever—if the lever is moved down, then the distal tip of the catheter is also moved down. 
     The problem with the arrangement shown in  FIG. 1  is that the handle  20  remains fixed with respect to the orientation of the lever arm  18 . If the imaging device becomes rotated with respect to a catheter in which it is placed or the catheter is rotated with respect to a patient, movement of the lever arm in the “up” (or other) direction no longer corresponds to an “upward” (or other) movement of the image on a display. For example, the “up” direction of the visualization probe could be aligned with the “left” direction of the catheter. In this example, when the physician wants to steer the catheter towards the top of the video screen, he must actually move the control lever in a leftward direction. If the handle could be easily re-oriented such that “up” relative to the physician corresponds to “left” relative to the steering controls (which thus corresponded to “up” on the video screen), then the task of steering the tip of the catheter would be greatly simplified. 
     The present invention is a handle that controls a steerable catheter in a way that allows a user to easily re-orient the steering device such that movement of the pull wires in a direction produces movement of the image produced in a similar direction. Although the invention is described with respect to aligning an upward movement on a display with movement of the steering mechanism in a particular reference direction, it will be appreciated that movement in any direction can form a reference direction. 
     As shown in  FIG. 2 , a handle  50  according to one embodiment of the invention contains the same lever arm  18  and catheter steering mechanism as shown in  FIG. 1 , but has an exterior shape that is basically symmetric about a central axis and can be held in the user&#39;s hand in any orientation. The physician can grasp the outer diameter surface of the handle  50  with the palm and fingers in a substantially vertical orientation (like a water glass), then use the thumb to operate the lever arm  18 . If the physician discovers (for example) that a leftward motion of the lever arm  18  is needed to create an upward motion of the distal tip, then he could grasp the handle  50  ninety degrees clockwise so that now an upward motion of the lever arm  18  will cause an upward motion of the tip of the catheter. 
     The handle  50  may also include a rotatable ring  52  that can spin around the handle body, but will remain in place due to friction or other means if it is left alone. This ring  52  could include a visual marker  54  that indicates which direction is “up”. Thus once the physician finds out which direction on the handle  50  corresponds to “up” on the screen, he can rotate the ring  52  such that the visual marker  54  is aligned with the “up” direction. This facilitates keeping the handle  50  aligned in the proper orientation and allows the user to put the handle down and pick it back up again without losing the proper orientation. 
     One particular application of the handle  50  of the present invention is for use with a fiber optic visualization catheter used in viewing the biliary tract. Such a catheter is normally introduced into the area of the biliary tract via a duodenoscope of the type well known in the art. A further improvement to the above handle would include a means for temporarily fastening the handle that actuates the catheter to the handle of the duodenoscope. Such a fastening means could include a velcro strap, a “C-clamp” and/or some kind of snap-fit component. The fastening means would allow the handle  50  to be rotated and aligned such that motion of the actuation lever could correspond with the motion of a catheter tip. The advantage of such a fastening means is that the physician can more easily operate the duodenoscope, the handle  50 , and any auxiliary equipment required for the medical procedure. The physician would be able to release the catheter handle without it dropping towards the floor and without it losing rotational alignment. 
     In another embodiment, the handle may include an ergonomically shaped exterior grip  70  as shown in  FIG. 3 . The grip  70  is rotatable around the steering mechanism such that a user can change the orientation of the grip  70  with respect to the lever arm  18  and associated steering mechanism. In use, the grip  70  is rotated so that movement of the lever arm  18  produces images that move in a desired direction on an image display. The grip  70  remains in its orientation by friction or may include a locking mechanism that allows the grip  70  to rotate when released. 
     As will be appreciated, the present invention enables the physician to always have the correct orientation between what is seen on the TV monitor and what direction to move the controls on the handle. 
     While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the scope of the invention. For example, the present invention can be used with any steerable device whose position is displayed on a screen. For example, catheters whose position is determined and displayed to a user using fluoroscopy or ultrasound can use the handle of the present invention in order to align movement of the catheter with a particular direction on the screen. It is therefore intended that the scope of the invention be determined from the following claims and equivalents thereof.