Abstract:
A method and device is provided for accessing a target location within a branched network. The device may be passed through the working channel of a standard endoscope and includes a three-dimensional location sensor at its distal tip and an expandable extended working channel. The device has a very thin body proximal of the distal sensor such that, once the sensor is extended outside of the working channel of the endoscope, nearly all of the working channel may be used to pass tools through the extended working channel of the device.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 61/355,115 filed Jun. 15, 2010 entitled Locatable Expandable Working Channel, which is hereby incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to catheters or elongated working channels for use in medical procedures. More particularly, the present invention relates to a locatable probe designed to be deployed through the working channel of a bronchoscope and providing an expandable pathway to a distal target. 
       BACKGROUND OF THE INVENTION 
       [0003]    Catheters or elongated working channels are a staple device in performing noninvasive medical procedure. The advantages of noninvasive procedures are numerous and include decreased risk of infection, decreased tissue damage, and shorter recovery periods. Unfortunately, the types of procedures that can be preformed utilizing noninvasive techniques is often limited by the size of the body lumen through which the procedure will be conducted and, to an equal extent, the size of the catheter or working channel inserted into the body lumen through which the tools for conducting the procedures will be passed through. 
         [0004]    Catheters or elongated working channels are often supplied in standard sizes specific to a particular medical field or application. For example, in procedures involving the lung or bronchial tree, a bronchoscope is typically employed to span from the mouth, through the trachea, to proximal locations in the primary branches of the bronchial tree. Bronchoscopes generally have within their structure a working channel through which devices may be passed to access and perform procedures within the lungs. This working channel typically has an inner diameter of 2.8 mm. Therefore, all noninvasive pulmonary procedures utilizing a bronchoscope are limited to employing only those tools and devices that can fit within a 2.8 mm working channel. 
         [0005]    Due to the size limitation of the bronchoscope&#39;s working channel, it is often necessary for a physician to pass a first tool or device through the working channel, retract the first device, pass a second device through the channel, and repeat this process several times with either the same or different devices. This method not only lengthens the procedure time but also introduces the possibility that the bronchoscope or elongated working channel through which devices are passed may migrate from their desired locations. 
         [0006]    This limited working channel diameter not only dictates the size of the tools and devices a physician can use but also the size of tissue samples that may be obtained from a patient. Again, in the case of bronchoscopes, in order to obtain a sample of tissue at a point of interest, an extended working channel is typically passed through the working channel of the bronchoscope and positioned proximate to the point of interest. The extended working channel (or “EWC”) is a catheter having an outside diameter of less than 2.8 mm. A biopsy needle is then passed through the EWC, used to extract the sample, and retracted from the channel. Because the EWC has an outside diameter of less than 2.8 mm, it follows that the inside diameter of the EWC is significantly smaller. Due to the limited diameter of the EWC, the biopsy device will necessarily be quite small. As a result the tissue sample obtained will also be very small. The limited size of the tissue samples that can be obtained in this manner, in turn, often necessitate repeating the tissue extraction and sampling process several times in order to obtain a reasonable representation of the tissue characteristics within the area of interest. 
         [0007]    In the case of bronchoscopes, the 2.8 mm diameter limitation is not dictated by the constraints and characteristics of the bronchial tree. To the contrary, the tissue forming the airways of the bronchial tree are quite elastic, distal of the cartilagenous zone. These lumens are safely, and easily expanded and capable of receiving catheters and elongated working channels of significantly greater diameters than currently used. The risk of trauma does not arise from radially stretching the airways. Rather, injury is more likely to be caused by longitudinally advancing a relatively large, less flexible device through the airways, thereby placing undue axial, rather than radial, pressure on the airways and branches. 
         [0008]    There is a need in the field for a catheter or EWC that can be initially passed through the working channel of a conventional endoscope, bronchoscope or similar device but that upon placement, may radially expand once deployed within the body lumen. Thereby providing a elongated working channel through which a physician may simultaneously pass multiple tools or devices, larger tools or devices, and extract larger tissue samples. 
         [0009]    Ideally, this EWC would also be locatable by a three-dimensional navigation system. The working channel of a bronchoscope ends at the distal end of the bronchoscope, which is also where the lens of the scope is located. The working channel allows a physician to access tissue with a tool while watching the tool through the scope. Using an EWC however, often extends the tool past the viewing range of the scope. This is especially true in the lungs where the airways narrow quickly, preventing the use of the scope in the distal airways. 
         [0010]    Three dimensional tracking technology has allowed an EWC to be safely and accurately navigated into the distal airways, well past the reach of the bronchoscope. This tracking technology typically utilizes a small location sensor, preferably providing tracking data in six degrees of freedom, at a distal tip of a probe. Suitable sensors, sensing techniques and related methods and devices are disclosed in U.S. Pat. Nos. 6,188,355; 6,226,543; 6,558,333; 6,574,498; 6,593,884; 6,615,155; 6,702,780; 6,711,429; 6,833,814; 6,974,788; and 6,996,430, all to Gilboa or Gilboa et al.; and U.S. Published Applications Pub. Nos. 2002/0193686; 2003/0074011; 2003/0216639; 2004/0249267 to either Gilboa or Gilboa et al. All of these references are incorporated herein in their entireties. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0011]    A device and method for allowing the placement of a larger biopsy tool at distal locations in a branched structure while still utilizing the working channel of a standard bronchoscope. The device includes a locatable probe that can be extended out of the working channel and navigated distally therefrom. The probe includes a lumen formed of an expandable material that essentially provides a radially expanding EWC. 
         [0012]    In certain embodiments, the radially expandable working channel or catheter may further employ an anchoring mechanism for securing a distal end of the device within a patient lumen. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    These and other aspects, features and advantages of which embodiments of the invention are capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the following drawings. 
           [0014]      FIG. 1  is perspective view of a preferred embodiment of a device according to the present invention; 
           [0015]      FIG. 2  is a perspective view of a distal end of a preferred embodiment of a device according to the present invention; and 
           [0016]      FIG. 3  is a perspective view of a preferred embodiment of A device according to the present invention with a biopsy tool being passed therethrough. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0017]    Specific embodiments of the invention will now be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements. 
         [0018]    Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
         [0019]    Referring now to  FIG. 1 , there is shown an embodiment of a device  20  of the present invention, extending through a standard bronchoscope  10 . The bronchoscope  10  is shown as having a working channel  12  and an optical lens  14 . It is understood, however, that the bronchoscope  10  shown is just an illustrative representation of a standard bronchoscope having a working channel  12  and that the present invention  20  is designed for use with any bronchoscope or endoscope. 
         [0020]    The device  20  generally includes a sensor  20 , sensor wires  24 , and a flexible sheath  30 . The sheath  30  encompasses the sensor  22  and the wires  24 . Preferably, the sheath  30  encases the sensor  22  and the wires  24  within a wall of the sheath  30 . The remaining material of the sheath forms a thin, flexible wall around an expandable lumen  32 , shown best in  FIG. 2 , which is an enlarged view of a distal end  26  of the device  20 . 
         [0021]      FIG. 3  shows the device  20  being extended from the working channel  12  of a bronchoscope  10 . As shown, once the sensor  22  exits the working channel  12 , the wires  24  and the sheath  30  are all that remain in the working channel  12 . Due to the small profile of the wires  24 , and the thin, flexible nature of the sheath  30 , nearly all of the 2.8 mm working channel lumen remains available for passing a tool, such as a biopsy tool, therethrough. 
         [0022]    In  FIG. 3  a tool  40  is shown in phantom lines passing through the lumen  32  of the device  20  of the present invention. The sheath  30  stretches to accommodate the tool  40  as the tool passes through the lumen  32 . Preferably, in order to facilitate smooth passage of the tool  40 , the sheath  30  is constructed of a biologically friendly, expandable material that is also strong as well as slippery. Non-limiting examples of acceptable materials include: polyamide, polyethylene, polyurethane, polyester, pylon, and silicone. 
         [0023]    The body of the device  20 , proximal of the sensor  22 , is contemplated as being limited to merely the wires  24 , leading to and from the sensor  22 , and the sheath  30  material. Keeping the body limited to these components reduces the profile. Additionally, however, it may be desirable to provide the device with at least some steerability. As such, the wires  24 , sheath  30 , or both may be either formed with a gentle curve, provided with a steering wire. 
         [0024]    In one embodiment, steerability is provided by using the wires  24  as steering wires. By gently pulling one wire relative to the other, the sensor  22  turns slightly in the direction of the pulled wire. The proximal ends of the wire may be fed through a prior art steering device to effect this, as long as connection is made to a navigation system. 
         [0025]    In operation, certain embodiments of the present invention may be utilized in conjunction with conventional medical endoscopes. For example, the above described embodiments may conform to an initial non-expanded outer diameter less than that of the interior diameter of the working channel of a endoscope such as, for example, a bronchoscope. The radially expandable EWC may first be passed through the working channel of the bronchoscope, optionally using said sensor to assist in navigation of said expandable EWC. The distal end of the EWC may then be anchored proximate to a point of interest within the patient. Once the EWC is secured at the point of interest, the bronchoscope may be withdrawn over the anchored EWC from the patient&#39;s airway. With the constraint of the bronchoscope&#39;s limited diameter working channel removed, the physician may proceed with expanding and/or passing the desire devices and tools through the radially expandable EWC. 
         [0026]    Alternatively, radially expandable EWCs according to the present invention may also be employed without the aid or otherwise absent a conventional endoscope. For example, a guidewire or steerable catheter may simply be navigated to the point of interest within the patient. The radially expandable EWC may then be passed over the guidewire or steerable catheter. The physician may then anchor the EWC proximate to the region of interest and proceed with expanding and/or passing the desire devices and tools through the radially expandable EWC. 
         [0027]    Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.