Abstract:
Guidewires and methods useable in conjunction with image guidance systems to facilitate performance of diagnostic or therapeutic tasks at locations within the bodies of human or animal subjects.

Description:
RELATED APPLICATION 
     This application is a continuation in part of U.S. patent application Ser. No. 11/116,118 entitled Methods and Devices for Performing Procedures Within the Ear, Nose, Throat and Paranasal Sinuses filed Apr. 26, 2005, which is a continuation in part of 1) U.S. patent application Ser. No. 10/829,917 entitled “Devices, Systems and Methods for Diagnosing and Treating Sinusitis and Other Disorders of the Ears, Nose and/or Throat” filed on Apr. 21, 2004, 2) U.S. patent application Ser. No. 10/912,578 entitled “Implantable Device and Methods for Delivering Drugs and Other Substances to Treat Sinusitis and Other Disorders” filed on Aug. 4, 2004, 3) U.S. patent application Ser. No. 10/944,270 entitled “Apparatus and Methods for Dilating and Modifying Ostia of Paranasal Sinuses and Other Intranasal or Paranasal Structures” filed on Sep. 17, 2004 and 4) U.S. patent application Ser. No. 11/037,548 entitled “Devices, Systems and Methods For Treating Disorders of the Ear, Nose and Throat” filed Jan. 18, 2005, the entireties of each such parent application being expressly incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to methods and devices for medical treatment and more particularly to guidewires adapted for use with electromagnetic image guidance systems and their method of manufacture and use. 
     BACKGROUND OF THE INVENTION 
     Image-guided surgery (IGS) is a technique wherein a computer is used to obtain a real-time correlation of the location of an instrument that has been inserted into a patient&#39;s body to a set of preoperatively obtained images (e.g., a CT or MRI scan) so as to superimpose the current location of the instrument on the preoperatively obtained images. In a typical IGS procedure, a digital tomographic scan (e.g., CT or MRI) of the operative field is obtained prior to surgery. A specially programmed computer is then used to convert the digital tomographic scan data into a digital map. During surgery, special instruments having sensors (e.g., electromagnetic coils that emit electromagnetic fields) mounted thereon are used to perform the procedure while the sensors send data to the computer indicating the current position of each surgical instrument. The computer correlates the data it receives from the instrument-mounted sensors with the digital map that was created from the preoperative tomographic scan. The tomographic scan images are displayed on a video monitor along with an indicator (e.g., cross hairs or an illuminated dot) showing the real time position of each surgical instrument relative to the anatomical structures shown in the scan images. In this manner, the surgeon is able to know the precise position of each sensor-equipped instrument without being able to actually view that instrument at its current location within the body. 
     Examples of commercially available electromagnetic IGS systems that have been used in ENT and sinus surgery include the ENTrak Plus™ and InstaTrak ENT™ systems available from GE Medical Systems, Salt Lake City, Utah. Other examples of electromagnetic image guidance systems that may be modified for use in accordance with the present invention include but are not limited to those available from Surgical Navigation Technologies, Inc., Louisville, Colo., Biosense-Webster, Inc., Diamond Bar, Calif. and Calypso Medical Technologies, Inc., Seattle, Wash. 
     When applied to functional endoscopic sinus surgery (FESS) the use of image guidance systems allows the surgeon to achieve more precise movement and positioning of the surgical instruments than can be achieved by viewing through an endoscope alone. This is so because a typical endoscopic image is a spatially limited, 2 dimensional, line-of-sight view. The use of image guidance systems provides a real time, 3 dimensional view of all of the anatomy surrounding the operative field, not just that which is actually visible in the spatially limited, 2 dimensional, direct line-of-sight endoscopic view. As a result, image guidance systems are frequently used during performance of FESS, especially in cases where normal anatomical landmarks are not present, in revision sinus surgeries or wherein the surgery is performed to treat disease that abuts the skull base extends into the frontal or sphenoid sinus, dehiscent lamina papyracea and/or orbital pathology. 
     Additionally, a procedure for balloon dilation of the ostia of paranasal sinuses has been developed, wherein a guidewire is advanced into a diseased paranasal sinus and a balloon catheter is then advanced over the guidewire to dilate the ostium of that paranasal sinus, thereby improving drainage from the diseased sinus (Balloon Sinuplasty™ system, Acclarent, Inc., Menlo Park, Calif.). Parent application Ser. No. 11/116,118 describes a variety of sensor equipped devices including sensor equipped guidewires that are useable in performance of the procedure using Balloon Sinuplasty™ tools under image guidance in conjunction with an IGS system. 
     There remains a need in the art for the development of improved sensor equipped instruments and devices for use in IGS procedures. 
     SUMMARY OF THE INVENTION 
     The present invention provides guidewires having sensors (e.g., electromagnetic coils that detect or emit electromagnetic energy and radiofrequency devices that emit or detect radiofrequency energy like antennas) and removable proximal hubs that interface with an IGS system. The guidewires of one embodiment of the present invention are useable in conjunction with electromagnetic IGS systems such that the IGS system may be used to track the real time position of the guidewire within the body of a human or animal subject. 
     In accordance with one embodiment of the present invention, there is provided a guidewire device for use with an image guidance surgery system. Such guidewire device generally comprises a) an elongate guidewire shaft having a proximal end and a distal end, b) a sensor located on or in said shaft, such sensor being operative to emit energy that may be used by an image guidance system for real time determination of the location of the sensor within a subject&#39;s body, c) first electrical contacts located on the shaft at or near its proximal end, d) wires extending between the sensor and the contacts and e) a connector hub member that is disposable on and removable from the guidewire shaft, such hub member having second electrical contacts that electrically couple to the first electrical contacts on the guidewire when the hub member is disposed on said guidewire shaft. In this manner, the hub member facilitates delivery of current to the sensor and the sensor emits a field which is used by the image guidance system to ascertain the position of the guidewire within the subject&#39;s body. After the guidewire has been advanced to its intended position, the hub member is removed from the guidewire, thereby allowing other devices (e.g., catheters and the like) to be advanced over the guidewire and used to perform diagnostic or therapeutic task(s). In some embodiments, the guidewire may be less than 110 centimeters in length (e.g., approximately 100 centimeters) and may be transnasally insertable to a location within the ear, nose, throat or paranasal sinus of the subject. In some embodiments, a polymer layer (e.g., heat shrunk polymer film) may be formed on a portion of the guidewire to facilitate grasping of the guidewire during use but such polymer layer may cover less than the entire length of the guidewire. 
     Further in accordance with the invention, there is provided a method for using an image guidance system to determine the location of a guidewire within the body of a human or animal subject, such method comprising the steps of: (A) inserting into the body of the subject a guidewire that has i) a distal portion, ii) a sensor positioned on or in the distal portion, ii) a proximal portion and iv) first electrical contacts located on the proximal portion, said first electrical contacts being connected to the sensor; (B) inserting the proximal portion of the guidewire into a connector hub that has second electrical contacts such that the second electrical contacts of the connector hub become electrically coupled to the first electrical contacts of the guidewire; (C) passing electrical energy through the sensor to cause the sensor to emit a field; and (D) using the image guidance system to determine the location of the field emitted by the sensor and to correlate said location to stored anatomical image data, thereby ascertaining the location of the guidewire within the body. After the guidewire has been placed in an intended position within the body, the connector hub is removed and a second device (e.g., a catheter) is advanced over the guidewire. Such second device is then used to perform a therapeutic or diagnostic task within the subject&#39;s body. 
     Further aspects, details and embodiments of the present invention will be understood by those of skill in the art upon reading the following detailed description of the invention and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a guidewire of one embodiment of the present invention being used in conjunction with an IGS system to perform a transnasal procedure. 
         FIG. 2  is a longitudinal sectional view of one embodiment of a guidewire of the present invention. 
         FIG. 2A  is a cross sectional view through line  2 A- 2 A of  FIG. 2 . 
         FIG. 2B  is a cross sectional view through line  2 B- 2 B of  FIG. 2 . 
         FIG. 2C  is a cross sectional view through line  2 C- 2 C of  FIG. 2 . 
         FIG. 3  is a side view of one embodiment of a sensor housing of the guidewire of  FIG. 2 . 
         FIG. 3  A is a perspective view of a sensor assembly comprising the sensor housing of  FIG. 3  with an electromagnetic sensor coil and related packaging mounted therein. 
         FIG. 4  is a longitudinal sectional view of a proximal hub device that is attachable to and detachable from the proximal end of a sensor-equipped guidewire of the present invention. 
         FIG. 4A  is a longitudinal sectional view of the proximal hub device of  FIG. 4  attached to the guidewire of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description, the drawings and the above-set-forth Brief Description of the Drawings are intended to describe some, but not necessarily all, examples or embodiments of the invention. The contents of this detailed description, the accompanying drawings and the above-set-forth brief descriptions of the drawings do not limit the scope of the invention or the scope of the following claims, in any way. 
     System Useable For Transnasal Image-Guided Procedures 
     With reference to  FIG. 1 , there is shown a guidewire  10  of the present invention inserted through a transnasal guide catheter  14  into the nose of a subject. A connector hub  12  of the present invention is disposed on the proximal end of the guidewire  10 . The connector hub is connected by a cable  100  to an image guidance system  16 . This image guidance system generally includes a video monitor  18  and a computer  20 . The manner in which these components of the system operate will be discussed in further detail herebelow. 
     Guidewire Device 
     The guidewire device  10 , and certain components thereof, are shown in detail in  FIGS. 2-3A . In the particular embodiment shown, the guidewire  10  comprises a flexible outer coil  49  having a core wire system  50  extending therethrough. This guidewire  10  includes a distal portion  30 , a mid-portion  32  and a proximal portion  34 . In general, the outer coil  49  is a flexible structure and the core wire system  50  serves to impart column strength (e.g., “pushability”), torquability, and regionally varying degrees of rigidity to the guidewire  10 . 
     In an embodiment suitable for certain transnasal applications, the outer coil  49  may be formed of stainless steel wire or other alloys  56  of approximately 0.005 to 0.007 inches diameter, disposed in a tight helical coil so as to form a tubular structure that has a lumen  58  (as shown in  FIG. 2B ) and has an outer diameter of approximately 0.035 inches. The core wire system  50  extends through lumen  58  of helical outer coil  49  and a sensor assembly  60  (shown in detail in  FIG. 3A ) is mounted within the distal end of lumen  58 , as explained fully herebelow. 
     The core wire system  50  comprises a distal core wire segment  50   d , a proximal core wire segment  50   p  and a transitional core wire segment  50   t . The proximal core wire segment  50   p  is affixed (e.g., soldered or otherwise attached) to the outer coil  49  at locations L ( FIG. 2 ). In this particular example, the distal core wire segment  50   d  is approximately two to approximately four centimeters in length and is formed of stainless steel wire having an outer diameter of approximately 0.006 to approximately 0.008 inches and its distal portion may optionally be swaged or compressed to a generally flattened configuration, thereby rendering that distal portion more flexible in one plane (e.g., up and down) than in the opposite plane (e.g., side to side), in accordance with techniques known in the art of guidewire manufacture. The proximal end of distal core wire segment  50   d  is round (i.e., not swaged or flattened) and is integral with the distal end of the transitional core wire segment  50   t . In this example, the transitional core wire segment  50   t  comprises a tapered region on the distal end of proximal wire segment  50   p . The proximal core wire segment  50   p  is formed of stainless steel wire having an outer diameter of approximately 0.010 to approximately 0.013 inches and the transitional core wire segment  50   t  tapers from the approximately 0.010 to approximately 0.013 inch diameter at its proximal end to the approximately 0.006 to approximately 0.008 inch diameter at its distal end where it attaches to the distal core wire segment  50   d . Since the distal core wire segment  50   d  is smaller in cross sectional dimension than the proximal core wire segment  50   d , the distal portion  30  of the guidewire  10  is more flexible than the mid-portion  32 . 
     The sensor assembly  60  is mounted within the distal portion  30  of the guidewire. The sensor assembly  60  comprises a housing  62  that is laser cut from thin walled tubing made of stainless steel or other alloy. The housing  62  is cut to form a helical side wall  42  and a cylindrical distal part  40 . An electromagnetic coil  71  ( FIG. 2A ) is affixed by adhesive (e.g., epoxy), melted polymer or a combination of these within the housing  62 , and lead wires  70  extend from the electromagnetic coil  71 , out of the proximal end of the sensor housing  62 , as seen in  FIG. 3A . After the electromagnetic coil has been placed and secured within the sensor housing  62 , an end plug  44  is inserted into the distal part  40  of the sensor housing  62 . 
     The sensor assembly  60  us then screwed into the distal end of the outer coil  49  causing the helical side wall  42  of sensor housing  62  to become frictionally engaged with adjacent convolutions of the outer coil  49 . 
     The lead wires  70   a  and  70   b  pass through the lumen  58  of outer coil  49  into the proximal portion  34  where they are connected to contacts  80   a  and  80   b  respectively. Contacts  80   a  and  80   b  comprise bands of electrically conductive material that extends around coil  49 , as seen in  FIGS. 2 and 2C . Insulators  82  (e.g., bushings formed of electrically insulating material such as PEBAX, adhesive, polyimide or a combination of these) are disposed on either side of each contact  80   a ,  80   b . A proximal seal member  88  is disposed at the proximal end of the guidewire  10  and the proximal end of the proximal core wire segment  50   p  is received within such seal member  88 . 
     The proximal portion  34  of the guidewire  10  is configured to be inserted into the connector hub  14 . The guidewire distal of the electrical contacts can be coated with parylene, Teflon or silicone. 
     Connector Hub Device 
     One possible example of the construction of connector hub  14  is shown in  FIGS. 4 and 4A . This embodiment of the connector hub  14  comprises a molded plastic housing  90  having an opening  92  in its distal end. Although not shown in the drawing, a retaining mechanism such as a twist lock Tuohy-Borst silicone valve grip mechanism can be located in opening  92 . Such a mechanism can be used to selectively grip the guidewire. The opening  92  leads to a guidewire receiving recess  94  having first and second spring electrodes  96   a ,  96   b  disposed at spaced apart locations that correspond to the linear distance between the midpoints of contacts  80   a ,  80   b  of the guidewire  10 . Wires  98  connect spring electrodes  96   a ,  96   b  to cable  100 . 
     The guidewire receiving recess  94  terminates at its proximal end in an abutment surface  101 . As seen in  FIG. 4A , the proximal portion  34  of guidewire  10  is inserted through opening  92  and is advanced into recess  94  until the proximal end of the guidewire abuts against abutment surface  101 , at which point, spring electrode  96   a  will be touching contact  80   a  and spring electrode  96   b  will be touching contact  80   b . With the guidewire so inserted within connector hub  14  and cable  100  connected to the image guidance system, electrical energy from the image guidance system  16  is delivered to the electromagnetic coil  71  mounted in the distal portion  30  of guidewire  10 . This enables real time tracking of the location of the guidewire&#39;s distal portion  30  within the subject&#39;s body. 
     After the guidewire  10  has been navigated (whether with the aid of a guide  14 ) to a specific position within the subject&#39;s body, the connector hub  14  may be removed from the proximal end of the guidewire and a device (e.g., a balloon catheter, lavage catheter, endoscope or various other working devices) may then be advanced over the guidewire. 
     In some embodiments, an outer layer  84  may be selectively disposed on a portion of the guidewire  10  to facilitate gripping and rotating of the guidewire by an operator&#39;s gloved hand. In the embodiment shown, this outer layer  84  extends over a proximal segment (e.g., approximately 15 centimeters) of the mid-portion  32  of outer coil  49 . When so positioned, the outer layer  84  will be positioned on only the part of the guidewire that is typically grasped by the operator during use. Thus, this outer layer  84  does not impart additional rigidity to other regions of the guidewire  10 . This is particularly useful in applications, such as the transnasal application shown in  FIG. 1 , where the guidewire  10  extends on an upward angle as it exits the body. In such cases, added rigidity will cause the guidewire to protrude more in the upward direction rather than curving downwardly so as to be more easily handled by the operator. 
     It is to be appreciated that the specific embodiment shown in the drawings is merely one example of how the guidewire  10  and connector hub  14  may be constructed. Many other variations are possible. For example, in some other embodiments, the outer coil  49  of the guidewire  10  may not extend over the mid-portion  32 . Rather, the mid-portion  32  may be constructed of a core wire within a cable wire tube, a polymer overlamination, a hypotube, a braided polymer tube, or a helical coil. 
     It is to be further appreciated that the invention has been described hereabove with reference to certain examples or embodiments of the invention but that various additions, deletions, alterations and modifications may be made to those examples and embodiments without departing from the intended spirit and scope of the invention. For example, any element or attribute of one embodiment or example may be incorporated into or used with another embodiment or example, unless to do so would render the embodiment or example unsuitable for its intended use. All reasonable additions, deletions, modifications and alterations are to be considered equivalents of the described examples and embodiments and are to be included within the scope of the following claims.