Patent Publication Number: US-2011054326-A1

Title: Direct visualization catheter

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit from U.S. Provisional Application No. 61/218,468, entitled “Direct Visualization Catheter,” filed on Jun. 19, 2009. The contents of this application are hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention is generally directed to a catheter, and more particularly, to a catheter comprising a gel for direct visualization of a target site. 
     2. Related Art 
     Endoscopic or minimally invasive surgery, sometimes referred to as small incision surgery, is generally performed by inserting one or more diagnostic or surgical instruments into a patient&#39;s body through a relatively small incision(s). Generally, the endoscopic device includes a rigid or flexible tube (referred to as a catheter), a light delivery system to illuminate the tissue under inspection, and a camera system for transmitting an image of the tissue to the surgeon. Additionally, endoscopic devices may also some times include one or more medical tools, such as scissors, forceps, biopsy device, clamp, etc., disposed at the distal end of the tube. The tool(s) is typically coupled to a handle situated at the proximal end of the catheter which permits the surgeon to operate the tool. 
     The camera system typically relays images to a monitor external to the patient so that the surgeon may directly visualize the operation of any other diagnostic or surgical instruments also inserted into the patient. As used herein, direct visualization refers to viewing an image captured by a camera. 
     In certain operative circumstances, body fluids may be present at the tissue site that may prevent the surgeon from obtaining a clear view of the instruments and/or the tissue. One such example is intra-cardiac surgery in which an operation is performed on an interior portion of the heart where a significant amount of blood may be present. Or, in other situations, the surgeon&#39;s view may be obscured by other fluids which may be introduced into the operative field as part of the procedure, such as with irrigation, aqua-dissection, etc. It is thus difficult or impossible to use prior endoscopic devices in these situations where fluids may prevent or significantly inhibit direct visualization of the tissue. 
     SUMMARY 
     In one aspect of the invention, there is provided a multi-lumen steerable endoscope, comprising: a catheter comprising: an imaging lumen; and a medium lumen; a visualization tool housed in said imaging lumen; and a gel housed in said medium lumen configured to be dispensed at least in part from said medium lumen and retracted back into said medium lumen. 
     In another aspect of the invention, there is provided a method for performing an operation using a multi-lumen steerable endoscope, comprising: inserting a catheter comprising an imaging lumen and a medium lumen into a patient&#39;s body; routing the catheter to a target site within the patient&#39;s body; dispensing a gel at the target site from the medium lumen; observing the target site using a visualization tool housed in said imaging lumen; retracting said gel back into said medium lumen after performance of the operation; and removing said catheter from said patient&#39;s body. 
     In another aspect of the invention, there is provided a catheter comprising: a medium lumen; and a gel housed in said medium lumen configured to be dispensed at least in part from said medium lumen and retracted back into said medium lumen. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative embodiments of the present invention are described herein with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of an exemplary endoscopic device in which embodiments of the present invention may be advantageously implemented; 
         FIG. 2  illustrates a simplified version of a human heart in which an endoscopic device is inserted, in accordance with an embodiment; 
         FIG. 3  illustrates a flow chart of a method for performing a surgical operation using an endoscopic device, in accordance with an embodiment; 
         FIG. 4A  provides a simplified illustration of a gel dispensed at a target site, in accordance with an embodiment; 
         FIG. 4B  provides a simplified illustration of a gel in which a tools have been inserted at a target site, in accordance with an embodiment; 
         FIG. 4C  provides a simplified illustration of a target site after retraction of a gel, in accordance with an embodiment; 
         FIG. 4D  is a simplified illustration of a gel having a support structure therein, in accordance with embodiments of the present invention; 
         FIG. 5  illustrates an endoscope that uses a pull-rod mechanism for dispensing and retracting a gel, in accordance with an embodiment; and 
         FIG. 6  illustrates a simplified version of a human heart in which a plurality of catheters are inserted, in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Due to the presence of body and/or artificially introduced fluids, certain operative procedures within a patient&#39;s body have previously precluded the use of an endoscope to directly visualize the operative procedure. Exemplary such operative procedures include those involving a patient&#39;s cardiovascular system. For example, if using an endoscope in cardiovascular surgery, the blood distributed through the cardiovascular system can cover the camera lens or be present in such quantity between the endoscopic device and the target tissue that the fluids may prohibit or greatly degrade the ability of the surgeon to directly visualize the target tissue. 
     Embodiments of the present invention are generally directed to a catheter, such as a catheter for use in the presence of body and/or artificially introduced fluids. As will be discussed in further detail below, in an embodiment, a catheter comprises a transparent gel which may be dispensed during a medical procedure or surgery (collectively and generally referred to as “surgery” herein) at a target site. This gel may displace the body fluid from the target site allowing the light source of an endoscope to illuminate the target site, thereby enabling the endoscope to have a clear view of the target site. After surgery, the gel may be retracted back into the catheter, which is then removed from the patient. As will be discussed in further detail below, the catheter in which the gel is housed may be a catheter of an endoscope that also houses a visualization tool. 
       FIG. 1  illustrates an endoscopic device, in accordance with an embodiment. As illustrated, endoscopic device  100  comprises a catheter  102  and a handle  104 . Catheter  102  may comprise a visualization lumen  112 , a tool lumen  114 , a Doppler lumen  116 , and a medium lumen  118 . Each of these lumens may extend through the length of the catheter  100 . Further, catheter  102  may, for example, have an outer diameter of 6 mm/18 French, and a cross-sectional area of 28.26 mm 2 . Additionally, catheter  102  may be a multi-lumen steerable catheter such as a catheter similar to the catheter described in U.S. Pat. No. 7,037,290 to Gardeski et al., filed on Dec. 16, 2002, which is hereby incorporated by reference in its entirety. 
     Visualization lumen  112  may be used to enable a camera and light source to extend through catheter  102 . The camera and light source extending through lumen  112  may be any type of camera and light source such as commonly used in endoscopes. For example, in an embodiment the light source and camera may be an Olympus BF-2.2 T fiber optic light source and scope having an outer diameter of 2.2 mm. Further, the use of cameras and light sources in endoscopes is well known to those of skill in the art, and as such is not described further herein. 
     Tool lumen  114  may be used to enable a tool to extend through catheter  102 . This tool may be any tool useable in endoscopic surgery, such as, for example, a suture tool, a cautery tool, a scalpel, forceps, scissors, a biopsy device, a clamp, etc. Further, in an embodiment, tool lumen  114  may have a diameter such as, for example, 2.8 mm. Doppler lumen  116  may be used to enable a Doppler device to extend through catheter  102 . Doppler devices may be used for detection of blood flow in facilitating catheter placement. The use of tools and Doppler devices in an endoscopic device are well known to those of skill in the art, and as such are not described further herein. In an embodiment, each of lumens  112 ,  114 , and  116  may have the same configuration and any type of appropriately configured tool (e.g., a visualization tool, Doppler tool, or surgical tool) may be inserted through lumens  112 ,  114 , and  116 . Accordingly, each of these lumens may also be referred to generically as a tool lumen. 
     Medium lumen  118  may be used to house a transparent gel. This transparent gel may be extended out of catheter  102  during surgery and then retracted back into catheter  102  after completion of the surgery. This transparent gel may enable light from the light source to pass through the gel to illuminate the target site, and allow camera to visualize the illuminated target site. This transparent gel may be clear in color, or in other embodiments may have a different color, such as for example, a yellowish tint color. The gel further may have low surface friction to enable gel to easily be pushed out of and retracted back into medium lumen  118 . Further, this gel may also have a sufficiently low modulus so that when extended out of lumen  118 , the gel may conform with the surface of the target site. Additionally, the gel may have sufficient tear strength to reduce the possibility of a piece of gel tearing off during the operation. Further, gel also may have self healing properties so that tools, such as surgical and visualization tools, may be inserted into gel and removed without leaving a significant witness line or other marks which may reduce the visibility through the gel. 
     In an embodiment, medium lumen  118  may have a larger diameter at the distal end  122  of catheter  102  than at the proximal end  124 , and one or more or all lumens may be collapsible at their distal ends  122  to provide additional space for allowing the gel to have a wide neck when dispensed. The proximal ends of lumens in contrast may have a fixed diameter. 
     Further, the gel may only be housed in the distal end  122  of catheter  102  (i.e., the end opposite handle  104 ) and be bonded to a tool that a surgeon may use to dispense and retract the gel from lumen  118 . For example, in an embodiment, the gel may be bonded to a push rod that a surgeon may push to dispense the gel, and then pull back to retract the gel back into lumen  118 . Or, in another embodiment, the gel may be bonded to a rod connected to a ratchet mechanism located at the proximal end  124  of endoscopic device  100 , such as on handle  104 . A surgeon may then use the ratchet mechanism to dispense the gel, and then retract the gel. In still other embodiments, the gel may be dispensed or retract through the use of a vacuum or through the use of hydrostatic pressure. Such embodiments are described further below 
     It should be noted that the number and type of lumens included in catheter  102  is exemplary, and, in other embodiment, catheter  102  may include more or less lumens. For example, in embodiments, catheter  102  may include a plurality of tool lumens each for a different tool. Or, for example, other types of devices may be used to extend through the lumens of catheter  102 . Or, in yet another embodiment, catheter  102  may include only a single lumen, such as medium lumen  118  housing the transparent gel as well as the mechanism for dispensing and retracting the gel. Such a catheter may then be used along with a separate endoscope to permit a surgeon to directly visualize a target site through gel dispensed from the catheter during an operation. 
     Additionally, in certain embodiments the catheter may be configured such that gel may be dispensed from a plurality or all of the lumens within the catheter. In other embodiments, it is not necessary to have a dedicated medium lumen. In these embodiments, a lumen may serve multiple functions to dispense/retract the gel, as well as to provide access for tools, light sources, cameras, etc. In a specific such embodiment, the catheter comprises a single lumen which serves multiple functions, including dispensing and retraction of the gel. 
     Endoscopic device  100  further comprises a handle  104  that may be used to steer the catheter  102  to the target site. Additionally, handle  104  may comprise the proximal ends  124  of lumens  112 ,  114 ,  116  to allow the passage of devices, such as a light source/camera, a Doppler device, and tools through the lumens 
     Handle  104  may comprise a mechanism for allowing a surgeon to dispense gel from the medium lumen  118  at the target site during a procedure, and then retract the gel back into the medium lumen  118 . Further descriptions of exemplary mechanisms for dispensing and retracting the gel are provided in more detail below. 
     The below described embodiment will be discussed primarily in the context of endoscopic device  100  used in endovascular intracardiac surgery to perform an operation on the right ventricle of a patient&#39;s heart. However, it should be understood that exemplary catheters in accordance with the present invention may used in other operative procedures, such as, for example, lead placement, vegetation removal, Atrial septal defect/Ventricular septal defect (ASD/VSD) closure, inspection and therapy of prosthetic valves, pericardial fluid sampling, endomyocardial bypass, etc. 
       FIG. 2  illustrates a simplified version of a human heart in which an endoscopic device is inserted for performing surgery, in accordance with an embodiment. As illustrated, heart  250  comprises four separate chambers known as the left atrium  252 , left ventricle  254 , right atrium  256  and right ventricle  258 . Ventricles  254  and  258  are separated by the ventricular septum  260 , while atria  256  and  252  are separated by atrial septum  262 . 
     Oxygen poor blood enters heart  250  through two large veins, superior vena cava  266  and inferior vena cava  274  into right atrium  256 . The blood flows from right atrium  256  into right ventricle  258  through an open tricuspid valve  264 . Meanwhile, pulmonary veins  268  empty oxygen-rich blood from the lungs (not shown) into left atrium  252 . The oxygen rich blood flows from left atrium  252  into left ventricle  254  through open mitral valve  270 . 
     When the ventricles are full, tricuspid valve  264  and mitral valve  270  shut to prevent blood from flowing backward into atria  252  and  256  during ventricular contraction. Ventricular contraction causes oxygen poor blood to flow from right ventricle  258  through pulmonary artery  272  to the lungs, where the blood is oxygenated and then returned to left atrium. Ventricular contraction also causes oxygen rich blood to leave left ventricle  254  through aorta  276  to the remainder of the body. This pattern is repeated over and over, causing blood to flow continuously to heart  250 , the lungs and the remainder of the body. 
       FIG. 3  illustrates a flow chart of method for performing a surgical operation using an endoscopic device, in accordance with an embodiment.  FIG. 3  will be discussed with reference to FIGS.  2  and  4 A- 4 C, which illustrate a simplified close up view of the target site in various stages of the method of  FIG. 3 . 
     During surgery, endoscopic device  100  may be surgical inserted through an incision in the patient&#39;s skin and extended through inferior vena cava  274  into heart  250 . As shown in  FIG. 2 , catheter  102  extends through right atrium  256  and tricuspid valve  264  such that a distal end  122  of catheter  102  is positioned in right ventricle  258 . In this example, right ventricle  258  is the target site (hereinafter referred to as target site  258 ). Catheter  102  may be routed to the target site using traditional fluoroscopy and/or auditory input from a Doppler device housed in Doppler lumen  116 . Routing an endoscopic device to a target site is well know to those of skill in the art, and as such is not described further herein. 
     Once endoscopic device  100  is positioned at the target site, the surgeon may cause the gel housed in medium lumen  118  to be dispensed at the target site  258  at block  304 . As noted above, endoscopic device  100  may use various mechanisms for dispensing the gel  402 . In one example, the gel  402  may be bonded within medium lumen  118  to a push rod that a surgeon may use to dispense and retract the gel  402 . Or, for example, a ratchet mechanism may be used for dispensing and retracting the gel  402 . In other embodiments, gel  402  may be dispensed and retracted via vacuum or hydrostatic pressure. A further description of exemplary mechanisms for dispensing gel using a push rod is provided below with reference to  FIG. 5 . 
       FIG. 4A  illustrates a simplified illustration of a gel  402  dispensed at a target site  258 , such as ventricle  258  of  FIG. 2 . Gel  402  may be optically clear and allow light to pass through it so that the target site may be illuminated by the light source and visible to the camera thus allowing the surgeon to have direct visualization of the target site  258 . Gel may further exhibits gel like properties at body temperature, such that it is deformable and may be conformed to the shape of the target site  258 . For example, during surgical operations, a surgeon may dispense gel  402  at the target site  258  such that gel  402  makes direct contact with target site  258  and displaces any body fluids  404 , such as blood from the target site  258 . 
     Gel  402  may further have properties such that it exhibits low surface friction with medium lumen  118  such that the gel  402  may easily be dispensed from and retracted into lumen  118 . Gel  402  may also have sufficient tear strength and toughness so that gel  402  maintains its integrity during surgical operations so that a portion of gel  402  does not become detached during the surgery. Gel  402  also preferably is made of a non-toxic material. Gel  402  may be formed from a number of different materials exhibiting the desired properties. In certain embodiments, gel  402  is a silicone, while in other embodiments a urethane gel may be used. 
     Additionally, in an embodiment, gel  402  may also be self-healing so that tools, such as surgical and visualization tools may be inserted into and removed from gel  402  without leaving a witness line or leaving a minimal witness line. This may be beneficial in enabling a surgeon to insert and move tools in gel  404  while not significantly impairing the visibility of the target site  258  by the visualization tool. 
     After dispensing gel  402 , a surgeon may insert a visualization tool into gel  402  at block  306 . The surgeon may use the visualization tool to observe the target site  258  during, for example, performance of the procedure. The surgeon may also dispense a surgical tool at block  308  to perform a surgical procedure.  FIG. 4B  illustrates a simplified illustration of a gel  402  dispensed at a target site  258  in which tools have been inserted, in accordance with an embodiment. As illustrated, a visualization tool  412  housed in visualization lumen  112  and a surgical tool  414  housed in tool lumen  114  may be inserted into gel  402 . As noted above, visualization tool  412  may comprise a light source and a camera, such as, for example, visualization tools commonly used in endoscopes. Further, surgical tool  414  may be any type of tool useful in performing an operation on a patient. 
     After performing the surgical operation, the surgeon may retract the gel  402  back into medium lumen  118  at block  310 .  FIG. 4C  illustrates a simplified illustration of a target site after retraction of the gel, in accordance with an embodiment. As illustrated, after retraction of the gel, the body fluid may return to the space previously occupied by gel  402 . 
     After retraction of gel  402 , the surgeon may then remove catheter  102  from the patient&#39;s body at block  312 . Catheter  102  may be removed from the patient&#39;s body using any suitable mechanism. Removal of a catheter after performance of a surgical operation is well known to those of skill in the arts, and as such is not described further herein. 
     Furthermore, in certain embodiments of the present invention, gel  402  may have a support structure disposed therein.  FIG. 4D  illustrates the use of one such support structure  450 . In this embodiment, support structure  450  comprises a mesh that is dispensed from catheter  102 . Mesh  450  may dispensed in a conical form and provides a structure for gel  402  to adhere to and to facilitate effective dispensing and retraction of the gel. Mesh  450  may be formed of metal fibers, such as nitinol. It would be appreciated that other support structures may be implemented in accordance with embodiments of the present invention and the embodiment of  FIG. 4D  is merely exemplary. 
       FIG. 5  illustrates an embodiment of endoscope  100  that uses a pull rod mechanism for dispensing and retracting the gel, in accordance with an embodiment. As illustrated, gel  402  may be include in a wider portion of medium lumen  118  located at the distal end  122  of catheter  102 . The gel  402  may be bonded to a rod  504  using any suitable means. Rod  504  may pass through lumen  118  to handle  502 . A surgeon may then push the handle  502  toward the distal end  122  of the catheter  102  to dispense the gel  402 , and pull the handle  504  in the opposite direction to retract the gel  402 . Further, handle  502  or rod  504  may include markings to help indicate whether the gel is fully dispensed or retracted. It should be noted that this is a simplified diagram provided to illustrate how a pull rod mechanism may be used to dispense and retract gel, and other components may be included in endoscopic device. 
     In another embodiments, the rod  502  and handle  504  may traverse down the center of handle  104 , and or handle  502  may be used in place of handle  104 . Further, although in this simplified diagrams, lumens  112 ,  114 , and  116  are not illustrated as connected to a handle or other device on their proximal end, it should be noted that these proximal ends may be connected to a handle or controller as appropriate for the type of tool included in the respective lumen. 
     In another embodiment, rather than using a pull-rod for dispensing and retracting gel  402 , a ratchet mechanism may be used. This ratchet mechanism may be connected to a rod, such as rod  504  bonded to gel  402  for dispensing and retracting the gel  402 . Further, this ratchet mechanism may be included at any appropriate location at the proximal end of the endoscope, such as, for example, on handle  104 . 
     The methods or dispensing and retraction of gel  402  described with reference to  FIG. 5  are merely illustrative and it would be appreciated that other methods are within the scope of the present invention. For example, in one embodiment, gel  402  may be dispensed and/or retracted using a vacuum. In such embodiments, a vacuum system may connected to the catheter to use air pressure to dispense or retract gel  402 . In other embodiments, hydrostatic pressure may be used to dispense/retract gel  402 . That its, a liquid may be used to exert push/pull forces on gel  402 . 
       FIG. 6  illustrates a simplified version of a human heart in which a catheter including a gel is inserted for performing surgery, in accordance with an embodiment. In this exemplary embodiment, three catheters  612 ,  622 , and  624  are used to perform an operation, such as a transseptal puncture in the atrial septum  262  of the patient&#39;s heart  250 . Catheter  612  may be a catheter configured to dispense and detract a transparent gel  604  to the target site, which in this case is atrial septum  262 . Catheter  612  may have a single lumen housing gel  604  and a mechanism for dispensing and retracting the gel, such as those discussed above. 
     Catheter  622  may be, for example, a catheter for an endoscope comprising a visualization tool  624 . Or, in other embodiments, catheter  612  may comprise multiple lumens, such as, for example, a lumen for housing visualization tool  624  in addition to a lumen for housing gel  604 . Catheter  612  may comprise, for example, a single lumen housing a surgical tool  614  for use in performing the operation. For example, tool  614  may be a myocardial rivet. Or, in other embodiments, catheter  622  may comprise multiple lumens housing other tools, such as, for example, forceps, etc. 
     In performing the operation, a surgeon may route each of catheters  602 ,  612 , and  622  to atrial septum  262  from the same or different access locations. Then, the surgeon may dispense gel  604  from catheter  602  using a mechanism, such as the above-discussed pull rod mechanism of  FIG. 5 . The surgeon may dispense gel  604  so that a slight pressure is applied against the atrium septum  262  by gel  604  that causes gel  604  to mold itself to the shape of atrium septum  262 . This may cause gel  604  to spread out in a direction perpendicular to the longitudinal direction of catheter  602 . 
     The surgeon may then insert visualization tool  614  from catheter  612  into gel  604  to provide the surgeon with direct visualization of the target site. Then, the surgeon may perform the operation using tool  624 . As noted above, gel  604  may have self healing properties that allow the surgeon to move tools  614  and  624  around gel  604  without significantly damaging gel  604  (e.g., without leaving significant witness lines) and impairing the visualization of the target site. 
     After completion of the surgery, the surgeon may retract tools  614  and  624  from gel  604 . Then, the surgeon may retract gel  604  back into catheter  602 . After which, the surgeon may remove catheters  602 ,  612 , and  614  from the patient&#39;s body. 
     In embodiments, the catheters, such as the catheters discussed above, may have rapid exchange capabilities. For example, in an embodiment, a plurality of catheters may be manufactured, each comprising a gel and a mechanism for dispensing the gel, such as discussed above. Each of these catheters may have a rapid exchange capability. Further, tools, such as those discussed above (e.g., a visualization tool, myocardial rivet, a Doppler tool, etc.) may be manufactured such that they are configured to work with each of the plurality of catheters. Further, the catheters may be manufactured such that these tools may be exchanged between the catheters using their rapid exchange capability. This may enable the tools to be reusable in different catheters. For example, in an embodiment, a first catheter, such as catheter  100  with rapid exchange capability may be used during a first procedure where a visualization tool, a surgical tool, and a Doppler device are inserted through lumens  112 ,  114 , and  116 . Then, after the operation one or more of these tools may be detached from the catheter, sterilized, and attached to a new catheter for subsequent use in another operation. 
     While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. All patents and publications discussed herein are incorporated in their entirety by reference thereto.