Abstract:
A medical manipulation assembly comprises an elongated distal steerable portion with a distal working channel extending through the elongated distal steerable portion. The assembly also comprises an elongated proximal steerable portion arranged proximally of the elongated distal assembly portion. A proximal working channel extends through the elongated proximal steerable portion. The assembly also comprises a distal steering mechanism to bend the distal steerable portion in response to movement of the distal steering mechanism. The assembly also comprises a proximal steering mechanism to bend the proximal steerable portion, independently of the distal steerable portion, in response to rotational movement of the proximal steering mechanism. The assembly also comprises distal pullwire(s) extending between the elongated distal steerable portion and the distal steering mechanism and proximal pullwire(s) extending between the elongated proximal steerable portion and the proximal steering mechanism. The distal and proximal portion working channels are configured to receive a visualization instrument.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority to U.S. Prov. Pat. App. 61/078,746 filed Jul. 7, 2008, which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to catheter control systems for controlling the articulation of visualization and treatment apparatus having imaging and manipulation features for intravascularly accessing regions of the body. 
       BACKGROUND OF THE INVENTION 
       [0003]    Conventional devices for accessing and visualizing interior regions of a body lumen are known. For example, various catheter devices are typically advanced within a patient&#39;s body, e.g., intravascularly, and advanced into a desirable position within the body. Other conventional methods have utilized catheters or probes having position sensors deployed within the body lumen, such as the interior of a cardiac chamber. These types of positional sensors are typically used to determine the movement of a cardiac tissue surface or the electrical activity within the cardiac tissue. When a sufficient number of points have been sampled by the sensors, a “map” of the cardiac tissue may be generated. 
         [0004]    Another conventional device utilizes an inflatable balloon which is typically introduced intravascularly in a deflated state and then inflated against the tissue region to be examined. Imaging is typically accomplished by an optical fiber or other apparatus such as electronic chips for viewing the tissue through the membrane(s) of the inflated balloon. Moreover, the balloon must generally be inflated for imaging. Other conventional balloons utilize a cavity or depression formed at a distal end of the inflated balloon. This cavity or depression is pressed against the tissue to be examined and is flushed with a clear fluid to provide a clear pathway through the blood. 
         [0005]    However, many of the conventional catheter imaging systems lack the capability to provide therapeutic treatments or are difficult to manipulate in providing effective therapies. For instance, the treatment in a patient&#39;s heart for atrial fibrillation is generally made difficult by a number of factors, such as visualization of the target tissue, access to the target tissue, and instrument articulation and management, amongst others. 
         [0006]    Conventional catheter techniques and devices, for example such as those described in U.S. Pat. Nos. 5,895,417; 5,941,845; and 6,129,724, used on the epicardial surface of the heart may be difficult in assuring a transmural lesion or complete blockage of electrical signals. In addition, current devices may have difficulty dealing with varying thickness of tissue through which a transmural lesion is desired. 
         [0007]    Conventional accompanying imaging devices, such as fluoroscopy, are unable to detect perpendicular electrode orientation, catheter movement during the cardiac cycle, and image catheter position throughout lesion formation. The absence of real-time visualization also poses the risk of incorrect placement and ablation of structures such as sinus node tissue which can lead to fatal consequences. 
         [0008]    Moreover, because of the tortuous nature of intravascular access, devices or mechanisms at the distal end of a catheter positioned within the patient&#39;s body, e.g., within a chamber of the heart, are typically no longer aligned with the handle. Steering or manipulation of the distal end of the catheter via control or articulation mechanisms on the handle is easily disorienting to the user as manipulation of a control on the handle in a first direction may articulate the catheter distal end in an unexpected direction depending upon the resulting catheter configuration leaving the user to adjust accordingly. However, this results in reduced efficiency and longer procedure times as well as increased risks to the patient. Accordingly, there is a need for improved catheter control systems which facilitate the manipulation and articulation of a catheter. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    A tissue imaging and manipulation apparatus that may be utilized for procedures within a body lumen, such as the heart, in which visualization of the surrounding tissue is made difficult, if not impossible, by medium contained within the lumen such as blood, is described below. Generally, such a tissue imaging and manipulation apparatus comprises an optional delivery catheter or sheath through which a deployment catheter and imaging hood may be advanced for placement against or adjacent to the tissue to be imaged. 
         [0010]    The deployment catheter may define a fluid delivery lumen therethrough as well as an imaging lumen within which an optical imaging fiber or assembly may be disposed for imaging tissue. When deployed, the imaging hood may be expanded into any number of shapes, e.g., cylindrical, conical as shown, semi-spherical, etc., provided that an open area or field is defined by the imaging hood. The open area is the area within which the tissue region of interest may be imaged. The imaging hood may also define an atraumatic contact lip or edge for placement or abutment against the tissue region of interest. Moreover, the distal end of the deployment catheter or separate manipulatable catheters may be articulated through various controlling mechanisms such as push-pull wires manually or via computer control 
         [0011]    The deployment catheter may also be stabilized relative to the tissue surface through various methods. For instance, inflatable stabilizing balloons positioned along a length of the catheter may be utilized, or tissue engagement anchors may be passed through or along the deployment catheter for temporary engagement of the underlying tissue. 
         [0012]    In operation, after the imaging hood has been deployed, fluid may be pumped at a positive pressure through the fluid delivery lumen until the fluid fills the open area completely and displaces any blood from within the open area. The fluid may comprise any biocompatible fluid, e.g., saline, water, plasma, Fluorinert™, etc., which is sufficiently transparent to allow for relatively undistorted visualization through the fluid. The fluid may be pumped continuously or intermittently to allow for image capture by an optional processor which may be in communication with the assembly. 
         [0013]    In an exemplary variation for imaging tissue surfaces within a heart chamber containing blood, the tissue imaging and treatment system may generally comprise a catheter body having a lumen defined therethrough, a visualization element disposed adjacent the catheter body, the visualization element having a field of view, a transparent fluid source in fluid communication with the lumen, and a barrier or membrane extendable from the catheter body to localize, between the visualization element and the field of view, displacement of blood by transparent fluid that flows from the lumen, and an instrument translatable through the displaced blood for performing any number of treatments upon the tissue surface within the field of view. The imaging hood may be formed into any number of configurations and the imaging assembly may also be utilized with any number of therapeutic tools which may be deployed through the deployment catheter. 
         [0014]    More particularly in certain variations, the tissue visualization system may comprise components including the imaging hood, where the hood may further include a membrane having a main aperture and additional optional openings disposed over the distal end of the hood. An introducer sheath or the deployment catheter upon which the imaging hood is disposed may further comprise a steerable segment made of multiple adjacent links which are pivotably connected to one another and which may be articulated within a single plane or multiple planes. The deployment catheter itself may be comprised of a multiple lumen extrusion, such as a four-lumen catheter extrusion, which is reinforced with braided stainless steel fibers to provide structural support. The proximal end of the catheter may be coupled to a handle for manipulation and articulation of the system. 
         [0015]    To provide visualization, an imaging element such as a fiberscope or electronic imager such as a solid state camera, e.g., CCD or CMOS, may be mounted, e.g., on a shape memory wire, and positioned within or along the hood interior. A fluid reservoir and/or pump (e.g., syringe, pressurized intravenous bag, etc.) may be fluidly coupled to the proximal end of the catheter to hold the translucent fluid such as saline or contrast medium as well as for providing the pressure to inject the fluid into the imaging hood. 
         [0016]    One example of a system configured to enable direct visualization of tissue underlying the hood and optionally treat tissue, e.g., ablation, may include an ablation assembly, hood, and deployment catheter coupled to a handle having a catheter steering and locking assembly integrated along the handle. The catheter steering and locking assembly may include a steering member pivotably coupled to a locking member where the steering member may be coupled to one or more pullwires attached thereto via a retaining member, e.g., set screw, such that manipulation of the steering member articulates the steerable section and hood in a corresponding manner. The steering member may be pivotably coupled to the locking member along a point of rotation and locking mechanism which is attached to a steering plate. 
         [0017]    The catheter shaft contains at least one lumen which allows the passage of one or more pullwires that are connected to the steering member at the proximal end of the pullwire while the distal end may be terminated and anchored to the steering mechanisms along the steerable portion of the catheter. A compression coil, e.g., made of stainless steel, with a slightly larger diameter than the pullwire may be positioned about the pullwire within the handle to allow the pullwire to slide freely therethrough. 
         [0018]    In use, the steering member may be actuated, e.g., by pulling the member proximally, to articulate the steerable portion and hood in the same direction of articulation. With the steerable portion articulated to the degree desired to position the hood, the locking member may be actuated to maintain a configuration of the steerable portion and hood by preventing or inhibiting movement of the steering member thus freeing the hand or hands of the user. A steering indicator and/or locking indicator may be optionally incorporated along the handle as a reminder to the user. 
         [0019]    The handle assembly may also optionally incorporate an optical adjustment assembly which may be used to move the distal lens of a visualization instrument, such as a fiberscope, distally or proximally from the imaged tissue region, hence simulating a zoom-in and/or zoom-out optical effect. Generally, the optical adjustment assembly is able to provide zoom-in and/or zoom-out capabilities by varying the length of the assembly. By rotating an adjustment member, which is coupled to a retaining sleeve within the optical adjustment assembly, a distal shaft portion may be advanced or retracted relative to the guide shaft. The assembly may be accordingly varied in length while distally or proximally advancing the fiberscope based on the varied length of the optical adjustment assembly to control the visualized field of view. 
         [0020]    Because manipulation of the hood and steerable portion corresponds with an angle at which the handle is positioned, the handle may also serve as an orientation indicator for the hood and steerable portion once the hood has been introduced into the patient&#39;s body. This correspondence between the planes of the handle and the resulting articulation of the hood and steerable-portion may be particularly useful for efficiently controlling the hood position within the patient&#39;s body. As the catheter is usually repeatedly torqued during a procedure, keeping track of the orientation of the deflection of the hood can be difficult, if not impossible, unless fluoroscopy is used. With the handle, the angle of deflection of the hood can be predicted by the operator without the need of fluoroscopy. This is can be particularly desirable in procedures such as transseptal punctures where an accurate angle of puncture of the septal wall is desirable to avoid complications such as perforation of the aorta. 
         [0021]    Another variation of a steering handle assembly may include an assembly having a handle portion and a steering ring which may be manipulated along any number of directions relative to the housing to control the articulation of the hood. Manipulating or pulling along a portion of the steering ring causes the steerable portion and hood to move along a corresponding direction of articulation. Moreover, because of the manner in which the steering ring is positioned to encircle the handle assembly, the operator may grip the handle along any orientation and operate the handle assembly with a single hand. 
         [0022]    The handle assembly may generally comprise a ball pivot supported by pivot support enclosed within the housing. The ball pivot may support the steering ring via one or more steering ring support members, e.g., four steering ring support members, which extend radially through corresponding support member openings. Because of the ball pivot shape, the steering ring may be moved about the pivot in any number of directions. The terminal ends of one or more pullwires may be coupled the steering ring via corresponding fasteners, e.g., set screws, securing each of the pullwire termination crimps. These pullwires may extend through the pivot support housing and through a pullwire transition manifold and into a proximal end of a multi-lumen shaft, such as the catheter. The pullwires may continue distally through the catheter where they are coupled to the steerable portion of the catheter. Each of the pullwires may be optionally encased in corresponding compression coils between the transition manifold and catheter. 
         [0023]    Although multiple pullwires may be utilized depending upon the number of directions for articulation, four pullwires may be typically utilized. Each of the four pullwires may be terminated symmetrically around a circumference of the steering ring such that a balanced four-way steering of the distal portion may be accomplished, although manipulating the steering ring along various portions of its circumference may yield combinational articulation between the pullwires to result in numerous catheter configurations. Additionally, the handle assembly may further incorporate a spring mechanism as an overdrive prevention mechanism positioned between the transition manifold and ball pivot in order to prevent over-tensioning or breaking of the pullwires if the steering ring is over-deflected in a direction. 
         [0024]    The handle assembly and catheter can be consistently deflected in the same direction by which the steering ring is being deflected regardless of the orientation of the handle assembly. For example, the handle assembly may be deflected in a first direction of actuation such that the hood is deflected in a corresponding first direction of articulation. If the handle assembly, catheter, and hood are then rotated along an arbitrary direction of rotation about the longitudinal axis of the assembly, even with the entire assembly rotated, e.g., 180°, actuating the steering ring along the first direction of actuation still results in a corresponding first direction of articulation of the hood which matches the initial direction of articulation despite the rotated assembly. 
         [0025]    In yet another variation of the catheter control handle, the control assembly may be configured to articulate at least two independently deflectable portions. As with previous variations, a steering ring may encircle the housing. However, this variation further includes a proximal handle portion extending from the housing with a proximal section control for articulating the proximal steerable section. Moreover, this particular handle assembly may be used to control articulation of the hood and the distal steerable section but also used to further control articulation of the proximal steerable section. A proximal section control located along the proximal handle portion may be actuated, e.g., by rotating the control in a first and/or second direction, to articulate the proximal steerable section within a first plane and the hood may be further articulated by manipulating the steering ring such that distal steerable section moves in a corresponding direction of articulation. 
         [0026]    Additionally and/or alternatively, visual indicators positioned directly upon the hood may also be utilized in coordination with corresponding visual indicators positioned upon the handle itself. The hood may have one or more visual indicators marked upon the distal portion of the hood such that the visual image through the hood may show at least a first directional indicator along a first portion of the hood. The handle assembly may thus have one or more directional indicators located directly upon, e.g., the steering ring, which correspond spatially with the indicators positioned upon the hood or hood membrane. 
         [0027]    The catheter control systems described herein may additionally integrate any number of features and controls for facilitate procedures. These features and controls may be integrated into any of the variations described herein. One example may include features such as flow rate control, air bubble detection, ablation activation switches, built-in image sensors, etc., may be incorporated into the handle assembly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0028]      FIG. 1A  shows a side view of one variation of a tissue imaging apparatus during deployment from a sheath or delivery catheter. 
           [0029]      FIG. 1B  shows the deployed tissue imaging apparatus of  FIG. 1A  having an optionally expandable hood or sheath attached to an imaging and/or diagnostic catheter. 
           [0030]      FIG. 1C  shows an end view of a deployed imaging apparatus. 
           [0031]      FIGS. 2A and 2B  show one example of a deployed tissue imager positioned against or adjacent to the tissue to be imaged and a flow of fluid, such as saline, displacing blood from within the expandable hood. 
           [0032]      FIGS. 3A and 3B  show examples of various visualization imagers which may be utilized within or along the imaging hood. 
           [0033]      FIGS. 4A and 4B  show perspective and end views, respectively, of an imaging hood having at least one layer of a transparent elastomeric membrane over the distal opening of the hood. 
           [0034]      FIGS. 5A and 5B  show perspective and end views, respectively, of an imaging hood which includes a membrane with an aperture defined therethrough and a plurality of additional openings defined over the membrane surrounding the aperture. 
           [0035]      FIG. 6  illustrates an assembly view of another example of a visualization system configured for a controlled articulation and manipulation of the end effector. 
           [0036]      FIG. 7A  shows a side view of one example of a handle with access lumens and visualization instrumentation extending therefrom. 
           [0037]      FIG. 7B  shows a detail side view of an example of a steering and locking mechanism located upon the handle. 
           [0038]      FIGS. 8A and 8B  show side views of an example of a visualization and treatment catheter having a steerable distal end articulated by a steering member and locked into position. 
           [0039]      FIG. 9  shows a perspective exploded assembly view of an example of the catheter steering and locking assembly. 
           [0040]      FIG. 10A  shows a perspective exploded assembly view of an optional optical adjustment assembly which may be used to provide for zooming in and out of a visualization instrument, such as a fiberscope, through the catheter. 
           [0041]      FIGS. 10B and 10C  illustrate cross-sectional side views of the optical adjustment assembly showing the relative movement of the assembly to convey the visualization instrument distally and proximally to adjust visual images. 
           [0042]      FIG. 11  shows a perspective view of an optional access cannula having a stabilizing strain-relief wire for coupling to a handle. 
           [0043]      FIG. 12  shows a side view of a handle assembly positioned to lie within a first plane correspondingly aligned with a second plane defined by a deflection of the steerable distal section. 
           [0044]      FIGS. 13A and 13B  show an example where a visualization hood has been advanced intravascularly within a patient&#39;s heart with a handle positioned external to the patient and illustrates how re-orienting the handle, e.g., by 90°, results in a corresponding articulation of the plane defined by the visualization hood and distal section within the heart. 
           [0045]      FIG. 14  shows an assembly view of another variation of the handle which is configured to manipulate the steerable distal section in multiple directions by a single hand of the user. 
           [0046]      FIG. 15  shows a detail side view of the handle of  FIG. 14 . 
           [0047]      FIG. 16  illustrates a single hand of the user manipulating a multi-directional steering ring located on the handle. 
           [0048]      FIGS. 17A and 17B  show cross-sectional side views of the handle illustrating the multiple pullwires attached to the steering ring. 
           [0049]      FIGS. 18A to 18C  show side views of the handle assembly illustrating how the handle is configured to articulate and steer the visualization hood consistently in the same direction when urged by the steering ring in the same direction regardless of the handle orientation. 
           [0050]      FIG. 19  shows an assembly view of yet another variation of the handle which is configured to manipulate the steerable distal section in multiple directions as well as curve yet another steerable section located proximal to the distal section. 
           [0051]      FIGS. 20A and 20B  show side views, respectively, of the catheter control system handle. 
           [0052]      FIGS. 21A and 21B  show end views of the catheter control handle from the perspective of the catheter shaft and from the handle end, respectively. 
           [0053]      FIGS. 22A and 22B  show perspective assembly and detail views, respectively, of the visualization assembly and catheter control handle. 
           [0054]      FIG. 23A  shows a perspective view of a steerable proximal portion of the catheter actuated by a proximal section control located along the handle. 
           [0055]      FIG. 23B  shows a perspective view of the steerable distal portion of the catheter further steered by actuation of the steering ring to maneuver the visualization hood relative to the steerable proximal portion. 
           [0056]      FIG. 24  shows a perspective exploded assembly view of the catheter control handle. 
           [0057]      FIG. 25  shows a cross-sectional side view of the catheter control handle. 
           [0058]      FIG. 26  shows a cross-sectional detail side view of the catheter control handle having the pullwires in place for controlling both the distal and proximal portions. 
           [0059]      FIGS. 27A and 27B  show side views of die control handle under single-handed manipulation whether by a user&#39;s right hand or left hand, respectively. 
           [0060]      FIG. 28  shows a perspective view of the control handle having an orientation guide located on the handle for reference to the user. 
           [0061]      FIGS. 29A and 29B  show another example where a visualization hood has been advanced intravascularly within a patient&#39;s heart with the control handle positioned external to the patient and illustrates how re-orienting the handle, e.g., by 90°, results in a corresponding articulation of the plane defined by the visualization hood and distal section within the heart. 
           [0062]      FIGS. 30A and 30B  show an end view of the hood from the perspective of an imager positioned within the hood and a side view of the control handle having orientation markers on the steering ring which correspond to similar orientation marks positioned along the hood. 
           [0063]      FIG. 30C  shows a perspective view illustrating how manipulation of the steering ring in the direction of a particular marker results in a corresponding movement of the visualization hood in a direction as correlated to the marker indicated on the hood. 
           [0064]      FIG. 31  shows an assembly view of yet another variation of the control handle incorporating multiple features. 
           [0065]      FIG. 32  shows an assembly view of how an imaging system may be incorporated directly within the control handle. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0066]    A tissue-imaging and manipulation apparatus described herein is able to provide real-time images in vivo of tissue regions within a body lumen such as a heart, which is filled with blood flowing dynamically therethrough and is also able to provide intravascular tools and installments for performing various procedures upon the imaged tissue regions. Such an apparatus may be utilized for many procedures, e.g., facilitating transseptal access to the left atrium, cannulating the coronary sinus, diagnosis of valve regurgitation/stenosis, valvuloplasty, atrial appendage closure, arrhythmogenic focus ablation, among other procedures. 
         [0067]    One variation of a tissue access and imaging apparatus is shown in the detail perspective views of  FIGS. 1A to 1C . As shown in  FIG. 1A , tissue imaging and manipulation assembly  10  may be delivered intravascularly through the patient&#39;s body in a low-profile configuration via a delivery catheter or sheath  14 . In the case of treating tissue, it is generally desirable to enter or access the left atrium while minimizing trauma to the patient. To non-operatively effect such access, one conventional approach involves puncturing the intra-atrial septum from the right atrial chamber to the left atrial chamber in a procedure commonly called a transseptal procedure or septostomy. For procedures such as percutaneous valve repair and replacement, transseptal access to the left atrial chamber of the heart may allow for larger devices to be introduced into the venous system than can generally be introduced percutaneously into the arterial system. 
         [0068]    When the imaging and manipulation assembly  10  is ready to be utilized for imaging tissue, imaging hood  12  may be advanced relative to catheter  14  and deployed from a distal opening of catheter  14 , as shown by the arrow. Upon deployment, imaging hood  12  may be unconstrained to expand or open into a deployed imaging configuration, as shown in  FIG. 1B . Imaging hood  12  may be fabricated from a variety of pliable or conformable biocompatible material including but not limited to, e.g., polymeric, plastic, or woven materials. One example of a woven material is Kevlar® (E. I. du Pont de Nemours, Wilmington, Del.), which is an aramid and which can be made into thin, e.g., less than 0.001 in., materials which maintain enough integrity for such applications described herein. Moreover, the imaging hood  12  may be fabricated from a translucent or opaque material and in a variety of different colors to optimize or attenuate any reflected lighting from surrounding fluids or structures, i.e., anatomical or mechanical structures or instruments. In either case, imaging hood  12  may be fabricated into a uniform structure or a scaffold-supported structure, in which case a scaffold made of a shape memory alloy, such as Nitinol, or a spring steel, or plastic, etc., may be fabricated and covered with the polymeric, plastic, or woven material. Hence, imaging hood  12  may comprise any of a wide variety of barriers or membrane structures, as may generally be used to localize displacement of blood or the like from a selected volume of a body lumen or heart chamber. In exemplary embodiments, a volume within an inner surface  13  of imaging hood  12  will be significantly less than a volume of the hood  12  between inner surface  13  and outer surface  11 . 
         [0069]    Imaging hood  12  may be attached at interface  24  to a deployment catheter  16  which may be translated independently of deployment catheter or sheath  14 . Attachment of interface  24  may be accomplished through any number of conventional methods. Deployment catheter  16  may define a fluid delivery lumen  18  as well as an imaging lumen  20  within which an optical imaging fiber or assembly may be disposed for imaging tissue. When deployed, imaging hood  12  may expand into any number of shapes, e.g., cylindrical, conical as shown, semi-spherical, etc., provided that an open area or field  26  is defined by imaging hood  12 . The open area  26  is the area within which the tissue region of interest may be imaged. Imaging hood  12  may also define an atraumatic contact lip or edge  22  for placement or abutment against the tissue region of interest. Moreover, the diameter of imaging hood  12  at its maximum fully deployed diameter, e.g., at contact lip or edge  22 , is typically greater relative to a diameter of the deployment catheter  16  (although a diameter of contact lip or edge  22  may be made to have a smaller or equal diameter of deployment catheter  16 ). For instance, the contact edge diameter may range anywhere from 1 to 5 times (or even greater, as practicable) a diameter of deployment catheter  16 .  FIG. 1C  shows an end view of the imaging hood  12  in its deployed configuration. Also shown are the contact lip or edge  22  and fluid delivery lumen  18  and imaging lumen  20 . 
         [0070]    As seen in the example of  FIGS. 2A and 2D , deployment catheter  16  may be manipulated to position deployed imaging hood  12  against or near the underlying tissue region of interest to be imaged, in this example a portion of annulus A of mitral valve MV within the left atrial chamber. As the surrounding blood  30  flows around imaging hood  12  and within open area  26  defined within imaging hood  12 , as seen in  FIG. 2A , the underlying annulus A is obstructed by the opaque blood  30  and is difficult to view through the imaging lumen  20 . The translucent fluid  28 , such as saline, may then be pumped through fluid delivery lumen  18 , intermittently or continuously, until the blood  30  is at least partially, and preferably completely, displaced from within open area  26  by fluid  28 , as shown in  FIG. 2B . 
         [0071]    Although contact edge  22  need not directly contact the underlying tissue, it is at least preferably brought into close proximity to the tissue such that the flow of clear fluid  28  from open area  26  may be maintained to inhibit significant backflow of blood  30  back into open area  26 . Contact edge  22  may also be made of a soft elastomeric material such as certain soft grades of silicone or polyurethane, as typically known, to help contact edge  22  conform to an uneven or rough underlying anatomical tissue surface. Once the blood  30  has been displaced from imaging hood  12 , an image may then be viewed of the underlying tissue through the clear fluid  30 . This image may then be recorded or available for real-time viewing for performing a therapeutic procedure. The positive flow of fluid  28  may be maintained continuously to provide for clear viewing of the underlying tissue. Alternatively, the fluid  28  may be pumped temporarily or sporadically only until a clear view of the tissue is available to be imaged and recorded, at which point the fluid flow  28  may cease and blood  30  may be allowed to seep or flow back into imaging hood  12 . This process may be repeated a number of times at the same tissue region or at multiple tissue regions. 
         [0072]      FIG. 3A  shows a partial cross-sectional view of an example where one or more optical fiber bundles  32  may be positioned within the catheter and within imaging hood  12  to provide direct in-line imaging of the open area within hood  12 .  FIG. 3B  shows another example where an imaging element  34  (e.g., CCD or CMOS electronic imager) may be placed along an interior surface of imaging hood  12  to provide imaging of the open area such that the imaging element  34  is off-axis relative to a longitudinal axis of the hood  12 , as described in further detail below. The off-axis position of element  34  may provide for direct visualization and uninhibited access by instruments from the catheter to the underlying tissue during treatment. 
         [0073]    In utilizing the imaging hood  12  in any one of the procedures described herein, the hood  12  may have an open field which is uncovered and clear to provide direct tissue contact between the hood interior and the underlying tissue to effect any number of treatments upon the tissue, as described above. Yet in additional variations, imaging hood  12  may utilize other configurations. An additional variation of the imaging hood  12  is shown in the perspective and end views, respectively, of  FIGS. 4A and 4B , where imaging hood  12  includes at least one layer of a transparent elastomeric membrane  40  over the distal opening of hood  12 . An aperture  42  having a diameter which is less than a diameter of the outer lip of imaging hood  12  may be defined over the center of membrane  40  where a longitudinal axis of the hood intersects the membrane such that the interior of hood  12  remains open and in fluid communication with the environment external to hood  12 . Furthermore, aperture  42  may be sized, e.g., between 1 to 2 mm or more in diameter and membrane  40  can be made from any number of transparent elastomers such as silicone, polyurethane, latex, etc. such that contacted tissue may also be visualized through membrane  40  as well as through aperture  42 . 
         [0074]    Aperture  42  may function generally as a restricting passageway to reduce the rate of fluid out-flow from the hood  12  when the interior of the hood  12  is infused with the clear fluid through which underlying tissue regions may be visualized. Aside from restricting out-flow of clear fluid from within hood  12 , aperture  42  may also restrict external surrounding fluids from entering hood  12  too rapidly. The reduction in the rate of fluid out-flow from the hood and blood in-flow into the hood may improve visualization conditions as hood  12  may be more readily filled with transparent fluid rather than being filled by opaque blood which may obstruct direct visualization by the visualization installments. 
         [0075]    Moreover, aperture  42  may be aligned with catheter  16  such that any installments (e.g., piercing instruments, guidewires, tissue engagers, etc.) that are advanced into the hood interior may directly access the underlying tissue uninhibited or unrestricted for treatment through aperture  42 . In other variations wherein aperture  42  may not be aligned with catheter  16 , installments passed through catheter  16  may still access the underlying tissue by simply piercing through membrane  40 . 
         [0076]    In an additional variation,  FIGS. 5A and 5B  show perspective and end views, respectively, of imaging hood  12  which includes membrane  40  with aperture  42  defined therethrough, as described above. This variation includes a plurality of additional openings  44  defined over membrane  40  surrounding aperture  42 . Additional openings  44  may be uniformly sized, e.g., each less than 1 mm in diameter, to allow for the out-flow of the translucent fluid therethrough when in contact against the tissue surface. Moreover, although openings  44  are illustrated as uniform in size, the openings may be varied in size and their placement may also be non-uniform or random over membrane  40  rather than uniformly positioned about aperture  42  in  FIG. 5B . Furthermore, there are eight openings  44  shown in the figures although fewer than eight or more than eight openings  44  may also be utilized over membrane  40 . 
         [0077]    Additional details of tissue imaging and manipulation systems and methods which may be utilized with apparatus and methods described herein are further described, for example, in U.S. patent application Ser. No. 11/259,498 filed Oct. 25, 2005 (U.S. Pat. Pub. 2006/0184048 A1), which is incorporated herein by reference in its entirety. 
         [0078]    In utilizing the devices and methods above, various procedures may be accomplished. One example of such a procedure is crossing a tissue region such as in a transseptal procedure where a septal wall is pierced and traversed, e.g., crossing from a right atrial chamber to a left atrial chamber in a heart of a subject. Generally, in piercing and traversing a septal wall, the visualization and treatment devices described herein may be utilized for visualizing the tissue region to be pierced as well as monitoring the piercing and access through the tissue. Details of transseptal visualization catheters and methods for transseptal access which may be utilized with the apparatus and methods described herein are described in U.S. patent application Ser. No. 11/763,399 filed Jun. 14, 2007 (U.S. Pat. Pub. 2007/0293724 A1), which is incorporated herein by reference in its entirety. Additionally, details of tissue visualization and manipulation catheter which may be utilized with apparatus and methods described herein are described in U.S. patent application Ser. No. 11/259,498 filed Oct. 25, 2005 (U.S. Pat. Pub. 2006/0184048 A1), which is incorporated herein by reference in its entirety. 
         [0079]      FIG. 6  illustrates one example of a system configured to enable direct visualization of tissue underlying hood  12  and optionally tissue treatment, e.g., ablation. As shown in ablation assembly  50 , hood  12  and deployment catheter  16  are coupled to handle  52 , as previously described. Fluid reservoir  56 , shown in this example as a saline-filled bag reservoir, may be attached through handle  52  to provide the clearing fluid and/or ablation medium. An optional access cannula  54  is also illustrated attached to handle  52  and may be used in one variation as an access lumen for flushing or clearing a working channel through handle  52  and catheter  16  where such a working channel may be used to introduce and advance any number of instruments for tissue treatment, e.g., an access needle which may be advanced into handle  52  and into or through hood  12 . An optical imaging assembly  58  coupled to an imaging element positioned within or adjacent to hood  12  may extend proximally through handle  52  and be coupled to imaging processor assembly  60  (which may also optionally include a light source) for processing the images detected within hood  12 . Assembly may also be coupled to a video receiving assembly  62  for receiving images from the optical imaging assembly  58 . The video receiving assembly  62  may in turn be coupled to video processor assembly  64  which may process the detected images within hood  12  for display upon video display  68 . 
         [0080]      FIGS. 7A and 7B  show a side view of a variation of the catheter control handle assembly and a detail side view of the handle  52  having a catheter steering and locking assembly  70  integrated along the handle  52 . As shown, handle  52  may have several access channels defined through which allow for communication for any number of instruments into and/or through the catheter  16  and hood  12 . For instance, a fluid catheter  86  may be positioned at least partially through fluid channel  88  within handle  52 . The optical imaging assembly  58 , e.g., a fiberscope or CCD or CMOS imaging assembly, maybe positioned through support shaft  94  and support shaft interface  96  which enters handle  52 . In the case where a fiberscope is utilized, the fiberscope shaft  82  may be passed through an optional optical adjustment assembly  84 , as described in further detail below. Another working channel  80  may be further defined through handle  52  to allow for entry and passage of yet another instrument, e.g., a piercing needle, ablation probe, etc. 
         [0081]    Also shown is catheter steering and locking assembly  70  integrated along the handle  52  having a steering member  72  pivotably coupled to a locking member  74 . Steering member  72  may be coupled to one or more pullwires  78  attached thereto via retaining member  92 , e.g., set screw, such that manipulation of the steering member articulates the steerable section and hood in a corresponding manner. Steering member  72  may be pivotably coupled to locking member  74  along a point of rotation and locking mechanism  76  which is attached to a steering plate  90 . 
         [0082]    The catheter shaft contains at least one lumen which allows the passage of one or more pullwires that are connected to the steering member  72  at the proximal end of the pullwire while the distal end may be terminated and anchored to the steering mechanisms along the steerable portion  100  of the catheter  16 . Details of steering mechanisms and steerable sections of the visualization catheter, which may be utilized with apparatus and methods described herein are described in U.S. patent application Ser. No. 12/108,812 filed Apr. 24, 2008 and Ser. No. 12/117,655 filed May 8, 2008, each of which is incorporated herein by reference in its entirety. The one or more pullwires can be made from metal such as stainless steel or nitinol. A compression coil, e.g., made of stainless steel, with a slightly larger diameter than the pullwire may be positioned about the pullwire within the handle  52  to allow the pullwire to slide freely therethrough. The ends of the compression coil may be glue jointed to the proximal end to the catheter body and the distal end to the side wall of the shaft. Alternatively, the pullwire may be passed through a hypo tube made of stainless steel and be anchored at the distal side wall of the catheter  16 . 
         [0083]    In use, steering member  72  may be actuated, e.g., by pulling the member proximally, to articulate the steerable portion  100  and hood  12  in the same direction of articulation  102 , as shown in the side view of  FIG. 8A . With the steerable portion  100  articulated to the degree desired to position hood  12 , locking member  74  may be actuated, e.g., in the direction of locking  104 , to maintain a configuration of steerable portion  100  and hood  12  by preventing or inhibiting movement of steering member  72 , as shown in the side view of  FIG. 8B , thus freeing the hand or hands of the user. A steering indicator  106  and/or locking indicator  108  may be optionally incorporated along handle  52  as a reminder to the user. 
         [0084]      FIG. 9  illustrates a perspective view of an exploded steering and locking assembly. As shown, the locking member  74  may define an opening  112  which is keyed to locking mechanism  76 , e.g., lock hex nut, such that the locking mechanism  76  rotates when locking member  74  is rotated. Locking mechanism  76  may also pass through an opening  114  defined along the steering member  72  as well as through an opening  116  defined through the steering plate  90  such that a terminal end of the locking mechanism  76  is coupled to lock bolt  118 . Once the one or more pullwires, which may be secured within pullwire passage  120  defined through the steering member  72  by set screw  92 , is pulled to a desired degree by steering member  72 , locking member  74  may be rotated about axis of rotation  110  to drive locking mechanism  76  into the lock bolt  118  to compress the steering member  72  between the steering plate  90  and the locking member  74 . Hence, steering member  72  is locked in its current position when locking member  74  is applied thereby holding the steerable section in its desired configuration. 
         [0085]    As previously mentioned, the handle assembly may also optionally incorporate an optical adjustment assembly  84 , as shown in the perspective exploded assembly view of  FIG. 10A . The optical adjustment assembly  84  may be used to move the distal lens of a visualization instrument, such as a fiberscope, distally or proximally from the imaged tissue region, hence simulating a zoom-in and/or zoom-out optical effect. Generally, the optical adjustment assembly  84  is able to provide zoom-in and/or zoom-out capabilities by varying the length of the assembly. As depicted in the cross-sectional side views of  FIGS. 10B  and IOC, an adjustment member  130  houses guide shaft  134  which extends proximally through receiving channel  132  of adjustment member  130  and is retained within by a retaining lip  136 . The proximally extending sliding shaft portion  144  of a second shaft is positioned slidably within guide shaft  134  while the distally extending distal shaft portion  142  of this second shaft is positioned within a sleeve opening  152  of retaining sleeve  150 , which is also positioned within adjustment member  130 . This second shaft further comprises a threaded guide  146  along a portion of its outer surface which is configured to engage rotatably with the inner surface of sleeve opening  152 , which is also threaded in a complementary manner. 
         [0086]    With the shafts assembled, one or more fasteners  158 , e.g., set screw, may be used to secure adjustment member  130  to retaining sleeve  150  through fastener opening  156  defined through member  130  and fastener interface  154  defined along retaining sleeve  150 . Distally extending distal shaft portion  142  may further define connector interface  148  for coupling to a retaining luer connector  160  while guide shaft  134  may also define a connector interface  138  for coupling to a luer connector  140 . In use, the shaft of a visualization instrument such as a fiberscope may be positioned through and secured to the assembly  84  by one or more of the connectors, e.g., luer connector  160 . By rotating adjustment member  130 , which is coupled to retaining sleeve  150 , distal shaft portion  142  may be advanced or retracted relative to guide shaft  134  via the threaded engagement between threaded guide  146  and sleeve opening  152 . The assembly  84  may be accordingly varied in length while distally or proximally advancing the fiberscope based on the varied length of the optical adjustment assembly  84  to control the visualized field of view. 
         [0087]    Also previously mentioned above, the optical imaging assembly  58  may be optionally positioned through a support shaft  94  and support shaft interface  96  which enters handle  52 , as shown in the perspective view of  FIG. 11 . Support shaft  94  may be longitudinally reinforced to protect the optical fiber used by the visualization catheter from buckling or breaking. To maintain a position of shaft  94  relative to the handle into which the shaft  94  extends, shaft  94  may incorporate a strain relief wire  162  which protrudes from the distal end of shaft  94  at an angle for temporarily locking within a wire channel  164 , as shown above in  FIG. 7B . Once wire  162  has been engaged within channel  164  within the handle, shaft  94  may provide stability to the fiberscope shaft. The wire  162  can be made from stainless steel or nitinol and have a thickness between, e.g., 0.050″ to 0.100″. 
         [0088]    Because manipulation of the hood  12  and steerable portion corresponds with an angle at which the handle is positioned, handle  52  may also serve as an orientation indicator for the hood  12  and steerable portion once the hood  12  has been introduced into the patient&#39;s body. As shown in the side view of  FIG. 12 , the handle  52  may define a plane A. Articulation of hood  12  and the steerable portion may thus also define a plane A′ which corresponds planarly to the plane A defined by the handle  52 . This correspondence between the planes A, A′ of the handle  52  and the resulting articulation of the hood  12  and steerable portion may be particularly useful for efficiently controlling the hood position within the patient&#39;s body. As the catheter  16  is usually repeatedly torqued during a procedure, keeping track of the orientation of the deflection of the hood  12  can be difficult, if not impossible, unless fluoroscopy is used. With the handle  52 , the angle of deflection of the hood  12  can be predicted by the operator without the need of fluoroscopy. This is can be particularly desirable in procedures such as transseptal punctures where an accurate angle of puncture of the septal wall is desirable to avoid complications such as perforation of the aorta. 
         [0089]    An example of how this feature may be utilized is shown in the illustrations of  FIGS. 13A and 13B , which show a hood positioned within the right atrium of a heart H while coupled to handle  52  positioned external to the body. Handle  52  may be seen as being positioned along plane A while hood  12  and the distal portion of catheter  16  is positioned within corresponding plane A′. As handle  52  is rotated, e.g., at 90°, about its longitudinal axis in a direction of rotation  170  such that handle  52  then lies within a different plane B, hood  12  and the distal steerable portion may also rotate, e.g., at 90°, within the right atrium in a corresponding direction of rotation  170 ′ such that the hood and catheter then define a corresponding different plane B′. Thus, by merely articulating the handle  52  external to the body in a specified direction, the user may adjust or desirably position or re-position the hood within the body in a known direction without having to utilize additional catheter positioning mechanisms. 
         [0090]      FIG. 14  shows an assembly view of another variation of a steering handle assembly  180  which enables a user to steer the visualization hood  12  along at least four or more degrees of freedom relative to a longitudinal axis of the catheter  16 .  FIG. 15  shows a side view of the handle assembly  180  illustrating handle portion  182  and steering ring  184  which may be manipulated along any number of directions relative to housing  186  to control the articulation of the hood  12 . As shown in  FIG. 16 , manipulating or pulling along a portion of steering ring  184 , e.g., along a direction of actuation  192 , causes steerable portion  100  and hood  12  to move along a corresponding direction of articulation  194 . Moreover, because of die manner in which steering ring  184  is positioned to encircle the handle assembly  180 , the operator may grip the handle  180  along any orientation and operate the handle assembly  180  with a single hand  190 . For instance, the operator may manipulate the steering ring with the thumb and/or index finger while insertion length of the catheter  16  can also be simultaneously controlled by the same hand  190  by pulling or pushing the handle assembly  180  to translate the entire catheter  16 . 
         [0091]    As shown in the cross-sectional side views of  FIGS. 17A and 17B , handle assembly  180  may generally comprise a ball pivot  200  supported by pivot support  202  enclosed within housing  186 . Ball pivot  200  may support the steering ring  184  via one or more steering ring support members  204 ,  206 , e.g., four steering ring support members, which extend radially through corresponding support member openings  208 ,  210 . Because of the ball pivot  200  shape, steering ring  184  may be moved about pivot  200  in any number of directions. The terminal ends of one or more pullwires  220 ,  222  may be coupled steering ring  184  via corresponding fasteners  212 ,  214 , e.g., set screws, securing each of the pullwire termination crimps  216 ,  218 . These pullwires  220 ,  222  may extend through pivot support housing  224  which defines receiving channel  226 , which supports pivot support  202 , and through pullwire transition manifold  228  and into a proximal end of a multi-lumen shaft  234 , such as catheter  16 . The pullwires may continue distally through catheter  16  where they are coupled to the steerable portion of catheter  16 . Each of the pullwires may be optionally encased in corresponding compression coils  230 ,  232  between the transition manifold  228  and catheter. 
         [0092]    Although multiple pullwires may be utilized depending upon the number of directions for articulation, four pullwires may be typically utilized. Each of the four pullwires may be terminated symmetrically around a circumference of steering ring  184  such that a balanced four-way steering of the distal portion may be accomplished, although manipulating the steering ring  184  along various portions of its circumference may yield combinational articulation between the pullwires to result in numerous catheter configurations. Additionally, the handle assembly may further incorporate a spring mechanism  236  as an overdrive prevention mechanism, as shown in  FIG. 17B . Spring mechanism  236  may be positioned between the transition manifold  228  and ball pivot  200  in order to prevent over-tensioning or breaking of the pullwires if the steering ring  184  is over-deflected in a direction. 
         [0093]      FIGS. 18A to 18C  illustrate side views of the handle assembly  180  and catheter  16  to show how the hood  12  can be consistently deflected in the same direction by which the steering ring  184  is being deflected regardless of the orientation of the handle assembly  180 . For example, handle assembly  180  may be deflected in a direction of actuation  240  such that hood  12  is deflected in a corresponding direction of articulation  242 . A first side indicator X of handle  180  and a second opposing side indicator Y of handle  180  are shown to indicate a first position of handle  180  and the corresponding first side indicator X′ of hood  12  and corresponding second opposing side indicator Y′ of hood  12  are likewise shown to indicate a first position of hood  12 . The handle assembly  180 , catheter  16 , and hood  12  are then rotated along an arbitrary direction of rotation  244  about longitudinal axis  246  of the assembly such that the handle positional indicators X, Y and the hood positional indicators X′, Y′ are now positioned in opposite locations. Even with the entire assembly rotated, e.g., 180°, actuating the steering ring  184  along the direction of actuation  248  still results in a corresponding direction of articulation  250  of hood  12  which matches the initial direction of articulation  242  despite the rotated assembly. Regardless of the angle by which the operator subsequently rotates the catheter  16  about the longitudinal axis  246 , the operator can still be certain that deflecting the steering ring  184  in a particular direction will steer the distal end of the catheter in the same direction. This removes the need for the operator to memorize the original position of the catheter or how much the catheter has been torqued in order to gauge the orientation of the deflected end when the catheter is inserted into the patient. 
         [0094]    In yet another variation of the catheter control handle,  FIG. 19  shows an assembly view of steering handle assembly  260  which is configured to articulate a catheter  16  having at least two independently deflectable portions, e.g., a proximal steerable section  262  adapted to articulate within a single plane relative to a longitudinal axis of the catheter and a distal steerable section  264  adapted to articulate within one or more planes relative to a longitudinal axis of the proximal steerable section  262 . Utilizing such catheter steering may be particularly advantageous for tissue treatment, e.g., ablation, in the left atrium of the heart as such adaptability in steering may impart additional accuracy and efficiency to steer the imaging and ablation hood  12  around complex anatomical structures, such as the pulmonary vein ostium. Examples of such steerable catheters are shown and described in further detail in U.S. patent application Ser. No. 12/108,812 filed Apr. 24, 2008 (U.S. Pat. Pub. 2008/0275300 A1) and Ser. No. 12/117,655 filed May 8, 2008 (U.S. Pat. Pub. 2008/0281293 A1), each of which is incorporated herein by reference in its entirety. 
         [0095]    Moreover, this handle variation as well as any of the other handle variations herein may incorporate any of the features described in each of the variations, as practicable. For instance, this particular variation may also utilize the optical adjustment assembly, locking mechanisms, etc. in combination if so desired. 
         [0096]      FIGS. 20A and 20B  show side views of the steering handle assembly  260  with the catheter  16  having proximal steerable section  262  and distal steerable section  264  extending from distal handle portion  274 . As with previous variations, a steering ring  270  may encircle housing  272 . However, this variation further includes a proximal handle portion  276  extending from housing  272  with a proximal section control  278  for articulating proximal steerable section  262 .  FIGS. 21A and 21B  show end views of the control handle  260  from the perspective of the catheter shaft  16  and from the handle end, respectively. As shown, steering ring  270  may be supported by a number of steering ring support members  280 ,  282 ,  284 ,  286  which extend from housing  272  through corresponding support member openings  288 ,  290 ,  282 ,  294 .  FIGS. 22A and 22B  show additional perspective assembly and detail views, respectively, of the visualization assembly and steering handle assembly  260 . 
         [0097]    As previously described for other variations, this particular handle assembly  260  may be used to control articulation of the hood  12  and the distal steerable section  264  but also used to further control articulation of the proximal steerable section  262 . As shown in the perspective view of  FIG. 23A , proximal section control  278  may be actuated, e.g., by rotating the control  278  in a first direction  300 , to articulate the proximal steerable section  262  within a first plane, e.g., to retroflex hood  12  and distal steerable section  264  in a corresponding direction of articulation  302 . Hood  12  may be further articulated by manipulating steering ring  270 , e.g., in a direction of actuation  304 , such that distal steerable section  264  moves in a corresponding direction of articulation  306 , as shown in  FIG. 23B . In one variation, proximal steerable section  262  may be configured to articulate via proximal section control  278  within a single plane while distal steerable section  264  may be configured to articulate in at least four directions, as above. However, both the proximal section control  278  and the steering ring  270  can be manipulated in varying degrees to steer the respective steerable sections to varying curvatures as desired by the operator. 
         [0098]      FIG. 24  shows a perspective exploded assembly view of the handle assembly  260  while  FIG. 25  shows a cross-sectional side view of the same handle assembled. As shown, a ball pivot  310  having a pivot support  312  may be supported within a proximal portion of distal handle portion  274 . One or more steering ring support members  314  may extend through respective openings defined through housing  272  to support the circumferentially encircling steering ring  270 . As above, a pullwire transition manifold  316  may be positioned proximal to the catheter  16  entrance. 
         [0099]    A guide shaft  322  may be positioned at least partially through proximal handle portion  276  while maintained in position by retaining lip  324 . A sliding shaft portion  328  may be positioned slidably within guide shaft  322  while a distal shaft portion  326  may extend distally through housing  272 . A pullwire retaining member  318  haying a pullwire termination crimp  320  may be positioned along a distal end of distal shaft portion  326  such that as distal shaft portion  326  is translated distally and/or proximally according to the manipulation of section control  278 , the pullwire for the proximal steerable section  262  may be accordingly pulled or pushed. The distal shaft portion  326  may further have a threaded guide  330  which is engaged to a threaded inner surface of retaining sleeve  332 , which is secured to section control  278 . Thus, as control  278  is rotated, retaining sleeve  332  is also rotated thereby urging distal shaft portion  326  and sliding shaft portion  328  to move accordingly via the engagement with threaded guide  330 . A further access lumen  334  is illustrated as extending through the handle assembly  260 . 
         [0100]    As further illustrated in the cross-sectional side view of  FIG. 26 , the one or more proximal steerable section pullwire  342  is shown as extending from catheter  16  and extending through transition manifold  316  and terminated at pullwire retaining member  318 . Additionally, one or more distal steerable section pullwires  338 ,  340  are also shown to emerge from catheter  16 , through one or more corresponding compression coils  336 , and through transition manifold  316  to terminate at corresponding pullwire termination crimps  348 ,  350 , which may be secured to steering ring  270  via fasteners  344 ,  346 , e.g., set screws. The distal ends these pullwires, e.g., at least four pullwires, can be anchored to the inner walls of the distal steerable section  264 . At both the proximal as well as the distal ends, the pullwires may be separated, e.g., by 90°, such that the four-way steerable section is able to be steered symmetrically in at least four directions. 
         [0101]    The ends of the compression coils  336  may be glue jointed to the proximal end to the catheter body  16  and distally into the transition manifold  316 . Alternatively, the pullwires may also be passed through hypodermic tubes and anchored at the distal side wall of the catheter shaft  16  and the transition manifold  316 . Moreover, the pullwires may be made from materials such as stainless steel or nitinol and flexible thin wall compression coils, such as stainless steel coils, may be further slid over each pullwire along the catheter shaft  16 . 
         [0102]    Because of the design of the handle assembly  260  and the accessibility of the steering ring  270  to the user, the user may utilize a single hand to operate the handle assembly  260  to control and manipulate the catheter  16  and hood  12  configuration and position within the patient&#39;s body. Moreover, the operator may utilize either their right hand  360 , e.g., by gripping handle portion  276 , or their left hand  362 , e.g., by gripping distal handle portion  274 , as shown respectively in  FIGS. 27A and 27B . 
         [0103]    As previously described, because the catheter  16  and hood  12  may be repeatedly torqued and repositioned within the patient&#39;s body during a procedure, keeping track of the orientation of the deflection of the hood  12  can be difficult, if not impossible, unless fluoroscopy is used. As the handle assembly  260  provides an indication, as described herein, as to which direction the catheter and hood may be configured based upon the handle orientation, an orientation guide  372  may be imprinted directly upon the handle  274 , as shown in detail view  370  of  FIG. 28 . The plane within which the orientation guide  372  lies may be configured to be parallel to the plane within which the proximal steerable section  262  articulates when section control  278  is manipulated such that the operator may be able to predict how the catheter  16  will configure when manipulated. 
         [0104]    As similarly described above,  FIGS. 29A and 29B  illustrate a hood positioned within the right atrium of a heart H while coupled to handle assembly  260  positioned external to the body. Handle assembly  260  may be seen as being positioned along plane A while hood  12  and the distal portion of catheter  16  is positioned within corresponding plane A′. As handle assembly  260  is rotated, e.g., at 90°, about its longitudinal axis in a direction of rotation  380  such that handle assembly  260  then lies within a different plane B, hood  12  and the distal steerable portion may also rotate, e.g., at 90°, within the right atrium in a corresponding direction of rotation  380 ′ such that the hood and catheter then define a corresponding different plane B′. Thus, by merely articulating the handle assembly  260  external to the body in a specified direction, the user may adjust or desirably position or re-position the hood within the body in a known direction without having to utilize additional catheter positioning mechanisms. 
         [0105]    Additionally and/or alternatively, visual indicators positioned directly upon the hood  12  may also be utilized in coordination with corresponding visual indicators positioned upon the handle itself. The hood  12  may have one or more visual indicators marked upon the distal portion of the hood such that the visual image  390  through the hood may show at least a first directional indicator  392 ′ along a first portion of the hood, as shown in  FIG. 30A . In this example, a second directional indicator  394 ′ and yet a third corresponding third indicator  396 ′ may be positioned about a circumference of the hood or hood membrane to represent any number of directions. Handle assembly  260  may thus have one or more directional indicators located directly upon, e.g., steering ring  270 , which correspond spatially with the indicators positioned upon the hood or hood membrane, as shown in  FIG. 30B . For instance, first directional indicator  392 ′ on the hood may correspond spatially with first directional indicator  392  on steering ring  270 , second directional indicator  394  on the hood may correspond spatially with second directional indicator  394 ′ on steering ring  270 , third directional indicator  396  on the hood may correspond with third directional indicator  396 ′ on steering ring  270 , and so on. Although three directional indicators are shown in this example, fewer than three or more than three may be utilized. Moreover, the location and positioning of the indicators may also be varied, as desired. 
         [0106]    In use, the directional indicators as viewed through the hood correspond to the direction the hood may move when the steering ring  270  is deflected along the position where the corresponding indicator is located. Thus, deflecting steering ring  270  in direction of actuation  398 , e.g., along directional indicator  394 , may articulate distal steerable section  264  and hood  12  in a corresponding direction of articulation  400  along the directional indicator  394 ′ shown on the hood or hood membrane, as shown in  FIG. 30C . This removes complexity in steering the hood  12 , e.g., when the hood  12  is in a retroflexed position, where directions are reversed with respect to the operator. 
         [0107]    The catheter control systems described herein may additionally integrate any number of features and controls for facilitate procedures. These features and controls may be integrated into any of the variations described herein.  FIG. 31  shows one example where features such as flow rate control, air bubble detection, ablation activation switches, built-in image sensors, etc., may be incorporated into the handle assembly. 
         [0108]    As shown on handle  52 , a flow control  410  switch may be incorporated which may optionally have a high-flow position  412 , a no-flow position  414 , and an optional suction position  416  to control the inflow and/or outflow of the visualization and/or ablation fluid. One or more fluid reservoirs, e.g., a room temperature purging fluid reservoir  422  and/or a chilled purging fluid reservoir  424 , may be fluidly coupled to a processing unit  418  which may control various parameters, e.g., valves, inflow, suction, RF ablation energy generation, bubble detection, etc. Processing unit  418  may also incorporate a pump  420 , e.g., peristaltic pump, which may pump or urge the fluids from the reservoir through one or more coupling lines into and/or out from handle  52 . Processing unit  418  may also be electrically coupled to handle  52  and may also be able to process, display and store several data, including total amount of saline used for the entire procedure, power and duration of ablation, impedance of tissue in contact-with hood, rate of flow of saline, temperature of saline, and time of detection of air bubbles during the procedure. 
         [0109]    In the event that handle  52  is used to suction or evacuate fluids out from the body, an additional evacuation reservoir  426  may also be fluidly coupled to handle  52 . Additionally, one or more hemostasis valves  428  may also be integrated directly upon handle  52 . Moreover, an imaging sensor  430  which may also incorporate a light source, e.g., LEDs, and power supply, may additionally be integrated directly into handle  52 . A video cable may be connected to the proximal end of the handle  52  and can be directly plugged into any standard video display monitors (such as ones accepting S-Video, DVI, VGA, RCA inputs), rather than utilizing a separate video processing unit. 
         [0110]    As processing unit  418  may incorporate processors for detecting various physiological parameters, one or more detection indicators  432 , e.g., for bubble detection, and/or ablation actuation switch  434  may be integrated directly upon the handle  52  as an indicator to the operator. If air bubbles are detected in the irrigation channel, the detection indicator  432  may be activated to alert the operator of air bubbles. A soft alarm may also be triggered to further alert the operator. Additionally, with an ablation actuation switch  434  located directly upon handle  52 , the operator may be able to instantaneously activate or stop ablation energy from being delivered to the target tissue by depressing switch  434  rather than reaching for a separate ablation generator. Details for tissue ablation under direct visualization and detecting various parameters such as bubble formation are also shown and described in further detail in U.S. patent application Ser. No. 12/118,439 filed May 9, 2008 (U.S. Pat. Pub. 2009/0030412 A1 ), which is incorporated herein by reference in its entirety. 
         [0111]    Another example of an integrated handle is shown illustratively in  FIG. 32 . In this example, handle  274  may incorporate an imaging system directly into the handle. As illustrated, the images captured by the imager  440  positioned within or along hood  12  may be focused onto an electronic imaging sensor  444 , e.g., CMOS sensor, positioned within handle  274 . Imaging sensor  444  may deliver the images directly to the video processor. A light source  448 , e.g., LED light source, may also be placed within the handle  274  to deliver light through, e.g., an optical fiber  442  positioned within hood  12 , to illuminate the tissue region to be visualized. At the terminal end of the fiber bundle, a focus lens  446 , e.g., a combination of spherical lenses, may be positioned proximal to the fiber bundle. An alternative may utilize a GRIN lens which may be used as a simple one piece element which is chromatically aberration corrected and polarization preserved to allow for more design flexibility. Moreover, a GRIN lens is typically more economical than the spherical lenses. 
         [0112]    The applications of the disclosed invention discussed above are not limited to certain treatments or regions of the body, but may include any number of other applications as well. Modification of the above-described methods and devices for carrying out the invention, and variations of aspects of the invention that are obvious to those of skill in the arts are intended to be within the scope of this disclosure. Moreover, various combinations of aspects between examples are also contemplated and are considered to be within the scope of this disclosure as well.