Patent Publication Number: US-2018049804-A1

Title: Apparatus and Methods for Ablation Efficacy

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to U.S. Prov. App. 61/321,471 filed Apr. 6, 2010, which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to catheter control systems and methods for stabilizing images of moving tissue regions such as a heart which are captured when intravascularly accessing and/or treating regions of the body. 
     BACKGROUND OF THE INVENTION 
     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. 
     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. 
     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. 
     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. 
     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. 
     Moreover, because of the uneven anatomy of tissue surfaces, imaging devices which can accommodate various anatomies as well as effectively deliver energy to these tissue regions with uneven surfaces are desirable. 
     SUMMARY OF THE INVENTION 
     A tissue-imaging and manipulation apparatus described herein which may be used for ablation by passing energy such as an electric current through the clearing fluid such that the energy passes directly to the tissue region being imaged and the electrical energy is conducted through the fluid without the need for a separate ablation probe or instrument to ablate the tissue being viewed. Details of such visual electrode ablation systems are described in further detail in U.S. patent application Ser. No. 12/118,439 filed May 9, 2008 (U.S. Pat. Pub. 2009/0030412), which is incorporated herein by reference in its entirety. Mechanisms for channeling the energy to the deeper regions of tissue or instruments which may deploy the effective position of the hood aperture beyond the surface of the hood may be utilized so that the energy can be delivered to the target tissue despite small or large irregularities in the target tissue surface and/or changes in the relative distances between the hood and the target tissue. 
     One variation is a hood assembly which defines an aperture but has a distal membrane which is relatively more rounded or, extended beyond the circumferential atraumatic contact lip or edge defined by the hood. This variation of the rounded distal membrane may be used to treat tissue surfaces with some depressions or pockets or invaginations. Alternatively, an elongated tubular or conduit features that extend from the distal membrane of the hood may also be designed, configured, or shaped such that they enter, nest, or, locate within the areas of the tissue surface with invaginations due to the mechanical resilience and/or shape of the feature. Another variation may include a hood assembly having an elongated feature and an additional fluid permeable feature, such as a screen, mesh, grating, or porous membrane through which fluid can exchange yet with limited transport in order to better limit blood from entering the hood. 
     The elongated feature may also contain a stiffening element around the aperture where the stiffening member may minimize distortion at the aperture that could potentially affect the opening area so as to prevent the energy delivered per unit time from altering during delivery. The stiffening element may comprise any number of shapes (e.g., partial or complete hoop, ring, band, etc.) and may further comprise any number of biocompatible materials (shape memory metals, polymers, any combination of materials, etc.) that provides a substantially stiffer component than the hood material member and can be utilized to predictably support the shape of the hood aperture and thereby maintain an accurate energy density during energy delivery. Prior to deployment, the stiffening member may be configured into a collapsed low-profile shape for delivery, e.g., through a sheath, with the collapsed hood but once deployed, the stiffening member can regain its pre-deformed shape. 
     Additionally and/or optionally, the elongated tubular/conduit feature can be collapsed or retracted (within the hood open area) when visualizing along tissue surfaces or treating the tissue, if so desired, such that the hood face can maintain close contact relative to the tissue. Deployment and/or retraction of the elongated feature may be accomplished by a number of different mechanisms. For example, the elongated feature may be preferentially configured due to the nature of the material or to the molding of the feature to become biased in one or both configurations. In this example, if elongated feature is retracted within the expanded hood, the introduction of the clearing fluid within the hood may push or urge the elongated feature to deploy. Additionally, retraction of the elongated feature may be accomplished by depressing the feature against a tissue surface such that the feature is biased to invaginate or deflect inwardly with respect to the rest of the hood. 
     Another variation may incorporate a fluid permeable feature such that when the interior of the hood is pressurized to create an internal positive pressure, the elongated feature may be urged to extend or deploy from the hood. Similarly, the hood interior may be de-pressurized to create an internal negative and/or reduced pressure that effectively retracts the elongated feature proximally into the open area of the hood. The elongated feature may be configured to deploy and/or retract at predetermined pressures. 
     Another variation of the hood may incorporate a relatively rigid internal support member attached to the stiffening member which may be pushed or pulled axially through the catheter to impart a force, to the stiffening member. In use, the internal support member may be selectively pushed relative to the catheter and hood to deploy the elongated feature. Similarly, the support member may be selectively pulled to retract the elongated feature. 
     In any of the variations shown and described herein, the permeable feature may be optionally incorporated over the aperture with or without the elongated features to provide additional rigidity to the hood shape while being partially pressurized with fluid for flushing/irrigating. This added rigidity may minimize distortions and deformations of the hood aperture and therefore facilitate an even energy density distribution during ablation. 
     In yet another variation, alternatively and/or additionally to the elongated feature, an electrode tipped shaft or catheter may be advanced or retracted through the catheter and hood open area to deliver energy either through the hood aperture or distal to the aperture. In yet another variation, the electrode having a slidable sheath can be advanced through the hood open area where a position of the sheath can be independently controlled relative to the electrode. By adjusting the position of sheath relative to the electrode location, the amount of exposed surface area of the electrode can be controlled to adjust the output energy density given a certain power setting to adjust the lesion formation characteristics. 
     Yet another variation of the hood may further incorporate an optional porous or fluid dispersing feature over the aperture. In this example, the porous or fluid dispersing feature may generally comprise a cap-like or domed structure which curves distally beyond the hood face in an arcuate manner. The fluid dispersing feature may define one or more (e.g., a plurality) of openings over the feature which allow for the free passage of the clearing fluid through the feature in a dispersed manner much like a shower head. The feature may be energized or charged via one or more connections, e.g., through support struts, to provide for the application of energy through the clearing fluid as the fluid is dispersed through the feature. Accordingly, the feature may be comprised of a metallic or electrically conductive material. Alternatively, the clearing fluid may be energized via an electrode within the hood interior and then pass through the dispersing feature to the underlying tissue. In other variations, the fluid dispersing feature may instead be configured as a tubular or cylindrical structure which covers the aperture and further extends distally from the hood. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a side view of one variation of a tissue imaging apparatus during deployment from a sheath or delivery catheter. 
         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. 
         FIG. 1C  shows an end view of a deployed imaging apparatus. 
         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. 
         FIGS. 3A and 3B  show examples of various visualization imagers which may be utilized within or along the imaging hood. 
         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. 
         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. 
         FIG. 6A  shows a perspective view of a hood having a flattened distal membrane that can be used to treat most relatively flat tissue surfaces. 
         FIG. 6B  shows a perspective view of a hood having a rounded distal membrane. 
         FIGS. 7A to 7D  show perspective views of various hoods having an elongated feature that extends distally from the front surface of the hood. 
         FIGS. 8A and 8B  show perspective views of hood variations having an elongated feature with an optional stiffening element and permeable feature. 
         FIGS. 9A and 9B  show perspective views of another variation of an elongated feature in deployed and retracted states. 
         FIGS. 10A and 10B  show perspective views of another variation where the open area of the hood may be pressurized or de-pressurized to deploy and retract the elongated feature. 
         FIGS. 11A and 11B  show perspective views of another variation with an internal rigid member which may be actuated to deploy or retract axially the elongated feature. 
         FIGS. 12A and 12B  show perspective views of another variation incorporating a permeable material over the aperture. 
         FIG. 13A  shows a perspective view of another variation with an elongated feature and a permeable material over the aperture. 
         FIG. 13B  shows a perspective view of another variation of an elongated feature having annular corrugations and internal feature that limits travel. 
         FIG. 13C  shows a perspective view of another variation of an elongated feature that has annular corrugations similar to  FIG. 13B  but without the internal feature. 
         FIG. 13D  shows a perspective view of another variation of an elongated feature that has annular corrugations and an internal actuation member which enables the controlled distal displacement or retraction of the elongated feature. 
         FIGS. 14A and 14B  show perspective views of various rigid members. 
         FIGS. 15A and 15B  show cross-sectional side views of a hood delivering energy to a tissue sample where the aperture is in intimate contact against the tissue surface and at a distance from an uneven tissue region. 
         FIGS. 16A and 16B  show cross-sectional side views of a hood delivering energy through an elongated feature which is retracted when positioned against a region with a relatively flat surface and a region with an uneven tissue surface. 
         FIGS. 17A to 17C  illustrate perspective views of a hood having an electrode instrument which may be advanced distally through the hood aperture. 
         FIGS. 18A to 18E  illustrate perspective views of a hood having an electrode instrument with a retractable sheath. 
         FIGS. 19A and 19B  show cross-sectional side views of an electrode instrument advanced distally of the aperture and positioned within the open area of the hood. 
         FIGS. 20A and 20B  show cross-sectional side views of an electrode instrument with the sheath advanced distally of the aperture and positioned within the open area of the hood. 
         FIGS. 21A to 21C  show variations of electrode instruments. 
         FIGS. 22A and 22B  show cross-sectional side views of a hood delivering energy through the hood aperture within a region of trabeculae which inhibits the hood from advancing further and further inhibits the energy from effectively reaching the targeted tissue. 
         FIGS. 23A and 23B  show cross-sectional side views of a hood having the elongated feature extended within the trabeculae to more effectively deliver energy to the underlying tissue region. 
         FIG. 24  shows a cross-sectional side view of an electrode instrument fitted or interdigitated between the trabeculae and to impart focused energy to the target tissue. 
         FIGS. 25A and 25B  show cross-sectional side views of an elongated feature extended distally as it nests within an invagination in the target tissue surface. 
         FIGS. 26A and 26B  show cross-sectional side views of a hood with a corrugated elongated feature extended distally to nest within a trabeculated invagination in the target tissue surface. 
         FIGS. 27A and 27B  show cross-sectional side views of a hood with a corrugated elongated feature extended distally to nest within an invagination in the target tissue surface. 
         FIGS. 28A to 28E  show cross-sectional side views of a hood having an electrode instrument which has a distal portion which is configured with a pre-determined curvature to effectively catch or hook trabeculae which may then be severed to allow for the hood to access the underlying tissue region. 
         FIG. 29  illustrates an example of how a hood having a corrugated elongated feature may maintain contact with the target tissue as the hood is translated along a curved surface. 
         FIGS. 30A to 30C  show perspective and cross-sectional side views of a hood having an internal member or ridge which limits the excursion of the corrugated surface as it is compressed within the hood open area. 
         FIGS. 31A and 31B  show side and perspective views of yet another variation where the hood may further incorporate an optional porous or fluid dispersing feature over aperture. 
         FIGS. 32A and 32B  show side and perspective views of yet another variation of a hood assembly incorporating a fluid dispersing feature where the feature may be configured as a tubular or cylindrical structure which covers the aperture and further extends distally from the hood. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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 instruments 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. Although intravascular applications are described, other extravascular approaches or applications may be utilized with the devices and methods herein. 
     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. 
     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 . Additionally, as the hood  12  functions as a barrier or membrane between the fluid in the environment surrounding the hood and the interior of the hood, the hood may comprise a non-inflatable membrane which may be configured to be self-expanding or optionally actuated. 
     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 . 
     As seen in the example of  FIGS. 2A and 2B , 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 . 
     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. 
       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. 
     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 . 
     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 instruments. 
     Moreover, aperture  42  may be aligned with catheter  16  such that any instruments (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 , instruments passed through catheter  16  may still access the underlying tissue by simply piercing through membrane  40 . 
     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 . 
     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. 
     Moreover, any of the variations described herein may be used for ablation by passing energy such as an electric current through the clearing fluid such that the energy passes directly to the tissue region being imaged and the electrical energy is conducted through the fluid without the need for a separate ablation probe or instrument to ablate the tissue being viewed. Details of such visual electrode ablation systems are described in further detail in U.S. patent application Ser. No. 12/118,439 filed May 9, 2008 (U.S. Pat. Pub. 2009/0030412), which is incorporated herein by reference in its entirety. 
     When ablating tissue within the chambers of the heart, target tissue regions that are generally inaccessible or deep (e.g., distal) to the hood  12  or which are obstructed by trabeculae or other tissue structures may receive less controlled power (or focused energy density) than tissue directly adjacent to the hood aperture. Mechanisms for channeling the energy to the deeper regions of tissue or instruments which may deploy the effective position of the hood aperture beyond the surface of the hood may be utilized so that the energy can be delivered to the target tissue despite small or large irregularities in the target tissue surface and/or changes in the relative distances between the hood and the target tissue. Furthermore, mechanisms and techniques for excising, cutting and/or disrupting tissue that covers or obstructs the deeper tissue regions in order to allow the hood to be delivered even further distal are also disclosed. 
       FIG. 6A  shows a perspective view of hood  12  having distal membrane  40  which defines the aperture  42  for comparison. The hood  12  may be used to treat most tissue surfaces which are relatively flattened or unobstructed.  FIG. 6B  shows another example in the perspective view of hood  12  having a distal membrane  50  which defines aperture  42  but also has a distal membrane  50  which is relatively more rounded or extended beyond the circumferential atraumatic contact lip or edge  52  defined by the hood  12 . This variation of the rounded distal membrane  50  may be used to treat tissue surfaces with some depressions or pockets or invaginations. 
     The hood  12  generally enables direct visualization of tissue in a blood-filled environment by maintaining a positive flow of the clearing fluid, such as saline or other suitable liquid, that may intermittently or continuously purge blood from the open area of the hood  12  through the aperture  42  at the distal membrane  40  thereby creating an optically clear visual pathway that extends to the tissue surface intimate to the front of the hood  12 . Direct apposition of the tissue to the hood distal membrane  40  may ensure good image quality and also minimize the intrusion of blood into the hood open area that could potentially degrade the clarity of the optical path. Additionally, the position of the hood  12  may be typically maintained in an orientation normal to the tissue surface relative to the catheter longitudinal axis in order to provide the most even, uniform, or least obstructed visualization field and also to prevent uneven fluid leakage from the hood aperture  42  that could also allow blood to enter the hood open area. 
     As described in further detail in U.S. patent application Ser. No. 12/118,439 (which has been incorporated by reference hereinabove), hood  12  can be utilized for direct ablation of tissue by energizing the fluid retained temporarily within the open area of the hood by one or more electrodes mounted within or along the hood to create a virtual electrode. The electrolytic clearing fluid is used as the energy conductor in order to ablate the tissue adjacent or in proximity to the aperture while also allowing direct visualization of the lesion formation. Direct visualization of the underlying tissue also ensures that the proper position, location, and proximity to structures or other lesions is well determined and/or identified prior to beginning, during, or after the ablation procedure. 
     There are several factors that can affect the efficiency and efficacy of the ablation process while utilizing such a hood structure. For example, the area of the hood aperture can be relatively constant so that the energy density is maintained during the ablation sequence/procedure. Area changes of the aperture may affect or alter the energy density and the effective power delivered which may change the lesion formation characteristics in the tissue. Additionally, the position of the one or more electrodes within the hood can impact the energy density given a specific output power and therefore can affect lesion formation. Also the distance of the hood aperture from the surface of the tissue can have an impact as well particularly if there is a sufficiently large gap, due to the potential fall-off of energy density as the current leaks out to the large blood and fluid volume surrounding the hood and ultimately directs or focuses less of the energy to the target tissue. Therefore, maintaining intimate contact with the tissue and preventing distortion of the opening are desirable parameters to control in order to ensure efficient and consistent lesion formation. 
     Furthermore, the ability of the hood  12  to accommodate irregularities in the tissue surface (e.g., recesses, voids, invaginations, etc.) and having a hood aperture maintained in relatively close proximity to the tissue surface despite changes in orientation of the overall hood structure relative to the tissue surface are also desirable in controlling the energy delivery even despite different and varying tissue surface geometries, conditions, anatomies, anomalies, and pathologies. By having a substantially curved or rounded distal membrane  50 , as shown in  FIG. 6B , can help the hood  12  to engage with varying tissue surfaces. 
     Alternatively, elongated tubular or conduit features that extend from the distal membrane of the hood may also be designed, configured, or shaped such that they enter, nest, or locate within the areas of the tissue surface with invaginations due to the mechanical resilience and/or shape of the feature. One example is shown where the aperture of the hood may be extended even farther distally from the contact lip or edge  52  to reach deeper tissue regions for more direct or intimate energy delivery.  FIG. 7A  shows an example in the perspective view of hood  12  having an elongated feature  62  that projects distally from the surface  60  of the hood  12  at a length L 1 , e.g., x1-x2 cm, and may narrow from an initial wider diameter down to a relatively smaller diameter D 1 , e.g., y1-y2 cm, which defines the aperture  64 . 
       FIG. 7B  shows a perspective view of another example where the elongated feature  66  extends even further with at a length of L 2 , e.g., z1-z2 cm, which is relatively longer than the elongated feature  62  of  FIG. 7A  to treat even deeper tissue invaginations or regions. In this example, the elongated feature  66  may narrow from an initial diameter down to a narrower diameter D 1  similarly to the diameter shown in  FIG. 7A . Another variation is shown in the perspective view of  FIG. 7C  which shows elongated feature  68  which may narrow from an initial diameter to a relatively smaller diameter D 2 , e.g., a1-a2 cm, which defines the aperture  70  in order to enter tissue regions with more closely spaced features or structures.  FIG. 7D  shows another example in the perspective view of hood  12  with an elongated feature  62  which may narrow in diameter from an initial wider diameter to the smaller diameter D 1  with an additional fluid permeable feature  72 , such as a screen, mesh, grating, or porous membrane through which fluid can exchange yet with limited transport in order to better limit blood from entering the hood  12 . 
       FIG. 8A  shows another variation in the perspective view of hood  12  with elongated feature  62  which also contains a stiffening element  80  around the aperture  64  where the stiffening member  80  may minimize distortion at the aperture that could potentially affect the opening area so as to prevent the energy delivered per unit time from altering during delivery. Stiffening element  80  may comprise any number of shapes (e.g., partial or complete hoop, ring, band, etc.) and may further comprise any number of biocompatible materials (shape memory metals, polymers, any combination of materials, etc.) that provides a substantially stiffer component than the hood material member and can be utilized to predictably support the shape of the hood aperture and thereby maintain an accurate energy density during energy delivery. Prior to deployment, stiffening member  80  may be configured into a collapsed low-profile shape for delivery, e.g., through a sheath, with the collapsed hood  12  but once deployed, the stiffening member  80  can regain its pre-deformed shape.  FIG. 8B  shows a perspective view of the hood  12  of  FIG. 8A  but with an additional fluid permeable feature  72  optionally incorporated over the aperture. 
     Additionally and/or optionally, the elongated tubular/conduit feature can be collapsed or retracted (within the hood open area) when visualizing along tissue surfaces or treating the tissue, if so desired, such that the hood face can maintain close contact relative to the tissue. As illustrated in the perspective views of  FIGS. 9A and 9B , the elongated feature  62  may be optionally deployed  82  from a retracted position within the opened hood  12  into the deployed profile shown in  FIG. 9A . The elongated feature  62  may be optionally retracted  84  proximally into the hood open area, as shown in  FIG. 9B , for facilitating contact between the distal membrane  60  and the tissue surface or for removal of the hood assembly. Deployment  82  and/or retraction  84  of the elongated feature  62  may be accomplished by a number of different mechanisms. For example, the elongated feature  62  may be preferentially configured due to the nature of the material or to the molding of the feature to become biased in one or both configurations. In this example, if elongated feature  62  is retracted within the expanded hood  12 , the introduction of the clearing fluid within the hood  12  may push or urge the elongated feature  62  to deploy. Additionally, retraction of the elongated feature  62  may be accomplished by depressing the feature  62  against a tissue surface such that the feature  62  is biased to invaginate or deflect inwardly with respect to the rest of hood  12 . 
       FIGS. 10A and 10B  show perspective views of another variation for deploying  82  and/or retracting  84  the elongated feature  62 . In this variation, the elongated feature  62  may incorporate fluid permeable feature  72  such that when the interior of the hood  12  is pressurized to create an internal positive pressure (e.g., via a depressed  92  plunger in syringe  90 , a pump, or any other pressurized fluid source) as indicated by pressure gauge  96 , the elongated feature  62  may be urged to extend or deploy  82  from the hood  12  despite some fluid leakage through permeable feature  72 . Similarly, the hood interior may be de-pressurized (e.g., by the retraction of plunger  94 ) as indicated by the decreased pressure on gauge  96  to create an internal negative and/or reduced pressure that effectively retracts  84  the elongated feature  62  proximally into the open area of the hood  12 . The elongated feature  62  may be configured to deploy and/or retract at predetermined pressures. 
       FIGS. 11A and 11B  show perspective views of another variation of hood  12  which incorporates a relatively rigid internal support member  100  attached to stiffening member  80  which may be pushed or pulled axially through catheter  16  to impart a force to the stiffening member  80 . In use, the internal support member  100  may be selectively pushed relative to the catheter  16  and hood  12  to deploy  82  elongated feature  62 . Similarly, support member  100  may be selectively pulled to retract  84  the elongated feature  62 . Alternatively, support member  100  may be actuated to one or more intermediate positions to maintain the elongated feature  62  at some partially deployed or retracted configuration. 
     In any of the variations shown and described herein, the permeable feature  72  may be optionally incorporated over the aperture with or without the elongated features to provide additional rigidity to the hood shape while being partially pressurized with fluid for flushing/irrigating. This added rigidity may minimize distortions and deformations of the hood aperture and therefore facilitate an even energy density distribution during ablation.  FIG. 12A  shows a perspective view of hood  12  having distal membrane  40  with permeable feature  72  covering the aperture.  FIG. 12B  shows a perspective view of hood  12  having the rounded or extended distal membrane  50  also having permeable feature  72  covering the aperture.  FIG. 13A  shows a perspective view of hood  12  having the elongated feature  68  also having permeable feature  72  covering the aperture. 
       FIG. 13B  shows a perspective view of another variation of hood  12  having a tapered elongated feature  110  which is comprised of annular corrugations that allow it to compress or expand in an axial direction by allowing the corrugations to roll or intussuscept within one another and compress. The annular corrugations may compress into a stable cylindrical-like structure in order to minimize kinks, folds, wrinkles or other unwanted geometries that would otherwise impede fluid flow or cause a visualization obstruction. 
     The elongated feature  110  may be tapered and may further optionally incorporate a stiffening member  80  around its aperture  70 , as previously described, to provide additional structural rigidity. A permeable feature may also be optionally incorporated as well over aperture  70 , if so desired. Additionally, an optional stiffening structure  112  (such as a ring, hoop, etc.) may be positioned within the open area of the hood  12  proximal to the elongated feature  110  and proximal to the aperture  70  to limit the degree of invagination that the elongated feature  110  collapses into the hood open area, as shown in  FIG. 13B . This may help control the “snap” or biphasic nature of the collapsing elongated feature  110  and prevent uncontrolled or unwanted movement. 
       FIG. 13C  shows a perspective view of another variation of hood  12  having the corrugated elongated feature  110  but without, the internal stiffening structure  112  which may simplify the overall design and provide the ability to store extra material within the open area of the hood  12 , especially for small hood volumes and form factors that are desirable for reaching especially small, tight, or constrained regions of target tissue.  FIG. 13D  shows a perspective view of another variation of hood  12  having the elongated feature  110  but with support member  100  attached to the stiffening member  80  to selectively retract or deploy the elongated feature  110 . 
       FIGS. 14A and 14B  show examples of support member  100  as having an elongate and flexible wire-like member  120  and the attached stiffening member where the stiffening member may be shaped as a complete annular ring  122  or as a discontinuous substantially circular ring  124 . Although illustrated as circular rings, the stiffening member may be formed of any shape or geometry as practicable. Moreover, the support member may be made from a polymer or metal and can be substantially stiff or soft but rigid enough to transmit force. 
     For comparison,  FIG. 15A  and  FIG. 15B  illustrate one example of how a hood  12  may be used along a tissue region having an uneven or invaginated surface to deliver RF energy (or any other energy) to a tissue without the use of an elongated feature. As previously described, energy may be conducted through the clearing fluid (e.g., saline) introduced through the hood and passed through the hood aperture  42  and into the underlying tissue either prior to, during, or after visualization of the tissue region. With the distal membrane  40  and aperture  42  positioned against the tissue surface T, the energy  130  may be delivered through the clearing fluid and into the tissue. As the hood  12  is moved along the tissue surface or repositioned at another location, such as an uneven invaginated tissue region  132  shown in  FIG. 15B , the delivered energy  130  may pass through the aperture  42  which may be positioned at a distance from the underlying invaginated tissue  132  potentially resulting in a reduction of energy and drop in efficiency of the ablative energy reaching the target tissue. 
     Turning now to  FIGS. 16A and 16B , an example is illustrated where the aperture  64  of the hood  12  may be maintained in intimate contact against the tissue surface T when a retracted elongated feature  62  is withdrawn into the open area of the hood when visualizing and/or treating a relatively flattened region of tissue T. The energy  130  may delivered to the tissue with maximum efficacy and efficiency due to the elongated feature  62  being able to “collapse” and invaginate (fold) within the open area of the hood  12 . The elongated feature  62  may be maintained in its collapsed configuration by maintaining the hood  12  against the tissue surface or utilizing any of the reconfiguration mechanisms described herein. 
     As the hood  12  is moved to an invaginated tissue region  132 , as shown in  FIG. 16B , elongated feature  62  may be allowed to extend from the open, area of the hood  12  and project distally at least partially or fully into the invaginated tissue region  132  to reposition its aperture  64  into intimate or direct contact against the invaginated tissue. The energy  130  may then be delivered to the tissue through aperture  64  with maximum efficacy and efficiency. 
     In yet another variation, alternatively and/or additionally to the elongated feature, an electrode tipped shaft or catheter may be advanced or retracted through the catheter  16  and hood open area to deliver energy either through the hood aperture  42  or distal to the aperture  42 .  FIGS. 17A and 17B  show perspective views of hood  12  with an electrode  142  positioned at a distal end of shaft or catheter  140  for delivering RF energy that can be advanced distally within the hood to control/adjust/alter energy delivery through the hood aperture  42 .  FIG. 17C  shows how electrode  142  may be advanced distally such that the electrode  142  is passed through aperture  42  and outside the distal membrane  40  such that energy can be delivered to tissue regions beyond the face of the hood or in order to directly contact the target tissue. 
     In yet another variation, electrode  142  having a slidable sheath  150  can be advanced through the hood open area where a position of the sheath  150  can be independently controlled relative to the electrode  142 , as shown in  FIGS. 18A to 18C . By adjusting the position of sheath  150  relative to the electrode  142  location, the amount of exposed surface area of electrode  142  can be controlled to adjust the output energy density given a certain power setting to adjust the lesion formation characteristics. Furthermore, the entire assembly can be placed in any position within the hood  12  or outside of the hood  12  such that the RF energy delivery can be customized to achieve a desired lesion shape, area and/or depth by altering the energy density exposed to the target tissue. The position of the sheath  150  relative to the electrode  142  and to aperture  42  can be adjusted proximally and distally by either controlled, indexed, and/or defined displacements of the delivery system in order to prevent an injury due to unwanted penetration into the tissue surface. 
       FIG. 18A  shows an example of how electrode  142  and shaft  140  may be advanced distally through hood  12  with sheath  150  retracted within the catheter  16 .  FIG. 18B  shows a perspective view of electrode  142  retracted proximally within the hood open area but with the sheath  150  partially advanced to control and/or focus energy delivery by covering a portion of the electrode  142  (depending on the electrode shape, design or configuration).  FIG. 18C  shows another example of electrode  142  that is advanced distally past aperture  42  but with sheath  150  partially advanced as well to control and/or focus energy delivery by covering a portion of the electrode  142 . 
       FIG. 18D  shows a perspective view of electrode  142  and sheath  150  advanced together through hood  12  and distally past aperture  42 .  FIG. 18E  illustrates electrode  142  with sheath  150  advanced beyond of the electrode  142 . By covering the electrode  142 , the energy emitted from the electrode  142  may be focused to a narrow region of target tissue, either in a tissue contact or non-contact configuration, by further passing an electrolytic fluid  154  not only through hood aperture  42  but also through sheath  150  and past electrode  142  as well. 
       FIG. 19A  illustrates a cross-sectional side view of hood  12  with electrode  142  advanced past the hood aperture  42  and in proximity with the tissue region T for delivering the energy directly to the tissue T. Even with the distal membrane  40  of hood  40  removed from contact with the tissue T, energy  130  may be delivered to the tissue.  FIG. 19B  shows another example where electrode shaft  140  and sheath  150  may be retracted proximally into the open area of the hood  12 . In this configuration, energy  130  may be delivered through the clearing fluid passed through aperture  42  and directly to the tissue T with distal membrane  40  in contact or adjacent to the tissue surface. 
       FIG. 20A  shows a side view of hood  12  in another example where electrode  142  may be advanced distally of aperture  42  and in proximity against the tissue surface T with sheath  150  at least partially covering electrode  142 . Due to the limited area of exposed electrode  142  and the close proximity to the tissue T, the energy  130  may be delivered in a more focused region to create a narrower region of ablated tissue.  FIG. 20B  shows another example with the covered electrode  142  positioned within the hood  12  while delivering the energy  130  through the aperture to the target tissue T. Due to the covered electrode and the retracted position, the delivered energy  130  may treat a larger area of tissue than that shown in  FIG. 20A . 
     In utilizing the electrode and sheath  150 , different electrode configurations may be used depending upon the desired application.  FIG. 21A  shows a cross-sectional side view of an electrode having a constant area  FIG. 21B  shows an electrode shaft  160  having an expandable tip member or members  162  initially constrained in a low-profile configuration within the sheath  150 .  FIG. 21C  shows the electrode tip  162  in a deployed configuration beyond the cover where the tip may be expanded in two or more members to increase the surface area of the exposed electrode and provide another mechanism of adjusting the delivered energy density. 
     In utilizing any of the assemblies described herein, regions of tissue to be visualized or treated may be obstructed by various anatomy such as trabeculae which may prevent the hood  12  from advancing or contacting the tissue to be visualized or treated. An example is illustrated in  FIGS. 22A and 22B  which show cross-sectional side views of a hood  12  which may deliver energy  130  to underlying tissue T which is relatively flat allowing for direct apposition of the aperture  42  against or in proximity to the tissue surface. As the hood  12  is moved across an uneven region of tissue  132  which is obstructed by trabeculae  170 , visualization and/or energy delivery may be hindered due to poor energy density or energy fall-off beyond the hood aperture  42 , as shown in  FIG. 22B . 
     Using any of the variations described herein, obstructed tissue may still be effectively treated. One example is shown in the cross-sectional side views of  FIGS. 23A and 23B . As shown, elongated feature  62  may be retracted within the hood open area to visualize and/or treat the underlying tissue T along relatively flattened areas, as shown in  FIG. 23A . However, as the hood  12  encounters, e.g., trabeculae  170  within a region of uneven tissue  132 , the elongated feature  62  may be deployed or extended to fit within the trabeculae  170  such that the aperture  64  is closer to the targeted tissue to more effectively deliver a higher energy density for more efficient and effective ablation. 
       FIG. 24  shows another example where the electrode shaft  140  and/or sheath  150  may be advanced distally past the aperture  42  and fitted or interdigitated between the trabeculae  170  to impart focused energy  130  to the target tissue. 
       FIGS. 25A and 25B  show another example where elongated feature  110  which is corrugated may be collapsed within the hood open area when placed against a relatively flat target tissue surface T. When advanced over an uneven region or tissue  132 , the corrugated elongated feature  110  may be extended distally to nest within the invagination in the target tissue surface. Due to the resiliency in the material of the elongated feature and/or by using an internal rigid member (as described above), the elongated feature  110  can fit within the pocketed feature. Even when not being able to reach the deepest recesses of the invagination, the delivered energy density can remain high due to the captured/contained volume of energized fluid which reduces energy losses to the rest of the fluid environment. The tissue can still be cooled to prevent excessive ablation and/or bubble formation by flushing the contained region with the clearing fluid at a relatively lower temperature. 
       FIGS. 26A and 26B  shows yet another example of the elongated feature  110  which may be used to treat a relatively flattened tissue region T when the feature  110  is in a collapsed configuration and then extended when encountering an uneven tissue region  132  even when obstructed, e.g., by trabeculae  170 .  FIGS. 27A and 27B  show another example where the elongated feature  110  may be fully, extended into an uneven region of tissue  132  which is particularly deep to effectively deliver the energy  130  to the underlying invaginated tissue. 
       FIG. 28A  shows a cross-sectional side-view of another variation of an electrode instrument  180  which may be advanced with an optional sheath  150  through the interior of the hood  12  and distally through the aperture  42  for advancement into an uneven tissue region  132  obstructed, e.g., with trabeculae  170 . As the electrode shaft is advanced relative to sheath  150  or hood aperture  42 , a distal region  182  of the electrode instrument may be configured to take a pre-set curve in order to effectively catch, harness, or hook the trabeculae  170 , as shown in  FIG. 28B . With the curved distal region  182  interdigitated within the trabeculae  170 , the electrode may be energized, e.g., with RF energy  184  via an RF generator source  186  such that the distal region  182  may effectively cuts or sever the trabeculae  170  or other anatomical structure in order to create sufficient space for the hood  12  to effectively enter the tissue region  132 , as shown in  FIG. 28C . In other variations, the distal region  182  may alternatively incorporate exposed sharp blade edges to enable the cutting action. 
     With the energized distal region  182 , the trabeculae  170  may be severed and the electrode  182  may be retracted proximally into the hood  12 , as shown in  FIG. 28D .  FIG. 28E  shows a cross-sectional side view of hood  12  advanced distally into intimate contact within the uneven target tissue region  132 . The exposed electrode tip of the shaft or catheter can then be energized to ablate the targeted tissue through the aperture  42   
     In yet another example of use for hood  12  having an elongated feature which is corrugated,  FIG. 29  illustrates an example of how the hood aperture  42  may be maintained along a tangential (and/or intimate) contact with the target tissue T while the hood  12  is translated along a curved surface. In a first exemplary position, indicated by position (I), elongated feature  110  may be maintained in a collapsed configuration while visualizing and/or treating the underlying tissue. As hood  12  is moved across the tissue surface T, as indicated at position (II) where the underlying tissue surface may begin to curve, elongated feature  110  can accommodate changes in the relative angle between the hood face and the target tissue surface as well as the distance to the target tissue. As the hood  12  is further translated along the varied (variable) target tissue surface T, the elongated feature  110  may further adjust automatically without necessitating that the entire hood  12  change its overall orientation in order to maintain a good physical proximity of the hood aperture  42  with the target tissue T to ensure efficient and effective ablation of the tissue by minimizing large electrolyte leaks that can also disperse ablative energy. 
       FIG. 30A  shows a perspective view of hood  12  with corrugated elongated feature  110  that may incorporate an optional internal feature or ridge  112  within the hood  12  that limits the excursion of the elongated feature  110  as it is compressed internally within the hood  12  open area.  FIGS. 30B and 30C  illustrate internal feature or ridge  112  configured in this example as a circumferential annular ring that limits the excursion of the collapsed feature  110  as it retracts proximally into hood  12 . Feature or ridge  112  can also limit the snapping or popping between deformed states that may occur as the corrugated regions fold over each other as they are compressed. 
       FIGS. 31A and 31B  show side and perspective views of yet another variation where hood  12  may further incorporate an optional porous or fluid dispersing feature over aperture  196 . In this example, the porous or fluid dispersing feature  198  may generally comprise a cap-like or domed structure which curves distally beyond the hood face in an arcuate manner. The fluid dispersing feature  198  may define one or more (e.g., a plurality) of openings  200  over the feature  198  which allow for the free passage of the clearing fluid through the feature  198  in a dispersed manner much like a shower head. The feature  198  may be energized or charged via one or more connections, e.g., through support struts  190 , to provide for the application of energy through the clearing fluid as the fluid is dispersed through the feature  198 . Accordingly, feature  198  may be comprised of a metallic or electrically conductive material. Alternatively, the clearing fluid may be energized via an electrode within the hood  12  interior and then pass through the dispersing feature  198  to the underlying tissue. 
     Hood  12  may further define a distally curved portion  194  supported, e.g., by distal support struts  192  connected to corresponding support struts  190 . With the incorporated dispersing feature  198 , the clearing fluid may be dispersed in an even manner from the hood  12  and over the underlying tissue to provide a more even distribution of energy, e.g., for ablation of the tissue. 
       FIGS. 32A and 32B  show side and perspective views of yet another variation of a hood assembly incorporating a fluid dispersing feature where the feature  210  may be configured as a tubular or cylindrical structure which covers the aperture  196  and further extends distally from hood  12 . With the dispersing feature  210  configured as a cylindrical structure, feature  210  may contact the underlying tissue along its side surfaces or within uneven anatomy to more evenly disperse the energized clearing fluid. Thus, feature  210  may define one or more openings along its side  212  or along its distal surface  214  through which the clearing fluid may disperse evenly from the hood  12 . As above, while dispersing feature  210  may be comprised of a metallic or electrically conductive material for energizing the clearing fluid directly, it may be comprised of a non-electrically conductive material for passing the clearing fluid which may already by energized by another electrode within the hood interior. 
     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.