Complex shape steerable tissue visualization and manipulation catheter

Complex steerable catheter visualization and tissue manipulation systems and their methods of use are disclosed herein. The deployment catheter is articulated using various steering mechanisms. Tissue visualization is accomplished from the visualization hood at the distal end of the deployment catheter, the hood having an ability to expand and other features to facilitate visualization and articulation at the tissue surface.

FIELD OF THE INVENTION

The present invention relates generally to catheters having imaging and manipulation features for intravascularly accessing regions of the body.

BACKGROUND OF THE INVENTION

Conventional devices for accessing and visualizing interior regions of a body lumen are known. For example, ultrasound devices have been used to produce images from within a body in vivo. Ultrasound has been used both with and without contrast agents, which typically enhance ultrasound-derived images.

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, such imaging balloons have many inherent disadvantages. For instance, such balloons generally require that the balloon be inflated to a relatively large size which may undesirably displace surrounding tissue and interfere with fine positioning of the imaging system against the tissue. Moreover, the working area created by such inflatable balloons are generally cramped and limited in size. Furthermore, inflated balloons may be susceptible to pressure changes in the surrounding fluid. For example, if the environment surrounding the inflated balloon undergoes pressure changes, e.g., during systolic and diastolic pressure cycles in a beating heart, the constant pressure change may affect the inflated balloon volume and its positioning to produce unsteady or undesirable conditions for optimal tissue imaging.

Accordingly, these types of imaging modalities are generally unable to provide desirable images useful for sufficient diagnosis and therapy of the endoluminal structure, due in part to factors such as dynamic forces generated by the natural movement of the heart. Moreover, anatomic structures within the body can occlude or obstruct the image acquisition process. Also, the presence and movement of opaque bodily fluids such as blood generally make in vivo imaging of tissue regions within the heart difficult.

Other external imaging modalities are also conventionally utilized. For example, computed tomography (CT) and magnetic resonance imaging (MRI) are typical modalities which are widely used to obtain images of body lumens such as the interior chambers of the heart. However, such imaging modalities fail to provide real-time imaging for intra-operative therapeutic procedures. Fluoroscopic imaging, for instance, is widely used to identify anatomic landmarks within the heart and other regions of the body. However, fluoroscopy fails to provide an accurate image of the tissue quality or surface and also fails to provide for instrumentation for performing tissue manipulation or other therapeutic procedures upon the visualized tissue regions. In addition, fluoroscopy provides a shadow of the intervening tissue onto a plate or sensor when it may be desirable to view the intraluminal surface of the tissue to diagnose pathologies or to perform some form of therapy on it.

Moreover, many of the conventional 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'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. No. 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. Without real-time visualization, it is difficult to reposition devices to another area that requires transmural lesion ablation. The absence of real-time visualization also poses the risk of incorrect placement and ablation of critical structures such as sinus node tissue which can lead to fatal consequences.

BRIEF SUMMARY OF THE INVENTION

A tissue imaging system which is able to provide real-time in vivo access to and images of tissue regions within body lumens such as the heart through opaque media such as blood and which also provides instruments for therapeutic procedures is provided by the invention.

The tissue-imaging apparatus relates to embodiments of a device and method 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 through it. Such an apparatus may be utilized for many procedures, e.g., mitral valvuloplasty, left atrial appendage closure, arrhythmia ablation (such as treatment for atrial fibrillation), transseptal access and patent foramen ovale closure among other procedures. Further details of such a visualization catheter and methods of use are shown and described in U.S. Pat. Pub. 2006/0184048 A1, which is incorporated herein by reference in its entirety.

Generally, the embodiments of a tissue imaging and manipulation device depicted in the present invention meet the challenge and solve the problem of accessing regions of the body which are typically difficult to access. The design and control of the catheter shaft and the distal tip of the device as disclosed here provide a device uniquely capable of accessing a region such as the human heart, which is a region not only difficult to access, but which also has continuous blood flow. The blood flow provides a barrier to visualizing the local tissue, which in turn makes any manipulation at the local tissue nearly impossible. The unique elements that form the catheter shaft and the distal tip of the device, including the separate control of the shaft and tip and several optional modes of manipulation of either or both, provide for a device adaptable to addressing the challenges inherent in intravascular access and manipulation of heart tissue, and for accomplishing a procedure in any other difficult-to-access region in the body which is bathed in a medium that interferes with visualization.

Blood is continuously flowing through the heart at all times, and as such presents a challenge to direct visualization and subsequent manipulation of heart tissue. The tissue imaging and manipulation apparatus can comprise a 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. The deployment catheter can have a fluid delivery lumen through it as well as an imaging lumen within which an optical imaging fiber or electronic imaging assembly may be disposed for imaging tissue. The distal tip of the device is an articulatable tip connected to the catheter shaft, when deployed, the imaging hood within the articulatable tip 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 of the articulatable tip 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 surface in the region of interest. The distal end of the deployment catheter or separate manipulatable catheters within a delivery sheath may be articulated through various controlling mechanisms such as push-pull wires manually or via computer control.

The visualization catheter may also have one or more membranes or layers of a polymeric material which covers at least a portion of the open area. The membrane or layer may be an extension of the deployed hood or it may be a separate structure. In either case, the membrane or layer may define at least one opening which allows for fluid communication between the visualization hood and the fluid environment within which the catheter is immersed.

In operation, after the imaging hood (at the articulatable tip) has been deployed, fluid may be pumped at a positive pressure through the fluid delivery lumen (within the catheter) until the fluid fills the open area completely and displaces any blood from within the open area. When the hood and membrane or layer is pressed against the tissue region to be visualized or treated, the contact between the one or more openings and the tissue surface may help to retain the clear fluid within the hood for visualization. Moreover, the membrane or layer may help to retain the fluid within the hood while also minimizing any fluid leakage therefrom. Additionally, the one or more openings may also provide for direct access to the underlying tissue region to be treated by any number of tools or instruments positioned within the hood at the articulatable tip.

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.

The imaging hood may be deployed into an expanded shape and retracted within a catheter utilizing various mechanisms. Moreover, an imaging element, such as a CCD/CMOS imaging camera, may be positioned distally or proximally of the imaging hood when collapsed into its low-profile configuration. Such a configuration may reduce or eliminate friction during deployment and retraction as well as increase the available space within the catheter not only for the imaging unit but also for the hood.

In further controlling the flow of the purging fluid within the hood, various measures may be taken in configuring the assembly to allow for the infusion and controlled retention of the clearing fluid into the hood. By controlling the infusion and retention of the clearing fluid, the introduction of the clearing fluid into the patient body may be limited and the clarity of the imaging of the underlying tissue through the fluid within the hood may be maintained for relatively longer periods of time by inhibiting, delaying, or preventing the infusion of surrounding blood into the viewing field.

Accordingly, there is provided a device for visualization and manipulation of difficult-to-reach tissue surfaces in a region of a body having a continuous interfering blood flow comprising a steerable catheter shaft having controls for steering of the shaft in multiple planes. The steering of the catheter and/or sheath may be separately controlled during a procedure so that a proximal steerable section of a catheter shaft can be steered to a target region without manipulation of the distal steerable section. Upon arrival at the target region, slight adjustments and steering of the hood may be articulated (and/or independently) to address the tissue surface or otherwise contact or approach a tissue surface.

The tasks performed by the articulatable hood utilize movement of the catheter shaft, but the movements of the hood and the shaft can be independent in function and control. For example, in order for the hood to contact the tissue surface to flush the region in preparation for imaging, or for making contact with and manipulating the tissue (e.g., forming a lesion around a pulmonary ostium and the like), the catheter shaft may be moved and directed or re-directed to position the hood, then once the catheter shaft has placed the hood in a desirable position, further articulation and control of the hood for cutting or lesion formation or the like can occur. For example, the hood can be articulated to contact the tissue surface and form a suitable seal in order to flush the surface with saline to visualize the tissue at the surface. The hood may have a conforming lip that can be used to make contact with the tissue surface to facilitate any of these tasks or manipulations. At the point where the hood is negotiating its position at the tissue surface, any subsequent adjustments that may need to be made to the positioning of the shaft can be made independently of the movement of the hood, although, where catheter shaft adjustment can facilitate the hood's position relative to the tissue surface, the two control mechanisms can work in concert with each other.

The distal articulatable hood can comprise one or more articulatable units along the hood that are adapted to distal control and that allow the hood to conform to the tissue surface. The articulatable units can comprise multiple steerable leaflets inside a cone-like hood. An articulatable unit can comprise a steerable hood. It may also comprise control members within the hood that allow the practitioner to manipulate the lip that surrounds the hood and the like. The distal articulatable hood can comprise a conforming lip that can be passively steered to contact the tissue surface.

The device can further comprise two or more variations in durometer along the catheter shaft. For example, where there is at least one variation in durometer along the catheter shaft, the variation in durometer can comprise a region of increased flexibility distal to a region of relatively reduced flexibility, so that the distal most end is more flexible and manipulatable.

Where the catheter shaft comprises locking units, the shaft can further comprise an outer sheath to smooth out links in the catheter shaft in the region of the shaft having the locking units.

The catheter shaft can be multi-lumen and comprise multiple pull wires, each pull wire having its own separate access lumen within the catheter shaft. In addition, the device can have a fixed bent sheath over a portion of the catheter shaft to limit the movement of the shaft where the sheath is positioned and define a fixed angle of direction of the shaft at the fixed bend.

A tissue visualization unit adapted to visualizing accessed tissue can be positioned within the articulatable tip or hood. A tissue manipulation unit adapted to manipulating accessed tissue can likewise be positioned within the articulatable tip. A device can have both such units, for optimally imaging and manipulating in the body during a procedure in real-time.

The invention is also a system for intravascularly accessing difficult to access target tissue in a region of the body having continuous interfering blood flow. The system employs a device adapted to visualization and manipulation of the accessed target tissue as just described. The device for the system may have a catheter capable of flushing the target tissue surface at the distal tip so that visualization and manipulation at the surface can occur once the tip is in contact with the tissue surface, and both a unit for visualizing the tissue surface and manipulating tissue at the tissue surface positioned within the articulatable tip. Alternatively, the system can be just for visualization of the tissue surface, in which case it will only have the visualization mechanism.

Also contemplated are methods of visualizing or manipulating difficult-to-access target tissue in a region of a body having continuous interfering blood flow. One method comprises introducing into a main artery in a patient a device described herein having the steerable catheter component and the distal attached articulatable tip component. The controls for the catheter shaft may include pull wires, locking units and variations in durometer of the shaft, etc. The articulatable hood is expandable upon arrival of the device at a target region in a body, and the hood is capable of expansion to a greater diameter than the catheter shaft.

Further refinements to the steering and control of the proximal steerable section of the catheter can be accomplished a number of ways. The catheter shaft may have a multi-lumen extrusion through which pullwires can be placed for controlling the shaft using keyhole lumens to refine the articulation of the steerable segment of the catheter. Accordingly, using these elements, the proximal steerable section is able to articulate within multiple planes relative to a longitudinal axis of the catheter.

The proximal steerable section can be configured using a steering guide that travels along a steering actuator. The steering guide is a rigid member and the steering actuator can slide along it to affect a transition of the steerable segment. This embodiment can further comprise pullwires that travel with the steering guide.

Another configuration of the apparatus that facilitates complex manipulation of both the steerable segment and the distal segment (including the hood) is a push steering mechanism in which a hinged bar aligns with the base of the distal segment and connects to the base of a region in the steerable segment that also connects to a slidable sheath located more proximally. The hinged bars control movement of the hood by creating a curve in the steerable segment that directs push control to the hood. The hinged bar guides and limits the movement of the steerable section in order to direct the position of the distal hood towards a target region. In this way the distal steerable section is adapted to articulate within one or more planes relative to a longitudinal axis of the proximal steerable section.

The embodiments directed towards complex steering, manipulation and control of the steerable sections can include that the proximal and distal steerable sections each comprise a plurality of serially aligned links which are selected from pin links, bump links, ring links, one-way links, and four-way links, etc. In addition, the proximal and distal steerable sections can each comprise a durometer different from one another. In yet another embodiment, the proximal section can comprise a steerable retro-flexing introducer sheath that directs the distal steerable section to articulate within one or more planes relative to a longitudinal axis of the proximal steerable section.

Another variation is directed towards optimized and complicated visualization of the target tissue using the visualization hood. The distal steerable section can comprise an expandable visualization member, which can be balloon expandable. Imaging elements can reside within the expanded visualization member. The expandable imaging member can be compressed for delivery in the catheter and then expanded upon release from the distal end of the catheter.

The distal steerable section can comprise an expandable anchoring member and an ablation optical source, positioned distal of an expandable visualization member. The ablation optical source can be placed in the visualization member for ablating local tissue. The anchoring member can serve to anchor the distal end at the target region so that the ablation can be directed to specific target locations. Yet another embodiment includes that the distal steerable section comprising an infrared endoscope.

The proximal and distal sections can be controlled by a handle at the proximal end of the catheter for driving the proximal and distal steering segments, and for supporting a variety of tools. The tools can be selected from a syringe, a fiberscope, a needle, valves for irrigation port, imaging elements, and valves for passing tools, for example. Pullwires can be connected to a steering lever on the handle for providing tension through the pullwires to the steerable sections of the catheter. For example, a lever on the handle can be turned to provide tension on the pullwires, which in turn controls the movement of the proximal steerable section or the distal steerable section.

Also included are methods of accessing difficult-to-reach target tissue in a region of a body having continuous interfering blood flow by articulating the proximal steerable section within multiple planes relative to a longitudinal axis of the catheter guided by keyhole lumens, and articulating the distal steerable section within one or more planes relative to a longitudinal axis of the proximal steerable section. Accordingly, the distal hood can contact difficult to reach target tissue, for example, using complex curves generated with the proximal steerable segment so that the distal segment (the hood) can contact the target tissue perpendicularly, thus providing optimum contact of the hood with the tissue. Visualizing the target tissue within an open area through the transparent fluid can be accomplished if the visualization hood is flushed with saline or other clear fluid so that the blood is cleared providing an unobstructed visualization at the region. Processes such as ablation, or marking can occur using the distal hood of at least a portion of the target tissue within the open area that has been cleared of blood.

DETAILED DESCRIPTION OF THE INVENTION

The tissue-imaging and manipulation apparatus of the invention is able to provide real-time images in vivo of tissue regions within a body lumen such as a heart, which are filled with blood flowing dynamically through the region. The apparatus 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 (such as for treating atrial fibrulation), among other procedures. Disclosure and information regarding tissue visualization catheters generally which can be applied to the invention are shown and described in further detail in commonly owned U.S. patent application Ser. No. 11/259,498 filed Oct. 25, 2005, and published as U.S. Pat. Pub. 2006/0184048, which is incorporated herein by reference in its entirety. The basic apparatus for visualizing and manipulating tissue upon intravascular access to the target region are depicted inFIGS. 1 to 10. The specific details that permit specific access to difficult-to-access regions such as regions in the heart are depicted inFIGS. 11 to 25.

One variation of a tissue access and imaging apparatus is shown in the detail perspective views ofFIGS. 1A to 1C. As shown inFIG. 1A, tissue imaging and manipulation assembly10may be delivered intravascularly through the patient's body in a low-profile configuration via a delivery catheter or sheath14. In the case of treating tissue, such as the mitral valve located at the outflow tract of the left atrium of the heart, 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 assembly10is ready to be utilized for imaging tissue, imaging hood12may be advanced relative to catheter14and deployed from a distal opening of catheter14, as shown by the arrow. Upon deployment, imaging hood12may be unconstrained to expand or open into a deployed imaging configuration, as shown inFIG. 1B. Imaging hood12may 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 hood12may 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 hood12may 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 hood12may 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 surface13of imaging hood12will be significantly less than a volume of the hood12between inner surface13and outer surface11.

Imaging hood12may be attached at interface24to a deployment catheter16which may be translated independently of deployment catheter or sheath14. Attachment of interface24may be accomplished through any number of conventional methods. Deployment catheter16may define a fluid delivery lumen18as well as an imaging lumen20within which an optical imaging fiber or assembly may be disposed for imaging tissue. When deployed, imaging hood12may expand into any number of shapes, e.g., cylindrical, conical as shown, semi-spherical, etc., provided that an open area or field26is defined by imaging hood12. The open area26is the area within which the tissue region of interest may be imaged. Imaging hood12may also define an atraumatic contact lip or edge22for placement or abutment against the tissue region of interest. Moreover, the diameter of imaging hood12at its maximum fully deployed diameter, e.g., at contact lip or edge22, is typically greater relative to a diameter of the deployment catheter16(although a diameter of contact lip or edge22may be made to have a smaller or equal diameter of deployment catheter16). For instance, the contact edge diameter may range anywhere from 1 to 5 times (or even greater, as practicable) a diameter of deployment catheter16.FIG. 1Cshows an end view of the imaging hood12in its deployed configuration. Also shown are the contact lip or edge22and fluid delivery lumen18and imaging lumen20.

The imaging and manipulation assembly10may additionally define a guidewire lumen therethrough, e.g., a concentric or eccentric lumen, as shown in the side and end views, respectively, ofFIGS. 1D to 1F. The deployment catheter16may define guidewire lumen19for facilitating the passage of the system over or along a guidewire17, which may be advanced intravascularly within a body lumen. The deployment catheter16may then be advanced over the guidewire17, as generally known in the art.

In operation, after imaging hood12has been deployed, as inFIG. 1B, and desirably positioned against the tissue region to be imaged along contact edge22, the displacing fluid may be pumped at positive pressure through fluid delivery lumen18until the fluid fills open area26completely and displaces any fluid28from within open area26. The displacing fluid flow may be laminarized to improve its clearing effect and to help prevent blood from re-entering the imaging hood12. Alternatively, fluid flow may be started before the deployment takes place. The displacing fluid, also described herein as imaging fluid, may comprise any biocompatible fluid, e.g., saline, water, plasma, etc., which is sufficiently transparent to allow for relatively undistorted visualization through the fluid. Alternatively or additionally, any number of therapeutic drugs may be suspended within the fluid or may comprise the fluid itself which is pumped into open area26and which is subsequently passed into and through the heart and the patient body.

As seen in the example ofFIGS. 2A and 2B, deployment catheter16may be manipulated to position deployed imaging hood12against 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 blood30flows around imaging hood12and within open area26defined within imaging hood12, as seen inFIG. 2A, the underlying annulus A is obstructed by the opaque blood30and is difficult to view through the imaging lumen20. The translucent fluid28, such as saline, may then be pumped through fluid delivery lumen18, intermittently or continuously, until the blood30is at least partially, and preferably completely, displaced from within open area26by fluid28, as shown inFIG. 2B.

Although contact edge22need not directly contact the underlying tissue, it is at least preferably brought into close proximity to the tissue such that the flow of clear fluid28from open area26may be maintained to inhibit significant backflow of blood30back into open area26. Contact edge22may also be made of a soft elastomeric material such as certain soft grades of silicone or polyurethane, as typically known, to help contact edge22conform to an uneven or rough underlying anatomical tissue surface. Once the blood30has been displaced from imaging hood12, an image may then be viewed of the underlying tissue through the clear fluid30. This image may then be recorded or available for real-time viewing for performing a therapeutic procedure. The positive flow of fluid28may be maintained continuously to provide for clear viewing of the underlying tissue. Alternatively, the fluid28may 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 flow28may cease and blood30may be allowed to seep or flow back into imaging hood12. This process may be repeated a number of times at the same tissue region or at multiple tissue regions.

In desirably positioning the assembly at various regions within the patient body, a number of articulation and manipulation controls may be utilized. For example, as shown in the articulatable imaging assembly40inFIG. 3A, one or more push-pull wires42may be routed through deployment catheter16for steering the distal end portion of the device in various directions46to desirably position the imaging hood12adjacent to a region of tissue to be visualized. Depending upon the positioning and the number of push-pull wires42utilized, deployment catheter16and imaging hood12may be articulated into any number of configurations44. The push-pull wire or wires42may be articulated via their proximal ends from outside the patient body manually utilizing one or more controls. Alternatively, deployment catheter16may be articulated by computer control, as further described below.

Additionally or alternatively, an articulatable delivery catheter48, which may be articulated via one or more push-pull wires and having an imaging lumen and one or more working lumens, may be delivered through the deployment catheter16and into imaging hood12. With a distal portion of articulatable delivery catheter48within imaging hood12, the clear displacing fluid may be pumped through delivery catheter48or deployment catheter16to clear the field within imaging hood12. As shown inFIG. 3B, the articulatable delivery catheter48may be articulated within the imaging hood to obtain a better image of tissue adjacent to the imaging hood12. Moreover, articulatable delivery catheter48may be articulated to direct an instrument or tool passed through the catheter48, as described in detail below, to specific areas of tissue imaged through imaging hood12without having to reposition deployment catheter16and re-clear the imaging field within hood12.

Alternatively, rather than passing an articulatable delivery catheter48through the deployment catheter16, a distal portion of the deployment catheter16itself may comprise a distal end49which is articulatable within imaging hood12, as shown inFIG. 3C. Directed imaging, instrument delivery, etc., may be accomplished directly through one or more lumens within deployment catheter16to specific regions of the underlying tissue imaged within imaging hood12.

Visualization within the imaging hood12may be accomplished through an imaging lumen20defined through deployment catheter16, as described above. In such a configuration, visualization is available in a straight-line manner, i.e., images are generated from the field distally along a longitudinal axis defined by the deployment catheter16. Alternatively or additionally, an articulatable imaging assembly having a pivotable support member50may be connected to, mounted to, or otherwise passed through deployment catheter16to provide for visualization off-axis relative to the longitudinal axis defined by deployment catheter16, as shown inFIG. 4A. Support member50may have an imaging element52, e.g., a CCD or CMOS imager or optical fiber, attached at its distal end with its proximal end connected to deployment catheter16via a pivoting connection54.

If one or more optical fibers are utilized for imaging, the optical fibers58may be passed through deployment catheter16, as shown in the cross-section ofFIG. 4B, and routed through the support member50. The use of optical fibers58may provide for increased diameter sizes of the one or several lumens56through deployment catheter16for the passage of diagnostic and/or therapeutic tools therethrough. Alternatively, electronic chips, such as a charge coupled device (CCD) or a CMOS imager, which are typically known, may be utilized in place of the optical fibers58, in which case the electronic imager may be positioned in the distal portion of the deployment catheter16with electric wires being routed proximally through the deployment catheter16. Alternatively, the electronic imagers may be wirelessly coupled to a receiver for the wireless transmission of images. Additional optical fibers or light emitting diodes (LEDs) can be used to provide lighting for the image or operative theater, as described below in further detail. Support member50may be pivoted via connection54such that the member50can be positioned in a low-profile configuration within channel or groove60defined in a distal portion of catheter16, as shown in the cross-section ofFIG. 4C. During intravascular delivery of deployment catheter16through the patient body, support member50can be positioned within channel or groove60with imaging hood12also in its low-profile configuration. During visualization, imaging hood12may be expanded into its deployed configuration and support member50may be deployed into its off-axis configuration for imaging the tissue adjacent to hood12, as inFIG. 4A. Other configurations for support member50for off-axis visualization may be utilized, as desired.

FIG. 4Dshows a partial cross-sectional view of an example where one or more optical fiber bundles62may be positioned within the catheter and within imaging hood12to provide direct in-line imaging of the open area within hood12.FIG. 4Eshows another example where an imaging element64(e.g., CCD or CMOS electronic imager) may be placed along an interior surface of imaging hood12to provide imaging of the open area such that the imaging element64is off-axis relative to a longitudinal axis of the hood12. The off-axis position of element64may provide for direct visualization and uninhibited access by instruments from the catheter to the underlying tissue during treatment.

FIG. 5shows an illustrative cross-sectional view of a heart H having tissue regions of interest being viewed via an imaging assembly10. In this example, delivery catheter assembly70may be introduced percutaneously into the patient's vasculature and advanced through the superior vena cava SVC and into the right atrium RA. The delivery catheter or sheath72may be articulated through the atrial septum AS and into the left atrium LA for viewing or treating the tissue, e.g., the annulus A, surrounding the mitral valve MV. As shown, deployment catheter16and imaging hood12may be advanced out of delivery catheter72and brought into contact or in proximity to the tissue region of interest. In other examples, delivery catheter assembly70may be advanced through the inferior vena cava IVC, if so desired. Moreover, other regions of the heart H, e.g., the right ventricle RV or left ventricle LV, may also be accessed and imaged or treated by imaging assembly10.

In accessing regions of the heart H or other parts of the body, the delivery catheter or sheath14may comprise a conventional intra-vascular catheter or an endoluminal delivery device. Alternatively, robotically-controlled delivery catheters may also be optionally utilized with the imaging assembly described herein, in which case a computer-controller74may be used to control the articulation and positioning of the delivery catheter14. An example of a robotically-controlled delivery catheter which may be utilized is described in further detail in US Pat. Pub. 2002/0087169 A1 to Brock et al. entitled “Flexible Instrument”, which is incorporated herein by reference in its entirety. Other robotically-controlled delivery catheters manufactured by Hansen Medical, Inc. (Mountain View, Calif.) may also be utilized with the delivery catheter14.

To facilitate stabilization of the deployment catheter16during a procedure, one or more inflatable balloons or anchors76may be positioned along the length of catheter16, as shown inFIG. 6A. For example, when utilizing a transseptal approach across the atrial septum AS into the left atrium LA, the inflatable balloons76may be inflated from a low-profile into their expanded configuration to temporarily anchor or stabilize the catheter16position relative to the heart H.FIG. 6Bshows a first balloon78inflated whileFIG. 6Calso shows a second balloon80inflated proximal to the first balloon78. In such a configuration, the septal wall AS may be wedged or sandwiched between the balloons78,80to temporarily stabilize the catheter16and imaging hood12. A single balloon78or both balloons78,80may be used. Other alternatives may utilize expandable mesh members, malecots, or any other temporary expandable structure. After a procedure has been accomplished, the balloon assembly76may be deflated or re-configured into a low-profile for removal of the deployment catheter16.

To further stabilize a position of the imaging hood12relative to a tissue surface to be imaged, various anchoring mechanisms may be optionally employed for temporarily holding the imaging hood12against the tissue. Such anchoring mechanisms may be particularly useful for imaging tissue which is subject to movement, e.g., when imaging tissue within the chambers of a beating heart. A tool delivery catheter82having at least one instrument lumen and an optional visualization lumen may be delivered through deployment catheter16and into an expanded imaging hood12. As the imaging hood12is brought into contact against a tissue surface T to be examined, anchoring mechanisms such as a helical tissue piercing device84may be passed through the tool delivery catheter82, as shown inFIG. 7A, and into imaging hood12.

The helical tissue engaging device84may be torqued from its proximal end outside the patient body to temporarily anchor itself into the underlying tissue surface T. Once embedded within the tissue T, the helical tissue engaging device84may be pulled proximally relative to deployment catheter16while the deployment catheter16and imaging hood12are pushed distally, as indicated by the arrows inFIG. 7B, to gently force the contact edge or lip22of imaging hood against the tissue T. The positioning of the tissue engaging device84may be locked temporarily relative to the deployment catheter16to ensure secure positioning of the imaging hood12during a diagnostic or therapeutic procedure within the imaging hood12. After a procedure, tissue engaging device84may be disengaged from the tissue by torquing its proximal end in the opposite direction to remove the anchor form the tissue T and the deployment catheter16may be repositioned to another region of tissue where the anchoring process may be repeated or removed from the patient body. The tissue engaging device84may also be constructed from other known tissue engaging devices such as vacuum-assisted engagement or grasper-assisted engagement tools, among others.

Although a helical anchor84is shown, this is intended to be illustrative and other types of temporary anchors may be utilized, e.g., hooked or barbed anchors, graspers, etc. Moreover, the tool delivery catheter82may be omitted entirely and the anchoring device may be delivered directly through a lumen defined through the deployment catheter16.

In another variation where the tool delivery catheter82may be omitted entirely to temporarily anchor imaging hood12,FIG. 7Cshows an imaging hood12having one or more tubular support members86, e.g., four support members86as shown, integrated with the imaging hood12. The tubular support members86may define lumens therethrough each having helical tissue engaging devices88positioned within. When an expanded imaging hood12is to be temporarily anchored to the tissue, the helical tissue engaging devices88may be urged distally to extend from imaging hood12and each may be torqued from its proximal end to engage the underlying tissue T. Each of the helical tissue engaging devices88may be advanced through the length of deployment catheter16or they may be positioned within tubular support members86during the delivery and deployment of imaging hood12. Once the procedure within imaging hood12is finished, each of the tissue engaging devices88may be disengaged from the tissue and the imaging hood12may be repositioned to another region of tissue or removed from the patient body.

An illustrative example is shown inFIG. 8Aof a tissue imaging assembly connected to a fluid delivery system90and to an optional processor98and image recorder and/or viewer100. The fluid delivery system90may generally comprise a pump92and an optional valve94for controlling the flow rate of the fluid into the system. A fluid reservoir96, fluidly connected to pump92, may hold the fluid to be pumped through imaging hood12. An optional central processing unit or processor98may be in electrical communication with fluid delivery system90for controlling flow parameters such as the flow rate and/or velocity of the pumped fluid. The processor98may also be in electrical communication with an image recorder and/or viewer100for directly viewing the images of tissue received from within imaging hood12. Imager recorder and/or viewer100may also be used not only to record the image but also the location of the viewed tissue region, if so desired.

Optionally, processor98may also be utilized to coordinate the fluid flow and the image capture. For instance, processor98may be programmed to provide for fluid flow from reservoir96until the tissue area has been displaced of blood to obtain a clear image. Once the image has been determined to be sufficiently clear, either visually by a practitioner or by computer, an image of the tissue may be captured automatically by recorder100and pump92may be automatically stopped or slowed by processor98to cease the fluid flow into the patient. Other variations for fluid delivery and image capture are, of course, possible and the aforementioned configuration is intended only to be illustrative and not limiting.

FIG. 8Bshows a further illustration of a hand-held variation of the fluid delivery and tissue manipulation system110. In this variation, system110may have a housing or handle assembly112which can be held or manipulated by the physician from outside the patient body. The fluid reservoir114, shown in this variation as a syringe, can be fluidly coupled to the handle assembly112and actuated via a pumping mechanism116, e.g., lead screw. Fluid reservoir114may be a simple reservoir separated from the handle assembly112and fluidly coupled to handle assembly112via one or more tubes. The fluid flow rate and other mechanisms may be metered by the electronic controller118.

Deployment of imaging hood12may be actuated by a hood deployment switch120located on the handle assembly112while dispensation of the fluid from reservoir114may be actuated by a fluid deployment switch122, which can be electrically coupled to the controller118. Controller118may also be electrically coupled to a wired or wireless antenna124optionally integrated with the handle assembly112, as shown in the figure. The wireless antenna124can be used to wirelessly transmit images captured from the imaging hood12to a receiver, e.g., via Bluetooth® wireless technology (Bluetooth SIG, Inc., Bellevue, Wash.), RF, etc., for viewing on a monitor128or for recording for later viewing.

Articulation control of the deployment catheter16, or a delivery catheter or sheath14through which the deployment catheter16may be delivered, may be accomplished by computer control, as described above, in which case an additional controller may be utilized with handle assembly112. In the case of manual articulation, handle assembly112may incorporate one or more articulation controls126for manual manipulation of the position of deployment catheter16. Handle assembly112may also define one or more instrument ports130through which a number of intravascular tools may be passed for tissue manipulation and treatment within imaging hood12, as described further below. Furthermore, in certain procedures, fluid or debris may be sucked into imaging hood12for evacuation from the patient body by optionally fluidly coupling a suction pump132to handle assembly112or directly to deployment catheter16.

As described above, fluid may be pumped continuously into imaging hood12to provide for clear viewing of the underlying tissue. Alternatively, fluid 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 may cease and the blood may be allowed to seep or flow back into imaging hood12.FIGS. 9A to 9Cillustrate an example of capturing several images of the tissue at multiple regions. Deployment catheter16may be desirably positioned and imaging hood12deployed and brought into position against a region of tissue to be imaged, in this example the tissue surrounding a mitral valve MV within the left atrium of a patient's heart. The imaging hood12may be optionally anchored to the tissue, as described above, and then cleared by pumping the imaging fluid into the hood12. Once sufficiently clear, the tissue may be visualized and the image captured by control electronics118. The first captured image140may be stored and/or transmitted wirelessly124to a monitor128for viewing by the physician, as shown inFIG. 9A.

The deployment catheter16may be then repositioned to an adjacent portion of mitral valve MV, as shown inFIG. 9B, where the process may be repeated to capture a second image142for viewing and/or recording. The deployment catheter16may again be repositioned to another region of tissue, as shown inFIG. 9C, where a third image144may be captured for viewing and/or recording. This procedure may be repeated as many times as necessary for capturing a comprehensive image of the tissue surrounding mitral valve MV, or any other tissue region. When the deployment catheter16and imaging hood12is repositioned from tissue region to tissue region, the pump may be stopped during positioning and blood or surrounding fluid may be allowed to enter within imaging hood12until the tissue is to be imaged, where the imaging hood12may be cleared, as above.

As mentioned above, when the imaging hood12is cleared by pumping the imaging fluid within for clearing the blood or other bodily fluid, the fluid may be pumped continuously to maintain the imaging fluid within the hood12at a positive pressure or it may be pumped under computer control for slowing or stopping the fluid flow into the hood12upon detection of various parameters or until a clear image of the underlying tissue is obtained. The control electronics118may also be programmed to coordinate the fluid flow into the imaging hood12with various physical parameters to maintain a clear image within imaging hood12.

One example is shown inFIG. 10Awhich shows a chart150illustrating how fluid pressure within the imaging hood12may be coordinated with the surrounding blood pressure. Chart150shows the cyclical blood pressure156alternating between diastolic pressure152and systolic pressure154over time T due to the beating motion of the patient heart. The fluid pressure of the imaging fluid, indicated by plot160, within imaging hood12may be automatically timed to correspond to the blood pressure changes160such that an increased pressure is maintained within imaging hood12which is consistently above the blood pressure156by a slight increase ΔP, as illustrated by the pressure difference at the peak systolic pressure158. This pressure difference, ΔP, may be maintained within imaging hood12over the pressure variance of the surrounding blood pressure to maintain a positive imaging fluid pressure within imaging hood12to maintain a clear view of the underlying tissue. One benefit of maintaining a constant ΔP is a constant flow and maintenance of a clear field.

FIG. 10Bshows a chart162illustrating another variation for maintaining a clear view of the underlying tissue where one or more sensors within the imaging hood12, as described in further detail below, may be configured to sense pressure changes within the imaging hood12and to correspondingly increase the imaging fluid pressure within imaging hood12. This may result in a time delay, ΔT, as illustrated by the shifted fluid pressure160relative to the cycling blood pressure156, although the time delays ΔT may be negligible in maintaining the clear image of the underlying tissue. Predictive software algorithms can also be used to substantially eliminate this time delay by predicting when the next pressure wave peak will arrive and by increasing the pressure ahead of the pressure wave's arrival by an amount of time equal to the aforementioned time delay to essentially cancel the time delay out.

The variations in fluid pressure within imaging hood12may be accomplished in part due to the nature of imaging hood12. An inflatable balloon, which is conventionally utilized for imaging tissue, may be affected by the surrounding blood pressure changes. On the other hand, an imaging hood12retains a constant volume therewithin and is structurally unaffected by the surrounding blood pressure changes, thus allowing for pressure increases therewithin. The material that hood12is made from may also contribute to the manner in which the pressure is modulated within this hood12. A stiffer hood material, such as high durometer polyurethane or Nylon, may facilitate the maintaining of an open hood when deployed. On the other hand, a relatively lower durometer or softer material, such as a low durometer PVC or polyurethane, may collapse from the surrounding fluid pressure and may not adequately maintain a deployed or expanded hood.

In further controlling the flow of the purging fluid within the hood12, various measures may be taken in configuring the assembly to allow for the infusion and controlled retention of the clearing fluid into the hood. By controlling the infusion and retention of the clearing fluid, the introduction of the clearing fluid into the patient body may be limited and the clarity of the imaging of the underlying tissue through the fluid within the hood12may be maintained for relatively longer periods of time by inhibiting, delaying, or preventing the infusion of surrounding blood into the viewing field.

In utilizing the hood12and various instruments through the hood for tissue treatment, hood12may be articulated in a variety of configurations to facilitate the access to regions within the heart. For instance, access to the left atrium of a patient's heart for performing treatments such as tissue ablation for atrial fibrillation may require hood12to be retroflexed in various configurations to enable sufficient access. Thus, the ability to control the steering or articulation of hood12within the patient's heart may facilitate tissue visualization and treatment.

FIG. 11Ashows a side view variation of the steerable tissue visualization catheter with multiple plane steering guided by keyhole lumens. As shown inFIG. 11A, one variation of the visualization catheter may comprise a tubular member such as an extrusion206having grooves defined off the catheter leaving a pull mechanism exposed at desired intervals. Steerable segment202can be laser cut from tubes, double durometer extrusion, and rink links, for example. Pull mechanism204is exposed at desired intervals. Distal to extrusion206is hood210coupled to and extending distally from the steerable segment202. An imaging element212is also found in hood210where the imaging element can be a CMOS or CCD camera with light source, as described above. The imaging element212can also be a high resolution optical fiber scope (with light source) positioned in one of the channels of the multi-lumen extrusion206. The steerable segment202of the catheter reveals pull wires204at desired intervals within extrusion206. The pull wire204can be made from stainless steel, Nitinol, elgiloy, tungsten, etc.

When pull wire204is tensioned, the exposed portions of the catheter may function as pivoting sections biasing the catheter to bend in predetermined directions. Keyhole lumens may be utilized through sections of the steerable segment202, as illustrated in the cross-sectional views ofFIGS. 11C,11D, and11E which are exemplary cross-sectional views that portions of segment202may include. As shown, each respective lumen may define a first main region of the lumen214and a second keyed region216extending from first main region214at predefined orientations. The relative positioning of keyed region216relative to main region214may be varied to alter the natural direction which segment202may articulate or bend. Further details of such a visualization catheter and methods of use are shown and described in U.S. Pat. Pub. 2006/0184048 A1, which is incorporated herein by reference in its entirety.

FIGS. 12A and 12Billustrate a comparison of a device having a large bending radius222relative to a device having a smaller bending radius224in respective steerable segments202.FIGS. 12A and 12Balso both have steering guides218and steering actuator220, the adjustment of which will provide the necessary bend in the catheter shaft.FIG. 12Cdepicts the cross-sectional view of a steering actuator220, which can be, e.g. pullwires or a fiberscope. Steering guide218directs the bend in the shaft as shown inFIGS. 12A and 12B, and is shown in the cross-sectional end and side views ofFIGS. 12C and 12Din relationship to the actuator220.

FIG. 13Adepicts a device having a pullwire204running within a steerable segment202having a segmented shaft with articulatable segments226. Steering guide218and actuator220are depicted in cross section inFIG. 13Band in side view inFIG. 13C. The steering guide and actuator operate together within the steerable segment202. The articulatable segments206can be bent and conformed along the steerable segment as the guide and actuator slide in relation to each other.

With regard to the articulatable segments226, various types of links may be utilized to affect a corresponding articulation. The links may be ring links, “bump” links e.g. contoured links having a distal curved surface that is convex in shape, and a proximal curved surface that is concave in shape, such that when serially aligned with a similar link, the curved convex distal surface of one link mates correspondingly with the curved concave proximal surface of the adjacent link and allows the relative pivoting or rocking between the adjacent links along a defined plane. Links may also be pinned links each having a pin running through it, laser cut tubes or double durometer extrusions.

Each of the links226may define one or more channels therethrough such that when a plurality of links226are aligned and mated to one another, each individual channel forms a continuous lumen through the segment. A lining, such as an elastic heat shrink polymer, may be coated upon the link segments to ensure a smooth surface along the links. Moreover, the links can be made from materials such as stainless steel, PEEK, hard plastics, etc., and manufactured through machining, molding, metal injection molding, etc.

Further examples of links and details of additional variations in steering configurations and mechanisms which may be utilized herein are shown and described in further detail in U.S. patent Application Ser. No. 12/108,812 filed Apr. 24, 2008, which is incorporated herein by reference in its entirety.

FIG. 14Aillustrates a perspective view of a distal section of the device having a hood210at a distal end of steerable segment202. Steering actuator220includes in this embodiment pullwires and steering guide tube218serves to manipulate the bend achieved by the pullwires220. The links226are shown here as ring links.FIG. 14Bdepicts a similar variation, except that the steering guide is a tube228and as tube228retains the steering actuator220which in this embodiment is a pullwire. The steerable segment inFIG. 14Balso has articulatable segments226.

FIGS. 15A and 15Bdepict a variation having both keyhole extrusion mechanisms and steering guides combined in the same device. The steerable segment232may be guided by both keyhole extrusions and steering guides, as described above. The steerable segment232can be constructed with various architectures, such as pullwires, pull tubes, imaging fiberscopes, illumination fiberscopes, or tools such as needles, graspers, electrodes, or guidewires for example. InFIG. 15A, steerable segment232is shown in a cross-sectional end view inFIG. 15Cwhich depicts both the key-hole extrusions and the steering actuator220and guide tube228. Likewise,FIG. 15Ddepicts the steerable segment232bending230where the steering guide and actuator tightly bend using steering guide218and steering actuator220.

FIGS. 16A to 16Gillustrate several types of motion possible with the steerable hood device. In particular,FIG. 16Adepicts articulation steering within a plane of the proximal segment234(also identified as segment “Y”) and “twist” steering or rotational steering of the distal segment236(also identified as segment “X”) about a longitudinal axis of the catheter, proximal to the hood210. Twist steering is accomplished using keyhole extrusions depicted above. As a result of the combined motion, steerable segment202may bends and twists about its longitudinal axis, as shown.

FIG. 16Bdepicts the device configured with twist steering along distal segment236combined with retroflex articulation242along proximal segment240. Retroflex steering can be enabled by steering mechanisms and methods disclosed herein. Retroflex steering allows hood210to be configured out-of-plane relative to a proximal portion of the device.

FIGS. 16C to 16Gillustrates the hood210being configured by a series of complex steering manipulations to allow for engagement of the hood210perpendicularly relative to the direction of approach taken to reach the tissue. Accordingly, this series of manipulations could be used to bend the hood210directly perpendicular to the direction used to arrive at the target location. In these illustrations, proximal segment Y is shown being articulated to curve within a plane coincident with the catheter inFIGS. 16C to 16E. As proximal segment Y is curved (or once segment Y has been fully articulated), distal segment X may be articulated to twist about itself such that distal segment X is moved out-of-plane with respect to segment Y and the remainder of the catheter, as shown inFIGS. 16F and 16G. This series of manipulations resulting in the perpendicular approach of the hood relative to the rest of the device can be applied to navigate the hood in body lumens, especially when space is limited, for locating and establishing direct visualization of tissue surfaces/features such as the fossa ovalis, the coronary sinus, and pulmonary veins.

FIGS. 17A to 17Dillustrate partial cross-sectional side views of a catheter introduced within the patient's heart250and articulated to conform into complex configurations. As shown, an introducer sheath244may be advanced intravascularly, in this example through the superior vena cava, into the right atrial chamber to access the atrial septum. Introducer sheath244is placed in the right atrium, as inFIG. 17B, and used to deploy the steerable visualization catheter246through to the right atrium. At this location, as inFIG. 17C, the catheter246may be articulated to form curve248in a manner described above such that the hood is moved into an out-of-plane configuration that positions the hood perpendicular to the target tissue surface.FIG. 17Dcompletes the access to the target tissue252when the distal hood contacts the tissue surface in a perpendicular angle, facilitated by the complex curve steering.

FIGS. 18A to 18Cdepict perspective, side, and end views of a variation of the tissue visualization catheter having a steerable retro-flexing sheath254that controls the proximal segment, as shown inFIG. 18A.FIG. 18Bdepicts a partial cross-sectional side view a lumen defined in the wall of the sheath260to house a pullwire220or other steering mechanism. The pullwire220is terminated at distal end258of the introducer sheath254while the introducer sheath distal end256may extend beyond the termination region of the pullwire220.FIG. 18Cdepicts further details of the introducer sheath262in a cross-sectional end view illustrating pullwire220housed in lumen260within the wall of the sheath. Proximal handle264controls the pullwire or other steering mechanism.

FIGS. 19A and 19Bdepict a steerable introducer sheath directing a visualization hood210into the heart250to access the left264and right266pulmonary veins. Curve268is generated by the manipulations of the introducer sheath controlling the directionality of the hood210inFIG. 19B.

FIGS. 20A to 20Cshow perspective views of an apparatus having a push steering mechanism.FIG. 20Ashows steerable segment202supported by at least one rigid lateral support arm272attached to a push steering collar274on the proximal end and to a hinge270at the base of the visualization hood210.FIG. 20Bdepicts the curvature possible in steerable segment202when segment202is pushed from a proximal end to pivot hood210about hinge270. InFIG. 20B, the push steering mechanism is abutted at its proximal end with a flexible sheath276to facilitate intravascular advancement. Push steering collar274and rigid lateral support arms272push at the base of the hood210through the hinge connection that manipulates the hood210.FIG. 20Cdemonstrates an ability of the push steering mechanism to torque the catheter along a longitudinal axis to steer the hood to multiple planes. Flexible sheath276and support arms272direct and rotate distal steering segment202.

FIGS. 21A to 21Cdepict another variation of an expandable visualization hood278in which an imaging element such as CMOS/CCD can be mounted. A guidewire282can be used to access the hood to the region of interest. As shown inFIG. 21A, a steerable double bend segment202can have articulating links such as the concave/convex links described previously. More proximal still, the steerable sheath284is constructed of steerable links, in the case as depicted here, pin links in which pins connect separate articulating links to one another in a sequence.FIG. 21Billustrates detail side views of the pre-deployed visualization hood286, configured here as an expandable membrane, having imaging element280positioned within. The expandable visualization membrane278may be fully deployed once it is deployed from the catheter sheath.FIG. 21Cshows an expandable visualization hood278and imaging element280articulating in the heart in order to accomplish visualization of a region of tissue in a heart chamber.

FIG. 22Adepicts another variation of an expandable visualization membrane286through which is defined a working channel288and imaging element280positioned therealong within membrane286. Guidewire282extends through the working channel288in order to position the apparatus accurately at the target region. As previously described, steerable segment202may be formed from, e.g., bump links, and the steerable sheath proximal to segment202comprising, e.g., pin links.FIG. 22Bdepicts an expandable visualization membrane286having a working channel, where the steerable segment202is composed of ring links to provide high force transmission and steerability to the visualization hood as it is guided and positioned to a site.

FIG. 23depicts a side view of another variation of the apparatus having an expandable visualization membrane286and a distal expandable anchoring member290. The visualization membrane286contains an energy transmitter such as laser optics288for ablation therapy under direct visualization. As before, the steerable segment202depicts links that control the movement of that section.FIG. 24depicts the apparatus having an infrared camera and light source292at the distal end and a steerable segment202as described above.

FIG. 25Adepicts an assembly view of a system having multiple tools introduced through handle300. Tools depicted here include a syringe for purging the hood102, a fiberscope104, and a needle with a sheath294. Also depicted are a steering lever298connected to pullwire296. The steerable segment202of the apparatus may include, e.g., bump links, a multi-lumen extrusion206, and a needle in sheath294.FIG. 25Bdepicts a closer view of the control handle300having steering lever298at which pullwire296terminates. Valves for passing tools such as a fiberscope108, a valve for passing tools such as a needle110, and housing for the proximal end imaging elements such as a camera connector of a fiber scope112are also shown.FIG. 25Cshows a larger view of steering lever298in its interaction with steerable segment202to manipulate hood210. Lever298in the rear position provides tension to the pull wires threaded along the steerable segment202. Various tools are also depicted.FIG. 25Ddepicts handle300having steering lever298in a rear position providing tension to pull wires296as the steering lever pivots about a pin hinge in order to provide tension on the pullwires.

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 treatments and areas of the body. 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.