Patent ID: 12193638

DETAILED DESCRIPTION OF THE INVENTION

Various exemplary embodiments of the invention are described below. Reference is made to these examples in a non-limiting sense. They are provided to illustrate more broadly applicable aspects of the present invention. Various changes may be made to the invention described and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process act(s) or step(s) to the objective(s), spirit or scope of the present invention. All such modifications are intended to be within the scope of the claims made herein.

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 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.1-10. The specific details of the invention that permit specific access to difficult-to-access regions such as regions in the heart are depicted inFIGS.11to32. Specific embodiments depicting devices and methods for specific heart-based tissue manipulations such as forming lesions around the pulmonary ostia are shown inFIGS.28to32.

One variation of a tissue access and imaging apparatus is shown in the detail perspective views ofFIGS.1A to1C. 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, DE), 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 to1F. 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 and2B, 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, CA) 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 system HO. 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, WA), 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 to9Cillustrate 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 variation of the tissue visualization catheter with an example of steering features. As shown inFIG.11A, one variation of the visualization catheter may comprise a tubular member such as an extrusion206(which may define a multi-lumen extrusion) and a steerable segment202distal to extrusion206with 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 visualization catheter may be further translated along a single lumen catheter sheath208that allows the visualization catheter to retract into or be deployed from the catheter sheath208. The steerable segment202of the catheter may be also coated with a thin liner204to ensure the surface of the steerable segment remains smooth and atraumatic to surrounding tissues.

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.

FIG.11BandFIG.11Cillustrates an example of the visualization catheter being steered by a pull wire mechanism. A pull wire216passing through extrusion206and steerable segment202may be terminated at distal section214of steerable segment202. The proximal end of pull wire216may be routed into a handle at the proximal end of extrusion206. As shown inFIG.11C, the steerable segment202is steered into a curved configuration when the pull wire216is tensioned from its proximal end. The interaction between the tensioning and the bending of steerable segment202of the catheter enables the hood210to articulate across a range of angles. The pull wire216can be made from stainless steel, nitinol, elgiloy, tungsten, etc.

Shown inFIG.11D, by combining torquing of the visualization catheter about the longitudinal axis of the extrusion, hood210may be rotated in various directions218and220to access more areas with the steering segment202.

FIG.12Ashows a similar embodiment with a double pull wire mechanism to steer the tissue visualization catheter into a double-bend configuration. As shown, a first pull wire213may be terminated at a first location214along the steerable segment202proximal to hood210while a second pull wire221may be terminated at a second location222along steerable segment202proximal to the first location214. The first and second locations214,222may both be located along segment202so long as they are staggered with respect to one another. Moreover, they may terminate along opposite angles of segment202to provide opposing bending moments, as described further below. When second pull wire221is tensioned, as shownFIG.12B, hood210and segment202may be curved in a first direction with respect to a longitudinal axis of the sheath. First pull wire213may also be tensioned (before, after, or simultaneously with second pull wire221) such that steerable segment202is articulated into a double-bend configuration, as shown inFIG.12C, where a first curve224(defined as Curve A) is curved in an opposite direction from second curve226(defined as Curve B). Although hood210is illustrated in a perpendicular angle relative to the sheath, the degree of tensioning of pull wires213,221may be varied to result in a variable angle which hood210may be configured.

FIG.12Dillustrates the articulated deployment catheter ofFIG.12Cpositioned within a body lumen where hood210is accessing a target tissue along a relatively narrow region. To access the target tissue, first curve224and second curve226may be actuated to position hood210in a perpendicular configuration relative to the sheath. The proximal portion of the deployment catheter and the sheath may be maintained a distance228from a surface of the tissue to be visualized and/or treated while the dual-curved configuration also allows segment202to maintain a gentle bend radius throughout even if a relatively tight perpendicular bend is attained.

FIG.13Ashows another variation of the steerable tissue visualization catheter with 2 pairs of pull wires terminated distally and proximally along steerable segment202of the catheter. First pull wire213and second pull wire221may be positioned and terminated as above, and third pull wire215may extend distally along segment202to terminate at third location230proximal to hood210and adjacent to first location214along an opposing side of segment202relative to first location214. Fourth pull wire223may extend along segment202and terminate at fourth location232which is adjacent to second location222along an opposing side of segment202.

First pull wire213and second pull wire221may be tensioned to articulate segment202and hood210in a configuration where first curve224and second curve226are aligned in opposing directions, as above and as shown inFIG.13B. Third and fourth pull wires215and223may remain slack during this articulation. However, rather than torquing segment202and hood210around to reposition hood210along an opposite side, first and second pull wires213and221may be released and third and fourth pull wires215and223may be tensioned to articulate hood210in an opposing direction, as illustrated inFIG.13C. Alternatively, in actuating pull wires located along a common side of segment202, e.g., third pull wire215and second pull wire221as shown inFIG.13D, segment202may be articulated to fully retroflex hood210proximally relative to a longitudinal axis of the deployment catheter. Although four separate pull wires are illustrated, fewer than or greater than four pull wires may be utilized and positioned along segment202depending upon the desired degree of articulation.

The pullwire mechanism can also interact to produce push steering motions as shown inFIGS.13E and13Fwhere hood210may be placed against the tissue surface to be visualized and/or treated and the pull wires may be tensioned in a manner to push or urge hood210into direct intimate contact against the tissue surface. This can be achieved, for instance, by tensioning the appropriate pull wires to articulate hood210in a perpendicular angle, as described above and as shown in the side view ofFIG.13E. With hood210initially positioned along the tissue surface to be visualized and/or treated, pull wires213,221may be tensioned and locked in place, as shown inFIG.13G. The pushing motion of hood210can be defined as the reduction of first curve224while the steerable segment202remains rigid in a double bend configuration.

FIGS.14A to14Eillustrate another variation of a pull wire mechanism where multiple pull wires, four in this instance, are attached at a distal location238of steerable segment250proximal to hood210. The pull wires may be positioned around a segment250uniformly spaced apart from one another. Thus, first pull wire240, second pull wire242, third pull wire244, and fourth pull wire246may be aligned parallel to another and terminate at a common location238such that tensioning each of the pull wires allows for segment250and hood210to be articulated accordingly. With each pull wire relaxed, as shown inFIG.14A, hood210may extend distally while tensioning second and or fourth pull wires242and246may articulate hood210to curve appropriately, as shown inFIG.14B. Likewise, tensioning first and/or third pull wires240and244may articulate hood210in a second direction, as shown inFIG.14Cand tensioning of second and/or third pull wires242and244or tensioning of first and/or fourth pull wires240and246may articulate hood210accordingly, as shown inFIGS.14D and14E. Various combinations of tensioning various pull wires may accordingly effect any number of configurations for hood210.

Turning now to the articulatable segments, various types of links may be utilized to affect a corresponding articulation. For example,FIG.15Ashows a perspective view of a variation of the tissue visualization catheter where the steerable segment may utilize serially aligned multiple links which collectively facilitate hood articulation. This particular variation illustrates the use of contoured links252, e.g., “bump” links as shown in the perspective view ofFIG.15B, which define a distal curved surface254, e.g., convex in shaped, and a proximal curved surface256, e.g., concave in shape, such that when serially aligned with a similar link, the curved convex distal surface254of one link mates correspondingly with the curved concave proximal surface256of the adjacent link and allows the relative pivoting or rocking between the adjacent links along a defined plane, as shown in the detail side view ofFIG.15C.

Each of the links252may define one or more channels258therethrough such that when a plurality of links252are aligned and mated to one another, each individual channel258forms a continuous lumen through the segment. A lining262, 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.

FIGS.15D to15Fillustrate side views of the serially aligned link252in a straightened configuration, as shown inFIG.15D, as well as articulated in a compound curve, as shown inFIG.15E, or a single curve, as shown inFIG.15F, where each link is illustrated as pivoting or rocking with respect to an adjacent link. Additionally, once the terminal extent of the relative pivoting or angling between adjacent links is reached, the extent of the curvature is reached as well, as shown in the figures.

FIG.16Ashows another variation of links which may be utilized for facilitating the articulation of segment202. In this example, rather than utilizing contoured “bump” links, pinned links264may be utilized.FIG.16Billustrates detail side views of pinned links264, each of which may form a proximal and distal recessed surface with an intersecting interface270extending axially from both sides of an individual link264. This interface270may extend and overlap with an adjacent link such that the overlapping interfaces may be aligned and pivotably connected to one another via a pin266. Rather sliding along curved interface surfaces, pinned links264may pivot about the axis of the pins266to collectively form a segment202which is constrained to articulate in a single preset plane. Similar to contoured links, pinned links264may define one or more continuous lumens. Moreover, pinned links264may be steerable via any of the pullwire mechanisms described above.

Additionally, pin linked steerable segments264may provide better control in the movement of the links as compared to other contoured links as pin links are constrained to pivot about a secured point instead of sliding along curve intersections. In addition, with pins266securing each adjacent link264, compound curves created by the steerable segment202may be relatively more rigid which in turn may provide a more secure platform for force transmission when utilizing instruments positioned therethrough. Moreover, pinned links264may also be utilized for constructing steerable introducer sheaths.

FIG.17Ashows yet another variation of the steerable segment202comprised of ring links272. As shown in the detail perspective views ofFIG.17B, circular ring links272may be comprised of a tubular member defining an opening therethrough. A distal edge274of link272may be chamfered such that this chamfered edge274is slidingly received in the proximal opening of an adjacent link. Because adjacent links272may slide freely with respect to one another, various angles and configurations may be formed. Circular ring links272may form complex rigid bends when pull wires are simultaneously tensioned. Other configurations that are not depicted are also possible with any of the link various combined in alternate configurations. The ring link embodiment can also be utilized as part of the introducer sheath to produce steerable sheaths. Similar to contoured links and pinned links, ring links can be made from materials such as, but not limited to, stainless steel, PEEK, hard plastics, etc. Moreover, rings links can be manufactured through machining, molding, metal injection molding, etc.

In addition, simultaneously tensioning all pull wires threaded along ring links272will compress each ring tightly towards each another to form a rigid segment. The rigid segment formed by the tensioned ring links may therefore “memorize” the current path taken by the catheter or sheath276and hold the catheter or sheath along this set trajectory to provide for effective force transmission for tools deployed through the catheter.

FIG.18shows a side view of another variation of a steerable segment278made from a cut tube, e.g., a laser-cut tube, having one or more pull wires therethrough. The laser cut tube278can be made from materials as described above and cut such that structural spines are formed along the outer bend radius of the steerable segment278to provide a more stable curved platform. A combination of different positions of such structural spines may yield steerable segments having a combination of different bend directions and/or bend radius.

FIG.19shows a side and perspective view of another steerable segment202that comprises a ribbed spine, e.g., a “fish bone” configuration. A continuous spine280may provide overall cohesive structural strength to the segment with ribbed extensions282extending perpendicularly from the spine280with gaps284formed at regular intervals between the extensions282to provide for flexibility of the segment. One or more pull wires286may extend through the segment through the ribbed extensions282, as illustrated in the perspective detail view ofFIG.19B. Moreover, the ribbed extensions282can be arranged at different angles about the central longitudinal axis of the deployment catheter to yield steering along different predefined directions.

In yet another variation, the steerable segment202may comprise an extrusion having a plurality of slits or cuts288made along one or both sides of the segment202such that the slits288facilitate the bending of segment202, as shown in the perspective and side views ofFIGS.20A and20B. The resulting segment202results in the slits or cuts288formed along the inner radius of a desired direction of bend. Hence, when pull wires are tensioned through segment202, the steerable segment202may bend in the direction of the slit patterns when the pullwires are pulled.FIG.20Cillustrates a detail side view of slits288showing the removed portion of material along segment202. Aside from slits or cuts, grooves, channels, or any other mechanism for the uniform removal of material along segment202may be utilized. In another variation, pull tubes will small outer diameter then thin wall thickness can be used in place of pullwires. In this variation, the pull tubes that steers the steerable segment can double up as a narrow work channel lumen for works such as guidewires or fiberscopes.

FIGS.21A and21Bshow perspective and side views of another variation utilizing an extrusion comprised of two or more sections having different durometer values and/or material utilized as a steerable section. The example illustrates a variation having two sections, a first section290having a first durometer and a second section292having a second durometer which has a relatively higher durometer value than first section290. This variation may accordingly produce a flexible segment that when articulated utilizing any of the mechanisms described herein has a relatively stiffer second section292and a relatively more flexible first section290. The segment202may be extruded into a continuous segment or individual segments may be extruded separately and joined together at a joint275. Moreover, the segment may be extruded such that the durometer value gradually declines the farther distal along the segment. Alternatively, the second section292may be configured to have a lower durometer value than the first section290.

Aside from articulatable segments along the deployment catheter for positioning the hood relative to the tissue, other variations may articulate the hood assembly by utilizing a combination of the introducer sheath294and deployment catheter276. As previously mentioned, a portion of the sheath itself, e.g., a distal portion, may also incorporate an articulatable section298which may be either pre-bent or actively steered depending upon the desired results. Thus, compound curve articulation can be made through active steering of both sheath and deployment catheter and/or passive steering of both or either sheath and deployment catheter.

FIG.22Ashows a side view of a visualization assembly210having the actively articulated double-bend steering described above along with a sheath294having an articulatable distal segment298. In this example, distal segment298is illustrated as being pre-bent such that when the distal segment298is unconstrained, segment298relaxes into a pre-bent configuration as shown. Thus when deployed, hood210may be articulated into position relative to the tissue surface via at least three curvable or curved sections, e.g., first curve224(Curve A), second curve226(Curve B), and third curve302defined by the distal segment298of sheath294(Curve C). By varying the tension and/or articulation between each of the curves, hood210may be positioned in a variety of configurations and angles. Additionally, the deployment catheter may be translated and/or rotated, as shown by directional indication296about a longitudinal axis of the catheter relative to sheath294to further provide additional degrees-of-freedom.

Rather than utilizing the double-bend system, a single curve along the segment202may be utilized with the sheath294. As illustrated in the side view ofFIG.22B, a single curve, e.g., second curve226may be articulated when advanced distally of distal segment298of sheath294such that the second curve226is articulated in a direction opposition to the curvature of distal segment298. Alternatively, second curve226may be articulated to curve in the same direction as the curvature of third curve302such that hood210is retroflexed proximally relative to sheath294, as illustrated inFIG.22C.

By utilizing one or all curves available through the combination of the deployment catheter with the sheath, the assembly may be used to access any region within a body lumen. For instance,FIG.22Dillustrates a partial cross-sectional view of hood assembly210advanced intravascularly through the inferior vena cava IVC and into the right atrium RA of a patient's heart. Segment202may be initially directed by third curve302of sheath294towards a region of tissue to be examined and/or treated. By rotating sheath294relative to the right atrium RA, an initial trajectory of hood210as well as articulatable segment202may be effectively directed. As hood210is deployed, first224, second226, and third curves294may be configured desirably to direct hood210towards a tissue region such as the atrial septum AS, e.g., for potentially accessing the left atrium LA of the heart, as shown inFIG.22E. As further illustrated inFIG.22F, hood210and segment202may be rotated relative to sheath294to redirect or reposition hood210on another region of tissue.

FIG.23Ashows another variation of the steering system utilizing a steerable or pre-bent sheath294in combination with a pre-bent catheter304which may be straightened when constrained for intravascular delivery but free to reconfigure into a pre-bent shape with a first curve224when unconstrained. As shown inFIG.23B, catheter304may be advanced through sheath294until hood210is deployed and catheter curve224is unconstrained by sheath294. The example ofFIG.23Bshows how first curve224of deployment catheter304may be aligned with third curve302of distal segment298within the same plane and same direction to retroflex hood210relative to sheath294. Alternatively, catheter304may be torqued or initially advanced from sheath294such that first curve224is aligned in an opposite direction from third curve302, as shown inFIG.23C. Additionally, deployment catheter304may be torqued or initially advanced from sheath294such that first curve224is aligned in a non-planar configuration, e.g., perpendicularly, relative to third curve302, as shown inFIG.23D. Although specific directions and angles may be shown, these are intended to be illustrative and any various combinations of angles and configurations may be performed by the assembly.

FIG.24Ashows a side view of yet another variation utilizing a sheath294having a steerable or pre-bent segment298in combination with a deployment catheter276having an actively steered segment which may articulate hood210at an angle Φ relative to a longitudinal axis275of the deployment catheter276. In this configuration, segment298of sheath294may provide the initial trajectory, as indicated by angle Ψ relative to a longitudinal axis295of sheath294. In use, after sheath294and segment298has been advanced into an initial position, e.g., transseptally through the atrial septum AS and within the left atrium LA of a patient's heart as shown inFIG.24B, the general trajectory angle Ψ may be defined by segment298of sheath294such that deployment catheter276, once advanced distally of sheath294, is directed generally towards the targeted tissue region such as the pulmonary vein ostia310. With hood210deployed and positioned generally over the targeted tissue region, the steerable segment of deployment catheter276may be articulated, e.g., at an angle Φ, to further direct hood210upon the targeted tissue. The combination of general steering (or course steering) of sheath294with the articulation (or fine steering) of deployment catheter276may be utilized to effectively articulate hood210upon any desired region of tissue. Moreover, navigation may be effective when angle Ψ>Φ, although this is not necessary to effectively articulate hood210.

Aside from steering in the deployment catheter and/or sheath, various alternatives may also incorporate steerable hood features either independently or in various combinations with any of the catheter and/or sheath articulation mechanisms described herein. An example is illustrated in the perspective views ofFIGS.25A and25Bwhich show a steerable hood210having one or more steerable members or leaflets312, which may also function to provide structural support to the deployed hood210. Each member or leaflet312may be integrated with the hood210material or overlaid atop and otherwise attached to hood210. Member or leaflet312are illustrated as closed looped members which extend distally over hood210, but other atraumatic configurations may be employed. A proximal end of one or more leaflets312may extend proximally through deployment catheter276such that a user may manipulate the leaflets312by pulling and/or pushing the leaflet312proximal end to effect a corresponding result along hood210. As illustrated inFIG.25B, upon pulling a proximal end of one leaflet312, hood210may be slanted to an angle Φ, which may be defined as the angle between an axis311transverse to deployment catheter276and an axis313transverse to hood210. By pulling/pushing one or more leaflet struts simultaneously, the hood210can be steered and slanted along different planes. Such leaflet struts312can be made from various materials, e.g., nitinol, stainless steel, tungsten, elgiloy, etc.

FIG.25Cshows a side view of steerable hood210directed against a tissue surface316for visualization and/or treatment. As described above, sheath294may be steered to provide a general trajectory and an angle Ψ to direct the deployment catheter276generally towards the target tissue surface316. Once deployed hood210has been brought into proximity, the leaflet struts312may be actuated to slant or tilt hood210at an angle Φ such that the distal end of hood210may be placed directly in apposition against the tissue surface316to facilitate sealing, visualization, and tissue treatment.

FIGS.26A and26Bshow perspective and side views, respectively, of another variation of a steerable hood210which utilizes a pair of struts320,321which may be positioned along the walls of hood210and are connected to a circumferential member318providing support to the distal circumferential edge of hood210. Similarly to the leaflet struts above, the steering struts320,321may be pulled and/or pushed alternately to slant hood210at a desired angle.

In yet another embodiment, articulation of hood210may be affected passively by having a conformable lip322positioned to extend distally about a circumference of hood210, as shown in the perspective view ofFIG.27A. The conformable lip322can be made from an inflatable balloon shaped into a donut or toroidal shape defining a passage321therethrough and attached to the distal end of hood210. The balloon can be (but is not limited to) materials such as polyurethane, silicone, rubber latex, PET (polyethylene terephthalate), etc. The conformable lip322can also be made from an extrusion of soft conformable materials such as polyether/polyester sponges or polystyrene (Styrofoam) and may also be transparent.

In use, as hood210is advanced towards the targeted tissue region, as shown inFIG.27B, conformable lip322may be inflated or otherwise expanded. As the hood210is pressed (possibly at an angle) against target tissue, as indicated inFIG.27C, conformable lip322may deform against the anatomy of the tissue surface to facilitate sealing and visualization.

Turning now to the perspective assembly view ofFIG.28, another variation of an articulatable deployment catheter276is shown which comprises a distal steerable section324and a proximal steerable section326located proximally of the distal steerable section324. An intervening link347may couple the sections324,326to one another and provide a terminal link to which one or more pull wires may be attached in controlling one or both sections. The distal steerable section324may utilize individual links340which allow for the section324to be articulated in a variety of different directions and angles, e.g., four-way steering, to enable omni-direction articulation. The individual links340may accordingly utilize a body member341having a pair of yoke members343positioned opposite to one another and extending distally from the body member341and each defining an opening. A pair of pins345may each extend radially in opposing directions from body member341and in a perpendicular plane relative to a plane defined by the yoke members343.

Turning to the perspective assembly view ofFIG.29A, the pins345of each link340may be pivotably received by the yoke members343of an adjacent link340such that the pins345and yoke members343are joined in an alternating manner. This alternating connection allows for the serially aligned links340to be articulated omni-directionally.

The links328of the proximal steering section326may be seen in detail in the perspective view ofFIG.28. These links328may also comprise a pair of yoke members331positioned opposite to one another and extending distally from bodey member329. However, the pins333may extend radially in opposing directions while remaining in the same plane as that defined by yoke members331. When joined together in series, as illustrated in the perspective detail view ofFIG.29B, each pin333of each link328may be pivotably received by the yoke members331of an adjacent link328. Yet when joined, the composite proximal steering section326may be constrained to bend planarly within a single plane relative to the rest of the deployment catheter.

The combined distal steerable section324and a proximal steerable section326results in a proximal steering section which can be articulated in a single plane to retroflex the entire distal assembly and a distal steering section which can then be articulated any number of directions, e.g., four-way steering, to access anatomical structures within the heart or any other lumen. The assembly may thus be used, e.g., to create circumferential lesions around the ostia of the pulmonary veins in the left atrium while the underlying tissue remains under direct visualization through the hood.

The operator may manipulate catheter276to position hood210on or around the ostia of the pulmonary veins in the left atrium LA. Once the accurate positioning of catheter276has been verified by real-time images captured through the imaging hood210, as described above, ablation through any number of instruments may be accomplished. As illustrated in the partial cross-sectional view ofFIG.30A, deployment catheter276is shown advanced transseptally across the atrial septum AS and into the left atrium LA. To access the ostia of the pulmonary veins, such as the left superior pulmonary vein ostium342, proximal steering section326may be articulated to first retroflex the distal assembly to bring hood210into proximity with ostium342. Distal steering section324may then be articulated to bring hood210into contact against the tissue surface. Once the appropriate location has been determined visually, as described above, the underlying tissue may be ablated344. As the entire circumference of ostium342is desirably ablated to adequately treat conditions such as atrial fibrillation, distal steering section324may be articulated to move hood210about the entire ostium342while ablating the tissue due to the omni-directional steering capability of steering section324while the curvature of proximal steering section326may be maintained, as shown inFIGS.30B and30C.

Once the ablation about a first ostium is completed, deployment catheter276may be repositioned by manipulating the catheter and/or adjusting the articulation of proximal steering section326, as illustrated inFIG.30D. Once hood210has been repositioned, e.g., proximate to the left superior pulmonary vein ostium346, the process may be repeated and the underlying tissue may be ablated348about the ostium346while utilizing the steering capabilities of both steering sections324,326, as shown in theFIGS.30E and30F.

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.