Delivery of biological compounds to ischemic and/or infarcted tissue

Abstract

The delivery of biological compounds to ischemic and/or infarcted tissue are described herein where such a system may include a deployment catheter and an attached imaging hood deployable into an expanded configuration. In use, the imaging hood is placed against or adjacent to a region of tissue to be imaged in a body lumen that is normally filled with an opaque bodily fluid such as blood. A translucent or transparent fluid, such as saline, can be pumped into the imaging hood until the fluid displaces any blood, thereby leaving a clear region of tissue to be imaged via an imaging element in the deployment catheter. Additionally, any number of therapeutic tools can also be passed through the deployment catheter and into the imaging hood for performing any number of procedures on the tissue for identifying, locating, and/or accessing ischemic and/or infarcted tissue.

Description

FIELD OF THE INVENTION

The present invention relates generally to medical devices used for accessing, visualizing, and/or treating regions of tissue within a body. More particularly, the present invention relates to methods and apparatus for locating and accessing ischemic and/or infracted tissue and for treating the tissue by delivering biologically active compounds within a patient heart.

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.

Thus, 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 provide instruments for therapeutic procedures upon the visualized tissue are desirable.

SUMMARY OF THE INVENTION

A tissue imaging and manipulation apparatus that may be utilized for procedures within a body lumen, such as the heart, in which visualization of the surrounding tissue is made difficult, if not impossible, by medium contained within the lumen such as blood, is described below. Generally, such a tissue imaging and manipulation apparatus comprises an optional delivery catheter or sheath through which a deployment catheter and imaging hood may be advanced for placement against or adjacent to the tissue to be imaged.

The deployment catheter may define a fluid delivery lumen therethrough as well as an imaging lumen within which an optical imaging fiber or assembly may be disposed for imaging tissue. When deployed, the imaging hood may be expanded into any number of shapes, e.g., cylindrical, conical as shown, semi-spherical, etc., provided that an open area or field is defined by the imaging hood. The open area is the area within which the tissue region of interest may be imaged. The imaging hood may also define an a traumatic contact lip or edge for placement or abutment against the tissue region of interest. Moreover, the distal end of the deployment catheter or separate manipulatable catheters may be articulated through various controlling mechanisms such as push-pull wires manually or via computer control

In operation, after the imaging hood has been deployed, fluid may be pumped at a positive pressure through the fluid delivery lumen until the fluid fills the open area completely and displaces any blood from within the open area. The fluid may comprise any biocompatible fluid, e.g., saline, water, plasma, Fluorinert™, etc., which is sufficiently transparent to allow for relatively undistorted visualization through the fluid. The fluid may be pumped continuously or intermittently to allow for image capture by an optional processor which may be in communication with the assembly.

One particular application for the tissue visualization system includes utilizing the system for detecting the presence and/or location of ischemic and/or infarcted tissue by visual inspection and/or measurement of one or more parameter of the tissue. Any number of physiologic parameters can be utilized to obtain measurements of the visualized tissue to detect the certain parameters, e.g., partial pressure values of oxygen (PO2) and carbon dioxide (PCO2); temperature differences between tissue regions; biomarkers indicative of injured tissue; electrical current and/or electrical potential differences through the tissue; variations in tissue surface hardness and deflection between tissue regions; etc.

Once the injured tissue region has been identified, a number of treatments may be utilized for injecting or infusing bioactive agents into or upon the tissue. Accordingly, a number of systems and methods for utilizing instruments to locate and/or access ischemic and/or infarcted tissue and to treat the tissue by delivering biologically active compounds may be utilized.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1A shows a side view of one variation of a tissue imaging apparatus during deployment from a sheath or delivery catheter.

FIG. 1B shows the deployed tissue imaging apparatus of FIG. 1A having an optionally expandable hood or sheath attached to an imaging and/or diagnostic catheter.

FIG. 1C shows an end view of a deployed imaging apparatus.

FIGS. 1D to 1F show the apparatus of FIGS. 1A to 1C with an additional lumen, e.g., for passage of a guidewire therethrough.

FIGS. 2A and 2B show one example of a deployed tissue imager positioned against or adjacent to the tissue to be imaged and a flow of fluid, such as saline, displacing blood from within the expandable hood.

FIG. 3A shows an articulatable imaging assembly which may be manipulated via push-pull wires or by computer control.

FIGS. 3B and 3C show steerable instruments, respectively, where an articulatable delivery catheter may be steered within the imaging hood or a distal portion of the deployment catheter itself may be steered.

FIGS. 4A to 4C show side and cross-sectional end views, respectively, of another variation having an off-axis imaging capability.

FIGS. 5A and 5B show examples of various visualization imagers which may be utilized within or along the imaging hood.

FIGS. 6A to 6C illustrate deployment catheters having one or more optional inflatable balloons or anchors for stabilizing the device during a procedure.

FIGS. 7A and 7B illustrate a variation of an anchoring mechanism such as a helical tissue piercing device for temporarily stabilizing the imaging hood relative to a tissue surface.

FIG. 7C shows another variation for anchoring the imaging hood having one or more tubular support members integrated with the imaging hood; each support members may define a lumen therethrough for advancing a helical tissue anchor within.

FIG. 8A shows an illustrative example of one variation of how a tissue imager may be utilized with an imaging device.

FIG. 8B shows a further illustration of a hand-held variation of the fluid delivery and tissue manipulation system.

FIGS. 9A to 9C illustrate an example of capturing several images of the tissue at multiple regions.

FIG. 10 shows a perspective view of the tissue visualization catheter visualizing the underlying tissue for the presence of ischemic and/or infarcted tissue.

FIGS. 11A and 11B show side and perspective views, respectively, of a variation of the tissue visualization catheter having a needle catheter for injecting a fluorescent dye into the underlying tissue to determine whether ischemic and/or infarcted tissue is present.

FIG. 12 shows a perspective view of a variation of the tissue visualization catheter having a single probe configured to obtain measurements of a variety of physiologic parameters for determining the presence and/or location of ischemic and/or infarcted tissue.

FIG. 13 shows a perspective view of another variation of the tissue visualization catheter having a multi-probe configuration to obtain measurements of a variety of physiologic parameters for determining presence and location of ischemic and/or infarcted tissue.

FIG. 14A shows a perspective view of a helical needle having a plurality of holes or openings along a surface of the needle body for delivery of bioactive substances into tissue

FIG. 14B shows a perspective view of the helical delivery needle to be advanced into the underlying tissue while under direct visualization.

FIG. 15 shows a perspective view of another variation of the visualization catheter having multiple helical delivery needles positioned circumferentially around a periphery of the hood.

FIGS. 16A and 16B illustrate perspective views of another variation where a laser probe, e.g., an optical fiber bundle coupled to a laser generator, may be inserted through the work channel of the tissue visualization catheter and activated for ablation treatment prior to delivery of bioactive substances into the ablated tissue.

FIG. 17 shows a cross sectional view of the heart illustrating the implantation of a deposited delivery of a bioactive substance, e.g., in the anterolateral myocardium of the left ventricle.

DETAILED DESCRIPTION OF THE INVENTION

A tissue-imaging and manipulation apparatus described below is able to provide real-time images in vivo of tissue regions within a body lumen such as a heart, which is filled with blood flowing dynamically therethrough and is also able to provide intravascular tools and instruments for performing various procedures upon the imaged tissue regions. Such an apparatus may be utilized for many procedures, e.g., facilitating trans-septal access to the left atrium, cannulating the coronary sinus, diagnosis of valve regurgitation/stenosis, valvuloplasty, atrial appendage closure, arrhythmogenic focus ablation, among other procedures. Details of tissue imaging and manipulation systems and methods which may be utilized with apparatus and methods described herein are described in U.S. patent application Ser. No. 11/259,498 filed Oct. 25, 2005 (U.S. Pat. Pub. No. 2006/0184048 A1), which is incorporated herein by reference in its entirety.

One variation of a tissue access and imaging apparatus is shown in the detail perspective views of FIGS. 1A to 1C. As shown in FIG. 1A, tissue imaging and manipulation assembly 10 may be delivered intravascularly through the patient's body in a low-profile configuration via a delivery catheter or sheath 14. 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 trans-septal procedure or septostomy. For procedures such as percutaneous valve repair and replacement, trans-septal access to the left atrial chamber of the heart may allow for larger devices to be introduced into the venous system than can generally be introduced percutaneously into the arterial system.

When the imaging and manipulation assembly 10 is ready to be utilized for imaging tissue, imaging hood 12 may be advanced relative to catheter 14 and deployed from a distal opening of catheter 14, as shown by the arrow. Upon deployment, imaging hood 12 may be unconstrained to expand or open into a deployed imaging configuration or may form a non-inflatable barrier or membrane, as shown in FIG. 1B. Imaging hood 12 may be fabricated from a variety of pliable or conformable biocompatible material including but not limited to, e.g., polymeric, plastic, or woven materials. One example of a woven material is Kevlar® (E. I. du Pont de Nemours, Wilmington, Del.), which is an aramid and which can be made into thin, e.g., less than 0.001 in., materials which maintain enough integrity for such applications described herein. Moreover, the imaging hood 12 may be fabricated from a translucent or opaque material and in a variety of different colors to optimize or attenuate any reflected lighting from surrounding fluids or structures, i.e., anatomical or mechanical structures or instruments. In either case, imaging hood 12 may be fabricated into a uniform structure or a scaffold-supported structure, in which case a scaffold made of a shape memory alloy, such as Nitinol, or a spring steel, or plastic, etc., may be fabricated and covered with the polymeric, plastic, or woven material.

Imaging hood 12 may be attached at interface 24 to a deployment catheter 16 which may be translated independently of deployment catheter or sheath 14. Attachment of interface 24 may be accomplished through any number of conventional methods. Deployment catheter 16 may define a fluid delivery lumen 18 as well as an imaging lumen 20 within which an optical imaging fiber or assembly may be disposed for imaging tissue. When deployed, imaging hood 12 may expand into any number of shapes, e.g., cylindrical, conical as shown, semi-spherical, etc., provided that an open area or field 26 is defined by imaging hood 12. The open area 26 is the area within which the tissue region of interest may be imaged. Imaging hood 12 may also define an atraumatic contact lip or edge 22 for placement or abutment against the tissue region of interest. Moreover, the diameter of imaging hood 12 at its maximum fully deployed diameter, e.g., at contact lip or edge 22, is typically greater relative to a diameter of the deployment catheter 16 (although a diameter of contact lip or edge 22 may be made to have a smaller or equal diameter of deployment catheter 16). For instance, the contact edge diameter may range anywhere from 1 to 5 times (or even greater, as practicable) a diameter of deployment catheter 16. FIG. 1C shows an end view of the imaging hood 12 in its deployed configuration. Also shown are the contact lip or edge 22 and fluid delivery lumen 18 and imaging lumen 20.

The imaging and manipulation assembly 10 may additionally define a guidewire lumen therethrough, e.g., a concentric or eccentric lumen, as shown in the side and end views, respectively, of FIGS. 1D to 1F. The deployment catheter 16 may define guidewire lumen 19 for facilitating the passage of the system over or along a guidewire 17, which may be advanced intravascularly within a body lumen. The deployment catheter 16 may then be advanced over the guidewire 17, as generally known in the art.

In operation, after imaging hood 12 has been deployed, as in FIG. 1B, and desirably positioned against the tissue region to be imaged along contact edge 22, the displacing fluid may be pumped at positive pressure through fluid delivery lumen 18 until the fluid fills open area 26 completely and displaces any fluid 28 from within open area 26. The displacing fluid flow may be laminarized to improve its clearing effect and to help prevent blood from re-entering the imaging hood 12. 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 area 26 and which is subsequently passed into and through the heart and the patient body.

As seen in the example of FIGS. 2A and 2B, deployment catheter 16 may be manipulated to position deployed imaging hood 12 against or near the underlying tissue region of interest to be imaged, in this example a portion of annulus A of mitral valve MV within the left atrial chamber. As the surrounding blood 30 flows around imaging hood 12 and within open area 26 defined within imaging hood 12, as seen in FIG. 2A, the underlying annulus A is obstructed by the opaque blood 30 and is difficult to view through the imaging lumen 20. The translucent fluid 28, such as saline, may then be pumped through fluid delivery lumen 18, intermittently or continuously, until the blood 30 is at least partially, and preferably completely, displaced from within open area 26 by fluid 28, as shown in FIG. 2B.

Although contact edge 22 need not directly contact the underlying tissue, it is at least preferably brought into close proximity to the tissue such that the flow of clear fluid 28 from open area 26 may be maintained to inhibit significant backflow of blood 30 back into open area 26. Contact edge 22 may also be made of a soft elastomeric material such as certain soft grades of silicone or polyurethane, as typically known, to help contact edge 22 conform to an uneven or rough underlying anatomical tissue surface. Once the blood 30 has been displaced from imaging hood 12, an image may then be viewed of the underlying tissue through the clear fluid 30. This image may then be recorded or available for real-time viewing for performing a therapeutic procedure. The positive flow of fluid 28 may be maintained continuously to provide for clear viewing of the underlying tissue. Alternatively, the fluid 28 may be pumped temporarily or sporadically only until a clear view of the tissue is available to be imaged and recorded, at which point the fluid flow 28 may cease and blood 30 may be allowed to seep or flow back into imaging hood 12. This process may be repeated a number of times at the same tissue region or at multiple tissue regions.

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 assembly 40 in FIG. 3A, one or more push-pull wires 42 may be routed through deployment catheter 16 for steering the distal end portion of the device in various directions 46 to desirably position the imaging hood 12 adjacent to a region of tissue to be visualized. Depending upon the positioning and the number of push-pull wires 42 utilized, deployment catheter 16 and imaging hood 12 may be articulated into any number of configurations 44. The push-pull wire or wires 42 may be articulated via their proximal ends from outside the patient body manually utilizing one or more controls. Alternatively, deployment catheter 16 may be articulated by computer control, as further described below.

Additionally or alternatively, an articulatable delivery catheter 48, 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 catheter 16 and into imaging hood 12. With a distal portion of articulatable delivery catheter 48 within imaging hood 12, the clear displacing fluid may be pumped through delivery catheter 48 or deployment catheter 16 to clear the field within imaging hood 12. As shown in FIG. 3B, the articulatable delivery catheter 48 may be articulated within the imaging hood to obtain a better image of tissue adjacent to the imaging hood 12. Moreover, articulatable delivery catheter 48 may be articulated to direct an instrument or tool passed through the catheter 48, as described in detail below, to specific areas of tissue imaged through imaging hood 12 without having to reposition deployment catheter 16 and re-clear the imaging field within hood 12.

Alternatively, rather than passing an articulatable delivery catheter 48 through the deployment catheter 16, a distal portion of the deployment catheter 16 itself may comprise a distal end 49 which is articulatable within imaging hood 12, as shown in FIG. 3C. Directed imaging, instrument delivery, etc., may be accomplished directly through one or more lumens within deployment catheter 16 to specific regions of the underlying tissue imaged within imaging hood 12.

Visualization within the imaging hood 12 may be accomplished through an imaging lumen 20 defined through deployment catheter 16, 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 catheter 16. Alternatively or additionally, an articulatable imaging assembly having a pivotable support member 50 may be connected to, mounted to, or otherwise passed through deployment catheter 16 to provide for visualization off-axis relative to the longitudinal axis defined by deployment catheter 16, as shown in FIG. 4A. Support member 50 may have an imaging element 52, e.g., a CCD or CMOS imager or optical fiber, attached at its distal end with its proximal end connected to deployment catheter 16 via a pivoting connection 54.

If one or more optical fibers are utilized for imaging, the optical fibers 58 may be passed through deployment catheter 16, as shown in the cross-section of FIG. 4B, and routed through the support member 50. The use of optical fibers 58 may provide for increased diameter sizes of the one or several lumens 56 through deployment catheter 16 for 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 fibers 58, in which case the electronic imager may be positioned in the distal portion of the deployment catheter 16 with electric wires being routed proximally through the deployment catheter 16. 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 farther detail. Support member 50 may be pivoted via connection 54 such that the member 50 can be positioned in a low-profile configuration within channel or groove 60 defined in a distal portion of catheter 16, as shown in the cross-section of FIG. 4C. During intravascular delivery of deployment catheter 16 through the patient body, support member 50 can be positioned within channel or groove 60 with imaging hood 12 also in its low-profile configuration. During visualization, imaging hood 12 may be expanded into its deployed configuration and support member 50 may be deployed into its off-axis configuration for imaging the tissue adjacent to hood 12, as in FIG. 4A. Other configurations for support member 50 for off-axis visualization may be utilized, as desired.

FIG. 5A shows a partial cross-sectional view of an example where one or more optical fiber-bundles 62 may be positioned within the catheter and within imaging hood 12 to provide direct in-line imaging of the open area within hood 12. FIG. 5B shows another example where an imaging element 64 (e.g., CCD or CMOS electronic imager) may be placed along an interior surface of imaging hood 12 to provide imaging of the open area such that the imaging element 64 is off-axis relative to a longitudinal axis of the hood 12. The off-axis position of element 64 may provide for direct visualization and uninhibited access by instruments from the catheter to the underlying tissue during treatment.

To facilitate stabilization of the deployment catheter 16 during a procedure, one or more inflatable balloons or anchors 76 may be positioned along the length of catheter 16, as shown in FIG. 6A. For example, when utilizing a trans-septal approach across the atrial septum AS into the left atrium LA, the inflatable balloons 76 may be inflated from a low-profile into their expanded configuration to temporarily anchor or stabilize the catheter 16 position relative to the heart H. FIG. 6B shows a first balloon 78 inflated while FIG. 6C also shows a second balloon 80 inflated proximal to the first balloon 78. In such a configuration, the septal wall AS may be wedged or sandwiched between the balloons 78, 80 to temporarily stabilize the catheter 16 and imaging hood 12. A single balloon 78 or both balloons 78, 80 may be used. Other alternatives may utilize expandable mesh members, malecots, or any other temporary expandable structure. After a procedure has been accomplished, the balloon assembly 76 may be deflated or re-configured into a low-profile for removal of the deployment catheter 16.

To further stabilize a position of the imaging hood 12 relative to a tissue surface to be imaged, various anchoring mechanisms may be optionally employed for temporarily holding the imaging hood 12 against 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 catheter 82 having at least one instrument lumen and an optional visualization lumen may be delivered through deployment catheter 16 and into an expanded imaging hood 12. As the imaging hood 12 is brought into contact against a tissue surface T to be examined, an anchoring mechanisms such as a helical tissue piercing device 84 may be passed through the tool delivery catheter 82, as shown in FIG. 7A, and into imaging hood 12.

The helical tissue engaging device 84 may 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 device 84 may be pulled proximally relative to deployment catheter 16 while the deployment catheter 16 and imaging hood 12 are pushed distally, as indicated by the arrows in FIG. 7B, to gently force the contact edge or lip 22 of imaging hood against the tissue T. The positioning of the tissue engaging device 84 may be locked temporarily relative to the deployment catheter 16 to ensure secure positioning of the imaging hood 12 during a diagnostic or therapeutic procedure within the imaging hood 12. After a procedure, tissue engaging device 84 may 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 catheter 16 may be repositioned to another region of tissue where the anchoring process may be repeated or removed from the patient body. The tissue engaging device 84 may also be constructed from other known tissue engaging devices such as vacuum-assisted engagement or grasper-assisted engagement tools, among others.

Although a helical anchor 84 is 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 catheter 82 may be omitted entirely and the anchoring device may be delivered directly through a lumen defined through the deployment catheter 16.

In another variation where the tool delivery catheter 82 may be omitted entirely to temporarily anchor imaging hood 12, FIG. 7C shows an imaging hood 12 having one or more tubular support members 86, e.g., four support members 86 as shown, integrated with the imaging hood 12. The tubular support members 86 may define lumens therethrough each having helical tissue engaging devices 88 positioned within. When an expanded imaging hood 12 is to be temporarily anchored to the tissue, the helical tissue engaging devices 88 may be urged distally to extend from imaging hood 12 and each may be torqued from its proximal end to engage the underlying tissue T. Each of the helical tissue engaging devices 88 may be advanced through the length of deployment catheter 16 or they may be positioned within tubular support members 86 during the delivery and deployment of imaging hood 12. Once the procedure within imaging hood 12 is finished, each of the tissue engaging devices 88 may be disengaged from the tissue and the imaging hood 12 may be repositioned to another region of tissue or removed from the patient body.

An illustrative example is shown in FIG. 8A of a tissue imaging assembly connected to a fluid delivery system 90 and to an optional processor 98 and image recorder and/or viewer 100. The fluid delivery system 90 may generally comprise a pump 92 and an optional valve 94 for controlling the flow rate of the fluid into the system. A fluid reservoir 96, fluidly connected to pump 92, may hold the fluid to be pumped through imaging hood 12. An optional central processing unit or processor 98 may be in electrical communication with fluid delivery system 90 for controlling flow parameters such as the flow rate and/or velocity of the pumped fluid. The processor 98 may also be in electrical communication with an image recorder and/or viewer 100 for directly viewing the images of tissue received from within imaging hood 12. Imager recorder and/or viewer 100 may also be used not only to record the image but also the location of the viewed tissue region, if so desired.

Optionally, processor 98 may also be utilized to coordinate the fluid flow and the image capture. For instance, processor 98 may be programmed to provide for fluid flow from reservoir 96 until 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 recorder 100 and pump 92 may be automatically stopped or slowed by processor 98 to 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. 8B shows a further illustration of a hand-held variation of the fluid delivery and tissue manipulation system 110. In this variation, system 110 may have a housing or handle assembly 112 which can be held or manipulated by the physician from outside the patient body. The fluid reservoir 114, shown in this variation as a syringe, can be fluidly coupled to the handle assembly 112 and actuated via a pumping mechanism 116, e.g., lead screw. Fluid reservoir 114 may be a simple reservoir separated from the handle assembly 112 and fluidly coupled to handle assembly 112 via one or more tubes. The fluid flow rate and other mechanisms may be metered by the electronic controller 118.

Deployment of imaging hood 12 may be actuated by a hood deployment switch 120 located on the handle assembly 112 while dispensation of the fluid from reservoir 114 may be actuated by a fluid deployment switch 122, which can be electrically coupled to the controller 118. Controller 118 may also be electrically coupled to a wired or wireless antenna 124 optionally integrated with the handle assembly 112, as shown in the figure. The wireless antenna 124 can be used to wirelessly transmit images captured from the imaging hood 12 to a receiver, e.g., via Bluetooth® wireless technology (Bluetooth SIG, Inc., Bellevue, Wash.), RF, etc., for viewing on a monitor 128 or for recording for later viewing.

Articulation control of the deployment catheter 16, or a delivery catheter or sheath 14 through which the deployment catheter 16 may be delivered, may be accomplished by computer control, as described above, in which case an additional controller may be utilized with handle assembly 112. In the case of manual articulation, handle assembly 112 may incorporate one or more articulation controls 126 for manual manipulation of the position of deployment catheter 16. Handle assembly 112 may also define one or more instrument ports 130 through which a number of intravascular tools may be passed for tissue manipulation and treatment within imaging hood 12, as described further below. Furthermore, in certain procedures, fluid or debris may be sucked into imaging hood 12 for evacuation from the patient body by optionally fluidly coupling a suction pump 132 to handle assembly 112 or directly to deployment catheter 16.

As described above, fluid may be pumped continuously into imaging hood 12 to 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 hood 12. FIGS. 9A to 9C illustrate an example of capturing several images of the tissue at multiple regions. Deployment catheter 16 may be desirably positioned and imaging hood 12 deployed 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 hood 12 may be optionally anchored to the tissue, as described above, and then cleared by pumping the imaging fluid into the hood 12. Once sufficiently clear, the tissue may be visualized and the image captured by control electronics 118. The first captured image 140 may be stored and/or transmitted wirelessly 124 to a monitor 128 for viewing by the physician, as shown in FIG. 9A.

The deployment catheter 16 may be then repositioned to an adjacent portion of mitral valve MV, as shown in FIG. 9B, where the process may be repeated to capture a second image 142 for viewing and/or recording. The deployment catheter 16 may again be repositioned to another region of tissue, as shown in FIG. 9C, where a third image 144 may 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 catheter 16 and imaging hood 12 is 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 hood 12 until the tissue is to be imaged, where the imaging hood 12 may be cleared, as above.

As mentioned above, when the imaging hood 12 is 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 hood 12 at a positive pressure or it may be pumped under computer control for slowing or stopping the fluid flow into the hood 12 upon detection of various parameters or until a clear image of the underlying tissue is obtained. The control electronics 118 may also be programmed to coordinate the fluid flow into the imaging hood 12 with various physical parameters to maintain a clear image within imaging hood 12.

Detail examples and descriptions of a visualization catheter device and system which may be utilized herein are shown and described in further detail in U.S. patent application Ser. No. 11/259,498 filed Oct. 25, 2005, which has been incorporated herein above in its entirety.

One particular application for the tissue visualization system includes utilizing the system for detecting the presence and/or location of ischemic and/or infarcted tissue by visual inspection and/or measurement of one or more parameter of the tissue. Any number of physiologic parameters can be utilized to obtain measurements of the visualized tissue to detect the certain parameters, e.g., partial pressure values of oxygen (PO2) and carbon dioxide (PCO2); temperature differences between tissue regions; biomarkers indicative of injured tissue; electrical current and/or electrical potential differences through the tissue; variations in tissue surface hardness and deflection between tissue regions; etc.

One method for detecting the ischemic and/or infarcted tissue is by visual inspection alone. As shown in the perspective view of FIG. 10, with hood 12 placed over a tissue region T to be inspected, transparent displacement fluid 150 may be infused into the hood 12 and the underlying tissue may be visually inspected via imaging element 64. In determining the presence and/or location of the affected tissue, the user may directly visualize the tissue surface via the visualization catheter and ascertain, e.g., the colors, intensities, and patterns of appearance. Accordingly, regions of healthy and diseased tissue may be identified. Such physical parameters are generally known to one of skill in the art as indicated in various clinical-pathologic correlation studies.

Another method for detecting certain tissue conditions may incorporate the use of fluorescent compounds injected into the tissue being visually inspected to enhance any contrasts in the tissue appearance. As shown in the respective side and perspective views of FIGS. 11A and 11B, with hood 12 placed against the tissue region T to be inspected and the hood open area purged of blood, hollow piercing needle 160 may be advanced through deployment catheter 16 and into the underlying tissue T to penetrate at least partially into the tissue to directly administer a fluorescent chemical dye, e.g., indocyanin green. Alternatively, piercing needle 160 may be advanced against the tissue surface and simply drip the fluorescent dye onto or over the tissue surface. In yet another alternative, the fluorescent chemical dye may be systemically administered to the patient via an intravenous route. When the fluorescent dye has been absorbed by the tissue region T to be inspected, the tissue may exhibit a visual appearance which is indicative of certain physiological characteristics. For instance, the dyed tissue region may exhibit different patterns of variously fluorescing regions of tissue which may be indicative of tissue health, e.g., healthy, perfused tissue; ischemic tissue; infarcted tissue, necrotic tissue, etc.

The intensity and pattern of fluorescence may be observed directly by the user without image processing. Alternatively, imaging element 64 (which may be optionally filtered) may be in communication with signal processor 162 which may take the images and process them for analysis of the emitted wavelength distribution. The emitted wavelength distribution may be correlated to determine the physiologic characteristics of the tissue and the resulting image may be displayed upon a monitor 164 for user evaluation.

Another variation for determining tissue condition may include the use of a sensor probe 170 advanced into contact against the tissue surface T while under visualization from imaging element 64, as shown in FIG. 12. Sensor probe 170 may be used to measure physiologic data such as local tissue concentrations of the partial pressure values of oxygen (PO2) and/or carbon dioxide (PCO2) within the tissue region T. This data may be analyzed by processor 162 to extrapolate the locations of tissue having relatively higher PO2 values and/or lower PCO2 values which are indicative of well-perfused (and healthy) tissue. Conversely, regions with relatively lower PO2 and/or higher PCO2 values may indicate poorly-perfused and presumably ischemic and/or infarcted tissue. The measured concentration values of PO2 and/or PCO2 may be processed 162 for visual representation 164 to and evaluation by the user, as illustrated by the concentration profile 172 as measured by probe 170.

Aside from PO2 and PCO2 concentration measurement, sensor probe 170 may be additionally or alternatively configured to detect tissue temperature values as well. From local measured tissue temperatures as well as from the known temperature of the local perfusate, the user may extrapolate regions of the tissue T having relatively higher temperature values, which may be indicative of tissue having higher perfusion and metabolic activity (and presumably increased viability). Conversely, regions of tissue with relatively lower temperature values may be indicative of tissue having lower perfusion and metabolic activity (and presumably lowered viability), thus possibly indicating ischemic and/or infarcted tissue regions. The temperature measurements may also be processed 162 for visual representation 164, as illustrated by the temperature profile 174 as measured by probe 170.

FIG. 13 illustrates a perspective view of a variation of hood 12 having one or more sensor probes 180 which are located circumferentially about the periphery of hood 12. Several sensor probes 180 may be uniformly (or non-uniformly) placed around the hood 12 circumference such that when hood 12 contacts the tissue region T to be inspected, multiple measurements or a greater region of the tissue may be interrogated. Each of the sensor probes 180 may be configured for measuring PO2/PCO2 and/or temperature as well. Moreover, the measured data may be processed 162 to generate a concentration profile 182 and/or temperature profile 184, as above.

The sensor probe(s) in FIG. 12 and/or FIG. 13 may also be configured to detect other tissue parameters besides concentration and temperature. For instance, yet another variation includes utilizing the sensor probes for detecting the presence of certain biomarkers which are typically indicative of tissue injury, and presumably the presence of ischemic and/or infarcted tissue. In such a variation, one or more biochemical sensor probe(s) may be utilized to measure the presence of certain chemical substances. Typically, damaged tissues release unique chemical substances. In the case of myocardial tissue, damaged cardiac muscles release troponin T, I, and C; creatine phosphokinase; MB fraction (CKMB); myoglobin; and lactate dehydrogenase (LDH). By quantitatively measuring the concentrations of one or more of these biochemical markers, processor 162 may be used to map the location and degree of injury within the tissue.

In yet another variation of FIG. 12 and/or FIG. 13, sensor probe(s) may be configured to measure electrical current in the interrogated tissue region T. The pathologic physiologic changes induced by ischemia and infarction may be evident in the current level measured within injured tissue. For example, several weeks after myocardial tissue experiences infarction, the cardiac muscle undergoes liquefactive necrosis, remodeling, and ultimately scar formation. Scar tissue, comprised primarily of fibroblasts and collagen, demonstrates diminished electrical conductivity secondary to increased impedance (relative to healthy myocardium). By electrically sampling levels of tissue impedance at several points across the region of interest, one may generate a map delineating regions of tissue ischemia, infarct in evolution, acute infarct, subacute infarct, and old infarct (scar).

In another variation of FIG. 12 and/or FIG. 13, sensor probe(s) may be configured to measure electrical potential differences in the interrogated tissue region T. As such, one or more electrical probe(s) or electrodes may be utilized for measurement of electrical potential difference. The presence of pathologic physiologic changes induced by ischemia and/or infarction may be evidenced in the voltages measured, e.g., via an electrocardiogram (ECG) within injured tissues. An ECG is a graphical representation of cardiac electrical activity depicting voltage (ordinate) as a function of time (abcissa). ECG measurements have long been utilized to diagnose cardiac pathology including ischemia (S-T segment elevation) and infarction (S-T segment depression, Q waves). Presumably, intracardiac voltage measurements may demonstrate findings correlating to traditional transcutaneous ECG data. By mapping voltage differences throughout the tissue of interest, one may generate a map delineating regions of tissue ischemia, acute infarct, subacute infarct, and old infarct.

In yet another variation of FIG. 12 and/or FIG. 13, sensor probe(s) may be configured to detect tissue hardness and deflection differences in the interrogated tissue region T. As such, one or more probe(s) may be configured as pressure-sensitive probes for measuring hardness (e.g., Rockwell, Vickers, durometer type, etc.) or force required to produce a given deflection in the tissue of interest. Several weeks after infarction, myocardial tissue becomes weakened secondary to coagulative necrosis. In fact, the patient may be at risk for ventricular rupture. After several more weeks, the necrotic tissue is replaced with fibroblasts (scar tissue) which, although non-contractile, provides relatively stable structural support for the moving ventricle. It is theorized that the complete but unscarred infarct may demonstrate increased compliance and decreased hardness relative to normal myocardial tissue. Similarly, the healed (scarred) old infarct is thought to demonstrate decreased compliance and increased hardness relative to normal myocardial tissue. By acquiring multiple measurements from the tissue surface of interest, a map delineating the hardness and extrapolated infarct ages and locations may be generated.

Once a region of ischemic and/or infarcted tissue has been identified using any of the modalities described above, the injured tissue may be repaired or improved, in one variation, by administering one or more bioactive substances into the affected tissue. One method for treating the injured tissue may utilize a hollow needle, such as piercing needle 160 shown above in FIG. 11A, advanced into the tissue through hood 12 while under direct visualization. Another variation may utilize helical delivery needle 190, as shown in the perspective view of FIG. 14A. A hollow helical delivery needle 190 may be positioned upon elongate member 192 and it may also define a plurality of openings 194 along its surface through which one or more bioactive substances may be infused. In use, as shown in the perspective view of FIG. 14B, once the tissue region T of interest is identified, the helical delivery needle 190 may be gently twisted and advanced into the tissue. Once partially or fully embedded, bioactive chemicals may be infused within the tissue via the openings 194 in the needle 190. In another variation, rather than utilizing a single helical delivery needle, multiple delivery needles 190 may be positioned to extend along support struts/elongate members 200 along hood 12 and extend distally past the hood 12 for advancement into the underlying tissue, as shown in the perspective view of FIG. 15.

In yet another alternative for treating tissue regions identified as potentially ischemic and/or infarcted, a laser catheter may be utilized while under direct visualization of the tissue region of interest. FIGS. 16A and 16B illustrate perspective views where a laser probe or fiber 210, e.g., an optical fiber bundle coupled to a laser generator, may be inserted through the work channel of the tissue visualization catheter. When actuated, laser energy 212 may be channeled through probe 210 and applied to the underlying tissue at different angles to form a variety of lesion patterns. Further examples of laser or ablation probes are described in detail in U.S. patent application Ser. No. 11/775,819 filed Jul. 10, 2007, which is incorporated herein by reference in its entirety.

As the laser energy 212 is highly focused with intense energy to precisely ablate small quantities of tissue, the laser probe 210 may be used to perforate the tissue surface and/or deeper layers. Various bioactive chemicals may then be infused through hood 12 or through a catheter and directly into the tissue via the perforations. Alternatively, the tissue may be perforated during or after the various bioactive chemicals have been infused into the tissue. In yet another alternative, the tissue may be simply revascularized with the laser treatment and the infusion of bioactive chemicals may be omitted entirely, if so desired.

In yet another variation, a bioactive substance may be implanted into or near the injured tissue region. As shown in the partial cross-sectional view of the heart H, a bioactive substance 220 may be delivered and deposited directly into the tissue wall, e.g., in the anterolateral myocardium of the left ventricle, as shown in FIG. 17. The bioactive substance 220 may be delivered utilizing any number of delivery devices through hood 12 while under direct visualization, e.g., via a needle as described above. As shown, the deposited administration of a bioactive substance 220 within the tissue of interest may or may not be encapsulated for controlled release over time.

In treating the tissue with bioactive substances, any number of suitable materials may be delivered utilizing the devices and methods herein. For instance, bioactive substances for healing and/or regenerating functional tissue may include the use of stem cells, which are protean cells from which other specialized cell lines are formed. Most damaged tissues undergo a natural process of death, resorption, and scar formation. If the stem cells, e.g., from a patient's bone marrow, can be identified and isolated these may be transplanted into the damaged tissue of interest. Ideally, the specific stem cell line responsible for generating the tissue of interest is identified and transplanted. Preclinical studies have established that implantation of bone marrow mononuclear into ischemic limbs increased collateral vessel formation. Direct myocardial injection of, e.g., bone marrow cells, into the infarct border zone produced improved LV function and infarct tissue perfusion (Tse, et al. Lancet 2003, Jan. 4; 361 (9357): 47-9), which is incorporated herein by reference in its entirety. It follows that by utilizing any of the previously described devices for direct visualization to identify the location of damaged tissue (e.g. infracted myocardium) and any of the delivery systems to deposit the bioactive substances, one may deliver bone marrow cells (e.g. vascular progenitor cells) to stimulate angiogenesis for improved tissue perfusion and function as well as new intrinsic tissue formation (e.g. myogenesis).

Another example of a bioactive substance which may be infused into the identified injured tissue may include biologic substances which promote angiogenesis and subsequently improve local tissue perfusion and function. Vascular endothelial growth factor (VEGF) is an angiogenic factor regulating vascular endothelial cell migration, proliferation, and permeability. Fibroblast growth factor (FGF) induces microvascular endothelial cell growth and neovascularization. Similarly, pro-angiogenic cytokines including tumor necrosis factor alpha (TNF) and interleukin 8 (IL8), as well as the peptides SIKVAV (derived from laminin 1) and neuropeptide Y (NPY) have been shown to demonstrate similar effects.

Aside from administering bioactive agents, chemical irritants may also be delivered to tissue utilizing any of the methods and systems described herein to promote angiogenesis and improved tissue perfusion and function.

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.

Claims

1. A method of identifying a tissue region of interest for treatment, comprising: intravascularly advancing a deployment catheter towards the tissue region of interest through a vessel of a subject;expanding a non-inflatable barrier or membrane defining an open area in fluid communication with an environment external to the barrier or membrane and projecting distally from the deployment catheter against the tissue region of interest;urging a transparent fluid into the open area such that the fluid is retained within the open area when placed against or in proximity to the tissue region of interest and where the fluid is further displaced into the environment external to the barrier or membrane such that an opaque fluid is displaced from the open area;visualizing the tissue region of interest via a visualization element through the transparent fluid; andassessing at least one parameter of the tissue region.

2. The method of claim 1 wherein intravascularly advancing comprises advancing the deployment catheter into a chamber of a patient heart.

3. The method of claim 1 wherein expanding comprises self-expanding the barrier or membrane from a low-profile delivery configuration into an expanded deployed configuration.

4. The method of claim 1 wherein urging a transparent fluid comprises pumping the transparent fluid into the open area through a fluid delivery lumen defined through the deployment catheter.

5. The method of claim 4 wherein pumping the transparent fluid comprises urging saline, plasma, water, or perfluorinated liquid into the open area such that blood is displaced.

6. The method of claim 1 wherein visualizing comprises imaging the tissue region via an imaging element positioned within or adjacent to the expanded barrier or membrane.

7. The method of claim 1 wherein assessing comprises visually inspecting the tissue region for indications of ischemic and/or infarcted regions of tissue.

8. The method of claim 7 further comprising administering a fluorescent compound upon or into the tissue region prior to visually inspecting the tissue region.

9. The method of claim 8 wherein the fluorescent compound comprises indocyanin green.

10. The method of claim 1 wherein assessing comprises measuring a partial pressure of oxygen and/or carbon dioxide present in the tissue region.

11. The method of claim 1 wherein assessing comprises measuring a temperature of the tissue region.

12. The method of claim 1 wherein assessing comprises measuring for a presence of a biomarker indicative of tissue injury.

13. The method of claim 12 wherein the biomarker is selected from the group consisting of troponin T, troponin I, troponin C; creatine phosphokinase, MB fraction (CKMB), myoglobin, lactate dehydrogenase (LDH), and combinations thereof.

14. The method of claim 1 wherein assessing comprises detecting differences in electrical current and/or electrical potential in the tissue region.

15. The method of claim 1 wherein assessing comprises measuring relative tissue hardness and/or deflection over the tissue region.

16. The method of claim 1 further comprising identifying injured tissue based upon an assessment of the at least one parameter.

17. The method of claim 16 further comprising treating the injured tissue with a bioactive agent.

18. The method of claim 17 wherein treating comprises injecting or infusing the bioactive agent upon or into the injured tissue.

19. The method of claim 17 wherein the bioactive agent is selected from the group consisting of stem cells, vascular endothelial growth factor, fibroblast growth factor, pro-angiogenic cytokines, tumor necrosis factor alpha, interleukin 8, SIKVAV, and neuropeptide Y.

20. The method of claim 16 further comprising treating the injured tissue with a chemical irritant.

21. The method of claim 1 further comprising ablating the tissue region of interest based upon an assessment of the at least one parameter.