Abstract:
Disclosed are access devices that can be used to safely guide instruments, such as EP ablation catheters, to a therapy site such one within the pericardial space of the heart. The access devices include integrated visualization, illumination, stabilization, and safety features in a single platform that can, for example, more safely and efficiently identify and ablate several ventricular tachycardia (VT) locations on the left ventricle of the heart.

Description:
RELATED APPLICATIONS 
       [0001]    This patent application claims the benefit of U.S. Provisional Application No. 62/332,941 filed on May 6, 2016, entitled “Access Device for Cardiac Ablation,” which is incorporated herein by this reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This disclosure relates generally to medical devices and, in particular, devices for providing surgical access within the body of a patient. 
       BACKGROUND 
       [0003]    Existing medical devices and techniques for accessing the internal organs and anatomy of patients to treat medical conditions and deliver injectables are inadequate for many circumstances. For example, cardiologists would like to be able to perform arrhythmia treatments (e.g., mappings, diagnostics, and ablations) and to be able to deliver injectables to treat various atrial fibrillation and other heart conditions. However, many instances of such medical conditions are complex in nature and cannot be handled with existing endocardial catheters providing treatment on the inside of the heart. Specifically, for example, there are a host of sources of ventricular tachycardia that are on the outside of the heart, for example, on the left ventricle and right ventricle on the lateral wall. In addition, there is muscle on the outside of the heart that could be treated with various pharmaceuticals or other injectables. Being able to access the outside of the heart instead of, or in addition to, the inside of the heart, could enable better treatment outcomes, reduce patient risk, and provide other benefits in many circumstances. 
         [0004]    However, attempts to use existing endocardial devices to map, diagnose, and deliver therapies to the outside surface of the heart have revealed that those devices are not well suited for accessing the heart through the pericardium. The pericardium is a sac-like layer that surrounds and provides a protective, lubricated covering over the epicardium outside surface of the heart. The heart beats and otherwise moves within the pericardium, with the epicardium generally resting against the pericardium. Because of this contact, any device used within the pericardium must separate and navigate in the space between the pericardium and epicardium. Existing endocardial devices are not designed to create space, navigate, and remain stable in this context. During a procedure for example, the surface of the beating heart is in constant motion, beating  60 ,  70 , or more beats per minute. Existing devices are unable to navigate to and deliver treatments and injectables to precise locations within the pericardium and adjacent to a beating heart. 
         [0005]    Existing endocardial devices are also poorly suited for therapies on the outside of the heart because they rely on indirect imaging. For example, an endocardial procedure may involve a three-dimensional (3D) mapping system and/or fluoroscopy to provide images of the heart. However, such indirect imaging systems are ill-suited for navigating and treating the outside of the heart. Such systems do not enable adequate identification of many anatomical structures, such as fat pads, lesions, arteries, and vascular pads on the outside of the heart that often must be avoided. Similarly, it can be difficult to identify an ischemic patch for treatment using indirect visualization. 
         [0006]    Existing endocardial devices are particularly ill suited for ablation procedures on the outside surface of the heart. For example, existing 7 French electrophysiology (EP) ablation catheters and indirect imaging modalities have been used in such procedures. The procedures involved using endocardial EP ablation catheters within the pericardium on the epicardial surface of the beating heart and directing them around the surface of the heart by following their progress on 2D fluoroscopy images and/or mapping the area using conventional 3D mapping systems. Using these devices there is no pericardial space creation, no illumination of that space, and no direct visualization of the surface of the beating heart. The ablating end of the EP catheter is also not stabilized relative to the surface of the heart. There is also no way to directly visualize the precise location that is being considered for ablation to confirm that there are no epicardial coronary arteries or other anatomical structures that should not be ablated at the intended ablation site. 
         [0007]    There is a substantial need for one or more medical devices and methods for accessing the internal organs and anatomy of patients to treat medical conditions and deliver injectables in many circumstances. Such devices and methods are needed particularly in circumstances such as those that benefit from direct visualization, space creation, and/or stabilization within a space between two adjacent surfaces. 
       SUMMARY 
       [0008]    Disclosed are access devices that can be used to safely guide instruments, such as EP ablation catheters, to a therapy site, such one within the pericardial space of the heart. The access devices include integrated visualization, illumination, stabilization, and safety features in a single platform that can, for example, more safely and efficiently identify and ablate several ventricular tachycardia (VT) locations on the left ventricle of the heart. In addition, the access devices can include integrated ultrasound (e.g., an ultrasound transducer), for example, to determine epicardial wall thickness and/or to facilitate tissue determinations between vascularized tissue and ischemic tissue. 
         [0009]    The access devices disclosed herein facilitate improved medical techniques. For example, an exemplary access device can be introduced to the pericardium using a “dry” pericardial tap, micro-puncture technique, or modified Seldinger technique to establish guide wire access to the pericardial space. The access device can follow this guide wire into the pericardium. A camera in the access device can also provide visualization from insertion all the way to the heart or other organs for greater safety of administration. The device can be tapered to dilate the pericardium and allow the disclosed access device to enter the pericardial space. The device can elevate the neighboring pericardium with balloon inflation and/or using a hinged shell. Expanding a balloon or moving the hinged shell can help avoid damage to a phrenic nerve, improve visualization of the myocardium, and/or help stabilize the access device. An instrument, such as an EP ablation catheter, can then be introduced down the instrument channel of the access device to protrude out the distal end of the device. The camera in the access device can visualize the tip of the EP ablation catheter and confirm safe placement of the ablation tip before energizing the tip for ablation. The access device supporting the ablation catheter can additionally, or alternatively, connect to the beating surface of the heart using suction to further stabilize the ablation platform before treatment. The site can also be checked after treatment to confirm that no unexpected injury to the surface of the heart has occurred. 
         [0010]    The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0011]      FIG. 1  is a perspective view of an access device of one embodiment of the disclosed surgical access device. 
           [0012]      FIG. 2  is a top view of the access device of  FIG. 1 . 
           [0013]      FIG. 3  is a side view of the access device of  FIG. 1 . 
           [0014]      FIG. 4  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device. 
           [0015]      FIG. 5  is an alternate perspective view of the distal tip portion of  FIG. 4 . 
           [0016]      FIG. 6  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device. 
           [0017]      FIG. 7  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device. 
           [0018]      FIG. 8  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device with a deflated balloon. 
           [0019]      FIG. 9  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device with a deflated balloon. 
           [0020]      FIG. 10  is a perspective view of the distal tip portion of  FIG. 8  with an inflated balloon. 
           [0021]      FIG. 11  is a longitudinal sectional view of the distal tip portion of  FIG. 8  with an inflated balloon. 
           [0022]      FIG. 12  is a vertical sectional view of a distal tip portion of the surgical access device of  FIG. 6 . 
           [0023]      FIG. 13  is a vertical sectional view of a distal tip portion of the surgical access device of  FIG. 7 . 
           [0024]      FIG. 14  is a vertical sectional view of a distal tip portion of the surgical access device of  FIG. 8 . 
           [0025]      FIG. 15  is a perspective view of an access device of one embodiment of the disclosed surgical access device. 
           [0026]      FIG. 16  is a top view of the access device of  FIG. 15 . 
           [0027]      FIG. 17  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device. 
           [0028]      FIG. 18  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device. 
           [0029]      FIG. 19A  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device. 
           [0030]      FIG. 19B  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device. 
           [0031]      FIG. 20A  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device. 
           [0032]      FIG. 20B  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device. 
           [0033]      FIG. 21A  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device. 
           [0034]      FIG. 21B  is a perspective view of a distal tip portion of one embodiment of the disclosed surgical access device. 
           [0035]      FIG. 22  is a perspective view of the access device according to another embodiment. 
           [0036]      FIG. 23  is a perspective view of a distal tip portion of the embodiment of  FIG. 22 . 
           [0037]      FIG. 24  is a perspective view of a distal tip portion of the embodiment of  FIG. 22  with a guide wire inserted. 
           [0038]      FIG. 25  is a perspective view of a distal tip portion of the embodiment of  FIG. 22  with an ablation catheter inserted. 
           [0039]      FIG. 26  is a longitudinal sectional view of the distal tip portion of  FIG. 22  with the hinged shell raised. 
           [0040]      FIG. 27  is a perspective view of an alternative embodiment of the access device configured to have a low profile. 
           [0041]      FIG. 28  is a longitudinal sectional view of the distal tip portion of an access device having a projecting bump to guide an instrument at a downward angle towards tissue. 
       
    
    
     DETAILED DESCRIPTION 
       [0042]    The present invention now will be described more fully hereinafter with reference to specific embodiments of the invention. Indeed, the invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. As used in the specification, and in the appended claims, the singular forms “a”, “an”, “the”, include plural referents unless the context clearly dictates otherwise. The term “comprising” and variations thereof as used herein is used synonymously with the term “including” and variations thereof and are open, non-limiting terms. 
         [0043]    Embodiments of the invention provide access devices that can be used to safely guide instruments, such as EP ablation catheters, to a therapy site, such as one within the pericardial space of the heart. The access devices can be used with already-approved catheters and newly-developed catheters to enhance the capabilities of those catheters. In one example, an access device provides an exoskeleton through which an already-approved catheter can be inserted to effectively provide vision, lighting, stability, navigation, and/or articulation capabilities to the catheter. In addition, attributes of an access device can effectively lift the pericardium off the heart to create working space, illuminate the working space, and provide direct visualization of that working space. In one example, a physician is able to view the working end of an ablation catheter relative to a treatment location in the working space under direct video vision. The video vision can also show the relation of the catheter to nearby epicardial structures. Such visibility provides numerous benefits. For example, showing the epicardial coronary (or at least portions of them) and/or the left atrial appendage allows the user to determine the precise location of the treatment and avoid treating unintended areas. In many instances, the view provides sufficient confidence to allow treatment to commence without needing to pause the procedures for confirmation via fluoroscopy, which can significantly reduce the time and risks associated with the procedures. 
         [0044]    Referring to  FIGS. 1-3 , disclosed is an access device  10  for facilitating access, safety, stabilization, and visualization for cardiac ablation of the heart under the pericardium. The access device  10  generally includes a head portion  40 , a shaft  20 , and a handle portion  30 . 
         [0045]    It should be noted that although described in one embodiment as providing access to the heart for ablation, the access device may provide access to a range of tissue structures through varying pathways and for use with varying surgical instruments. For example, access could be provided to other organs, such as the liver, muscles, skeletal structures, etc. Some embodiments of the access device  10 , however, are best-suited for providing various combinations of visualization and access through small openings (e.g., 2 cm or less through the skin and pericardium) during surgical procedures, cardiology procedures, or EP cardiology catheterization laboratory procedures on the heart. 
         [0046]    As shown in  FIGS. 1-3 , the shaft  20  is attached to the handle portion  30  at its proximal end and to the head portion  40  at its distal end. The proximal end of the shaft  20  is configured to be manipulated from a position external to the patient&#39;s body (i.e., more “proximal” to the user). The distal end of the shaft  20  is sized and configured to insert through a relatively small opening in the patient&#39;s body, such as a 2 cm or smaller sub-xiphoid incision, or via percutaneous needle and guide wire access. 
         [0047]    As further shown in  FIGS. 12-14 , the shaft  20  defines a lumen that contains one or more channels extending longitudinally there through. Examples of channels that can extend through the lumen of the shaft  20  include, but are not limited to, an instrument channel  21 , a camera channel  22 , a camera flush line  23 , a balloon inflation channel  24 , and a guide wire channel  25 . In some cases, the lumen of the shaft  20  contains a distinct vacuum line channel, but in other cases, the lumen of the catheter shaft serves as the vacuum line channel. Preferably, the outer diameter of the shaft  20  is from 10 mm to 20 mm, including about 5, 10, 15, or 20 mm. The instrument channel  21  can extend proximally from the head portion  40 , through the shaft  20 , into the handle portion  30 , optionally terminating at an instrument portal  31  within the handle portion  30 . 
         [0048]    As further shown in  FIGS. 1-3 , the handle portion  40  optionally contains an instrument cradle  32  for affixing instrument controls to the handle portion  30 .  FIGS. 15-16  depict an access device  10  without an instrument cradle  32 . 
         [0049]    The access device  10  further contains a camera cable  33  extending proximally from a camera  41  in the head portion  40 , through the shaft  20 , and optionally into the handle portion  30 . The camera cable  33  preferably extends at least 6 feet beyond the handle portion  30  and can be connected to a light and/or electrical source for operation of the camera  22 . In one example, the camera cable includes optical fibers that transmit light from an external light source to the head portion  40 . The camera cable  33  can also be commutatively connected to a video processing unit. In some embodiments, the access device  10  comprises controls for the camera  41  in the handle portion  30 . Moreover, in some cases, the light and/or electrical source is housed within the handle portion  30 . 
         [0050]    The access device  10  can further contain one or more fluid lines, optionally extending proximally from the handle portion  40 , that are fluidly connected to the one or more channels extending longitudinally through the shaft  20 . For example, the access device  10  can include a balloon inflation line  34 , a vacuum line  35 , and/or a camera flush line  36 , fluidly connected to the balloon inflation channel  24 , vacuum line channel, and camera flush line  23 , respectively. Each of these lines can terminate at its proximal end in a port with a suitable attachment means, such as a Luer lock connector. 
         [0051]    As shown in  FIGS. 4-5 , the head portion  40  has a top and bottom (superior and inferior) orientation. The head portion  40  can include a balloon  42  on its top surface, positioned proximally to the camera  22 , fluidly connected to the balloon inflation line  34  and configured to elevate the pericardium and provide downward pressure towards the myocardium when inflated (see  FIG. 10 ). In some cases, the balloon extends about 180 degrees along the top circumference of the head portion  40 , for example as illustrated in  FIGS. 10 and 17 . 
         [0052]    The balloon  42  can be inflated to assist in moving tissue from the treatment region and from view of the camera  41  to increase direct visualization and depth of view. Lifting the immediate tissue can protect the tissue from the prescribed therapy. In some cases, the balloon  42  may inflate to approximately 3 times the diameter of the shaft&#39;s  20  outside diameter. In some cases, the inflated balloon  42  provides a directed downward force to stabilize the head portion  40 . The inflated balloon  42  can also assist with navigation about curvatures of tissue bodies. 
         [0053]    During certain diagnostic and therapeutic procedures stabilization of the catheter may be required to perform the prescribed procedures. As described above, a balloon  42  can be inflated to provide downward pressure and stabilize the access device and any instruments inserted therein. The balloon  42  is configured to be inflated with a predetermined amount of fluid to expand to a particular size and shape. In one example, the balloon  42  is in fluid communication with a syringe containing the predetermined volume of fluid. The syringe is depressed to inflate the balloon and withdrawn to deflate the balloon. In another embodiment, the inflation and deflation of the balloon is controlled by a pump configured to provide or withdrawal the predetermined amount of fluid. 
         [0054]    In some embodiments, the inflated balloon  42  provides a directed downward force to provide intimate contact between the heart tissue and an instrument (e.g., when sensing particular physical parameters such as temperature, thickness and density, ablating tissue, or injecting a substance). In some embodiments, the balloon is inflated an amount (e.g., with 3 ccm, 4 ccm, or another predetermined amount of air or saline) that provides sufficient stability of the access device  10  for treating a site without impeding navigation of the access device  10  within the pericardium. For example, the device can be advanced or retracted within the pericardial space without deflating the balloon  42 . The inflated balloon  42  secures the head portion  40  in whatever location it is in when the user stops navigating the access device  10 , which can simplify the procedure and significantly reduce the time required for a procedure involving multiple treatment sites. In alternative embodiments, the balloon  42  is configured to be deflated (at least partially) prior to the repositioning of the head portion  40  of the access device  20 . 
         [0055]    The configuration of the balloon  42  on the top surface of the access device  10  and/or overhanging the tip of the head portion  40  can facilitate stabilization of the access device  10 . In this example, when the balloon  42  is inflated in between two abutting surfaces (such as when the device is between the epicardium and pericardium), the lower surface of the head portion  40  of the access device  10  is pressed into whatever tissue it is against. The head portion  40  of the access device is stabilized adjacent to tissue that can be treated. Stabilizing the access device  10  in a position adjacent to tissue to be treated can provide advantages over stabilization mechanisms that create space around a head  40  of an access device  10  on all sides. 
         [0056]    Some embodiments include a balloon  42  configured to inflate about 180 degrees (e.g., 170 to 190 degrees) around the tip of the access device  10 . In particular, the opening from which the balloon  42  is configured to extend is an opening that extends about 180 degrees on the top surface of the access device  10 . Such a configuration has been found to reduce or minimize twisting or oscillation about the axis of the access device  10  while still allowing the lower surface of the access device  10  to contact tissue. Other opening sizes and shapes and balloon  42  configurations can cause the access device  10  to roll over on one side or the other and thus cause disorientation of the image produced by the camera  41 . 
         [0057]    Similarly, configuring the balloon  42  to extend beyond the tip of the access device  10 , e.g., by a 1, 2, 3, or more millimeters, can provide stabilization. The overhang of the balloon provides additional downward pressure on the tip of the access device  10  and can also create space beyond the tip by separating two surfaces (e.g., the epicardium and pericardium) from one another beyond the tip. This separation ahead of the access device  10  can enhance visualization and improve navigation by increasing the visual depth of field. 
         [0058]    Additionally, or alternatively, suction can be used to provide stabilization. A vacuum can be provided through an opening located proximally to the distal tip at the inferior surface. In some cases, this vacuum is applied to the instrument channel  21 . In these embodiments, a molded seal located internally within the head portion  40  can be used to provide a radial seal around the instrument to mitigate any vacuum leakage. Therefore, as shown in  FIG. 5 , the head portion  40  can also include a vacuum port  43  on its bottom surface, e.g., arranged on the opposing side of the head portion  40  from the balloon  42 , that is fluidly connected to the vacuum line  35 . The vacuum port  43  can consist of one hole (e.g., slot as shown in  FIG. 5 ) or a series of holes, configured to stabilize the head portion onto the surface of the heart when suction is applied to the vacuum line  35 . 
         [0059]    In some embodiments, the head portion  40  further includes a sensor. One example of a sensor is an ultrasound transducer (probe) used to determine the thickness and/or density of tissue. The data obtained from the ultrasound probe can be transmitted to a 3D mapping system, such as CARTO® 3 System, or ENSUE NAVX, e.g., to guide ablation and other treatments. In one example, an access device  10  includes one more metal bands configured to read a surface electrocardiogram to provide a wave form or mapping representing attributes of the tissue in the region to be treated. In one embodiment, an ablation catheter is configured with metal sensing bands for ultrasound sensing and/or a thermistor for sensing temperature. In another embodiment, a probe has piezoelectric crystals which are interconnected electronically and vibrate in response to an applied electric current. One embodiment uses a single crystal for real time depth interrogation and wall motion detection. This provides m-mode echocardiography, tracking tissue as it shrinks and expands in a single dimension. For example, viewing the data over time from left to right on a monitor, the user is able to see how the plane between the blood and the endocardium goes up and down with motion. This helps the user estimate the thickness of the wall and provides some indication of how the thickness changes with time. This provides a gross indicator of viability since there will generally not be a lot of m-mode motion of a segment of the wall over a scar but normal muscle should move in and out relatively normally. Using multiple crystals can provide additional advantages, for example, facilitating tissue characterization. Note that ultrasound capabilities can be used for ablation, injection, and other treatment application. For example, the thickness and tissue characterization information is useful in determining how long of a needle to use and how far into the heart to insert the needle during an injection. As another example, tissue characterization information is useful in ablation procedures to help users confirm that the ablation probe is targeting the right tissue. 
         [0060]    As shown in  FIGS. 4-10 , the head portion  40  also includes a camera  41  at or near its distal end oriented for visualization of instruments that extend distally from the head portion  40 . The camera  41  can contain both the optics and sensor necessary to capture an image. In some embodiments, only the optics of the camera  41  are located in the head portion  40 . For example, light from the optics can be transmitted fiber optically to a sensor that is located proximal to the head portion  40 . In some cases, the sensor is located in the handle portion  30 . 
         [0061]    In certain embodiments, the camera  41  uses a 0.9 mm to 1.6 mm diameter CMOS chip with optical fiber illumination permanently mounted in place. In certain embodiments, the camera  41  is oriented downward at an angle of 1 to 30 degrees relative to the longitudinal angle of the head portion  40  to provide an appropriate field of view. The camera  41  can use illumination fibers and/or light emitting diodes (LED&#39;s) equally spaced axially about the camera body. In one embodiment, illumination is provided through one or more fiber optic cables that provide light for the camera  41  from an external source with limited heat generated at the head  40  of the access device. For example, light generation can occur proximally (e.g., in a box on a nearby table). The use of fiber optic cables can also facilitate the provision of a greater amount of light to provide a brighter image from the camera  41  then may be possible using one or more LEDs. 
         [0062]    As shown in  FIGS. 6-10 , the head portion  40  also includes a camera flush port  46 , which can be used to pass saline across the camera lens in the event tissue or other matter obscures the field of view. 
         [0063]    The head portion  40  can also contain an instrument channel opening  44  at or near its distal end that is in fluid connection with the instrument channel  21 . In some embodiments, the instrument channel opening  44  is a single open lumen for which diagnostic and therapeutic instruments may pass. In some cases, this lumen has a diameter of approximately 2.0 to 4.0 mm, including about 2.5 mm to accommodate insertion of a 2.3 mm or 7 French instrument. 
         [0064]    As shown in  FIG. 8 , the head portion  40  can alternatively contain a guide wire opening  45  at or near its distal end that is in fluid connection with a guide wire channel  25 . In these embodiments, the instrument, such as an ablation catheter, does not extend distally substantially beyond the head portion  40 . In some cases, the ablation catheter instead contacts the myocardium through the vacuum port  43  ( FIG. 20B ). The guidewire opening  45  and/or lumen can have an inner diameter suitable for use with a 0.014 inch, 0.025 inch, or 0.035 inch guidewire. One advantage to this embodiment is a low profile tip that may not need an introducer. In addition, ablation energy can be directed only towards the tissue. 
         [0065]    As shown in  FIGS. 4-10 , the camera  41  is positioned above the instrument channel opening  44  or guide wire opening  45  relative to the orientation established by the balloon  42  (top) and vacuum port  43  (bottom). However, in some embodiments, the camera  41  is positioned adjacent to or below the instrument channel opening  44  or guide wire opening  45 . 
         [0066]    As can be seen when comparing  FIGS. 4, 6, 21A, and 21B , the head member can be either relatively tapered or relatively blunt. Tapering can be achieved in some cases by positioning the camera  41  either distal to ( FIG. 4 ), or proximal to ( FIG. 6 ), the instrument channel opening  44  or guide wire opening  45 . The distance between the camera  41  and the instrument channel opening  44  or guide wire opening  45  can therefore affect the amount of tapering. In some cases, the distance between the camera  41  and the instrument channel opening  44  or guide wire opening  45  is from 1 to 3 mm. 
         [0067]    The advantage to having the camera  41  positioned distal to the instrument channel opening  44  is that it can improve visualization of the ablation since the tip of the instrument can be closer to the camera. However, it may require a separate introducer sheath since the camera  41  would be ahead of the guidewire. 
         [0068]    In cases where the camera  41  is positioned distal to the instrument channel opening  44 , the inferior surface of the tapered tip is the only surface that instruments will contact as they exit the instrument channel opening  44 . In some cases, this surface slopes down with an angle of 1 to 30 degrees relative to the longitudinal angle of the head portion  40  such that the instrument is directed toward the surface of the heart with a contact point distal to the camera  41 . 
         [0069]    In some cases, the instruments have manual articulation and therefore can act as the articulating and guidance means. However, in other embodiments, and as shown in  FIG. 18 , the distal end of the shaft  20  can be articulated in at least one plane, preferably a horizontal plane. Therefore, the handle portion  30  optionally further contains controls  51 ,  52  for articulating the distal end of the shaft  20 . Control  53  is configured to lock the articulated distal end of the shaft in particular positions, e.g, far left, far right, center, etc. The articulation occurs primarily at the tip of the catheter and may allow the tip to deflect up to 70, 80, or 90 degrees in at least one direction. In an alternative, one or more of controls  51 ,  52 ,  53  (or other appropriate controls) are used to control extension of a balloon and/or hinged shell to provide stabilization at the distal end of the shaft  20 . 
         [0070]    The articulation provided by the access device  10  can work in combination with articulation provided by the instruments. For example, the access device  10  can be maneuvered to navigate to the general area of the treatment. Next, the articulation controls on the access device  10  can be used to position the head portion  40  of the access device  10  closer to the area of the treatment. Once in the desired general area, the articulation controls on the access device  10  can be fixed. Then, the articulation controls on the instrument can be used to precisely treat a particular region within the general area of treatment. There interplay between the gross and fine articulation facilitates quick and accurate device positioning and treatment. The access device  10  can also be configured to allow instruments to extend far beyond the tip of the access device  10 . This may be useful, for example, if the user needs to treat an area in the extremes of the pericardial space where access device  10  cannot itself go, e.g., wrapping around to the bottom or posterior side of heart. In such a circumstance, the user is able to push an ablation catheter or other instrument out further to get to those further positions. 
         [0071]    The articulation of the access device  10  can be controlled using various device configurations. In one embodiment, one or more pull wires that extend down the shaft  20  of the access device  10  are used. An alternative embodiment uses a coil or braided wire configuration that is part of the assembly of the shaft  20 . 
         [0072]      FIG. 18  depicts a distal tip portion of one embodiment of the access device  10 . In this embodiment, the access device  10  includes lever arms  51  and  52  that connect to opposing sides of the distal tip  50  of the access device. The lever arms  51 ,  52  attach to the respective opposite sides of the distal top  50  via pull wires (not shown) and are used to deflect the distal tip  50  in left direction or a right direction in a single plane. One or more such lever arm/pull wire configurations can be used to implement one or more articulation directions of the distal tip  50 .  FIG. 18  illustrates deflections of the distal tip  50  of 70° min in two directions in a single plane. 
         [0073]      FIGS. 19A and 19B  depict a distal tip portion  60  of a head  40  of one embodiment of the access device  10 . The distal tip portion  60  is tapered and has an instrument opening  21  for an instrument to perform a treatment. The camera  41  is positioned within the head  40  and provides a forward-facing view of the instrument opening  21 . 
         [0074]    Similarly,  FIGS. 20A and 20B  depict the distal tip portion  60  of the head  40  in another embodiment of the access device  10 . In this embodiment, the vacuum port  43  opens to the instrument channel  21  on the interior of the access device  10 , allowing a treatment instrument  61 , such as an ablation catheter, to treat tissue through the vacuum port  43 . 
         [0075]      FIGS. 21A and 21B  depict the distal tip portion  60  of the head  40  of additional embodiment of the access device  10 . In  FIG. 21A , the distal tip portion  60  has a tapered portion that defines additional opening  70  to provide camera visibility and/or provision of a fluid. In  FIG. 21B , the distal tip portion  60  has a relatively blunt portion  71  and the additional opening  70  is on a front surface of the distal tip  60  adjacent the instrument channel  21  rather than being on the relatively blunt portion  71 . 
         [0076]      FIGS. 22-25  illustrate the access device  10  according to another embodiment in which the head  40  includes a hinged shell  81 . The hinged shell attaches to the head  40  at hinges  82 , which enable the hinged shell  81  to extend away from the head  40 . In the example of  FIGS. 22-25 , the hinge shell  81  is attached to the top surface of the head  40  and configured to extend upward adjacent to the top surface of the head  40  without extending adjacent to the bottom surface of the head  40 . The hinged shell  81  also includes a guidewire opening  84  through which guidewire  90  ( FIG. 24 ) extends during the initial insertion of the access device  10 . In other words, the guidewire  90  is first inserted into the treatment area and then the access device  10  is inserted around the guidewire  90  with the guidewire  90  extending through a guidewire channel in the access device  10  and through the guidewire opening  84 . In this way, the guidewire opening  84  secures the hinged shell  81  in place during insertion and/or forward movement of the access device  10 . Alternative embodiments do not include or use a guidewire opening  84  in the hinged shell  81 . 
         [0077]    In embodiments of the invention, the upper surface of the hinged shell  81  has a smooth, hard surface. In embodiments of the invention, the upper surface is curved to reduce friction during insertion, movement, and articulation of the access device head  40 . In one embodiment, the hinged shell  81  is a canopy that at least partially surrounds the head  40  of the access device  10  when the hinged shell  81  is in a closed position. The hinged shell  81  can have a fingernail shape. The hinged shell  81  can have a shape that gradually narrows towards the tip  87 . The tip  87  of the hinged shell  81  can extend distally beyond the distal end  88  of the head  40 . The distal extension of the tip  87  beyond the distal end  88  can improve the amount of space created when the hinged shell  81  is extended upward away from the head  40 . For example, it can provide space for an ablation catheter  100  to ablate tissue and/or provide space for an injection needle to inject a substance. The tip  87  of the hinged shell  81  can be anti-reflective, opaque, or flat black to improve lighting and visualization conditions during use of the access device. 
         [0078]    In the example of  FIGS. 22-26 , the hinged shell  81  further includes a camera  83  on the access device  10 . The camera  83  is attached on an underside of the hinged shell  81  (for example under the tip  87  of the hinged shell) and oriented generally in a downward orientation to capture images of the treatment region and/or instruments used to perform treatment. The orientation of the camera can be selected based on an appropriate angle when the hinged shell  81  is in an extended position/a closed position, or both. For example, the camera  83  can be mounted in the hinged shell  81  at a 40 degree. In one example, the downward or closed position of the hinged shell  81  places the camera at a 70 degree angle relative to the hinged shell  81  hinge point. With the hinged shell  81  in the up or open position, the camera is projected out at 30 degree angle relative to the hinged shell  81  hinge point. This provides an optimal field of view when the hinged shell  81  is in an extended position. In one embodiment, fiber optic cable provides lighting that extends axially from the access device  10  while the camera provides an angled view from the hinged shell  81  of the region of the human body. This exemplary camera orientation can facilitate improved spatial reconciliation, allowing the user to see the treatment instrument and a topographical view of where the treatment instrument can be used to provide treatment with a region, for example, in relation to anatomical structures that should be treated or avoided. 
         [0079]    The camera  83  can involve a CMOS chip with optical fiber illumination permanently mounted in place. For example, illumination fibers can be equally spaced axially about the camera body. In one embodiment, illumination is provided through one or more fiber optic cables that provide light for the camera  83  from an external source without generating heat at the head  40  of the access device  10 . For example, light generation can occur proximally (e.g., in a box on a nearby table). 
         [0080]    The head  40  also includes openings  85 ,  86 ,  89  configured at the end of channels that provide passages for treatment instruments, diagnostic probes, light-providing fiber-optic cables, other instruments, pull wires and other articulation mechanisms for articulating the head and/or moving the hinged shell  81 , and/or fluids for inflating a balloon. In one example, instrument opening  86  is configured to allow an ablation catheter  100  ( FIG. 25 ) to extend to treat tissue in a treatment region of the patient and openings  89  are configured to provide a light from light channels (e.g., with fiber optic cables).  FIG. 23  shows an ultrasound transducer  93  mounted on the head  40 . The ultrasound transducer  93  is commutatively coupled, e.g., via a wire running through shaft  20  (e.g., through a channel through the shaft  20 ), to ultrasound processing equipment and/or displays. The position of the ultrasound transducer  93  on the head  40  can vary depending upon the intended use of the access device  10 . As examples, the ultrasound transducer  93  can be positioned adjacent to one or more of the openings  85 ,  86 ,  89 . If positioned adjacent an instrument opening  86 , the ultrasound transducer can specifically target the tissue about to be treated, being treated, or having been treated by a treatment instrument that extends from the instrument opening  86 . 
         [0081]      FIG. 25  illustrates the hinged shell  81  in an extended or raised position, i.e., where the distal end of the hinged shell  81  has been extended from the access device head  40 . Various features can be used to raise and lower the hinged shell  81 . In one example, one or more pull wires connect the hinged shell  81  to hinged shell controls. The hinged shell controls are configured to pull, hold, release, and extend the pull wire to extend and close the distal end of the hinged shell  81  away from the head  40 . A hinged plate affixed to the top of the distal end of the head  40  can be actuated by a pull wire. In an alternative embodiment, the hinged shell  81  is raised or lowered by a balloon  91  being inflated and deflated, respectively beneath the hinged shell  81 . The inflation/deflation of the balloon  91  can be controlled, for example, using a syringe. The hinged shell controls can be located on the handle  30 . In one embodiment, a hinged shell control is a thumb toggle on the handle  30 . 
         [0082]    The hinged shell  81  is generally configured to provide one or more functions provided by the balloon  42  described with reference to other embodiments of the access device  10 , as well as additional functions. Attributes of exemplary hinged shells can provide various advantages over certain balloon-based access devices  10 . For example, the relative hardness of the hinged shell  81  can provide greater stability than a relatively softer balloon. As another example, the hinged shell  81  can be controlled using pull-wire controls or other controls based on mechanical movements rather than injection and withdrawal of a fluid. Such mechanical-based controls may be easier, faster, and/or more convenient for some users. In addition, the fabrication and assembly of a device that uses a hinged shell  81  may be easier to fabricate, assemble, and/or prepare for use than an access device  10  that includes a balloon. 
         [0083]      FIG. 27  is a perspective view of an alternative embodiment of the access device configured to have a low profile. In this example the diameter of the access device can be 14 French or smaller. The relatively smaller diameter is achieved in this example using various design elements. For example, positioning and sizing the openings  89 ,  94  to the sides of the instrument opening  86  and having the corresponding channels in the similarly positioned can facilitate a slimmer profile. In one example, openings  89  are configured to provide a light from light channels (e.g., with fiber optic cables) and openings  94  are configured at the end of lumens through which pull wires or other articulation mechanisms run to enable control of articulation of the head  40  (e.g., allowing left or right articulation movement). In addition, the tip portion  88  of the head  40  is angled down from the longitudinal access. The opening along the bottom of the tip portion  88  reduces the size of the device (e.g., limiting the distance from the top of the shaft to the bottom of the tip portion  88  to 16 French or smaller). Accordingly, this embodiment accommodates a distal tip  88  configured to angle an instrument downward towards the tissue to be treated while minimizing the profile of the access device. 
         [0084]    The access device  40  can include a channel and corresponding opening to provide saline or another fluid to flush away tissue that is blocking or impairing the view in front of camera  83 . In some embodiments of the invention, such as a flush channel is provided through both the shaft  20  and through the hinged shell  81 . For example, a flush channel can be provided via a tube that extends through a channel in the shaft of the access device  10  and into a continuation of the channel that runs through the hinged shell  81  to an opening proximate the camera  83 . In another example, a fluid channel in the shaft  20  and a fluid channel in the fluid connection mechanism, such as flexible connector, that maintains the connection between the fluid channels when the hinged shell  41  is raised and/or lowered. In one example, the flush channel extends distally beyond the camera  83  within the hinged shell  81  and is configured to direct fluid back proximally at the lens of the camera  83 . Such a configuration may involve a curve or bend in the channel to direct the fluid in an appropriate direction. 
         [0085]      FIG. 28  is a longitudinal sectional view of the distal tip portion of an access device having a projecting bump  92  to guide an instrument at a downward angle towards tissue. Such a bump or other projection  92  can, for example, be used to guide an injection instrument such as a needle at an angle (e.g., at a 30, 35, 40, 45, or 50 degree angle from the axis of the instrument channel in the shaft of the access device). The angle can be created by a combination of an angle in the tip of the shaft and a projection at the opening. The angle can be selected for the particular application of the access device. For example, a 45 degree angle may be selected as appropriate for certain injection applications. 
         [0086]    The access devices  10  described herein can be manufactured using various manufacturing techniques. The shaft  20  can comprise polymer and metal materials of various diameters to ensure flexibility and guidance. It can be fabricated using common multi-layer catheter manufacturing techniques where stainless steel wire braids of particular, unique designs that afford specific hoop strength and flexibility when applied to specific polymer extrusions of particular and uniquely specified diameters, wall thicknesses and durometer to form a unique catheter assembly. 
         [0087]    The shaft  20  is preferably designed to articulate approximately 0 to 160 degrees inclusive in a lateral plane, including 45 to 120 degrees, and 0 to 100 degrees. The shaft  20  can have a length of 1 to 5 feet, including 30 cm to 60 cm. 
         [0088]    The head portion  40  can be fabricated using biocompatible polymer materials employing common injection mold processes and/or by additive manufacturing processes similar to stereolythogrophy. 
         [0089]    The handle portion  30  can be produced using various molded components of common biocompatible materials. 
         [0090]    A particular catheter design will have components for providing particular information to the user about the tissue being treated before, during, and after a therapeutic or diagnostic procedure is performed. This can involve a transducer that transmits and receives ultrasonic wave forms. An algorithm would be employed to determine the waveforms transmitted and received to develop the correct information to the user. 
         [0091]    Preferably, the access device  10  is comprised of materials that are able to withstand the temperature, moisture and pressure of typical sterilization processes such as ethylene oxide and Gamma radiation needed for fields like the thoracic cavity. Also, the shaft  20  and head portion  40  are preferably comprised of biocompatible materials that do not create extensive friction with the surrounding tissues. 
         [0092]    The access device  10  described herein enables a variety of new methods of providing treatment to patients. Exemplary methods of treatment include those that provide treatment within the pericardium under direct visualization. One such method involves inserting a guidewire  90  through a 2 centimeter (cm) or smaller sub-xiphoid incision in the skin of the human body or via percutaneous needle and guide wire access and into the pericardial space. The method next involves inserting a head  40  of the access device  10  into the pericardial space using the guidewire  90 , wherein the access device  10  comprises a shaft  20  comprising a proximal end and a distal end, the shaft  20  defining a lumen comprising channels extending longitudinally between the proximal end outside of the human body and the distal end attached to the head  40  in the pericardial space. The method further involves determining a region of the heart to treat based on a mapping of the heart. For example, this can involve determining which region to treat using an ultrasound transducer positioned at the head  40  and configured to determine tissue thickness and/or density. 
         [0093]    The method further involves positioning the head  40  of the access device  10  adjacent the portion of the heart to treat. For example, the user can push and pull the access device  10  using the handle  20  to push the head  40  of the access device  10  further into the pericardial space or pull the head  40  of the access device  10  back within the pericardial space. The user can additionally or alternatively articulate the access device to move the head  40  of the access device  10  left or right within the pericardium. In some embodiments, a camera  41 ,  83  of the access device  10  is activated to provide images to aid in the insertion and/or positioning of the access device  10 . 
         [0094]    The method then involves extending a portion (e.g., a balloon  42  or hinged shell  81 ) of the access device  10  away from a top surface of the access device  10  to separate the portion of the heart to treat from a surrounding portion of the pericardium. 
         [0095]    The method further involves viewing an image of the portion of the heart to treat adjacent the head of the access device. The image of the portion of the heart to treat captured by a camera  41 ,  83  at the head  40  of the access device  10 . For example, the camera can capture video images of the portion of the heart and/or images of an instrument inserted through the access device  10  to treat the portion of the heart. The images are used to confirm that the tissue that will be treated is the intended tissue and/or that arteries or other anatomical structures will not be inadvertently treated. 
         [0096]    The method further involves treating heart tissue in the portion of the heart to treat. In one example, treating the heart tissue involves using an electrophysiology (EP) ablation catheter inserted through one of the channels in the shaft  20  of the access device  10  to ablate the heart tissue. In another example, treating the heart tissue involves injecting a substance adjacent to or in the portion of the heart using an injection catheter inserted through one of the channels in the shaft  20  of the access device  10 . As a specific example, this can involve positioning the access device  10  at particular angle (e.g., approximately 45 degrees) relative to the surface of the tissue and injecting a substance adjacent to or in the portion of the heart using an injection catheter. The distal end of the instrument channel  21  can include an angle that causes an instrument passed through the instrument channel  21  to project at a downward angle relative to the axis of the shaft to better engage tissue. Treating the heart tissue can additionally or alternatively involve articulating a treatment catheter to precisely position a tip of the treatment catheter relative to the heart tissue. 
         [0097]    The method can involve treating one or more specific areas of the heart. To do so, the device is moved to a desired area, gross articulations are made using articulation controls on the access device, and fine articulations are made using articulation controls on a treatment instrument such as an ablation catheter or injection probe. After treating one area of the heart, the access device  10  is moved to treat one more additional areas of the heart. For each area, the user repositions the access device  10  and then performs gross and fine articulations as described above. Moreover, the balloon  42 , hinged shell  81 , or other component that is used to create space and/or stability can be retracted/closed to facilitate the movement from one area to the next. For example, a movement of the access device  10  can involve retracting the balloon  42  or hinged shell  81  to the top surface of the access device  10 , moving the access device  10  within the pericardial space, re-extending the balloon  42  or hinged shell  81  away from the top surface of the access device  10 , and/or performing the gross and fine articulations described above. 
         [0098]    The exemplary methods described above enable users to provide medical treatment with better success, efficiency, and ease than prior techniques. A user is able to view information on a screen during the procedure that allows the user to confirm that the treatment will only affect the desired portions of the anatomy. For example, such a screen may show the user a view from the camera, a mapping system such as the CARTO®3 System, or ENSITE NAVX or from an ultrasound transducer, information from sensors on an ablation or other treatment catheter, the patient&#39;s EKG, and other appropriate information. The user is then able to precisely position the access device  10  and treatment instrument to treat one or more specific areas. In many instances, the user will also be able to confirm that the treatment (e.g., ablation, injection, etc.) has been successful based on the visualization and other information provided on the screen. 
         [0099]    A number of aspects of the systems, devices and methods have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other aspects are within the scope of the following claims.