Patent Publication Number: US-2020276412-A1

Title: Catheter device for lumen re-entry and methods for use thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/556,610, filed on Sep. 11, 2017, and entitled “CATHETER DEVICE CATHETER DEVICE FOR LUMEN RE-ENTRY AND METHODS FOR USE THEREOF,” which is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Chronic total occlusions (CTO) can be found in coronary angiography, occurring in approximately 18-33% of patients with documented coronary artery disease. Percutaneous revascularization (angioplasty) is attempted in less than 10% of CTOs. Approximately 25% of cases undergo bypass surgery, while the majority (approximately 65%) are treated medically. The main reasons for not attempting percutaneous revascularization include the frequent presence of multi-vessel disease, and the complexity and time requirements of performing these technically challenging percutaneous procedures. 
     About 70% of percutaneous revascularization procedures are successful. This is primarily due to the difficulty in crossing the occlusion with guidewires in the antegrade direction. A challenge is crossing the fibrotic and often calcified material that is occluding the artery and then re-entering the true lumen beyond the occluded segment. In some cases, the guidewire immediately re-enters the true lumen at the end of the CTO (just past the distal end), which is known as true-true crossing. However, in many cases, the guidewire cannot cross the occlusion, but is in a subintimal position after the occlusion and has to re-enter the true lumen further downstream—so called true to false to true. In some cases, downstream re-entry can be done by reshaping the tip of CTO specialty guidewires advanced through a central lumen microcatheter (such as finecross or corsair) and directing the guidewire back into the true lumen. Also, angulated microcatheters can be used, but control of the angle of the tip can be challenging in the subintimal space. 
     More recently, a specialized CTO device has been introduced that first involves advancing a catheter (known as the CrossBoss), which is a proximal torque device that utilizes bidirectional rotation with a fast-spin technique, in order to advance across the occlusion as the spin reduces the push required. Although this catheter can be advanced within the luminal space, it is usually advanced within the subintimal space and then the CrossBoss catheter is replaced with a special flat balloon that has two holes at different orientations (Stingray balloon) through which the operator advances a very stiff guidewire (Stingray wire) to re-enter the artery. This is a technically challenging procedure that requires extensive training and has been restricted so far to highly expert operators. 
     Subintimal positioning of the guidewire (i.e. inside the wall of the coronary artery rather than the true lumen) after crossing the occlusion is a major problem and common failure more in CTO PCI, and highlights the need for additional options to facilitate re-entry into the true lumen of the artery after the occlusion. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure addresses the aforementioned challenges by providing a catheter device designed for lumen re-entry, which may be used for percutaneous CTO revascularization and other applications, such as angioplasty procedures where it can be challenging to position a guidewire in a side branch vessel with a difficult angulation. 
     It is an aspect of the present disclosure to provide a catheter that includes a catheter shaft having a tubular wall that extends from a proximal end to a distal end along a longitudinal axis to define a lumen. The tubular wall having formed therein an inner lumen that extends from the proximal end to the distal end of the catheter shaft. The catheter device also includes a deflection member coupled to the distal end of the catheter shaft and in fluid communication with the inner lumen such that fluid provided to the inner lumen causes the deflection member to expand from a first volume to a second volume that is larger than the first volume. When the deflection member is in the second volume, it extends from a surface of the tubular wall towards the longitudinal axis of the catheter shaft to provide a surface for deflecting an interventional device extending through the lumen and outward from the distal end of the catheter shaft at a deflection angle. 
     The foregoing and other aspects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a cross sectional view of an example of a distal portion of a catheter device having an expandable member; 
         FIG. 1B  is a cross sectional view of the example catheter device of  FIG. 1A  in which a wire is positioned therethrough; 
         FIGS. 2A-2D  show example configurations of deflection members that can be used with the catheter device described in the present disclosure. 
         FIG. 3  is an axial cross-sectional view of an example of a distal portion of the catheter device of  FIG. 1A  having an expandable member at a first volume; 
         FIG. 4  is an axial cross-sectional view of an example of a distal portion of the catheter device of  FIG. 1A  having an expandable member at a second volume; 
         FIG. 5  is a cross-sectional view of another example of a distal portion of a catheter device having an expandable member; 
         FIG. 6  is a cross sectional view of the example catheter device of  FIG. 3  in which a wire is positioned therethrough; 
         FIG. 7  is a perspective view of the example catheter device of  FIG. 3   
         FIG. 8  is a cross-sectional view of another example of a distal portion of a catheter device having an expandable member; 
         FIG. 9  is a perspective view of an example marked portion of any of the  FIGS. 1 to 8  positioned in which a “C” shape is visible; 
         FIG. 10  is an example of a medical image in which the “C” shape of  FIG. 9  is visible; 
         FIG. 11  is a perspective view of an example marked portion of any of the  FIGS. 1 to 8  positioned in which a “Z” shape is visible; 
         FIG. 12  is an example of a medical image in which the “Z” shape of  FIG. 11  is visible; 
         FIG. 13A  is a cross-sectional view of an example of a catheter device configured to interface with a catheter realignment system; 
         FIG. 13B  is a cross-sectional view of the example catheter device of  FIG. 16A  having a rod fed therethrough; 
         FIG. 14A  is a cross-sectional view of an example of a catheter device configured to interface with a catheter realignment system; 
         FIG. 14B  is a cross-sectional view of the example catheter device of  FIG. 17A  having a rod fed therethrough; 
         FIG. 15A  is a cross-sectional view of an example of a catheter device configured to interface with a catheter realignment system; 
         FIG. 15B  is a cross-sectional view of the example catheter device of  FIG. 18A  having a rod fed therethrough; 
         FIG. 16  is a perspective view of an example of a proximal end of a catheter realignment mechanism having a handle and a rod; 
         FIG. 17  is a perspective view of another example of a proximal end of a catheter realignment mechanism having a handle and a rod; 
         FIG. 18  is a perspective view of another example of a proximal end of a catheter realignment mechanism having a handle and a rod; 
         FIGS. 19A-19G  show the steps of an example subintimal re-entry procedure using an example of a catheter described in the present disclosure; and 
         FIGS. 20A-20G  show the steps of an example procedure for accessing a difficult side-branch using an example of a catheter described in the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     By way of overview and introduction, a catheter device that can provide subintimal orientation and re-entry into a lumen is generally illustrated in  FIGS. 1-18 . As will be described, one advantageous clinical use of the catheter device is treatment of chronic total occlusions (“CTO”). The catheter device can also be used for other vascular treatment applications, such as the placement of stents and angioplasty balloons, deflection of guidewires into angulated side branches from an intraluminal position, orientation of a guidewire at the beginning of occlusion to engage a CTO proximal to the CTO and at an angle that is not parallel to the artery, and non-vascular treatment applications. Generally, the catheter device can include an orientation subsystem and a re-entry subsystem. Embodiments of the re-entry subsystem will be described with respect to  FIGS. 1-8 . Embodiments of the orientation subsystem will be described with respect to  FIGS. 9-18 . 
     Referring now to  FIGS. 1A and 1B , the catheter  10  includes a catheter shaft  12  extending from a proximal end  14  to a distal end  16  along a longitudinal axis  18  to define a lumen  20 . A deflection member  22  is coupled to the shaft  12  at the distal end  16  of the catheter  10 . The deflection member  22  generally includes an expandable membrane that when filled with a fluid expands from a first volume (e.g., a deflated volume) to a second volume (e.g., an inflated or expanded volume). When expanded to the second volume, the deflection member  22  provides a surface for deflecting a guidewire, or other interventional device, extending through the lumen  20  outward through a distal opening  24  of the catheter shaft  12 . As will be described below, the expanded volume of the deflection member  22  provides a surface that will deflect the guidewire, or other interventional device, a deflection angle, θ, when exiting the opening  24  at the distal end  16  of the catheter  10 . 
     The wall of the catheter shaft  12  has formed therein an inner lumen  26  extending from the proximal end  14  to the distal end  16  of the catheter  10 . The inner lumen  26  receives a hypotube  28  that is in fluid communication with the deflection member  22 . The deflection member  22  generally spans an aperture  30  formed as the distal end of the inner lumen  26 , or any hypotube  28  provided to the inner lumen  26 . The aperture  30  can be formed in the distal end of the inner lumen  26 , as shown in  FIGS. 1A and 1B , or alternatively can be formed along the outer surface of the inner lumen  26  and through the catheter shaft  12  such that the deflection member  12  can be operated in a side-firing arrangement into the interior lumen  20  of the catheter shaft  12 . Providing a fluid to the hypotube  28  causes the deflection member  22  to expand from the first volume to the second volume. By controlling the amount of fluid provided to the deflection member  22  via the hypotube  28 , the second volume, and thereby the deflection angle, θ, provided by the deflection member  22 , can be similarly controlled. Thus, by controlling the expanded volume of the deflection member  22 , a guidewire, or other interventional device, can be deflected into the true lumen of a blood vessel when the catheter  10  is positioned in the subintimal space. 
     In some other embodiments, more than one deflection member  22  can be provided at the distal end  16  of the catheter  10 . In these configurations, a similar number of inner lumens  26  are formed in the wall of the catheter shaft  12  such that a different hypotube  28  may be provided to each inner lumen  26  to be in fluid communication with one of the deflection members  22 . 
     In some embodiments, the wall of the catheter shaft  12  does not include an inner lumen  26 ; rather, the hypotube  28  is provided to the interior surface of the lumen  20  of the catheter shaft  12 . In such configurations, it will be appreciated that more than one hypotube  28  can be similarly provided to the interior surface of the lumen  20  of the catheter shaft  12 . It will also be appreciated that in some embodiments a hypotube  28  can be provided to both an inner lumen  26  formed in the wall of the catheter shaft  12 , and to the interior surface of the lumen  20  of the catheter shaft  12  itself. 
     The wall of the catheter shaft  12  can be chamfered or beveled such that the wall slopes proximally toward the distal opening  24  of the catheter  10 , thereby defining an angled surface  32 . The angled surface  32 , in turn, defines a maximum deflection angle at which a guidewire, or other interventional device, can be deflected upon exiting the opening  24  at the distal end  16  of the catheter  10 . In some configurations, the exterior surface of the catheter shaft  12  may be inwardly tapered distal to a taper line  36  towards the distal end  16  of the catheter  10 . 
     As mentioned above, and as shown in  FIGS. 1A and 1B , the catheter  10  can receive a guidewire  34  that can be fed through the lumen  20  from the proximal end  14  to the distal end  16  of the catheter  10 . The guidewire  34  can be directed through the opening  24  at the distal end  16  of the catheter  10  via contact with the deflection member  22  and the angled surface  32  of the catheter shaft  12 . That is, the guidewire  34  is deflected by contact with the deflection member  22  so as to extend outward from the distal opening  24  at the deflection angle. 
     The deflection member  22  is generally constructed as an expandable membrane that spans the aperture  30  in the catheter shaft  12  formed by the inner lumen  26 . In some other configurations, the deflection member  22  can be constructed as an expandable membrane that spans the opening of the hypotube  28 . That is, the deflection member  22  can be coupled to the catheter shaft  12  or to the hypotube  28 . As described above, fluid is provided to the deflection member  22  via the hypotube  28  to expand the deflection member from a first volume to a second volume. The deflection member  22  can have a partially spherical shape; although, other shapes can also be implemented, such as partially ellipsoidal shapes and the like. The deflection member  22  can extend outwardly from the distal end  16  of the catheter  10  along a direction perpendicular, or nearly perpendicular, to the angled surface  32  of the catheter shaft  12 . 
     In some embodiments, the deflection member  22  can be constructed as an extruded sleeve that spans the aperture  30  in the catheter shaft  12  formed by the inner lumen  26 . Alternatively, the extruded sleeve can span a first aperture that is formed in the hypotube  28 , which is aligned with a suitable second aperture in the catheter shaft  12 , such as aperture  30 . An example of this configuration in an undeployed state is shown in  FIG. 2A  and in a deployed state in  FIG. 2B . In this example, the aperture  30  in the catheter shaft  12  formed by the inner lumen  26  terminates on the inner surface of the catheter shaft  12  such that the deflection member  22  will be deployed in a side-firing configuration. The deflection member  22  is also shown in this example as a balloon that is inflated when fluid is provided through the hypotube  28  to the interior volume of the deflection member  22  in its undeployed state. As noted, the deflection member  22  in this example can be constructed as an extruded sleeve  50 . The deflection member  22  can also be constructed by dipping the catheter shaft  12  or hypotube  28  in a suitable material to form the deflection member  22  in its undeployed state. The deflection member  22  can be composed of silicon, polyurethane, silicone polypropylene, PEBAX® (Arkema; Colombes, France), or other suitable expandable material, which may include a polymer, elastomer, or so on. 
     In some other embodiments, the deflection member  22  can be constructed as a patch  52  made by an extruded sleeve that spans the aperture  30  in the catheter shaft  12  formed by the inner lumen  26 . Alternatively, the patch  52  can span a first aperture that is formed in the hypotube  28 , which is aligned with a suitable second aperture in the catheter shaft  12 , such as aperture  30 . The patch  52  can also be formed by dipping the catheter shaft  12  or hypotube  28  in an expandable material that spans the aperture  30  in the catheter shaft, or an aperture formed in the hypotube  28 . An example of this configuration is shown in an undeployed state in  FIG. 2C  and in a deployed state in  FIG. 2D . In this example, the aperture  30  in the catheter shaft  12  formed by the inner lumen  26  terminates on the inner surface of the catheter shaft  12  such that the deflection member  22  will be deployed in a side-firing configuration. The patch  52  can span a portion of the circumference of the catheter shaft  12  or hypotube  28 , as shown in  FIG. 21C . The deflection member  22  is also shown in this example as a balloon that is inflated when fluid is provided through the hypotube  28  to the interior volume of the deflection member  22  in its undeployed state. As noted, the deflection member  22  in this example can be constructed as a patch  52  made by an extruded sleeve or by dipping the catheter shaft  12  or hypotube  28  in a suitable material to form the deflection member  22  in its undeployed state. The deflection member  22  can be composed of silicon, polyurethane, silicone polypropylene, PEBAX® (Arkema; Colombes, France), or other suitable expandable material, which may include a polymer, elastomer, or so on. 
     As described above, when a fluid is provided to the deflection member  22  via the hypotube  28 , the deflection member  22  expands from the first volume to a second volume. When the deflection member  22  has the second volume it partially extends into the opening  24  at the distal end  16  of the catheter  10 , thereby providing a surface that will deflect a guidewire, or other interventional device, passing through the opening  24  at the distal end  16  of the catheter  10 . As one non-limiting example, when the deflection member  22  has the first volume, the deflection member  22  has a substantially flat shape. That is, the deflection member  22  can be relatively flat against the angled surface  32  of the catheter shaft  12 . In some other embodiments, the deflection member  22  can be partially protruding from, or partially recessed relative to, the angled surface  32  of the catheter shaft  12 . As the pressure supplied to the deflection member  22  by the fluid is decreased, the deflection member  22  can begin to compress and transition from the expanded shape at the second volume to the flatter shape against the angled surface  32  at the first volume. It should be appreciated that the deflection member  22  can be partially expanded, thereby expanding the deflection member  22  into an intermediate position. 
     In some embodiments, the catheter  10  is constructed to be a microcatheter. As one example, the catheter  10  can be constructed as a microcatheter for use in coronary arteries. Thus, in some non-limiting examples, the catheter  10  can be sized at 4.5 Fr (1.5 mm) or less. As another example, the catheter  10  can be constructed to be a microcatheter for use in peripheral arteries, which can allow a larger outer diameter than in coronary microcatheter implementations. 
     Referring to  FIGS. 3 and 4 , a view looking down the catheter shaft  12  from the distal end  16  of the catheter  10  is shown with the deflection member  22  at the first volume ( FIG. 3 ) and at the second volume ( FIG. 4 ). As shown, the catheter shaft  12  can be a tubular structure that defines the lumen  20  within the tubular structure of the catheter shaft  12 . The catheter shaft  12  is generally composed of a medical device class VI approved polymer material, such as, for example, polyethylene terephthalate (“PET”); however, other polymer materials could also be employed, such as other related PET formulations, polyethylene naphthalate (“PEN”), polyether ether ketone (“PEEK”), and polyether block amide (“PEBA”), such as PEBAX® (Arkema; Colombes, France). 
     In some embodiments, the catheter can be composed of more than one material. As one example, the catheter shaft can have first layer composed of a first material and a second layer composed of a second material. In such embodiments, the first layer can correspond to the inner surface of the catheter shaft  12  and the second layer can correspond to the outer surface of the catheter shaft  12 . The first layer can be thin, such as 0.001″, and the second layer can be molded around the first layer and any hypotubes  28  positioned in the wall of the catheter shaft  12 . As one benefit, this two-layered composition can facilitate creating a varied outer diameter for the catheter shaft  12 , such as creating a tapered outer surface for the catheter shaft  12 , as described above. In these embodiments, the deflection member  22  can be molded into the first layer. In other embodiments, the deflection member  22  can be formed by applying a thin membrane (e.g., a thin membrane of latex plastic or other such material) across a hypotube  28 . 
     Referring to  FIGS. 5 and 6 , another example of a catheter  10  of the present disclosure is illustrated. In this example, the catheter  10  generally includes a catheter shaft  12  extending from a proximal end  14  to a distal end  16  along a longitudinal axis  18  to define a lumen  20 . In this example, the catheter  10  is generally constructed such that the catheter shaft  12  includes a single inner lumen  26 . As shown, the inner lumen  26  is generally positioned on a first side  38  of the catheter shaft  12 . In some configurations, the second side  40  of the catheter shaft  12  can have a thinner outer wall than the first side  38 . As mentioned above, in some embodiments the hypotube  28  may be provided to the interior surface of the lumen  20  of the catheter shaft  12  rather than an inner lumen  26  formed in the wall of the catheter shaft  12 . 
     The catheter shaft  12  can be constructed to have an extended portion  42  of the wall of the catheter shaft  12  that extends distally beyond the opening  24 . As shown, the extended portion  42  of the wall of the catheter shaft  12  extends more distal on the first side  38  of the catheter shaft. The portion of the wall of the catheter shaft  12  that does not include the extended portion  42  may be tapered to a thinner thickness than an opposing portion of the wall of the catheter shaft  12 . The extended portion  42  of the catheter shaft  12  can span one-half of a circumference of the catheter shaft  12 , or may span more or less than one-half of the circumference of the catheter shaft  12 . 
     In these embodiments, the inner lumen  26  terminates in the extended portion  42  of the catheter shaft  12  without opening to the distal end  16  of the catheter shaft  12 . However, an aperture  30  is formed on the inner surface of the catheter shaft  12 , such that the inner lumen  26  is open to the inner surface of the catheter shaft  12  by way of the aperture  30 . The deflection member  22  in this configuration can be coupled to the inner surface of the catheter shaft  12  and can be made to span the aperture  30  such that the deflection member  22  is in fluid communication with a hypotube  28  provided to the inner lumen  26 . The deflection member  22  can have a generally hemi-spherical shape that provides a deflection member  22  that is “side-firing” in the sense that the deflection member  22  expands into the lumen  20  of the catheter shaft  12  towards the longitudinal axis  18  of the catheter  10  when expanding from the first volume to the second volume. 
     The deflection member  22  is coupled to the aperture  30 , such that the aperture  30  provides fluid communication between the deflection member and the hypotube  28  positioned in the inner lumen  26  to provide a fluid to the deflection member  22 . The fluid provided to the deflection member  22  can facilitate expansion of the deflection member  22  to the second volume as described above. The deflection member  22  at the second volume partially extends into the distal opening  24  of the catheter  10  to provide a surface that will deflect a guidewire or other interventional device extending through the lumen  20  of the catheter shaft  12  by a projection angle, θ. At the first volume, the deflection member  22  can have a substantially flat shape. As fluid is removed from the deflection member  22  its volume will decrease again from the second volume to the first volume. It should be appreciated that the deflection member  22  can be partially expanded, thereby expanding the deflection member  22  to an intermediate volume. 
     One example of the embodiment of the catheter  10  as described above can be sized at 4.5 Fr (1.5 mm). In such embodiments, the catheter  10  can be a referred to as a microcatheter. In some implementations, the catheter  10  may be sized for use in coronary arteries, and in some other implementations the catheter  10  may be sized for use in peripheral arteries. 
     In another embodiment, the catheter shaft  12  can be constructed to be angled at its distal end  16 , as shown in  FIG. 7 , such that the catheter shaft  12  extends distally farther on one side  41  than on the other side  43  forming a sloped outer surface to the distal end  16  of the catheter shaft  12 . In these instances, the inner lumen  26  may terminate within the wall of the catheter shaft  12 . Like the embodiments described with respect to  FIGS. 5 and 6 , an inward facing aperture  30  is formed in the wall of the catheter shaft  12  to provide fluid communication between the inner lumen  26  and a deflection member  22  coupled to the aperture  30 . As described above, a hypotube  28  can be provided in the inner lumen  26 , or the lumen  20  of the catheter shaft  12 , to facilitate providing a fluid to the deflection member  22  to adjust the volume of the deflection member  22  between the first volume and the second volume. In the configuration shown in  FIG. 7 , the deflection member  22  is arranged opposite the lower side  43  of the catheter shaft  12  at its distal end  16 . 
     In another embodiment of the catheter  10 , a positioning member  44  can be coupled to the catheter shaft  12  at the distal end  16  of the catheter  10 , as shown in  FIG. 8 . The positioning member  44  can be coupled adjacent a deflection member  22 , such that expanding the deflection member  22  from a first volume to a second volume will deflect or otherwise articulate the positioning member  44  from a first position to a second position. As an example, in the second position the positioning member  44  can provide a surface for deflecting a guidewire or other interventional device by a deflection angle. 
     As one example of the embodiments described above, the catheter  10  can be sized at 4.5 Fr (1.5 mm). In some implementations, the catheter  10  may be sized for use in coronary arteries, and in some other implementations the catheter  10  may be sized for use in peripheral arteries. 
     In operation, the catheter  10  should be properly oriented within the subintimal space, so as to ensure that the guidewire, or other interventional device, extending through the lumen  20  of the catheter  10  will be deflected back into the true lumen of the blood vessel. To this end, the catheter  10  can be constructed to include a radiopaque orientation marker that uniquely indicates the orientation of the catheter shaft  12  within the subintimal space. The catheter  10  can also include a realignment assembly that can be used to reorient the catheter  10  while it resides in the subintimal space, such that the deflection of the guidewire, or other interventional device, will be made into the true lumen of the blood vessel. 
     Referring now to  FIGS. 9 and 10 , one example of a radiopaque orientation marker  60  that is disposed on the catheter shaft  12  of the catheter  10  is shown. The radiopaque orientation marker  60  can be positioned on the catheter shaft  12  proximal to a taper line  36 , such as those described above. The radiopaque orientation marker  60  is composed of a radiopaque material and generally has an asymmetrical shape around the outer surface of the catheter shaft  12 . The asymmetrical shape provides an indication of the orientation of the catheter  10  based on the shape displayed to a user. The catheter  10  can be rotated as will be discussed below, and the rotation of the catheter  10  changes a view of the radiopaque marker  60 . As shown in  FIGS. 9 and 10 , the radiopaque orientation marker  60  may be shaped such that when oriented in a first orientation and viewed along a particular line-of-sight the radiopaque orientation marker  60  will be displayed as a “C-shaped” object in an x-ray image. When the radiopaque orientation marker  60  is rotated to a second orientation and viewed along the same line-of-sight, the radiopaque orientation marker  60  will be displayed as a “Z-shaped” object in an x-ray image. Thus, based on the unique shape of the radiopaque orientation marker  60 , a user can visualize the current orientation of the catheter in an x-ray image. It will be appreciated that the radiopaque orientation marker  60  could also be composed of a material that renders it visible in images acquired with other medical imaging modalities, such as magnetic resonance imaging. 
     To adjust the orientation of the catheter  10 , a realignment assembly can be implemented. As shown in  FIGS. 13A and 13B , the realignment assembly  62  can generally include a rod  64  that is provided to the catheter shaft  12  of the catheter  10 . The rod  64  interfaces with a receiving portion  66  in the catheter shaft  12 , at which the rod  64  becomes coupled to the catheter shaft  12 . When interfaced with the receiving portion  66  of the catheter shaft  12 , rotation of the rod  64  will result in a rotation of the catheter shaft  12 , at least at the distal end  16  of the catheter  10 , thereby providing a realignment, or reorientation, of the catheter shaft  12 . 
     In the embodiment shown in  FIGS. 13A and 13B , the receiving portion  66  includes protrusions  68  disposed on the interior wall of the catheter shaft  12 . These protrusions  68  create a decreased diameter of the lumen  20  of the catheter shaft  12 . The protrusions  68  may be curved or otherwise shaped to provide a reduced diameter of the lumen  20  of the catheter shaft  12 . The protrusions  68  can be semi-deformable. When the rod  64  is provided to the receiving portion  66 , the protrusions  68  will contact the distal end of the rod  64 , thereby creating an interference fit between the rod  64  and the receiving portion  66 . In this arrangement, the rod  64  becomes mechanically coupled to the catheter shaft  12  such that when the rod  64  is rotated it provides a rotation of the catheter shaft  12 . 
     In one embodiment, shown in  FIGS. 14A and 14B , the realignment assembly  62  can include a rod  64  that is tapered at its distal end. The receiving portion  66  of the catheter shaft  12  is similarly tapered to receive the tapered rod  64 . The tapering of the receiving portion  66  provides a tapered fit with the rod  64  such that the rod  64  becomes mechanically coupled to the catheter shaft  12  when interfaced with the receiving portion  66 . As such, when the rod  64  is rotated it provides a rotation of the catheter shaft  12 . 
     In another embodiment shown in  FIGS. 15A and 15B , the realignment assembly  62  can include a rod  64  that is shaped at its distal end to mate with the receiving portion  66  of the catheter shaft  12 . For example, the rod  64  and receiving portion  66  can collectively define a “lock and key” mechanism. The receiving portion  66  can include an annular stopper  70  coupled to the inner wall of the catheter shaft  12  and having one or more notched recesses  72  that receive similarly shaped protrusions  74  extending distally from the distal end of the rod  64 . In some configurations, such as the one shown in  FIGS. 15A and 15B , the notched recesses can be mirrored curved recesses that are recessed from the proximal surface of the stopper  70  opposite each other. The keyed end of the rod  64  can have a cylindrical central member  76  and opposing curved protrusions  74  that are shaped to interface with the recesses  72  and the annular stopper  70 . When the keyed end of the rod  64  is interfaced with the recesses  72  in the annular stopper  70 , the rod  64  becomes mechanically coupled to the catheter shaft  12  such that when the rod  64  is rotated it provides a rotation of the catheter shaft  12 . 
     Referring to  FIG. 16 , at its proximal end the rod  64  can have a handle  78  that is cylindrical in shape with a tapered distal end that tapers radially inward to meet the rod  64 . The outer surface of the handle  78  can feature a plurality of ribs  80  having a raised profile and extending along a length of the outer surface of the handle  78 . The rod  64  can be generally cylindrical in shape and can extend to any appropriate length to its distal end. Referring to  FIG. 17 , as another example, the handle  78  of the rod  64  can be generally cone-shaped being tapered radially inward to meet the rod  64  at a distal end of the handle  78 . Referring to  FIG. 18 , as another example, handle  78  of the rod  64  can have a proximal body  82  that is generally spherical in shape and a distal body  84  that is generally cylindrical in shape and interfaces with the rod  64 . 
     Having generally described the features of the various embodiments of the catheter  10 , a discussion of its general mode of operation is provided. By way of example, the operation of the various embodiments of the catheter  10  will be described with respect to treatment of chronic total occlusions in a patient. The catheter  10  can be configured as a re-entry component for re-entering a true lumen of a patient once the catheter  10  has been oriented at a desired orientation in the subintimal space. In percutaneous revascularization therapy, it is desirable to have the catheter  10  positioned after the chronic total occlusion(s) prior to re-entry in order to facilitate the procedure. As noted above, it should be appreciated by those skilled in the art that the catheter  10  can be employed for other procedures. 
     The catheter  10  can be positioned in the subintimal space of a patient near an occlusion designated for treatment. The deflection member  22  receives fluid from a hypotube  28  disposed within the inner lumen  26  or provided to the interior surface of the lumen  20  of the catheter shaft  12 , and the fluid causes the deflection member  22  to expand from the first volume to the second volume. The fluid supplied to the deflection member  22  can be controlled by a user at a proximal end  14  of the catheter  10 . As one example, the fluid can be supplied via a syringe, similar to those used in balloon catheters. 
     When the deflection member  22  is expanded to the second volume, it partially extends into the distal opening  24  of the catheter  10  to provide a surface that will deflect a guidewire or other interventional instrument by a projection angle, θ. It will be appreciated that during a percutaneous revascularization procedure multiple different guidewires can be interchangeably used with the catheter  10 . For instance, the guidewire can be changed for a stiffer or slippery guidewire to penetrate through the subintimal tissue to facilitate reentry into the vessel lumen. The deflection surface can be positioned on an interior side of the deflection member  22  such that when the guidewire  34  extends through the distal opening  24  of the lumen  20  of the catheter  10 , the guidewire  34  will make contact with and be deflected by the surface of the deflection member. Contact between the surface of the deflection member  22  and the guidewire  34  deflects the guidewire  34  through the distal opening  24  along the projection angle, θ. The guidewire  34  may also contact the angled surface  32  that provides proximal support to the guidewire  34  when deflected through the distal opening  24 . The guidewire  34  can extend distally from the distal end  16  of the catheter device along the projection angle, θ. The projection angle, θ, can be determined by a user pre-operatively or during operation in order to facilitate re-entry into the true lumen beyond the occlusion and can be selectively controlled by adjusting the volume of the deflection member  22  as needed. The catheter  10  can then be advanced over the guidewire  34  into the true lumen beyond the occlusion. 
     During revascularization therapy using the catheter devices described in the present disclosure, it is generally desirable for the user to understand an orientation of the catheter device in order to determine the proper projection angle and to ensure the catheter device is oriented properly such that the projection angle is positioned for re-entry into the true lumen. Accordingly, the radiopaque orientation marker  60  described above and shown in  FIGS. 9-12  can be used to assist in alignment of the catheter  10 . The asymmetrical shape of the radiopaque orientation marker  60  provides an indication of the orientation of the catheter  10  based on the appearance of the shape of the radiopaque orientation marker  60  displayed in an x-ray or other medical image of the catheter  10 . 
     Rotation of the catheter  10  to a desired orientation can be achieved using the realignment assembly described above. By causing rotation of the rod  64  while it is interfaced with the receiving portion  66  of the catheter shaft, the catheter  10  can be rotated between different orientations. The rod  64  can be stiff and allow for increased translation of rotation applied by a user at the handle  78  located at the proximal end of the rod  64 . The rod  64  can also provide support along the length of the catheter shaft  12  to rotate the catheter shaft  12  without kinking. Once the desired orientation is achieved, the rod  64  can be removed from the lumen  20  of the catheter shaft  12  and then be replaced with a guidewire for re-entry into the true lumen as discussed above. 
     Thus, as one non-limiting example of its use, the catheter  10  will be oriented in the proper direction beyond the occlusion using the radiopaque orientation marker  60  and the orientation rod  64 . A guidewire will be advanced to the tip of the catheter  10 , beside the uninflated deflection member  22 . The deflection member  22  will then be expanded, angling the guidewire into the vessel lumen. The guidewire will then be advanced into the true lumen beyond the occlusion. The catheter  10  will then be advanced over the guidewire and into the true lumen to secure the position. After the guidewire has been advanced into the distal lumen, the catheter  10  in the subintimal space may be exchanged for a balloon catheter or different microcatheter while maintaining the wire position in the distal lumen. 
     As described, the catheter  10  can be used in CTO interventions, specifically directing a guidewire from the subintimal space towards the true lumen. The catheter  10  can also be used for directing a guidewire down a difficult to access side branch (in narrowed but not occluded arteries), for example. 
     Referring now to  FIGS. 19A-19G , an example method for using the catheter  10  described in the present disclosure for a subintimal re-entry procedure is shown. A section of an artery with a chronic total occlusion is shown in  FIG. 19A . A surgeon positions a guidewire to enter the subintimal space proximal to the occlusive plaque, as shown in  FIG. 19B . The microcatheter is then tracked over the guidewire into the subintimal space, as shown in  FIG. 19C . The microcatheter is in the correct orientation for re-entry to the true lumen, as indicated by the “C” shaped marker facing towards the true lumen. If, however, the microcatheter is tracked over the guidewire into the subintimal space and catheter is not in the correct orientation for re-entry to the true lumen, as shown in  FIG. 19D  and indicated by the backwards “Z” shaped marker facing towards the true lumen, the orientation rod is inserted into the microcatheter to re-orient the microcatheter until the “C” shaped marker faces towards the true lumen. The guidewire is then pulled back inside the microcatheter until just the distal tip of the guidewire protrudes out of the opening, as shown in  FIG. 19E . The expandable membrane of the deflection member is then inflated to angulate the distal tip of the guidewire, which can then be advanced to re-enter the true lumen, as shown in  FIG. 19F . The catheter is then advanced over the guidewire into the true lumen, as shown in  FIG. 19G . Alternatively, the guidewire is advanced into the distal lumen, and the microcatheter is withdrawn and can be replaced with a different catheter 
     Referring now to  FIGS. 20A-20G , an example method for using the catheter  10  described in the present disclosure for accessing a difficult to reach side branch is shown. In this example, the difficult to reach side branch is in an atherosclerotic right coronary artery, as shown in  FIG. 20A . A surgeon positions a guidewire to enter the right coronary artery, but cannot access the side branch, as shown in  FIG. 20B . The microcatheter is tracked over the guidewire, as shown in  FIG. 20C . In this example, the microcatheter is in the correct orientation for angulating the guidewire into the side branch, as indicated by the “C” shaped marker facing towards the side branch. If, however, the microcatheter is tracked over the guidewire and is not in the correct orientation for angulating the guidewire into the side branch, as shown in  FIG. 20D  and indicated by the backwards “Z” shaped marker facing towards the side branch, then the orientation rod is inserted into the microcatheter to re-orient the microcatheter until the “C” shaped marker faces towards the side branch. The guidewire is then pulled back inside the microcatheter until just the distal tip of the guidewire protrudes out of the opening, as shown in  FIG. 20E . The expandable membrane of the deflection member is inflated to angulate the distal tip of the guidewire, which can then be advanced to enter the side branch, as shown in  FIG. 20F . When the guidewire successfully accessed the side branch, the microcatheter can either be advanced over the guidewire, or replaced with a different catheter, as shown in  FIG. 20G . 
     One advantage of the catheter  10  described in the present disclosure is that the configuration can be constructed to maintain the outer dimensions of a microcatheter, and will have a lower risk of causing harm to the artery or the subintimal space when used in the coronary arteries. That is, the deflection member  22  and other components of the catheter  10  described in the present disclosure are located within the catheter shaft  12 , and the dimensions of these components can thus be sized so as not to exceed the microcatheter outer diameter. The ability of the catheter  10  to direct the guidewire out of the distal tip also allows for the catheter  10  to be advanced across a lesion without requiring the catheter  10  to be replaced. 
     The catheter  10  described in the present disclosure can enable cardiologists to successfully perform percutaneous coronary interventions for complex chronic total occlusions. The catheter  10  can allow for an alternative method for directing a guidewire from the subintimal space into the true lumen that can reduce procedural costs and have a lower risk of complications as compared to current devices. Another advantage is that because the catheter  10  stays in place throughout the subintimal entry, little to no blood will track through the subintimal plane of tissue, which can otherwise occur when the a device (e.g., the CrossBoss described above) is removed and replaced with another device (e.g., the Stingray described above). As a result, the subintimal space will be prevented from filling up with blood and compressing the true lumen. In turn, the subintimal entry is made easier because the true lumen beyond the CTO is maintained. If the true lumen is compressed by blood tracking in the subintimal space, the distal lumen may become very difficult to visualize. 
     The present invention has been described in terms of one or more preferred embodiments, and it should be appreciated that many equivalents, alternatives, variations, and modifications, aside from those expressly stated, are possible and within the scope of the invention.