Patent Publication Number: US-2022226611-A1

Title: Steerable catheters

Description:
INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/724,826, filed Dec. 23, 2019, which is a continuation of U.S. patent application Ser. No. 15/497,542, filed Apr. 26, 2017, which is a divisional of U.S. patent application Ser. No. 13/801,888, filed Mar. 13, 2013 and issued as U.S. Pat. No. 9,636,480 on May 2, 2017, each of which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The present application relates generally to steerable catheters. 
     BACKGROUND 
     Catheters are routinely used in medical procedures and serve various functions, including drainage, administration of fluids or gases, allowing surgical instruments access to treatment sites, etc. A catheter can be inserted into a body lumen through the skin or percutaneously. The catheter is then guided to an area of interest by advancing the catheter through the lumen. As medical technology advances, catheters are being used for more and more complicated procedures. Accurate navigation of the catheter to a particular luminal position can be useful for successful treatment. 
     SUMMARY 
     In some embodiments, a steerable catheter comprises a handle at a proximal portion of the steerable catheter, the handle including a proximal end, a distal end, and an axis between the proximal end of the handle and the distal end of the handle. The handle comprises a plurality of resilient metal strips coupled at the proximal end of the handle and at the distal end of the handle, the metal strips biased into an arcuate configuration, the metal strips extending away from the axis from the proximal end of the handle to an intermediate point along the handle and the metal strips extending towards the axis from the intermediate point to the distal end of the handle. The handle comprises a cover over the plurality of resilient metal strips. The catheter also comprises an elongate tubular body, the tubular body including a proximal portion and a distal portion. The proximal portion is coupled to the distal end of the handle. The distal portion includes a distal end of the tubular body. A plurality of lumens extends from the proximal portion to the distal portion. The distal portion comprises a shape-memory ribbon longitudinally extending along the tubular body proximate to the distal end of the tubular body. The steerable catheter comprises a pull wire extending from the proximal end of the handle to the distal end of the tubular body through one lumen of the plurality of lumens, a second lumen of the plurality of lumens configured to provide a path for an endoluminal device. Upon manual inward compression of at least some of the resilient metal strips, the at least some of the resilient metal strips compress from the arcuate configuration to a straighter configuration, a degree of straightening corresponding to a force applied during the manual inward compression of the at least some of the resilient metal strips. The proximal end of the handle and the pull wire extend proximally, a degree of proximal extension corresponding to the force applied during the manual inward compression of the at least some of the resilient metal strips. The distal portion of tubular body deflects from a substantially straight configuration to a curved configuration, a degree of deflection corresponding to the force applied during the manual inward compression of the at least some of the resilient metal strips. Upon manual decompression of the at least some of the resilient metal strips, the at least some of the resilient metal strips rebound towards the arcuate configuration, a degree of rebounding corresponding to a force of the manual decompression of the at least some of the resilient metal strips. The proximal end of the handle and the pull wire extend distally, a degree of distal extension corresponding to the force of the manual decompression of the at least some of the resilient metal strips. The shape-memory ribbon deflects the distal portion of the tubular body from the curved configuration to the substantially straight configuration, a degree of uncurling corresponding to the force of the manual decompression of the at least some of the resilient metal strips. Upon rotation of the handle about the axis, the distal end of the tubular body rotates. The handle is rotatable at least 360° about the axis by rolling between a thumb and fingers of a user. 
     In some embodiments, a steerable catheter comprises a handle including a proximal end, a distal end, and an axis between the proximal end of the handle and the distal end of the handle. The handle comprises comprising a plurality of resilient and flexible struts coupled at the proximal end of the handle and at the distal end of the handle. The struts are biased into an elliptical configuration, extending away from the axis from the proximal end of the handle to an intermediate point along the handle and the struts extending towards the axis from the intermediate point to the distal end of the handle. The steerable catheter also comprises an elongate tubular body including a proximal portion and a distal portion. The proximal portion is coupled to the distal end of the handle. The distal portion includes a distal end of the tubular body. A lumen extends from the proximal portion to the distal portion. The distal portion comprises a resilient component. The catheter comprises a pull wire extending from the proximal end of the handle to the distal end of the tubular body through the lumen. The pull wire is configured to extend proximally upon inward compression of the handle proportional to a force of the inward compression. The distal portion is configured to curve upon inward compression of the handle proportional to the force of the inward compression. The handle is rotatable at least 360° about the axis by rolling between a thumb and fingers of a user. 
     The struts can comprise a wire or ribbon. In some embodiments the struts comprise nitinol. The handle can comprise a cover over the plurality of struts. In some embodiments, the resilient component comprises a longitudinally extending ribbon. The resilient component can comprise a shape memory material. In some embodiments, the catheter comprises a second lumen configured to provide a path for an endoluminal device. Upon manual decompression, the pull wire can be configured to retract distally proportional to a force of the decompression and the distal portion of the tubular body can be configured to straighten upon decompression of the handle proportional to the force of the decompression. The catheter can comprise a second pull wire extending from the proximal end of the handle to the distal end of the tubular body. The second pull wire can be configured to extend proximally upon inward compression of a second part of the handle proportional to a force of the inward compression and the distal portion of the tubular body can be configured to curve in a second direction different than the first direction upon inward compression of the second part of handle proportional to the force of the inward compression. The first and second pull wire can be coupled to the distal end of the tubular body at pull wire fix points, the pull wire fix points spaced circumferentially around a circumference of the tubular body proximate to the distal end of the tubular body. The catheter can comprise a locking mechanism configured to maintain the pull wire in an extended configuration. 
     In some embodiments, a method of using a steerable catheter comprises advancing a handle, the handle coupled to an elongate tubular body in a lumen, the handle comprising a proximal end, a distal end, and an axis between the proximal end of the handle and the distal end of the handle. The handle comprises a plurality of resilient and flexible struts biased into an arcuate configuration, the struts coupled at the proximal end of the handle and the distal end of the handle, the struts extending away from the axis from the proximal end of the handle to an intermediate point along the handle and the struts extending towards the axis from the intermediate point to the distal end of the handle. The elongate tubular body comprises a proximal portion and a distal portion, the proximal portion coupled to the distal end of the handle, the distal portion including a distal end of the tubular body. The distal portion comprises a resilient component longitudinally extending along the tubular body proximate to the distal end of the tubular body. The elongate tubular body comprises a lumen extending from the proximal portion to the distal portion and a pull wire extending from the proximal end of the handle to the distal end of the tubular body within the lumen. The method further comprises manually inwardly compressing the handle, extending the proximal end of the handle and the pull wire proximally and deflecting the distal end of the tubular body from a substantially straight configuration to a curved configuration. A degree of deflecting corresponds to a force applied during the manual inward compression. 
     In some embodiments, the method further comprises rotating the handle of the catheter, the distal end of the elongate member rotating during or after manually inwardly compressing the handle. Rotating the handle of the catheter comprises rotating the handle between a thumb and fingers of a user of the catheter. In some embodiments, the method comprises manually decompressing the handle, the handle rebounding towards an unbiased configuration, the proximal end of the handle and the pull wire retracting distally, and deflecting the distal end of the tubular body from a curved configuration to the substantially straight configuration, a degree of deflection corresponding to a force of manual decompression of the handle. The method can comprise locking the pull wire in a proximally extended configuration. 
     For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages are described herein. Of course, it is to be understood that not necessarily all such objects or advantages need to be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that can achieve or optimize one advantage or a group of advantages without necessarily achieving other objects or advantages. 
     All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description having reference to the attached figures, the invention not being limited to any particular disclosed embodiment(s). 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       These and other features, aspects, and advantages of the present disclosure are described with reference to the drawings of certain embodiments, which are intended to illustrate certain embodiments and not to limit the invention. 
         FIG. 1  schematically illustrates an example embodiment of a steerable catheter. 
         FIG. 2  illustrates the steerable catheter of  FIG. 1  in another configuration. 
         FIG. 3  illustrates the steerable catheter of  FIG. 2  in another configuration. 
         FIG. 4  schematically illustrates another example embodiment of a steerable catheter. 
         FIG. 5  illustrates the steerable catheter of  FIG. 4  in a another configuration 
         FIG. 6  schematically illustrates another example embodiment of a steerable catheter. 
         FIG. 7  illustrates the steerable catheter of  FIG. 6  in another configuration. 
         FIG. 8  schematically illustrates another example embodiment of a steerable catheter. 
         FIG. 9  illustrates the steerable catheter of  FIG. 8  in another configuration. 
         FIGS. 10A-10I  illustrate an example embodiment of a method for using a steerable catheter. 
         FIG. 11A  schematically illustrates another example embodiment of a steerable catheter. 
         FIG. 11B  is a cross-sectional view of the steerable catheter of  FIG. 11A  along the line B-B. 
         FIG. 11C  is a cross-sectional view of the steerable catheter of  FIG. 11A  along the line C-C. 
     
    
    
     DETAILED DESCRIPTION 
     Although certain embodiments and examples are described below, those of skill in the art will appreciate that the invention extends beyond the specifically disclosed embodiments and/or uses and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention herein disclosed should not be limited by any particular embodiments described below. 
     Example steerable catheters are provided, each including a handle and an elongate tubular portion. The handle includes multiple segments (e.g., strips, wires), connected at a proximal end of the handle and a distal end of the handle. The segments form a generally arcuate shape such as a sphere or an ellipse. The tubular portion is connected to the distal end of the handle. The tubular portion includes a resilient component positioned near a distal tip of the tubular portion. The resilient component can include a shape-memory material and can extend longitudinally along the tubular portion near the distal tip of the tubular portion. The catheter includes a pull wire fixed to a point near the distal tip of the tubular portion and fixed to a point near the proximal end of the handle. Upon manual compression or squeezing of the handle, the segments are squeezed together, causing the shape of the handle to flatten and lengthen. As the handle lengthens, the pull wire, fixed to the proximal end of the handle, is pulled back, away from the tubular portion. This retraction of the pull wire pulls on the distal tip of the tube portion at the point where the pull wire is fixed to the distal tip of the tubular portion, causing the distal tip of the tubular portion to deflect away from the longitudinal axis of the tubular portion. The deflection may take the form of curvature of the distal tip of the tubular portion. The amount of deflection is proportional to the amount of compression or squeezing of the handle. Increasing the squeezing or compressing of the handle increases the retraction of the pull wire and the deflection of the distal tip. Decreasing the squeezing or compressing of the handle decreases the retraction of the pull wire and the deflection of the distal tip. Upon decompression or release of the handle, the segments of the handle return towards their arcuate configuration and the pull wire moves distally. When no other forces are acting on the resilient component at the distal tip of the tubular member, the resilient component can return to its original configuration, which is usually straight but may also be curved (e.g., curved in the opposite direction to the direction of deflection), and the distal tip can follow the shape of the resilient component. The amount of rebounding is proportional to the amount of decompression or release of the handle. Increasing the decompression or release of the handle increases the distal movement of the pull wire and the amount of rebounding of the distal tip of the tubular portion. Decreasing the decompression or release of the handle decreases the distal movement of the pull wire and the amount of rebounding of the distal tip of the tubular portion. Alternative handles (e.g., including one or more compressible buttons), tubular portions, and other components are also disclosed. 
       FIG. 1  schematically illustrates an example embodiment of a steerable catheter  100 . The steerable catheter comprises a handle  102  positioned at a proximal end of the steerable catheter  100 . The handle  102  comprises a proximal end  106  and a distal end  104 . An axis (not shown) extends between the proximal end  106  and the distal end  104 . The handle comprises a plurality of struts  110  coupled at the proximal end  106  of the handle  102  and at the distal end  104  of the handle  102 . The struts  110  may be biased into an arcuate (e.g., elliptical, spherical, etc.) configuration, as shown in  FIG. 1 . The struts  110  may extend away from the axis from the proximal end  106  of the handle  102  to an intermediate point along the handle  102 . The struts  110  may extend towards the axis from the intermediate point to the distal end  104  of the handle  100 . 
     The steerable catheter  100  comprises an elongate tubular body  112  positioned distally of the handle  102 . The elongate tubular body  112  comprises a proximal portion  114  and a distal portion  116 . A lumen  118  extends from the proximal portion  114  to the distal portion  116 . The distal portion  116  of the tubular body  112  comprises a resilient component  120 . The resilient component  120  is positioned at or near the distal end  122  of the tubular body  112 . The resilient component  120  may extend proximally from a point at or near the distal end  122  of the tubular body  112 . In some embodiments, the elongate tubular body  112  is more malleable towards the distal end  122  of the tubular body  112  than towards the proximal end  114  of the tubular body. This increased malleability can allow enhanced bendability around tortuous anatomy. 
     The steerable catheter  100  comprises a pull wire  124  extending from the proximal end  106  of the handle  102  to the distal end  122  of the tubular body  112 . The pull wire  124  is connected to the handle  102  at or near the proximal end  106  of the handle and is connected to the elongate tubular body  112  at or near the distal end  122  of the body  112 . 
       FIG. 2  depicts the steerable catheter  100  with the distal portion  116  of the tubular body in a deflected position. The handle  102 , including the plurality of struts  110 , is configured to be compressible by a hand of a user. A user may compress the handle within their hand, compressing at least some of the struts  110 . The compression is shown as inward pointing arrows  130  around the handle  102  in  FIG. 2 . In some embodiments, the user compresses all of the struts  110 . In some embodiments, the user compresses only some of the struts  110 . Upon manual inward compression of at least some of the struts  110 , the struts  110  compress from an elliptical or arcuate configuration to a straighter configuration. 
     The degree of straightening of the struts  110  may correspond to the force applied during the manual inward compression of the at least some of the resilient metal struts. For example, increasing the force applied during compression of the struts  110  can increase the degree of straightening. Conversely, decreasing the force applied during compression of the struts  110  can decrease the degree of straightening. 
     Compressing the handle  102  may proximally extend the proximal end  106  of the handle  102 , pulling the pull wire  124  proximally, as shown by the proximally pointing arrow  132  in  FIG. 2 . The degree of the proximal extension of the proximal end  106  of the handle  102  and the pull wire  124  may correspond to the force applied during the manual inward compression of at least some of the struts  110 . For example, increasing the force applied to the struts  110  can increase the proximal extension of the proximal end  106  of the handle  102  and the pull wire. Conversely, decreasing the force applied during manual inward compression of the struts  110  can decrease the proximal extension of the proximal end  106  of the handle  102  and the pull wire  124 . 
     Proximal extension of the pull wire  124  at the distal end  122  of the tubular body causes deflection of the distal portion  116  of the tubular body  112 , shown by the arrow  134  in  FIG. 2 . The degree of deflection may correspond to the force applied during the manual inward compression of at least some of the struts  110 . For example, increasing the force applied to the struts  110  can increase the deflection of the distal portion  116  of the tubular body  112 . Conversely, decreasing the force applied during manual inward compression of the struts  110  can decrease deflection of the distal portion  116  of the tubular body  112 . 
     The distal portion  116  that curves may be defined between the distal end  122  of the catheter  100  and the proximal end of the resilient component  120 . The distal portion  116  may be capable of curving up to 180° within the plane of curvature. The plane of curvature may be a plane including the resilient portion  120  and a section extending along the tubular body  112  that is generally opposite from the resilient portion  120 . 
       FIG. 3  depicts the catheter  100  after decompression of the handle  102 . Decompression of the struts  110  may cause the struts  110  to rebound towards the arcuate configuration, as shown by the outward pointing arrows  136  in  FIG. 3 . The degree of rebounding of the struts  110  may correspond to the force applied during the manual inward decompression (e.g., the force applied when releasing at least some of the struts) of the at least some of the resilient metal struts. For example, increasing the force applied during decompression of the struts  110  can increase the degree of rebounding. Conversely, decreasing the force applied during decompression of the struts  110  can decrease the degree of rebounding. Decompression of the handle  102  causes distal retraction of the proximal end  106  of the handle  102 , shown as distally pointing arrow  138  in  FIG. 3 , allowing the pull wire  124  to retract distally. The degree of the distal retraction of the proximal end  106  of the handle  102  and the pull wire  124  may correspond to the force applied during the decompression of the struts  110 . For example, increasing the force applied during decompression of the struts  110  can increase the distal retraction of the proximal end  106  of the handle  102  and the pull wire. Conversely, decreasing the force applied during manual inward compression of the struts  110  can decrease the proximal retraction of the proximal end  106  of the handle  102  and the pull wire  124 . 
     Distal retraction of the pull wire  124  allows the distal portion  116  of the tubular body to rebound from a deflected or curved configuration towards a straighter configuration, shown by arrow  140  in  FIG. 3 . Distal retraction of the pull wire  124  decreases the deflecting force applied to the resilient component  120 . With less deflecting force acting upon the resilient component  120 , it rebounds to its original (e.g., straight) position. The degree of rebounding of the distal portion  116  may correspond to a force applied during decompression of the handle  102 . For example, increasing the force applied during decompression of the struts  110  can increase the rebounding of the distal portion  116 . Decreasing the force applied during decompression of the struts  110  can decrease rebounding of the distal portion  116 . 
     The deflection and rebounding of the distal portion  116  of the tubular body  112  can allow the catheter  100  to be navigated through tortuous sections of the anatomy (e.g., the vasculature). This ability to navigate can allow the catheter  100  to be used as a guiding catheter for use in peripheral vasculature or coronary sinus areas, implant delivery systems, and for EP mapping, among other applications. Many steerable catheters currently available use some sort of handle, lever, or motor/switch system by which they cause the distal end of the catheter to curve. Such configurations do not allow for optimal control over the steering or provide tactile feedback to the physician attempting to steer the catheter. Furthermore, some “digital” steering mechanisms do not provide any tactile feedback or allow for fine control in response to the anatomy encountered during a medical procedure. This compression and decompression can be described as “analog” because there are an infinite number of positions the pull wire can be extended to and an infinite number of curvatures that can be imparted to the distal portion. By contrast, existing structures can generally only be operated in two “digital” predetermined curvatures (one of which may be no curvature). In the case of currently available “analog” steering mechanisms, one finger or thumb is generally used to steer the catheter, which provides less than ideal tactile feedback and can be difficult to control consistently. In contrast, the steering mechanism disclosed herein is controlled by an analog, compressible handle  102  configured to be grasped by the hand (e.g., thumb, palm, and at least some fingers) of a user. Parts of the hand working together can allow for increased tactile feedback and control over currently available systems. 
     In some embodiments, the catheter  100  comprises more than one lumen extending from the proximal portion  114  to the distal portion  116 . The pull wire may be housed within a “false” lumen. The catheter may also comprise one or more working or functional lumens. For some examples, a guidewire, other catheters, devices (e.g., endoluminal devices), therapeutic agents, or a wire for EP applications could be navigated through these working or functional lumens. The lumens may be side-by-side, coaxial, round, partially round (e.g., wedges, semicircular, crescent, etc.). 
     In some embodiments, the struts  110  comprise a wire. Other shapes for the struts are also possible. For example, in some embodiments, the struts  110  comprise a ribbon. In some embodiments, all of the struts  110  comprise a same shape. In other embodiments, the struts  110  comprise different shapes. For example, some of the struts  110  may comprise a wire and others of the struts  110  may comprise a ribbon. 
     The struts  110  comprise a resilient and flexible material. In some embodiments, the struts  110  comprise a shape memory material. In some embodiments, the struts  110  comprise a metal. The struts  110  may comprise a nickel-titanium alloy (e.g., Nitinol). In some embodiments, the struts  110  comprise a polymer (e.g., carbon fiber). Other resilient and flexible materials are also possible. In some embodiments, the struts  110  comprise the same material. In some embodiments, the struts  110  comprise different materials. For example, some (e.g., half) of the struts may comprise Nitinol, and the remaining struts  110  may comprise carbon fiber, stainless steel, etc. For another example, one strut of the plurality of struts  110  may comprise Nitinol, and the remainder of the struts  110  may comprise carbon fiber, stainless steel, etc. 
     In some embodiments, the handle  102  comprises a cover over the plurality of struts  110 . A cover positioned over the handle  102  can enhance the ease of use and comfort of the handle  102  for a user. For example, the cover can prevent pinching of the user&#39;s hands upon movement of the strips. The cover can also provide a textured surface that is easier to manipulate than the strips. In some embodiments, the cover comprises silicone. Other materials (e.g., other polymers and plastics) are also possible. 
     In some embodiments, the resilient component  120  comprises a shape memory material. For example, the resilient component  120  can comprise a nickel titanium alloy (e.g., Nitinol). In some embodiments, the resilient component  120  comprises a ribbon. Other shapes are also possible. For example, the resilient component  120  can comprise a wire. Other materials comprising rebound tensile strength (e.g., springs) are also possible. In some embodiments, the resilient component  120  is continuous along a portion of the tubular body  112 . In some embodiments, the resilient component comprises multiple discrete components within the tubular body  112 . In some embodiments, the catheter  100  comprises multiple resilient components  120 . In some embodiments, a number, shape, and material of resilient components can be used to affect a rigidity of the catheter  100 . For example, multiple resilient components or a more rigid material in the resilient component can involve a greater compressive force on the handle of the catheter to deflect the distal portion  116  of the catheter  100 . 
     In some embodiments, the resilient portion  120  is pre-curved in a first direction by curving the resilient component  120 . In such embodiments, compressing the handle  102  causes the distal portion  116  of the catheter to curve in a second direction, which may be opposite to the first direction. In embodiments comprising a pre-curved resilient portion  120 , curvature of the distal portion  116  up to 360° within the plane of curvature may be possible. 
       FIG. 4  schematically illustrates another example embodiment of a steerable catheter  400 . Unless otherwise noted, the catheter  400  comprises features similar to the catheter described with respect to  FIGS. 1-3 . The catheter  400  comprises a handle  402  comprising a depressible portion or bump  404 . The depressible portion or bump  404  is connected to a pull wire  424  extending from the bump  404  to a distal end  422  of the catheter  400 . The catheter  400  comprises a pulley or rod  406 , on which the pull wire  424  rests. Like the catheter  100  shown in  FIG. 1 , the catheter  400  comprises a resilient portion  420  at the distal end  422  of the catheter  400 . 
     A finger may be used to depress the bump  404 . For example, the thumb or index finger may be used to depress the bump  404 , which may allow for greater accuracy and tactile feedback than using other fingers or an entire hand. 
       FIG. 5  depicts the catheter  400  while the bump  404  is being depressed, shown by arrow  430  in  FIG. 5 . Depression of the bump  404  causes proximal extension of the pull wire  424  around the pulley  406  and down. A degree of proximal extension of the pull wire corresponds to the downward extension of the bump  404  and the downward extension of the pull wire  424  around the pulley  406 . Increasing the downward extension of the pull wire  424  around the pulley  406  may increase the proximal extension of the pull wire  424 . Proximal extension of the pull wire  424  at the distal end  422  of the catheter  400  causes deflection of a distal portion  416  of the catheter  400 , shown by arrow  434 . A degree of deflection corresponds to a force applied during depression of the bump  404 , for example as described with respect to catheter  100 . Increasing the proximal extension of the pull wire  424  (e.g., by increasing the downward extension of the bump  404 ) can increase the deflection of the distal portion  416  of the catheter  400 . 
     Release of the bump  404  can cause distal retraction of the pull wire  424  and allow rebounding of the distal portion  416  of the catheter  400 , for example as described above with respect to the catheter  100 . Distal retraction of the pull wire  424  decreases the deflecting force applied to the resilient component  420 . With less deflecting force acting upon the resilient component  420 , it rebounds to its original (e.g., straight) position. In some embodiments, the catheter  400  comprises a resilient component (e.g., a spring) below the bump  404 . In such an embodiment, the downward extension of the bump  404  may cause proximal extension of the pull wire  424 , as described above. Upon release of the bump  404 , the resilient component may cause the bump  404  to rebound towards its original position, which may retract the pull wire  424  and may cause the distal portion  416  to return to a straighter configuration. In certain such embodiments, the catheter  400  optionally does not include a resilient component at its distal end, as the resilient component at the bump  404  may control the rebounding. 
     In some embodiments, the catheters disclosed herein comprise multiple pull wires. For example the catheters can comprise 1, 2, 3, 4, or more pull wires. The pull wires can be connected to pull wire fix points near or at the distal end of the catheter. In some embodiments, the pull wire fix points can be spaced circumferentially around a circumference of the tubular body (e.g.,  112  proximate to the distal end  122  of the tubular body  112 ). In such embodiments, the different pull wires may be used to deflect the catheter in different directions. 
       FIG. 6  schematically illustrates an example embodiment of a steerable catheter  600 . The catheter  600  is similar to the catheter  400 , shown in  FIGS. 4 and 5 , but the catheter  600  comprises a handle  602  comprising a first bump  604  and a second bump  605 . The catheter  600  also comprises a first pull wire  624  and a second pull wire  625 . The catheter  600  optionally comprises a resilient component  620  positioned at a distal portion  616  of the catheter  600 . The multiple pull wires with separate controls can allow for deflection of the distal portion  616  of the catheter  600  in multiple directions. 
     As shown in  FIG. 6 , depressing the top bump  604  extends the top pull wire  624  proximally and around the top pulley or rod  606 . The proximal extension of the pull wire  624  at the distal end  622  of the catheter  600  causes the distal portion  616  of the catheter  600  to deflect upwards shown by arrow  630  in  FIG. 6 . 
     Releasing the bump  604  causes the pull wire  624  to move upwards around the pulley  606 , and can cause distal retraction of the pull wire  624 . The distal retraction of the pull wire  624  can cause the distal portion  616  of the catheter  600  to rebound towards a straighter configuration. The rebounding may be caused by a resilient component positioned at the distal portion  616  of the catheter  600 . In some embodiments, the rebounding may be caused by a resilient component under the bump  604 . In some embodiments, the rebounding may be caused by deflecting the pull wire  624  in a different direction by pressing the bump  605 , as described below. 
       FIG. 7  illustrates the catheter  600  when the bottom bump  605  is depressed. Depressing the bottom bump  605  extends the bottom pull wire  625  proximally and upwards around the bottom pulley or rod  607 . The proximal extension of the pull wire  625  at the distal end  622  of the catheter  600  causes the distal portion  616  of the catheter  600  to deflect downwards shown by arrow  632  in  FIG. 7 . Releasing the bump  605  can cause the pull wire  625  to move downwards around the pulley  607 , retracting the pull wire  625  distally. Distal retraction of the pull wire  625  can cause the distal portion  616  of the catheter  600  to rebound towards a straighter configuration. The rebounding may be caused by a resilient component positioned at a distal portion  616  of the catheter  600 . The rebounding may be caused by a resilient component above the bump  607 . In some embodiments, the rebounding may be caused by deflecting the pull wire  625  in a different direction by pressing the bump  604 . 
     In some embodiments, the catheter comprises more than two bumps and two pull wires, which can allow the distal end of the catheter to be steered by deflecting the distal portion in additional directions without rotation of the catheter. It will be appreciated that the bumps can comprise different shapes than those shown in  FIGS. 6 and 7 . 
       FIG. 8  schematically illustrates another example embodiment of a steerable catheter  800 . The catheter  800  comprises a handle  802 , for example similar to that described with respect to the catheter  100  of  FIGS. 1-3 . The handle  802  comprises a proximal end  806  and a distal end  804 . The handle  802  comprises a plurality of struts  810  coupled at the proximal end  806  of the handle  802  and at the distal end  804  of the handle  802 . The struts  810  may be biased into an arcuate (e.g., elliptical, spherical, etc.) configuration. The struts  810  extend away from the axis from the proximal end  806  of the handle  802  to an intermediate point along the handle  802 . The struts  810  extend towards the axis from the intermediate point to the distal end  804  of the handle  800 . 
     The steerable catheter comprises an outer elongate body  812  and an inner elongate body  813 . A proximal end of the outer elongate tubular body  812  may be connected to the proximal end  806  of the handle  802 . A proximal end of the inner elongate tubular body  813  may be connected to the distal end  804  of the handle  802 . The outer elongate tubular body  812  may include slits (not shown) that allow the struts  810  to be connected to the inner elongate tubular body through the outer body  812 . A distal portion  816  of the inner body  813  may be pre-shaped in a particular configuration (e.g., curved). The distal portion  816  of the tubular body  813  may comprise a resilient component (not shown), for example similar to any of the resilient components  120 ,  420 ,  620 , that has been pre-shaped. The distal portion  816  may be housed within the straight outer body  812 . 
       FIG. 9  shows the catheter  800  during compression of the handle  802 . Compression of the handle  802  or at least some of the struts  810  can proximally extend the proximal end  806  of the handle proximally, as shown by arrow  830  in  FIG. 9 . The proximal extension of the distal end  806  of the handle  802  may cause the outer tubular body  812  to extend proximally. The inner body  813 , which is not connected to the proximal end  806  of the handle  802 , does not extend proximally along with the outer body  812 . The proximal movement of the outer tubular body  812  may cause the distal portion  816  of the inner tubular body  813  to emerge or prolapse from the distal end of the outer body  812 . Without the outer tubular body  812  biasing the distal portion  816  of the inner tubular body  813  into a straight configuration, the distal portion  816  can return to its pre-shaped configuration, as shown by arrow  832 . 
     Decompression of the handle  802  allows the proximal end  806  of the handle  802  to retract distally. Decompression of the handle  802  causes at least some of the struts  810  to return to a straighter configuration. Some of the struts  810  returning to a straighter configuration can cause the proximal end  806  of the handle  802  to retract distally. The distal retraction of the proximal end  806  of the handle  802  causes the outer tubular body  812  to retract distally. The distal retraction of the outer tubular body causes the inner tubular body  813  to be sheathed within the outer tubular body  812 , causing the distal portion  816  to return to a straight configuration. 
     Configurations for the pull wire and sleeve other than those shown in  FIGS. 8 and 9  are also possible. For example, in some embodiments, instead of retracting the outer tubular body, the inner tubular body may be pushed out of the outer body, which may also cause the distal portion of the inner body to return to its pre-shaped configuration. It will be appreciated that, in some embodiments, the sleeve and the inner catheter can be fixed using other fixation modalities. For example, a pull wire may connect the outer catheter to the proximal end of the handle. Metal strips, plastic strips, or tubes may also be used. For another example, the sleeve may be directly fixed to the proximal end of the grip. Other configurations are also possible. 
       FIGS. 10A-10I  schematically illustrate an example embodiment of a method of rotating a catheter  1000  comprising a handle  1002  similar to the handles (e.g., handles  102 ,  802 ) described above. Once the catheter  1000  has been advanced to a location requiring steering of the catheter, the handle  1002  is squeezed. As described above with respect to the catheter  100 , compression of the handle  1002  causes the pull wire, which is fixed to the proximal end of the handle  1002 , to extend proximally, deflecting the distal tip  1004  of the catheter. As described above with respect to the catheter  800 , compression of the handle  1002  causes the outer tube, which is fixed to the distal end of the handle  1002 , to extend proximally and allow prolapse of the inner tube, deflecting the distal tip  1004  of the catheter. In some embodiments, for example, when navigating through tortuous anatomy (e.g., the vasculature), after deflecting the distal tip  1004  of the catheter  1000 , the anatomy may require the user to steer the catheter  1000  in another direction. Rotating the catheter  1000  around a longitudinal axis by rotating the handle  1002  can allow the user to steer the catheter  1000  in a different direction with the distal tip  1004  in a curved configuration. 
       FIG. 10A  depicts the handle  1002  being squeezed between the thumb  1006  and the fingers  1008  of the user, causing the distal tip  1004  to deflect. Other configurations for squeezing the handle  1002  are also possible. For example, a user may squeeze the handle  1002  with a palm or the arch between the thumb and the index finger. In  FIG. 10B , the user maintains pressure on the handle  1002 , keeping the distal tip  1004  deflected, and moves the thumb  1006  forward (or downward as shown on the page) and/or moving the fingers  1008  backwards (or upward as shown on the page).  FIGS. 10C-10E  show the thumb  1006  continuing to move forwards and/or the fingers  1008  continuing to move backwards, or a combination thereof. As the handle  1002  rotates within the hand of the user, the distal tip  1004  of the catheter  1000  also rotates. It will be appreciated that the user can rotate the handle  1002  in various ways. For example, the user my instead extend the fingers while retracting the thumb. 
     In some embodiments, the catheter is sufficiently rigid for the distal tip  1004  of the catheter to equally match the rotation of the handle  1002 . In some embodiments, the distal tip  1004  of the catheter  1000  does not rotate at the same rate as the handle  1002 . 
       FIG. 10F  depicts the user maintaining pressure on the handle  1002  using the fingers  1008 , but moving the thumb backwards to allow for further rotation. The thumb  1006  is now in a similar position as was shown in  FIG. 10A .  FIGS. 10G-10I  depict the thumb  1006  extending and/or the fingers  1008  retracting, rotating the catheter  1000 , including the distal tip  1004 . As shown in  FIGS. 10A-10I , the catheter  1000  is capable of at least 360° of rotation. Using the method depicted in  FIGS. 10A-10I , the catheter  1000  can be rotated greater than 360°. Although shown in  FIGS. 10A-10I  as always being in a substantially similar curved configuration throughout the rotation, the distal tip  1004  may be further curved and/or straightened during the rotation, for example based on tactical sensation. 
       FIG. 11A  schematically illustrates an example embodiment of a catheter  1100  comprising an optional locking mechanism. Unless otherwise described, the catheter  1100  is similar to the catheter  100  described with respect to  FIG. 1 . The catheter  1100  comprises a handle  1102  positioned at a proximal end of the steerable catheter  1100 . The handle  1102  comprises a proximal end  1106  and a distal end  1104 . An axis (not shown) extends between the proximal end  1106  and the distal end  1104 . The handle comprises a plurality of struts  1110  coupled at the proximal end  1106  of the handle  1102  and at the distal end  1104  of the handle  1102 . The struts  1110  may be biased into an arcuate (e.g., elliptical, spherical, etc.) configuration, as shown in  FIG. 1 . The struts  1110  extend away from the axis from the proximal end  1106  of the handle  1102  to an intermediate point along the handle  1102 . The struts  1110  extend towards the axis from the intermediate point to the distal end  1104  of the handle  1102 . 
     The steerable catheter  1100  comprises an elongate tubular body  1112  positioned distally of the handle  1102 . The elongate tubular body  1112  comprises a proximal portion  1114  and a distal portion  1116 . A lumen  1118  extends from the proximal portion  1114  to the distal portion  1116 . The distal portion  1116  of the tubular body  1112  comprises a resilient component  1120 . The resilient component  1120  is positioned at or near the distal end  1122  of the tubular body  1112 . The resilient component  1120  may extend proximally from a point at or near the distal end  1122  of the tubular body  1112 . In some embodiments, the elongate tubular body  1112  is more malleable towards the distal end  1122  of the tubular body  1112  than towards the proximal end  1114  of the tubular body. 
     The steerable catheter  1100  comprises a pull wire  1124  extending from the proximal end  1106  of the handle  1102  to the distal end  1122  of the tubular body  1112 . The pull wire  1124  is connected to the handle  1102  at or near the proximal end  1106  of the handle and is connected to the elongate tubular body  1112  at or near the distal end  1122  of the body  1112 . 
     The catheter  1100  comprises a first disk  1140  and a second disk  1144  at or near the distal end  1104  of the handle  1102 . The first disk  1140  comprises a latch  1142 . In some embodiments, the first disk  1140  comprises a greater diameter than the second disk  1144 . In some embodiments, the disks  1140 ,  1144  have the same diameter. In some embodiments, the first disk  1140  comprises a smaller diameter than the second disk  1144 .  FIG. 11A  depicts the first disk  1140  comprising a smaller thickness along the length of the catheter  1000  than the thickness of the second disk  1144 . In some embodiments, the first disk  1140  comprises a greater thickness than the second disk  1144 . In some embodiments, the first disk  1140  comprises a same thickness as the second disk  1144 . The first disk  1140  is depicted as being positioned over or around two parts of the second disk  1144 . In some embodiments, the first disk  1140  is proximal or distal to the second disk  1144 . In some embodiments, the disks  1140 ,  1144  are adjacent. In some embodiments, the disks  1140 ,  1144  may be spaced from one another. 
       FIG. 11B  schematically depicts a cross-sectional view of the second disk  1144  taken along the line B-B. The second disk  1144  may comprise a cross sectional shape similar to the shape of the cross section of the catheter  1000 . Other shapes (e.g., square-shaped or elliptical) are also possible. The second disk  1144  comprises a central bore  1150  configured to permit the passage of one or more lumens through the disk  1144 . The central bore  1150  is shown as circular, but other shapes are also possible. For example, the central bore  1150  can be ovular or rectangular. The second disk  1144  comprises an eccentric aperture  1148  configured to permit passage of the pull-wire  1124  therethrough. The aperture  1148  is shown as circular, but other shapes (e.g., ovular) are also possible. The second disk  1144  comprises a notch  1146  shaped to mate with the latch  1142  of the first disk  1140 . The notch  1146  is shown as rectangular, but other shapes (e.g., triangular, circular) are also possible. 
       FIG. 11C  schematically illustrates a cross-sectional view of the first disk  1140  taken along the line C-C. The first disk  1140  comprises a cross sectional shape similar to the shape of the cross section of the catheter  1000 . Other shapes (e.g., square-shaped or elliptical) are also possible. The second disk  1140  comprises a central bore  1152  configured to permit the passage of one or more lumens through the disk  1140 . The central bore  1152  is shown as circular, but other shapes are also possible. For example, the central bore  1152  can be ovular or rectangular. The first disk  1140  comprises an eccentric aperture  1154  configured to permit passage of the pull-wire  1124  therethrough. The aperture  1154  is shown as circular, but other shapes (e.g., ovular) are also possible. The first disk  1140  and second disk  1144  are shown as having central bore  1150 ,  1152  of the same size and shape, but they may be different. The central bores  1150 ,  1152  may be sized to permit passage of any lumens therethrough. The central bore  1152  may be the size of the central bore  1150  plus the thickness of the second disk  1144 . In some embodiments, the apertures  1148 ,  1154  comprise different shapes and sizes. The apertures  1148 ,  1154  may have a shape and size selected to permit the passage of a pull wire therethrough. The first disk  1140  comprises a latch  1142  shaped to fit within the notch  1146  of the second disk  1144 . 
     After the distal tip  1116  of the catheter has been deflected, as described above with respect to  FIG. 2 , the first and second disks  1140 ,  1144  can be used to lock the distal tip  1116  in a deflected position by holding the pull wire  1122  in a proximally extended position. Prior to deflecting the distal portion  1116  of the catheter  1100 , the first disk  1140  can be rotated to a position where the pull wire apertures  1148 ,  1154  are in alignment. After deflection of the distal tip  1116  of the catheter  1100 , the first disk  1140  can be rotated relative to the second disk  1144 , creating friction on the pull wire as the pull wire apertures  1148 ,  1154  move out of alignment. Once sufficient friction is put on the pull wire  1122 , the latch  1142  may be locked into the notch  1146 , holding the disks  1140 ,  1144  in an unaligned position and the distal tip  1116  in a deflected position. Locking the catheter  1100  in a deflected position may allow for ease in rotating and steering the catheter, for example because inward pressure on the handle  1102  is not needed to deflect the distal portion  1116 . 
     The first disk  1140  is rotatable relative to the second disk  1144 . The second disk  1144  may be fixed in position relative to the catheter  1100 , or a portion of the catheter  1000 . In some embodiments, both disks  1140 ,  1144  may be rotatable. Other means for locking the pull wire  1124  in position are also possible For example, the catheter  1100  may comprise a collar positionable around the handle  1102 . For another example, the pull wire  1124  may comprise hook-like structures that may engage with other hook like structures of the catheter  1100  (e.g., at the distal end  1104  of the handle  1102 ). 
     Although this invention has been disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while several variations of the embodiments of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the embodiments of the disclosed invention. Thus, it is intended that the scope of the invention herein disclosed should not be limited by the particular embodiments described above.