Steerable medical devices and related methods

Abstract

The medical device (10) comprises a handle (12) including a handle body (24) and an actuator (26), and a shaft (14) extending distally from the handle body, the shaft being constructed from a shape memory material, the shaft including a proximal section (32) and a distal section (349), the proximal section having a first austenite finish temperature and the distal section having a second austenite finish temperature, the first austenite finish temperature being lower than the second austenite finish temperature.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to devices and methods for steerable medical devices. More specifically, aspects of the disclosure relate to devices and / or methods for steerable guidewires. [Background technology]

[0002] Medical procedures involving navigation to a site within the body often require a medical guidewire. Guidewires are used in various catheterization procedures and other medical procedures as an aid in placing catheters and other devices at selected sites in the human body. Guidewire navigation often requires navigating and / or steering the guidewire through complex and tortuous anatomical structures until the desired anatomical structure is reached. Guidewires may include a steerable distal portion or tip that can be steered / articulated by a user via a controller. To impart such steerable behavior, the distal portion of the guidewire may be cut into various patterns to control its stiffness. This cutting process may require the use of a diamond saw or laser, which may be time-consuming and / or expensive. Summary of the Invention

[0003] The present disclosure relates, among other things, to devices and methods for steerable medical devices. Each example disclosed herein may include one or more of the features described in connection with any of the other disclosed examples.

[0004] According to one aspect, a medical device may include a handle including a handle body and an actuator, and a shaft extending distally from the handle body. The shaft may include a shape memory material. The shaft may include a proximal section and a distal section. The proximal section may include a first austenite finish temperature and the distal section may have a second austenite finish temperature. The first austenite finish temperature may be lower than the second austenite finish temperature.

[0005] In another aspect, the shaft may further include a transition section between the proximal section and the distal section, the transition section may include a proximal portion having an austenite finish temperature close to or higher than the first austenite finish temperature, and the transition section may further include a distal portion having an austenite finish temperature close to or lower than the second austenite finish temperature.

[0006] In another embodiment, the first austenite finish temperature can be at or below body temperature and the second austenite finish temperature can be above body temperature. In another aspect, the distal section may include at least one depression. The at least one depression may be a concave cutout, and the at least one depression may span at least a portion of the circumference of the distal section. The at least one depression may span the entire circumference of the distal section. The distal section may include a bendable portion. The bendable portion may be of a smaller circumference than the remainder of the distal section, and the bendable portion may be a portion of the distal section having the thinnest profile.

[0007] In another aspect, the distal section may include a plurality of indentations. The distal section may include a first indentation and a second indentation. The first indentation and the second indentation may have different shapes, and the bending profile of the first indentation may be different from the bending profile of the second indentation. The first indentation may be a concave cutout and the second indentation may be a V-shaped cutout. Each of the first indentation and the second indentation may span a range of about 20° to about 170° around the circumference of the distal section. The at least one indentation may be laser cut.

[0008] In another aspect, the medical device may further include a plurality of steering elements, each of which may extend through the shaft between the actuator and the distal section.

[0009] Alternatively, both the first austenitic finish temperature and the second austenitic finish temperature may be set by heat treating the proximal and distal sections of the shaft.

[0010] According to another aspect, the medical device may include a shaft extending distally from the handle body. The shaft may include a shape memory material. The shaft may include a proximal section and a distal section. The proximal section may have a first austenite finish temperature and the distal section may have a second austenite finish temperature, the first austenite finish temperature being lower than the second austenite finish temperature. The distal section may include a first indentation defining a first bend profile and a second indentation defining a second bend profile, the first bend profile being different from the second bend profile. The first bend profile may be a gradual U-shaped bend and the second bend profile may be an abrupt V-shaped bend. The first and second indentations may each span a range of about 20° to about 170° around the circumference of the distal section. The first austenite finish temperature may be below body temperature and the second austenite finish temperature may be above body temperature.

[0011] According to another aspect, a method of using a medical device may include a handle and a shaft, the handle may include an actuator, the shaft may include a distal section, the distal section may include a first depression and a second depression, the actuator may be coupled to the distal section via at least one steering element, the method may include delivering the shaft into a body lumen, positioning the distal section of the shaft adjacent to a target site, actuating the actuator to bend the distal section about the first depression with a first bending profile, and actuating the actuator to bend the distal section about the second depression with a second bending profile, the first bending profile may be different from the second bending profile.

[0012] It will be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. As used herein, the terms "comprising," "having," "including," or other variations thereof are intended to cover a non-exclusive inclusion, and a process, method, article, or apparatus that includes a list of elements does not include only those elements, but may include other elements not expressly listed or inherent in such process, method, article, or apparatus. The term "exemplary" is used in the sense of "example," rather than "ideal." The term "approximately" or similar terms (e.g., "substantially") include values ​​of ±10% of the stated value. [Brief explanation of the drawings]

[0013] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and, together with the description, serve to explain the principles of the present disclosure. [Figure 1] 1 illustrates a side view of an exemplary medical device. [Figure 2] 2 shows a side view of a distal portion of the exemplary medical device of FIG. 1. [Figure 3] 2 shows a cross-sectional view of a distal portion of the exemplary medical device of FIG. 1. [Figure 4] 1 shows a cross-sectional view of a distal portion of another exemplary medical device. [Figure 5] 5 shows a flowchart of the operation of the exemplary medical device of FIGS. 1 and 4. DETAILED DESCRIPTION OF THE INVENTION

[0014] Detailed Description Embodiments of the present disclosure aim to provide a medical device including a steerable shaft, such as a guidewire. The guidewire of the present disclosure can be manufactured more easily and at a lower cost than existing guidewires that include multiple cuts alternating along the length of the guidewire, for example, in a diamond-cut pattern. The guidewire of the present disclosure can include a shape memory material, such as nitinol, that has undergone a heat treatment or thermal cycling process. Applying heat to the shape memory material imparts various properties, such as superelasticity and / or malleability, to the heated portion of the guidewire, thereby providing varying stiffness throughout the length of the guidewire.

[0015] Shape memory materials can transform between at least two states: martensitic and austenitic. Specifically, when the temperature to which the material is exposed decreases, the material transforms from the austenitic state to the martensitic state; similarly, when the temperature to which the material is exposed increases, the material transforms from the martensitic state to the austenitic state. The temperature at which the transformation from the austenitic state to the martensitic state begins is commonly referred to as the Ms (martensite start temperature), and the temperature at which this transformation ends is commonly referred to as the Mf (martensite finish temperature). As a material transforms from the austenitic state to the martensitic state, it becomes more deformable. In the martensitic state, the material can accommodate large deformations at low stress levels. This material exhibits malleable properties. This malleability allows the material to flex and deform when force is applied, making it less likely to fracture. Therefore, the material can withstand significant deformation before reaching its failure point.

[0016] When a material in the martensite state is heated, it begins to transform into the austenite state. The temperature at which this transformation begins is called the austenite start temperature (As). The transformation is complete at a temperature called the austenite finish temperature (Af). The material continues to tolerate deformation until it reaches Af, and may exhibit malleable properties. However, when the material is heated to Af, the mechanical properties of the material change, and the material exhibits superelasticity. Superelasticity can be defined as the ability of a shape memory material to recover from deformation. Therefore, shape memory materials heated to Af may exhibit higher stiffness, indentation strength, and column strength compared to shape memory materials at temperatures below Af.

[0017] The Af of a shape memory material can be altered and / or set to a particular temperature by a heat treatment or thermal cycling process. Thus, in some examples, a guidewire including a shape memory material can be heat treated to set a particular Af (e.g., body temperature, a temperature above body temperature, etc.) for the guidewire. In other examples, different portions of the guidewire can be subjected to different heat treatments, each with a different Af, resulting in different stiffnesses throughout the length of the guidewire. The heat treatment or thermal cycling process for setting the Af is not particularly limited and can be any suitable heat treatment or thermal cycling process known in the art.

[0018] While the present disclosure refers to guidewires used in conjunction with endoscopic, colonoscopic, and / or ERCP procedures, it will be understood that guidewires can also be utilized in other types of procedures, including intracardiac, coronary, central circulatory system, peripheral vascular, and neurovascular or urological procedures. The medical devices disclosed herein can have a handle coupled to the proximal end of a shaft, such as a guidewire. The shaft has at least two degrees of freedom of motion. The shaft can be articulated (e.g., curved or deflected) in one or more directions. Additionally, the shaft can be rotatable and moveable proximally and distally. The handle can be detachable from the shaft, facilitating the use of the guidewire to guide a tool or medical device after placement. The shaft can include a lumen with one or two articulation wires, one or both of which can be used to achieve the desired steering / articulation of the shaft. The medical devices disclosed herein can be used in combination with a duodenoscope, endoscope, colonoscope, ureteroscope, gastroscope, bronchoscope, laparoscope, sheath, catheter, or other suitable delivery device. Additionally, the disclosed medical devices can be compatible with robotic platforms.

[0019] Reference will now be made in detail to the embodiments of the present disclosure described above and illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. As used herein, the terms "proximal" and "distal" are used to refer to the relative locations of components of exemplary medical devices. As used herein, "proximal" refers to a location relatively closer to an operator using the medical device, whereas "distal" refers to a location relatively further from an operator using the medical device.

[0020] FIG. 1 illustrates an exemplary medical device 10. As shown in FIG. 1, the medical device 10 may include a handle 12 and a shaft 14. The handle 12 is not particularly limited and may be any suitable handle capable of steering or controlling various aspects of the shaft 14. For example, the handle 12 may include at least a body 24, an actuator 26, and a collet 28. As shown in FIG. 1, the body 24 extends longitudinally. However, the body 24 is not particularly limited and may be any suitable shape or size. The portion of the body 24 not bound by the actuator 26 may be held in a user's hand. The body 24 may include additional features or aspects (not shown) that engage and retain the actuator 26 and the collet 28.

[0021] The actuator 26 may be any suitable actuator (e.g., a spool, slider, knob, etc.) coupled to and / or movable relative to a portion of the body 24. The actuator 26 may be actuated by any suitable means. For example, the actuator 26 may be rotatable clockwise or counterclockwise relative to the body 24. In another example, the actuator 26 may be slidably movable proximally and / or distally along the body 24. The actuator 26 may be coupled to one or more steering elements 56 (shown in FIG. 3 ). For example, one embodiment of the actuator 26 may be coupled to a proximal end of the steering element 56, e.g., within an internal passageway of the body 24.

[0022] The actuator 26 may be coupled to the proximal end of the steering element 56 via, for example, a friction fit, adhesive, press fit, crimping, or other suitable coupling mechanism. In this embodiment, movement of the actuator 26 relative to the body 24 can control tension on one or more steering elements 56, thereby controlling steering of the distal portion 34 of the shaft 14. The number of steering elements 56 is not particularly limited (e.g., one or more steering elements 56), and the number of steering elements 56 can correlate to the number of different directions in which the shaft 14 can articulate. Additionally, although not shown, the handle 12 can further include one or more springs or biasing elements, for example, within the lumen of the body 24, to bias the movement actuator 26. For example, the one or more springs or biasing elements can bias the actuator 26 to a default position in which no force is applied to any of the steering elements 56, thereby maintaining the distal portion 34 in a neutral, unbent configuration. Additionally or alternatively, one or more portions of the handle 12 may include a locking mechanism for selectively and / or releasably securing the position of the actuator 26, for example.

[0023] The collet 28 may be disposed at the distal end of the body 24. As shown in FIG. 1 , the collet 28 may have a conical shape that tapers distally, but is not necessarily limited to this. The collet 28 may include a distal opening (not shown) that receives and retains the proximal portion of the shaft 14. The manner in which the collet 28 retains the shaft 14 is not particularly limited (e.g., friction fit, etc.). The collet 28 may removably retain the proximal portion of the shaft 14, allowing the user to remove or separate the handle 12 from the shaft 14 by any suitable means after delivering the shaft 14 to the target anatomical structure.

[0024] Shaft 14 may be a wire or tubular structure (e.g., a guidewire) including an annular body 144 defining a lumen 142 (shown in FIG. 3). Shaft 14 may have any suitable outer width (e.g., diameter). For example, the outer width (e.g., diameter) of shaft 14 may be similar to or the same as a typical guidewire. Exemplary outer diameters may range from about 0.25 mm to about 1.0 mm (about 0.010 inches to about 0.04 inches), or more specifically, from about 0.36 mm to about 0.81 mm (about 0.014 inches to about 0.032 inches). The outer diameter may be constant along the length of shaft 14 or may vary as shown in FIGS. 2 and 3 and described in further detail below.

[0025] The shaft 14 may include a proximal section 32, a transition section 33, and a distal section 34, as shown in FIGS. 1 and 2 . Additionally, the shaft 14 may include a distal end 38. The distal end 38 is not particularly limited, and in some examples, may include a radiopaque marker that is visible under imaging, e.g., X-ray. A proximal portion of the proximal section 32 may be engaged and retained within the collet 28. The distal section 34 may be coupled to the distal end of a steering element 56 ( FIG. 3 ) via, for example, a friction fit, adhesive, a press fit, a crimp, or other suitable coupling mechanism. In this embodiment, the articulation or steering of the distal section 34 of the shaft 14 may be controlled by manipulating (e.g., retracting and / or pulling proximally) the steering element 56 via the actuator 26.

[0026] Each section 32, 33, 34 of the shaft 14 may comprise nitinol and / or other shape memory material. Furthermore, as noted above, the proximal section 32 and the distal section 34 may each undergo a different heat treatment or thermal cycling process, resulting in a different Af for each of the sections 32, 34. For example, the proximal section 32 may undergo a first heat treatment to set the Af of the proximal section 32 to a first temperature (e.g., body temperature (approximately 36.2°C to approximately 37.2°C) or a temperature lower than body temperature). The distal section 34 may also undergo a second heat treatment to set the Af of the distal section 34 to a second temperature (e.g., a temperature higher than body temperature). The order of the first and second heat treatments is not particularly limited.

[0027] As a result of differential heat treatment, when both the proximal section 32 and the distal section 34 are heated to a first temperature or a second temperature, but not the other temperature, the proximal section 32 and the distal section 34 may exhibit different mechanical properties. For example, when the first temperature (e.g., Af of the proximal section 32) is at or below body temperature, the proximal section 32 may exhibit superelasticity when inserted into the body and exposed to body temperature. Such superelasticity may help improve the pushability and column strength of the proximal section 32, allowing the shaft 14 to be manipulated and / or advanced through tortuous anatomical structures while reducing the likelihood of buckling or deformation of the proximal section 32. When the second temperature (Af of the distal section 34) is above body temperature, the distal section 34 maintains its malleable properties while inserted into the body and exposed to body temperature. Thus, the distal section 34 of the shaft 14 may be steerable via the steering element 56 and the actuator 26.

[0028] As shown in FIGS. 1 and 2 , the transition section 33 can be disposed between the proximal section 32 and the distal section 34. The transition section 33 can be a portion of the shaft 14 that is exposed to both the heat treatment of the proximal section 32 and the heat treatment of the distal section 34. As a result of such exposure, the transition section 33 can include a distal portion having an Af close to or lower than the second temperature (i.e., the Af of the distal section 34) and a proximal portion having an Af close to or higher than the first temperature (i.e., the Af of the proximal section 32). Thus, the Af of the transition section 33 can vary gradually throughout its length, e.g., gradually increasing between the first and second temperatures, thereby exhibiting a combination of properties when heated to a particular temperature. This variation in Af over the length of the transition section 33 can minimize kinking of the transition section 33 and improve the articulation radius of the transition section 33. However, in other examples, the shaft 14 can lack the transition section 33 and be comprised solely of the proximal section 32 and the distal section 34.

[0029] The distal section 34 may further include cutouts or indentations (e.g., laser cutouts) that may further enhance the maneuverability of the distal section 34. For example, as shown in FIGS. 2 and 3 , the distal section 34 may include an indentation 342 in the body 144 such that the lumen 142 tapers radially inward throughout the indentation 342. The indentation 342 may be a concave cutout (i.e., extending radially inward) around at least a portion (e.g., the entire circumference) of the circumference of the distal section 34, thereby defining a bendable portion 35 having a thinner profile (i.e., a shorter circumference) relative to the remainder of the distal section 34. In some examples, the bendable portion 35 may be, but is not limited to, the portion of the indentation 342 that has the thinnest profile relative to the remainder of the distal section 34. The bendable portion 35 may have a lower stiffness (or higher flexibility) than the rest of the distal section 34. However, the shape and dimensions of the indentation 342 are not particularly limited. The bendable portion 35 may include a constant curvature, as shown in FIGS. 2 and 3 , or may include other shapes, such as varying proximal and distal curvatures. For example, the bendable portion 35 may include a combination of proximal curvature, distal curvature, and flat portions around a portion or the entire circumference of the distal section 34. The method for forming the recesses 342 is also not particularly limited and may be achieved by laser cutting, sawing, grinding, sanding, or the like. The thin outer diameter allows the bendable portion 35 to bend more easily in various directions when the steering elements 56 are manipulated via the actuator 26. As discussed above, the number of different directions in which the bendable portion 35 can articulate may be related to the number of steering elements 56 extending from the actuator 26 and coupled to the distal section 34.

[0030] Heat treating the distal section 34, including the indentations 342, can help improve articulation of the distal section 34 (e.g., increasing the degree of articulation from one side of the section 34 to the other) and improve stress concentration to prevent fracture. Such a process for heat treating the distal section 34 can be more cost-effective than conventional articulating sections, which require multiple steering wires and corresponding lumens. Furthermore, the material stiffness of the flexible distal section of a conventional articulating section is the same as the stiffness of the bulk material in the proximal portion of the flexible section. The flexibility of such devices is achieved through a series of small, mechanically linked / interlocking mechanical elements or through laser-cut patterns that allow the laser-cut portions to bend in multiple directions. In contrast, as discussed above, the distal section 34 can be selectively heat-treated to create malleability in the shape-memory material itself. Furthermore, in some embodiments, thinning the distal section 34 to define indentations, such as indentations 342, can impart additional mechanical flexibility and bending properties / bias.

[0031] 5, an exemplary method 500 of using the medical device 10 will be further described. A user can deliver the distal end of the shaft of the parent scope (e.g., endoscope) into a subject's body, for example, through a natural orifice (such as the mouth or anus). The distal end of the parent scope shaft can be delivered toward a desired target site through the subject's tortuous natural body lumen, such as the esophagus, stomach, or colon, as described in step 501. Next, the user can deliver the shaft 14 (e.g., a guidewire) through a channel or lumen in the parent scope shaft toward or adjacent to the desired target site, as described in step 503. At least a portion of the distal section 34 can extend distally of the parent scope. Once the shaft 14 is delivered into the body, the proximal section 32 can be heated by the subject's body to Af, which can be set to body temperature or a temperature lower than body temperature, causing the proximal section 32 to transform into a superelastic state. Meanwhile, the distal section 34 may have an Af above body temperature, thereby allowing the distal section 34 to maintain its malleable state. The user may then actuate the actuator 26 of the handle 12 to articulate or bend the distal section 34 of the shaft 14, thereby bringing the distal end 38 of the shaft 14 adjacent the intended target site, as described in step 505.

[0032] FIG. 4 illustrates a portion of another exemplary shaft 14' of a medical device 10'. The shaft 14' may have multiple different bending profiles. The distal section 34' of the shaft 14' may include two different cuts or recesses 342', 344' in the body 144', such that the lumen 142' tapers radially inward throughout the recesses in the portion of the distal section 34' that includes the recesses 342', 344'. Each recess 342', 344' may impart a different bending profile to the shaft 14'. However, the number of different cuts or recesses is not particularly limited, and other exemplary shafts may include three, four, five, six, etc. different cuts or recesses to achieve multiple different bending profiles.

[0033] The first recess 342' may be a semicircular cutout (i.e., extending radially inward) concave around a partial circumference of the distal section 34'. The angle at which the first recess 342' extends around or spans the circumference of the distal section 34' is also not particularly limited and may range, for example, from about 20° to about 170°. The first recess 342' results in a first bending profile for the distal section 34'. Given the semicircular cutout of the first recess 342', the first bending profile is a gradual U-shaped curvature around a central point 342'a, which may also be referred to as a "sugarcane" bending profile. Such a bending profile defines a gradual curvature around the central point 342'a, and the shape of the bending profile may resemble a sugarcane, a candy cane, or other similar shapes. The angle of curvature possible around point 342'a depends on the shape and dimensions of the first recess 342'.

[0034] The second recess 344' may be a V-shaped cutout (i.e., extending radially inward) around a partial circumference of the distal section 34, e.g., a portion of the circumference of the distal section 34 that is not bounded by the first recess 342'. The shape and dimensions of the second recess 344' are also not particularly limited. The angle by which the second recess 344' extends around the circumference of the distal section 34' or the circumference of the distal section 34' is also not particularly limited and may be, for example, in the range of about 20° to about 170°. In some examples, the second recess 344' may extend around the distal section 34' to the same extent as the first recess 342'. However, the extent to which the second recess 344' extends around the distal section 34' may also be different from that of the first recess 342'. The second recess 344' results in a second bending profile for the distal section 34'. Considering the V-shaped cut of the second recess 344', the second bending profile of the distal section 34' can bend around a low point 344'a, which may also be referred to as a "hockey stick" bending profile. The second recess 344' can include a proximal portion 344'p and a distal portion 344'd on either side of the low point 344'a. As shown in FIG. 4, the V-shaped cut of the second recess 344' can be asymmetric, such that the angle of the proximal portion 344'p relative to the longitudinal axis of the shaft 14' is different from the angle of the distal portion 344'd relative to the longitudinal axis of the shaft 14'. However, in other examples, the V-shaped cut of the second recess may be symmetrical, such that the angle of the proximal portion 344'p relative to the longitudinal axis of the shaft 14' is the same as the angle of the distal portion 344'd relative to the longitudinal axis of the shaft 14'. The curvature around the low point 344'a may be sharper or steeper than the curvature around the center point 342'a of the first recess 342'. The angle of curvature achievable by the second recess 344' may depend on the shape and dimensions of the second recess 344'.

[0035] The medical device 10' can be used in the same or similar manner as described above for the medical device 10. Further, with reference to FIG. 5 , a user can manually rotate the shaft 14' (e.g., using a handle similar to the handle 12) and pull the steering element 56 to utilize either the first bending profile of the first recess 342' or the second bending profile of the second recess 344' in any orientation. The user can then actuate the actuator 26 of the handle 12 to articulate or bend the distal section 34' about the first recess 342' in the first bending profile, as described in step 507, and / or to articulate or bend the distal section 34' about the second recess 344' in the second bending profile, as described in step 509.

[0036] The guidewires and methods described herein are believed to be applicable to any endoscopic and / or minimally invasive surgical procedure. For example, the systems, devices, and methods described above can be used in percutaneous nephrolithotomy / nephrolithotripsy (PCNL), endoscopic retrograde cholangiopancreatography (ERCP), balloon and laser angioplasty, nephrostomy, electrode placement, etc. The systems, devices, and methods described above can also be used in procedures such as ureteral stone removal, gallstone removal, bile duct stone removal, polyp removal, stent placement, gastrointestinal anastomosis, choledochoduodenal anastomosis, etc. The systems, devices, and methods described above can also be used in intracardiac, coronary, central circulatory, peripheral, and neurovascular procedures.

[0037] While the principles of the present disclosure have been described herein with reference to illustrative examples of particular applications, it should be understood that the disclosure is not limited thereto. Those skilled in the art and with access to the teachings provided herein will recognize additional modifications, applications, embodiments, and equivalent substitutions, all within the scope of the features described herein. Accordingly, the claimed features should not be considered limited by the foregoing description.

Claims

1. A medical device, the medical device comprising: Handle body, and Actuator a handle including: a shaft extending distally from the handle body; the shaft comprises a shape memory material; the shaft includes a proximal section and a distal section, the proximal section having a first austenitic finish temperature and the distal section having a second austenitic finish temperature; The medical device, wherein the first austenite finish temperature is lower than the second austenite finish temperature.

2. 2. The medical device of claim 1, wherein the shaft further comprises a transition section between the proximal section and the distal section, the transition section comprising a proximal portion having an austenite finish temperature close to or higher than the first austenite finish temperature, and the transition section further comprises a distal portion having an austenite finish temperature close to or lower than the second austenite finish temperature.

3. 3. The medical device of claim 1 or 2, wherein the first austenite finish temperature is at or below body temperature and the second austenite finish temperature is above body temperature.

4. The medical device of any one of claims 1 to 3, wherein the distal section comprises at least one depression.

5. The medical device of claim 4 , wherein the at least one depression is a concave cutout, and the at least one depression spans at least a portion of the circumference of the distal section.

6. The medical device of claim 4 or 5, wherein the at least one depression extends around the entire circumference of the distal section.

7. 7. The medical device of claim 4, wherein the distal section includes a bendable portion, the bendable portion being of a smaller circumference than the circumference of the remainder of the distal section, the bendable portion being the part of the distal section having the thinnest profile.

8. The medical device of any one of claims 4 to 7, wherein the distal section comprises a plurality of depressions.

9. The medical device of any one of claims 4 to 8, wherein the distal section includes a first recess and a second recess.

10. 10. The medical device of claim 9, wherein the first depression and the second depression are different shapes and the bending profile of the first depression is different from the bending profile of the second depression.

11. 11. The medical device of claim 9 or 10, wherein the first depression is a concave cutout and the second depression is a V-shaped cutout.

12. The medical device of any one of claims 9 to 11, wherein each of the first and second recesses spans a range of about 20° to about 170° of the circumference of the distal section.

13. The medical device of any one of claims 1 to 12, wherein the at least one depression is laser cut.

14. The medical device of any one of claims 1 to 13, further comprising a plurality of steering elements, each of the plurality of steering elements extending through an interior of the shaft between the actuator and the distal section.

15. 15. The medical device of any one of claims 1 to 14, wherein both the first austenitic finish temperature and the second austenitic finish temperature are set by heat treating the proximal and distal sections of the shaft.

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