Abstract:
An exoskeleton device is capable of being applied to an outer surface of an elongated medical instrument, such as a catheter or a balloon (e.g., an angioplasty balloon, etc.). The exoskeleton device includes a sleeve or another element that is configured to be placed over a distal portion of the elongated medical instrument, one or more features on the sleeve or other element for performing a procedure within the body of a subject, and one or more elements that communicate with the sleeve or other element and/or the features carried thereby to enable performance of the procedure within the body of the subject. Methods of applying exoskeleton devices to elongated medical instruments and methods of using exoskeleton devices are also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    A claim for priority to the Sep. 8, 2015, filing date of U.S. Provisional Patent Application No. 62/215,472, titled EXOSKELETON DEVICES FOR USE WITH ELONGATED MEDICAL INSTRUMENTS (“the &#39;472 Provisional Application”) is hereby made pursuant to 35 U.S.C. §119(e). The entire disclosure of the &#39;472 Provisional Application is hereby incorporated herein. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates generally to exoskeleton devices for use on the outer surfaces of elongated medical instruments, such as catheters and balloons (e.g., angioplasty balloons, etc.). In particular, this disclosure relates to exoskeleton devices, such as devices for engaging or cutting into arterial plaques, infusion devices, electronic devices, shaping devices, etc., with tethers or other manipulation (e.g., removal, movement, etc.) features. This disclosure also relates to exoskeleton devices that include elongated elements on a body, or carrier, that may be applied to an elongated medical instrument, such as a catheter or an angioplasty balloon. 
       SUMMARY 
       [0003]    In various aspects, this disclosure relates to exoskeleton devices that are configured to be disposed on elongated medical instruments, such as catheters or balloons (e.g., angioplasty balloons, etc.). Embodiments of exoskeleton devices that are configured for use with expandable elements of elongated medical instruments (e.g., balloons, such as angioplasty balloons; etc.) may also be configured to expand and resiliently contract when the expandable elements are respectively inflated and deflated. In addition to exoskeleton devices, assemblies that include an exoskeleton device and an elongated medical instrument (e.g., a catheter, a balloon, etc.) are disclosed, as are methods for using exoskeleton devices. 
         [0004]    In one aspect, an exoskeleton device according to this disclosure may comprise a body, or a carrier, that is configured to be positioned over an elongated medical instrument, such as a catheter or an angioplasty balloon. The body may be defined by a single tubular element or by a plurality of elements. In addition, the body of an exoskeleton device configured for use with an expandable portion of an elongated medical instrument may, when the portion of the elongated medical instrument it surrounds expands radially (e.g., is inflated, etc.), also be configured to expand. The body of such an exoskeleton device may also be configured to resiliently return to its unexpanded configuration when the portion of the elongated medical instrument it surrounds contracts (e.g., is deflated, etc.). The body of an exoskeleton device according to this disclosure may also be configured to be used with elongated medical instruments of a plurality of different diameters. 
         [0005]    In various embodiments, the body of an exoskeleton device may comprise a sleeve that is configured to completely surround the circumference of at least a portion the length of an elongated medical instrument. A body with such a configuration may comprise an elongated tubular element, or a sleeve. The dimensions of the body, as well as the material from which it is made, may enable it to be positioned on an unexpanded portion of an elongated medical instrument and to remain on the unexpanded portion of the elongated medical instrument while that portion remains in an unexpanded (e.g., uninflated) state. Of course, in embodiments where the exoskeleton device is introduced onto an expandable portion of an elongated medical instrument, expansion of the expandable portion may cause the elongated medical instrument to further engage (or to be engaged by) the exoskeleton device. 
         [0006]    In some embodiments, the body of an exoskeleton device may be configured to be circumferentially rolled upon itself, which may impart the carrier with the appearance of a ring. A body embodied in such a manner may be oriented adjacent to an end of an elongated medical instrument (e.g., a catheter or a balloon (e.g., an uninflated angioplasty balloon, etc.) prior to its introduction into the body of a subject, and then unrolled onto the elongated medical instrument, which may also occur prior to their introduction into the subject&#39;s body or while the elongated medical instrument and the exoskeleton device are being introduced into the subject&#39;s body. 
         [0007]    As an alternative to including a single elongated tubular element, a body of an exoskeleton device according to this disclosure may comprise a plurality of collars that are configured to circumferentially surround and engage locations along the length of an elongated medical instrument, as well as one or more elongated elements that extend from one collar to another and, thus, that are configured to extend along at least a portion of a length of the elongated medical instrument. In embodiments where an exoskeleton device includes a plurality of elongated elements, the elongated elements may be configured for positioning at different radial positions around a surface of the elongated medical instrument. Together, the collars and the elongated element(s) define a cage for receiving at least a portion of the length of the elongated medical instrument. 
         [0008]    The body of an exoskeleton device according to this disclosure may carry or comprise (e.g., ribs of a tubular embodiment, the elongated elements of a cage embodiment, etc.) exterior elements, which are configured to perform one or more specific functions when the exoskeleton device and the elongated medical instrument by which it is carried are introduced into the interior of a subject&#39;s body. 
         [0009]    In a specific embodiment, the exterior elements may comprise small blades, which are known as “atherotomes.” Such an exterior element may also be referred to herein as a “cutting element.” An atherotome may include one or more edges. Exterior elements with atherotomes may, for example, be configured to cut into, score or otherwise engage a plaque into which they are forced (e.g., by inflation of the portion of the elongated medical instrument (e.g., the catheter, the angioplasty balloon, etc.) over which the atherotomes are positioned, etc.). 
         [0010]    In embodiments where an atherotome resides on a catheter, the catheter may be forced against the plaque in such a way that the atherotome engages, scores and/or cuts into the plaque. In embodiments where the exoskeleton device resides on an angioplasty balloon, the atherotome may engage, score and/or cut into the plaque as the angioplasty balloon is expanded by inflating the angioplasty balloon. 
         [0011]    In some embodiments, an atherotome may comprise a polymer that expands when placed under a load and that resiliently contracts when the load is released. More specifically, a width of the atherotome may expand when the atherotome is placed under tensile stress and resiliently contract when the tensile stress is released. Such a polymeric atherotome may include an edge that is more pronounced when little or no load is applied in a direction transverse to a length of the exterior element and that becomes less pronounced and, thus, loses some of its ability to cut into, score or otherwise engage the arterial plaque as more of a tensile load is applied to its opposite sides (e.g., as an angioplasty balloon on which the atherotome resides is inflated, etc.). 
         [0012]    Alternatively, an exterior element that comprises an athertome may be associated with the body of an exoskeleton device or, in embodiments where the external element comprises a part of the body, it may be associated with other elements of the body of the exoskeleton device in such a way that an orientation of the edge(s) of the atherotome changes as the body circumferentially extends or contracts. As an example, when the body is in a relaxed state, edge(s) of the exterior element may be oriented radially or substantially radially relative to a longitudinal axis of the exterior element. As the body circumferentially expands, the angle(s) at which the edge(s) of the exterior element is (are) oriented may become more tangential, thereby reducing the likelihood that the edge(s) will score, cut into or otherwise engage an arterial plaque. 
         [0013]    Whether or not they comprise atherotomes, the exterior elements of an exoskeleton device according to this disclosure may include one or more conduits. An exterior element with a conduit extending therethrough may be configured to expel fluid, or cause fluid to be infused into the body of a subject, or to obtain a sample from the body of the subject. Some embodiments of exterior elements that include conduits (e.g., hypotubes, elongated tubular polymer elements, etc.) may include one or more small openings, which are referred to herein as “pores,” that extend through a wall of the exterior element and that are positioned at an intermediate location along the length of the exterior element to enable fluid to flow from the conduits to the outer surface of the exterior element. Embodiments of exterior elements that include a plurality of pores may enable fluid delivery to a plurality of locations that are spread over a wide area. An exterior element that has a conduit may have an open distal end or one or more larger openings that extend through the wall of the exterior element to enable the delivery of fluid to a selected location within the body of a subject or the withdrawal of fluid from a selected location within the body of a subject. 
         [0014]    Alternatively, the exterior elements of an exoskeleton device may comprise electrically conductive elements, such as circuit traces and electrodes. Electrically conductive elements may perform a variety of functions, including, without limitation, the delivery of heat to one or more desired locations within a subject&#39;s body and/or the delivery of electricity to one or more desired locations within a subject&#39;s body. Electrically conductive elements may also enable the communication of electrical signals to and/or from devices that are carried by an elongated medical instrument and by the body of an exoskeleton device to one or more desired locations within a subject&#39;s body (e.g., sensors, etc.). 
         [0015]    Exterior elements that provide other types of functionality are also within the scope of this disclosure. 
         [0016]    Some embodiments of exterior elements may be deformable, and configured to hold a shape into which they are formed, which may enable an exoskeleton device to define a shape of a portion of an elongated medical instrument (e.g., a catheter, an angioplasty balloon, etc.) on which the exoskeleton device resides. 
         [0017]    An exoskeleton device according to this disclosure may optionally include a tether, which may extend proximally from the body of the exoskeleton device. The tether of an exoskeleton device may extend longitudinally (or at least somewhat longitudinally) from the body of the exoskeleton device. When the body of the exoskeleton device resides on an elongated medical instrument (e.g., a catheter. an angioplasty balloon, etc.) within the body of a subject, the exoskeleton device may extend in a proximal direction, to a location outside of the subject&#39;s body. Thus, the tether may have a length that exceeds the length of an elongated medical instrument with which the tether is used. Such a tether may be configured to ensure that the exoskeleton device can be removed from a subject&#39;s body, for example, when the catheter or the angioplasty balloon with which the exoskeleton device is associated is removed from the subject&#39;s body. In some embodiments, including those where one or more of the exterior elements of an exoskeleton device include conduits and pores or other openings, a tether may also include a conduit extending along its length. That conduit may communicate with the conduit of at least one exterior element, which enables fluid introduced into conduit of the tether to flow into the conduit of the at least one exterior element, to be communicated through the pores in the at least one exterior element, and to be introduced into a location where the at least one exterior element resides (e.g., into a blood vessel, into the presence of plaque within a blood vessel, etc.). In embodiments where electrical signals are to be conveyed to and/or from circuitry on an exoskeleton device, the tether may include or carry one or more wires. 
         [0018]    In some embodiments, the tether may comprise a single elongated element, such as a wire, hypotube, elongated polymer element or the like. In other embodiments, an exoskeleton device may include two or more tethers. In embodiments that include a plurality of tethers, the tethers may remain separate from one another, or they may be secured together (e.g., by welding or bonding, by twisting, by braiding, etc.) along at least a portion of their lengths. 
         [0019]    According to another aspect, methods for extending the functionality of an elongated medical instrument, such as a catheter or a balloon (e.g., an angioplasty balloon, etc.) are disclosed. Such a method may include installing an exoskeleton device onto an exterior of the elongated medical instrument (e.g., onto an exterior of a distal portion of the elongated medical instrument, etc.). With the exoskeleton device in place, the elongated medical instrument (e.g., its distal portion, etc.) may be introduced into a body of a subject. The elongated medical instrument (e.g., its distal portion, etc.) and the exoskeleton device carried thereby may then be advanced to a desired location with the subject&#39;s body. With the elongated medical instrument (e.g., its distal portion, etc.) and the exoskeleton device in place, one or both of them may be used to perform a procedure at the desired location within the subject&#39;s body. Thereafter, the elongated medical instrument and the exoskeleton device may be removed from the subject&#39;s body. 
         [0020]    Other aspects, as well as features and advantages of various aspects, of the disclosed subject matter will become apparent to those of ordinary skill in the art through consideration of the ensuing description, the accompanying drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    In the drawings: 
           [0022]      FIGS. 1, 2 and 3  illustrate various embodiments of exoskeleton devices, with each exoskeleton device including a body, or a carrier or cage, configured to surround an elongated medical instrument (e.g., a catheter, an angioplasty balloon, etc.), the body of the exoskeleton device being defined by a plurality of elongated external elements configured to be oriented along a length of the elongated medical instrument; 
           [0023]      FIGS. 1A, 2A and 3A  show the embodiments of exoskeleton devices of  FIGS. 1, 2 and 3 , respectively, installed on elongated medical instruments; 
           [0024]      FIGS. 1B and 3B  depict the elongated medical instruments of  FIGS. 1A and 3A , respectively—angioplasty balloons in the depicted embodiments—in expanded (e.g., inflated, etc.) states and the bodies of the exoskeleton devices of  FIGS. 1 and 1A  and of  FIGS. 3 and 3A , respectively, in expanded states; 
           [0025]      FIGS. 4A, 4B and 4C  illustrate an embodiment of a body of an exoskeleton device that is in maintained in a rolled configuration before it is installed on an elongated medical instrument, as well as an embodiment of installation of the exoskeleton device onto an elongated medical instrument, which includes unrolling the body onto the elongated medical instrument in a proximal direction; 
           [0026]      FIGS. 5A, 5B and 5C  show an embodiment of a body of an exoskeleton device that is maintained in a dual rolled configuration before it is installed on an elongated medical instrument, as well as an embodiment of installation of the exoskeleton device onto an elongated medical instrument, which includes unrolling a distal side of the body in a distal direction and unrolling a proximal side of the body in a proximal direction; 
           [0027]      FIGS. 6A, 6B and 6C  depict another embodiment of a body of an exoskeleton device that is maintained in a rolled configuration before it is installed on an elongated medical instrument, as well as an embodiment of installation of the exoskeleton device onto an elongated medical instrument, which includes unrolling the body in a distal direction; 
           [0028]      FIGS. 7A and 7B  show an embodiment of an exoskeleton device with external elements that are configured to enable fluids to be conveyed through the exoskeleton device to one or more locations within a subject&#39;s body and/or from one or more locations within the subject&#39;s body; and 
           [0029]      FIG. 8  depicts an embodiment of exoskeleton device with a body that is configured to hold and deliver a substance (e.g., a therapeutic agent in a liquid state or a solid state, a medicament in a liquid state or a solid state, etc.) to a desired location within a body of a subject. 
       
    
    
       [0030]    Similar reference characters in different drawings may refer to similar elements, which may, in some embodiments, include features, functions and/or other characteristics that are the same as or similar to one another. 
       DETAILED DESCRIPTION 
       [0031]    With reference to  FIGS. 1-1B , an embodiment of an exoskeleton device  10  that is configured to be positioned over an angioplasty balloon  40  ( FIG. 1A ) is depicted. The exoskeleton device  10  includes a body  20  and a tether  30 . 
         [0032]    The body  20  of the exoskeleton device  10  is defined by at least two collars—the distal collar  24  and the proximal collar  26  illustrated by  FIGS. 1-1B —that are configured to be placed at different positions along the length of an elongated medical instrument  40  ( FIGS. 1A and 1B ), such as a catheter or a balloon (e.g., an angioplasty balloon, etc.), as well as one or more external elements  22  (a plurality of external elements  22  are shown in  FIGS. 1-1B ) that extend from the proximal collar  26  to the distal collar  24 . The distal collar  24  and the proximal collar  26  may be configured to engage (e.g., resiliently, by interference fit, etc.) the elongated medical instrument  40  in a manner that holds the body  20  of the exoskeleton device  10  in place at a desired location along a length of the elongated medical instrument  40 . 
         [0033]    As depicted, the external elements  22  are elongate members that are oriented substantially parallel to one another. The external elements  22  may be arranged in such a way as to define an outer periphery of a receptacle (e.g., in a somewhat cylindrical fashion, etc.), such as a cage, for receiving an elongated medical instrument  40 , such as a catheter or a balloon (e.g., an angioplasty balloon, etc.) ( FIGS. 1A and 1B ). While  FIGS. 1-1B  illustrate each external element  22  as being a substantially linear member that is oriented parallel to a length of the body  20 , other orientations are also within the scope of this disclosure, including, without limitation, helically oriented external elements  22 , external elements  22  with multiple curve (e.g., sigmoidal, or S, shapes, etc.), etc. 
         [0034]    The distal collar  24  may be located at a distal end  20   d  of the body  20  of the exoskeleton device  10  and, in embodiments where the body  20  includes a plurality of external elements  22 , may secure distal ends  22   d  of the external elements  22  in place relative to one another. The distal collar  24  may be configured to receive a distal end of an elongated medical instrument  40  and, thus, to hold the body  20 , as well as the remainder of the exoskeleton device  10  in place on a distal portion  41  of the elongated medical instrument  40 . In the depicted embodiment, with the exoskeleton device  10  in place on the distal portion  41  of the elongated medical instrument  40 , a more proximal portion  42  of the elongated medical instrument  40  remains exposed. 
         [0035]    The proximal collar  26  of the body  20  of the exoskeleton device  10  may be located at a proximal end  20   p  of the body  20 . In embodiments where the body  20  includes a plurality of external elements  22 , the proximal collar  26  may secure proximal ends  22   p  of the external elements  22  in place relative to one another. The proximal collar  26  may be configured to be positioned over, and to receive, a somewhat proximal portion of the elongated medical instrument  40 . In the embodiment illustrated by  FIGS. 1-1B , the proximal collar  26  be positioned proximally adjacent to a proximal side of the distal portion  41  (e.g., an expandable element, etc.) of the elongated medical instrument  40 . The proximal collar  26  may be configured to engage the portion of the elongated medical instrument  40  over which it is positioned and, thus, may hold the body  20  and the remainder of the exoskeleton device  10  in place on the distal portion  41  of the elongated medical instrument  40 . As illustrated by  FIG. 1B , the proximal collar  26 , when positioned on the proximal side of an expandable distal portion  41  of an elongated medical instrument  40 , may be configured to function in conjunction with the distal collar  24  to hold the body  20  in place over the distal portion  41 , such as when the distal portion  41  is at least partially inflated, and may enable the body  20  of the exoskeleton device  10  to accommodate expansion of the distal portion  41 . 
         [0036]    In addition to a body  20 , an exoskeleton device  10  according to this disclosure may include a tether  30 . The tether  30  may be configured to enable an individual, such as a healthcare provider, to maintain control over the exoskeleton device  10  from a location outside of a subject&#39;s body while the exoskeleton device  10  and a distal portion  41  of an elongated medical instrument  40  on which the exoskeleton device  10  has been positioned remain within the subject&#39;s body. As an example, a tether  30  may enable an individual to remove the exoskeleton device  10  in the event that it becomes dislodged from the distal portion  41  of the elongated medical instrument  40 . As another example, a tether  30  may facilitate removal of an elongated medical instrument  40  from a subject&#39;s body; for example, the tether  30  may be pulled with a proximal portion  42  of the elongated medical instrument  40  to reinforce or supplement a pulling force applied to the proximal portion  42 . In some embodiments, a tether  30  may provide further functionality. As a few non-limiting examples, a tether  30  may enable manipulation of the exoskeleton device  110  once it has been introduced into a subject&#39;s body, the communication of liquids into and/or out of the subject&#39;s body, and/or the communication of electrical signals between the exoskeleton device  110  within the subject&#39;s body and one or more apparatuses outside of the subject&#39;s body. 
         [0037]    In some embodiments, the tether  30  may comprise a single elongated element with a distal end that is secured to a proximal end of the body  20 . In other embodiments, the tether  30  may comprise a proximal extension of one or more external elements  22  of the body  20  of the exoskeleton device  10 . 
         [0038]    Turning now to  FIGS. 2 and 2A , an embodiment of exoskeleton device  10 ′ is illustrated that includes a body  20 ′ that resembles the body  20  of the embodiment of exoskeleton device  10  depicted by  FIGS. 1-1B , but differs from the exoskeleton device  10  in a number of respects. 
         [0039]    As one example, the exoskeleton device  10 ′ shown in  FIGS. 2 and 2A  includes a tether  30 ′ formed by proximal extensions of at least two external elements  22 ′. Thus, the tether  30 ′ includes more than one element, or it could be said that the exoskeleton device  10 ′ includes more than one tether  30 ′. 
         [0040]    As another example, the body  20 ′ of an exoskeleton device  10 ′ may include a proximal collar  26 ′ that holds intermediate portions  22   i ′ of external elements  22 ′ in place relative to one another to define a proximal end  20   p ′ of the body  20 ′, with or without holding the body  20  in place relative to a proximal side of the distal portion  41 ′ of an elongated medical instrument  40 ′ ( FIG. 2A ). 
         [0041]    As another option, a proximal collar  26 ′ of the body  20 ′ of an exoskeleton device  10 ′ may be configured to slide along the lengths of the external elements  22 ′ in a manner that enables the body  20 ′ to accommodate and receive a distal portion  41  of an elongated medical instrument  40  ( FIG. 2A ). Such a proximal collar  26 ′ may also be configured to lock into place at a desired location along the lengths of the external elements  22 ′ to enable the proximal collar  26 ′ to impart the body  20 ′ with a length that corresponds to the length of the distal portion  41  and to engage a proximal end of the distal portion  41 , thereby securing the body  20 ′ in place over the distal portion  41  of the elongated medical instrument  40 . 
         [0042]    An exoskeleton device  10 ′ may also include one or more positioning collars  28 ′ that are located proximal to the body  20 ′. Each positioning collar  28 ′ may hold the elements of a tether  30 ′ in place relative to one another and/or hold a tether  30 ′ in place relative to another feature, such as a proximal portion  42  of the elongated medical instrument  40 . 
         [0043]      FIGS. 3-3B  depict another embodiment of exoskeleton device  10 ″, in which each external element  22 ″ includes a distal portion  22   d ″ and a proximal portion  22   p ″. The distal portion  22   d ″ of each external element  22 ″ may be configured to be positioned over a distal portion  41  of an elongated medical instrument  40  with which the exoskeleton device  10 ″ is configured to be used. The proximal portion  22   p ″ of each external element  22 ″ may be configured to extend proximally to a location near, at or beyond a proximal end (not shown) of the elongated medical instrument  40 . Thus, the proximal portion  22   p ″ of each external element  22 ″ may act as a tether  30 ″, or proximal portions  22   p ″ of a plurality of external elements  22 ″ may collectively function as a tether  30 ″. While the exoskeleton device  10 ″ shown in  FIGS. 3-3B  includes a distal collar  24 ″, which may secure the exoskeleton device  10 ″ and its external elements  22 ″ in place at or near a distal end of the elongated medical instrument  40 ″, the exoskeleton device  10 ″ may lack a proximal collar  26 . 
         [0044]    Turning now to  FIGS. 4A-6C , various embodiments of another type of exoskeleton device are illustrated. 
         [0045]      FIGS. 4A-4C  show an embodiment of exoskeleton device  110  that is initially provided to a healthcare provider in a rolled configuration, as shown in  FIG. 4A . In the rolled configuration, a body  120  of the exoskeleton device  110  (which may have a tubular configuration when unrolled (see, e.g.,  FIG. 4C )) may be circumferentially or axially rolled upon itself. While in the rolled configuration, the exoskeleton device  110  may resemble a ring with an aperture, or a lumen  111 , through its center. In some embodiments, an introduction element  115 , which be annular or tubular in shape and may be somewhat rigid (e.g., relative to the exoskeleton device  110  while in its rolled configuration, etc.), may be aligned with and disposed in the lumen  111 . The introduction element  115  may include a lumen  116  with an inner diameter that is larger than an outer diameter or a portion of an elongated medical instrument  40  onto which the exoskeleton device  110 , in its rolled configuration, is to be installed. 
         [0046]    While in its rolled configuration, the exoskeleton device  110  is oriented relative to an elongated medical instrument  40 . More specifically, the exoskeleton device  110  may be oriented such that it can be unrolled onto the elongated medical instrument  40  in a proximal direction. With the exoskeleton device  110  properly oriented, it may be positioned over a distal end  40   d  of the elongated medical instrument  40  and onto the elongated medical instrument  40  at a location distally adjacent to distal side of a distal portion  41  of the elongated medical instrument  40  or at the distal side of the distal portion  41 . Stated another way, the distal end  40   d  of the elongated medical instrument  40  may be inserted into and, optionally, at least partially through a lumen  111  of the exoskeleton device  110  while the exoskeleton device  110  remains in its rolled configuration. In embodiments where the exoskeleton device  110  is rolled onto an introduction element  115 , introduction of the distal end  40   d  of the elongated medical instrument  40  may be inserted into and, optionally, at least partially through the lumen  111  of the exoskeleton device  110  may include introducing the distal end  40   d  into and, optionally, at least partially through the lumen of the introduction element  115 . 
         [0047]    As illustrated by  FIG. 4B , once the exoskeleton device  110 , in its rolled configuration, has been properly positioned on the elongated medical instrument  40 , it may be unrolled in a proximal direction onto the distal portion  41  of the elongated medical instrument  40 . In embodiments where the exoskeleton device  110  was rolled onto an introduction element  115 , the introduction element  115  may remain in place, or it may be removed from between the exoskeleton device  110  and the elongated medical instrument  40 . 
         [0048]      FIG. 4C  shows the exoskeleton device  110  in an installed configuration. A body  120  of the exoskeleton device  110 , which may comprise an elastic material, may engage an outer surface of the distal portion  41  of the elongated medical instrument  40  as the exoskeleton device  110  and, more specifically, its body  120  are unrolled onto the distal portion  41 . Depending on the extent to which the body  120  engages the distal portion  110 , some embodiments of the exoskeleton device  110  may lack a tether. The embodiment of exoskeleton device  110  illustrated by  FIGS. 4A-4C  may, however, include a tether  130 , which may enable manipulation of the exoskeleton device  110  once it has been introduced into a subject&#39;s body, the communication of electrical signals between the exoskeleton device  110  within the subject&#39;s body and one or more apparatuses outside of the subject&#39;s body, and/or the communication of liquids into and/or out of the subject&#39;s body. 
         [0049]    In addition to the body  120  and an optional tether  130 , an exoskeleton device  110  may include one or more exterior elements  122 . Each exterior element  122  may comprise an element that has been secured to an exterior surface of the body  120 , an element that has been at least partially embedded within the body  120  or an element that has been defined in the body  120  (e.g., by processes, such as extrusion, molding, etc., used to make the body  120 ; etc.). Any exterior element(s)  122  and/or tether  130  may be rolled with the body  120  of the exoskeleton device  110  when the exoskeleton device  110  is in its rolled configuration, and may unroll with the body  120  as the exoskeleton device  110  is installed on a distal portion  41  of an elongated medical instrument  40 . 
         [0050]    Looking now to  FIGS. 5A-5C , another embodiment of exoskeleton device  110 ′ is depicted. In its initial configuration (i.e., the configuration in which the exoskeleton device  110 ′ is provided to a healthcare professional), which is shown in  FIG. 5A , both ends of the exoskeleton device  110 ′ are rolled toward a center of the length of the exoskeleton device  110 ′, imparting the exoskeleton device  110 ′ with the dual rolled configuration shown in  FIG. 5A . An introduction element  115 ′, which may be configured in the same manner as or in a similar manner to the introduction element  115  shown in  FIG. 4A , may extend through a lumen  111 ′ of the dual rolled configuration of the exoskeleton device  110 ′, may facilitate its introduction onto an elongated medical instrument  40 . 
         [0051]    After the exoskeleton device  110 ′, in its rolled configuration, has been properly positioned on the elongated medical instrument  40 , its two sides, or rolls, may be unrolled onto the distal portion  41  of the elongated medical instrument  40  in their respective proximal and distal directions. The introduction element  115 ′, if any, may remain in place, or it may be removed after one side of the exoskeleton device  110 ′ has been at least partially unrolled, but while the other side of the exoskeleton device  110 ′ remains rolled (i.e., while the introduction element  115 ′ is still accessible). 
         [0052]      FIG. 5C  shows the exoskeleton device  110 ′ in an installed configuration, in which its elongated body  120 ′, one or more optional external elements  122 ′ and an optional tether  130 ′ can be seen, each of which may be configured in the same manner as or in a similar manner to the corresponding elements described in reference to  FIGS. 4A-4C . 
         [0053]      FIGS. 6A-6C  illustrate an embodiment of exoskeleton device  110 ″ having a configuration similar to that of the embodiment of exoskeleton device  110  shown in  FIGS. 4A-4C , but rolled from a direction that facilitates unrolling in a distal direction (as shown in  FIG. 6B ). As such, as illustrated by  FIGS. 6A and 6B , proximal portions of any external elements  122 ″ and a tether  130 ″, if any, may extend from a proximal side of the rolled configuration of the exoskeleton device  110 ″ without having been rolled up themselves. 
         [0054]    In various embodiments, the body of an exoskeleton device, or at least a portion of the body, may comprise a material that shrinks when exposed to certain conditions (e.g., an elevated temperature, etc.). The body of such an exoskeleton device may be introduced onto an elongated medical instrument at a desired location, and then shrunk to a size that enables the body of the exoskeleton device to engage the elongated medical instrument. 
         [0055]    With reference turned to  FIGS. 1, 7A, 7B and 8 , a variety of optional functions that may be performed by the external elements  22  (or external elements  22 ′,  22 ″,  122 ,  122 ′,  122 ″— FIGS. 2, 3, 4A, 5A and 6A , respectively) of an exoskeleton device  10 ,  10 ′,  10 ″,  110 ,  110 ′,  110 ″ ( FIGS. 1, 2, 3, 4A, 5A and 6A , respectively) will now be described. 
         [0056]    With reference to  FIG. 1 , various embodiments of exterior elements  22  include, but are not limited to, wires, elongated polymeric elements (which may expand when placed under a load and resiliently contract when the load is released; more specifically, a width of a polymeric element may expand when placed under tensile stress and resiliently contract when the tensile stress is released) and hypotubes. In some embodiments, the exterior elements  22  may include edges that enable them to engage an adjacent object, such as an arterial plaque. Such an edge may comprise blade, or atherotome, which may enable the external elements  22  to score or cut into an adjacent object. 
         [0057]    As inferred by the potential use of hypotubes to define external elements  22 , an external element  22  may, as another option, include a conduit (not shown) extending along its length. As an alternative to the use of a hypotube, an elongated polymeric element may include a conduit. An external element  22  with a conduit may be configured to convey, or communicate, fluid from one location to another (e.g., from a location outside of a subject&#39;s body to the location of the external element  22 , etc.). Thus, an external element  22  that includes a conduit may also include one or more pores  23   p  or other openings along its length, as illustrated by  FIGS. 7A  and  7 B. In addition, or as an alternative, a distal end of the conduit may terminate at an opening  23   o , which may be located along the length of an external element  22  or at a distal end  22   d  of the external element  22 . In embodiments where the conduit and its associated pores  23   p  and/or opening(s)  23   o  communicate liquid to a desired location within a subject&#39;s body, the liquid may be forced from an external source  50  into the conduit and out of the pores  23   p  and/or opening(s)  23   o . In embodiments where the pores  23   p  and/or opening(s)  23   o  are used to obtain a sample from a subject&#39;s body, a collection element  50  located outside of the subject&#39;s body may create or be associated with a vacuum source to apply a vacuum to the conduit and its associated pores  23   p  and/or opening(s)  23   o.    
         [0058]    As another option, and with continued reference to  FIGS. 7A and 7B , one or more of the external elements  22  may comprise wires. The wires may comprise standalone electrically conductive wires or substrate (e.g., a flexible substrate, a circuit board, etc.) that carries one or more electrically conductive elements. In embodiments where one or more external elements  22  comprise such circuitry, the circuitry may be configured to convey electricity with minimal resistance, it may comprise one or more electrically resistive (i.e., heating) elements. In embodiments where an external element  22  comprises circuitry, the circuitry may communicate with an electronic device  50  located outside of a subject&#39;s body and, in some embodiments, with one or more electronic components  23   p  (e.g., electrodes, sensors, thermistors, etc.) carried by the exoskeleton device  10 . 
         [0059]    An external element  22  that comprises a wire or a similar structure may be configured to shape an elongated medical instrument  40  on which the exoskeleton device  10  of which the external element  22  is a part is disposed. In such an embodiment, the external element  22  may be configured to hold a shape into which it is formed (e.g., it may be malleable, etc.); Alternatively, the external element  22  may be flexible under certain conditions (e.g., at room temperature, etc.) and more rigidly hold a desired shape under other conditions (e.g., at body temperature) (e.g., it may comprise a shape memory alloy, such as a nitinol (Nickel Titanium Naval Ordinance Laboratory) material; etc.). Such an embodiment of external element  22  may enable a healthcare professional to impart a flexible elongated medical instrument  40  (e.g., a catheter, etc.) with a desired shape when the elongated medical instrument  40  is introduced into a subject&#39;s body or after the elongated medical instrument  40  has been introduced into the subject&#39;s body. 
         [0060]      FIG. 8  illustrates an embodiment of an exoskeleton device  210  with a body  220  that may carry a substance  221  that is to be delivered to a location within a subject&#39;s body. The body  220  of the exoskeleton device  210  may comprise a matrix that carries the substance  221  that is to be delivered into the subject&#39;s body. In a specific embodiment, the body  220  may have an open celled porous structure, which may impart it with sponge-like characteristics. The matrix of the body  220  may be formed from any of a variety of suitable materials, including, without limitation, polyethylene, latex, etc. In some embodiments, the body  220  may include an absorbent material, such as a hydrogel or the like. 
         [0061]    The substance  221  absorbed by the body  220  of the exoskeleton device  210  may comprise a therapeutic agent, medicament, a dye or any other substance a healthcare professional may want to introduce into a subject&#39;s body, and it may be in a solid form or a liquid form. The substance  221  may be integrated into the matrix of the body  220  of the exoskeleton device  210  as the body  220  is formed, after the body  220  is formed but before it is packaged or by the healthcare professional. Alternatively, the substance  221  may be added directly to the body  220  of the exoskeleton device  210  by a healthcare professional. As another option, the substance  221  may be introduced into the body  220  of the exoskeleton device  210  through a tether  230  that communicates with the body  220  (e.g., from a location outside the subject&#39;s body while the exoskeleton device  210  resides within the subject&#39;s body, etc.). 
         [0062]    An exoskeleton device  210  of the type described in reference to  FIG. 8  may be configured to obtain a sample from a location within a body of a subject. When the exoskeleton device  210  is positioned at a desired location within a subject&#39;s body, the body  220  of such an exoskeleton device  210  may absorb a liquid or a fluid, or to receive another material from within the subject&#39;s body. 
         [0063]    In an embodiment of use of an exoskeleton device, reference is returned to  FIGS. 3-3B  of the drawings. As illustrated by  FIG. 3 , an exoskeleton device  10 ″ may be provided. The exoskeleton device  10 ″ may be installed onto an appropriate location of an elongated medical instrument  40  (e.g., onto an exterior of the elongated medical instrument  40 , etc.), as shown in  FIG. 3A . As depicted, the exoskeleton device  10 ″ may be installed on a distal portion  41  of an elongated medical instrument  40 . In the specific embodiment depicted by  FIG. 3A , the exoskeleton device  10 ″ may be installed over an angioplasty balloon of an angioplasty device. 
         [0064]    With the exoskeleton device  10 ″ in place upon the elongated medical instrument  40 , the elongated medical instrument  40  and the exoskeleton device  10 ″ may be introduced into a body of a subject, and introduced to a desired location within the subject&#39;s body. In embodiments where the elongated medical instrument  40  comprises an angioplasty device, the angioplasty balloon of such a device and the exoskeleton device  10 ″ carried thereby may be introduced into a blood vessel and advanced to a location where a plaque at least partially blocks the flow of blood through the blood vessel. 
         [0065]    With the elongated medical instrument  40  and the exoskeleton device  10 ″ properly positioned within the subject&#39;s body, one or both of the exoskeleton device  10 ″ and the elongated medical instrument  40  may be used to perform a procedure at the desired location. Continuing with the embodiment where the elongated medical instrument  40  is an angioplasty device and its distal portion  41  comprises an angioplasty balloon, the angioplasty balloon of the angioplasty device may be inflated. Inflation of the angioplasty balloon may cause external elements  22 ″ of the exoskeleton device  10 ″ to contact the plaque, and even to engage the plaque. In embodiments where the external elements  22 ″ comprise blades, the external elements  22 ″ may cut into the plaque. 
         [0066]    With the exoskeleton device  10 ″ and its external elements  22 ″, if any, in place, the exoskeleton device  10 ″ may be used to perform a procedure at the desired location. As a non-limiting example, in embodiments where the elongated medical instrument and the exoskeleton device  10 ″ are used to perform angioplasty, a tether  30 ″ of the exoskeleton device  10 ″ may be manipulated to cause the external elements  22 ″ to cut into the plaque. As another example, the exoskeleton device  10 ″ may be used to deliver a substance to the desired location, to obtain a sample from the desired location, to heat the desired location, to sense a particular condition (e.g., a temperature, etc.) at the desired location or to perform any of a variety of other functions at the desired location. 
         [0067]    Once the desired procedure has been performed, the elongated medical instrument  40  and the exoskeleton device  10 ″ may be removed from the subject&#39;s body. 
         [0068]    Although the preceding disclosure provides many specifics, these should not be construed as limiting the scope of any of the ensuing claims. Other embodiments may be devised which do not depart from the scopes of the claims. Features from different embodiments may be employed in combination. The scope of each claim is, therefore, indicated and limited only by its plain language and the full scope of available legal equivalents to its elements.