Patent Publication Number: US-2016228126-A1

Title: Occlusion device

Description:
RELATED APPLICATION 
     This application claims priority to, and the benefit of, U.S. Patent Application No. 62/113,111, filed on Feb. 6, 2015, which is incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to endovascular devices, and more particularly, to vaso-occlusive devices for the occlusion of body lumens and cavities. 
     BACKGROUND 
     In many clinical situations, blood vessels are occluded for a variety of purposes, such as to control bleeding, to prevent blood supply to tumors, and to block blood flow within an aneurysm. Vaso-occlusive devices have been used in the treatment of aneurysms. Vaso-occlusive devices are surgical implants placed within blood vessels or vascular cavities, typically by the use of a catheter, to form a thrombus and occlude the site. For instance, an aneurysm may be treated by introduction of a vaso-occlusive device through the neck of the aneurysm. The thrombogenic properties of the vaso-occlusive device cause a mass to form in the aneurysm and alleviate the potential for growth of the aneurysm and its subsequent rupture. Other diseases, such as tumors, may also be treated by occluding the blood flow to a target area. 
     SUMMARY 
     This disclosure relates to endovascular devices, and more particularly, to vaso-occlusive devices for the occlusion of body lumens and cavities. In one illustrative embodiment, a medical device can include a catheter shaft extending from a proximal end to a distal end. The catheter shaft may further include a plurality of lumens extending through at least a portion of the catheter shaft. In some embodiments, a balloon member may be disposed proximate the distal end of the catheter shaft. The catheter shaft may further comprise a frangible portion disposed proximate the distal end of the catheter shaft for detaching the balloon member from the catheter shaft. 
     Alternatively, or additionally, the catheter shaft may have a first wall thickness proximal of the frangible portion, the frangible portion may have a second wall thickness, and the second wall thickness may be less than the first wall thickness. 
     Alternatively, or additionally, the frangible portion may comprise one or more perforations through the catheter shaft. 
     Alternatively, or additionally, the frangible portion may comprise one or more discontinuous recesses in an outer wall of the catheter shaft. 
     Alternatively, or additionally, the frangible portion may be disposed proximal of the balloon member. 
     Alternatively, or additionally, the frangible portion may be disposed on the balloon member. 
     Alternatively, or additionally, wherein two of the plurality of lumens merge into a single lumen. 
     Alternatively, or additionally, the catheter shaft may further comprise a mixing region disposed proximate the distal end of the shaft. 
     Alternatively, or additionally, the mixing region may comprise one or more barriers extending part way into one of the plurality of lumens. 
     Alternatively, or additionally, the mixing region may comprise a static helical mixer. 
     Alternatively, or additionally, the medical device may further comprise a biologically safe adhesive disposed on an outside of the balloon member. 
     Alternatively, or additionally, the balloon member may be integral with the catheter shaft. 
     Alternatively, or additionally, the balloon member may be a separate component from the catheter shaft. 
     Alternatively, or additionally, the balloon member may be connected to the catheter shaft with an adhesive that is soluble in an aqueous environment of blood. 
     Alternatively, or additionally, the balloon member may be compliant and configured to stretch to assume a shape of a vessel in which the balloon member is contained. 
     Alternatively, or additionally, one or more of the plurality of lumens may be a guidewire lumen. 
     Alternatively, or additionally, none of the plurality of lumens is a guidewire lumen. 
     In another illustrative embodiment, a medical device may comprise a catheter shaft having a distal end and a proximal end and including a plurality of lumens extending through at least a portion of the catheter shaft. In some embodiments, the medical device may further include a balloon member disposed proximate the distal end of the catheter shaft, and the catheter shaft may comprise a frangible portion disposed proximate the distal end of the catheter shaft for detaching the balloon member from the catheter shaft. 
     Alternatively, or additionally, the catheter shaft may have a first wall thickness proximal of the frangible portion, the frangible portion may have a second wall thickness, and the second wall thickness may be less than the first wall thickness. 
     Alternatively, or additionally, the frangible portion may comprise one or more perforations through the catheter shaft. 
     Alternatively, or additionally, the frangible portion may comprise one or more discontinuous recesses in an outer wall of the catheter shaft. 
     Alternatively, or additionally, the frangible portion may be disposed proximal of the balloon member. 
     Alternatively, or additionally, the frangible portion may be disposed on the balloon member. 
     Alternatively, or additionally, the catheter shaft may further comprise a mixing region disposed proximate the distal end of the catheter shaft. 
     Alternatively, or additionally, the mixing region may comprise a static helical mixer. 
     Alternatively, or additionally, the balloon member may be a separate component from the catheter shaft and adhesively or thermally connected to the catheter shaft. 
     Alternatively, or additionally, the adhesive may be soluble in an aqueous environment of blood. 
     Alternatively, or additionally, the balloon member may be integral with the catheter shaft. 
     Alternatively, or additionally, one of the plurality of lumens may be a guidewire lumen. 
     Alternatively, or additionally, none of the plurality of lumens is a guidewire lumen. 
     In still another illustrative embodiment, a medical device may comprise a catheter shaft having a distal end and a proximal end and including a plurality of lumens extending through at least a portion of the catheter shaft. In some embodiments, at least two of the plurality of lumens may merge into a single lumen. Additionally in some embodiments, the medical device may further include a balloon member disposed at the distal end of the catheter shaft, wherein the single lumen opens into the balloon member. The catheter shaft may further include a frangible portion disposed near the distal end of the catheter shaft for detaching the balloon member from the catheter shaft. 
     Alternatively, or additionally, the catheter shaft may have a first wall thickness proximal of the frangible portion, the frangible portion may have a second wall thickness, and the second wall thickness may be less than the first wall thickness. 
     Alternatively, or additionally, the frangible portion may comprise one or more perforations through the catheter shaft. 
     Alternatively, or additionally, the frangible portion may comprise one or more discontinuous recesses in an outer wall of the catheter shaft. 
     Alternatively, or additionally, the catheter shaft may further comprise a mixing region disposed proximate the distal end of the catheter shaft. 
     Alternatively, or additionally, the mixing region may comprise a static helical mixer. 
     In yet another illustrative embodiment, a method of forming a medical device comprises forming a catheter shaft having a proximal end and a distal end and including a plurality of lumens extending through at least a portion of the catheter shaft. The method may further comprise forming a balloon member on the catheter shaft proximal the distal end of the catheter shaft. In some embodiments, the method may further include weakening a distal portion of the catheter shaft to create a frangible region. 
     Alternatively, or additionally, the balloon member may be formed separately from the catheter shaft and attached to the catheter shaft. 
     The above summary of the present disclosure is not intended to describe each embodiment or every implementation of the present disclosure. Advantages and attainments, together with a more complete understanding of the disclosure, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings, in which: 
         FIG. 1  is a side plan view of a catheter in accordance with various embodiments of the present disclosure: 
         FIGS. 2A-2C  are example cross-sectional views of the catheter shown in  FIG. 1  as viewed along line A-A, in accordance with various embodiments of the present disclosure; 
         FIGS. 3A and 3B  are example views of the distal region of the catheter shown in  FIG. 1  with the balloon member in an un-inflated state, in accordance with various embodiments of the present disclosure; 
         FIG. 3C  is an example view of the distal region of the catheter shown in  FIG. 1  including a guidewire port, in accordance with various embodiments of the present disclosure; 
         FIG. 3D  is an example cross-sectional view of a frangible region of the catheter shown in  FIG. 3C , as viewed along line E-E of  FIG. 3C ; 
         FIG. 3E  is an example view of the distal region of the catheter shown in  FIG. 1  including a guidewire port, in accordance with various embodiments of the present disclosure; 
         FIG. 3F  is an example cross-sectional view of a frangible region of the catheter shown in  FIG. 3E , as viewed along line F-F of  FIG. 3E ; 
         FIGS. 4A and 4B  are example views of the distal region of the catheter shown in  FIG. 1  with the balloon member in an inflated state; 
         FIG. 5A  is an example cross-sectional view of the distal region of the catheter shown in  FIG. 1  including a frangible region, in accordance with various embodiments of the present disclosure; 
         FIGS. 5B and 5C  are example cross-sectional views of the distal region of the catheter shown in  FIG. 5A  as viewed along line B-B of  FIG. 5A ; 
         FIG. 6  is a cross-sectional view of the distal region of the catheter shown in  FIG. 1  including a frangible region, in accordance with various embodiments of the present disclosure; 
         FIG. 7  is an example plan view of the distal region of the catheter shown in  FIG. 1  including a frangible region, in accordance with various embodiments of the present disclosure; 
         FIG. 8  is an example plan view of the distal region of the catheter shown in  FIG. 1  including a frangible region, in accordance with various embodiments of the present disclosure; 
         FIG. 9A  is an example plan view of the distal region of the catheter shown in  FIG. 1  including a frangible region, in accordance with various embodiments of the present disclosure; 
         FIG. 9B  is an example cross-sectional view of the catheter shown in  FIG. 9A  as viewed along line C-C, in accordance with various embodiments of the present disclosure; 
         FIG. 10A  is an example plan view of the distal region of the catheter shown in  FIG. 1  including a frangible region, in accordance with various embodiments of the present disclosure; 
         FIG. 10B  is an example cross-sectional view of the catheter shown in  FIG. 10A , in accordance with various embodiments of the present disclosure; 
         FIG. 11  is an example cross-sectional view of the distal region of the catheter shown in  FIG. 1  including a detachable balloon member, in accordance with various embodiments of the present disclosure; 
         FIG. 12A  is an example cross-sectional view of the distal region of the catheter shown in  FIG. 1  with an integral balloon member in a deflated state, in accordance with various embodiments of the present disclosure; 
         FIG. 12B  is an example cross-sectional view of the distal region of the catheter shown in  FIG. 1  with an integral balloon member in an inflated state, in accordance with various embodiments of the present disclosure; 
         FIGS. 13A-13D  are example views of the catheter of  FIG. 1  in relation to a body cavity, in accordance with various embodiments of the present disclosure; 
         FIGS. 14A-C  are additional example views of the catheter of  FIG. 1  in relation to a collateral vessel, in accordance with various embodiments of the present disclosure; 
         FIG. 15  is an example cross-sectional view of the distal region of the catheter shown in  FIG. 1  including a mixing region, in accordance with various embodiments of the present disclosure; 
         FIG. 16  is an example cross-sectional view of the distal region of the catheter shown in  FIG. 1  including a mixing region, in accordance with various embodiments of the present disclosure; 
         FIG. 17  is an example cross-sectional view of the distal region of the catheter shown in  FIG. 1  including a mixing region, in accordance with various embodiments of the present disclosure; and 
         FIG. 18  is a flow diagram of an illustrative method for forming a medical device, for example catheter  10  as depicted with respect to  FIG. 1 . 
     
    
    
     While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the disclosure to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure. 
     DETAILED DESCRIPTION 
     For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification. 
     All numeric values are herein assumed to be modified by the term “about”, whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, the term “about” may be indicative as including numbers that are rounded to the nearest significant figure. 
     The recitation of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). 
     Although some suitable dimensions, ranges and/or values pertaining to various components, features and/or specifications are disclosed, one of skill in the art, incited by the present disclosure, would understand desired dimensions, ranges and/or values may deviate from those expressly disclosed. 
     As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. 
     The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The detailed description and the drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the disclosure. The illustrative embodiments depicted are intended to be only exemplary. Selected features of any illustrative embodiments may be incorporated into any other described embodiments unless clearly stated to the contrary. 
       FIG. 1  shows an exemplary catheter  10  in accordance with various embodiments of the present disclosure. In some cases, catheter  10  may be a guide or diagnostic catheter, and may have a length and an outside diameter appropriate for its desired use, for example, to enable intravascular insertion and navigation. For example, when catheter  10  is adapted as a guide catheter, catheter  10  may have a length of about 20-250 cm and an outside diameter of approximately 1-10 French, depending upon the desired application. In some cases, catheter  10  may be a microcatheter that is adapted and/or configured for use within small anatomies of the patient. For example, catheter  10  may be used to navigate to targets sites located in tortuous and narrow vessels such as, for example, to sites within the neurovascular system, certain sites within the coronary vascular system, or to sites within the peripheral vascular system such as superficial femoral, popliteal, or renal arteries. In some cases, the target site is a neurovascular site and may be located within a patient&#39;s brain, which is accessible only via a tortuous vascular path. However, it is contemplated that the catheter may be used in other target sites within the anatomy of a patient. An exemplary catheter that may be utilized in accordance with the various embodiments as described herein is shown and described in U.S. Pat. No. 8,182,465, which is incorporated herein by reference in its entirety for all purposes. 
     As shown in  FIG. 1 , catheter  10  can include elongate catheter shaft  12 . Elongate shaft  12  may generally extend from proximal portion  16  and proximal end  18  in distal direction D toward distal portion  20 . Although depicted as having a generally circular cross-sectional shape, it will be understood that elongate shaft  12  can have other cross-sectional shapes or combinations of shapes without departing from the scope of the disclosure. For example, the cross-sectional shape of the generally tubular elongate shaft  12  may be oval, rectangular, square, triangular, polygonal, and the like, or any other suitable shape, depending upon the desired characteristics. 
     In some cases, manifold  14  may be connected to proximal end  18  of elongate shaft  12 . The manifold may include hub  17  and/or other structures to facilitate connection to other medical devices (e.g., syringe, stopcocks, Y-adapter, etc.) and to provide access to one or more lumens defined within elongate shaft  12 . In some cases, hub  17  may include ports  6 ,  7 , and  8 , which provide individual access to one or more lumens extending through at least a portion of catheter  10 . Some example lumens that may extend through catheter  10  may include at least one guidewire lumen and one or more inflation lumens. The lumens that do extend through catheter  10  may terminate at or near distal portion  20  of elongate shaft  12 , as will be described with respect to other figures. However, in other cases, hub  17  may have a single port, two ports, or any other number of ports. Manifold  14  may also include a strain relief portion adjacent proximal end  18  of elongate shaft  12 . 
     Distal portion  20  of elongate shaft  12  may include balloon member  25 , shown in  FIG. 1  in a deflated state. In accordance with techniques described herein in greater detail, balloon member  25  may be detached from catheter  12  and act as an occlusive body. To facilitate detachment of balloon member  25  from elongate shaft  12 , elongate shaft  12  may include frangible region  24  disposed on distal portion  20  of elongate shaft  12 .  FIG. 1  depicts frangible region  24  including perforations  27 , however in other embodiments frangible region  24  may include additional or different features, as will be described in more detail below. In some cases, elongate shaft  12  may include additional devices or structures such as inflation or anchoring members, sensors, optical elements, ablation devices or the like, depending upon the desired function and characteristics of catheter  10 . 
       FIGS. 2A-2C  are all example cross-sections of elongate shaft  12  viewed along line A-A as depicted in  FIG. 1 . As described previously, elongate shaft  12  may have multiple lumens extending through at least a portion of elongate shaft  12 , for example lumens  31 ,  33 , and  35 . In some embodiments, lumen  33  may be a guidewire lumen and lumens  31 ,  35  may be inflation lumens. Lumens  31 ,  33 , and  35  may all be separate lumens along at least a portion of elongate shaft  12 .  FIG. 2A  depicts an example cross section of elongate shaft  12  where elongate shaft  12  has been made from a solid cylinder of material with lumens  31 ,  33 , and  35  set into the material and separate from outer wall  13  of elongate shaft  12 . In these embodiments, elongate shaft  12  may be formed, for example, by extrusion.  FIG. 2B  depicts an example cross section of elongate shaft  12  where lumens  31 ,  33 , and  35  are coextensive with at least a portion of wall  15  of elongate shaft  12  and separated by barrier  32  extending through elongate shaft  12 .  FIG. 2C  depicts elongate shaft  12  where lumens  31 ,  33 , and  35  are created by separate tubes  34 ,  36 , and  38  all residing within elongate shaft  12  lumen  39  of elongate shaft  12 . 
       FIG. 3A  depicts a close-up of distal portion  20  of elongate shaft  12 , according to some embodiments of the present disclosure.  FIG. 3A  depicts lumens  31 ,  33 , and  35  extending through distal portion  20  of elongate shaft  12 .  FIG. 3A  also depicts balloon member  25  in cross-section disposed around distal portion  20 . In some embodiments, as depicted in  FIG. 3A , lumens  31 ,  33 , and  35  may extend all the way to distal end  22  of elongate shaft  12 . In the embodiment of  FIG. 3A , lumens  31  and  35  may be inflation lumens and may have inflation ports  93  and  95  which connect inflation lumens  31  and  35  to the interior of balloon member  25 . Accordingly, when inflation media is pushed through inflation lumens  31  and  35 , the inflation media may enter balloon  25  through inflation ports  93 ,  95  and inflate balloon member  25 . In such embodiments, the distal ends of each inflation lumen  31 ,  35  may be sealed. In some of these embodiments, the distal end of guidewire lumen  33  may extend through balloon member  25  to a distal guidewire opening, or guidewire lumen  33  may terminate at a different location. For example, guidewire lumen  33  may terminate with a distal guidewire opening proximal of balloon  25  such that a guidewire may pass along an exterior of balloon  25 . In other instances, elongate shaft  12  may not include a guidewire lumen  33 . In some such instances, elongate shaft  12  may or may not include one or more additional lumens, such as a lumen for receiving a stiffening member or stylet therein. 
       FIG. 3B  depicts another close-up of distal portion  20  of elongate shaft  12 , in accordance with some embodiments. In the embodiment of  FIG. 3B , inflation lumens  31 ,  35  may terminate before distal end  22 . For instance, inflation lumens  31 ,  35  may merge to form a single lumen  37 . Inflation ports  93 ,  95  may then connect lumen  37  to the interior of balloon member  25 . Although  FIG. 3B  depicts inflation lumens  31 ,  35  merging proximal of frangible region  24 , in other examples, inflation lumens  31 ,  35  may merge distal of frangible region  24  (with proximal and distal directions identified by arrows P and D). For instance, inflation lumens  31 ,  35  may merge distal of frangible region  24 , but proximal of bonding region  29 . In other embodiments, inflation lumens  31 ,  35  may merge distal of both frangible region  24  and bonding region  29 , but distal of distal end  22 . As will be described in more detail below, in some embodiments, elongate shaft  12  may include a mixing region where inflation lumens  31 ,  35  merge in order to facilitate mixing of any media flowing through inflation lumens  31 ,  35 . In such embodiments, the mixing region may be located proximal or distal of frangible region  24 . 
     In the embodiments depicted in  FIGS. 3A and 3B , inflation lumens  31 ,  35  and guidewire lumen  33  may terminate at ports  6 ,  7 , and/or  8  on hub  17 . However, in other embodiments, as depicted in  FIGS. 3C and 3E , catheter  10  may be a single-operator-exchange catheter in which elongate shaft  12  may include a proximal guidewire port  41  at a proximal end of guidewire lumen  33  located distal of hub  17 . In the embodiments of  FIG. 3C , guidewire port  41  may be disposed distal of frangible region  24 . In some of these embodiments, region  47  of elongate shaft  12  proximal of guidewire port  41  may constitute a solid material. For instance, region  47  may be a portion of an outer wall of elongate shaft  12 . In other embodiments, however, region  47  may be part of inflation lumen  31  and/or  35 . For example, the combined cross-sectional area of inflation lumens  31 ,  35  proximal of guidewire port  41  may be greater than the combined cross-sectional area of inflation lumens  31 ,  35  distal of guidewire port  41 . 
       FIG. 3D  depicts a cross-section of frangible region  24  viewed along line E-E. As seen in  FIG. 3D , where guidewire port  41  is disposed proximal of frangible region  24 , elongate shaft  12  may include three lumens, lumens  31 ,  33 , and  35 , extending through frangible region  24 . In some embodiments, at least a portion of elongate shaft  12  may remain with balloon member  25  after balloon member  25  is detached from elongate shaft  12 . In such embodiments, elongate shaft  12  may include one or more frangible features. For instance, in the embodiment of  FIG. 3D , where elongate shaft  12  is a solid tube, recesses  28  may be formed in the outer wall  13  of elongate shaft  12 . Recesses  28  may mechanically weaken the portion of elongate shaft  12  in frangible region  24  such that when pulling or twisting forces are applied to elongate shaft  12 , elongate shaft  12  may break or separate along the frangible region  24 . In some embodiments, elongate shaft  12  may be extruded to have recesses  28 . However in other embodiments, recesses  28  may be formed after extrusion by removing material from elongate shaft  12 , such as by cutting or burning with laser ablation. 
     In the embodiment of  FIG. 3E , elongate shaft  12  may include a proximal guidewire port  41  at a proximal end of guidewire lumen  33  disposed distal of frangible region  24 . For example, guidewire port  41  may be disposed distal of frangible region  24  and proximal of bonding region  29 . As with some of the embodiments of  FIG. 3C , in some of the embodiments of  FIG. 3E , region  47  of elongate shaft  12  proximal of guidewire port  41  may constitute a solid material. For instance, region  47  may be a portion of an outer wall of elongate shaft  12 . In other embodiments, however, region  47  may be part of inflation lumen  31  and/or  35 . For example, the combined cross-sectional area of inflation lumens  31 ,  35  proximal of guidewire port  41  may be greater than the combined cross-sectional area of inflation lumens  31 ,  35  distal of guidewire port  41 . 
       FIG. 3F  depicts a cross-section of frangible region  24  viewed along line F-F. As seen in  FIG. 3F , where guidewire port  41  is disposed distal of frangible region, elongate shaft  12  may include only two lumens, lumens  31  and  35 , extending through frangible region  24 . Where at least a portion of elongate shaft  12  may remain with balloon member  25  after balloon member  25  is detached from elongate shaft  12 , elongate shaft  12  may include one or more frangible features such as recesses  28 . In some embodiments where elongate shaft  12  is a solid tube, elongate shaft  12  may be extruded to have recesses  28 . However in other embodiments, recesses  28  may be formed after extrusion by removing material from elongate shaft  12 , such as by cutting or burning with laser ablation. 
       FIG. 4A  depicts a close-up of distal portion  20  of elongate shaft  12  when balloon member  25  is inflated where elongate shaft  12 , or a distal region thereof is devoid of a guidewire lumen. For instance, elongate shaft  12  may have no guidewire lumen and may only have a single lumen which is an inflation lumen, or may have multiple (e.g., dual) inflation lumens, such as inflation lumens  31 ,  35 . In such embodiments, elongate shaft  12  may be configured to have different regions of varying stiffness. For instance, elongate shaft  12  may have regions that get progressively less stiff going from the proximal portion of elongate shaft  12  to the distal portion of elongate shaft  12 . In such embodiments, the varying stiffness may allow a user to apply pushing forces to elongate shaft  12 , yet have distal region  20  of elongate shaft  12  have a low enough stiffness to navigate a potentially tortuous path to the desired occlusion location. In at least some embodiments, elongate shaft  12 , or portions of elongate shaft  12 , may include one or more reinforcing members to help provide additional stiffness and/or to prevent any of the lumens of elongate shaft  12  from collapsing. For example, the one or more reinforcing member may comprise a coiled wire or a woven layer of material. 
     In embodiments in accordance with  FIG. 4A , balloon member  25  may only be bonded to elongate shaft  12  along bonding region  29  and may be disposed around distal end  22  of elongate shaft  12 . In these embodiments, distal end  22  of elongate shaft  12  may be sealed. In some embodiments, balloon member  25  may have a waist section  26  that is less compliant than the rest of balloon member  25 . Accordingly, when balloon member  25  is inflated, waist section  26  may retain its shape instead of becoming stretched like the other portion of balloon member  25 . Waist section  26  may additionally increase the overall diameter elongate shaft  12  in the area of bonding region  29 . This increase in diameter may help to bias detachment of balloon member  25  from elongate shaft  12  along frangible region  24 . 
       FIG. 4B  depicts yet another close-up of distal portion  20  of elongate shaft  12  when balloon member  25  is inflated and includes a guidewire lumen. As depicted in  FIG. 4B , elongate shaft  12  may include guidewire lumen  33  which extends all the way through balloon member  25 . In these embodiments, balloon member  25  may be an annular balloon that is bonded to elongate shaft  12  both along bonding region  29  and along bonding region  30 . The distal end of guidewire lumen  33  may be open, thereby allowing catheter  10  to be tracked over a guidewire. In these embodiments, a guidewire may be placed in position within a patient, and then catheter  10  may be placed over the guidewire and maneuvered into position over the guidewire. As depicted in  FIG. 4B , in some embodiments, ports  93 ,  95  may be the open ends of inflation lumens  31 ,  35 , instead of being disposed on the side walls of inflation lumens  31 ,  35 . In these embodiments, inflation lumens  31 ,  35  may terminate within balloon member  25 . 
     In embodiments where guidewire lumen  33  extends all the way through balloon member  25 , guidewire lumen  33  may have one or more properties to ensure a seal of guidewire lumen  33  after the guidewire is removed to ensure that balloon member fully occludes the region where it has been positioned. In some embodiments, the walls of guidewire lumen  33 , at least in the region within balloon member  25 , may be made from a low-durometer material. In such embodiments, when balloon member  25  is inflated, internal pressure from the inflation media may act to press against the walls of guidewire lumen  33  and seal the walls together—thereby preventing fluid from flowing through guidewire lumen  33 . In other embodiments, instead of employing a low-durometer material, the walls of guidewire lumen  33  may be thin and have a relatively low stiffness. In a similar manner to if the walls were made from a low-durometer material, when balloon member  25  is inflated, the internal pressure may act to squeeze the walls of guidewire lumen  33  closed. In still other embodiments, the frangible region of elongate shaft  12  may be designed such that when balloon member  25  is detached from elongate shaft  12 , the frangible region collapses to close guidewire lumen  33 . 
       FIG. 5A  depicts an example cross-section of distal region  20  of elongate shaft  12  including an example of frangible region  24  according to some embodiments of the present disclosure. Any internal lumens that elongate shaft  12  may include, for example those shown with respect to  FIG. 5B , have been removed from  FIG. 5A  for clarity purposes. In the embodiment of  FIG. 5A , wall  43  of elongate shaft  12  may have a first wall thickness proximal of frangible region  24  (with the proximal direction indicated by arrow P). Thin portion  45  of wall  43  in frangible region  24  may have a second wall thickness, where the second wall thickness is less than the first wall thickness. In some embodiments, elongate shaft  12  may continue extending distal of frangible region  24 , and wall  43  may also have the first wall thickness in the region distal of frangible region  24 . In other embodiments, wall  43  may have a third wall thickness distal of frangible region  24 . In some embodiments, the third wall thickness may be greater than the first wall thickness, however in other embodiments the third wall thickness may be less than the first wall thickness but greater than the second wall thickness. 
     In some embodiments, thin portion  45  may be made during manufacture by variably thinning wall  43  as elongate shaft  12  is being formed. In other embodiments, thin portion  45  may be formed after elongate shaft  12  has been created by removing material from elongate shaft  12  in frangible region  24  by one or more techniques well known in the art, such as by cutting away the material or using heat to burn away the material—for example with laser ablation. In other embodiments, thin portion  45  may be formed after elongate shaft  12  has been created by further processing, such as stretching or crimping a portion of elongate shaft  12 . 
       FIG. 5B  depicts an example cross-section of thin portion  45  viewed along line B-B, as depicted in  FIG. 5A . As seen in  FIG. 5B , thin portion  45  may have a wall thickness that is thinner than that of wall  43  in other regions of elongate shaft  12 . As depicted in  FIG. 5B , lumens  31 ,  33 , and  35  may all be separate lumens as defined by walls  34 ,  36 , and  38 , and reside within lumen  40  of elongate shaft  12 . However, in other embodiments, elongate shaft  12  may take a different form where lumens  31 ,  33 , and  35  are not defined by walls  34 ,  36 , and  38 . In the embodiment of  FIG. 5B , walls  34 ,  36 , and  38  may remain the same thickness even through frangible region  24 .  FIG. 5C  depicts another example cross-section of thin portion  45  viewed along line B-B. In the embodiment of  FIG. 5C , the wall thickness of walls  34 ,  36 , and  38  thins, similar to wall  43  of elongate shaft  12 , in infrangible region  24 . Of course, in other embodiments, less than all of the lumens that reside within elongate shaft  12  may include a thinned portion in frangible region  24 . In still other embodiments, one or more of walls  34 ,  36 , and  38  may have thinned portions in regions other than in frangible region  24 . 
     In general, thin portion  45  of wall  43  may be relatively more mechanically weak than the rest of wall  43  of elongate shaft  12 . As such, when mechanical stress is applied to catheter  10 , such as by pulling or twisting, elongate shaft  12  may preferentially break in frangible region  24 , thereby detaching balloon member  25  from the rest of elongate shaft  12 . For instance, elongate shaft  12  may break somewhere along thin portion  45 . Although, in other examples, elongate shaft  12  may generally, or at least sometimes, break at the interface between thin portion  45  and balloon member  25 , or somewhere along balloon member  25 . Additionally, where walls  34 ,  36 , and/or  38  do not also have thin portions, when balloon member  25  is detached from elongate shaft  12  and elongate shaft  12  is retracted, lumens  31 ,  33 , and  35  may remain intact and become extracted as elongate shaft  12  is pulled away from balloon member  25 . However, where walls  34 ,  36 , and/or  38  do have thin portions, after balloon member  25  is inflated and elongate shaft  12  is retracted, walls  34 ,  36 , and/or  38  may also break along in the region of their thin portions, leaving behind a portion of lumens  31 ,  33 , and  35  as part of detached balloon member  25 . Of course, as described, only some of walls  34 ,  36 , and/or  38  may have thin portions. In such embodiments, only those walls that have thin portions may leave behind portions of the lumens, while the other lumens may be entirely extracted as elongate shaft  12  is retracted. 
       FIG. 6  depicts another example cross section of distal region  20  of elongate shaft  12  including an example of frangible region  24 . In the example of  FIG. 6 , frangible region  24  includes crimped portions  51 . As with the example of  FIGS. 5A-5C , crimped portions  51  may be made during manufacture by variably thinning wall  43  as elongate shaft  12  is being formed. In other examples, crimped portions  51  may be formed after elongate shaft  12  has been created by removing material from elongate shaft  12  in frangible region  24  by one or more techniques well known in the art, such as by cutting away the material or melting or burning away the material—for example with a laser. In still other examples, crimped portions  51  may be created by mechanically compressing, or crimping, elongate shaft  12  in frangible region  24 . 
     As with thin portion  45  in the example of  FIG. 5A , crimped portions  51  may be relatively more mechanically weak than the rest of elongate shaft  12 . As such, when mechanical stress is applied to catheter  10 , such as by pulling or twisting, elongate shaft  12  may preferentially break in frangible region  24 , along crimped portions  51 , thereby detaching balloon member  25  from the rest of elongate shaft  12 . Although, in other examples, elongate shaft  12  may generally, or at least sometimes, break at the interface between frangible region  24  and balloon member  25 , or somewhere along balloon member  25 . Although not shown in  FIG. 6 , any lumens that reside within elongate shaft  12  may also have similar crimped portions  51 . In embodiments of  FIG. 6 , the number of lumens residing within elongate shaft  12  that include a frangible feature, and the location of any included frangible features on the included lumens, may be as described with respect to lumens  31 ,  33 , and  35  of  FIGS. 5A-5C . 
       FIG. 7  is a plan view of distal region  20  of elongate shaft  12  including an example of frangible region  24 . In the example of  FIG. 8 , frangible region  24  includes slits  53 . Slits  53  may be formed after elongate shaft  12  has been created by cutting into elongate shaft  12  in frangible region  24 . In some examples, slits  51  may extend all the way through wall  43  of elongate shaft  12 . In other examples, slits  51  may only extend through a portion of wall  43 . 
     As with thin portion  45  and crimped portions  51 , frangible region  24  including slits  53  may be relatively more mechanically weak than the rest of elongate shaft  12 . As such, when mechanical stress is applied to catheter  10 , such as by pulling or twisting, elongate shaft  12  may preferentially break in frangible region  24 , along slits  53 , thereby detaching balloon member  25  from the rest of elongate shaft  12 . Although, in other examples, elongate shaft  12  may generally, or at least sometimes, break at the interface between frangible region  24  and balloon member  25 , or somewhere along balloon member  25 . Although not shown in  FIG. 7 , any lumens that reside within elongate shaft  12  may also have similar slits  53 . In embodiments of  FIG. 7 , the number of lumens residing within elongate shaft  12  that include a frangible feature, and the location of any included frangible features on the included lumens, may be as described with respect to lumens  31 ,  33 , and  35  of  FIGS. 5A-5C . 
       FIG. 8  is a plan view of distal region  20  of elongate shaft  12  including an example of frangible region  24 . In the example of  FIG. 8 , frangible region  24  includes perforations  55 . Perforations  55  may be formed be after elongate shaft  12  has been created by puncturing elongate shaft  12  in frangible region  24  with rods or spikes or the like. Although perforations  55  in  FIG. 8  are depicted as circular, other examples may have differently shaped perforations. In  FIG. 8 , perforations  55  are depicted as openings in elongate shaft  12 . However, in other embodiments, perforations  55  may be small enough that they do not create appreciable openings in elongate shaft  12 . 
     Frangible region  24 , including perforations  55 , may be relatively more mechanically weak than the rest of elongate shaft  12 . As such, when mechanical stress is applied to catheter  10 , such as by pulling or twisting, elongate shaft  12  may preferentially break in frangible region  24 , along perforations  55 , thereby detaching balloon member  25  from the rest of elongate shaft  12 . Although, in other examples, elongate shaft  12  may generally, or at least sometimes, break at the interface between frangible region  24  and balloon member  25 , or somewhere along balloon member  25 . Although not shown in  FIG. 8 , any lumens that reside within elongate shaft  12  may also have similar perforations  55 . In embodiments of  FIG. 8 , the number of lumens residing within elongate shaft  12  that include a frangible feature, and the location of any included frangible features on the included lumens, may be as described with respect to lumens  31 ,  33 , and  35  of  FIGS. 5A-5C . 
       FIG. 9A  is a plan view of distal region  20  of elongate shaft  12  including an example of frangible region  24 . In the example of  FIG. 9A , frangible region  24  includes discontinuous recesses  57 . Discontinuous recesses  57  may be formed be after elongate shaft  12  has been created by selectively removing material from wall  43  in frangible region  24 . Some common techniques know in the art include removing material by cutting or by burning the material away with heat or lasers. In general discontinuous recesses  57  may not extend all the way through wall  43 . This can be seen in  FIG. 9B , which depicts an example cross-sectional shape of frangible region  24 , for instance as viewed along line C-C in  FIG. 9A . Although discontinuous recesses  57  in  FIG. 9A  are depicted as rectangular, other examples may have differently shaped perforations. 
     Frangible region  24 , including discontinuous recesses  57 , may be relatively more mechanically weak than the rest of elongate shaft  12 . As such, when mechanical stress is applied to catheter  10 , such as by pulling or twisting, elongate shaft  12  may preferentially break in frangible region  24 , along discontinuous recesses  57 , thereby detaching balloon member  25  from the rest of elongate shaft  12 . Although, in other examples, elongate shaft  12  may generally, or at least sometimes, break at the interface between frangible region  24  and balloon member  25 , or somewhere along balloon member  25 . Although not shown in  FIGS. 9A-9B , any lumens that reside within elongate shaft  12  may also have similar discontinuous recesses  57 . In embodiments of  FIGS. 9A-9B , the number of lumens residing within elongate shaft  12  that include a frangible feature, and the location of any included frangible features on the included lumens, may be as described with respect to lumens  31 ,  33 , and  35  of  FIGS. 5A-5C . 
     In the above described examples, frangible region  24  has been depicted disposed on elongate shaft  12  proximal of balloon member  25  and distal of guidewire port  23 . However, in other embodiments contemplated by this disclosure, frangible region  24  may be disposed in any of a number of different locations. For example, as depicted in  FIG. 10A , frangible region  24 , including perforations  55  only for exemplary purposes, may be disposed on balloon member  25 .  FIG. 10B  depicts an example cross-section of distal region  20  where frangible region  24  is included on balloon member  25 . In some embodiments, perforations  55  may extend all the way through balloon member  25  and wall  43  of elongate shaft  12 . Although shown as distinct openings in  FIG. 10B , in other embodiments, perforations  55  may be small enough that they do not create any appreciable opening or connection between the interior of balloon member  25  and/or elongate shaft  12  to the exterior of balloon member  25 . Again, any distinct lumens residing within elongate shaft  12  may or may not also have such frangible features, as described with respect to lumens  31 ,  33 , and  35  of  FIGS. 5A-5C . 
       FIG. 11  depicts yet another example cross-section of distal portion  20  of elongate shaft  12 . In the embodiment of  FIG. 11 , elongate shaft  12  may not have a frangible region. Rather, balloon member  25  may be attached to elongate shaft  12  using adhesive  61 . In these embodiments, adhesive  61  may be a soluble adhesive or a hydrophilic coating. For instance, adhesive  61  may include polyvinylpyrrolidone (PVP), polyethylene glycol (PEO), polyvinyl alcohol (PVA), sodium alginate, chitosan, polyacrylic acid, and/or polyacrylamide, or other suitable adhesives or hydrophilic coatings. 
     In these embodiments, adhesive  61  may temporarily attach balloon member  25  to elongate shaft  12 . Such soluble adhesives or hydrophilic coatings may be water soluble, or at least soluble in the aqueous environment of blood. After a sufficient amount of time exposed to the patient&#39;s blood or other solvent, the bond between balloon member  25  and elongate shaft  12  may weaken. In some instances, balloon member  25  may separate from elongate shaft  12  after exposure to blood or another solvent without external forces being applied. However, in other instances, some external force, such as a pulling or twisting of catheter  10 , may be used to separate balloon member  25  from elongate shaft  12 . In other embodiments, adhesive  61  may be exposed to a lumen of elongate shaft  12 . In such embodiments, an appropriate solvent (for example, water) may be injected in the lumen exposed to adhesive  61  to weaken the bond between balloon member  25  and elongate shaft  12 . 
     In the above described embodiments, elongate shaft  12  may be formed according to techniques known in the art. Balloon member  25  may then be adhesively or thermally attached to distal portion  20  of elongate shaft  12 . Balloon member  25  may be extruded using a compliant, low durometer, elastomeric material, such as silicone, thermoplastic polyurethane (TPU), SIBS (poly styrene-isobutylene-styrene block copolymer), polyurethane, SEBS styrene ethylene butylene styrene block copolymer, other styrenic block copolymers, or other suitable materials. Once balloon member  25  has been attached to elongate shaft  12 , a frangible region in accordance with this disclosure may be formed to create a detachable site. Although, in other embodiments, it is possible the frangible region is created on elongate shaft  12  before balloon member  25  is attached. In some additional embodiments, instead of being extruded onto elongate shaft  12 , balloon member  25  may be a separate tube section that is attached to elongate shaft  12  along distal portion  20 . In such embodiments, balloon member  25  may be compression-fitted, heat-bonded, laser-welded or otherwise attached to elongate shaft  12 . 
     However, in still additional embodiments, balloon member  25  and elongate shaft  12  may be formed in an integral manner.  FIGS. 12A and 12B  depict example cross-sections of distal portion  20  of elongate shaft  12  where elongate shaft  12  and balloon member  25  have been formed integrally, where balloon member  25  is in an uninflated state ( FIG. 12A ) and an inflated state ( FIG. 12B ). As elongate shaft  12  is formed, wall  43  may be variably thinned to produce balloon  25 . Once elongate shaft  12  and balloon member  25  have been formed, a frangible region may be created on elongate shaft  12  or balloon member  25 , as desired, for instance in accordance with any of the techniques discussed with respect to  FIGS. 3A-11 . 
       FIGS. 13A-13D  depict how catheter  10  may operate to occlude a cavity. In one embodiment, balloon member  25  may be guided to a location within vasculature  101  of a patient to occlude aneurysm  103 . In some instances, a guidewire (not shown) may be guided through vasculature  101  of the patient to the desired area, e.g. aneurysm  103 . Once the guidewire is in place, catheter  10  may be placed over the guidewire and threaded along the guidewire to arrive at aneurysm  103 . After balloon member  25  is positioned in aneurysm  103 , as shown in  FIG. 13A , balloon member  25  may be inflated, for example by injecting various gases, fluids, or foam-forming chemistries.  FIG. 13B  shows balloon member  25  partially inflated. 
     In some embodiments, balloon member  25  may further include biologically safe adhesive  71  disposed on the outer wall of balloon member  25 . Biologically safe adhesive  71  may act as a tissue sealant or a mucosal adhesive and may be safe for use within a human body. Some examples of biologically safe adhesive  71  include hydrogels comprised of polymers. One example hydrogel is a copolymer of vinyl pyrrolidone, acrylic acid, and N-hydroxysuccinimide. An example structure of such a copolymer is shown below: 
     
       
         
         
             
             
         
       
     
     Other example biologically safe adhesives include biomimetic adhesives comprising synthetic hydrogels (PEO as one example) modified with catechol functionality (mussel-like adhesives), and cross-linked polyacrylic acid and copolymers. Once balloon member  25  is disposed within aneurysm  103  fully expanded, biologically safe adhesive  71  may operate to secure balloon member  25  within aneurysm  103 . 
     As balloon member  25  is inflated, balloon member  25  may tend to conform to the shape of aneurysm  103 . Once fully inflated, as in  FIG. 13C , a force may be applied to catheter  10 , such as a retracting force or a twisting force. Balloon member  25  may be retained within aneurysm  103  in the face of the force applied to catheter  10  due one or more retaining forces. For example, aneurysm  103  may have a relatively small neck, which may operate to prevent inflated balloon member  25  from being pulled out of aneurysm  103 . Additionally, or alternatively, in examples where balloon member  25  includes biologically safe adhesive  71 , biologically safe adhesive  71  may secure balloon member  25  to the walls of aneurysm  103 . The securing force provided by biologically safe adhesive  71  may then operate to prevent balloon member  25  from being pulled out of aneurysm  103 . The opposing force on catheter  10  and the retention forces on balloon member  25  may be sufficient to break elongate shaft  12  along, or near, frangible region  24 . This breakage separates balloon member  25  from the rest of elongate shaft  12 , leaving balloon member  25  disposed within aneurysm  103 , as depicted in  FIG. 13D . 
       FIGS. 14A-14C  depict balloon member  25  being positioned and deployed in a collateral vessel. For instance, elongate shaft  12  may be guided into branch  175 . Once in position, balloon member  25  may be inflated, as depicted in  FIG. 14B . When balloon member  25  is inflated to the desired level, elongate shaft  12  may be retracted, and balloon member  25  may be detached from the rest of elongate shaft  12 , as in  FIG. 14C . 
     In some embodiments, balloon member  25  may be inflated with a polymer material, which may be a foam-forming polymer material. The polymer material reactants may individually initially have a sufficiently low viscosity to allow flow through elongate shaft  12  and into balloon member  25 . However, once the polymer material reactants have mixed, possibly along with application of heat or electricity, the polymer material reactants may harden into a solid polymer material or expanded foam. The solid polymer material or expanded foam may help to prevent blood from flowing into balloon member  25 , aneurysm  103 , and/or branch  175 . In other examples, the solidified polymer material or expanded foam may allow for some perfusion of blood into balloon member  25 , which may result in a clot forming within balloon member  25 . In these embodiments, the solidified polymer material or expanded foam may act to block blood from flowing into aneurysm  103 , or into/out of branch  175 . 
     In embodiments where the polymer material reactants are foam-forming reactants, the foam-forming reactants may be liquid. Once the reactants are mixed together, the liquid reactants may begin to expand in a foaming fashion and eventually harden. For instance, in some embodiments, the interior of balloon member  25  may be coated with a super absorbant polymer (SAP) such as lightly cross-linked poly sodium acrylate. When the balloon is inflated with water, the SAP swells resulting in gelation of the inflation media. In other embodiments, an aqueous solution (e.g. 1% solids) of polyacrylic acid may be injected into the balloon through a first lumen and an aqueous solution of base (e.g. NaOH or sodium bicarbonate) may be injected through a second lumen. Mixing of the two solutions may result in neutralization of the polyacrylic acid and forming gelled polysodium acrylate. In still other embodiments, a foam may be formed using a reaction according to equation (1). 
       isocyanate+polyol+water=polyurethane+CO2=polyurethane foam  (1)
 
     Example isocyanates that may be used include hexamethyline diisocyanate (HDI), toluene diisocyanate (TDI), xylene diisocyanate, methylene diphenyl diisocyanate (MDI), lysine diisocyanate, and isophorone diisocyanate. Example polyols that may be used include polyether, polybutadiene polyols, polysiloxane polyols, polypropylene glycols (PPG), and polyethylene glycols (PEG). 
     In general, by utilizing different reactants or reactants in varying proportions, foams having specific, differing properties may be formed. For instance, various foams used to inflated balloon member  25  may have pore size ranging from 5-500 micrometers and may have anywhere between 10-10,000 cells. Further, the stiffness of the foam may be controllable based on the types and quantities of the reactants used. In some embodiments, radiopaque materials may be added to balloon member, either before, during, or after inflation to make balloon member  25  easier to see on various medical imaging machines. 
     As described previously with respect to  FIGS. 3A-3B , in some embodiments, elongate shaft  12  may include a mixing region where two inflation lumens merge. The mixing region may help to evenly mix reactants used in a foam-forming reaction to inflate balloon member  25 .  FIGS. 15-17  depict different embodiments of a mixing region. 
       FIG. 15  is a cross-section of distal region  20  of elongate shaft  12  and an example mixing region  73 . In the example of  FIG. 15 , mixing region  73  is situated at the merging of inflation lumens  31 ,  35  into lumen  29 . Mixing region  73  comprises one or more barriers  81  that extend from inner wall  83  of elongate shaft  12  and/or from wall  36  that defines guidewire lumen  33  at least part-way into the lumen in mixing region  73 . In some examples, barriers  81  extend half-way, two-thirds, or three-quarters, or any other suitable distance into the lumen in mixing region  73 . Consecutive barriers  81  may extend into the lumen in mixing region  73  from different directions to create a tortuous flow path to encourage mixing between the gases or fluids flowing through lumens  31  and  35 . Although mixing region  73  is depicted proximal (with the proximal direction being indicated by arrow P) of frangible region  24 , in other embodiments, mixing region  73  may be located in other regions of elongate shaft  12 . For instance, in other embodiments, mixing region  73  may be located distal (with the distal direction being indicated by arrow D) of frangible region  24 . Although not shown in  FIG. 15 , one or more inflation ports (for instance, inflation ports  93 ,  95  as depicted in  FIGS. 3A-3B ) may place lumen  29  in communication with the interior of balloon member  25 , such that inflation media that flow through lumens  31 ,  35 , and  29  may inflate balloon member  25 . 
       FIG. 16  is a cross-section of distal region  20  of elongate shaft  12  and another example mixing region  73 . In the example of  FIG. 16 , mixing region  73  is situated at the merging of inflation lumens  31 ,  35  into lumen  29 . Mixing region  73  comprises one or more first barriers  85  and one or more second barriers  87 . First barriers  85  may be circular or other shaped barriers that are situated within the center of the lumen in mixing region  73 . First barriers  85  may be connected to inner wall  83  of elongate shaft  12  and from wall  36  of guidewire lumen  33  by small connecting arms spaced around first barriers  85 . In this manner, first barriers  85  allow for flow of liquids or gas around toward walls  43  and  36 . Second barriers  87 , on the other hand, may generally extend from inner wall  83  and wall  36  toward the center of the lumen of mixing region  73 . For instance, second barriers  87  may be solid membranes filling the entire lumen of mixing region  73  except for a hole in their centers. In this manner, fluid may flow through second barriers  87  through the center of the lumen of mixing region  73 . Alternating first barriers  85  and second barriers  87  in this manner may create a tortuous flow path to encourage mixing between the gases or fluids flowing through lumens  31  and  35 . 
     Although mixing region  73  is depicted proximal (with the proximal direction being indicated by arrow P) of frangible region  24 , in other embodiments, mixing region  73  may be located in other regions of elongate shaft  12 . For instance, in other embodiments, mixing region  73  may be located distal (with the distal direction being indicated by arrow D) of frangible region  24 . Additionally, although not shown in  FIG. 16 , one or more inflation ports (for instance, inflation ports  93 ,  95  as depicted in  FIGS. 3A-3B ) may place lumen  29  in communication with the interior of balloon member  25 , such that inflation media that flow through lumens  31 ,  35 , and  29  may inflate balloon member  25 . 
       FIG. 17  is a cross-section of distal region  20  of elongate shaft  12  and yet another example mixing region  73 . In the example of  FIG. 17 , mixing region  73  comprises static helical mixer  89 . Static helical mixer  89  creates a tortuous path for liquids or gases or flowing through lumens  31  and  35  to encourage mixing as during flowing along static helical mixer  89 . Although mixing region  73  is depicted proximal (with the proximal direction being indicated by arrow P) of frangible region  24 , in other embodiments, mixing region  73  may be located in other regions of elongate shaft  12 . For instance, in other embodiments, mixing region  73  may be located distal (with the distal direction being indicated by arrow D) of frangible region  24 . Additionally, although not shown in  FIG. 17 , one or more inflation ports (for instance, inflation ports  93 ,  95  as depicted in  FIGS. 3A-3B ) may place lumen  29  in communication with the interior of balloon member  25 , such that inflation media that flow through lumens  31 ,  35 , and  29  may inflate balloon member  25 . 
       FIG. 18  is a flow diagram of an illustrative method for forming a medical device, for example catheter  10  as depicted with respect to  FIG. 1 . Although  FIG. 18  will be described with respect to catheter  10  and  FIG. 1 , the method of  FIG. 18  may be used to form other medical devices. A first step may comprise forming a catheter shaft having a proximal end and a distal end, such as in step  201 . In some examples, the catheter shaft may include a plurality of lumens extending through at least a portion of the catheter shaft. For example, the plurality of lumens may be arranged as depicted in any of  FIGS. 2A-2C . However, in other examples, the plurality of lumens may be formed or arranged differently than depicted in  FIGS. 2A-2C . Additionally, in some examples, the catheter shaft may terminate in a balloon member, such as balloon member  25 . Next, a distal portion of the catheter shaft may be weakened to create a frangible region, as in step  203 . For example, the frangible region may comprise any of the frangible regions described above with respect to other Figures and be formed according to any of the disclosed techniques. 
     Those skilled in the art will recognize that the present disclosure may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Specifically, the various features described with respect to the various embodiments and figures should not be construed to be applicable to only those embodiments and/or figures. Rather, each described feature may be combined with any other feature in various contemplated embodiments, either with or without any of the other features described in conjunction with those features. Accordingly, departure in form and detail may be made without departing from the scope of the present disclosure as described in the appended claims.