Patent Publication Number: US-9844642-B2

Title: Microcatheter system

Description:
RELATED APPLICATION 
     The present application claims priority benefit of U.S. Provisional Application No. 62/159,543, filed 11 May 2015 and entitled “Microcatheter System”, the entirety of which is hereby incorporated herein by reference. 
    
    
     FIELD 
     This disclosure relates to a microcatheter system, including a system having a microcatheter and a microcatheter extension and/or a microcatheter hub, where a unique joining mechanism couples two of the components together. 
     BACKGROUND 
     Microcatheters, including endovascular and neuroendovascular microcatheters, are generally microtubes inserted into the body through a blood vessel such as the femoral artery and have a variety of uses. Typically, microcatheters have a distal and a proximal end, where at or close to the distal end a marker band is employed for visualization of microcatheter positioning during in vivo use. The marker band typically comprises a metal or metal alloy ring such as platinum, nitinol and/or gold rings which can be visualized via fluoroscopy. 
     Microcatheters are typically used to embolize the neurovasculature such as in treating arteriovenous malformations (AVMs), aneurysms, and the like in a relatively non-invasive manner. Microcatheters with sufficient flexibility and size for applications in small tortuous vessels have been developed but typically require the continuous use of a guide catheter. 
     A wide variety of commercially available microcatheters have been developed for insertion in the vascular system for a number of diagnostic or therapeutic applications. Certain applications, however, require a small diameter and very flexible catheter to access small tortuous vessels in situ. Guide catheters of larger diameter are usually employed to act as a conduit to help support microcatheter access. One problem associated with the removal of guide catheters is the increased risk associated with thromboembolic and vascular wall injury complications. It would be beneficial to have a microcatheter system that can remain in situ at a desired vascular location without the need for a larger diameter guide catheter to also remain in situ. 
     SUMMARY 
     An aspect of at least one of the embodiments described herein includes the realization that it is advantageous to provide microcatheters which can remain in situ at a desired vascular location without the need for a larger diameter guide catheter to also remain in situ. It is further advantageous to provide microcatheters which easily are extensible and safely detachable/attachable in situ microcatheters with a unique joining mechanism which couples, for example, a microcatheter with a microcatheter extension without requiring an increase in the diameter of the microcatheter system at the joint. The unique joining mechanism is sometimes referred to herein as an internal Luer lock mechanism. The matching parts (male (probe) and female (receptacle) portions as described in further detail below) of the unique joining mechanism may be secured together by, for example, press fitting so that the matching parts remain in place due to friction. 
     According to one aspect of the present disclosure, a microcatheter system is described which includes a microcatheter having a distal end and a proximal end, wherein an internal diameter is constant throughout, and wherein the microcatheter includes a plurality of zones each zone having an outside diameter that is different from the outside diameter of each of the other zones in the plurality of zones; wherein the proximal end of the microcatheter is configured as a first receptacle for receiving a first probe for connecting a first microcatheter extension or a microcatheter hub to the microcatheter, and wherein an outside diameter of the first receptacle is no greater than a largest diameter of the zones in the plurality of zones; and the first microcatheter extension having a distal end and a proximal end, wherein an internal diameter is constant throughout, and wherein an outside diameter is constant throughout, and wherein the distal end of the first microcatheter extension is configured as the first probe to be received by the first receptacle of the proximal end of the microcatheter, and wherein an outside diameter of the first probe is less than an internal diameter of the first receptacle, wherein the internal diameter of the microcatheter is the same as the internal diameter of the first microcatheter extension, and wherein an outside diameter of the first microcatheter extension is the same as the outside diameter of the largest diameter of the zones in the plurality of zones. 
     According to another aspect of the present disclosure, a microcatheter system is described which includes a microcatheter having a distal end and a proximal end, wherein an internal diameter is constant throughout, and wherein the microcatheter includes a plurality of zones each zone having an outside diameter that is different from the outside diameter of each of the other zones in the plurality of zones; wherein the proximal end of the microcatheter is configured as a first probe for connecting to a first receptacle for connecting a first microcatheter extension or a microcatheter hub to the microcatheter, and wherein an outside diameter of the first probe is less than an internal diameter of the first receptacle; and the first microcatheter extension having a distal end and a proximal end, wherein an internal diameter is constant throughout, and wherein an outside diameter is constant throughout, and wherein the distal end of the first microcatheter extension is configured as the first receptacle to receive the first probe of the proximal end of the microcatheter, and wherein an outside diameter of the first receptacle is no greater than a largest diameter of the zones in the plurality of zones, wherein the internal diameter of the microcatheter is the same as the internal diameter of the first microcatheter extension, and wherein an outside diameter of the first microcatheter extension is the same as the outside diameter of the largest diameter of the zones in the plurality of zones. 
     Numerous other advantages and features of the present disclosure will become readily apparent from the following detailed description, the accompanying drawings, and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not necessarily to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Like reference numerals denote like features throughout specification and drawings. 
         FIG. 1  is a schematic illustration of a microcatheter in accordance with one embodiment. 
         FIG. 2  is a schematic illustration of a microcatheter extension in accordance with one embodiment. 
         FIG. 3  is a schematic illustration of the connection between a microcatheter and a microcatheter extension in accordance with one embodiment. 
         FIG. 4  is a schematic illustration of a connection between a microcatheter and a microcatheter hub, or the connection between a microcatheter extension and a microcatheter hub in accordance with one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     This description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as “lower,” “upper,” “horizontal,” “vertical,”, “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivative thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. 
       FIG. 1  illustrates a notional schematic of a microcatheter according to an embodiment of the present disclosure. The microcatheter  100  is designed along standard neuroendovascular microcatheter platforms with a generally tubular body to allow for the delivery of, e.g., detachable coil systems, particulate matter injections, as well as liquid injection and infusions in either a transient and/or in situ continuous manner. The microcatheter  100  has a distal end  110 , which is also marked as A, a proximal end  150 , which is also marked as E, and a transition portion. The transition portion of the microcatheter  100  includes four distinct zones from  110  to  120  is zone AB, from  120  to  130  is zone BC, from  130  to  140  is zone CD, and from  140  to  150  is zone DE. In one embodiment, zone AB and zone BC are usually disposed inside a body, while zone CD and zone DE are usually disposed outside the body. 
     In an embodiment, the tubular body of the microcatheter  100  has an increasing outer diameter (“OD”) in the direction from the distal end to the proximal end. For example, the outer diameter of zone AB is no greater than the outer diameter of zone BC, the outer diameter of zone BC is no greater than the outer diameter of zone CD, the outer diameter of zone CD is no greater than the outer diameter of zone DE. 
     In another embodiment, more than four zones are employed. In another embodiment, fewer than four zones are employed. In another embodiment, more than two zones are placed inside the body. In yet another embodiment, fewer than two zones are placed inside the body. 
     In one embodiment, the transition in outer diameter between any two abutting zones is a step change. In another embodiment, the transition in outer diameter between any two abutting zones is a gradual change. In another embodiment, the transition in outer diameter between any two abutting zones is a taper change. In another embodiment, the transition in outer diameter between any two abutting zones is a chamfer change. In another embodiment, the transition in outer diameter between any two abutting zones is a fillet change. One of skill in the art will readily understand that the current disclosure encompasses situations where more than one type of transition occurs along the length of a microcatheter such as, for a non-limiting example, a step change occurs between a first two abutting zones and a tapering change occurs between a second two abutting zones. 
     One advantage of the microcatheter described herein is that the substantially increased proximal outer diameter of the microcatheter and microcatheter extension increases the stability of the overall microcatheter system. 
     In one embodiment, the overall length of the microcatheter  100  is 150 cm and may optionally include one or two distal radio-opaque markers for visualization with detachable coil deployment. In one embodiment, the microcatheter  100  employs a nitinol braiding system throughout the entire length which enables improved stability. In one embodiment, the inner diameter of the microcatheter  100  remains constant at 0.4138 mm throughout the entire length of the microcatheter  100 . In another embodiment, the inner diameter of the microcatheter  100  remains constant at approximately 0.4 mm. 
     In one embodiment, zone AB is 30 cm in length and 0.57 mm in outer diameter (or 1.7 Fr); zone BC is 15 cm in length, and 0.73 mm (or 2.2 Fr) in outer diameter; zone CD is 15 cm in length, and 1.17 mm (or 3.5 Fr) in outer diameter; zone DE is 90 cm in length, and 1.33 mm (or 4 Fr) in outer diameter. 
     As would be apparent to one of ordinary skill in the art, the exemplary length or lengths listed above for any one or more zone may be different without departing from the spirit and intent of the present disclosure. Similarly, the exemplary inner diameter may be different without departing from the spirit and intent of the present disclosure. Likewise, the exemplary outer diameters listed above for any one or more zone may be different without departing from the spirit and intent of the present disclosure. 
     In one embodiment, the proximal end  150  (E) of the microcatheter  100  contains a female portion of a unique joining mechanism (e.g., female internal Luer lock mechanism) by which either the microcatheter extension  200  in  FIG. 2  or  FIG. 3  or the detachable/attachable microcatheter hub  400  in  FIG. 4  may be attached and/or detached. This unique design allows the microcatheter  100  to be utilized as a standard microcatheter or as an exchange length microcatheter. In another embodiment, the proximal end  150  (E) of the microcatheter  100  contains a unique male portion of the unique joining mechanism (e.g., male internal Luer lock mechanism) by which either the microcatheter extension  200  or the detachable/attachable microcatheter hub  400 , each having a unique female internal Luer lock mechanism, may be attached and/or detached. The internal Luer lock mechanism allows the microcatheter extension  200  to be coupled to the microcatheter  100  in such a manner as to allow the safe and effective removal of commonly employed guide catheter from the parent artery, allowing for continued treatment through the microcatheter  100  for a prolonged manner and decreasing the risk associated with thromboembolic complications. 
       FIG. 2  illustrates a notional schematic of a microcatheter extension  200  according to an embodiment of the present disclosure. In an embodiment, this microcatheter extension  200  is similar in material and configuration in terms of inner diameter and outer diameter as zone DE of the microcatheter  100  shown in  FIG. 1 . In one embodiment, the overall length of the microcatheter extension  200  from  210  to  220 , or A′E′ is 150 cm, the inner diameter  213  throughout remains the same as the inner diameter of the microcatheter  100 , which, in an embodiment, may be 0.4138 mm, and the outer diameter throughout remains the same as the outer diameter of zone DE, which is 1.33 mm. Other lengths and diameters of the microcatheter extension  200  are contemplated in keeping with the principles of the present disclosure. 
       FIG. 3  illustrates a notional schematic of the internal Luer lock mechanism connection  300  according to an embodiment of the present disclosure. In one embodiment, at the distal end  210  of the microcatheter extension  200  (A′) is a unique male internal Luer lock mechanism  211  which allows for connection to the proximal end  150  of either the microcatheter  100  or another microcatheter extension  200 . At the proximal end  150  of the microcatheter  100  is a unique female internal Luer lock mechanism  151 . At the proximal end  220  of the microcatheter extension (E′) is a unique female internal Luer lock mechanism which is identical in design to the mechanism found at the proximal end  150  of the microcatheter  100  (as shown at E in  FIG. 3 ). This allows for connection with either an additional microcatheter extension  200  or detachable/attachable microcatheter hub  400  ( FIG. 4 ). Internal diameter  153  is constant as described above. 
     In an alternate embodiment, the respective male and female portions are swapped between the connecting components. For example, at the distal end of the microcatheter extension  210  (A′) is a unique female internal Luer Lock mechanism which allows for connection to the proximal end  150  of either the microcatheter  100  or microcatheter extension  200 . At the proximal end  220  of the microcatheter extension  200  (E′) is a unique male internal Luer lock mechanism which is identical in design to the mechanism found at the proximal end  150  of the microcatheter  100 . 
     One advantage of the microcatheters described herein is that the unique Luer lock mechanism permits attachment and detachment of the microcatheter extension in tandem and/or with a microcatheter hub. Effectively creating an extended microcatheter with a detachable hub permits the safe and effective removal of a standard guiding catheter in standard exchange technique. This also allows the microcatheter described herein to be used as a standard endovascular/neuroendovascular microcatheter for standard, commonly employed procedures as well as increased utility when coupled with other components of the system. 
       FIG. 4  illustrates a notional schematic of the internal Luer lock connection between a microcatheter  100 , or a microcatheter extension  200 , and a microcatheter hub  400  having a distal end  410  and a proximal end  420 , according to an embodiment of the present disclosure. In an embodiment, the microcatheter hub  400  is similar in design and composition to the standard endovascular microcatheter proximal aspect; a standard female Luer lock mechanism permits connection with standard Luer lock syringes, connectors, and intravenous tubing. In an embodiment, the detachable/attachable microcatheter hub  400  distal aspect  411  is unique in that it possess a unique male internal Luer lock system which permits connection to either the proximal aspect  151  of either the microcatheter  100  or microcatheter extension  200 . The proximal end  420  of the microcatheter hub  400  is designed on a similar platform to the standard microcatheter hubs, e.g., having a standard Luer lock receptacle  421 , which allows for connection with standard Luer lock syringes, additional adapters such as three-way connectors and rotating hemostatic valves, as well as intravenous tubing to permit passage of detachable coil systems, particular matter, continuous liquid infusions, as well as syringe injections. Internal diameter  412  may be constant throughout as described above. 
     In another embodiment, the detachable/attachable microcatheter hub  400  distal aspect is unique in that it possess a unique female internal Luer lock system which permits connection to either the proximal aspect  150  of either the microcatheter  100  or microcatheter extension  200 . The ability to attach or detach the detachable/attachable microcatheter hub  400  permits the use of the microcatheter  100  as either a standard endovascular, or neuroendovascular microcatheter and/or as an exchange length microcatheter. The detachable/attachable microcatheter hub  400  is compatible with Dimethyl-Sulfoxide, and possess a pressure rating identical to the standard endovascular or neuroendovascular microcatheters. 
     One advantage of the microcatheters described herein is the improved performance of the microcatheters and increased safety with the exchange technique. 
     Although the subject matter has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments, which may be made by those skilled in the art.