Abstract:
A catheter design and method is provided for the aspiration of thrombus, clot, atherosclerotic emboli in the vascular bed. The aspiration catheter includes an aspiration lumen, a guidewire lumen having an exchange port, and a recess in the aspiration unit. The aspiration catheter lumen is divided into two sections: (i) proximal, and (ii) distal. The distal section has a distal opening.

Description:
BACKGROUND 
     Field 
       [0001]    This disclosure generally relates to medical devices and more particularly to catheters used for aspiration. 
       SUMMARY 
       [0002]    A catheter design and method is provided for aspiration, such as the aspiration of thrombus, clot, and/or atherosclerotic emboli in the vascular bed. The aspiration catheter includes an aspiration lumen, a guidewire lumen having an exchange port, and a recess in the aspiration lumen. The aspiration catheter lumen is divided into two sections: (i) proximal, and (ii) distal. The distal section has a distal opening. 
         [0003]    The exchange port is configured between the distal segment and the proximal segment. In one implementation, the catheter comprises an elongated aspiration lumen defined by a selectively laser cut pattern from the proximal to distal end (or reinforced shaft), providing an optimal stiffness profile that permits the catheter to navigate tortuous anatomy. Over the distal portion (e.g., 10-20 cm) an axial recess is cut to permit the seating of the rapid exchange guidewire lumen, which is subsequently bonded to the aspiration lumen. The recess cut into the aspiration lumen improves the catheters efficient use of cross sectional area (CSA), thereby offering a maximum CSA for aspiration. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  illustrates a catheter having a guidewire lumen, consistent with an embodiment of the present disclosure. 
           [0005]      FIG. 2  illustrates a cross section of a distal portion of a catheter, consistent with an embodiment of the present disclosure. 
           [0006]      FIG. 3  illustrates another cross section of a distal portion of a catheter, consistent with an embodiment of the present disclosure. 
           [0007]      FIG. 4  illustrates a sectional view of a catheter device, consistent with an embodiment of the present disclosure. 
           [0008]      FIG. 5  illustrates a cross section of a spiral cut hypotube, consistent with an embodiment of the present disclosure. 
           [0009]      FIG. 6  is a perspective view of the distal portion of the catheter. 
           [0010]      FIG. 7  is an end view of the catheter showing dimensions of a certain embodiment. 
           [0011]      FIG. 8  is an end view of the catheter. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0012]    In coronary heart disease the vasculature of the heart may have clot burden in the atherosclerotic vessels, which limit or restrict flow in these vessels. Traditionally, the physician would cross the lesion with a guidewire prior to advancing a Plain Old Balloon Angioplasty (POBA) to create a patent lumen (e.g., an inner open space or cavity of a tube having an internal diameter that is free from blockages or occlusion and capable of wire passage). The physician would then follow-up with the placement of a bare metal or drug eluting stent (DES), pinning the plaque and clot between the struts and the wall of the vessel. Applicants have recognized from clinical studies the improved patient outcomes when the soft clot burden or atherosclerotic debris in the coronary vessels is removed prior to stenting. In this regard, the concepts discussed herein disclose a novel and effective method and apparatus to remove this clot burden. 
         [0013]      FIG. 1  illustrates a catheter, consistent with an embodiment of the present disclosure. Catheter  100  includes an aspiration lumen  102  and a guidewire lumen  104 . The guidewire lumen  104  includes an exchange port  106 . In one aspect of the present disclosure, a recess  120  is included in the aspiration lumen  102 . A segment of the aspiration lumen  102  is substantially removed over the distal portion of the aspiration lumen to seat the guidewire lumen. A guidewire lumen may be a “Rapid Exchange” (Rx) lumen (e.g., a catheter where only the distal portion is delivered over the guide wire.) For example, the guide wire vents (e.g., exits) out through a side port and runs externally and parallel to the catheter proximal to this port. Thus, the guide wire lumen runs off center with respect to the aspiration lumen  102 . Such configuration substantially improves (i.e., effectively maximizes) the aspiration lumen cross sectional area while keeping the overall profile of the assembly small. For example, the configuration discussed herein is smaller than commercial catheter designs (e.g. Medtronic Export Catheter). In one embodiment, the overall profile of the system is compatible with a guide catheter having ≦0.070″ internal diameter, which is representative of a 6F Guide catheter (i.e., the workhorse catheter for coronary intervention). 
         [0014]    Reference now is made to  FIGS. 2 and 3 , which illustrate cross sections of a distal portion of a catheter, consistent with embodiments of the present disclosure.  FIG. 2  illustrates a catheter  200  having an aspiration lumen  202 , a guidewire lumen  204  on one side of the catheter  200 , and shrink tubing  208  around the aspiration lumen  202  and guidewire lumen  204 . By configuring the guidewire lumen at the side of the aspiration lumen  202 , the predetermined cross sectional area (C.S.A) of the aspiration lumen  202  is improved. 
         [0015]      FIG. 3  illustrates a cross section of a catheter  300  having several features similar to those discussed in the context of  FIG. 2 . By way of example,  FIG. 3  provides dimensions of components that may be used in an exemplary catheter  300 , consistent with an embodiment of the present disclosure. Unlike conventional configurations, where the distal end of the aspiration lumen is deformed to form a crescent shape cross sectional (e.g., in an effort to keep the outer diameter profile to a minimum), the embodiment of  FIG. 3  achieves a similar result by replacing the portion of the aspiration luminal wall circumference with the wall of the guidewire lumen  304 . Accordingly, there is minimal loss to the aspiration C.S.A. Put differently, the cross sectional area of the aspiration lumen is substantially improved (e.g., maximized). 
         [0016]      FIG. 4  illustrates a sectional view of a catheter device  400 , consistent with an embodiment of the present disclosure. In the example of  FIG. 4 , the catheter aspiration lumen  402  is segmented into 2 sections: (1) over the wire (OTW) distal section  416 ; and (2) the proximal section (e.g., aspiration lumen)  402 . The distal OTW section  416  of the catheter  400  is defined by the guide wire lumen  404  that travels in line with the aspiration lumen  402 . Thus, the distal OTW section  416  is the portion of the catheter that travels over a guidewire  404 . The OTW section  416  is defined by an exchange port  406  along the shaft and the tip  412  at the end of the catheter device  400 . For example, a guidewire passes through the chamfered aspiration lumen  402  at the exchange port  406  and the guidewire extends beyond the smaller wire lumen (i.e., guidewire lumen) at the distal end  416  (where both tubes terminate). Thus, the guidewire does not terminate at the end of the catheter but extends beyond it. During a procedure, the guidewire is positioned in the patient&#39;s vessel first and the aspiration lumen travels over the guidewire. In one embodiment, section  416  is the only portion of the catheter device  400  that encapsulates the guidewire. 
         [0017]    In one implementation, OTW distal section  416  comprises a stainless steel hypotube  414 . For example, the hypotube  414  may have a selectively cut laser pattern, which provides an optimal stiffness profile giving the user better control in delivery and support when positioned at the target treatment site. 
         [0018]    Referring back to  FIG. 3 , in one example, a recess may be cut into the machine cut hypotube shaft over the OTW distal section  416 . This recess  310  permits the guidewire lumen  304  to be seated. As discussed above, this section of the aspiration tubing wall is replaced by the guidewire tubing wall, when seated. Accordingly, the C.S.A of the aspirating lumen  302  is substantially preserved. That is because the guidewire lumen  304  does not obstruct the aspiration lumen  302  the way that prior art guidewire lumens do, as discussed above. 
         [0019]    Referring back to  FIG. 2 , in one implementation, a shrink tube  208  comprising Pebax or Fluorinated Ethylene Propylene (FEP) polymer is placed over the hypotube (e.g., aspiration lumen ( 202 )) and guidewire lumen  204  to join them and provide a fluid tight seal between the aspiration lumen  202  and guidewire wire lumen  204  of the catheter assembly  200 . For example, the proximal aspiration lumen  402  (see  FIG. 4 ), from the wire exchange port  406  to the hub  426 , may comprise a laser cut tube having a material substantially similar to that of the hypotube  414 . 
         [0020]      FIG. 5  illustrates a cross-sectional view of a spiral cut hypotube  514 , consistent with an embodiment of the present disclosure. The proximal aspiration lumen  502  may be enclosed in a shrink tubing  518  or a polymer tube reinforced with a metal coil or braid with a hub attached to the proximal end. Such configuration provides a fluid tight seal up to the aspiration port  436 , allowing a vacuum to be applied to remove material (e.g., thrombus &amp;/or debris) into a lock syringe (not shown). For example, in one embodiment, the lock syringe may be an accessory used during the procedure and part of the device  400 . 
         [0021]    One factor that may limit the size of the C.S.A of the aspiration lumen  302  is the overall diameter profile restriction that may result from the stack-up of aspiration lumen  302  with the guidewire lumen  304  diameter in the distal end  416  of the assembly  400 . In this regard, commercially available devices that are compatible with a 0.070″ catheter lumen or a 6F guide catheter are generally limited to an outer diameter profile of less than or equal to 0.067″. 
         [0022]    By way of example, calculations are provided below for C.S.A&#39;s of a catheter, consistent with an embodiment of the present disclosure, and compared to the largest known commercially available technology compatible with a 6F Guide. The percentage gain in C.S.A as compared to a known commercial device is also calculated. 
         [0023]    In commercial designs the aspiration lumen may have a diameter of approximately 0.043″. In this regard, the C.S.A=π·r̂2, where r=0.0215. Accordingly, the corresponding C.S.A=1.45×10 −3  in 2 . 
         [0024]    In contrast, based on the concepts discussed herein, an exemplary aspiration lumen diameter may have a diameter of approximately 0.048″. In this regard, the C.S.A=π·r̂2, where r=0.0215. Accordingly, the corresponding C.S.A=1.81×10 −3  in 2 , which is substantially larger than the C.S.A calculated above for the prior art. 
         [0025]    Subtracting the portion of the C.S.A that is replaced by the guidewire lumen (see  FIG. 3 ), which may be 4.01×10 −5  in 2 , provides a C.S.A in the aspirating lumen of approx. 1.77×10 −3  in 2 . The value of 4.01×10 −5  in 2  in this example may be a value provided when seating the guidewire lumen into the aspiration lumen. The C.S.A. of each lumen may be calculated an estimate made as to how much the small lumen removed from the large aspiration lumen. 
         [0026]    Thus, the calculations above demonstrate by comparing the C.S.A. of 1.77×10-3 in 2  of the exemplary embodiment to a commercially available design of 1.45×10-3 in 2 , that there is a 22% increase in cross sectional area while the overall outer diameter of the exemplary embodiment is approx. 0.067″ on the maximum O.D. 
         [0027]      FIG. 6  is a perspective view of a portion of the catheter  600 . The catheter includes an aspiration catheter  602  of a generally cylindrical, hollow overall shape. The aspiration catheter  602  has a free end  604  that is transverse to the length of the catheter  602 . The catheter  602  extends a length greater than shown in the drawing, as indicated at  606 . The aspiration catheter  602  has been shaped to have a recess  608  that extends from the free end  604  to a rounded or semicircular end  610  along a portion of the length of the aspiration catheter  602 . The recess  608  forms an opening through the wall of the aspiration catheter  602 . In the illustrated embodiment, the recess has a width that extends about over approximately 20 percent of the circumference of the aspiration catheter. Other widths, lengths, and shapes are possible for the recess  608 . 
         [0028]    A guidewire lumen  612  has a generally cylindrical, hollow overall shape and of a smaller diameter than the aspiration catheter  602 . The guidewire lumen  612  is affixed in the recess  608  s as to extend parallel to the aspiration catheter  602  with a smaller portion of the guidewire lumen  612  extending into the recess  608  and a larger portion of the guidewire lumen  612  extending outside the aspiration catheter  602 . The guidewire lumen  612  is affixed to the aspiration catheter  602  such as by welding or other means. The guidewire lumen  612  extends nearly the full length of the recess  608  from the free end  604  of the aspiration catheter  602  to near the rounded end  610  of the recess  608 . The end of the guidewire lumen  612  near the rounded end  610  of the recess  608  has an angled exchange port  614 . 
         [0029]      FIG. 7  shows the aspiration catheter  602  of  FIG. 6  with the guidewire lumen  612  mounted thereto. In the illustrated example, the interior diameter of the aspiration catheter  602  is 1.22 mm, the thickness of the walls of the aspiration catheter is 0.05 mm, the interior diameter of the guidewire lumen is 0.41 mm and the wall thickness of the guidewire lumen is 0.05 mm. The entire assembly fits within a circle of diameter 1.65 mm. 
         [0030]      FIG. 8  shows the end view of the aspiration catheter  602  of  FIGS. 6 and 7 . The opening in the aspiration catheter that holds the guidewire lumen  612  is approximately 35 to 40 degrees or about 20 percent of the circumference of the aspiration catheter. In one example, the guidewire lumen  612  extends over about 37 degrees of the aspiration catheter  60 . 
         [0031]    The components, steps, features, objects, benefits and advantages that have been discussed are merely illustrative. None of them, or the discussions relating to them, is intended to limit the scope of protection in any way. Numerous other embodiments are also contemplated. These include embodiments that have fewer, additional, and/or different components, steps, features, objects, benefits and advantages. These also include embodiments in which the components and/or steps are arranged and/or ordered differently.