Abstract:
A catheter comprising a first lumen for receiving a guidewire and having an exit opening at a distal tip of the catheter. A second lumen, adjacent the first lumen and separated from the first lumen by a common wall, the second lumen configured for receiving contrast fluid, wherein perforations are formed in the common wall; a guidewire in the first lumen the guidewire being configured to be capable of advancement distally to extend out of the exit opening, the guidewire having two conditions: a first condition in which the guidewire is advanced distally to block the perforations whereby fluid may not flow from the second lumen to the first lumen; a second condition in which the guidewire is withdrawn proximally to unblock the perforations whereby fluid may flow from the second lumen into the first lumen and thence out of the exit opening.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Application No. 61/702,189, filed Sep. 17, 2012 incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     The present invention relates to catheters for performing medical and surgical procedures inside cavities of a mammalian body. Specifically, the invention relates to a structure and method for arranging lumens in a catheter that are configured for transporting surgical devices and fluids required for performing a procedure at the distal end of the catheter. 
     Multi-lumen catheters have come into widespread use for conducting procedures inside cavities of the body. As a result, some catheters known in the art may have four lumens or more, providing for the transportation of liquids up and down the catheter, for one or more guide wires, and for a surgical device such as a rotating drill, or cutting element. Each lumen occupies space, and causes the catheter to assume an ever larger outside dimension. This is disadvantageous, especially at the distal end of the catheter where body lumens may be narrow. 
     Thus, there is a need in the art for a catheter that makes more efficient use of lumens that extend over the length of the catheter. This invention addresses these, and other needs. 
     SUMMARY OF THE INVENTION 
     In a preferred embodiment, the invention comprises a catheter having a first lumen for receiving a guidewire, the first lumen having an exit opening at a distal tip of the catheter. The catheter includes a second lumen, adjacent the first lumen and separated from the first lumen by a common wall, the second lumen configured for receiving contrast fluid. Perforations are formed in the common wall. A guidewire is positioned in the first lumen, the guidewire being configured to be capable of advancement distally to extend out of the exit opening, the guidewire having two conditions, namely: a first condition in which the guidewire is advanced distally to block the perforations whereby fluid may not flow from the second lumen to the first lumen; and, a second condition in which the guidewire is withdrawn proximally to unblock the perforations whereby fluid may flow from the second lumen into the first lumen and thence out of the exit opening. 
     In some embodiments, the first lumen is an internal lumen, and the second lumen is an external lumen. In further embodiments, a seal is provided in the first lumen to block fluid flowing proximally in the first lumen. In some embodiments, the seal is an O-ring seal. However, in other embodiments, no seal is provided and fluid may also flow proximally around the guidewire. However, it can be appreciated that the presence of the guidewire in the inner lumen will tend to compel most of the fluid to flow distally out of the distal tip exit. 
     In some embodiments, the catheter may include an outer cylinder that defines a plurality of openings that are configured to permit contrast fluid to flow from the second cylinder to a space external to the second cylinder. Such an arrangement may be utilized where additional contrast fluid is required. In some embodiments, the openings may have a slitted form, and are configured to be normally closed. In other embodiments, the openings may be circular. 
     In a further aspect, the invention is a method for discharging fluid from a distal end of a catheter. The method comprises advancing a guidewire distally through a first lumen of the catheter, and advancing fluid through a second lumen of the catheter. Initially, flow of the fluid from the second lumen into the first lumen is blocked, using the guidewire to block the flow. Then, the flow of fluid from the second lumen into the first lumen is unblocked by withdrawing the guidewire proximally, and causing the fluid to flow from the second lumen to the first lumen, and thence out of the distal end of the catheter. 
     These and other advantages of the invention will be understood by reference to the drawings and the detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a general schematic view of a catheter having features of the invention. 
         FIG. 2A  is a sectional view of a distal end of the catheter. 
         FIG. 2B  is a sectional view taken substantially through the line  2 B- 2 B in  FIG. 2A . 
         FIG. 3  is the view of  FIG. 2A , shown with a guidewire in a first condition. 
         FIG. 4  is the view of  FIG. 2A , shown with a guidewire in a second condition. 
         FIG. 5A  is a sectional view of another embodiment of the catheter. 
         FIG. 5B  is a sectional view taken substantially through the line  5 B- 5 B in  FIG. 5A   
         FIG. 5C  is a plan view on an optional embodiment of a perforation used in the catheter. 
         FIG. 6  is a detail view of an embodiment of a perforation used in the area marked “X” in  FIG. 5A , shown with a guidewire in a first condition. 
         FIG. 7  is the detail view of  FIG. 6  shown with a guidewire in a second condition. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the figures, there is described a catheter having features of the present invention.  FIG. 1  shows a catheter system generally identified by the numeral  10 . The catheter system includes a flexible element  12  for insertion into the patient&#39;s body by known means, and a handle  14  for controlling the operation of the flexible element  12 . The handle includes a first luer connector  16  for insertion of a guide-wire, and a second luer connector  18  for introducing contrast liquid. A guide-wire  20  is configured for sliding insertion into the handle and along the flexible element  12 . 
     The catheter  10  may be made of any suitable biocompatible material. In certain embodiments, catheter  10  is formed of polyurethane, which may include aliphatic or aromatic polyurethane. However, catheter  10  may alternatively be made of any suitable polymer such as polyamides, polyesters, polyolefins, fluoropolymer (such as fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), polyvinylidene fluoride (PVDF)), polyvinyl chloride (PVC), silicones (poly-dimethyl Siloxane), and so forth, as well as combinations. A number of manufacturing assemblies and procedures may be employed to make catheter  10 . For example, catheter  10  may be made by injection molding which is a manufacturing process for forming objects, utilizing thermoplastic or thermoset plastics, metals, or ceramic materials, by heating the molding material and injecting it into a mold. During injection molding, a molding material or resin is shaped to form a desired part or object. Most polymers, including thermoplastics, thermosets, and elastomers, may be used as molding materials. 
       FIGS. 2A and 2B  exemplify the distal end  22  of the flexible element  12 . At the distal end  22 , the flexible element comprises an outer cylinder  24 , and an inner cylinder  26  sized and configured for receiving the guide-wire  20 . A distal tip  28  having an internal bore  29  may be connected to the outer cylinder  24 , preferably by inserting an outer diameter portion  50  of the distal tip  28  into an internal diameter portion  52  of the outer cylinder  24  to provide a leak proof seal between distal tip and outer cylinder. The distal tip  28  may also be connected to the inner cylinder  26 , by inserting an outer diameter portion  54  of the inner cylinder  26  into an inner diameter portion  56  of the distal tip  28 , to provide a leak proof seal between distal tip and inner cylinder  26 . 
     At the distal end  22  of the flexible portion  12 , small openings  30  or perforations are formed in a wall of the inner cylinder, as seen in  FIGS. 2A and 2B . The openings may be formed by laser cutting or by punch cutting, and in one embodiment (seen in  FIG. 2A ) they may be circular. In another embodiment, openings  30 ′ may be created in the wall of the inner cylinder, and may be given a slitted form. In this embodiment, exemplified in  FIGS. 5A-5C , two intersecting slits may be cut into the wall of the inner cylinder  26  to produce four leaves  31 ′ which occupy each of four quadrants around a center point as seen in  FIG. 5C . In this configuration, the leaves may be flexible between open and closed conditions. 
     In one embodiment, the leaves  30 ′ may be configured to maintain the slitted opening  30 ′ in a “normally closed” condition—that is to say, the slitted openings are closed against each other and obstruct fluid flow when no forces are acting upon the leaves, while a force is required to open the leaves. In another embodiment, the leaves may be configured to maintain the slitted opening in a “normally open” condition—that is to say, the slitted openings are open and permit fluid flow when no forces are acting upon the leaves, while a force is required to close the leaves. A normally open condition may be created by applying heat to the slitted opening simultaneously with forcing the leaves to an open condition. Such may be accomplished by transmitting heated air, or fluid, through the openings and then rapidly transmitting chilled air or fluid to “set” the leaves in the open condition. The implications of these embodiments will be described below. 
     In some embodiments, each opening  30  (or  30 ′) follows the preceding opening down an axial path with an offset angle to provide a helical pattern to the openings and thereby maintain the structural integrity of the inner cylinder  26 . In some embodiments the offset angle is 90 degrees. In other embodiments, openings may be more numerous where the strength of the inner cylinder allows. 
     The resulting configuration of the distal end  22  of the flexible portion provides a structure in which the inner cylinder  26  defines an inner lumen  32  suitable for receiving the guidewire  20 . The guidewire may extend from the handle  14  all the way up the inner lumen  32 , and out of the bore  29  of the distal tip  28 , through a distal opening  34  in the flexible portion of the catheter. In the space between the inner cylinder  26  and the outer cylinder  24 , an outer lumen  36  is defined. Contrast fluid may pass under pressure from the handle (via contrast luer  18  by known pressurization means) all the way up the outer lumen  36  until it reaches the distal end  22  of the flexible portion  12 . Once fluid has passed up the outer lumen, it may be confronted by either of two conditions: 
     In a first condition of the catheter, as shown in  FIG. 3 , the guidewire  20  may be positioned distally beyond the distal end  34  within the inner lumen  32 , and in this condition may tend to block off the openings  30  (or  30 ′) in the wall of the inner cylinder. In this condition, the contrast fluid in the outer lumen  36  is blocked from passing through the openings  30  (or  30 ′) into the inner lumen  32 . 
     However, in a second condition of the catheter, as shown in  FIG. 4 , the guidewire  20  may be withdrawn proximally along the inner lumen  32 , so that the openings  30  (or  30 ′) in the wall of the inner cylinder are not blocked. In this condition, the contrast fluid that has been introduced under pressure up the outer lumen  36  may pass from the outer lumen  36  through the openings  30  (or  30 ′) into the inner lumen  32 , as shown by the arrows in  FIG. 4 . Here, the guidewire  20  merely blocks the passage of the fluid in a proximal direction along the inner lumen  32 , from a location proximal to the openings  30  (or  30 ′), and thus compels the contrast liquid to flow distally, out of the distal tip  29  and out of the distal opening  34  of the catheter. To enhance the effectiveness of this fluid flow action, the guidewire  20  may be caused to pass through a valve that seals the perimeter of the guidewire to the internal diameter wall of the inner cylinder  26  so that proximal flow of the fluid is prevented. Such a valve may be positioned in the handle  14  at the guidewire luer  16 , or may be positioned distally comprising a rubber gasket or O-ring  35  ( FIG. 5A ) through which the wire must pass, and which seals the perimeter of the guidewire against fluid flow in a proximal direction along inner lumen. In some embodiments, the seal is an O-ring seal. However, in other embodiments, no seal is provided and fluid may also flow proximally around the guidewire. It can be appreciated that the presence of the guidewire in the inner lumen will tend to compel most of the fluid in the inner lumen to flow distally out of the distal tip exit. 
     Turning now to two optional embodiments of the slitted openings  30 ′ as described above: As noted, the slitted openings may be configured to be either normally closed, or normally open. 
     Where the openings are configured to be normally closed, the fluid in the outer lumen  36  will tend to be blocked by the leaves  31 ′ of the openings  30 ′. However, if the leaves tend to leak even in the closed condition under some pressure, the guidewire may be positioned distally in the first condition to assist in the blocking and prevention of any fluid flow through the openings  30 ′. When the guidewire is withdrawn proximally to the second condition, the fluid may be pressurized sufficiently to allow the fluid pressure to force the leaves inward to thus open the slitted openings  30 ′, and the fluid may flow into the inner lumen  32  and thence out of the distal exit opening  34  as described above. 
     Where the openings  30 ′ are configured to be normally open, (as may be envisaged with reference to  FIG. 7  in which the leaves  31 ′ reside normally in an inward position) and the guidewire is withdrawn proximally as in the second condition, the fluid in the outer lumen  36  is free to flow through the normally open slitted openings  30 ′ into the inner lumen  32 , and thence out of the distal exit  34 . However should the treating physician wish to close off the openings and terminate the fluid flow, she may advance the guidewire distally to the first condition. The advancing guidewire forces the leaves  31 ′ of the slitted openings  30 ′ upwards to close the openings as may be envisaged with reference to  FIG. 6 . 
     Thus, the added feature of providing slitted openings (either normally open or normally closed) may assist in providing perforations that have added ability to be provide a better seal at desired stages of operation. 
     Thus, the configuration of the present invention allows the guidewire lumen  32  to have two functions, that can be altered by altering the condition, or position, of the guidewire  20 . Depending on the position of the guidewire  20 : First, the guidewire lumen  32  may act to carry the guidewire  20  for placement of the catheter flexible portion  12 . Second, the guidewire lumen  32  may act to allow contrast fluid to discharge from the very tip  29  of the catheter, at a location where the procedure is to be performed. This ability to switch uses of the guidewire lumen  32  by the simple means of adjusting the position of the guidewire has a considerable advantage over prior art devices in which perfusion openings have been provided along the external length of the distal end of a catheter, somewhat behind the tip of the catheter and not at the tip, thus giving rise to a cloud of contrast fluid at a location which is not at the very location of the procedure. The present invention overcomes this shortcoming by allowing the contrast fluid to discharge from the very tip of the catheter at the very location of the procedure. 
     In some embodiments, the catheter may include an outer cylinder  24  that defines a plurality of openings  33 ′ that are configured to permit contrast fluid to flow from the second cylinder  24  to a space external to the second cylinder. Such an arrangement may be utilized where additional contrast fluid is required. In some embodiments, the openings may have a slitted form, and are configured to be normally closed. In other embodiments, the openings may be circular. 
     Thus, the catheter provides an advantageous structure for reducing the outside dimension of a catheter, by using lumens within the catheter for multiple functions. The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, while the scope of the invention is set forth in the claims that follow.