Abstract:
A catheter used to deliver or retrieve material from within a body. The catheter comprises a proximal end, a distal end and a central section extending between the proximal end and the distal end. The catheter also includes an internal lumen that extends from the proximal end to the distal end through the central section. The distal end includes a rigid bulbous tip with an outer diameter that is greater than an outer diameter of the central section. The rigid bulbous tip has a rounded, substantially spherical shape that is safer than the distal end of a traditional catheter. The bulbous tip does not include any sharp edges that could tear or otherwise perforate a passageway within a patient. As a result, the catheter is safer and it can be advanced within the patient without causing pain or injury.

Description:
[0001]    The present invention relates to a medical instrument with an atraumatic end that will not cause injury as it is advanced within a patient, more specifically, the present invention relates to a medical instrument with an internal lumen and an atraumatic distal end that is free of any edges that could cut or perforate a patient while at least a portion of the instrument is being introduced and positioned in a passageway within the body of the patient.  
         BACKGROUND OF THE INVENTION  
         [0002]    Many medical procedures require that a medical instrument, such as a catheter, be introduced into a passageway in the body for various reasons. These catheters are traditionally positioned and advanced into a passageway within the body. These passageways include, but are not limited to, breast ducts and other fluid carrying vessels such as blood vessels. The term “vessel” is used herein to refer to tubular and tubular-like structures within the body that carry, or are capable of carrying, fluids, cells, waste or compositions of any or all of these.  
           [0003]    Conventional catheters have internal lumens that form passageways through which fluids or other materials are introduced and/or removed from the body. In many conventional procedures, a catheter is used to introduce fluids into a body and retrieve fluids and other compositions from within the body. One such procedure for determining if a typical cells exist in a breast duct is known as ductal lavage.  
           [0004]    Conventional catheters include distal ends that are normally introduced into a body opening and advanced within an associated passageway using an internally positioned dilator. These known catheters have inner and outer walls and are typically cylindrical in shape. The inner and outer sidewalls each terminate at a distal edge that form a stepped shoulder that can make a sharp angle with a distal face of the catheter. These transition shoulders typically include ninety-degree angles that are capable of cutting, perforating or otherwise injuring a patient as the catheter is advanced within a body passageway. This is especially true when the distal end is passed into an area of a body passageway that has a constriction or sphincter with an opening that is smaller than the outer diameter of the catheter. At the very least, these angles and the orientation of the distal surface can cause a patient a great deal of discomfort while the catheter is being advanced within the body passageway. The discomfort is significantly increased when the catheter is passed without the use of a dilator.  
         SUMMARY OF THE INVENTION  
         [0005]    An aspect of the present invention relates to a medical instrument with an atraumatic end that will not penetrate or tear a portion of a body opening or passageway. The medical instrument according to the present invention is safer to use within a mammalian body than conventional instruments.  
           [0006]    One aspect of the present invention relates to a catheter for inserting in a body. The catheter comprises a proximal end, a distal end and a central section extending between the proximal end and the distal end. The catheter also includes an internal lumen that extends from the proximal end to the distal end through the central section. The distal end includes a rigid teardrop or elliptical shaped tip with an outer diameter that is greater than an outer diameter of the central section. The rounded surface(s) of the rigid elliptical end is safer than the end of a traditional catheter because it does not include any transition shoulders or sharp edges that could tear or otherwise perforate a passageway within a patient. As a result, the catheter will not cause pain or injury to a patient as it is advanced in a passageway within the patient. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 illustrates a medical instrument according to the present invention positioned within a breast duct;  
         [0008]    [0008]FIG. 2 is a side view of the medical instrument illustrated in FIG. 1;  
         [0009]    [0009]FIG. 3 is a perspective view of the medical instrument illustrated in FIG. 2;  
         [0010]    [0010]FIG. 4 is a cross-sectional view taken along the line  4 - 4  of FIG. 3;  
         [0011]    [0011]FIG. 5 is an alternative embodiment of the cross-sectional view taken along the line  4 - 4  of FIG. 3;  
         [0012]    [0012]FIG. 6 is an alternative embodiment of the cross-sectional view taken along the line  4 - 4  of FIG. 3;  
         [0013]    [0013]FIG. 7 is an alternative embodiment of the medical instrument according to the present invention with a portion broken away;  
         [0014]    [0014]FIG. 8 illustrates a medical instrument according to the present invention positioned within an external dilator; and  
         [0015]    [0015]FIG. 9 is a cross sectional view of an alternative embodiment of the medical instrument according to the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    As illustrated in the figures, the present invention relates to a medical instrument  10  that is positioned within a body passageway  1  during a medical procedure. Medical instrument  10  can include a shunt, a stent, a catheter, or any other instrument used to introduce fluids into the body and/or remove fluids from within the body. The instrument  10  can also include those medical instruments that are used to introduce compositions of fluids and medicaments, therapeutic or diagnostic agents into the body and/or remove compositions of bodily fluids, introduced agents, introduced fluids and/or portions of the body (including cells and cell clumps) from within the body.  
         [0017]    For ease of explanation, the medical instrument  10  will be described as it relates to a catheter that is inserted into a breast duct  1  before or during a ductal access procedure, such as ductal lavage, in order to introduce a fluid into the breast duct  1  and remove a composition of bodily fluids and cells from within the duct  1 . However, the catheter  10  according to the present invention is not limited to being used with ductal lavage procedures. Instead, as discussed above, it can be used in any type of a medical procedure that includes the insertion of a device including an open ended lumen into a body opening or passageway.  
         [0018]    As shown in FIG. 2, the catheter  10  includes a proximal end  12 , a distal end  14  and a central section  11  extending between the ends  12 ,  14 . The proximal end  12  is similar to a proximal end of a conventional catheter. For example, the proximal end  12  has a centrally positioned opening  18  that forms a first end of an internal lumen  20 . Additionally, proximal end  12  can be rigid enough that it can be grasped by a practitioner and used to steer the catheter  10  within the duct  1 . Any conventional medical device that can be operatively connected to a proximal end of a conventional catheter can also be connected to the proximal end  12  of the catheter  10 . For example, a fluid source could be operatively connected to end  12  in order to introduce fluids into the catheter  10  and ultimately into the body. Similarly, a collection system, with or without a vacuum source, can also be operatively connected to the proximal end  12 . A system having both fluid and negative pressure sources can also be connected to the proximal end  12 .  
         [0019]    The internal lumen  20  is defined by an inner sidewall  22  that extends from an outer face  13  of the proximal end  12 , along the length of the catheter  10  and to an outer, distal face  15  of the distal end  14  as shown in FIG. 3. The diameter of the inner lumen  20  is substantially the same or larger than that of conventional catheters. Similarly, the diameter of the inner lumen  20  can vary from catheter to catheter depending upon the size and purpose of the catheter  10 . For example, the diameter of lumen  20  may be greater for a catheter used to deploy a balloon expandable stent within a vascular vessel than for a catheter used to recover clumps of cells from within a breast duct. No matter the purpose of the catheter, the diameter of the inner lumen  20  can be constant along the length of the catheter  10  or it can vary. In one embodiment, the diameter of the lumen  20  will taper from a point along the length of the catheter  10  to the distal end  14 . The internal lumen can have a diameter of between about 0.010 inch and about 0.035 inch. In one embodiment, the diameter of the internal lumen is between about 0.015 inch and 0.030 inch. In another embodiment, the diameter of the internal lumen is about 0.022 inch.  
         [0020]    The outer diameter of the central section  11  of the catheter  10  is between about 0.020 inch and about 0.040 inch. In another embodiment, the outer diameter is between about 0.025 inch and about 0.035 inch. In another embodiment, the outer diameter is about 0.030 inch.  
         [0021]    As shown in FIG. 4, the distal end  14  of the catheter  10  has a rigid, non-expandable atraumatic distal tip  30  that reduces the number of perforation or tearing injuries that are possible when a conventional catheter is advanced within a body passageway. The distal tip  30  has a substantially rounded (bulbous) shape that is void of any straight line edges resulting from the intersection of two more sections of the distal end  14  of the catheter  10 . The distal, bulbous tip  30  could also have a substantially teardrop, elliptical, or other type of oval shape. Unlike the distal tips of conventional catheters, the distal tip  30  does not include an edge that may catch or otherwise snag a portion of a passageway within the patient.  
         [0022]    As illustrated in FIG. 3, the bulbous tip  30  has an outer diameter that is greater than the outer diameter of the central section  11 . As a result, the lower hemisphere  32  and the region immediately above the equator  38  of the bulbous tip  30  forms the portion of the distal end  14  that contacts the epithelial lining  40  of the breast duct  1  as the catheter  10  is advanced within the duct  1 . As can be appreciated, these portions are rounded so that they are free of all sharp edges. Additionally, when the bulbous tip  30  encounters a constriction or sphincter  42  in the duct  40 , the rounded sidewall  34  of the rounded lower hemisphere  32  will engage and gradually dilate the constriction  41  or sphincter  42  without perforating or cutting the lining of the duct  40 . By engaging the lining of the duct and any area of reduced cross section within the duct with the rounded sidewall  34  of the lower hemisphere  32 , the catheter  10  will not damage the epithelial lining  40  as it is advanced through the duct  1  without the aid of a dilator.  
         [0023]    As discussed above, the diameter of inner lumen  20  can be constant or can taper along the length of the catheter  10 . The outer diameter is substantially constant from the proximal end  12  through the central section  11 . Alternatively, the outer diameter could increase from a point along central section  11  to the proximal end  14  of the bulbous tip  30 . This gradual increase in the outer diameter provides additional lateral support to the bulbous tip  30 .  
         [0024]    At the distal end  14 , the outside diameter of the distal tip  30  at the equator  38  is between about 0.020 inch and about 0.040 inch. In another embodiment, the outer diameter of the distal tip  30  is between about 0.027 inch and about 0.037 inch. In another embodiment, the outer diameter of the distal tip  30  is about 0.032 inch.  
         [0025]    The length of the catheter  10  inserted into the body during a medical procedure, including the central section  11  and the distal end  14 , is between about 10.55 inch and 1.0 inch. In another embodiment, this length is between about 0.65 inch and 0.90 inch. In another embodiment, the length is about 0.787 inch (20 mm). In these embodiments, the length of the distal tip  30  at the distal end  14  is between about 0.055 inch and about 0.20 inch and the length of the central section  11  that is inserted into the body is between about 0.50 inch and about 0.80 inch. In these embodiments, the length of the distal tip  30  can be between about 0.075 inch and 0.175 inch and the inserted length of central section  11  can be between about 0.562 inch and 0.762 inch. Also, the length of the distal tip  30  can be about 0.125 inch and the inserted portion of central section  11  about 0.662.  
         [0026]    The total length of the catheter  10  above the portion of point along central section  11  that is inserted into the body can be the same as the length for the portion inserted into the body. For example, the length above the portion of central section  11  inserted into the body can be about 0.787 inch (20 mm).  
         [0027]    The space between the inner sidewall  22  of the lumen and the outer wall  33  of the bulbous tip  30  can be solid as shown in FIG. 4. Alternatively, it can be partially solid or hollow as shown in FIGS. 5 and 6, respectively. In the partially solid embodiment, a honeycomb shaped structure  36  is located between the outer wall  33  and the inner sidewall  22 , as shown in FIG. 5, to provide structural support to the bulbous tip  30 . The structure  36  resists the collapsing of outer wall  33  as the catheter is advanced through the duct  40 .  
         [0028]    The catheter  10  is formed of the same rigid biocompatible materials as conventional catheters. In the hollow and partially solid embodiments, the material used for the catheter  10 , especially for bulbous end  30 , must be strong enough to resist collapsing in response to the forces applied to it by the ductal walls. Known materials include metals and plastics. Examples of metals used are stainless steel, nickel-titanium. One type of metal commonly used is stainless steel. Conventionally used plastics include polycarbonate, polyimides, F.E.P. Teflon, and polyurethane.  
         [0029]    In an alternative embodiment shown in FIG. 7, an upper hemisphere  50  of the bulbous tip  30  includes a catch basket  52  for retrieving cell clumps or other materials from within the duct  40 . In a preferred embodiment, circumferentially spaced rails  54  extend between the lower hemisphere  32  and the central section  11  or an upper portion of the upper hemisphere  50  to form the catch basket  52 . As shown in FIG. 7, adjacent rails  54  are separated from each other by spaces  55 . Each space  55  forms an opening to an internal receiving portion  56  of the basket  52  that is shown in the broken away area in FIG. 7. During the insertion and removal of the catheter  10  within the duct  40 , cells that are dislodged from the epithelial lining of the duct  40  behind the bulbous tip  30  are collected in the catch basket  52  while cells in front of the bulbous tip  30  are drawn into the bulbous tip  30  and the inner lumen  20  through opening  24  in a similar manner to that disclosed in U.S. patent application Ser. No. 09/473,510 to Hung et al. which is hereby incorporated by reference. Similarly, the basket  52  can be used to collect cells from branches of the duct that extend ninety degrees to the main branch of the duct. Typically, the ninety-degree branches are difficult to access. Therefore, the bulbous head can be passed beyond these branches so that the cell clumps flushed from these braches can be collected in basket  52  and removed from the duct.  
         [0030]    In any of the above-discussed embodiments, a conventional dilator  70  having a proximal end  72  and a distal end  74  can be used to introduce the catheter  10  into the duct  1  as shown in FIG. 1. As with conventional internally positioned dilators, the distal end  74  extends beyond distal end  14  of the catheter  10  in order to gradually dilate the ductal opening. Alternatively, as shown in FIG. 8, an externally positioned, expandable dilator  80  disclosed in the copending U.S. Provisional Patent Application to Hung et al. entitled “Externally Positioned Medical Dilator” that is expressly incorporated herein by reference, can be used to dilate the ductal orifice in order to prepare it to receive the bulbous tip  30  as discussed in the above-mentioned application. As shown in FIG. 8, the bulbous tip  30  is positioned within the expandable, external dilator  80  so that the transition between the bulbous tip  30  and the dilator  80  is prevented from contacting the patient.  
         [0031]    Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims. For example, as shown in FIG. 9, a portion of the bulbous end  30  above the equator  38  may have rounded flanges that form an open receiving space between the central section  11  of the catheter and the inside wall of the bulbous end below the flanges. These flanges would prevent the ends of the walls of the bulbous end from scoring or tearing the walls of the duct during the removal of the catheter.