CROSS-REFERENCE TO RELATED APPLICATION(S)  
       [0001]    The subject application claims the benefit of priority to U.S. Provisional Patent Application No. 60/364,649, filed Mar. 15, 2002, and U.S. Provisional Patent Application No. 60/391,793, filed Jun. 27, 2002, the disclosures of which are herein incorporated by reference in their entireties. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The subject disclosure relates to a vascular introducer assembly, and more particularly, to a vascular introducer assembly that includes a dilator, a sheath for accommodating the dilator, a locking mechanism for temporarily securing the dilator and the sheath to one another and an adjustable hemostatic seal for limiting fluid egress from the introducer assembly.  
           [0004]    2. Background of the Related Art  
           [0005]    The percutaneous introduction of diagnostic and/or therapeutic devices such as pacemaker leads and cardiovascular catheters into a blood vessel is typically accomplished with the aid of an introducer assembly. Introducer assemblies generally include a dilator having a tapered end portion and a thin-walled introducer sheath having a lumen extending therethrough to initially accommodate the dilator, and subsequently accommodate the passage of a pacemaker lead or catheter therethrough.  
           [0006]    Typically, the percutaneous introduction of an introducer assembly is accomplished by first inserting a needle into the blood vessel at a desired location and its position is verified by observing fluid return or by a similar method. While the needle is held firmly in place, a guidewire is inserted through the needle caimula to the desired depth. The guidewire is then held in place and the needle is withdrawn. Pressure is applied on the puncture site in order to minimize blood loss. Next, the introducer assembly is threaded over the guide wire. The introducer assembly is grasped close to the skin surface and advanced through the tissue to the desired position. Then, the dilator and guidewire are removed, leaving the sheath installed. A lead, catheter or similar diagnostic or therapeutic device is then introduced into the sheath and advanced to the desired position. Lastly, the sheath is removed, leaving the device disposed within the blood vessel of the patient.  
           [0007]    It is known to configure an introducer sheath in such a manner so that it may be easily removed or separated from the lead or catheter after it has been emplaced. For example, it is known to provide score lines in the wall of the sheath to enable the sheath to be pealed away, slit or split open. Once the sheath is removed and catheter is emplaced, therapeutic medical devices such as endocardial pacing/defibrillation leads may be introduced into the blood vessel through the catheter.  
           [0008]    Occasionally, the dilator slides out of the sheath during the insertion of the introducer assembly into a blood vessel. This significantly complicates the insertion procedure because the introducer assembly may not slide smoothly into the blood vessel and the insertion may not be effective. In some instances, when the dilator slides out of the sheath during insertion, the sheath may proceed completely through the vein, and break, bend, or tear. Also, if the dilator separates from the central lumen of the sheath, blood may flow undesirably from the vessel through the sheath.  
           [0009]    In addition, once the sheath is inserted into a blood vessel, it provides a passage for the free flow of blood. This may result in significant blood loss to the patient. The sheath also provides an open passage for the introduction of air into the vein. This could cause an embolism in the venous system of the patient. To overcome these problems, vascular introducers have been developed with hemostatic valves that prevent the free flow of blood through the introducer sheath.  
           [0010]    Examples of such prior art devices are disclosed in U.S. Pat. No. 5,124,904 to Lee and U.S. Pat. No. 5,409,463 to Thomas et al., the disclosures of which are incorporated herein by reference in their entireties. In each of these devices, the hemostatic valve is configured in such a manner so that it creates frictional resistance to the passage of therapeutic devices such as flexible cardiac leads. This makes introduction of the lead difficult and can actually cause damage to the lead.  
           [0011]    It would be beneficial therefore, to provide a vascular introducer having a sheath with a hemostatic seal that may be selectively, radially adjusted to accommodate frictionless, unobstructed passage of a diagnostic or therapeutic device therethrough. Furthermore, there is a need for a vascular introducer assembly that provides a mechanism for securely locking the dilator and sheath together during insertion of the introducer assembly to prevent axial movement of the dilator relative to the sheath.  
         SUMMARY OF THE INVENTION  
         [0012]    The present invention provides a vascular introducer which overcomes the problems associated with the prior art.  
           [0013]    In particular, the present invention is directed to a vascular introducer which includes an elongated dilator having a tapered distal end portion; an elongated hollow sheath having opposed proximal and distal end portions and an axial lumen extending therethrough to accommodate the dilator; and a selectively adjustable annular seal operatively associated with the proximal end portion of the sheath and configured for movement of the axial lumen between an open position in which the passage of instruments through the axial lumen is unrestricted and a closed position in which insertion of an instrument through the axial lumen is restricted.  
           [0014]    The vascular introducer of the present invention may also include a hub which is operatively associated with the proximal end portion of the sheath. This hub has a body portion including an axial passage to accommodate the dilator therein and for being in fluid communication with the axial lumen, a distal end portion and a proximal end portion.  
           [0015]    The vascular introducer of the present invention may further include a dilator handle and a locking collar. The dilator handle is configured for directing movement of the dilator relative to the sheath and has a body portion with a proximal portion including a receiving port in communication with the dilator and a distal portion including a tapered stem. The locking collar includes an axial bore therethrough, a proximal portion including an first seating engagement configured for rotatably mounting the tapered stem of the dilator handle therein and a distal portion including a second selectively lockable engagement configured for alternately securing and unsecuring the locking collar with the proximal end portion of the sheath. By securing the locking collar with the sheath, axial movement of the dilator relative to the sheath is restricted.  
           [0016]    Preferably, the second selectively lockable engagement on the distal portion of the locking collar includes cooperative interlocking structures defined on the proximal end portion of the sheath and on an inner wall of the locking collar. These cooperative interlocking structures are engaged and disengaged by rotational movement of the locking collar relative to the proximal end portion of the sheath. Furthermore, it is preferable that the movement of the selectively adjustable annular seal between the open position and closed position is actuated by the engagement and disengagment of the locking collar with the proximal end portion of the sheath.  
           [0017]    The present invention is also directed to a vascular introducer having an adjustable hemostatic seal. This embodiment of the present invention includes an elongate hollow sheath defining an axial lumen which has opposed proximal and distal end portions; a hub operatively associated with the proximal end portion of the sheath which includes a hub body portion with an axial bore in fluid communication with the axial lumen of the sheath, and a tapered proximal portion having a helical thread defined along an outer periphery thereof and a recessed channel defined circumferentially along an inner periphery thereof; an elastic annular seal disposed within the recessed channel of the hub; and a cap having an axial bore extending therethrough with a helical thread for cooperating with the helical thread of the tapered proximal portion of the hub so that rotational movement of the cap relative to the hub causes the annular seal to move radially relative to the axial bore of the hub.  
           [0018]    This embodiment of a vascular introducer constructed in accordance with the present invention may be configured so that the radial movement of the annular seal, which may be fabricated of an elastomeric material such as silicone, is actuated by axial rotation of the cap about a 90 degree arc. Preferably, the aforementioned vascular introducer of the present invention also includes handle members protruding radially from the hub body portion.  
           [0019]    In a preferred embodiment of the vascular introducer of the present invention, a trocar seal is disposed about the axial bore of the cap to prevent fluid flow from the lumen and permit insertion of devices through the axial bore of the cap.  
           [0020]    The present invention is also directed to a vascular introducer which includes an elongated dilator having a tapered distal end portion and an axial passage extending therethrough; an elongated hollow sheath having opposed proximal and distal end portions and an axial lumen extending therethrough to accommodate the dilator; a hub operatively associated with the proximal end portion of the sheath which includes a hub body portion with an axial passage for accommodating the dilator and being in fluid communication with the axial lumen of the sheath, and a tapered proximal portion; a dilator handle associated with a proximal end of the dilator including a proximal receiving port in communication with the axial passage of the dilator and a distal mounting stem; and a locking collar having an axial bore with a proximal portion configured to receive the distal mounting stem of the dilator handle to facilitate rotation of the dilator handle and a distal portion configured to engage the tapered proximal portion of the hub.  
           [0021]    The aforementioned embodiment of a vascular introducer constructed in accordance with the present invention can include cooperative interlocking structures defined on the distal portion of the locking collar and the tapered proximal portion of the hub. Preferably, these cooperative interlocking structures are configured to be engaged by rotational movement of the locking collar relative to the hub about a 90 degree arc through an axial plane. In one embodiment, the cooperative interlocking structures include a pair of pins radially projecting from the tapered proximal portion of the hub and a corresponding pair of receiving slots for the pins defined in an interior wall of the locking collar.  
           [0022]    The aforementioned vascular introducer may also include the selectively adjustable annular seal operatively associated with the proximal end portion of the hub and configured for movement of the axial passage between an open position in which the passage of instruments through the axial lumen is unrestricted and a closed position in which insertion of an instrument through the axial lumen is restricted as described above. Preferably, the vascular introducer is configured such that the engagement of the distal portion of the locking collar with the tapered proximal portion of the hub moves the axial passage to the closed position. Even more preferably, the adjustable seal and the cooperative interlocking structures are alternatively engaged and disengaged by rotational movement of the locking collar about a 90 degree arc in the axial plane.  
           [0023]    In one embodiment of the present invention, the selectively adjustable annular seal includes a threaded portion defined on the tapered proximal portion of the hub; a circumferential recessed channel defined in an interior wall of the tapered proximal portion of the hub; an annular compressible sealing ring disposed in the circumferential recessed channel of the hub; and a sealing cap having an axial bore and a threaded portion defined therein for being threadably engaged with the threaded portion defined on the tapered proximal portion of the hub, wherein the annular compressible sealing ring in the circumferential recessed channel of the tapered proximal portion of the hub is selectively moved from a compressed position in which fluid egress through the axial passage is restricted and a decompressed position in which fluid egress through the axial passage is unrestricted by alternate threadable engagement of the sealing cap. Preferably, the sealing cap is seated within the axial bore of the locking collar such that alternate rotational movement of the locking collar effectuates the threaded engagement and disengagement of the sealing cap with the tapered proximal portion of the hub.  
           [0024]    Further features of the vascular introducer of the subject invention will become more apparent from the detailed description of the present invention that follows taken in conjunction with the drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    So that those having ordinary skill in the art to which the present application appertains will more readily understand how to make and use the same, reference may be had to the drawings wherein:  
         [0026]    [0026]FIG. 1 is a perspective view of a vascular introducer assembly constructed in accordance with a preferred embodiment of the subject invention in a fully assembled condition;  
         [0027]    [0027]FIG. 2 is an exploded perspective view of the vascular introducer assembly of FIG. 1 with parts separated for ease of illustration;  
         [0028]    [0028]FIG. 3 is an enlarged cross sectional view of the hub portion of the vascular introducer assembly of FIG. 1;  
         [0029]    [0029]FIG. 4 is an enlarged cross sectional view of the proximal portion of the vascular introducer assembly of FIG. 1 with the rotatable locking collar in a locked position to prevent axial movement of the dilator relative to the sheath and the hemostatic seal in a closed position which restricts access through the axial lumen of the sheath;  
         [0030]    [0030]FIG. 5 is a perspective view of the vascular introducer assembly of FIG. 1 being percutaneously introduced into a blood vessel along a guidewire;  
         [0031]    [0031]FIG. 6 is a perspective view of the proximal portion of the vascular introducer of FIG. 1 illustrating the rotational movement of the locking collar which moves the hemostatic seal to an open position in which passage of instruments through the axial lumen of the sheath is unrestricted;  
         [0032]    [0032]FIG. 7 is a perspective view of the vascular introducer of FIG. 1 illustrating the manner in which the rotatable locking collar and dilator are separated from the sheath and also showing the hemostastic seal which remains intact on the hub portion of the introducer;  
         [0033]    [0033]FIG. 8 is a cross sectional view of the hub portion and sealing cap of the vascular introducer assembly of FIG. 1 after the rotatable locking collar and dilator have been removed therefrom to illustrate the components of the present invention forming the adjustable hemostatic seal, with the seal being disposed in an open position in which passage of instruments through the axial lumen of the sheath is unrestricted;  
         [0034]    [0034]FIG. 9 is a cross sectional view of the hub portion and sealing cap as shown in FIG. 1, which illustrates the valve in an open position with an endocardial lead being inserted through the trocar seal of the sealing cap;  
         [0035]    [0035]FIG. 10 is a cross sectional view of the hub portion and sealing cap shown in FIG. 9, along with the dilator disposed in the lumen of the introducer assembly, illustrating the movement of the sealing cap relative to the hub so that the hemostatic seal radially compresses around the dilator;  
         [0036]    [0036]FIG. 11 is a cross sectional view of the hub portion of FIG. 10 illustrating the manner in which the sealing cap is removed from the hub when the hemostatic seal is in an open position; and  
         [0037]    [0037]FIG. 12 is a perspective view of the vascular assembly of the subject invention illustrating the manner in which the sheath is split along score lines to facilitate removal from the operative site.  
     
    
       [0038]    These and other features of the vascular introducer assembly of the subject invention will become more readily apparent to those having ordinary skill in the art from the following description of the preferred embodiment.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0039]    In the following detailed description of the present invention, references are made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and equivalents thereof.  
         [0040]    Referring now to the drawings wherein like reference numerals identify similar structural features of the invention, there is illustrated in FIG. 1, a vascular introducer assembly constructed in accordance with a preferred embodiment of the subject invention and designated generally by reference numeral  10 . Vascular introducer assembly  10  generally includes an elongated tubular body  12 . The general shape and orientation of assembly  10  as shown in FIG. 1 defines a longitudinal axis and an axially opposed distal end  14  and proximal end  16  relative thereto, and these designations will be used as a convention throughout the following description to describe the components and features of the present invention.  
         [0041]    Referring now to both FIGS. 1 and 2, this embodiment of introducer assembly  10  has a body  12  that generally includes (listed in order from distal end  14  to proximal end  16 ) an outer sheath  18 , an engagement hub  20 , a sealing cap  22 , a locking collar  24  and a dilator handle  26 , each of which are disposed over a hollow elongate dilator  28  and will be discussed in further detail herein below.  
         [0042]    Beginning with the distal-most component of assembly  10 , outer sheath  18  is hollow and elongate. As shown in FIGS. 3 and 4, outer sheath  18  defines an interior axial lumen  30  for, among other things, accommodating dilator  28 . As illustrated in this embodiment, dilator  28  includes a curved distal end portion  32 , which, among other things, facilitates endocardial lead placement into areas of the heart that are difficult to access by intravascular means, such as the coronary sinus, but may also be straight or shaped in some other manner as well. Sheath  18  is preferably constructed of a compliant and flexible but resilient material that permits it to assume a curved form corresponding to the curvature of distal end portion  32 . Preferably, sheath  18  is fabricated so that its shape may vary depending upon the intended use of the introducer.  
         [0043]    Referring now to FIG. 3, along with continuing reference to FIGS. 1 and 2, engagement hub  20  generally includes a central body portion  34  having a tapered distal end portion  36 , a sheath handle  38 , a tapered proximal end portion  40  and an axial bore  42  therethrough in fluid communication with axial lumen  30 . Tapered proximal end portion is sloped inwardly at an angle a, which is preferably between about 1 and about 8 degrees relative to the longitudinal axis defined by introducer  10 . In this embodiment, sheath handle  38  includes a pair of opposing, radially outward projecting portions  38   a  and  38   b . Preferably, the axial bore  42  is substantially aligned with and about the same diameter as axial lumen  30 .  
         [0044]    Proximal end portion  40  is fabricated of a flexible yet resilient material and includes a pair of opposed, radially outward projecting pins  44  positioned distally relative to a threaded portion  46  defined on the exterior of the proximal end portion  40 , which is tapered as mentioned above so that its outer diameter generally decreases axially in the proximal direction. A circumferential channel  48  for receiving an annular sealing ring  50  therein is defined along the interior wall of proximal end portion  40  adjacent to its proximal end. Preferably, annular sealing ring  50  is fabricated from a flexible yet resilient material such as silicone. In this embodiment, annular sealing ring  50  includes a pair of semi-circular portions  50   a  and  50   b.    
         [0045]    Sealing cap  22  includes a body  52  having axially defined, substantially parallel grooves or flutes defined on its exterior and an axial bore  54  with a threaded portion  56  configured to engage the threaded portion  46  defined on the exterior of proximal end portion  40  of hub  20 . Preferably, and as shown with specificity in FIG. 2, cap  22  further includes a trocar seal  58  disposed over axial bore  54  at the proximal end of cap  22 . Trocar seal  58  generally consists of a flexible but resilient material having three slits  60  defined therein which extend radially outward from its center to form three flaps. The three flaps may be forcibly opened to receive the dilator or other device while impeding fluid egress from the sealing cap  22 .  
         [0046]    Locking collar  24  includes a central body  62  having a single, radially outward projecting L-shaped handle  64  an axial bore  66  for receiving sealing cap  22 . In this embodiment, axial bore  66  includes axially defined, substantially parallel grooves or flutes  67  for interlocking with the exterior sealing cap  22  so that rotational movement of collar  24  (i.e., movement not in the axial direction) results in the rotational movement of sealing cap  22  in accordance therewith. Collar  24  also includes a pair of slots  68  that are recessed in the interior wall of body  62  which defines axial bore  66  adjacent to the distal end of collar  24 . Slots  68  are configured and dimensioned to receive pins  44  of hub  20  and cooperate together to secure locking collar  24  with the proximal end portion  40  of hub  20 . Slots  68  each include an axial portion  70  which extends in the proximal direction along the interior of collar  24  and is joined with a circumferential portion  72  that extends circumferentially along the interior periphery of collar  24 . Collar  24  further includes a circular rim  74  defined at the proximal end of central body  56 .  
         [0047]    Dilator handle  26  includes a tapered distal stem portion  76 , a single, radially outward projecting handle  78 , a proximal receiving port  80  and an axial bore  82  therein.  
         [0048]    Tapered distal stem portion  76  includes a ridge  84  for engaging the circular rim  74  at the proximal end of collar  24  so that dilator handle  26  is rotatably mounted in the proximal end of collar  24 . Axial bore  82  is in fluid communication with dilator  28  and proximal receiving port  80 , thus, objects or devices such as endocardial leads may be inserted into dilator  28  via proximal receiving port  80 .  
         [0049]    In use, the dilator  28  in vascular introducer assembly  10  is inserted over a guidewire  86 , as shown in FIG. 5 and as described in the above background section. An arrow  88  is defined radially along the projecting handle  78  of dilator handle  26  to identify the relative direction of the curvature in distal end portion  32  of dilator  28 . The locking collar  24 , dilator handle  26  and sealing cap  22  cooperate to generally define a rotatable sheath lock and hemostatic seal. As illustrated in FIG. 5, collar  24  is in the locked position on pins  44  (not shown in FIG. 5), which increases the rigidity and stability of the introducer assembly  10  for intravenous insertion, among other things.  
         [0050]    As previously noted, rotational movement of collar  24  simultaneously causes the rotation of sealing cap  22 , which is interlocked with collar  24  by flutes  67  in axial bore  66 . As shown in FIG. 4, placing collar  24  in the locked position (i.e., pins  44  engaged within the circumferential portion  72  of slots  68 ) rotates sealing cap  22  in the clockwise direction on threaded portion  46  of the tapered proximal end portion  40  of hub  20 . By twisting sealing cap  22  clockwise, cap  22  also moves distally with respect to proximal end portion  40 , which causes a crimping action that forces proximal end portion  40  radially inward. This action reduces the diameter of axial bore  42  so that the annular sealing ring  50  at the proximal end of axial bore  42  closes around dilator  28 , thus, impeding fluid (i.e., blood) flow entering via the distal end of lumen  30  from exiting through bore  42  and restricting insertion of devices into lumen  30 .  
         [0051]    Referring now to FIGS. 6 and 7, rotating collar  24  counterclockwise, so that outwardly projecting handle  64  of collar  26  is adjacent handle  78  on dilator handle  26 , unlocks pins  44  from slots  68 . Sealing cap  22  is also rotated counterclockwise which causes the movement of cap  22  along threaded portion  46  in the proximal direction which releases the aforementioned crimping action. Thus, fluid flow through axial bore  42  is no longer impeded by sealing ring  50 . Preferably, the circumferential portions  72  of slots  68  in collar  24  are sufficiently elongated so that collar  24  can be fastened onto pins  44 , or unfastened therefrom, by rotating the collar  24  about 90 degrees in either direction.  
         [0052]    As shown in FIG. 7, rotating collar  24  to unlock collar  24  from pins  44  in hub  20  allows the collar, along with dilator handle  26  and dilator  28 , to move axially and be disengaged from the remaining components (i.e., sealing cap  22 , hub  20  and outer sheath  18 ) in this embodiment of introducer assembly  10 .  
         [0053]    As shown in FIGS. 8 and 9, trocar seal  58  inhibits fluid flow entering lumen  30  from exiting cap  22  when collar  24 , dilator handle  26  and dilator  28  are removed from introducer assembly  10 . This allows guidewire  86  to be removed so that introducer assembly  10  may be used to insert devices or equipment, such as an endocardial lead  90 , intravenously through lumen  30 . In addition, dilator  28  and other associated components may be reinserted through lumen  30 , and cap  22  may be threaded onto threaded portion  46  thereafter so that the aforementioned crimping action is applied, as shown in FIG. 10.  
         [0054]    As illustrated in FIG. 11, cap  22  may be threaded off and removed from hub  20 . As described in the background section, this is essentially the first step in the removal of the introducer assembly  10 , and facilitates removal of outer sheath  18  and hub  20 . As shown in FIG. 12, in this embodiment, outer sheath  18  and hub  20  can be split substantially in half by pulling both handles  38   a  and  38   b  of hub  20  apart in opposing radial directions. Handle  38   a  is marked with an arrow  92  pointing in the radial direction as a guide. Preferably, outer sheath  18  and hub  20  are constructed with axially opposing weakened zones or score lines that facilitate dividing sheath  18  as shown in FIG. 12, without compromising the integrity of sheath  18  or restricting use of sheath  18  for any of its intended purposes.  
         [0055]    While the invention has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that various changes and/or modifications can be made to the invention with departing from the spirit or scope of the invention.
A vascular introducer assembly is disclosed that includes a dilator, a sheath having an axial lumen for accommodating the dilator, a locking collar for securing the dilator and the sheath to one another and an adjustable hemostatic seal for preventing fluid egress from the axial lumen and restricting insertion of instruments through the axial lumen.