Passive hemostatic sheath valve

The present invention provides vascular introducer sheaths incorporating improved passive valves which can maintain hemostasis around medical instruments. A passive sheath valve for creating a hemostatic seal around a medical instrument comprises a valve body having an upstream end, a downstream end, and a lumen having an inner and outer surface therethrough. The valve body defines a sealing aperture that is configured nominally to remain open. The upstream end includes an upstream annulus region defining at least one opening and the downstream end includes a downstream annulus region. Each annulus region and lumen outer surface define at least one chamber. The at least one opening transmits pressure from the upstream end through the upstream annulus region so as to allow a fluid to enter the at least one chamber.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally related to medical devices and methods. More particularly, the present invention relates to vascular introducer sheaths incorporating improved passive valves that can maintain hemostasis around medical instruments.

Vascular introducer sheaths are well known components of vascular access systems that are used in a wide variety of diagnostic and therapeutic vascular procedures. For example, introducer sheaths are used in a number of minimally invasive procedures such as endovascular procedures and laparoscopic surgery. Of specific interest relative to the present invention is the endovascular placement of grafts, stents, stent-grafts, and other endoluminal prostheses. Such procedures are often performed through vascular access systems that include an introducer sheath to provide access to a body lumen (e.g., blood vessels), cavity, or organ. A sealing valve typically is located at a proximal portion of the introducer sheath. When medical instruments or tools are inserted into or withdrawn from the sealing valve, the valve generally prevents fluid from inadvertently leaving (e.g., back bleeding) or entering the body lumen through the introducer sheath.

Current introducer sheath valves generally fall into two basic categories: passive and active. A passive valve generally relies on the deformation of a resilient sealing body by the medical instrument inserted through the valve to form the desired fluid tight seal. Active medical valves include a mechanism that moves a sealing body into contact with the traversing medical instrument.

A wide variety of passive and active sealing valve structures for use with introducer sheaths have been proposed. These structures provide different hemostatic valve designs that typically vary in terms of the valve shape, aperture or slit geometry, aperture or slit position, and other design aspects. While these structures have met with varying degrees of success and acceptance, they generally still suffer from disadvantages of leakage around the sealing valve.

For these and other reasons, it is desirable to provide improved introducer sheath hemostatic valves for use in endovascular, laparoscopic, and other medical procedures. It would be particularly desirable if these improved valves provide enhanced hemostasis sealing (i.e., preventing leakage of fluid from or into the introducer sheath), maximize safety, and do not require any actuation in the various modes of operation. It would be further desirable if these improved valve structures were better adapted for passing instruments both distally and proximally therethrough as well as for providing a fluid-tight seal across a wide range of medical instrument diameters.

2. Description of the Background Art

The full disclosures of each of the above references are incorporated herein by reference.

BRIEF SUMMARY OF THE INVENTION

The present invention provides vascular introducer sheaths incorporating improved passive valves which can maintain hemostasis around medical instruments. In particular, the hemostatic valves of the present invention provide secure and reliable sealing so at to minimize leakage of fluid from (e.g., back bleeding) or into the introducer sheath when various instruments or tools are inserted into or withdrawn through the sealing valve. Further, these hemostatic valves provide easy loading of instruments both distally and proximally therethrough, a fluid-tight seal across a wide range of medical instrument diameters, and do not require any actuation mechanisms for sealing.

In one aspect of the present invention, a passive valve for creating a hemostatic seal around a medical instrument is provided. The valve is configured to be removably housed within an introducer sheath. The valve comprises a valve body having an upstream end, a downstream end, and a lumen having an inner and outer surface therethrough. The valve body defines a sealing aperture or hole that is configured nominally to remain open. The upstream end includes an upstream annulus region defining at least one opening and the downstream end includes a downstream annulus region. Each annulus region and lumen outer surface define at least one chamber. The at least one opening transmits pressure from the upstream end through the upstream annulus region so as to allow a fluid (e.g., blood) to enter the at least one chamber as a greater pressure is generally on the upstream side.

The opening advantageously allows for pressure equalization on the upstream and downstream ends of the valve body so that the valve body is less likely to inflate and leak fluids from or into the introducer sheath when medical tools (e.g., guidewires, catheters, snares, balloons, or other interventional instruments) are inserted into or withdrawn from the sealing valve. Moreover, filling of the chamber via the opening enhances the fluid tight hemostatic seal around the medical instrument. The sealing aperture facilitates easy loading of instruments both distally and proximally. The term “opening” as used herein is defined to include a slit, slot, hole, aperture, access, passage, or like opening which facilitates fluid flow into the chamber so as to maintain the integrity of the valve while preventing pressure build up on either ends of the valve. It will therefore be appreciated that the at least one opening may take on a variety of shapes, sizes, number, dimensions, and/or configurations from those described herein. In one exemplary embodiment of the present invention, the upstream annulus region defines four equally spaced pressure equalization slots having slot widths in a range from about 0.030 inch or less to about 0.075 inch or greater, as for example 0.045 inch, although any shape (e.g., circular shape, S-shape, diamond shape, etc.), number (e.g., one, two, three, four, five, six, etc.), and/or configuration (e.g., irregularly or symmetrically spaced) of openings may be utilized.

The sealing aperture comprises a variable orifice for sealing around a wide range of medical instrument diameters. The variable orifice typically has a nominal diameter (e.g., diameter without any instrument passing therethrough) in a range from about 0.015 inch or less to about 0.220 inch or greater, as for example 0.030 inch. Other useful ranges for the orifice nominal diameter include from about 0.020 inch to about 0.220 inch, from about 0.015 inch to about 0.050 inch, from about 0.025 inch to about 0.035 inch, and from about 0.0275 inch to about 0.0325 inch. The sealing aperture provides an expansion coefficient in a range from about 500% to about 1200% or higher of the nominal diameter; more particularly from about 500% to about 700% of the nominal diameter. The variable orifice may be expansible from a first reduced diameter when no medical instrument traverses the sealing aperture (e.g., before or after instrument insertion) to a second enlarged diameter when the medical instrument traverses the sealing aperture (e.g., during instrument insertion, placement or withdrawal). The variable orifice may be capable of sealingly receiving therethrough one or more instruments having a diameter ranging from about the same or slightly larger diameter as the nominal diameter of the aperture to about twelve or more times the nominal diameter of the aperture.

In one embodiment of the present invention, the lumen may comprise an hourglass configuration having a funnel-shaped upstream lumen that converges inwardly and a funnel-shaped downstream lumen that diverges outwardly. The upstream and downstream lumens intersect at the sealing aperture. This hourglass configuration has many advantages. For example, when a medical instrument is being withdrawn through the aperture, the funnel shape of the upstream lumen reduces the possibility that any sharp edges present on the instrument will damage the valve body, thus improving the likelihood that the sealing aperture will provide a desirable fluid-tight seal around the instrument. Further, this hour glass shape has been found to help maintain the shape of the passive valve, particularly at the sealing aperture. Still further, this hour glass configuration promotes pressure normalization on either ends of the valve so as to minimize wear, tear, or further damage of the valve. It will be appreciated that the funnel-shaped upstream and downstream lumens may be symmetric or non-symmetric (e.g., different lead-in angles, length, etc.) as desired. In another embodiment of the present invention, the lumen comprises a conical configuration having a funnel-shaped downstream lumen, wherein the sealing aperture is positioned adjacent the upstream annulus region.

The valve embodiments of the present invention may generally be formed from silicone, rubber, a combination thereof, or like medical device grade materials that can accommodate a variety of medical instrument diameters without plastic deformation or tearing. A useful material for the valve body of the present invention comprises 40 or 50 durometer silicone rubber. The medical instrument may comprise a guidewire, catheter, or like device.

The present invention may further comprise at least one reinforcing rib extending, for example, from the valve upstream annulus region to the valve downstream annulus region. Such reinforcing ribs or like reinforcements help to maintain the axial integrity of the variable orifice. In some embodiments, a valve cartridge may further be disposed between the valve upstream annulus region and the valve downstream annulus region. The valve cartridge further inhibits leakage of fluid from or into the introducer sheath by forming an additional seal between the annulus regions. The valve cartridge may comprise any biocompatible polymer (such as polycarbonate or nylon) or like materials and may be mechanically fastened, welded, or otherwise affixed into place.

In another aspect of the present invention, a passive valve for creating a hemostatic seal around a medical instrument is provided. The valve is configured to be removably housed within an introducer sheath. The valve comprises a valve body having an upstream end and a downstream end. The valve body defines a lumen having inner and outer surfaces therethrough. The lumen may comprise an hourglass configuration having a funnel-shaped upstream lumen that converges inwardly and a funnel-shaped downstream lumen that diverges outwardly. The upstream and downstream lumens intersect at a sealing aperture configured nominally to remain open, even when no instrument traverses the valve aperture. The upstream end includes an upstream annulus region defining at least one slot or slit and the downstream end includes a downstream annulus region. Each annulus region and lumen outer surface defines at least one chamber. The at least one slot or slit transmits pressure from the upstream end through the upstream annulus region.

In a further aspect of the present invention, yet another passive valve for creating a hemostatic seal around a medical instrument is provided. The valve is removably housed within an introducer sheath. The valve comprises a valve body having an upstream end and a downstream end. The valve body defines a lumen having an inner and outer surface therethrough. The lumen comprises a conical configuration having a funnel-shaped downstream lumen. The upstream end includes an upstream annulus region defining at least one slot or slit, wherein a sealing aperture is positioned between the upstream annulus region and the downstream lumen. The downstream end includes a downstream annulus region. Each annulus region and lumen outer surface defines at least one chamber. The at least one slot or slit transmits pressure from the upstream end through the upstream annulus region.

In yet another aspect of the present invention, a bifurcated medical introducer sheath is provided comprising a tubular shaft having two proximal ends and one distal end (e.g., Y-shaped configuration). Two hemostasis valves are removably positioned within each of the proximal ends of the tubular shaft and two valve cartridges are removably positioned within each proximal end of the tubular shaft. This proximal dual valve Y-shaped hub advantageously allows for multiple instruments (e.g., two or more) to be inserted, placed, and/or withdrawn within the one unitary structure while preventing fluid leakage.

The bifurcated sheath may incorporate a variety of hemostasis valves. For example, at least one valve may comprise a passive hemostatic valve having a valve body including an upstream end and a downstream end. The valve body defines a lumen having an inner and outer surface therethrough and a sealing aperture configured nominally to remain open. The upstream end includes an upstream annulus region defining at least one slot or slit and the downstream end includes a downstream annulus region. Each annulus region and lumen outer surface defines at least one chamber. The at least one slot or slit transmits pressure from the upstream end through the upstream annulus region so as to allow a fluid to enter the at least one chamber to equalize pressure on the upstream and downstream ends of the valve body and to enhance a hemostatic seal around an instrument. In such an embodiment, at least one valve cartridge may be disposed between the upstream annulus region and the downstream annulus region. Typically, each annulus region of the valve engages an inner lumen of the tubular body. The sealing aperture of the valve comprises a variable orifice which is expansible from a first reduced diameter to a second enlarged diameter and which has a nominal diameter range from about 0.020 inch to about 0.220 inch.

Alternatively, the bifurcated sheath may incorporate any conventional duckbill valve to be removably received within one end (or both ends) of the bifurcated sheath to prevent any fluid leakage from or into the shaft when no instrument is traversing the valve. Still further, the bifurcated sheath may incorporate any conventional hemostatic valve to be removably received within one end (or both ends) of the bifurcated sheath. For example, conventional hemostasis valves are commercially available from Thomas Medical Products, Inc. of Malvern, Pa. It will be appreciated that any number of valve permutations may be incorporated within the bifurcated sheath. For example, the bifurcated sheath may incorporate two of the passive hemostatic valves described above, one passive hemostatic valve and one conventional valve (e.g., duckbill valve), or two conventional valves.

In a further aspect of the present invention, methods for creating a hemostatic seal around a medical instrument are provided. One method comprises providing a passive valve removably housed within an introducer sheath. The valve includes a valve body having an upstream end and a downstream end. The valve body defines a lumen having an inner and outer surface therethrough. The lumen comprises an hourglass configuration having a funnel-shaped upstream lumen that converges inwardly and a funnel-shaped downstream lumen that diverges outwardly. The upstream and downstream lumens intersect at a sealing aperture configured nominally to remain open. The upstream end includes an upstream annulus region having at least one slot or slit and the downstream end includes a downstream annulus region. Each annulus region and lumen outer surface define at least one chamber. As the instrument traverses the valve, the at least one slot or slit transmits pressure from the upstream end through the upstream annulus region so as to allow a fluid to enter the at least one chamber to equalize pressure on the upstream and downstream ends of the valve body and to enhance the hemostatic seal around the instrument.

In still a further aspect of the present invention, a method for assembling a medical device is provided. An introducer sheath is provided within which a passive valve is housed. The valve includes a valve body having an upstream end and a downstream end. The valve body defines a lumen having an inner and outer surface therethrough. The lumen comprises an hourglass configuration having a funnel-shaped upstream lumen that converges inwardly and a funnel-shaped downstream lumen that diverges outwardly. The upstream and downstream lumens intersect at a sealing aperture configured nominally to remain open. The upstream end includes an upstream annulus region having at least one slot or slit and the downstream end includes a downstream annulus region. Each annulus region and lumen outer surface defines at least one chamber. A medical instrument is further provided for positioning through the valve. The at least one slot or slit transmits pressure from the upstream end through the upstream annulus region so as to allow a fluid to enter the at least one chamber to equalize pressure on the upstream and downstream ends of the valve body and to enhance the hemostatic seal around the instrument.

A further understanding of the nature and advantages of the present invention will become apparent by reference to the remaining portions of the specification and drawings.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides vascular introducer sheaths incorporating improved hemostatic passive valves for use in endovascular, laparoscopic, and other medical procedures. Vascular sheaths generally provide access to a body lumen (e.g., a blood vessel), cavity, or organ for the delivery of medical instruments, such as guidewires, catheters, etc. that may further contain devices such as stents, stent-grafts, balloons, etc. The hemostatic valve may be releasable from the introducer sheath or be an integral part of the introducer sheath. The hemostatic valves may further be incorporated into any portion of the sheath (e.g., hub or shaft), at a common position or at a different position. The hemostatic valves of the present invention provide secure and reliable sealing so as to minimize leakage of fluid from (e.g., back bleeding) or into the introducer sheath when medical instruments or tools are inserted into or withdrawn from the sealing valve. Further, the valves of the present invention are adapted to seal about a wide variety of medical instruments having a wide range of instrument diameters. It will be appreciated that the hemostatic valves of the present invention may also be incorporated into a number of different of medical devices, such as bifurcated sheaths, catheters, cannulas, trocar assemblies, and other tubular medical devices, and are not limited to incorporation with an introducer sheath.

Referring now toFIGS. 1A and 1B, an exemplary introducer sheath10with which various embodiments of the present invention may be used is illustrated. The introducer sheath10generally comprises a tubular shaft12having a proximal end13and a distal end15and a two-piece hub14that is adapted for coupling to the proximal end13of shaft12. Hub14comprises hub main body14A and cap14B which may be coupled to one another by any appropriate means, such as by threading or, as shown inFIGS. 1A and 1B, by being press fit or mechanically snapped into place. The sheath10may be formed from a variety of medical grade materials. Particularly useful for the present invention is a composite sheath comprising an inner liner, a braid, and an outer layer. The inner liner is made of biocompatible lubricious polymers such as fluoropolymers (e.g., polytetrafluoroethylene or PTFE), fluorinated ethylene propylene (FEP), or high density polyethylene. The liner may also be filled with a radiopaque material such as barium sulfate or the like. The braid may be any number of materials such as stainless steel, etc. and may be in a ribbon form. The outer layer is made of a bondable polymer such as nylon or fluoropolymers such as PEBAX®. Other sheath materials and configurations may be used.

As shown inFIG. 1B, a passive hemostatic valve16as described in more detail below may removably be positioned at a proximal portion13of the introducer sheath10within the hub14. As noted above, the valve16may alternatively be integrally formed within the sheath10and positioned at any desired portion of the sheath10. As shown inFIGS. 1B,4B and4C, a valve cartridge18may also be removably positioned integral with valve16as will be described in more detail below. The valve cartridge18may be formed from a variety of biocompatible materials including polymers (such as polycarbonate or nylon) and is removably positioned into place. It will be appreciated that the above depictions are for illustrative purposes only and do not necessarily reflect the actual shape, size, or dimensions of the sheath10, valve16, or cartridge18. For example, the shaft12has a greater length than illustrated inFIGS. 1A and 1B. This applies to all depictions herein.

Referring now toFIGS. 2A through 2F, a passive hemostatic sheath valve16in accordance with one embodiment of the present invention is illustrated. The valve16for creating a hemostatic seal around a medical instrument comprises a valve body20having an upstream end22and a downstream end24. The valve body20defines a lumen26having an inner surface28and an outer surface30therethrough. The lumen26comprises an hourglass configuration having a funnel-or conical-shaped upstream lumen32that converges inwardly and a funnel-shaped downstream lumen34that diverges outwardly. The upstream and downstream lumens32,34intersect at a sealing aperture or hole36configured nominally to remain open (i.e., prior to, during, and subsequent to device insertion). The upstream end22includes an upstream annulus region38defining at least one opening40and the downstream end24includes a downstream annulus region42.

As shown inFIG. 2B, the valve16of this embodiment includes four openings40within the upstream end22that are symmetrically spaced so as to promote equal stress distribution within the valve body. However, it will be appreciated that any number of openings40may be utilized (e.g., from two to six or more) on either end22,24of the valve body20to achieve the desired pressure equalization, in any configuration, shape, and/or size, as described herein. The circular shaped holes40of this embodiments will have a diameter in a range from about 0.005 inch to about 0.080 inch; more particularly from about 0.030 inch to about 0.055 inch.

As shown in the view ofFIG. 2D, the sealing aperture36comprises an orifice capable of accommodating and providing a fluid-tight seal around a wide range of medical instrument diameters. The variable orifice typically has a nominal diameter (e.g., diameter without any instrument passing therethrough) in a range from about 0.015 inch to about 0.220 inch, as for example 0.030 inch. Other useful ranges for the orifice nominal diameter include from about 0.020 inch to about 0.220 inch, from about 0.015 inch to about 0.050 inch, from about 0.025 inch to about 0.035 inch, and from about 0.0275 inch to about 0.0325 inch. The sealing aperture provides an expansion coefficient in a range from about 500% to about 1200% or higher of the nominal diameter; more particularly from about 500% to about 700% of the nominal diameter. The variable orifice may be expansible from a first reduced diameter when no medical instrument traverses the sealing aperture (e.g., before or after instrument insertion) to a second enlarged diameter when the medical instrument traverses the sealing aperture (e.g., during instrument insertion, placement or withdrawal).

Referring now toFIGS. 3A through 3F, a passive hemostatic sheath valve16in accordance with another embodiment of the present invention is illustrated. The passive valve16for creating a hemostatic seal around a medical instrument comprises a valve body20having an upstream end22and a downstream end24. The valve body20defines a lumen44having an inner surface46and an outer surface48therethrough. The lumen44comprises a conical or funnel configuration having a funnel-shaped downstream lumen50. The upstream end22includes an upstream annulus region38defining at least one opening40, wherein a sealing aperture36is positioned between the upstream annulus region38and the downstream lumen50. The downstream end24includes a downstream annulus region42.

As shown inFIGS. 3E,3F,2E, and2F, the valves16of the present invention may further comprise at least one reinforcing rib52extending from the upstream annulus region38to the downstream annulus region42. The valve16comprises four reinforcing ribs52, however, it will be appreciated that any desired number of reinforcing ribs52may be utilized (e.g., two to six or more). Such reinforcing ribs52or the like help maintain the axial integrity of orifice36. The valve embodiments16of the present invention are generally formed from silicone, rubber, a combination thereof, or like medical device grade materials that can accommodate a variety of medical instrument diameters without plastic deformation or tearing. A useful material of the valve body20comprises40or50durometer silicone rubber.

Referring now toFIGS. 4A through 4C, views of an introducer sheath10housing the passive hemostatic sheath valve16ofFIGS. 2A-2Fare illustrated. As can be seen in the cross sectional views ofFIGS. 4B and 4C, each annulus region38,42and lumen outer surface30define a chamber54. The openings40transmit pressure from the upstream end22via the upstream annulus region38so as to allow a fluid (e.g., blood or air) to enter the chamber54as a greater pressure is generally on the upstream side22. Pressure from the fluid entering the chamber54symmetrically seals the walls of aperture36around the instrument. Hence, the opening40advantageously allows for pressure equalization on the upstream22and downstream24ends of the valve body20so that the valve body is less likely to inflate and leak fluids from or into the introducer sheath10when medical tools are inserted into or withdrawn from the sealing aperture36. In this illustration, the valve cartridge18is disposed between the upstream annulus region38and the downstream annulus region42and within the hub14so as to form a boundary of the chamber54. As such, the cartridge18further helps create a seal around the aperture36that inhibits leakage of fluid from or into the introducer sheath10, particularly in the case of instruments having a diameter which is the same or nearly the same as the orifice nominal diameter. In particular, the valve cartridge18helps maintain the integrity of orifice36by redistributing forces away from the aperture so that it remains intact. It will be appreciated that the hub14may also form a boundary of the chamber54in the absence of a valve cartridge18.

Referring now toFIGS. 5A through 5C, cross-sectional views of an exemplary method for creating a hemostatic seal around a medical instrument56are illustrated. This method comprises providing a passive valve16as previously described above in detail. For purposes of illustration only, the valve embodiment ofFIGS. 2A through 2Fare shown, although the valve embodiment ofFIGS. 3A through 3Fmay be used as well. As the instrument56traverses the valve16, as seen inFIG. 5B, the at least one opening40transmits pressure from the upstream end22through the upstream annulus region38so as to allow a fluid to enter the chamber54(FIGS. 4B and 4C) to equalize pressure on the upstream22and downstream24ends of the valve body20and to enhance the hemostatic seal around the instrument56. The variable orifice36may be capable of sealingly receiving therethrough one or more instruments56having a diameter ranging from about0.005inch greater than the nominal diameter of orifice36(FIGS. 5Aand SC) to about eight or more times the nominal diameter of the orifice (FIG. 5B). A hemostatic seal may be achieved even when instrument56diameter is the same or nearly the same as the nominal diameter of orifice36. It is believed that the design features of the present invention, including the fluid pressurization of chamber54via opening or openings40during use allows aperture36to retain its axial integrity and seal around the instrument56. The instrument56may comprise a variety of tools as small as a guidewire and up to large delivery catheters. Typically, during a medical procedure, the guidewire remains traversed through the aperture36.

FIGS. 6A-6Dare plan, side, and cross-sectional illustrations of a bifurcated introducer sheath58with which various embodiments of the present invention may be used. In this embodiment, the sheath58may be bifurcated comprising at least two hubs60,62coupleable to a proximal end of the shaft12. As shown inFIG. 6D, a first passive hemostatic valve64is incorporated into to the first hub60and a second passive hemostatic valve66is incorporated into to the second hub62. Each annulus region of the valves64,66is removably received within an inner lumen of the respective hubs60,62. The valves64,66may comprise any of embodiments described herein. Additionally, a conventional duckbill valve68may be removably received within one end (or both ends) of the bifurcated sheath58to prevent any fluid leakage from or into the shaft12when no instrument is traversing the valve64.

Referring now toFIG. 7, an introducer sheath10in accordance with another embodiment of the present invention is illustrated. The introducer sheath10generally comprises a tubular shaft12having a proximal end13and a distal end15, a two-piece hub14A,14B that is adapted for coupling to the proximal end13of shaft12. The hub comprises hub main body or housing14A and cap14B which may be coupled to one another by any appropriate means, such as by threading as shown inFIG. 7or by being press fit or mechanically snapped into place. A front seal17is disposed between the housing14A and a connector ferrule19at the proximal end13of the shaft12. The sheath10may be formed from any of the medical grade materials already described above.

As further illustrated inFIG. 7, an exemplary passive hemostatic valve16as described in more detail below may removably be positioned at a proximal portion of the introducer sheath10within the hub14A,14B and between the connector ferrule19and a connector isolator21. As noted above, the valve16alternatively may be integrally formed within the sheath10and positioned at any desired portion of the sheath10. A valve cartridge or spacer18also may be removably positioned integral with valve16as described above.

Referring now toFIGS. 8A through 8F, the passive hemostatic sheath valve16ofFIG. 7is illustrated in further detail. The valve16for creating a hemostatic seal around a medical instrument comprises a valve body20having an upstream end22and a downstream end24, as shown inFIG. 8F. The valve body20defines a lumen26having an inner surface28and an outer surface30therethrough, as shown inFIGS. 8B and 8C. The lumen26comprises an hourglass configuration having a funnel-or conical-shaped upstream lumen32that converges inwardly and a funnel-shaped downstream lumen34that diverges outwardly. The upstream and downstream lumens32,34intersect at a sealing aperture or hole36configured nominally to remain open (i.e., prior to, during, and subsequent to device insertion). In this embodiment, the funnel-shaped upstream and downstream lumens32,34are non-symmetric in that the upstream lead-in angle α is more obtuse that the downstream lead-in angle β as measured with respect to a central axis as shown inFIG. 8C. However, it will be appreciated that the funnel-shaped upstream and downstream lumens32,34may be symmetric, have equal (or even non-existent) lead-in angles, or still further equal or different lengths.

As shown inFIGS. 8D and 8E, the upstream end22includes an upstream annulus region38defining at least one opening40and the downstream end24includes a downstream annulus region42. In this embodiment, the upstream end20includes four equally spaced pressure equalization slots40so as to promote equal stress distribution within the valve body. It will be appreciated that slots40may comprise any alternative shape (e.g., circular shape, S-shape, diamond shape, etc.), number (e.g., one, two, three, four, five, six, etc.), and/or configuration (e.g., irregularly or symmetrically spaced) to achieve the desired pressure equalization. The slots40typically will have slot widths in a range from about 0.030 inch or less to about 0.075 inch or greater, as for example 0.045 inch.

As shown in the view ofFIG. 8F, the sealing aperture36comprises a variable orifice capable of accommodating and providing a fluid-tight seal around a wide range of medical instrument diameters. As described above, the valve16may further comprise at least one reinforcing rib52, typically four ribs52, extending from the upstream annulus region38to the downstream annulus region42, as shown inFIGS. 8B and 8C. The valve16may be formed from any of the medical device grade materials described above.

In operation, the slot openings40function similar to the hole openings illustrated inFIGS. 2Athough3F by transmitting pressure from the upstream end22via the upstream annulus region38so as to allow a fluid (e.g., blood, air, etc.) to enter the chamber54as a greater pressure is generally on the upstream side22. Pressure from the fluid entering the chamber54is exerted against the outer lumen surface wall30which symmetrically seals the aperture36around the instrument. Hence, the slot opening40advantageously allows for pressure normalization on the upstream22and downstream24ends of the valve body20so that the valve body is less likely to inflate and leak fluids from or into the introducer sheath10when medical tools are inserted into or withdrawn from the sealing aperture36. It is also believed that the fluid pressurization of chamber54via slot openings40during use allows aperture36to retain its axial integrity and seal around the instrument56.

Although certain exemplary embodiments and methods have been described in some detail, for clarity of understanding and by way of example, it will be apparent from the foregoing disclosure to those skilled in the art that variations, modifications, changes, and adaptations of such embodiments and methods may be made without departing from the true spirit and scope of the invention. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.