Patent ID: 12186500

Repeated use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention according to the disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to certain embodiments of the present invention, examples of which are illustrated in the accompanying Figures. These embodiments are provided by way of example, and should not be construed as limiting the scope of the claimed invention to any particular embodiment. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope and spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the recited claims and their equivalents.

In the descriptions of steerable introducer sheath embodiments that are provided herein, the terms “distal” and “proximal” will be used to describe both movement and relative position. As can be seen inFIGS.1A-1D, the term “distal” signifies relative position and/or movement in the direction of terminal end136of introducer sheath130(i.e., in the direction of the patient), and “proximal” signifies relative position and/or movement in the direction of device lock assembly192(i.e., in the direction of the user).

In the descriptions within, the term “about” should be interpreted as +/−10%.

Steerable introducer sheath assemblies embodying the present disclosure comprise an introducer sheath portion that extends in a distal fashion from a handle portion that may be held and manipulated by a user. One or more steering cables are affixed to the distal end of the introducer sheath, passed proximally through longitudinal steering cable lumens within the introducer sheath to the interior of the handle portion, wherein the proximal ends of the steering cables are engaged by at least one mechanism that allows a user to manipulate the distal end of the introducer sheath by selectively increasing or decreasing the steering cable tension. The precise location at which the distal ends of the steering cables are affixed at or near the distal tip of the introducer sheath may be varied proximally or distally, as necessary, to provide for the desired amount of distal curvature modification when the steering cable tension is increased or decreased. The introducer sheath portion further contains a longitudinal device lumen that is capable of slidably receiving a catheterized instrument, which can include a dilator (as depicted inFIGS.8C and8D, for example) through which standard length Bayliss RF transseptal devices (available from Bayliss Medical, Montreal, Canada), Brockenbrough transseptal needles, or other similar instruments. The handle portion further contains features that allow the user to finely control the advancement of the catheterized instrument through the introducer sheath.

FIGS.1A and3Aillustrate exemplary features of a steerable introducer sheath assembly in accordance with an embodiment of the present disclosure. As best shown inFIG.1A, the steerable introducer sheath assembly may include a handle portion110, and an introducer sheath130extending outwardly from the distal end (116) of handle portion110. As best shown inFIG.3A(depicting a planar cross section of introducer sheath130that is perpendicular to longitudinal center axis102), introducer sheath130may contain a more or less centrally located device lumen140that is configured to slidably receive a catheterized instrument (e.g., dilator159shown inFIGS.8A and8C, and discussed herein), first and second steering cable lumens146and148in which are slidably disposed first and second steering cables154and156(respectively), and third steering cable lumen150, in which is slidably disposed third steering cable158.

Referring again to the introducer sheath depicted inFIG.3A, first and second steering cable lumens146and148may be disposed on opposite sides of device lumen140, along a horizontal plane formed by horizontal axis104and longitudinal center axis102, and symmetric about a vertical plane formed by vertical axis103and longitudinal center axis102, with the horizontal and vertical planes being perpendicular to each other. As such, adjusting the tension in first and second steering cables154and156adjusts the “horizontal” curvature of the introducer sheath's distal portion132to the left or right of the vertical plane, while minimizing the potential unintended motion within the vertical plane. As further depicted inFIG.3A, third steering cable lumen150and device lumen are disposed along the vertical plane, with third steering cable lumen150disposed above device lumen140(i.e. closer to a user viewing the steerable introducer sheath from the “top” view illustrated inFIG.1C). As such, adjusting tension on third steering cable158will adjust the “vertical” curvature of distal portion132of introducer sheath130within the vertical plane while minimizing any unwanted deflection of introducer sheath130to the left or right of the vertical plane. In other words, when an operator views sheath assembly100from the proximal handle portion110and looks distally along introducer sheath130as it extends outwardly in an undeflected position, first steering cable154and second steering cable156may be utilized to effect “horizontal” curvature of the distal portion132of introducer sheath130to the left and to the right, respectively, of axis102(as best shown inFIG.1C), and third steering cable158may be utilized to adjust the amount of “vertical” curvature of distal portion132of the introducer sheath130, thereby lifting distal portion132“upwards” (i.e. towards the user) from axis102(as best shown inFIG.1D).

Other embodiments of the steerable introducer sheath assembly of the present disclosure may include an introducer sheath as depicted inFIG.3B(depicting a planar cross section of introducer sheath1300that is perpendicular to longitudinal center axis102), which contains a more or less centrally located device lumen1400that is configured to slidably receive a catheterized instrument (e.g., dilator159shown inFIGS.8A and8C, and discussed herein), first and second steering cable lumens1460and1480in which are slidably disposed first and second steering cables1540and1560(respectively), and third and fourth steering cable lumens1500and1420, in which are slidably disposed third and fourth steering cables1580and1520(respectively). As further depicted inFIG.3B, first and second steering cable lumens1460and1480are disposed on opposite sides of device lumen1400, along a horizontal plane formed by horizontal axis104and longitudinal center axis102, and symmetric about a vertical plane formed by vertical axis103and longitudinal center axis102, with the horizontal and vertical planes being perpendicular to each other. Third and fourth steering cable lumens1500and1420are disposed on opposite sides of device lumen140, along the vertical plane formed by vertical axis103and longitudinal center axis102, and symmetric about the horizontal plane formed by horizontal axis104and longitudinal center axis102.

For introducer sheaths with the cable arrangement shown inFIG.3B, adjusting the tension in first and second steering cables1540and1560modifies the “horizontal” curvature of the distal portion of the introducer sheath in the direction of horizontal axis104(i.e., to the left or right of the vertical plane). This is best shown inFIG.6C, which depicts introducer sheath1300with “horizontal” curvature to the left of the vertical plane (FIG.6C, left), introducer sheath1300with no “horizontal” curvature (FIG.6C, center), and introducer sheath1300with “horizontal” curvature to the right of the vertical plane (FIG.6C, right). Similarly, adjusting the tension in third and fourth steering cables1580and1520modifies the “vertical” curvature of the distal portion of the introducer sheath in the direction of vertical axis103(i.e., curving either above or below the horizontal plane). This is best shown inFIG.6D, which depicts introducer sheath1300with “vertical” curvature below the horizontal plane (FIG.6D, left), introducer sheath1300with no “vertical” curvature (FIG.6D, center), and introducer sheath1300with “vertical” curvature above the horizontal plane (FIG.6D, right).

The handle portion of a steerable introducer sheath assembly in accordance with an embodiment of the present disclosure includes features that allow a user to selectively increase or decrease the steering cable tension in order to achieve a desired “horizontal” or “vertical” curvature to the distal portion of the introducer sheath. As best illustrated inFIGS.1B-1D, for example, handle portion110may include a steering lever160for adjusting the tension in the first and second steering cables so as to modify the “horizontal” curvature of distal portion132of introducer sheath130(as best depicted inFIG.1Cand further discussed below), and a distal end cap180for adjusting the tension in the third steering cable so as to modify the “vertical” curvature of distal portion132of introducer sheath130(as best depicted inFIG.1Dand further discussed below).

In certain embodiments the mechanism for manipulating first steering cable154and second steering cable156to adjust the amount of “horizontal” curvature of distal portion132of the introducer sheath may comprise an external steering lever160that controls an internal system of drive gears and rotational posts that are coupled to steering cables154and156. As best illustrated inFIGS.2A,5A, and5B, for example, a steering lever160may be pivotably secured to a first end of a steering post164by way of bores that align to receive steering lever pin198. Steering post164is non-rotatably secured to a drive gear166at its second end. Drive gear166is situated within handle100so that is capable of simultaneously engaging and rotating both a first gear assembly168, and a second gear assembly174. As best shown inFIG.2A, first and second gear assemblies168and174may each comprise a rotatable post (126,128) that extends inwardly from a housing on the interior of handle100, a non-rotatably-secured barrel portion (172,178), and a non-rotatably-secured gear (170,176) that engages drive gear166. Posts126and128may be situated perpendicular to center axis102(as depicted inFIGS.2A,5A, and5B, for example), or alternatively at a non-perpendicular angle to center axis102. Posts126and128may be rotationally engaged by retaining features extending inwardly from the interior faces of the upper housing portion112, the lower housing portion114, or both. For example, as best shown inFIG.5C(depicting seating flanges and showing the engagement of post126with a seating flange1914in lower housing portion114), in some embodiments posts126and128may be rotationally engaged by circular seating flanges1914in upper housing portion112and lower housing portion114.

As briefly noted above and best illustrated inFIGS.1A and2A, the distal ends of first steering cable154and second steering cable156are affixed at or near the distal tip136of introducer sheath, with the cables themselves extending proximally through steering lumens146and148(respectively) until the proximal ends terminate in the interior of handle portion110, wherein the proximal ends of both cables may be engaged by one or more steering mechanisms that are capable of selectively increasing or decreasing the tension in the steering cables.

For example, as best shown inFIG.2A, first and second steering cables154and156may exit introducer sheath130via respective openings1960and1961, which are located near the terminal portion of introducer sheath130(i.e., the portion that is located inside of handle portion110). In this way, the proximal ends of first and second steering cables154and156are able to pass out of steering lumens146and148(respectively), and become engaged with first and second steering gear assemblies168and174(respectively). For embodiments of the steerable introducer sheath assembly of the present disclosure that include an introducer sheath similar to introducer sheath1300that is shown inFIG.3B, the proximal ends of first and second steering cables1540and1560pass out of first and second steering cable lumens1460and1480(respectively) via similar openings to those shown inFIG.2A(1960and1961), and become engaged with first and second steering gear assemblies168and174(respectively).

As best shown inFIG.2A, for example, in some embodiments the proximal end of first steering cable154is affixed to barrel portion172of first gear assembly168, and the proximal end of second steering cable156is affixed to barrel portion178of second gear assembly174. Drive gear166is engaged with both first gear170and second gear176such that rotation of drive gear166causes first and second gear assemblies168and174to rotate simultaneously, thereby adjusting the tension applied to first and second steering cables154and156, which are affixed to and wrapped around barrel portions172and178, respectively, in a manner such that when the tension in one of the steering cables is increased due to rotation of steering lever160, the tension in the other steering cable is decreased. As such, first and second steering cables154and156work in unison to either increase or decrease the “horizontal” curvature of distal portion132to either the left or right of axis102.

In certain embodiments, first and second steering cables154and156are affixed to and engaged by barrel portions172and178, respectively in such a manner that, viewing handle portion110from the “top” as best illustrated inFIG.1C, turning steering lever160in a counterclockwise fashion (i.e. so that the distal end of steering lever160points more to the “left” with respect to longitudinal center axis102) causes the distal portion (136) of introducer sheath130to become “horizontally” curved more to the left of longitudinal center axis102(FIG.1C, at left), turning steering lever160in a clockwise fashion (i.e. so that the distal end of steering lever160points more to the “right” with respect to longitudinal center axis102) causes the distal portion (136) of introducer sheath130to become “horizontally” curved more to the right of longitudinal center axis102(FIG.1C, at right), and returning steering lever160to the center position (i.e. so that the distal end of steering lever160points in a parallel direction to longitudinal center axis102) causes distal portion (136) of introducer sheath130to extend in a parallel direction to longitudinal center axis102(i.e. with no “horizontal” curvature, as inFIG.1C, at center). In this fashion, the orientation of the distal end of steering lever160may provide the user with an indication as to the presence, directionality, and relative extent of any “horizontal” curvature that has been introduced to the distal portion (136) of introducer sheath130.

In alternative embodiments, first and second steering cables154and156may be affixed to and engaged by barrel portions172and178such that turning the steering lever in a “counterclockwise” fashion will cause the distal portion (136) of introducer sheath130to be “horizontally” curved to the right, and vice-versa.

In certain embodiments of the steerable introducer sheath assembly in accordance with the present disclosure, the interactions between steering lever160, drive gear166and/or first and second gear assemblies168and174may be may modified to either increase or decrease the “sensitivity” of steering lever160(i.e. the extent to which “horizontal” curvature is introduced when steering lever160is rotated to a particular degree). For example, in certain embodiments a variable transmission may be provided that allows the user to modulate the “sensitivity” of steering lever160by selectively modifying the gearing ratios between drive gear166and/or first and second gear assemblies168and174. Alternatively, spring-loaded gear posts and/or flywheel assemblies may be provided for modulating the sensitivity of steering lever160in a desired fashion.

In certain embodiments, the steerable introducer sheath assembly may include a mechanism for locking the steering lever in place once a desired amount of curvature has been achieved for the introducer sheath. As shown inFIGS.5A and5B, for example, steering lever160may include a camming surface162, such that when steering lever160is rotated upwardly about steering lever pin198from the “unlocked” position (FIG.5A) to the “locked” position (FIG.5B), camming surface162becomes frictionally engaged with the outer surface of upper handle portion112, and steering post164is lifted in a radial direction away from the interior of the handle such that drive gear166becomes frictionally engaged with the interior surface of upper handle portion112. In certain embodiments, this “locking” friction may be modulated by providing one or more washers to separate drive gear166and the interior surface of upper handle portion112, which may for example include wave spring washer1915depicted inFIGS.5A and5B.

As shown inFIGS.5A,5B, and5D, certain embodiments may include a dome cover1916that sits within a dome cover recess1917extruding from the exterior face of upper handle portion112, thereby mediating the interaction between camming surface162of steering lever160, and the outer surface of upper handle portion112. As best shown inFIG.5D(inset), dome cover1916may be shaped to provide a central slot1917through which steering lever160protrudes, with recess1917of sufficient width to accommodate vertical rotation between the “unlocked” and “locked” positions, while also providing lateral support for steering lever160when it is manipulated to turn steering post164, and further ensuring that when pivoted from the “unlocked” position (FIG.5A) to the “locked” position (FIG.5B), steering lever160is constrained to a direction that is perpendicular to the line of axis of steering lever pin198.

In certain embodiments, dome cover1916and dome cover recess1917may be configured to limit the angular displacement of steering post164about its longitudinal axis when steering lever160is manipulated. As shown inFIG.5D, for example, this may be achieved through flanges (1918and1919) that extend from the underside of dome cover1916, and interact with the distal faces formed by corresponding protrusions1920and1921(respectively) to constrain the rotation of steering lever160. This protects cables154and156from the excessive strain that could result from a user's attempt to overtighten them using steering lever160. In certain embodiments, protrusions1920and1921and/or flanges1918and1919may be adjustable, so that the extent to which the rotation of steering lever160is restricted can be modified according to the user's preferences.

For embodiments of the steerable introducer sheath assembly of the present disclosure that feature introducer sheaths with the cable arrangement shown inFIG.3B, a steering lever with the steering assembly mechanisms and other associated features described above may likewise be used to adjust the tension in first and second steering cables1540and1560to modify the “horizontal” curvature of the distal portion of the introducer sheath in the direction of horizontal axis104(i.e., to the left or right of the vertical plane). For such embodiments, first and second steering cables1540and1560are affixed to and engaged by barrel portions172and178in the same manner as described above (and illustrated inFIG.2A) for first and second steering cables154and156from introducer sheath130. As such, when viewed from the “top” as illustrated inFIGS.1C and6C, turning steering lever160in a counterclockwise fashion (i.e. so that the distal end of steering lever160points more to the “left” with respect to longitudinal center axis102) causes the distal portion (1360) of introducer sheath1300to become “horizontally” curved more to the left of longitudinal center axis102(FIG.6Cat left), turning steering lever160in a clockwise fashion (i.e. so that the distal end of steering lever160points more to the “right” with respect to longitudinal center axis102) causes the distal portion (1360) of introducer sheath1300to become “horizontally” curved more to the right of longitudinal center axis102(FIG.6C, at right), and returning steering lever160to the center position (i.e. so that the distal end of steering lever160points in a parallel direction to longitudinal center axis102) causes distal portion (1360) of introducer sheath1300to extend in a parallel direction to longitudinal center axis102(i.e. with no “horizontal” curvature, as inFIG.6C, at center). Here again, the orientation of the distal end of steering lever160signifies the presence, directionality, and relative extent of any “horizontal” curvature that has been introduced to the distal portion (1360) of introducer sheath1300.

This is best shown inFIG.6C, which depicts introducer sheath1300with “horizontal” curvature to the left of the vertical plane (FIG.6C, left), introducer sheath1300with no “horizontal” curvature (FIG.6C, center), and introducer sheath1300with “horizontal” curvature to the right of the vertical plane (FIG.6C, right). Similarly, adjusting the tension in third and fourth steering cables1580and1520modifies the “vertical” curvature of the distal portion of the introducer sheath in the direction of vertical axis103(i.e., curving either above or below the horizontal plane). This is best shown inFIG.6D, which depicts introducer sheath1300with “vertical” curvature below the horizontal plane (FIG.6D, left), introducer sheath1300with no “vertical” curvature (FIG.6D, center), and introducer sheath1300with “vertical” curvature above the horizontal plane (FIG.6D, right).

As previously mentioned, the handle portion of a steerable introducer sheath in accordance with an embodiment of the present disclosure may also include features that allow a user to selectively increase or decrease the steering cable tension in order to achieve a desired “vertical” curvature to the distal portion of the introducer sheath. For example, handle portion110may include a distal end cap180that controls the axial motion of externally-threaded stem188, thereby adjusting the tension in the third steering cable so as to modify the “vertical” curvature of distal portion132as shown inFIG.1D(at left and center).

As can be seen inFIGS.1A-1D, handle portion110may include an upper housing portion112and a lower housing portion114that together define a distal aperture118disposed at the distal end (116) of handle portion110. In certain embodiments, distal aperture118may be configured to rotatably receive distal end cap180so that distal end cap180is free to rotate relative to handle portion110. For example, as illustrated inFIGS.2A &2B and7B, distal end cap180may include a plurality of ridges182extending radially outwardly from the outer surface so that distal end cap180may be readily grasped and rotated during use. Distal end cap180may further include an internally threaded portion186that engages correspondingly threaded stem188that is disposed within handle portion110. Distal end cap180may further include an outwardly depending radial flange that is disposed at its proximal end, the diameter of which is greater than the diameter of distal aperture118, thereby allowing distal end cap180to be received and axially retained within annular cavity120that is defined by the joining of upper housing portion112and a lower housing portion114to form handle portion110.

As best shown inFIGS.2A-Band7B, in certain embodiments the outwardly depending radial flange disposed at a proximal end of distal end cap180may be comprised of a plurality of tabs184with outwardly depending members that together define a discontinuous radial flange with a radius that is greater than that of distal aperture118so that distal end cap180may be received and axially retained within annular cavity120. As best shown inFIG.2B, distal end cap180may further include a plurality of vents1850corresponding to tabs184in an arrangement that facilitates the use of injection molding techniques to manufacture a distal end cap180.

As can be seen inFIGS.4A and4B, externally-threaded stem188may include one or more axially extending slots189that can engage one or more axially extending flanges129that depend radially inwardly from an inner surface of handle110. When distal end cap180is rotated, the engagement of slot(s)189and flange(s)129ensures that externally-threaded stem188does not also rotate, as a result of which externally-threaded stem188moves axially (i.e. parallel to longitudinal center axis102) in either a proximal or distal direction when the user rotates distal end cap180. As discussed in greater detail below, the axial motion of externally-threaded stem188that results from the rotation of distal end cap180is utilized to introduce “vertical” curvature to distal portion132of introducer sheath130.

To ensure that force is properly transferred to the distal portion132of introducer sheath130during operation (for example, when the user increases or decreases the tension in one or more of the steering cables to introduce “horizontal” and/or “vertical” curvature to the proximal end of introducer sheath130), the steerable introducer sheath in accordance with an embodiment of the present disclosure may further include a torque transmission lock that prevents introducer sheath130from rotating about longitudinal center axis102. For example, as best shown inFIGS.4A and4B, certain embodiments may include a torque transmission lock1900comprising a hollow column with an external diameter that allows it to pass through the inner bore of externally-threaded stem188, an internal diameter sufficient to encompass the radial diameter of introducer sheath130, and a recess1901at its proximal end that is capable of engaging with flange129. The distal end of torque transmission lock1900includes external threading1902that corresponds to the threading on the internal bore of transmission lock cap1903. When threaded onto transmission lock1900, the proximal face of transmission lock cap1903is capable of movably engaging with the distal face of distal end cap180to secure transmission lock1900within the bore of externally-threaded stem188, with recess1901fully engaged to flange129. In certain embodiments, the movable engagement between transmission lock cap1903and distal end cap180may be facilitated through the use of a thrust bearing1905that may be seated within an indentation1904on the distal face of distal end cap180. In the final assembly, introducer sheath130is passed through the bore of torque transmission lock1900and immovably affixed thereto, and thus the engagement of recess1901with flange129prevents introducer sheath130from rotating about longitudinal center axis102when “vertical” curvature is introduced using distal end cap180, or when “horizontal” curvature is introduced using steering lever160.

The proximal terminus of third steering cable158may be affixed to externally-threaded stem188such that the tension of third steering cable158may be increased or decreased by rotating distal end cap180, which causes externally-threaded stem188to move distally or proximally along axis102. As best shown inFIGS.1A and2D, for example, the distal terminus of third steering cable158is affixed at or near the distal tip136of introducer sheath130, and from there extends proximally through steering lumen150until the proximal end terminates in the interior of handle portion110, whereupon third steering cable158exits introducer sheath130via opening1963that is located near the terminal portion of introducer sheath130(i.e., the portion that is located inside of handle portion110). In this way, the distal end of third steering cable158is able to pass out of steering lumen150and become affixed to externally-threaded stem188, which is accomplished by passing third steering cable158through axial bore1963in flange400that extends from the proximal end of externally-threaded stem188, and affixing third steering cable158after it has exited from the distal end of axial bore1963. Likewise, for embodiments of the steerable introducer sheath assembly of the present disclosure that include an introducer sheath similar to introducer sheath1300that is shown inFIG.3B, the distal end of third steering cable1580passes out of steering cable lumen1500and exits introducer sheath1300via an opening that is essentially identical to opening1963that is shown inFIG.2Dand discussed above. Once it has passed out of introducer sheath1300, third steering cable1580may be affixed to externally-threaded stem188by passing it through axial bore1963in flange400that extends from the proximal end of externally-threaded stem188, and affixing third steering cable1580after it has exited from the distal end of axial bore1963.

As best illustrated inFIGS.2A, and2D, when an operator views sheath assembly100from the proximal handle portion110and looking distally along introducer sheath130as it extends outwardly in an undeflected position, rotation of distal end cap180in a clockwise direction causes the correspondingly-threaded stem188to move in a proximal direction (i.e. towards the interior of handle portion110, as best shown inFIG.2D, top), which increases the amount of tension placed on third steering cable158, and thereby causes an increase in the “vertical” curvature of the distal portion132of introducer sheath130. Conversely, rotation of distal end cap180in a counterclockwise direction causes externally-threaded stem188to move in a distal fashion (i.e. away from the interior of handle portion110, as best shown inFIG.2D, bottom), which reduces the amount of tension present in third steering cable158, and reduces the amount of “vertical” curvature present in distal portion132of introducer sheath130. This “vertical” curvature of distal portion136of introducer sheath130can be seen inFIG.1D(depicting a steerable introducer sheath as viewed from the “right hand” side), which illustrates how distal portion (136) of introducer sheath130extends in a parallel direction to longitudinal center axis102when distal cap180has been rotated such that externally-threaded stem188places no tension on steering cable158(FIG.1D, at center), and how distal portion (136) of introducer sheath130becomes more “vertically” curved in a direction that is elevated with respect to longitudinal center axis102(FIG.1D, at left) when distal end cap180has been rotated so as to cause externally-threaded stem188to move in a proximal fashion and increase the tension on steering cable158. A “self-locking” functionality that preserves the desired “vertical” curvature may be provided by configuring the threaded portions of distal end cap180and externally-threaded stem188to interact with sufficient friction that when a user ceases rotation of distal end cap180, externally-threaded stem188remains fixed in its position, thereby maintaining the tension in third steering cable158, and preserving the desired “vertical” curvature to distal portion132of introducer sheath130.

In certain embodiments of the introducer sheath assembly of the present disclosure, the engagement between end cap180and externally-threaded stem188may be used to modulate the “vertical” curvature of an introducer sheath that is similar to introducer sheath1300that is depicted inFIG.3B. In these embodiments, the proximal/distal movement of externally-threaded stem188is utilized (directly or indirectly) to selectively increase or decrease the relative tension in third and fourth steering cables1580and1520, thereby modifying the “vertical” curvature of distal portion1360of introducer sheath1300in the direction of vertical axis103(i.e., above or below the horizontal plane). This “vertical” curvature of distal portion136of introducer sheath130can be seen inFIG.1D(depicting a steerable introducer sheath as viewed from the “right hand” side), which illustrates how distal portion (1360) of introducer sheath1300extends in a parallel direction to longitudinal center axis102when distal cap180has been rotated such that externally-threaded stem188places no tension on third and fourth steering cables1580and1520(FIG.1D, at center), how distal portion (1360) of introducer sheath1300becomes more “vertically” curved in a direction that is elevated with respect to longitudinal center axis102(FIG.1D, at left) when distal end cap180has been rotated so as to cause externally-threaded stem188to move in a fashion that increases the tension on third steering cable1580and decreases the tension on fourth steering cable1520(FIG.1D, at left), and how distal portion (1360) of introducer sheath1300becomes more “vertically” curved in a direction that is depressed with respect to longitudinal center axis102(FIG.1D, at right) when distal end cap180has been rotated so as to cause externally-threaded stem188to move in a fashion that increases the decreases the tension on third steering cable1580and increases the tension on fourth steering cable1520.

Certain embodiments of the steerable introducer sheath assembly may include both a “horizontal” steering lever for modulating the amount of “horizontal” curvature present in the distal portion of the introducer sheath (as described above and depicted inFIGS.1A-1D and2A, and a “vertical” steering lever for modulating the amount of “vertical” curvature present in distal portion132of introducer sheath130. In such “dual lever” embodiments, the use of a “vertical” steering lever instead of the distal end cap and externally-threaded stem assembly described above for controlling “vertical” curvature provides uniformity with respect to the mechanisms for altering the curvature of the introducer sheath (i.e., the same type of mechanism—a steering lever—is used to modify both “vertical” and “horizontal” curvature).

For example, as shown inFIGS.6A-6D, the distal end cap180and its associated components (externally-threaded stem188, torque transmission lock1900, transmission lock cap1903, and thrust bearing washer1905) from the steerable introducer sheath assembly depicted inFIGS.1A-1C and4A-4Bmay be replaced with a distal housing assembly350, which as best shown inFIG.6Bincludes distal housing portions361and362that together house a vertical steering assembly351that is articulated by vertical steering lever360. As best shown inFIG.6B, vertical steering lever360is non-rotatably secured to a first end of steering post364by way of bores that align to receive a retaining pin. Steering post364, in turn, passes through distal housing portion361and is non-rotatably secured to main vertical drive gear365at its second end. Main vertical drive gear365is situated within distal housing assembly350so that is capable of simultaneously engaging and rotating both upper vertical drive gear366and lower vertical drive gear369. Upper vertical drive gear366is non-rotatably secured to upper rotatable post367, which extends inwardly from housings374and375on the interior of distal housing portions361and362(respectively), with upper rotatable post367further being non-rotatably secured to upper barrel portion368. Lower vertical drive gear369is non-rotatably secured to lower rotatable post370, which extends inwardly from housings376and377on the interior of distal housing portions361and362(respectively), with lower rotatable post370further being non-rotatably secured to lower barrel portion371.

In certain embodiments of the steerable introducer sheath assembly of the present disclosure, a vertical steering lever and associated elements described above may be provided in combination with an introducer sheath that is similar to introducer sheath1300that is depicted inFIG.3B. In these embodiments, third and fourth steering cables1580and1520are affixed at or near the distal tip1360of introducer sheath1300, with the cables themselves extending proximally through lumens1500and1420(respectively) until the proximal ends terminate in the interior of handle portion110, whereupon the proximal ends of third and fourth steering cables1580and1520pass out of steering cable lumens1500and1420(respectively) and exit introducer sheath1300via similar openings to those openings (1960and1961) depicted inFIG.2A, and become engaged with one or more steering mechanisms that are capable of selectively increasing or decreasing the tension in third and fourth steering cables1580and1520.

In these embodiments, the proximal end of third steering cable1580is affixed to upper barrel portion368, and the proximal end of fourth steering cable1520is affixed to lower barrel portion371. Rotation of vertical steering lever360causes main vertical drive gear365to simultaneously engage with and rotate upper and lower vertical drive gears366and369, and their associated upper and lower barrel portions368and371. This in turn causes third steering cable1580and fourth steering cable1520to become coiled about lower barrel portions368and371, respectively, so that as the tension in third steering cable1580becomes increased, the tension in fourth steering cable1520becomes decreased, and vice versa. As such, third and fourth steering cables1580and1520work in unison to either increase or decrease the “vertical” curvature of distal portion1320of introducer sheath1300in a direction that is either elevated above or depressed below the horizontal plane.

For example, in certain embodiments, first and second steering cables1580and1520may be affixed to and engaged by their respective upper and lower barrel portions368and371in such a manner that, as best illustrated inFIG.6D(providing views of a “two lever” steerable introducer sheath viewed from the “right hand” side), the rotation of steering lever360in a counterclockwise fashion (i.e., so that the distal end of steering lever360is pointing in a direction that is elevated relative to longitudinal center axis102) causes the distal portion (1360) of introducer sheath1300to “vertically” curve in an elevated fashion with respect to longitudinal center axis102(FIG.6D, at left), turning steering lever360in a clockwise fashion (i.e. so that the distal end of steering lever360is pointing in a direction that is depressed relative to longitudinal center axis102) causes the distal portion (1360) of introducer sheath1300to “vertically” curve in a depressed fashion with respect to longitudinal center axis102(FIG.6D, at bottom), and returning steering lever160to the center position (i.e. so that the distal end of steering lever360points in a parallel direction to longitudinal center axis102) causes distal portion (1360) of introducer sheath1300to extend in a parallel direction to longitudinal center axis102(i.e. with no “horizontal” curvature, as inFIG.6D, at center). In this fashion, the orientation of the distal end of steering lever360may provide the user with an indication as to the presence, directionality, and relative extent of any “horizontal” curvature that has been introduced to the distal portion (1360) of introducer sheath1300.

In alternative embodiments, third and fourth steering cables1580and1520may be affixed to and engaged by barrel portions368and371, respectively, such that turning vertical steering lever360in a “clockwise” fashion will cause the distal portion (1360) of introducer sheath1300to “vertically” curve above longitudinal center axis102, and vice versa.

In certain embodiments of the introducer sheath assembly of the present disclosure, a vertical steering lever and certain associated elements similar to those described above may be provided in combination with an introducer sheath that is similar to introducer sheath130that is depicted inFIG.3A. For example, the vertical steering lever may be secured to a first end of a rotatable post that extends through the surface of distal handle assembly350and terminates internally in a similar fashion to that which is shown inFIG.6Bwith respect to vertical steering lever360and rotatable post364. The distal end of third steering cable158from introducer sheath130is (directly or indirectly) affixed to and engaged by rotatable post364so that when steering lever360is rotated as described above, the resulting axial rotation of rotatable post364causes the proximal end of third steering cable158to become either coiled or uncoiled from around the barrel portion of rotatable post364. As third steering cable158becomes more coiled around the barrel portion of rotatable post364, the tension placed on third steering cable158is increased, and the amount of “vertical” curvature present in distal portion132of the introducer sheath is likewise increased. Conversely, as third steering cable158becomes less coiled around the barrel portion of rotatable post364, the tension placed on third steering cable158is decreased, and the amount of curvature present in distal portion132of introducer sheath130is likewise reduced. For example, in certain embodiments third steering cable158may be affixed to and engaged by rotatable post364in such a manner that, as best illustrated inFIG.6D(providing views of a “two lever” steerable introducer sheath viewed from the “right hand” side), the rotation of steering lever360in a counterclockwise fashion (i.e., so that the distal end of steering lever360is elevated relative to longitudinal center axis102) causes the distal portion (1360) of introducer sheath1300to “vertically” curve above longitudinal center axis102(FIG.6D, at left), and returning steering lever160to the center position (i.e. so that the distal end of steering lever360points in a parallel direction to longitudinal center axis102) causes distal portion (1360) of introducer sheath1300to revert to extending in a direction that is parallel to longitudinal center axis102(i.e. with no “vertical” curvature, as inFIG.6D, at center). Here again, the orientation of the distal end of steering lever360provides an indication as to the presence, directionality, and relative extent of any “vertical” curvature that has been introduced to the distal portion (1360) of introducer sheath1300.

In certain embodiments of the steerable introducer sheath assembly in accordance with the present disclosure, the interactions between the vertical steering lever and associated steering gear assemblies such as those described above for vertical steering lever360may modified to either increase or decrease the “vertical sensitivity” of the vertical steering lever (i.e. the extent to which “vertical” curvature is modified when the vertical steering lever is rotated to a particular degree). For example, in certain embodiments a variable transmission may be provided that allows the user to modulate the “vertical sensitivity” by selectively modifying the gearing ratios between the drive gear and any associated gear assemblies (for example, allowing the user to modify the respective gear ratios contained within vertical steering assembly351that is shown inFIG.6B). Alternatively, spring-loaded gear posts and/or flywheel assemblies may be provided for modulating the sensitivity of the vertical steering lever and associated steering assemblies.

Embodiments of the steerable introducer sheath assembly that provide a vertical steering lever for controlling “vertical curvature” (as detailed above) may further include a mechanism for locking the vertical steering lever in place once a desired amount of curvature has been achieved for the introducer sheath. As shown inFIG.6B, for example, distal handle assembly350may be configured with a vertical steering lever360that includes a camming surface385, such that when steering lever360is rotated upwardly about the steering lever pin that joins it to steering post364, the camming surface becomes frictionally engaged with exterior face of the upper portion (361) of distal handle assembly350, and steering post364(or an associated element) likewise becomes frictionally engaged with the interior face of the upper portion (361) of distal handle assembly350. This “locking engagement” is essentially the same as that which is depicted inFIGS.5A and5B, which depict horizontal steering handle160in an “unlocked” position (FIG.5A) and a “locked” position (FIG.5B). In certain embodiments, this “locking” friction may be modulated by providing one or more washers (for example, the wave spring washers (1915) depicted inFIGS.5A and5B) to mediate the frictional engagement with the interior and exterior faces of the upper portion (361) of distal handle assembly350.

Referring again toFIG.6B, embodiments of the steerable introducer sheath assembly that provide a vertical steering lever for controlling “vertical” curvature may further include a vertical steering lever dome cover380that sits within a vertical dome cover recess381extruding from the exterior face of the upper portion (361) of distal handle assembly350, and thereby mediating the interaction between camming surface385of vertical steering lever360, and the outer face of upper handle portion361. As best shown inFIG.6B(left inset), vertical steering lever dome cover380may be shaped to provide a central slot386through which steering lever360protrudes as shown inFIGS.6A and6D, with central slot386of sufficient width to accommodate vertical rotation of vertical steering lever360between the “unlocked” and “locked” positions, while also providing lateral support for steering lever360when it is manipulated to turn steering post364, and further ensuring that when pivoted from the “unlocked” position to the “locked” position (FIG.5B), steering lever360is constrained to a direction that is perpendicular to the line of axis of the steering lever pin that joins it to steering post364.

Referring again toFIG.6B, embodiments of the steerable introducer sheath assembly that provide a vertical steering lever for controlling “vertical” curvature, vertical dome cover380and vertical dome cover recess381may be configured to limit the angular displacement of steering post364about its longitudinal axis when vertical steering lever360is manipulated. For example, as best shown inFIG.6B, this may be achieved through flanges (381and382) that extend from the underside of vertical dome cover380, and interact with the distal faces formed by corresponding protrusions exemplified inFIG.6B(left inset) as383and384to constrain the rotation of steering lever360. This protects third steering cable1580and/or fourth steering cable1520from the excessive strain that could result from a user's attempt to overtighten them using steering lever360. In certain embodiments, protrusions383and384and/or flanges381and382may be adjustable, so that the extent to which the rotation of steering lever360is constrained can be modified according to the user's preferences.

As discussed above, first and second steering cables154and156work in unison to effect the curvature of distal portion132of introducer sheath130, with first and second gear assemblies168and174being simultaneously engaged by drive gear166so that when the operator manipulates steering lever160to increase the tension in steering cable154, the tension in steering cable156is lessened by the same amount, and vice versa. The simultaneous operation of gear assemblies168and174prevents slack from building up in either of first and second steering cables154and156when the user manipulates steering lever160to effect “horizontal” curvature of distal portion132of introducer sheath130. This is also true with respect to introducer sheath1300that is depicted inFIG.3B, where the introduction of “horizontal” curvature to distal portion1320of introducer sheath1300through manipulation of steering lever160likewise does not lead to slack buildup in first and second steering cables1540and1560, because as tension in one of the steering cables increases, the tension in the other steering cable decreases, and vice versa.

However, when a user increases the “vertical” curvature of distal portion132of introducer sheath130by increasing the tension of third steering cable158, this may in turn cause slack to build up in first steering cable154and/or second steering cable156. Likewise, when a user modifies the “vertical” curvature of distal portion1320of introducer sheath1300(in a direction that is either elevated or depressed with respect to the horizontal plane) by modulating the tension of third and fourth steering cables1580and1520, this may in turn cause slack to build up in first steering cable1540and/or second steering cable1560. This accumulation of slack may cause an operator to experience an undesirably delayed response when attempting to utilize a horizontal steering lever (e.g., steering lever160described above) to vary the tension in first and/or second steering cables154and156(or first and/or second steering cables1520and1580) so as to modulate the “horizontal” curvature of distal portion132of introducer sheath130(or distal portion1320of introducer sheath1300). To prevent this, steerable introducer sheath assemblies of the present disclosure may include a mechanism for removing such slack.

For example, as shown inFIGS.7A and7B, externally-threaded stem188may feature a proximally-extending linkage flange400by which the axial movement of externally-threaded stem188is transferred to a first slack removal assembly comprising first connecting arm401, second connecting arm402, flange linking post403with associated bearing cylinder406, connecting arm linking post404with associated bearing cylinder407, and connecting arm retaining post405with associated bearing cylinder408. More specifically as best shown inFIG.7B, linkage flange400is joined to the distal end of first connecting arm401by way of overlapping openings that receive flange linking post403; the proximal end of first connecting arm401is joined to the distal end of second connecting arm402by way of overlapping openings that receive connecting arm linking post404; and the proximal end of second connecting arm402contains an opening through which one end of connecting arm retaining post405is passed and then seated in connecting arm retaining post receptacle410on the interior of lower housing portion114. First steering cable154is threaded through this slack removal assembly as shown by the dotted line inFIG.7B, with bearing cylinders406-408configured to act as rollers that rotate freely about respective posts403-405, to minimizing friction with steering cable154. As further shown inFIG.7B, second linking cable156is threaded through a second slack removal assembly that is likewise coupled to linking flange400, with the second slack removal assembly comprising first connecting arm411, second connecting arm412, flange linking post413with associated bearing cylinder416, connecting arm linking post414with associated bearing cylinder417, and connecting arm retaining post415with associated bearing cylinder418, and these components joined together as described above with respect to the first slack removal assembly.

As best shown inFIG.7B, as externally-threaded stem188is advanced in a distal direction, the interaction between linking flange400and the slack removal assembly causes posts403-405and413-415(and associated bearings406-408and416-418) to become aligned in a more linear fashion, which in turn allows steering cables154and156to travel along a shorter path from their distal affixation points within introducer sheath130to their proximal affixation points at gear assemblies168and174. Conversely, as externally-threaded stem188is advanced in a more proximal direction, the interaction between linking flange400and the slack removal assembly causes posts403-405and413-415(and associated bearings406-408and416-418) to become aligned in a more triangular configuration, with connecting arm linking posts404and414situated considerably more towards the exterior of handle110than flange linking posts403and413, and connecting arm retaining posts405and415. This triangular configuration removes excess slack from steering cables154and156by causing them to travel along a longer path from their distal affixation points within introducer sheath130to their proximal affixation points at gear assemblies168and174. Thus, when externally-threaded stem188is advanced in a proximal direction that increases the tension on third steering cable158(which in turn increases “vertical” curvature that could cause steering cables154and156to become slackened), the slack removal assembly described above shifts into a triangular configuration that removes excess slack by increasing the distance traveled by cables154and156from their proximal gear assemblies to the distal tip of introducer sheath130.

Likewise, for those embodiments in which a “vertical” steering lever360is used (i) in connection with introducer sheath1300that is depicted inFIG.3B, where the vertical steering lever360is rotated to modulate the “vertical” curvature of distal portion1320of introducer sheath1300(as discussed above and best illustrated inFIGS.6B and6D), or (ii) in connection with introducer sheath130that is depicted inFIG.3A, whereby the vertical steering lever360is rotated to modulate the “vertical” curvature of distal portion132of introducer sheath130(as discussed above and best illustrated inFIGS.6B and6C) the potential introduction of slack into first and/or second steering cables1520and1580(from introducer sheath1300), or first and/or second steering cables154and156(from introducer sheath130) may be addressed by coupling the rotation of steering post364to the slack removal assembly. For example, one or more coupling rods or cables may be provided to couple steering post364to the slack removal assembly such that when a user increases the tension in third steering cable158by rotating steering post364using “vertical” steering lever360(thereby increasing the “vertical” curvature of distal portion132of introducer sheath130), the coupling rods or cables cause the slack removal assembly to become aligned in the “triangular” configuration that, as discussed above and shown inFIG.7B, acts to remove excess slack from steering cables154and156by causing them to travel along a longer path from their affixation points at the distal tip of introducer sheath130to their proximal affixation points at gear assemblies168and174. Conversely, when a user increases the tension in third steering cable158by rotating steering post364using “vertical” steering lever360(thereby reducing or eliminating any “vertical” curvature of distal portion132of introducer sheath130), the coupling rods or cables cause the slack removal assembly to become aligned in the more linear fashion that, as discussed above and shown inFIG.7B, allows steering cables154and156to travel along a shorter path from their distal affixation points within introducer sheath130to their proximal affixation points at gear assemblies168and174.

Steerable introducer sheath assemblies in accordance with the present disclosure may also include a device locking assembly that allows user to selectively fix a catheterized instrument within the introducer sheath after it has been advanced (or retracted) to the desired extent, and to further exert fine control over the advancement or retraction of a catheterized instrument that has been so affixed. Such catheterized instruments may include, for example, dilator through which standard length Bayliss RF transseptal devices (available from Bayliss Medical, Montreal, Canada), Brockenbrough transseptal needles, or other similar instruments may be introduced. As can be seen inFIGS.1A, and8A-8D, for example, such a device locking assembly may be disposed within the proximal aperture124(best shown inFIGS.8B and8C) that is formed when the proximal faces of upper housing portion112and a lower housing portion114are joined together to form handle portion110. As further shown inFIGS.8A-8D, the device locking assembly may include a device locking stem (shown as191ainFIGS.8A-8Cand as191binFIG.8D) that passes through the proximal face of handle portion110, with said device locking stem containing a smooth central bore (199) through which an instrument for catheterization may be passed and inserted into the steerable introducer sheath (130,1300), and said device locking stem being further configured to variably affix said instrument for catheterization in an immovable fashion. For example, as can best be seen from the depictions of device locking stem191athat are shown inFIGS.8B and8C, in certain embodiments the device locking stem may be externally threaded at its proximal end to receive a hemostatic valve cap (196a) through which an instrument for catheterization is passed as it is inserted into central bore199of the device locking stem, thereby allowing a user to selectively affix said instrument for catheterization in an immovable fashion within device locking stem191aby tightening or un-tightening hemostatic valve cap196a. Alternatively, as can best be seen from the depictions of device locking stem191bthat is shown inFIG.8D, in certain embodiments the device locking stem may define a distal collet194with smooth outer surfaces, allowing a user to selectively affix said instrument for catheterization in an immovable fashion within device locking stem191bby means of sliding lock knob196b, which defines a smooth frustoconical bore181that engages with and compresses collet194inwardly so that it tightens about said instrument for catheterization (which inFIG.8Dis represented by dilator159).

In certain embodiments, further control over the advancement (or retraction) of an instrument for catheterization (for example dilator159shown inFIGS.8A and8D) may be provided by configuring device locking stem (191a,191b) to be mechanically advanced (or retracted) through the proximal face of handle portion110after the instrument for catheterization has been affixed in an immovable fashion as described above. For example, as best illustrated inFIGS.8A-8C(showing device locking stem191a) andFIG.8D(showing device locking stem191b), the device locking stem may be configured with external threads1923that engage with a correspondingly threaded bore (197) that passes through an advance knob (195). The external threads on device locking stem (191a,191b) (including both the external threads that engage with threaded bore197, and the external threads at the proximal end of device locking stem191athat engage hemostatic valve cap196a) may be either continuous (i.e., “carried through”) or, as best shown inFIG.8E(depicting device locking stem191a), include interrupting “flats”1925situated along the length of the externally threaded areas to facilitate the use of injection molding manufacturing techniques.

Referring again toFIGS.8A-8D, the advance knob may be rotatably received and retained within proximal aperture124of handle portion110by a retention flange that extends radially from the distal portion of advance knob195with a greater diameter than proximal aperture124. This radially-extending retention flange may be either continuous or discontinuous. For example,FIG.8Dshows an advance knob195with a continuous retention flange (193b). Alternatively,FIG.2Cshows proximal, side perspective, and distal views of an advance knob195with a discontinuous retention flange comprising outwardly depending tabs1926that together define a flange with a radius that is greater than that of proximal aperture124, thereby ensuring that advance knob195is axially retained within handle portion110(as can best be seen inFIGS.2D and9A). As can best be seen inFIG.2C, where the advance knob (195) has a discontinuous retention flange, it may also include a plurality of vents1927that pass through the proximal face of advance knob195, which correspond to outwardly depending tabs1926, and are sized and situated to facilitate the use of injection molding techniques to manufacture the advance knob.

As best shown inFIG.9A, rotation of advance knob195causes device locking stem (191a,191b) to move in either a proximal direction (i.e. towards the user, as shown inFIG.9A, at left), or a distal direction (i.e. away from the user and into handle portion110, as shown inFIG.9A, at right). In certain embodiments, device locking stem (191a,191b) and advance knob195may be threaded such that rotation of advance knob195in a counterclockwise fashion causes device locking stem (191a,191b) to move in a proximal direction, and rotation of advance knob195in a clockwise fashion causes device locking stem (191a,191b) to move in a distal direction; in other embodiments the threading may be configured so that rotation of the advance knob in a clockwise fashion causes the device locking stem to move in a proximal direction, and rotation of the advance knob in a counterclockwise fashion causes the device locking stem to move in a proximal direction. Thus, after engaging device lock assembly192(which for the device locking stem191ashown inFIG.9Awould require tightening hemostatic valve cap196a) to affix the instrument for catheterization (for example the dilator (159) shown inFIGS.8A and8D), the user may exercise precise control over advancement of the instrument for catheterization's distal tip by rotating advance knob195, thereby causing the device locking stem (and axially-affixed instrument for catheterization) to move in either a distal fashion (extending the instrument towards and/or through the distal tip of the introducer sheath), or a proximal fashion (withdrawing the dilator back through and/or away from the distal tip of introducer sheath). This in turn facilitates the performance of delicate operations (such as puncturing the interatrial septum) in a very controlled manner.

The steerable introducer sheath assembly may also include an internal guide to prevent the device locking stem from instead being improperly rotated about axis102along with advance knob195when it is rotated, which in turn ensures that the device locking stem moves in a proper distal or proximal fashion along axis102when the user manipulates advance knob195. As best shown inFIGS.9A and9C, for example, internal guide1950may comprise a flat, cruciform distal base with a central bore that is defined by a hollow columnar stem extending in a proximal direction. As best shown inFIG.9B, the cruciform base of internal guide1950causes it to be seated in a rotationally-fixed manner within a guide channel that is defined by a set of parallel flanges1927that extend inwardly from the inner face of upper handle portion112, and a corresponding set of parallel flanges1928that extend inwardly from the inner face of lower handle portion114. The proximal end of internal guide1950is further configured to engage the device locking stem in a rotationally-fixed manner. For example, as best shown inFIG.9C, the engagement between internal guide1950and the device locking stem may be mediated by one or more indentations (1930) shown at the distal end of locking stem191a, which engage in a rotationally-fixed manner with one or more flanking bosses1929that extend proximally from the base of internal guide1950. In this manner, both the internal guide and externally-threaded stem are prevented from rotational movement when advance knob195is turned, and thus restricting device locking stem to an appropriate distal or proximal motion along axis102.

In certain embodiments, the handle portion110may include features that provide visual confirmation regarding the integrity of the seal between hemostatic introducer valve190and the dilator159(or other catheterized instrument) that has been inserted through hemostatic introducer valve190and into device lumen140of introducer sheath130. As best shown inFIG.8A, this may be achieved by way of an opening1931in upper housing portion112, which is situated to the proximal side of steering handle160and provides a “window” through which the distal face of hemostatic introducer valve190may be viewed. By regularly checking window1121, the user can readily identify signs (including the leakage of air, blood, or other fluids) that the hemostatic seal between hemostatic introducer valve190and a dilator159(or other catheter device) has become compromised, and take immediate action to correct the situation. Window1931may also allow users to visualize both the rate at which the dilator is being advanced, and the extent to which it has been advanced, and for this purpose the external surface of the dilator (or other instrument for catheterization) may be marked with gradations that can be viewed through window1931to provide the user with an indication of the extent to which the dilator (or other instrument for catheterization) has been advanced into (or retracted back through) the introducer sheath.

Certain embodiments of the present invention may include features for improving ultrasonic visualization of the instruments for catheterization that are passed through introducer sheath130during procedures. Under identical imaging conditions in a given background medium or tissue, instruments incorporating such features are seen to be qualitatively “brighter” than ultrasound image than instruments without such features, and thus more readily observed during use. This makes it easier for the user to visualize the placement and movement of the instrument, which in turn allows it to be utilized with greater safety and efficacy, particularly when the instruments for catheterization in question have sharp points or edges, or other features that could cause injury during use (for example, as is the case with respect to the beveled point of dilator150that is shown inFIGS.8C and8D).

In certain embodiments, features for improving ultrasonic visualization may include architectural modifications to the internal and/or external surfaces of instruments for catheterization (“ultrasound visualization modifications”) that are utilized in connection with a steerable introducer sheath assembly in accordance with the present disclosure. These ultrasound visualization modifications may include the introduction of one or more depressions or protrusions to the instrument for catheterization at sites for which enhanced visibility is particularly desirable. For example, ultrasound visualization modifications may include one or more punctate depressions or protrusions that generally appear as a cluster of “dots”, which may be irregularly scattered, or grouped and arranged in a certain regular configuration. Ultrasound visualization modifications may also include one or more linear grooves or ridges that extend in a perpendicular, parallel, angular, or spiral fashion with respect to the longitudinal center axis of the modified instrument.

In certain embodiments, ultrasound visualization modifications may be exclusively introduced to the interior surfaces of instruments for catheterization that are utilized in connection with a steerable introducer sheath assembly in accordance with an embodiment of the present disclosure. Placing the ultrasound visualization modifications on interior instrument surfaces allows the external instrument surfaces to be kept smooth and free of irregularities, and thereby helps to prevent damage or undesirable alterations to the surrounding tissue that might be caused by external irregularities during the introduction, manipulation, and/or withdrawal of instruments for catheterization having external ultrasound visualization modifications. Limiting ultrasound visualization modifications to interior instrument surfaces likewise prevents such modifications from themselves becoming altered or reduced in effectiveness through contact with potentially-damaging surfaces, and further protects against structural damage or functional inhibition that could sustained by elements of the steerable introducer sheath assembly of the present disclosure because of contact with modified external instrument surfaces (including, for example damage to the introducer sheath and/or the centralized “device” lumen through which the instrument for catheterization is passed).

Ultrasound visualization modifications may include any physical or structural alteration to an instrument that causes a subjective or objective improvement in the ultrasonic visibility of the modified instrument in comparison to an unmodified instrument. Subjective improvements may include a “brighter” or otherwise more distinct appearance for a modified instrument that is visualized using ultrasound, when compared to an unmodified instrument visualized under the same conditions. For example, as further discussed belowFIG.10Bdepicts ultrasonic images of the distal tip of a dilator having improved visualization features in accordance with embodiments of the present disclosure (bottom left and right images), which appear qualitatively “brighter” relative to the distal tip of a prior art dilator (top left and right images) viewed under the same conditions in the same background medium. Given this, a qualitative improvement in the ultrasonic visibility of an instrument with ultrasound visualization modifications according to the present disclosure may be confirmed using any of the known methods for obtaining and analyzing the subjective observations of persons who have examined and compared the subjective appearance of test objects viewed using comparable ultrasonic techniques and conditions (e.g., M. A. McCulloch, et al. Limitations of Echocardiographic Periarterial Brightness in the Diagnosis of Kawasaki Disease, 18 JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY 768-770 (2005). For example, a series of ultrasound imaging sessions may be taken of both (i) instruments having ultrasound visualization modifications according to the present disclosure, and (ii) instruments without such modifications, as they are inserted into, manipulation within, and withdrawn from a standardized tissue or test medium. Video clips of these imaging sessions may then be randomly compiled (with any potentially-identifying information removed or obscured), and independently reviewed by technically experienced individuals (e.g., interventional radiologists, ultrasound technicians, cardiologists or other specialist physicians that have experience with using the instrument in question, etc.) who are asked to grade the qualitative “brightness” or “distinctness” of each instrument so imaged. The reviewer grades are collated and processed, and statistical methods such as Cohen's kappa coefficient and the Wilcoxon rank-sum test are applied to confirm whether the instruments with ultrasound visualization modifications appear subjectively “brighter” or more distinct than the instruments without such modifications.

A relative improvement in ultrasound visualization may be also be determined by using known methods for quantifying and comparing the ultrasound signals returned by modified and unmodified instruments, including signal processing and measurement techniques designed to extract information from ultrasound echo signals that are returned from control and test articles. For example, D. Dalecki et al. recently identified and described some exemplary “[h]igh-frequency quantitative ultrasound techniques, including elastography, [that] provide metrics for quantitative assessment of structural, biological, and mechanical properties of engineered constructs” (D. Dalecki et al., Quantitative Ultrasound for Nondestructive Characterization of Engineered Tissues and Biomaterials, 44 ANN. BIOMED. ENG'G, 636-648 (2016). The use of such techniques may be further optimized by implementing computer-assisted diagnostic methods, including for example machine-learning algorithms like those used by J. Y. Wu et al. “to train classifiers and label images as normal versus abnormal based on the identified features of the images” (J. Y. Wu, et al., Quantitative analysis of ultrasound images for computer-aided diagnosis, 3 J. MED. IMAGING, 014501-1-014501-9 (2016)). To this regard, a number of commercially-available software packages may be used with commercial ultrasound systems to identify, isolate, and quantify a variety of image characteristics. For example, the QLAB Advanced Quantification Software available from Philips Medical Systems may be used in conjunction with commercial ultrasound systems to facilitate the echocardiographic analysis of structure and function (I. S. Salgo, Clinical benefits of QLAB software for advanced 2D and 3D echo quantification, Koninklijke Philips Electronics N.V. (2006)).

Given the quantitative tools and methods described above (as well as other quantitative tools and methods that are likewise known in the art), a quantitative improvement in the ultrasonic visibility of an instrument with ultrasound visualization modifications may be confirmed by first obtaining ultrasound imaging sessions of both (i) instruments having ultrasound visualization modifications according to the present disclosure, and (ii) instruments without such modifications, as they are inserted into, manipulation within, and withdrawn from a standardized tissue or test medium. For qualitative analysis, both the video clips of these imaging sessions and the underlying acoustic information that is used to form the image is extracted for analysis by a technically experienced scientist or clinician. For example, the analyst may begin by defining a region of interest (ROI) that contains the portion of the instrument that has received ultrasound visualization modifications, possibly doing so at defined locations within the standardized tissue or test medium, or at pre-defined times (for example, defining one ROI for each of the three phases of the experiment (insertion into, manipulation within the standardized tissue or test medium. Having defined the ROI, the analyst may isolate the acoustic information that underlies the image that is circumscribed by the ROI, using a technique that is known as densitometry. Having thereby isolated the raw acoustic information that underlies ROIs that correspond to the relevant portion of the instrument (i.e. the portion in which ultrasound visualization modifications were either added or not added), and this raw acoustic information may then be processed to provide a quantitative assessment of structural, biological, and mechanical properties of those instruments for catheterization that received ultrasound visualization modifications, and compare them with those instruments for catheterization that did not receive such modifications. These tests are collated and processed, and statistical methods such as Cohen's kappa coefficient and the Wilcoxon rank-sum test are applied as necessary to confirm whether, compared to instruments that do not have ultrasound visualization modifications, the instruments that do have ultrasound visualization modifications are quantitatively “brighter,” more distinct, or quantitatively improved with respect to some other visual characteristic that is reflected in the isolated acoustical data.

As noted above, ultrasound visualization modifications may include one or more punctate depressions or protrusions that generally appear as a cluster of “dots”, or as one or more linear grooves or ridges that extend in a perpendicular, parallel, angular, or spiral fashion with respect to the longitudinal center axis of the modified instrument for catheterization. Linear grooves for improving ultrasound visualization may be either continuous, or comprised of smaller segments (which themselves may be either joined in a continuous end-to-end fashion, or somewhat separated but still forming a groove that is observably linear). For example,FIG.10A, depicts a dilator (1920) for catheterization with a steerable introducer sheath assembly of the present disclosure, with said dilator having a distal opening of 0.033 inches, with said opening increasing as the dilator extends in a proximal direction to a maximum internal bore diameter of at least 0.057 inches (note thatFIG.10Aprovides a representative depiction of dilator1920that is not to scale). As shown inFIG.10A, dilator embodiment (1920) has been modified to improve ultrasound visualization through the introduction of three longitudinal grooves (1906) to the internal bore surface (1907) near the distal tip (1908), with said grooves sited 120 degrees apart from one another in a radial manner about the internal bore (as best shown inFIG.10A, upper left inset), and extending parallel to each other in a stepped fashion, in a distal-to-proximal direction that is also parallel to longitudinal axis102(as best shown inFIG.10A). Each of the three grooves introduced to dilator1920has a groove width (1909) of 0.012 inches and a total groove length (1910) of 0.375 inches, which is further subdivided into six equal steps joined end-to end, with each step having a groove step length (1911) of 0.0625 inches, and a groove step depth (1912) of 0.003 inches (as best shown inFIG.10A(main body and top right inset).

Inclusion of ultrasound visualization modifications similar to those shown inFIG.10Afacilitates visualization of instruments for catheterization during procedures conducted using ultrasonic imaging. This can be seen inFIG.10B, which depicts ultrasonic images obtained during the introduction (top left) and removal (top right) of prior art dilators (which do not contain ultrasound visualization modifications), and ultrasonic images obtained during the introduction (bottom left) and removal (bottom right) of the dilator (1920) that is illustrated inFIG.10A(which includes ultrasound visualization modifications in the form of the stepped grooves that were described above). In comparison to the appearance of the distal dilator tips indicated inFIG.10Bby arrows1910and1911, (from prior art dilators), the appearance of the distal dilator tips indicated by arrows1912and1913(from the dilator with the “stepped groove” ultrasound visualization modifications depicted inFIG.10Aand discussed herein) shows a marked increase in brilliance, which is observable as a series of parallel “streaks” that extend downward from the apparent position of the distal tip. This increased brilliance in turn facilitates visualization of the dilator's distal tip during procedures conducted using ultrasonic imaging.

In certain embodiments, dilator159may also incorporate a barium impregnated polymer that may enhance fluoroscopic visibility of dilators when introduced, for example, using a steerable introducer sheath assembly in accordance with an embodiment of the present disclosure.