CN110152162B

CN110152162B - Improved steerable introducer sheath assembly

Info

Publication number: CN110152162B
Application number: CN201810146156.9A
Authority: CN
Inventors: J·E·萨拉比亚
Original assignee: 510 Kardiac Devices Inc
Current assignee: Hangzhou Qiming Medical Devices Co ltd
Priority date: 2018-02-12
Filing date: 2018-02-12
Publication date: 2022-07-01
Anticipated expiration: 2038-02-12
Also published as: CN110152162A

Abstract

An introducer sheath assembly having: a handle portion including a distal end and a proximal end; and an introducer sheath extending outwardly from the distal end of the handle portion, the introducer sheath including a a device lumen configured to slidably receive a corresponding device, a guidewire lumen configured to slidably receive a corresponding guidewire, and disposed radially outward from the device lumen At least one steering cable is disposed within the at least one steering cable lumen, and the handle portion includes at least one steering assembly for modifying tension of at least one of the at least one steering cable.

Description

Improved steerable introducer sheath assembly

Technical Field

The present disclosure relates generally to medical devices and, more particularly, to vascular access sheaths and catheters.

Background

Increasingly, minimally invasive catheter-based therapies are being developed that allow physicians to provide therapy to patients: the patients' existing comorbidity may prevent them from performing the required but more invasive surgical procedure. Over the past 30 years, catheter-based procedures involving piercing/traversing the atrial septum (such as cardiac ablation and balloon valvuloplasty) have become commonplace. New structure cardiac surgery (such as transcatheter valve repair/replacement and left atrial appendage closure) has gained regulatory acceptance over the last 5 to 10 years and has become an increasingly common procedure performed in cardiac catheterization laboratories or hybrid operating rooms. With the advent of these techniques, there is an increasing need for structural cardiac interventionalists (specialized physicians performing these types of procedures) to engage and traverse the interatrial septum in the heart.

Historically, due to the prevalence of cardiac ablation procedures that require crossing the interatrial septum, crossing the septum has been within the capabilities of pediatric cardiologists or electrophysiologists. However, interventional cardiologists are increasingly beginning to provide treatments to the left side of the heart, and the need to pierce the interatrial septum and provide these new treatments is increasing. Unfortunately, many of these interventional cardiologists do not perform transseptal punctures with sufficient regularity to become proficient at this. For these left-side procedures, it is not sufficient to safely puncture the interatrial septum and access the left side of the heart. These new techniques require a very specific and safe location when traversing the interatrial septum. Furthermore, crossing the interatrial septum has historically been guided by fluoroscopy (X-ray) and more recently by echocardiography (intracardiac echocardiography, transesophageal echocardiography or transthoracic echocardiography). Fluoroscopy is limited in its effectiveness because of its limited ability to image soft tissue, such as the interatrial septum. Therefore, guiding these types of procedures is increasingly relying on echocardiography.

As such, it is desirable to provide these newly grown structural cardiac interventions with tools to help them safely and accurately traverse the interatrial septum. Preferably, these tools may have features that facilitate accurate positioning of vascular sheaths, catheters, and other instruments for catheter-based therapies, including transseptal procedures. These tools may also include features that may increase their utility with respect to echocardiography, and may enhance echocardiography information or facilitate certain modalities of echocardiography to be used for image guidance that may not otherwise be useful.

The present invention recognizes and addresses problems of prior art constructions and methods.

Disclosure of Invention

An introducer sheath assembly, comprising: a handle portion including a distal end and a proximal end; an introducer sheath extending outwardly from the distal end of the handle portion, the introducer sheath including an instrument lumen configured to slidably receive a corresponding instrument, first, second, and third steering cable lumens, and a first steering cable attached at the distal end of the introducer sheath and disposed within the first steering cable lumen, a second steering cable attached at the distal end of the introducer sheath and disposed within the second steering cable lumen, and a third steering cable attached at the distal end of the introducer sheath and disposed within the third steering cable lumen, wherein the first, second, and third steering cable lumens are disposed radially outwardly from the instrument lumen, wherein the first and second steering cable lumens are positioned in a vertical plane extending through the instrument lumen and the third cable lumen On opposite sides of the face; a first steering assembly disposed within the handle portion, the first steering assembly including an element to which a proximal end of the first steering cable is attached and an element to which a proximal end of the second steering cable is attached; a first steering lever disposed on an exterior surface of the handle portion and attached to a first end of a first steering column, wherein the first steering column has a second end engaged with the first steering assembly such that rotating the steering lever about a longitudinal axis of the first steering column causes the first steering assembly to simultaneously modify tension in the first steering cable and the second steering cable; a second steering assembly disposed within the handle portion, a proximal end of the third steering cable being attached to the second steering assembly; and a second steering lever disposed on an exterior surface of the handle portion and attached to a first end of a second steering column, wherein the second steering column has a second end that engages the second steering assembly such that rotating the steering lever about a longitudinal axis of the second steering column causes the second steering assembly to modify the tension in the third steering cable.

Another embodiment of an introducer sheath assembly according to the present disclosure comprises: a handle portion having a distal end and a proximal end; an introducer sheath extending outwardly from the distal end of the handle portion, the introducer sheath including an equipment lumen configured to slidably receive a corresponding equipment, a first steering cable lumen, a second steering cable lumen, and a third steering cable lumen, and a first steering cable attached at the distal end of the introducer sheath and disposed within the first steering cable lumen, a second steering cable attached at the distal end of the introducer sheath and disposed within the second steering cable lumen, a third steering cable attached at the distal end of the introducer sheath and disposed within the third steering cable lumen, and a fourth steering cable attached at the distal end of the introducer sheath and disposed within the fourth steering cable lumen, wherein the first steering cable lumen, the second steering cable lumen, the third steering cable lumen, the fourth steering cable lumen, the steering cable lumen, and the steering cable lumen, The third and fourth steering cable lumens are disposed radially outward from the device lumen, wherein the first and second steering cable lumens are positioned on opposite sides of a vertical plane in which the longitudinal central axis of the introducer sheath lies, and the third and fourth steering cable lumens are positioned on opposite sides of a horizontal plane in which the longitudinal central axis of the introducer sheath lies; a first steering assembly disposed within the handle portion, the first steering assembly including an element to which a proximal end of the first steering cable is attached and an element to which a proximal end of the second steering cable is attached; a second steering assembly disposed within the handle portion, the second steering assembly including an element to which a proximal end of the third steering cable is attached and an element to which a proximal end of the fourth steering cable is attached; wherein the first steering assembly is manipulable to simultaneously modify tension in the first steering cable and the second steering cable, and the second steering assembly is manipulable to simultaneously modify tension in the third steering cable and the fourth steering cable.

Another embodiment of an introducer sheath assembly according to the present disclosure comprises: a handle portion having a distal end and a proximal end; an introducer sheath extending outwardly from the distal end of the handle portion, the introducer sheath including an device lumen configured to slidably receive a corresponding device, at least one steering cable lumen disposed radially outwardly from the device lumen, at least one steering cable attached at the distal end of the introducer sheath, disposed within the at least one steering cable lumen, and engaged with a steering assembly disposed within the handle portion; one or more steering levers disposed on the exterior surface of the handle portion and attached to a first end of a steering column, wherein said steering column has a second end that engages a steering assembly such that rotating the steering lever about the longitudinal axis of the steering column causes the steering assembly to modify the tension in said at least one steering cable; and wherein at least one steering lever directly or indirectly engages a surface of the handle portion in a manner that limits the extent to which the steering lever can be rotated about the longitudinal axis of the steering column.

Another embodiment of an introducer sheath assembly according to the present disclosure comprises: a handle portion having a distal end and a proximal end; an introducer sheath extending outwardly from the distal end of the handle portion, the introducer sheath including an device lumen configured to slidably receive a corresponding device, at least one steering cable lumen disposed radially outwardly from the device lumen, at least one steering cable attached at the distal end of the introducer sheath, disposed within the at least one steering cable lumen, and engaged with a steering assembly disposed within the handle portion; one or more steering levers disposed on an exterior surface of the handle portion and attached to a first end of a steering column, wherein the steering column has a second end that engages a steering assembly such that rotating the steering lever about a longitudinal axis of the steering column causes the steering assembly to modify tension in the at least one steering cable; and wherein the engagement between at least one steering lever and the outer surface of the handle portion is mediated by a dome at least partially surrounding the steering lever, wherein said dome is seated in a correspondingly shaped recess in the outer surface of the handle.

Another embodiment of an introducer sheath assembly according to the present disclosure comprises: a handle portion having a distal end and a proximal end; an introducer sheath extending outwardly from the distal end of the handle portion, the introducer sheath including an device lumen configured to slidably receive a corresponding device, at least two steering cable lumens disposed radially outwardly from the device lumen, at least two steering cables attached at the distal end of the introducer sheath and disposed within the at least two steering cable lumens; a first steering assembly disposed within the handle portion, the first steering assembly including an element to which a proximal end of at least one of the at least two steering cables is attached; and a second steering assembly disposed within the handle portion, the second steering assembly including an element to which a proximal end of at least one of the at least two steering cables is attached; wherein the first steering assembly is manipulable to modify tension in a steering cable attached thereto and the second steering assembly is manipulable to modify tension in a steering cable attached thereto; and a slack removal assembly to remove excess slack from at least one of the steering cables attached to at least one of the steering assemblies when the other steering assembly is manipulated to modify tension in at least one of its attached steering cables.

Another embodiment of an introducer sheath assembly according to the present disclosure comprises: a handle portion having a distal end and a proximal end; an introducer sheath extending outwardly from the distal end of the handle portion, the introducer sheath including a device lumen configured to slidably receive a corresponding device; a device locking assembly disposed at the rear end of the housing portion, the device locking assembly comprising: an equipment locking rod defining an axially extending bore certified to slidably receive the corresponding equipment, the equipment locking rod being axially movable relative to the handle portion; a clamp disposed on the equipment locking rod, the clamp being selectively positioned in a locked position in which the corresponding equipment is axially fixed relative to the equipment locking rod and an unlocked position in which the corresponding equipment is slidable within the axially extending bore of the equipment locking rod; wherein the instrument locking assembly further comprises an advancement knob axially fixed and rotatable relative to the handle portion of the body portion, wherein the advancement knob further comprises a threaded bore correspondingly threadedly coupled to an exterior surface of the instrument locking lever, the instrument locking lever threadably coupled to the threaded bore of the advancement knob; and wherein the device locking lever is further engaged with a lever guide disposed within the handle portion to prevent rotation of the locking lever when the knob is rotated. Such embodiments may also include features to facilitate injection molding manufacturing techniques, including parallel, interrupted flats in external threads on the exterior surface of the device locking bar, and the advancement knob further characterized by outwardly depending members that collectively define a discontinuous radial flange having a radius greater than a radius of a distal aperture in the handle portion, wherein the discontinuous radial flange allows the advancement knob to be rotatably disposed and retained within the distal aperture in the handle portion, wherein the flanges are mirrored by an opening through the advancement knob.

Another embodiment of an introducer sheath assembly according to the present disclosure comprises: a handle portion having a distal end and a proximal end; an introducer sheath extending outwardly from the distal end of the handle portion, the introducer sheath including an device lumen configured to slidably receive a corresponding device, at least one steering cable lumen disposed radially outwardly from the device lumen, at least one steering cable attached at the distal end of the introducer sheath, disposed within the at least one steering cable lumen, and engaged with a steering assembly disposed within the handle portion, wherein the steering assembly is capable of modifying tension within the at least one steering cable; and a torque transmission lock that prevents rotation of the introducer sheath about the longitudinal central axis when the steering assembly is used to modify tension in the at least one steering cable. The torque-transmitting lock may also include a hollow cylinder having an inner diameter sufficient to surround the radial diameter of the introducer sheath, and at least one proximal structure engageable with at least one corresponding structure extending from a face of the handle portion.

Another embodiment of an introducer sheath assembly according to the present disclosure comprises: a handle portion including a distal end and a proximal end; an introducer sheath extending outwardly from the distal end of the handle portion, the introducer sheath including a device lumen configured to slidably receive a corresponding device; and an aperture in the handle portion that allows a user to visualize the point at which the corresponding device has been received into the device lumen of the introducer sheath, and may further include a corresponding device containing indicia that can be visualized through the aperture to provide an indication to a user of the extent to which the corresponding device has been inserted into the device lumen of the introducer sheath.

Another embodiment of an introducer sheath assembly according to the present disclosure comprises: a handle portion having a distal end and a proximal end; an introducer sheath extending outwardly from the distal end of the handle portion, the introducer sheath including a device lumen configured to slidably receive a corresponding device; wherein the corresponding apparatus comprises one or more modifications that improve ultrasound visualization. In certain such embodiments, the corresponding apparatus is a dilator having a hollow axial bore, the dilator containing modifications to improve ultrasound visualization, and the modifications being located on an interior surface of the hollow axial bore. For example, such a dilator may include at least one linear groove extending in a parallel manner with respect to a longitudinal central axis of the dilator, and by yet another example may include at least one linear groove having a width of about 0.012 inches and a depth of up to about 0.003 inches, wherein the groove has a total length of about 0.375 inches in certain embodiments, and consists of a continuous step having a length of about 0.0625 inches in certain other embodiments.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and together with the description, serve to explain the principles of the invention.

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

fig. 1A is a top perspective view of a steerable introducer sheath assembly according to one embodiment of the present disclosure;

fig. 1B provides top, bottom, and side views of a handle portion of a steerable introducer sheath assembly according to one embodiment of the disclosure;

fig. 1C provides a top view of a steerable introducer sheath assembly according to one embodiment of the present disclosure;

fig. 1D provides a side view of a steerable introducer sheath assembly according to one embodiment of the present disclosure;

fig. 2A is a partial bottom view of a handle portion of a steerable introducer sheath assembly with a bottom portion of a handle housing removed to allow visualization of internal elements, according to one embodiment of the present disclosure;

fig. 2B provides a distal, a back, a side and a perspective view of the distal end cap of the steerable introducer sheath assembly according to one embodiment of the present disclosure;

fig. 2C provides a distal, posterior and perspective view of an advancement knob of a steerable introducer sheath assembly in accordance with one embodiment of the present disclosure;

fig. 2D is a partial bottom view of a handle portion of a steerable introducer sheath assembly with a bottom portion of the handle housing removed to allow visualization of internal elements, according to one embodiment of the present disclosure;

fig. 3A provides a cross-sectional view of a "four lumen" introducer sheath for use with a steerable introducer sheath assembly according to one embodiment of the present disclosure;

fig. 3B provides a cross-sectional view of a "five lumen" introducer sheath for use with a steerable introducer sheath assembly according to one embodiment of the present disclosure;

fig. 4A provides an exploded view of a torque-transmitting lock for use with a steerable introducer sheath assembly in accordance with an embodiment of the present disclosure;

fig. 4B provides a cross-sectional view of a torque-transmitting lock for use with a steerable introducer sheath assembly in accordance with an embodiment of the present disclosure;

fig. 5A provides a perspective view and a cross-sectional view of a handle portion of a steerable introducer sheath assembly in accordance with one embodiment of the present disclosure, with the inset showing additional cross-sectional detail and depicting the steering lever 160 in an "unlocked" position;

fig. 5B provides a perspective view and a cross-sectional view of a handle portion of a steerable introducer sheath assembly in accordance with one embodiment of the present disclosure, with the inset showing additional cross-sectional detail and depicting the steering lever 160 in a "locked" position;

fig. 5C provides a cross-sectional view of the interior faces of the upper and lower portions of the handle of the steerable introducer sheath assembly according to one embodiment of the present disclosure;

fig. 5D provides a top view and a perspective view of a handle of a steerable introducer sheath assembly with a steering lever and associated dome separated and/or rotated relative to the handle according to one embodiment of the present disclosure;

fig. 6A provides top, bottom, and side views of a handle portion of a steerable introducer sheath assembly according to one embodiment of the present disclosure;

fig. 6B provides a perspective view of a handle of a steerable introducer sheath assembly with elements of the distal housing portion separated to aid in visualization of certain features in accordance with an embodiment of the present disclosure;

fig. 6C provides a top view of a steerable introducer sheath assembly according to one embodiment of the present disclosure;

fig. 6D provides a side view of a steerable introducer sheath assembly according to one embodiment of the present disclosure;

fig. 7A provides a perspective view of a handle portion of a steerable introducer sheath assembly with a portion of the handle housing removed to allow visualization of the slack elimination assembly in a slack configuration (top image) and a slack removal configuration (bottom image) according to one embodiment of the present disclosure;

FIG. 7B provides an isolated view of the upper handle portion (left), an isolated view of the isolated slack elimination assembly in a slack removal configuration (middle), and an isolated view of the isolated slack elimination assembly in a rest configuration (right), according to one embodiment of the present disclosure;

fig. 8A is a top perspective view of a handle portion of a steerable introducer sheath assembly according to one embodiment of the present disclosure.

Fig. 8B is a side perspective cross-sectional view of a handle portion of a steerable introducer sheath assembly according to one embodiment of the present disclosure;

fig. 8C is a side perspective cross-sectional view of the proximal end of the handle portion of the steerable introducer sheath assembly shown in fig. 8B;

fig. 8D is a side perspective cross-sectional view of a proximal end of a handle portion of a steerable introducer sheath assembly in accordance with an embodiment of the present disclosure;

fig. 8E provides a perspective view of a device locking lever from the handle portion of a steerable introducer sheath assembly in accordance with an embodiment of the present disclosure;

fig. 9A provides a detailed view of the distal end of a steerable introducer sheath assembly with a portion of the handle housing removed to allow visualization of the internal elements, according to one embodiment of the present disclosure;

fig. 9B is a cross-sectional view of the proximal end of the handle portion of a steerable introducer sheath assembly according to an embodiment of the present disclosure, as viewed from a distal perspective;

fig. 9C is a top perspective view of an engagement site between a device locking rod and an inner guide member for use with a steerable introducer sheath assembly in accordance with an embodiment of the present disclosure;

fig. 10A provides a cross-sectional view of a dilator instrument for use with a steerable introducer sheath assembly according to one embodiment of the present disclosure; and

fig. 10B provides ultrasound images obtained during introduction (top left) and removal (top right) of a prior art dilator, and ultrasound images obtained during introduction (bottom left) and removal (bottom right) of a dilator according to one embodiment of the present invention.

Repeat 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 present disclosure.

Detailed Description

Reference will now be made in detail to certain embodiments of the invention, examples of which are illustrated in the accompanying drawings. These embodiments are provided by way of example and should not be construed to limit 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, can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

In the description of the steerable introducer sheath embodiments provided herein, the terms "distal" and "proximal" will be used to describe movement and relative position. As can be seen in fig. 1A-1D, the term "distal" refers to relative position and/or movement in the direction of the terminal end 136 of the introducer sheath 130 (i.e., in the direction of the patient), and "proximal" refers to relative position and/or movement in the direction of the device lock assembly 192 (i.e., in the direction of the user).

Within the scope of this specification the term "about" should be interpreted as +/-10%.

Steerable introducer sheath assemblies employing the present disclosure include an introducer sheath portion extending in a distal manner from a handle portion that can be grasped and manipulated by a user. One or more steering cables are attached to the distal end of the introducer sheath, passing proximally through a longitudinal steering cable lumen within the introducer sheath to the interior of the handle portion, wherein the proximal ends of the steering cables are engaged with at least one mechanism that allows a user to manipulate the distal end of the introducer sheath by selectively increasing or decreasing steering cable tension. The precise location at which the distal end of the steering cable is attached at or near the distal tip of the introducer sheath can be varied proximally or distally as necessary to provide the desired amount of distal bend modification when increasing or decreasing steering cable tension. The introducer sheath portion also includes a longitudinal device lumen capable of slidably receiving a catheterization instrument, which may include a dilator (e.g., as depicted in fig. 8C and 8D), through which a standard length baylis RF transseptal device (available from baylis Medical, montreal, canada), a Brockenbrough transseptal needle, or other similar instrument is passed. The handle portion also includes features that allow a user to finely control the advancement of the catheter-inserted instrument through the introducer sheath.

Fig. 1A and 3A illustrate exemplary features of a steerable introducer sheath assembly according to one embodiment of the present disclosure. As best shown in fig. 1A, the steerable introducer sheath assembly can include a handle portion 110 and an introducer sheath 130 extending outwardly from a distal end (116) of the handle portion 110. As best shown in fig. 3A (depicting a planar cross-section of the introducer sheath 130 perpendicular to the longitudinal central axis 102), the introducer sheath 130 can contain: a substantially centrally located device lumen 140, the device lumen 140 configured to slidably receive a catheterization instrument (e.g., dilator 159 shown in fig. 8A and 8C and discussed herein); a first steering cable lumen 146 and a second steering cable lumen 148 within which a first steering cable 154 and a second steering cable 156 (respectively) are slidably disposed; and a third steering cable lumen 150, a third steering cable 158 slidably disposed within the third steering cable lumen 150.

Referring again to the introducer sheath depicted in fig. 3A, the first steering cable lumen 146 and the second steering cable lumen 148 may be disposed on opposite sides of the device lumen 140 along a horizontal plane formed by the horizontal axis 104 and the longitudinal central axis 102, and are symmetrical about a vertical plane formed by the vertical axis 103 and the longitudinal central axis 102, wherein the horizontal plane and the vertical plane are perpendicular to each other. In this way, the horizontal bending of the distal portion 132 of the introducer sheath to the left or right of the vertical plane is adjusted by adjusting the tension in the first and

second steering cables

154, 156 while minimizing potential unintended movement within the vertical plane. As further depicted in fig. 3A, the third steering cable lumen 150 and the device lumen are arranged along the vertical plane, with the third steering cable lumen 150 being arranged above the device lumen 140 (i.e., closer to a user viewing the steerable introducer sheath from the "top" view illustrated in fig. 1C). In this way, adjusting the tension on the third steering cable 158 adjusts the "vertical" bending of the distal portion 132 of the introducer sheath 130 in this vertical plane while minimizing any undesired deflection of the introducer sheath 130 to the left or right of this vertical plane. In other words, when an operator views the sheath assembly 100 from the proximal handle portion 110 and looks distally along the introducer sheath 130, with the introducer sheath 130 extending outwardly in an undeflected position, the "horizontal" bending of the distal portion 132 of the introducer sheath 130 to the left and right of the axis 102, respectively, can be accomplished with the first and second steering cables 154 and 156 (as best shown in fig. 1C), and the amount of "vertical" bending of the distal portion 132 of the introducer sheath 130 can be adjusted with the third steering cable 158 to lift the distal portion 132 "up" (i.e., toward the user) from the axis 102 (as best shown in fig. 1D).

Other embodiments of steerable introducer sheath assemblies of the present disclosure can include an introducer sheath as depicted in fig. 3B (depicting a planar cross-section of the introducer sheath 1300 perpendicular to the longitudinal central axis 102) containing: a substantially centrally located device lumen 1400, the device lumen 1400 configured to slidably receive a catheterization instrument (e.g., the dilator 159 shown in fig. 8A and 8C and discussed herein); a first steering cable lumen 1460 and a second steering cable lumen 1480 within which a first steering cable 1540 and a second steering cable 1560 are slidably disposed (respectively); and a third steering cable lumen 1500 and a fourth steering cable lumen 1420, within which the third steering cable 1580 and the fourth steering cable 1520 (respectively) are slidably disposed. As further depicted in fig. 3B, the first and second

steering cable lumens

1460, 1480 are disposed on opposite sides of the apparatus lumen 1400 along a horizontal plane formed by the horizontal axis 104 and the longitudinal central axis 102 and are symmetrical about a vertical plane formed by the vertical axis 103 and the longitudinal central axis 102, wherein the horizontal plane and the vertical plane are perpendicular to each other. The third steering cable lumen 1500 and the fourth steering cable lumen 1420 are disposed on opposite sides of the apparatus lumen 140 along a vertical plane formed by the vertical axis 103 and the longitudinal center axis 102, and are symmetrical about a horizontal plane formed by the horizontal axis 104 and the longitudinal center axis 102.

For introducer sheaths having the cable arrangement shown in fig. 3B, the "horizontal" bending of the distal portion of the introducer sheath in the direction of the horizontal axis 104 (i.e., to the left or right of the vertical plane) is modified by adjusting the tension in the first and

second steering cables

1540 and 1560. This is best shown in fig. 6C, which fig. 6C depicts an introducer sheath 1300 with a "horizontal" bend to the left of the vertical plane (fig. 6C, left), an introducer sheath 1300 without a "horizontal" bend (fig. 6C, center), and an introducer sheath 1300 with a "horizontal" bend to the right of the vertical plane (fig. 6C, right). Similarly, adjusting the tension in the third steering cable 1580 and the fourth steering cable 1520 modifies the "vertical" bending of the distal portion of the introducer sheath in the direction of the vertical axis 103 (i.e., bending above or below the horizontal plane). This is best shown in fig. 6D, which fig. 6D depicts the introducer sheath 1300 with a "vertical" bend below the horizontal plane (fig. 6D, left), the introducer sheath 1300 without a "vertical" bend (fig. 6D, center), and the introducer sheath 1300 with a "vertical" bend above the horizontal plane (fig. 6D, right).

The handle portion of a steerable introducer sheath assembly according to one embodiment of the present disclosure includes features that allow a user to selectively increase or decrease steering cable tension to achieve a desired "horizontal" bend or "vertical" bend of the distal portion of the introducer sheath. As best illustrated in fig. 1B-1D, for example, the handle portion 110 may include: a steering lever 160 for adjusting tension in the first and second steering cables in order to modify a "horizontal" bend of the distal portion 132 of the introducer sheath 130 (as best depicted in fig. 1C and discussed further below); and a distal end cap 180 for adjusting tension in the third steering cable so as to modify the "vertical" bend of the distal portion 132 of the introducer sheath 130 (as best depicted in fig. 1D and discussed further below).

In certain embodiments, the mechanism for manipulating the first and

second steering cables

154 and 156 to adjust the amount of "horizontal" bending of the distal portion 132 of the introducer sheath may include an external steering lever 160 that controls the internal system of drive gears and spin columns coupled to the

steering cables

154 and 156. As best illustrated in fig. 2A, 5A, and 5B, for example, the steering lever 160 may be pivotally secured to the first end of the steering column 164 through an aperture aligned to receive the steering lever pin 198. Steering column 164 is non-rotatably fixed at a second end thereof to a drive gear 166. The drive gear 166 is positioned within the handle 100 to enable simultaneous engagement and rotation of the first and

second gear assemblies

168, 174. As best shown in fig. 2A, the first and

second gear assemblies

168, 174 may each include a rotatable post (126, 128) extending inwardly from the housing on the interior of the handle 100, a non-rotatably fixed barrel portion (172, 178), and a non-rotatably fixed gear (170, 176) engaging the drive gear 166. The

posts

126 and 128 may be positioned perpendicular to the central axis 102 (e.g., as depicted in fig. 2A, 5A, and 5B), or alternatively at a non-perpendicular angle to the central axis 102. The

posts

126 and 128 may be rotationally engaged by retention features extending inwardly from the interior surfaces of the upper housing portion 112, the lower housing portion 114, or both. For example, as best shown in fig. 5C (depicting the base flange and showing engagement of the post 126 with the base flange 1914 in the lower housing portion 114), in some embodiments, the

posts

126 and 128 may be rotationally engaged by circular base flanges 1914 within the upper and

lower housing portions

112 and 114.

As briefly mentioned above and best illustrated in fig. 1A and 2A, the distal ends of the first steering cable 154 and the second steering cable 156 are attached at or near the distal tip 136 of the introducer sheath, with the cables themselves extending proximally (respectively) through the steering

lumens

146 and 148 until the proximal ends terminate in the interior of the handle portion 110, wherein the proximal ends of the two cables may be engaged by one or more steering mechanisms that can selectively increase or decrease tension in the steering cables.

For example, as best shown in fig. 2A, the first and

second steering cables

154 and 156 may exit the introducer sheath 130 via

respective openings

1960 and 1961 that are located near terminal portions of the introducer sheath 130 (i.e., portions that are located inside the handle portion 110). In this manner, the proximal ends of the first and

second steering cables

154 and 156 can exit from the steering lumens 146 and 148 (respectively) and engage the first and second steering gear assemblies 168 and 174 (respectively). For embodiments of the steerable introducer sheath assembly of the present disclosure that include an introducer sheath similar to introducer sheath 1300 shown in fig. 3B, the proximal ends of the first and

second steering cables

1540 and 1560 exit from the first and second steering cable lumens 1460 and 1480 (respectively) via openings similar to the openings shown in fig. 2A (1960 and 1961), and engage with the first and second steering gear assemblies 168 and 174 (respectively).

As best shown in fig. 2A, for example, in some embodiments, the proximal end of the first steering cable 154 is attached to a barrel portion 172 of the first gear assembly 168, and the proximal end of the second steering cable 156 is attached to a barrel portion 178 of the second gear assembly 174. Drive gear 166 is engaged with first and

second gears

170 and 176 such that rotation of drive gear 166 causes first and

second gear assemblies

168 and 174 to simultaneously rotate, thereby adjusting the tension applied to first and

second steering cables

154 and 156, which first and

second steering cables

154 and 156 are respectively attached to

barrel portions

172 and 178 and wrapped around

barrel portions

172 and 178 in a manner such that when the tension in one of the steering cables increases due to rotation of steering lever 160, the tension in the other steering cable decreases. In this way, the first steering cable 154 and the second steering cable 156 operate in unison to increase or decrease the "horizontal" bending of the distal portion 132 to the left or right of the axis 102.

In certain embodiments, the first and

second steering cables

154 and 156 are affixed to and engaged by the

barrel portions

172 and 178, respectively, in such a manner that rotating the steering lever 160 in a counterclockwise manner (i.e., so that the distal end of the steering lever 160 is directed more "left" relative to the longitudinal central axis 102) causes the distal portion (136) of the introducer sheath 130 to become more "horizontally" curved to the left of the longitudinal central axis 102 (fig. 1C, at the left) when viewing the handle portion 110 from a "top view" as best illustrated in fig. 1C, rotating the steering lever 160 in a clockwise manner (i.e., so that the distal end of the steering lever 160 is directed more "right" relative to the longitudinal central axis 102) causes the distal portion (136) of the introducer sheath 130 to become more "horizontally" curved to the right of the longitudinal central axis 102 (fig. 1C, at the right) and returning the steering lever 160 to the center position (i.e., such that the distal end of the steering lever 160 points in a direction parallel to the longitudinal central axis 102) causes the distal portion 136 of the introducer sheath 130 to extend in a direction parallel to the longitudinal central axis 102 (i.e., without a "horizontal" bend, as in fig. 1C, at the center). In this manner, the orientation of the distal end of the steering lever 160 can provide the user with an indication of the presence, directionality, and relative extent of any "horizontal" bends that have been introduced to the distal portion (136) of the introducer sheath 130.

In an alternative embodiment, the first and

second steering cables

154 and 156 may be attached to and engaged by the

barrel portions

172 and 178 such that turning the steering lever in a "counterclockwise" manner will cause the distal portion (136) of the introducer sheath 130 to bend horizontally to the right, and vice versa.

In certain embodiments of steerable introducer sheath assemblies according to the present disclosure, the interaction between the steering lever 160, the drive gear 166, and/or the first and

second gear assemblies

168, 174 can be modified to increase or decrease the "sensitivity" of the steering lever 160 (i.e., the degree to which "horizontal" bending is introduced when rotating the steering lever 160 to a particular degree). For example, in certain embodiments, a variable transmission may be provided that allows a user to modulate the "sensitivity" of steering lever 160 by selectively modifying the drive gear 166 and/or the gear ratio (gearing ratio) between first and

second gear assemblies

168, 174. Alternatively, a spring loaded gear column and/or flywheel assembly may be provided for modulating the sensitivity of the steering lever 160 in a desired manner.

In certain embodiments, the steerable introducer sheath assembly can include a mechanism to lock the steering lever in place once a desired amount of flexion of the introducer sheath has been achieved. As shown in fig. 5A and 5B, for example, the steering lever 160 may include a cam surface 162 such that when the steering lever 160 is rotated upward about the steering lever pin 198 from an "unlocked" position (fig. 5A) to a "locked" position (fig. 5B), the cam surface 162 becomes frictionally engaged with the outer surface of the upper handle portion 112 and lifts the steering column 164 in a radial direction away from the interior of the handle such that the drive gear 166 becomes frictionally engaged with the inner surface of the upper handle portion 112. In certain embodiments, this "locking" friction may be modulated by providing one or more washers to separate the drive gear 166 and the interior surface of the upper handle portion 112, which upper handle portion 112 may, for example, include a wave spring washer 1915 depicted in fig. 5A and 5B.

As shown in fig. 5A, 5B, and 5D, certain embodiments may include a dome 1916, the dome 1916 being seated within a dome pocket 1917 that is extruded from an exterior face of the upper handle portion 112, thereby mediating interaction between the cam surface 162 of the steering lever 160 and the exterior surface of the upper handle portion 112. As best shown in fig. 5D (inset), the dome 1916 may be shaped to provide a central slot 1917 through which the steering lever 160 protrudes, with the groove 1917 being wide enough to accommodate vertical rotation between the "unlocked" position and the "locked" position, while also providing lateral support to the steering lever 160 when the steering lever 160 is manipulated to rotate the steering column 164, and also ensuring that the steering lever 160 is constrained to a direction perpendicular to the axis of the steering lever pin 198 when pivoting from the "unlocked" position (fig. 5A) to the "locked" position (fig. 5B).

In certain embodiments, the dome 1916 and dome pocket 1917 may be configured to limit the angular displacement of the steering column 164 about its longitudinal axis when the steering lever 160 is manipulated. As shown in fig. 5D, this may be accomplished, for example, by flanges (1918 and 1919) extending from the underside of dome 1916, and may interact with a distal face formed by corresponding protrusions 1920 and 1921 (respectively) to constrain rotation of steering lever 160. This protects the

cables

154 and 156 from excessive strain that may be caused by a user attempting to over-tighten them using the steering lever 160. In some embodiments, the

protrusions

1920 and 1921 and/or the

flanges

1918 and 1919 may be adjustable such that the degree to which rotation of the steering lever 160 is limited may be modified according to a user's preference.

For embodiments of the steerable introducer sheath assembly of the present disclosure featuring an introducer sheath having the cable arrangement shown in fig. 3B, a steering lever having the steering assembly mechanism, and other associated features described above, the same can be used to adjust the tension in the first and

second steering cables

1540 and 1560 to modify the "horizontal" bending of the distal portion of the introducer sheath in the direction of the horizontal axis 104 (i.e., to the left or right of the vertical plane). For such embodiments, the first and

second steering cables

1540 and 1560 are attached to and engaged by the

barrel portions

172 and 178 in the same manner as described above for the first and

second steering cables

154 and 156 from the introducer sheath 130 (and illustrated in fig. 2A). As such, when viewed from the "top" as illustrated in fig. 1C and 6C, rotating the steering lever 160 in a counterclockwise manner (i.e., so that the distal end of the steering lever 160 is directed more "to the left" with respect to the longitudinal central axis 102) causes the distal portion (1360) of the introducer sheath 1300 to become more "horizontally" curved to the left of the longitudinal central axis 102 (fig. 6C, at the left), rotating the steering lever 160 in a clockwise manner (i.e., so that the distal end of the steering lever 160 is directed more "to the right" with respect to the longitudinal central axis 102) causes the distal portion (1360) of the introducer sheath 1300 to become more "horizontally" curved to the right of the longitudinal central axis 102 (fig. 6C, at the right), and returning the steering lever 160 to the center position (i.e., so that the distal end of the steering lever 160 is directed in a direction parallel with the longitudinal central axis 102) causes the distal portion (1360) of the introducer sheath 1300 to be more "horizontally" to the right "with the longitudinal central axis 102) The lines 102 extend in parallel directions (i.e., do not have a "horizontal" bend, as in fig. 6C, at the center). Here again, the orientation of the distal end of the steering lever 160 represents the presence, directionality, and relative degree of any "horizontal" bends that have been introduced to the distal portion (1360) of the introducer sheath 1300.

This is best shown in fig. 6C, which fig. 6C depicts an introducer sheath 1300 with a "horizontal" bend to the left of the vertical plane (fig. 6C, left), an introducer sheath 1300 without a "horizontal" bend (fig. 6C, center), and an introducer sheath 1300 with a "horizontal" bend to the right of the vertical plane (fig. 6C, right). Similarly, the "vertical" bending of the distal portion of the introducer sheath in the direction of the vertical axis 103 (i.e., bending above or below the horizontal plane) is modified by adjusting the tension in the third steering cable 1580 and the fourth steering cable 1520. This is best shown in fig. 6D, which fig. 6D depicts the introducer sheath 1300 with a "vertical" bend below the horizontal plane (fig. 6D, left), the introducer sheath 1300 without a "vertical" bend (fig. 6D, center), the introducer sheath 1300 with a "vertical" bend above the horizontal plane (fig. 6D, right).

As previously mentioned, the handle portion of a steerable introducer sheath according to one embodiment of the present disclosure can also include features that allow a user to selectively increase or decrease steering cable tension to achieve a desired "vertical" bend of the distal portion of the introducer sheath. For example, the handle portion 110 can include a distal end cap 180, the distal end cap 180 controlling axial movement of an externally threaded rod 188 to adjust tension in the third steering cable to modify the "vertical" bending of the distal portion 132, as shown in fig. 1D (at the left and center).

As can be seen in fig. 1A-1D, the handle portion 110 may include an upper housing portion 112 and a lower housing portion 114, the upper housing portion 112 and the lower housing portion 114 together defining a distal aperture 118 disposed at a distal end (116) of the handle portion 110. In certain embodiments, the distal aperture 118 may be configured to rotatably receive the distal end cap 180 such that the distal end cap 180 is free to rotate relative to the handle portion 110. For example, as illustrated in fig. 2A & 2B and 7B, the distal end cap 180 may include a plurality of ridges 182 extending radially outward from the exterior surface such that the distal end cap 180 may be easily grasped and rotated during use. The distal end cap 180 may also include an internally threaded portion 186, the internally threaded portion 186 engaging a corresponding threaded rod 188 disposed within the handle portion 110. Distal end cap 180 may also include an outwardly depending radial flange disposed at a proximal end thereof, the radial flange having a diameter greater than the diameter of distal aperture 118, thereby allowing distal end cap 180 to be received and axially retained within annular cavity 120 defined by the junction of upper housing portion 112 and lower housing portion 114 to form grip portion 110.

As best shown in fig. 2A-2B and 7B, in certain embodiments, the outwardly depending radial flange disposed at the proximal end of the distal end cap 180 may be comprised of a plurality of tabs (tab)184, the tabs 184 having outwardly depending members that together define a discontinuous radial flange having a radius greater than the radius of the distal aperture 118 such that the distal end cap 180 may be received and axially retained within the annular cavity 120. As best shown in fig. 2B, the distal end cap 180 may also include a plurality of vent holes (vents) 1850 corresponding to the tabs 184 in an arrangement that facilitates manufacturing of the distal end cap 180 using injection molding techniques.

As can be seen in fig. 4A and 4B, the externally threaded rod 188 may include one or more axially extending slots 189, which one or more axially extending slots 189 may engage one or more axially extending flanges 129 depending radially inward from the interior surface of the handle 110. When the distal end cap 180 is rotated, the engagement of the slot 189 and the flange 129 ensures that the externally threaded rod 188 also does not rotate, with the result that the externally threaded rod 188 moves axially (i.e., parallel to the longitudinal central axis 102) in either the proximal or distal direction when the distal end cap 180 is rotated by the user. As discussed in more detail below, axial movement of the externally threaded rod 188 caused by rotation of the distal end cap 180 is used to introduce a "vertical" bend to the distal portion 132 of the introducer sheath 130.

To ensure that forces are properly transferred to the distal portion 132 of the introducer sheath 130 during operation (e.g., when a user increases or decreases tension in one or more steering cables in the steering cables to introduce a "horizontal" bend and/or a "horizontal" bend to the proximal end of the introducer sheath 130), steerable introducer sheaths according to one embodiment of the present disclosure can further include a torque-driven lock that prevents the introducer sheath 130 from rotating about the longitudinal central axis 102. For example, as best shown in fig. 4A and 4B, certain embodiments may include a torque-transmitting lock 1900 that includes a hollow cylinder having an outer diameter that allows the torque-transmitting lock to pass through the inner bore of the externally threaded rod 188 and an inner diameter sufficient to encompass the radial diameter of the introducer sheath 130, and a recess 1901 at its proximal end, the recess 1901 being engageable with the flange 129. The distal end of the torque transmission lock 1900 includes external threads 1902, the external threads 1902 corresponding to the threads on the internal bore of the transmission lock cap 1903. When threaded onto drive lock 1900, a proximal face of drive lock cap 1903 can be movably engaged with a distal face of distal end cap 180 to secure drive lock 1900 within the bore of externally threaded rod 188 with recess 1901 fully engaged to flange 129. In certain embodiments, the movable engagement between the drive lock cap 1903 and the distal end cap 180 may be facilitated by the use of a thrust bearing 1905, which thrust bearing 1905 may be seated within an indentation 1904 on the distal face of the distal end cap 180. In the final assembly, the introducer sheath 130 passes through the bore of the torque transmission lock 1900 and is immovably attached thereto, and thus the engagement of the recess 1901 with the flange 129 prevents the introducer sheath 130 from rotating about the longitudinal central axis 102 when introducing a "vertical" bend using the distal end cap 180 or when introducing a "horizontal" bend using the steering lever 160.

The proximal terminus of the third steering cable 158 can be attached to the externally threaded rod 188 such that the tension of the third steering cable 158 can be increased or decreased by rotating the distal end cap 180, which causes the externally threaded rod 188 to move distally or proximally along the axis 102. As best shown in fig. 1A and 2D, for example, the distal terminus of the third steering cable 158 is attached at or near the distal tip 136 of the introducer sheath 130 and extends proximally therefrom through the steering lumen 150 until the proximal end terminates in the interior of the handle portion 110 whereupon the third steering cable 158 exits the introducer sheath 130 via an opening 1963 located near the terminal portion of the introducer sheath 130 (i.e., the portion located in the interior of the handle portion 110). In this manner, the distal end of the third steering cable 158 can exit from the steering lumen 150 and become attached to the externally threaded rod 188 by: the third steering cable 158 is attached by passing the third steering cable 158 through an axial bore 1963 in the flange 400 extending from the proximal end of the externally threaded rod 188 and after the third steering cable 158 has exited from the distal end of the axial bore 1963. Likewise, for embodiments of the steerable introducer sheath assembly of the present disclosure that include an introducer sheath similar to the introducer sheath 1300 shown in fig. 3B, the distal end of the third steering cable 1580 exits from the steering cable lumen 1500 and exits the introducer sheath 1300 via substantially the same opening as the opening 1963 shown in fig. 2D and discussed above. Once it has been detached from the introducer sheath 1300, the third steering cable 1580 can be attached to the externally threaded rod 188 by: the third steering cable 1580 is attached by threading the third steering cable 1580 through an axial bore 1963 in the flange 400 extending from the proximal end of the externally threaded rod 188 and after the third steering cable 1580 has exited from the distal end of the axial bore 1963.

As best illustrated in fig. 2A and 2D, when an operator views the sheath assembly 100 from the proximal handle portion 110 and looks distally along the introducer sheath 130, with the introducer sheath 130 extending outwardly in an undeflected position, rotation of the distal end cap 180 in a clockwise direction causes the corresponding threaded rod 188 to move in a proximal direction (i.e., toward the interior of the handle portion 110, as best shown at the top in fig. 2D), which increases the amount of tension placed on the third steering cable 158, resulting in an increase in the "vertical" bending of the distal portion 132 of the introducer sheath 130. Conversely, rotation of the distal end cap 180 in a counterclockwise direction causes the externally threaded rod 188 to move in a distal manner (i.e., away from the interior of the handle portion 110, as best shown in fig. 2D at the bottom), which reduces the amount of tension present in the third steering cable 158 and reduces the amount of such "vertical" bending present in the distal portion 132 of the introducer sheath 130. The "vertical" curvature of the distal portion 132 of the introducer sheath 130 can be seen in fig. 1D (depicting the steerable introducer sheath as viewed from the "right-hand" side), fig. 1D illustrates how the distal portion (136) of the introducer sheath 130 extends in a direction parallel to the longitudinal central axis 102 (fig. 1D, at the center) when the distal cap 180 has been rotated such that the externally threaded rod 188 does not exert tension on the steering cable 158, and how the distal portion (136) of the introducer sheath 130 becomes more "vertical" curved in a direction that is elevated relative to the longitudinal central axis 102 (fig. 1D, at the left) when the distal cap 180 has been rotated to cause the externally threaded rod 188 to move in a proximal manner and increase tension on the steering cable 158. A "self-locking" function that maintains the desired "vertical" bend may be provided by: by configuring the threaded portion of the distal end cap 180 and the externally threaded rod 188 to interact with sufficient friction such that when the user stops rotation of the distal end cap 180, the externally threaded rod 188 remains fixed in its position, maintaining tension in the third steering cable 158 and maintaining the desired "vertical" bending of the distal portion 132 of the introducer sheath 130.

In certain embodiments of the introducer sheath assembly of the present disclosure, the engagement between the end cap 180 and the externally threaded rod 188 can be used to modulate the "vertical" curvature of an introducer sheath similar to the introducer sheath 1300 depicted in fig. 3B. In these embodiments, proximal/distal movement of the externally threaded rod 188 is utilized (directly or indirectly) to selectively increase or decrease the relative tension in the third and

fourth steering cables

1580, 1520, thereby modifying the "vertical" bending of the distal portion 1360 of the introducer sheath 1300 in the direction of the "vertical" axis 103 (i.e., above or below the horizontal plane). This "vertical" bending of the distal portion 136 of the introducer sheath 130 can be seen in fig. 1D (depicting the steerable introducer sheath looking from the "right-hand" side), fig. 1D illustrates how the distal portion (1360) of the introducer sheath 1300 extends in a direction parallel to the longitudinal central axis 102 (fig. 1D, at the center) when the distal cap 180 has been rotated such that the outer threaded rod 188 does not exert tension on the third steering cable 158 and the fourth steering cable 1520, and how the distal portion (1360) of the introducer sheath 1300 lifts more "vertically" in a direction higher relative to the longitudinal central axis 102 (fig. 1D, at the left) when the distal cap 180 has been rotated to cause the outer threaded rod 188 to move by increasing the tension on the third steering cable 1580 and decreasing the tension on the fourth steering cable 1520, and when the distal cap 180 has been rotated to cause the outer threaded rod to decrease the tension on the third steering cable 1580 and decrease the tension on the fourth steering cable 1520 (fig. 1D, at the left), and when moved in a manner that increases the tension on the fourth steering cable 1520, how the distal portion (1360) of the introducer sheath 1300 becomes more "vertically" curved in a direction that is lowered relative to the longitudinal central axis 102 (fig. 1D, at the right).

Certain embodiments of the steerable introducer sheath assembly can include a "horizontal" steering lever (as described above and depicted in fig. 1A-1D and 2A) for modulating the amount of "horizontal" bending present in the distal portion of the introducer sheath and a "vertical" steering lever for modulating the amount of "vertical" bending present in the distal portion 132 of the introducer sheath 130. In such "two-lever" embodiments, the use of a "vertical" steering lever, rather than the distal end cap and externally threaded rod assembly described above for controlling "vertical" bending, provides consistency with respect to the mechanism for altering the bending of the introducer sheath, i.e., the same type of mechanism, the steering lever, is used to modify both "vertical" bending and "horizontal" bending.

For example, as shown in fig. 6A-6D, the distal end cap 180 and its associated components (the external threaded rod 188, the torque driver lock 1900, the driver lock cap 1903, and the thrust bearing washer 1905) from the steerable introducer sheath assembly depicted in fig. 1A-1C and 4A-4B can be replaced with a distal housing assembly 350, as best shown in fig. 6B, the distal housing assembly 350 including

distal housing portions

361 and 362 that together house a vertical steering assembly 351 articulated by a vertical steering lever 360. As best shown in fig. 6B, the vertical steering lever 360 is non-rotatably secured to a first end of the steering column 364 through a hole aligned to receive a retaining pin. The steering column 364 in turn passes through the distal housing part 361 and is non-rotatably fixed at its second end to the main vertical drive gear 365. Main vertical drive gear 365 is positioned within distal housing assembly 350 such that upper vertical drive gear 366 and lower vertical drive gear 369 can be engaged and rotated simultaneously. The upper vertical drive gear 366 is non-rotatably secured to an upper rotatable post 367 that extends inwardly from the housings 374 and 375 (respectively) inside the

distal housing portions

361 and 362, wherein the upper rotatable post 367 is also non-rotatably secured to the upper barrel portion 368. The lower vertical drive gear 369 is non-rotatably secured to a lower rotatable post 370, the lower rotatable post 370 extending inwardly from the housings 376 and 377 (respectively) on the interior of the

distal housing portions

361 and 362, wherein the lower rotatable post 370 is also non-rotatably secured to the lower barrel portion 371.

In certain embodiments of the steerable introducer sheath assemblies of the present disclosure, the vertical steering levers and associated elements described above can be provided in conjunction with an introducer sheath similar to introducer sheath 1300 depicted in fig. 3B. In these embodiments, the third and

fourth steering cables

1580 and 1520 are attached at or near the distal tip 1360 of the introducer sheath 1300, with the cables themselves extending proximally (respectively) through the

lumens

1500 and 1420 until the proximal ends terminate within the interior of the handle inner portion 110, whereupon the proximal ends of the third and

fourth steering cables

1580 and 1520 exit the steering cable lumens 1500 and 1420 (respectively) and exit the introducer sheath 1300 via openings similar to those depicted in fig. 2A (1960 and 1961), and become engaged with one or more steering mechanisms that can selectively increase or decrease the tension in the third and

fourth steering cables

1580 and 1520.

In these embodiments, the proximal end of the third steering cable 1580 is attached to the upper barrel portion 368 and the proximal end of the fourth steering cable 1520 is attached to the lower barrel portion 371. Rotation of the vertical steering lever 360 causes the main vertical drive gear 365 to simultaneously engage and rotate the upper and lower vertical drive gears 366, 369 and their associated upper and

lower barrel portions

368, 371. This in turn causes the third and

fourth steering cables

1580 and 1520 to become coiled around the upper and

lower barrel portions

368 and 371, respectively, such that as the tension in the third steering cable 1580 increases, the tension in the fourth steering cable 1520 decreases, and vice versa. In this way, the third steering cable 1580 and the fourth steering cable 1520 work in unison to increase or decrease the "vertical" bending of the distal portion 1320 of the introducer sheath 1300 in a direction that is raised above or lowered below the horizontal plane.

For example, in certain embodiments, the first and

second steering cables

1580 and 1520 may be affixed to and engaged by their respective upper and

lower barrel portions

368 and 371 in a manner such that rotating the steering lever 360 in a counterclockwise manner (i.e., so that the distal end of the steering lever 360 points in a direction that is raised relative to the longitudinal central axis 102) causes the distal portion (1360) of the introducer sheath 1300 to bend in a raised manner "vertically" relative to the longitudinal central axis 102 (fig. 6D, at the left) as best illustrated in fig. 6D (providing a view of the "two-lever" steerable introducer sheath as viewed from the "right-hand" side), rotating the steering lever 360 in a clockwise manner (i.e., so that the distal end of the steering lever 360 points in a direction that is lowered relative to the longitudinal central axis 102) causes the distal portion (1360) of the introducer sheath 1300 to bend in a raised manner "vertically" relative to the longitudinal central axis 102 (fig. 6D, at the left) The heart axis 102 bends "vertically" in a decreasing manner (fig. 6D, at the bottom), and returning the steering lever 160 to the center position (i.e., so that the distal end of the steering lever 360 points in a direction parallel to the longitudinal center axis 102) causes the distal portion (1360) of the introducer sheath 1300 to extend in a direction parallel to the longitudinal center axis 102 (i.e., without a "horizontal" bend, as in fig. 6D, at the center). In this way, the orientation of the distal end of the steering lever 360 can provide the user with an indication of the presence, directionality, and relative degree of any "horizontal" curvature that has been introduced to the distal portion (1360) of the introducer sheath 1300.

In an alternative embodiment, a third steering cable 1580 and a fourth steering cable 1520 may be affixed to and engaged by

barrel portions

368 and 371, respectively, such that rotating the vertical steering lever 360 in a "clockwise" manner will cause a distal portion (1360) of the introducer sheath 1300 to bend "vertically" above the longitudinal central axis 102, and vice versa.

In certain embodiments of the introducer sheath assembly of the present disclosure, steering levers and elements similar to those described above and certain associated elements may be provided in conjunction with an introducer sheath similar to introducer sheath 130 depicted in fig. 3A. For example, the vertical steering lever may be secured to a first end of a rotatable post that extends through a surface of the distal handle assembly 350 and terminates internally in a manner similar to that shown in fig. 6B with respect to the vertical steering lever 360 and the rotatable post 364. The distal end of the third steering cable 158 from the introducer sheath 130 is affixed (directly or indirectly) to the rotatable post 364 and engaged by the steerable post 364 such that when the steering lever 360 is rotated as described above, the resulting axial rotation of the rotatable post 364 causes the proximal end of the third steering cable 158 to become coiled around or uncoiled from the barrel portion of the rotatable post 364. As the third steering cable 158 becomes more coiled around the barrel portion of the rotatable column 364, the tension exerted on the third steering cable 158 increases, and the amount of "vertical" bending present in the distal portion 132 of the introducer sheath likewise increases. Conversely, as the third steering cable 158 becomes less coiled around the barrel portion of the rotatable post 364, the tension exerted on the third steering cable 158 is reduced and the amount of "vertical" bending present in the distal portion 132 of the introducer sheath 130 is likewise reduced. For example, in certain embodiments, the third steering cable 158 may be affixed to the rotatable post 364 and engaged by the rotatable post 364 in such a manner that rotating the steering lever 360 in a counterclockwise manner (i.e., so that the distal end of the steering lever 360 is raised relative to the longitudinal central axis 102) causes the distal portion (1360) of the introducer sheath 1300 to "bend vertically" above the longitudinal central axis 102 (fig. 6D, at the left), and returning the steering lever 160 to a central position (i.e., so that the distal end of the steering lever 360 points in a direction parallel to the longitudinal central axis 102) causes the distal portion (1360) of the introducer sheath 1300 to return to extend in a direction parallel to the longitudinal central axis 102 (i.e., does not have a "vertical" bend, as in fig. 6D, at the center). Here again, the orientation of the distal end of the steering lever 360 provides an indication of the presence, directionality, and relative extent of any "vertical" bends that have been introduced to the distal portion (1360) of the introducer sheath 1300.

In certain embodiments of steerable introducer sheath assemblies according to the present disclosure, the interaction between a vertical steering lever and an associated steering gear assembly (such as those described above for vertical steering lever 360) can be modified to increase or decrease the "vertical sensitivity" of the vertical steering lever (i.e., the degree to which the "vertical" bend 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 a user to modulate the "vertical sensitivity" by selectively modifying the gear transmission ratio between the drive gear and any associated gear assemblies (e.g., allowing a user to modify the corresponding gear transmission ratio present within the vertical steering assembly 351 shown in fig. 6B). Alternatively, a spring loaded gear column and/or flywheel assembly may be provided for modulating the sensitivity of the vertical steering lever and associated steering assembly.

Embodiments of steerable introducer sheath assemblies that provide a vertical steering lever for controlling "vertical bending" (as detailed above) include a mechanism to lock the steering lever in place once a desired amount of bending of the introducer sheath is achieved. As shown in fig. 6B, for example, the distal handle assembly 350 may be configured with a vertical steering lever 360 that includes a cam surface 385 such that when the steering lever 360 is rotated upward about a steering lever pin that couples it to the steering column 364, the cam surface becomes frictionally engaged with an outer face of an upper portion (361) of the distal handle assembly 350, and the steering column 364 (or associated element) likewise becomes frictionally engaged with an inner face of the upper portion 361 of the distal handle assembly 350. This "locking engagement" is the same as the "locking engagement" depicted in fig. 5A and 5B, which depict the horizontal steering handle 160 in an "unlocked" position (fig. 5A) and in a "locked" position (fig. 5B). In certain embodiments, this "locking" friction may be modulated by providing one or more washers (e.g., wave spring washers (1915) depicted in fig. 5A and 5B) to mediate frictional engagement with the inner and outer faces of the upper portion (361) of the distal handle assembly 350.

Referring again to fig. 6B, embodiments of the steerable introducer sheath assembly providing a vertical steering lever for controlling "vertical" bending may further comprise a vertical steering lever dome 380 located within a vertical dome pocket 381 that is extruded from the outer face of the upper portion (361) of the distal handle assembly 350, thereby modulating the interaction between the cam surface 385 of the vertical steering lever 360 and the outer face of the upper handle portion 361. As best shown in fig. 6B (left inset), the vertical steering lever dome 380 can be shaped to provide a central slot 386 through which the steering lever 360 protrudes, as shown in fig. 6A and 6D, the central slot 386 being of sufficient width to accommodate vertical rotation of the vertical steering lever 360 between the "unlocked" position and the "locked" position, while also providing lateral support for the steering lever 360 when manipulating the steering lever 360 to rotate the steering column 364, and also ensuring that the steering lever 360 is constrained to a direction perpendicular to the axis of the steering lever pin linking it to the steering column 364 when pivoting from the "unlocked" position to the "locked" position (fig. 5B).

Referring again to fig. 6B, providing an embodiment of a steerable introducer sheath assembly for controlling a "vertical" curved vertical steering lever, the vertical dome 380 and vertical dome pocket 381 may be configured to limit the angular displacement of the steering column 364 about its longitudinal axis when the vertical steering lever 360 is manipulated. For example, as best shown in fig. 6B, this may be achieved by flanges (381 and 382) extending from the underside of the vertical dome 380 and may interact with distal faces formed by corresponding protrusions illustrated as 383 and 384 in fig. 6B (left insert) to constrain rotation of the steering lever 360. This protects the third steering cable 1580 and/or the fourth steering cable 1520 from overstraining that may result from a user attempting to over-tighten them using the steering lever 360. In certain embodiments, the

protrusions

383 and 384 and/or the

flanges

381 and 382 can be adjustable such that the degree to which rotation of the steering lever 360 is constrained can be modified according to a user's preference.

As discussed above, the first and

second steering cables

154, 156 work in unison to effect bending of the distal portion 132 of the introducer sheath 130, with the first and

second gear assemblies

168, 174 being engaged simultaneously by the drive gear 166, such that when the operator manipulates the steering lever 160 to increase the tension in the steering cable 154, the tension in the steering cable 156 is reduced by the same amount, and vice versa. The simultaneous operation of the

gear assemblies

168 and 174 prevents slack from accumulating in either of the first and

second steering cables

154 and 156 as the user manipulates the steering lever 160 to effect a "horizontal" bend of the distal portion 132 of the introducer sheath 130. The same is true for the introducer sheath 1300 depicted in fig. 3B, where introducing a "horizontal" bend into the distal portion 1320 of the introducer sheath 1300 by manipulating the steering lever 160 also does not result in slack building up in the first and

second steering cables

1540 and 1560, because as the tension in one of the steering cables increases, the tension in the other steering cable decreases, and vice versa.

However, when the user increases the "vertical" bend of the distal portion 132 of the introducer sheath 130 by increasing the tension of the third steering cable 158, this can in turn cause slack to accumulate in the first steering cable 154 and/or the second steering cable 154. Likewise, when the user modifies the "vertical" bending (in a direction that is raised or lowered relative to the horizontal plane) of the distal portion 1320 of the introducer sheath 1300 by modulating the tension of the third and

fourth steering cables

1580, 1520, this can in turn cause slack to accumulate in the first and/or

second steering cables

1540, 1560. This slack accumulation can cause the operator to experience an undesirable delayed response when attempting to utilize a horizontal steering lever (e.g., steering lever 160 described above) to vary the tension in the first and/or second steering cables 154, 156 (or first and/or second steering cables 1520, 1580) in order to modulate a "horizontal" bending of the distal portion 132 of the introducer sheath 130 (or distal portion 1320 of the introducer sheath 1300). To prevent this, the steerable introducer sheath assembly of the present disclosure can include a mechanism for removing such slack.

For example, as shown in fig. 7A and 7B, the externally threaded rod 188 may feature a proximally extending linkage flange 400 by which axial movement of the externally threaded rod 188 is transferred to a first slack removal assembly comprising a first linkage arm 401, a second linkage arm 402, a flange link post 403 with an associated support cylinder 406, a link arm link post 404 with an associated support cylinder 407, and a link arm retaining post 405 with an associated support cylinder 408. More specifically, as best shown in fig. 7B, the link flange 400 is joined to the distal end of the first link arm 401 through an overlapping opening that receives the flange link post 403; the proximal end of the first link arm 401 is linked to the distal end of the second link arm 402 through an overlapping opening that receives the link arm link post 404; and the proximal end of the second link arm 402 contains an opening through which one end of the link arm retaining post 405 passes and then seats within the link arm retaining post receptacle 410 on the interior of the lower housing portion 114. The first steering cable 154 is threaded through this slack removal assembly, as shown by the dashed lines in FIG. 7B, wherein the

support cylinders

406 and 408 are configured to act as rollers that rotate freely about the

respective posts

403 and 405 to minimize friction with the steering cable 154. As also shown in fig. 7B, the second link cable 156 is threaded through a second slack removal assembly also coupled to the link flange 400, wherein the second slack removal assembly includes a first link arm 411, a second link arm 412, a flange link post 413 with an associated support cylinder 416, a link arm link post 414 with an associated support cylinder 417, and a link arm retaining post 415 with an associated support cylinder 418, and these components are joined together as described above with respect to the first slack removal assembly.

As best shown in fig. 7B, when the externally threaded rod 188 is advanced in the distal direction, the interaction between the link flange 400 and the slack removal assembly causes the

posts

403 and 413 and 415 (and associated

supports

406 and 416 and 418) to become aligned in a more linear manner, which in turn allows the

steering cables

154 and 156 to travel along a shorter path from their distal attachment point within the introducer sheath 130 to their proximal attachment point at the

gear assemblies

168 and 174. Conversely, when the externally threaded rod 188 is advanced in a more proximal direction, the interaction between the link flange 400 and the slack removal assembly causes the

posts

403 and 413 and 415 (and the associated

bearings

406 and 408 and 416 and 418) to become aligned in a larger triangular configuration, with the connecting arm link posts 404 and 414 positioned significantly more toward the exterior of the handle 110 than the flange link posts 403 and 413 and the connecting

arm retaining posts

405 and 415. This triangular configuration removes excess slack from the

steering cables

154 and 156 by causing the

steering cables

154 and 156 to travel along a longer path from their distal attachment point within the introducer sheath 130 to their proximal attachment point at the

gear assemblies

168 and 174. Thus, when the externally threaded rod 188 is advanced in a proximal direction that increases the tension on the third steering cable 158 (which in turn increases the "vertical" bend that can cause the

steering cables

154 and 156 to become slack), the slack removal assembly described above transitions into a triangular configuration that removes excess slack by increasing the distance that the

cables

154 and 156 travel from their proximal gear assemblies to the distal tip of the introducer sheath 130.

Also, for (i) those embodiments that use a "vertical" steering lever 360 in conjunction with the introducer sheath 1300 depicted in FIG. 3B, wherein the vertical steering lever 360 is rotated to modulate the "vertical" bending of the distal portion 1320 of the introducer sheath 1300 (as discussed above and best illustrated in figures 6B and 6D), or for (ii) those embodiments that use a "vertical" steering lever 360 in conjunction with the introducer sheath 130 depicted in fig. 3A, rotating the vertical steering lever 360 to modulate the "vertical" bending of the distal portion 132 of the introducer sheath 130 (as discussed above and best illustrated in fig. 6B and 6C), potential slack introduction into the first and/or second steering cables 1520, 1580 (from the introducer sheath 1300) or the first and/or second steering cables 154, 156 (from the introducer sheath 1300) can be addressed by coupling the rotation of the steering column 364 to a slack removal assembly. For example, one or more coupling rods or cables may be provided to couple the steering column 364 to the slack removal assembly such that when the user rotates the steering column 364 by using the "vertical" steering lever 360 to increase the tension in the third steering cable 158 (thereby increasing the "vertical" bending of the distal portion 132 of the introducer sheath 130), the coupling rods or cables cause the slack removal assembly to become aligned in a "triangular" configuration that functions to remove excess slack from the

steering cables

154 and 156 by causing the

steering cables

154 and 156 to travel along a longer path from their attachment point at the distal tip of the introducer sheath 130 to their proximal attachment point at the

gear assemblies

168 and 174, as discussed above and shown in fig. 7B. Conversely, when the user rotates the steering column 364 by using the "vertical" steering lever 360 to increase the tension in the third steering cable 158 (thereby reducing or eliminating any "vertical" bending of the distal portion 132 of the introducer sheath 130), the coupling rod or cable causes the slack removal assembly to become aligned in a more linear manner, which, as discussed above and shown in fig. 7B, allows the

steering cables

gear assemblies

168 and 174.

Steerable introducer sheath assemblies according to the present disclosure may also include a device locking assembly that allows a user to selectively secure a catheterization instrument within the introducer sheath after the introducer sheath has been advanced (or retracted) to a desired extent and to further exert fine control over the advancement or retraction of a catheterization instrument that has been so attached. Such catheterization instruments may include, for example, a dilator through which a standard length of Baylis RF transseptal device (available from Baylis Medical, Montreal, Canada), a Brockenbrough transseptal needle, or other similar instrument may be introduced. As can be seen in fig. 1A and 8A-8D, for example, such a device locking assembly may be disposed within a proximal aperture 124 (best shown in fig. 8B and 8C) formed when the proximal faces of the upper and

lower housing portions

112, 114 are joined together to form the handle portion 110. As also shown in fig. 8A-8D, the device locking assembly may include a device locking rod (shown as 191a in fig. 8A-8C and 191b in fig. 8D) passing through a proximal face of the handle portion 110, wherein the device locking rod contains a smooth central bore (199) through which instruments for catheter insertion may pass and be inserted into the steerable introducer sheath (130, 1300), and the device locking rod is further configured to variably affix the instruments for catheter insertion in an immovable manner. For example, as best seen from the description of the instrument locking lever 191a shown in fig. 8B and 8C, in certain embodiments, the instrument locking lever may be externally threaded at its proximal side to receive a hemostatic bonnet (196a), through which the catheter-insertion instrument passes (196a) when inserted into the central bore 199 of the instrument locking lever, allowing a user to selectively affix the catheter-insertion instrument in the instrument locking lever 191a in an immovable manner by tightening or loosening the hemostatic bonnet 196 a. Alternatively, as best seen from the description of device locking lever 191b shown in fig. 8D, in certain embodiments, the device locking lever may define a distal collet (collet)194 having a smooth exterior surface, allowing a user to selectively affix the instrument for catheter insertion within device locking lever 191b in an immovable manner by means of a sliding lock knob 196b, which sliding lock knob 196b defines a smooth frustoconical bore 181, which smooth frustoconical bore 181 engages collet 194 and compresses collet 194 inwardly such that it is tightened about the instrument for catheter insertion (which is represented by dilator 159 in fig. 8D).

In certain embodiments, further control over the advancement (or retraction) of an instrument for catheterization (e.g., dilator 159 shown in fig. 8A and 8D) may be provided by: device locking levers (191a, 191b) are mechanically advanced (or retracted) through the proximal face of handle portion 110 by configuring the device locking levers (191a, 191b) to be advanced (or retracted) after the instrument for catheter insertion has been immovably attached as described above. For example, as best illustrated in fig. 8A-8C (showing equipment locking lever 191a) and 8D (showing equipment locking lever 191b), the equipment locking lever may be configured with external threads 1923 that engage corresponding threaded holes (197) through advancement knob (195). The external threads on the device locking stem (191a, 191b), including the external threads that engage the threaded bore 197 and the external threads that engage the hemostatic bonnet 196a at the proximal end of the device locking stem 191a, may be continuous (i.e., "bottom out"), or, as best shown in fig. 8E (depicting device locking stem 191a), include an interrupted "flat" 1925 located along the length of the external threaded region to facilitate use of injection molding manufacturing techniques.

Referring again to fig. 8A-8D, the advancement knob may be rotatably received and retained within the proximal aperture 124 of the handle portion 110 by a retaining flange extending radially from a distal portion of the advancement knob 195 having a larger diameter than the proximal aperture 124. This radially extending retaining flange may be continuous or discontinuous. For example, fig. 8D shows an advancement knob 195 with a continuous retention flange (193 b). Alternatively, fig. 2C shows a proximal view, a side perspective view, and a distal view of the advancement knob 195 with a discontinuous retention flange that includes outwardly depending tabs 1926 that together define a flange having a radius greater than the radius of the proximal aperture 124, thereby ensuring that the advancement knob 195 is axially retained within the handle portion 110 (as best seen in fig. 2D and 9A). As can best be seen in fig. 2C, where the advancement knob (195) has a discontinuous retention flange, it may further include a plurality of vent holes 1927 through the proximal face of the advancement knob 195, said plurality of vent holes 1927 corresponding to the outwardly depending tabs 1926 and being sized and positioned to facilitate manufacturing of the advancement knob using injection molding techniques.

As best shown in fig. 9A, rotation of the advancement knob 195 causes the device locking lever (191a, 191b) to move in a proximal direction (i.e., toward the user, at the left as shown in fig. 9A) or in a distal direction (i.e., away from the user and into the handle portion 110, at the right as shown in fig. 9A). In certain embodiments, device locking levers (191a, 191b) and advancement knob 195 may be threaded such that rotation of advancement knob 195 in a counter-clockwise manner causes device locking levers (191a, 191b) to move in a proximal direction and rotation of advancement knob 195 in a clockwise manner causes device locking levers (191a, 191b) to move in a distal direction; in other embodiments, the threads may be configured such that rotation of the advancement knob in a clockwise manner causes the device locking lever to move in the proximal direction and rotation of the advancement knob in a counterclockwise manner causes the device locking lever to move in the proximal direction. Thus, after engaging the device locking assembly 192 (which would require tightening of the hemostatic bonnet 196a for the device locking lever 191a shown in fig. 9A) to attach the instrumentation for catheter insertion (e.g., the dilator (159) shown in fig. 8A and 8D), the user can exercise precise control over the advancement of the distal tip of the instrumentation for catheter insertion by rotating the advancement knob 195, thereby causing the device locking lever (and the axially attached instrumentation for catheter insertion) to move in a distal manner (extending the instrumentation toward and/or through the distal tip of the introducer sheath) or in a proximal manner (retracting the dilator through and/or away from the distal tip of the introducer sheath). This in turn facilitates performing delicate operations (such as puncturing the interatrial septum) in a very controlled manner.

The steerable introducer sheath assembly can also include an internal guide to prevent the device locking rod from improperly rotating about the axis 102 with the advancement knob 195 when the advancement knob 195 is rotated, which in turn ensures that the device locking rod moves along the axis 102 in the proper distal or proximal manner when the advancement knob 195 is manipulated by the user. As best shown in fig. 9A and 9C, for example, the inner guide 1950 can include a flat cross-shaped distal base having a central bore defined by a hollow cylindrical rod extending in a proximal direction. As best shown in fig. 9B, the cruciform base of inner guide 1950 causes it to seat in a rotationally fixed manner within a guide channel defined by a set of parallel flanges 1927 and a corresponding set of parallel flanges 1928, the set of parallel flanges 1927 extending inwardly from the inner face of the upper handle portion and the corresponding set of parallel flanges 1928 extending inwardly from the inner face of the lower handle portion 114. The proximal end of inner guide 1950 is also configured to engage the device locking lever in a rotationally fixed manner. For example, as best shown in fig. 9C, the engagement between inner guide 1950 and the device locking lever may be mediated by one or more indentations (1930) shown at the distal end of locking lever 191a that engage in a rotationally fixed manner with one or more wing bosses (winging boss)1929 extending proximally from the base of inner guide 1950. In this manner, the internal guide and externally threaded rod are prevented from rotational movement when the advancement knob 195 is turned, and thus the device locking lever is limited to appropriate distal or proximal movement along axis 102.

In certain embodiments, the handle portion 110 can include features that provide visual confirmation as to the integrity of the seal between the hemostatic introducer valve 190 and the dilator 159 (or other catheterized instrument) that has been inserted through the hemostatic introducer valve 190 and into the device lumen 140 of the introducer sheath 130. As best shown in fig. 8A, this may be accomplished by an opening 1931 in the upper housing portion 112, the opening 1931 being positioned to the proximal side of the steering handle 160 and providing a "window" through which the distal side of the hemostatic introducer valve 190 may be viewed. By periodically inspecting the window 1121, a user can readily identify indications (including leakage of air, blood, or other fluid) that the hemostatic seal between the hemostatic introducer valve 190 and the dilator 159 (or other catheterization apparatus) has become compromised, and immediately take action to correct the situation. The window 1931 can also allow a user to visualize the speed at which the dilator is being advanced and the extent to which the dilator has been advanced, and for this purpose, the exterior surface of the dilator (or other instrument for catheterization) can be marked with gradations that can be viewed through the window 1931 to provide an indication to the user of the extent to which the dilator (or other instrument for catheterization) has been advanced into (or retracted through) the introducer sheath.

Certain embodiments of the present invention may include features for improving ultrasound visualization of instruments for catheterization through the introducer sheath 130 during surgery. Under the same imaging conditions, instruments incorporating such features are seen to be quantitatively "brighter" than ultrasound images in a given background medium or tissue, and thus observed during easier use, as compared to instruments not having such features. This makes it easier for the user to visualize the placement and movement of the instrument, which in turn allows the instrument to be used with greater safety and effectiveness, particularly when the instrument for catheterization in question has sharp points or edges or other features that may cause injury during use (as is the case, for example, with the beveled points of dilator 150 shown in fig. 8C and 8D).

In certain embodiments, the features for improving ultrasound visualization may include architectural modifications to the internal and/or external surfaces of instruments for catheterization utilized in conjunction with a steerable introducer sheath assembly according to the present disclosure ("ultrasound visualization modifications"). These ultrasound visualization modifications may include introducing one or more depressions or protrusions into the instrument for catheterization at locations where enhanced visibility is particularly desirable. For example, an ultrasound visualization modification may include one or more punctiform depressions or protrusions that collectively appear as a group of "dots," which may be irregularly dispersed or grouped or arranged in some regular configuration. The ultrasound visualization modification may also include one or more linear grooves or ridges that extend in a perpendicular, parallel, angled, or helical manner relative to the longitudinal central axis of the modified instrument.

In certain embodiments, ultrasound visualization modifications may be introduced only to the interior surface of an instrument for catheterization utilized in conjunction with a steerable introducer sheath assembly in accordance with one embodiment of the present disclosure. Placing the ultrasound visualization modifications on the instrument surface allows keeping the external instrument surface smooth and free of irregularities and thereby helps to prevent damage or undesired alterations to surrounding tissue that may be caused by external irregularities during introduction, manipulation and/or withdrawal of the instrument for catheterization with external ultrasound visualization modifications. Limiting ultrasound visualization modification to the internal instrument surface also prevents such modifications from themselves becoming altered or reduced in efficiency through contact with potentially damaging manifestations, and also prevents structural damage or functional inhibition (including, for example, damage to the introducer sheath and/or the centralized "device" lumen through which instruments for catheter insertion are passed) that may be borne by the steerable introducer sheath assemblies of the present disclosure as a result of contact with the modified external instrument surface.

Ultrasound visualization modifications may include physical or structural modifications to the instrument that result in subjective or objective improvements in ultrasound visibility of the modified instrument as compared to the unmodified instrument. Subjective improvement may include the appearance of a modified instrument using ultrasound visualization being "brighter" or otherwise more distinct when compared to an unmodified instrument visualized under the same conditions. For example, as discussed further below, fig. 10B depicts ultrasound images of the distal tip of a dilator with improved visualization features (bottom left and bottom right images) that appear qualitatively "brighter" relative to the distal tip of a prior art dilator (top left and top right images) viewed under the same conditions in the same background medium, according to embodiments of the present disclosure. In view of this, The qualitative improvement in ultrasound visibility of an instrument having an ultrasound visualization retrofit according to The present disclosure can be confirmed using any known method for obtaining and analyzing subjective observations of individuals who have examined and compared The subjective appearance of a test object using comparable ultrasound techniques and conditions (e.g., MA McCulloch et al, "Limitations of ultrasound visualization Brightness in The Diagnosis of Kawasaki Disease," Journal of The American Society of ultrasound 768-770 (2005)). For example, a series of ultrasound imaging sessions of (i) an instrument with an ultrasound visualization modification in accordance with the present disclosure and (ii) an instrument without such modification inserted into, manipulated within, and withdrawn from a standardized tissue or a test medium may be taken. The video clips of these imaging sessions may then be randomly edited (with any potential identifying information removed or masked) and evaluated independently by a skilled person (e.g., an interventional radiologist, ultrasound technician, cardiologist, or other expert physician with experience using the instrument in question) invited to grade the qualitative "brightness" or "dissimilarity" of each instrument so imaged. Evaluator ratings are collated and processed and statistical methods (such as Cohen's kappa coefficient and Wilcoxon rank sum check) are applied to confirm whether an instrument with ultrasound visualization modifications appears subjectively "brighter" or more distinctive than an instrument without such modifications.

The relative improvement in ultrasound visualization may also be determined by known methods for quantifying and comparing the ultrasound signals returned by the modified and unmodified instruments, including signal processing and measurement techniques designed to extract information from the ultrasound echo signals returned from the control and test items. For example, d.daleki et al recently identified and described some exemplary "high frequency Quantitative Ultrasound techniques, including elastography, which provide metrics for Quantitative assessment of structural, biological, and mechanical properties of Engineered structures" (d.daleki et al, Quantitative Ultrasound for innovative Characterization of Engineered Tissues and Biomaterials, 44 an.biommed.eng' G, 636-648 (2016)). The use of these techniques can be further optimized by implementing computer-aided 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 vs. abnormal based on their identifying characteristics (j.y.wu et al, Quantitative analysis of acquired images for computer-aided diagnosis, 3 j.med.imageng, 014501-1-014501-9 (2016)). To this end, many commercially available software packages may be used with commercial ultrasound systems to identify, isolate, and quantify a wide variety of image characteristics. For example, QLAB Advanced Quantification Software (Advanced Quantification Software) available from Philips Medical System can be used in conjunction with commercial ultrasound systems to facilitate echocardiographic analysis of structure and function (I.S. Salgo, Clinical letters of QLAB Software for Advanced 2D and 3D echo Quantification, Koniklike Philips Electronics N.V. (2006)).

In view of the quantification tools and methods described above (and other quantification tools and methods also known in the art), when (i) an instrument with an ultrasound visualization modification in accordance with the present disclosure and (ii) an instrument without such modification are inserted into, manipulated within, and withdrawn from a standardized tissue or test medium, quantitative improvements in ultrasound visibility of the instrument with the ultrasound visualization modification can be confirmed by first obtaining an ultrasound imaging session of (i) the instrument with the ultrasound visualization modification in accordance with the present disclosure and (ii) the instrument without such modification. For quantitative analysis, video clips of these imaging sessions and the underlying ultrasound information used to form the images are extracted for analysis by a skilled expert or clinician. For example, the analyst may begin by defining a region of interest (ROI) containing a portion of the ultrasound visualization retrofit instrument that has been received, possibly at a defined location within the standardized tissue or test medium or at a predefined time (e.g., one ROI is defined for each of the three stages of the experiment (insertion into, manipulation within the standardized tissue or test medium)). With a defined ROI, an analyst may use a technique called densitometry to isolate ultrasound information that implies an image surrounded by the ROI. The original acoustic information underlying the ROI corresponding to the relevant part of the instrument (i.e. the part where the ultrasound visualization modification is added or not added) has thus been isolated and this original acoustic information can then be processed to provide a quantitative assessment of the structural, biological and mechanical properties of those instruments for catheterization that receive the ultrasound visualization modification and compare them with those instruments for catheterization that do not receive such modification. These tests are collated and processed and statistical methods (such as Cohen's kappa coefficient and Wilcoxon's rank sum check) are applied as necessary to confirm that the instrument with the ultrasound visualization modification is quantitatively "brighter" or more different, or quantitatively improved relative to some other visual characteristic reflected in the isolated ultrasound data, compared to the instrument without the ultrasound visualization modification.

As described above, the ultrasound visualization modification may include one or more punctiform depressions or protrusions that appear generally as a cluster of "dots" or as one or more linear grooves or ridges that extend in a perpendicular, parallel, angled, or helical manner relative to the longitudinal central axis of the modified instrument for catheterization. The linear grooves used to improve ultrasound visualization may be continuous, or consist of smaller segments (which may themselves be joined in a continuous end-to-end fashion, or slightly separated but still form an observable linear groove). For example, fig. 10A depicts a dilator (1920) for catheterization with a steerable introducer sheath assembly of the present disclosure, wherein the dilator has a distal opening of 0.033 inches, wherein the opening increases to a maximum inner bore diameter of at least 0.057 inches as the dilator extends in the distal direction (note that fig. 10A provides a representational depiction of the dilator, not to scale). As shown in fig. 10A, the dilator embodiment (1920) has been modified to improve ultrasound visualization by introducing three longitudinal grooves (1906) into the interior bore surface (1907) near the distal tip (1908), wherein the grooves are disposed 120 degrees apart from each other in a radial fashion about the internal bore (as best shown in fig. 10A, top left inset), and extend parallel to each other in a stepped fashion in the distal to proximal direction, which is also parallel to the longitudinal axis 102 (as best shown in fig. 10A). Each of the three grooves introduced into dilator 1920 has a groove width of 0.012 inches (1909) and a total groove length of 0.375 inches (1109), which total groove length (1910) is further subdivided into six equal steps joined end-to-end with each step having a groove step length of 0.0625 inches (1911), and a groove step depth of 0.003 inches (1912) (as best shown in fig. 10A (inset to the right of body and top)).

Including ultrasound visualization modifications similar to those shown in fig. 10A facilitates visualization of instruments used for catheterization during a procedure performed using ultrasound imaging. This can be seen in fig. 10B, which depicts ultrasound images obtained during introduction (top left) and removal (top right) of a prior art dilator (which does not contain ultrasound visualization modifications), and ultrasound images obtained during introduction (bottom left) and removal (bottom right) of a dilator (1920) illustrated in fig. 10A (which includes ultrasound visualization modifications in the form of the step grooves described above). The appearance of the distal dilator tip indicated by arrows 1912 and 1913 (from the dilator with the "step groove" ultrasound visualization modification depicted in fig. 10A and discussed herein) shows a significant increase in brightness, observable as a series of parallel "stripes" extending downward from the apparent location of the distal tip, as compared to the appearance of the distal dilator tip indicated by

arrows

1910 and 1911 in fig. 10B (from the prior art dilator). This increased brightness in turn facilitates visualization of the distal tip of the dilator during surgery using ultrasound imaging.

In certain embodiments, the dilator 159 can also incorporate a barium impregnated polymer that can enhance the fluoroscopic visibility of the dilator when introduced (e.g., using a steerable introducer sheath assembly according to one embodiment of the present disclosure).

Claims

1. An introducer sheath assembly comprising:

a handle portion including a distal end and a proximal end;

an introducer sheath extending outwardly from the distal end of the handle portion, the introducer sheath including a device lumen configured to slidably receive a corresponding device in an unlocked position;

a device locking assembly disposed at the rear end of the housing portion for locking the corresponding device in the device cavity in a locked position, the device locking assembly comprising:

an equipment locking rod defining an axially extending bore certified to slidably receive the corresponding equipment, the equipment locking rod being axially movable relative to the handle portion;

a clamp disposed on the equipment locking rod, the clamp being selectively positioned in a locked position in which the corresponding equipment is axially fixed relative to the equipment locking rod and an unlocked position in which the corresponding equipment is slidable within the axially extending bore of the equipment locking rod;

wherein the instrument locking assembly further comprises an advancement knob axially fixed and rotatable relative to the handle portion of the body portion, wherein the advancement knob further comprises a threaded bore correspondingly threadedly coupled to an exterior surface of the instrument locking lever, the instrument locking lever threadably coupled to the threaded bore of the advancement knob; and is

Wherein the device locking lever is also engaged with a lever guide disposed within the handle portion to prevent rotation of the locking lever when the knob is rotated.

2. The introducer sheath assembly of claim 1, wherein the rod guide further comprises a guide having a cross-shaped member that causes the guide to be positioned in a rotationally fixed manner within a guide channel defined by parallel flanges extending from at least one interior face of the handle portion.

3. An introducer sheath assembly comprising:

a handle portion including a distal end and a proximal end;

an instrument locking bar defining an axially extending bore certified to slidably receive the corresponding instrument, the instrument locking bar being axially movable relative to the handle portion,

wherein the instrument locking assembly further comprises an advancement knob axially fixed and rotatable relative to the handle portion of the body portion, wherein the advancement knob further comprises a threaded bore correspondingly threadedly coupled to an exterior surface of the instrument locking lever, the instrument locking lever threadably coupled to the threaded bore of the advancement knob; and the external threads on the exterior surface of the equipment locking bar include parallel, interrupted flats.

4. An introducer sheath assembly comprising:

a handle portion including a distal end and a proximal end;

an advancement knob axially fixed and rotatable relative to the handle portion of the body portion, wherein said advancement knob further comprises a threaded bore correspondingly threadedly coupled to an exterior surface of the equipment locking lever, said equipment locking lever threadably coupled to the threaded bore of the advancement knob;

wherein the advancement knob is further characterized by outwardly depending members that collectively define a discontinuous radial flange having a radius that is greater than a radius of a distal aperture in the handle portion, wherein the discontinuous radial flange allows the advancement knob to be rotatably disposed and retained within the distal aperture in the handle portion, and wherein the flanges are mirrored by an opening through the advancement knob.