The present invention relates generally to vascular treatment procedures, and in particular to devices for providing vascular access and directional control of a guidewire.
Endovascular procedures involve surgical access to venous or arterial blood vessels. These procedures can be surgical (e.g., relief of occlusion), therapeutic (e.g., involving the intravascular administration of fluids or medications such as analgesics), or diagnostic (e.g., monitoring of intravascular parameters such as arterial or venous pressure).
An endovascular procedure entails obtaining access into the vasculature and maintaining it for the duration of the procedure. This is most commonly done by placing an “introducer” endovascular sheath in the blood vessel to enable passage of the interventional instruments in and out without losing the entry point or causing damage to the vessel. Placement of an endovascular sheath may be performed using the modified Seldinger technique. This involves puncture of the vessel with a needle, passage of a guidewire through the needle, removal of the needle, incision of the skin, placement of a catheter sheath over the guide-wire, and ultimately, removal of the guide-wire and any interventional instruments that were introduced.
A “retrograde” puncture is against the direction of blood flow from the heart, and “antegrade” puncture is in line with the direction of blood flow. For example, a commonly accessed vessel is the common femoral artery (CFA). If the access sheath is directed toward the aorta and away from the leg, it is termed retrograde access. Conversely if the sheath is directed toward the patient's foot, and in the direction of blood flow, it is termed antegrade.
Some procedures involve access to more than one vessel. For example, the CFA bifurcates into the profunda femoris (PF) and the right superficial femoral artery (SFA), and it may be necessary to access both vessels. Due to anatomical constraints, accessing either the PF or the SFA generally occurs through a puncture in the CFA, which can be reached through the skin; the guidewire is then sent into the vessel of interest. Because of the bifurcation, however, it can be difficult to ensure entry of a guidewire into the correct vessel. Suppose, for example, a patient has a blockage 102 in his SFA as shown in
When the anatomy of branch vessels becomes tortuous and serpentine, advancement of wires and devices can be even more challenging, as the shape of the vessels can cause retraction and telescoping of the guidewire in the opposite direction. The aortic arch—the portion of the main artery that bends between the ascending and descending aorta—is representative of such vessels and must be traversed in carotid stenting procedures. Indeed, most technical failures in carotid stenting are related to a complex aortic arch, and this has led to a classification system (aortic arch elongation classification) reflecting various levels of procedural difficulty in vessel cannulation. This is illustrated in
Accordingly, there is a need for improved means facilitating access to vasculature, particularly tortuous and serpentine vessels.
Various embodiments of an endovascular sheath in accordance herewith include a shaft portion with primary and secondary lumens, and an exit opening. The sheath may be introduced into a blood vessel along a guidewire that has already been placed within the vessel (typically via a Seldinger needle technique). Along the shaft is an opening that permits exit of a second guidewire introduced into the primary sheath lumen. A third guidewire is passed through the secondary lumen to stiffen the device. The sheath may include, within the primary lumen, one or more features that encourage exit of the second guidewire through the opening at an optimal angle. For example, the primary lumen may include a ramp or other internal feature angled to direct exit of the second guidewire at approximately the appropriate angle to pass into an adjoining vessel. Following advancement of the second guidewire, a second sheath or catheter may be passed therealong through the device, also exiting via the opening. This second sheath branches off, e.g., into another vessel that would be difficult to access with a single sheath due to the tortuous path involved.
Accordingly, the implementations described herein may provide reliable placement of multiple intravascular guidewires and sheaths/catheters notwithstanding extreme vessel anatomies. The device may be used at branch vessel bifurcations or for directional control within the main trunk of a blood vessel prior to a bifurcation, e.g., to re-direct and change the course of the wire up to 180°. This permits the guide wire to be placed in a 180° orientation to the original placement of the sheath, and if the sheath is removed, the guidewire will now permit introduction of a second sheath along the newly established course change. Thus if the original sheath and guidewire is oriented in an antegrade position, then using this technique, the second sheath can be re-directed in a retrograde fashion using the original access point without an additional puncture/access of the vessel.
Therefore, in a first aspect, the invention pertains to an endovascular introducer sheath. In various embodiments, the introducer sheath comprises an elongated body comprising a head portion and, extending therefrom, a shaft portion including primary and secondary lumens, wherein (i) the primary lumen terminates in an open distal end, (ii) the primary lumen is sized to accommodate a plurality of guidewires, and (iii) the secondary lumen extends parallel to but is physically isolated from the primary lumen and is sized to receive a stiffening wire; an opening through the shaft portion to the primary lumen but not the secondary lumen, the opening being spaced apart from the distal end; and means for directing a guidewire received at the head portion out the opening at an exit angle.
In some embodiments, the exit angle is no greater than 90° relative to the shaft portion. The directing means may be a ramp within the interior lumen; the ramp may descend into the primary lumen from a distal peripheral edge of the opening. In some embodiments, the ramp has a scooped profile and extends into the lumen sufficiently to cause contact between a lower edge of the ramp and a guidewire positioned against the interior lumen opposite the opening.
The introducer sheath may include an inflatable member within the primary lumen and an inflation channel fluidically coupled to the inflatable member, where at least a portion of the inflatable member is opposed to the opening. In some embodiments, a portion of the inflatable member may be directly opposed to the opening. The inflatable member may reside on an exterior surface of the shaft and substantially surrounding but not occluding the opening, e.g., having the form of a cuff.
The opening is generally sufficiently large to allow therethrough a sheath advanced along the second guidewire. In some embodiments, the distal end has a pigtail configuration.
In another aspect, the invention relates to a method of accessing a branched blood vessel along a tortuous endovascular path comprising an arch and a target vessel branching therefrom. In various embodiments, the method comprises the steps of introducing a first sheath into the arch by inserting it into a remote extracorporeal site and guiding the sheath over a first guidewire, where the first sheath comprises (a) an elongated body comprising a head portion and, extending therefrom, a shaft portion including primary and secondary lumens, wherein (i) the primary lumen terminates in an open distal end, (ii) the primary lumen is sized to accommodate a plurality of guidewires, and (iii) the secondary lumen extends parallel to but is physically isolated from the primary lumen; and (b) an opening through the shaft portion to the primary lumen but not the secondary lumen, the opening being spaced apart from the distal end; positioning the opening opposite the target vessel; directing a second guidewire received at the head portion out the opening at an exit angle, the exit angle conforming to an angle of the target vessel relative to the shaft portion; and directing a second sheath into the target vessel along the second guidewire.
The method may further comprise the step of stabilizing the second sheath following introduction thereof into the target vessel using an inflatable member. For example, the inflatable member may disposed within the primary lumen with at least a portion of the inflatable member being opposed to the opening; or the inflatable member may be disposed on an exterior surface of the shaft, substantially surrounding but not occluding the opening. In the latter case, the inflatable member may have the form of a cuff surrounding the opening.
In some embodiments, the method further comprises the step of advancing a stiffening wire through the first sheath before advancing the second sheath therethrough. The first and second guidewires and the stiffening wire may be left in place following placement of the second sheath in the target vessel.
Reference throughout this specification to “one example,” “an example,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the present technology. Thus, the occurrences of the phrases “in one example,” “in an example,” “one embodiment,” or “an embodiment” in various places throughout this specification are not necessarily all referring to the same example. Furthermore, the particular features, structures, routines, steps, or characteristics may be combined in any suitable manner in one or more examples of the technology. The headings provided herein are for convenience only and are not intended to limit or interpret the scope or meaning of the claimed technology.
In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, with an emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the present invention are described with reference to the following drawings, in which:
Refer first to
The sheath 200 may be made from metal or any suitable polymeric material such as plastic (e.g., PTFE, FEP, PFA, PE, one or more polyamides, one or more polyimides, a thermoplastic elastomer such as PEBAX, or one or more urethane polymers), and may be provided with a hydrophilc coating to minimize vessel trauma.
During a procedure, a guidewire is first inserted via a needle into the blood vessel 240 to which access is desired. A wire is advanced through the needle and then, maintaining the wire, the needle is removed. The sheath 200 is introduced through the skin and into the vessel 240 along the guidewire. If used, the dilator 220 is first inserted through the head portion 215 of the sheath 200 and the tapered distal end thereof (not shown) emerges from the distal end of the sheath 200. The tapered dilator eases the passage of the sheath 200 into the vessel 240 and is removed following placement.
With reference to
As illustrated in
Alternatively, the lumen 515 may be sized to accommodate a dilator (which rides along the first guidewire during insertion) as well as a second guidewire, which once again emerges from the window 230 as described above. Once the sheath 200 has been introduced and the second guidewire advanced into the bifurcated vessel, the dilator is removed.
In an alternative approach, the interior or exterior surface of the sheath 200 may be tapered, and it is the taper (more specifically, the effect of the taper on the diameter of the interior lumen) that forces the second guidewire out the window 230, which, once again, may be beveled to enforce a desired exit angle. One example of this approach is illustrated in
As noted, the exit angle depends on, and may be close or equal to, the angle of bifurcation between the two vessels with which the device is to be used. In general, the exit angle—that is, the angle between the guidewire as it emerges from the window and the exterior surface of the sheath—is less than 90°, and it most cases less than 45°. For example, the branching angle between the profunda and the SFA may range, for example, from 30° to 35°.
During some procedures, the sheath as described herein may be removed following placement of the second guidewire and, in some cases, replaced with a conventional catheter sheath before, for example, a cutting operation is performed. To ease removal of the sheath with the second guidewire in place, a groove or slit may be included in the shaft portion. Such a slit is illustrated in
When the sheath 700 is retracted from a blood vessel, the slit 735 allows the second guidewire to enter the lumen of the sheath 700, thereby avoiding harm to the interior wall of the blood vessel that could occur if, for example, the guidewire were to be forced against the blood-vessel wall by the exterior surface of the sheath 700. A similar protective function can be achieved using a groove or elongated depression in the surface of the shaft portion 710, between window 730 and the terminus of the sheath 700, rather than a slit penetrating all the way through the shaft wall. Indeed, it may not be possible to employ a slit along the full window-to-terminus distance depending on the means used to direct the second guidewire out the window 730. As shown in
An advantage of the invention is its ability to provide support and stability in a complex vascular environment. When a sheath in accordance with the invention is placed into the PF or another vessel, contact between the skin and the end of the sheath helps secure and reinforce the shaft portion. When an instrument such as a wire or catheter is then advanced through the mid-shaft opening, it is mechanically supported by the sheath. In conventional procedures, the force applied to a wire or catheter and transferred by contact to a calcified occlusion without support often results in buckling and redirection of the instrument (e.g., into a branching vessel such as the PF). The support and stability provided by a sheath in accordance herewith, by contrast, helps prevent the unwanted redirection of the wire and thereby sustains application of force at the target.
When the anatomy of branch vessels becomes tortuous and serpentine, advancement of wires and devices can cause retraction and telescoping in the opposite direction. As illustrated in
Depending on the anatomy and the nature of the arch elongation, the type of arch and branch variants, it may be desirable to stiffen the sheath 900 as illustrated in
The lumen 940 is physically isolated from (i.e., does not communicate with) the primary lumen 945.
In various embodiments, an inflatable balloon is positioned within or outside the first sheath 900 to retain the second sheath 930 in place when deployed through the window 920 and into the target branch vessel. This precludes movement or retraction of the second sheath 930 following placement. One balloon configuration is shown in
The balloon 1210 extends along the air channel 960 described above, which terminates and opens into the balloon 1210. The other end of the air channel 960, at the proximal end of the primary sheath 900, is connected to an inflation device, such as a squeeze bulb, syringe or pump operated by the clinician. Some inflation devices provide controlled measures of pressure based on atmospheric pressure. Suitable inflation devices include the basixTAU device marketed by Merit Medical, South Jordan, Utah. In its uninflated state, the balloon 1210 occupies little volume within the lumen of the primary sheath 900 and does not interfere with travel of the secondary sheath 930 through the primary sheath 900 and out the window 920; when inflated, as illustrated in
It should be noted that depending on the configuration and procedure for which the device is employed, the ramp structure 510 may itself impart sufficient support to the exiting second sheath 930 to prevent movement or retraction without the need for a balloon.
The overall operation of the device in a representative procedure is shown in
Thus, in various embodiments, support within complex branch vessels is provided by the primary sheath (which may, for example, anchor in the aorta); the window or opening aligned with the target branch vessel, and the secondary sheath when advanced into the target vessel and immobilized using the inflatable member. Up to three guidewires can be used simultaneously: the stiff wire over which the primary sheath is initially advanced, and which may remain in place; the stiffening wire advanced through the secondary lumen; and the third guidewire over which the secondary sheath is advanced through the mid-shaft opening.
It is to be understood that the features of the various embodiments described herein are not necessarily mutually exclusive and can exist in various combinations and permutations, even if such combinations or permutations are not made express herein, without departing from the spirit and scope of the invention. In fact, variations, modifications, and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention.
This is a continuation-in-part of U.S. Ser. No. 16/209,133, filed on Dec. 4, 2018, the entire disclosure of which is hereby incorporated by reference.
Number | Date | Country | |
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Parent | 16209133 | Dec 2018 | US |
Child | 16250030 | US |