BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates the components of a percutaneous luminal access system constructed in accordance with the principles of the present invention.
FIGS. 2A-2D illustrate advancement of a pusher tube to deploy a thin-walled, collapsible sheath in accordance with the principles of the present invention.
FIGS. 3A-3C illustrate use of a non-tubular elongate member for advancing and releasing the thin-walled, non-collapsible sheath of the present invention.
FIGS. 4A and 4B illustrate attachment of a hemostasis valve to the sheath of the present invention with subsequent introduction of an access catheter (FIG. 4B).
FIG. 5 illustrates a first method for forming a thin-walled, collapsible sheath in accordance with the principles of the present invention.
FIG. 6 illustrates a second method for fabricating a thin-walled, collapsible sheath in accordance with the principles of the present invention.
FIG. 7 is a detail illustrating a first technique for attaching an elongate member to a distal end of the sheath of the present invention.
FIG. 8 is a second detail illustrating an alternative approach for attaching an elongate member to a distal end of the sheath of the present invention.
FIGS. 9A-9D illustrate cross-sectional views of different combinations of access catheter and sheath, as taken along line 9-9 in FIG. 4B.
FIGS. 10A-10F illustrate introduction of an everting collapsible sheath using a pusher tube over a guidewire into a blood vessel with subsequent introduction of an access catheter and hemostatic valve, in accordance with the principles of the present invention.
FIGS. 11A-11C illustrate introduction of a collapsible sheath into a blood vessel using a non-tubular elongate member in the form of a guidewire.
DETAILED DESCRIPTION OF THE INVENTION
Systems and methods according to the present invention provide minimally invasive and minimally traumatic access to blood vessels and other body lumens. Blood vessels may be arteries or veins, and other body lumens include the peritoneum for peritoneal dialysis, the gastrointestinal tract, and the like. Percutaneous refers to passing a sheath and optionally catheter of the system through the patient's skin into the blood vessel or other body lumen beneath a layer of tissue under the skin.
Systems of the present invention will comprise at least the sheath and an introducer for positioning or advancing the sheath through the skin penetration to the target body lumen. As the sheath will often be left in place for extended periods of time, often days, weeks, or even longer, the sheath will preferably have an anchor or attachment to the skin. The sheath will also usually include a luer or other connector at or near its proximal end to permit attachment to a fluid source, a hemostatic valve (for the introduction of access catheters), or the like.
Once in place, in the absence of internal pressurization, the sheaths will collapse in response to blood or other external luminal pressure so that the sheaths will occupy a minimal space, that is have a very low profile in the body lumen. The ability to collapse and assume such a low profile is particularly advantageous in blood vessels in order to reduce the risk of thrombosis and minimize vessel occlusion.
Optionally, a catheter which is usually but not necessarily non-collapsible, may be introduced through the collapsible sheath, typically through a hemostatic valve attached to the sheath. The catheter will usually have at least one lumen for aspirating and/or introducing a fluid or other material, optionally having two or more lumens. Catheters used for aspiration will be non-collapsible (or have at least one non-collapsible lumen) to withstand a vacuum applied to the lumen. A single catheter may be placed within the sheath for extended periods, and optionally two or more catheters may be placed into the sheath, depending on the relative sizes of the sheath and the catheter. The use of the sheaths in accordance with the principles of the present invention reduces trauma and other risks associated with the exchange of access catheters within the sheath.
Referring now to FIG. 1, an exemplary percutaneous access system 10 comprises a thin-walled, collapsible sheath 12, an introducer 14, a hemostatic connector 16, and an access catheter 18. The sheath 12 includes both a proximal connector 20 and a tissue anchor 22, illustrated as suture wings in FIG. 1. At least a portion of the sheath 12 distal to the anchor 22 will be collapsible and formed from the materials and having the dimensions generally described above. A portion of the sheath 12 proximal to the connector 22, that is between the tissue anchor 22 and the proximal connector 20, may also be collapsible but could also be non-collapsible and need not have the same structure or properties of the distal portions of the sheath 12. It will be appreciated that the proximal portions of the sheath 12 will at all times be maintained externally to the patient and will therefore will not need to be collapsible to provide the benefits intended by the sheath of the present invention.
The introducer 14 may be a tubular or solid-core elongate member, as generally described above, or alternatively can be a tubular pusher for everting delivery of the sheath 12, also as described above. Use of a pusher tube will be described in more detail in connection with FIGS. 2A and 2D and FIGS. 10A-10F. Use of an elongate tube for introducing the sheath will be described in connection with FIGS. 3A-3C and FIGS. 11A-11C.
A hemostatic connector 16 preferably comprises a main branch 24 which connects hemostatic valve 30 to an interior connector 31 received in the proximal connector 20 of the sheath 12. Thus, access catheter 18 or other elongate device may be introduced through the hemostatic valve and coaxially within the lumen of the sheath 12. The hemostatic valve allows the user to form a hemostatic seal over the catheter to prevent or minimize blood loss. The side branch 26 of connector 16 also opens into the interior of the sheath 12 through the proximal connector 20. The opening is generally coaxially over any catheter or other element which is introduced through the hemostatic valve 30 so that a separate annular lumen is formed within the lumen of the sheath 12, as described in more detail below in connection with FIGS. 9A-9D.
The access catheter 18 will typically have at least one central lumen, optionally having two or more lumens running axially from at least one connector 32 to openings at or near the distal end. When there are multiple interior lumens, it will usually be desirable to provide a connector 32 having multiple connections. As illustrated, connector 32 is a conventional luer for connection to a single fluid or aspiration source for introducing or aspirating materials from the blood vessel or other body lumen.
Referring now to FIGS. 2A-2D, introducer 14 in the form of a pusher tube 14A may be used to advance the distal portion of sheath 12 into the target body lumen. Initially, as shown in FIG. 2A, the distal portion of sheath 12 is everted proximally into the interior lumen (not shown) of the pusher tube 14A. An everting fold EF is thus created at the distal end 34 of the combination of pusher tube 14A and sheath 12, as shown in FIG. 2A. As the pusher tube 14A is advanced distally, as shown in FIG. 2B, the everting fold advances distally, thus exposing and elongating the distal portion of the sheath 12, where the advanced distal portion is shown as shown as 12A in FIG. 2B. As the pusher tube 14A continues to be distally advanced, the distal portion of sheath 12, shown as 12B in FIG. 2C, is fully deployed and the distal end of the pusher tube 14A emerges from the open end of the sheath. Usually, the pusher tube will then be removed from the sheath 12, leaving the sheath 12 deployed and having an open internal lumen for receiving an access catheter, fluid to be introduced, or other desired purpose. Optionally, the pusher tube 14A could be left in place to provide an access catheter or other therapeutic or diagnostic catheter. When used as an access catheter, the pusher tube 14A could optionally be provided with a luer or other connector (not shown) at its proximal end.
Referring now to FIGS. 3A-3C, an elongate member 14B may also be used as an introducer for advancing the sheath 12 into a target blood vessel or other body lumen. The elongate member 14B is disposed within the central lumen of collapsible sheath 12 and is frangibly attached to the distal end, typically using an adhesive, heat seal, attachment ring, or other attachment mechanism 40. The elongate member 14B can be detached from the attachment mechanism 40, for example by axially advancing the distal end beyond the attachment member 40, as shown in FIG. 3B. Other detachment mechanisms could also be deployed, as generally described above. The after the sheath has been deployed, the elongate member 14B will usually be removed, leaving the collapsible sheath 12 in place and having an open central lumen for use. Optionally, elongate member 14B could be hollow or otherwise have a lumen, allowing it to be used as an access catheter within the sheath 12, in which case the sheath and elongate member could remain attached and the elongate member in place, as long as the lumen of the sheath is not fully occluded and the profile of the elongate member 14B was acceptable when the sheath was collapsed. The hollow lumen is also useful for delivering the combination of sheath and access member over a guidewire.
Referring now to FIG. 4A and FIG. 4B, regardless of how the sheath 20 is introduced (using either a pusher tube or elongate member), it will frequently be desirable to connect the hemostatic connector 16 to the proximal connector 20 on the sheath 12. The connector 28 may be attached to the connector 20 in a conventional manner. The main branch 24 of the connector allows access catheter 18 to be introduced through the central lumen of sheath 12, as shown in FIG. 4B. The side branch 26 allows materials to be infused through the annular lumen formed about the exterior of the access catheter 18 within the lumen of sheath 12.
Referring now to FIGS. 5 and 6, the collapsible sheaths will typically be formed from a polymeric material, with exemplary polymers having been listed above. A single thin sheet 50 may be rolled and joined along overlapping edges 52 and 54 to form a single axial seam, as shown in FIG. 5. Alternatively, a pair of sheets 60 and 62 may be joined along edges 64A and 64B, and 66A and 66B, to form the desired tubular structure. The sheets will usually not have any pre-defined or pre-set shape so that they may collapse to a generally flat configuration when the exterior pressure exceeds the interior pressure. Conversely, when a fluid or other material is introduced to raise the interior pressure, the sheath structures will expand to a generally circular cross-section. It is possible that two or more tubular sheaths may be axially attached to form a single multi-lumen sheath or sheath assembly. By joining sheaths with different properties, the resulting structure may be asymmetric when filled with infusion fluid. Likewise, joining adjacent edges of two or more films or sheets having dissimilar widths can create a structure that will expand upon pressurization to a non-circular cross-section, particularly if one or more of the sheets or films is stiffer or thicker than the others so that different portions of the sheath have different flexibilities upon expansion.
Referring now to FIGS. 7 and 8, elongate members 14B may be joined at the distal ends of sheaths 12 in a variety of ways. For example, as shown in FIG. 7, the elongate member 14B may have a diameter substantially less than that of the interior diameter of the sheath 12. A distal tip of the member 14B may be attached by adhesives or other means at a single point 70 under the distal tip, allowing the sheath to be folded or otherwise collapse over the member 14B as it is being introduced. Alternatively, the elongate member 14B may have outside diameter which is generally the same as the inside diameter of the sheath 12, allowing an attachment ring 72 to be disposed circumferentially around the distal end of the sheath to provide the desired frangible attachment. The ring 72 may optionally be designed to remain on the distal end of the sheath 12 even after the member 14B is withdrawn. Such a ring structure will hold the distal end of the sheath open even when the sheath is not pressurized when the proximal portions of the sheath will collapse in response to vessel pressure. Such an enlarged distal end of the sheath allows blood flow to continually apply an elongation or tensile force along the length of the sheath to keep the sheath extended, where the enlarged portion acts like a balloon in a flow-directed catheter.
Referring now to 9A, when the access catheter 18 is disposed within a central lumen 13 of the sheath 12, a relatively large annular space 80 remains for introducing fluids. As shown in FIG. 9A, a fluid is being introduced through the space 80, thus inflating the sheath 12. When infusion is stopped, and external luminal pressures are present on the exterior sheath 12, the sheath will generally collapse over the access catheter 18, as shown in FIG. 9B. Usually, the access catheter 18 will have at least a single non-collapsible lumen 82, as shown in FIGS. 9A and 9B, which lumen remains open even when the sheath has collapsed. Alternatively, the access catheter 18 may have two or more lumens 84, as shown in FIG. 9C. Additionally or alternatively, the sheath 12 may have two or more lumens 86, as shown in FIG. 9D. The two or more lumens 86 of the sheath may be independently inflated with different infusion media, or in some cases with the same infusion medium.
Referring now to FIGS. 10A-10F, the thin-walled, collapsible sheath 12 can be introduced using pusher tube 14A over a guidewire GW. Access to blood vessel BV may be established using the modified Seldinger technique, or other conventional method, to place an introducer sheath 12 in place, as shown in FIG. 10A. The guidewire may be advanced to a target site within the blood vessel through the introducer sheath 12. The pusher tube 14 is used to advance the sheath 12 by eversion, until a distal end of the pusher tube 14A emerges from the sheath 12, as shown in FIG. 10C. Usually, the pusher tube 14A is then withdrawn, as shown in FIG. 10D, leaving the slack unsupported sheath 12 in place. The introducer sheath 12 may then be withdrawn, and the tissue anchor attached to the skin S, as shown in FIG. 10E. After attaching hemostatic connector 16, the access catheter 18 may be introduced, as shown in FIG. 10F. The combination of sheath 12 and catheter 18 is now available for both introducing pressurized fluids through the side branch 26 of the connector 16, as well as aspirating or infusing materials through the lumen of the access catheter 18.
The thin-walled, collapsible sheath 12 may also be introduced using an elongate member in the form of a guidewire 14C, as shown in FIGS. 11A-11C. The sheath 12 may be frangibly attached at point 90 to the guidewire-type elongate member 14C, as shown in FIG. 11A. After advancing the member 14C to the desired target region with the blood vessel BV, the guidewire may be detached by axially restraining the sheath 12 and relatively advancing the guidewire member 14C, as shown in FIG. 11B. The sheath 12 is then in place, as shown in FIG. 11C, and ready for attachment and use as shown above in FIGS. 10E and 10F.
It will also be possible to attach the sheath to the outside of an elongate member by tightly wrapping, furling, or otherwise conforming the sheath onto the member. The sheath may be uniformly adhered along the sheath's entire length to the elongate member or alternatively may be adhered only at one or more spaced-apart locations. Biologically compatible adhesives may be used to help furl or roll the sheath onto the elongate member and/or attach a portion of the interior surface of the sheath to the elongate member. In such cases, the sheath may be removed from the elongate member by pressurization, rotation of the elongate member relative to the sheath, solubilization of adhesives (if any), upon exposure to blood or other body fluids, and/or to body temperature, or the like.
While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.
Patent Application
20080033396
