WO2011069505A1

WO2011069505A1 - Intravascular device with radially expandable section

Info

Publication number: WO2011069505A1
Application number: PCT/DK2010/000167
Authority: WO
Inventors: Hans Jørgen PEDERSEN
Original assignee: Fowsion Aps
Priority date: 2009-12-09
Filing date: 2010-12-07
Publication date: 2011-06-16

Abstract

The present invention relates to a device to be inserted into a cavity, a hollow organ or the like of an living being such as a human being or more generally in an animal, where the device comprises a functional part that is preferably not to get in contact with the internal walls of the cavity or hollow organ. The device comprises a part having a radially expanding section to surround the functional part and possibly to contact the walls forming some fixation of the device inside the cavity or the hollow organ. The expandable section in the preferred embodiment is formed by a shape memory material, a spring material etc.

Description

Intravascular device with radially expandable section

Background of the invention It is a well known fact that the concentration of, for example, an analyte in the intravascular tissue is different from that in the vasculature media, such as the moving blood stream. For systems comprising a functional part operating for example in dependence of a concentration within the vasculature media, it is desirable for it to be kept free from vascular walls and thereby the intravascular tissue.

A number of documents relates to methods and devices solving similar problems, such as US 5,769,821 , disclosing a catheter tip retainer for retaining a catheter tip in a fixed position within a blood flow and preventing it from contacting a blood vessel wall. The apparatus includes a tip retainer at the distal end of the catheter that stabilizes the tip of the catheter relative to the blood vessel. The catheter tip is retained within the blood vessel spaced from the wall to ensure that it does not contact the wall of the blood vessel. This reduces damage to the blood vessel caused by chronic movement and contact between the catheter tip and the wall of the blood vessel. In one embodiment, the tip retainer includes a prong that penetrates the wall of the blood vessel, thus preventing the catheter tip from moving longitudinally within the blood vessel. In alternative embodiments, the tip retainer contacts the wall but does not penetrate it.

Different embodiments are disclosed in the document, where in one of the embodiments, the tip retainer is two or more loops of wire that flex outward and contact the wall. In a further embodiment the tip retainer includes fletchings to anchor the catheter tip in the blood vessel. Alternatively, the tip retainer is a plurality of single straight wires that are prestressed to flex outward or straight wires with loops on the end.

In one embodiment disclosed, a plurality of members run from the proximal end of the catheter to the distal end where they extend radially outward until they contact the wall of the blood vessel. In this embodiment, the catheter includes withdrawal means for withdrawing the positioning means into the catheter such that the positioning means is prevented from damaging the wall of the blood vessel when the catheter is withdrawn from the blood vessel. The withdrawal means includes guideways running from the proximal end of the catheter to the distal end of the catheter. The positioning means extends from the proximal end to the distal end of the catheter within the guideway.

Another document, US 5,256,146, discloses an anchoring wire element formed in a configuration such that it radially expands to mechanically engage the side walls of a blood vessel. In the configuration shown in FIGS. 2 through 4, the anchoring wire is formed in a multi-turn helical or "pigtail" configuration such that it is in continuous contact with the vessel side walls and defines a clear flow area through the centre of the vessel for blood flow. Such a shape can easily be generated by wrapping guide wire stock around a cylindrical mandrel along a helical path. In its free condition, anchoring wire defines a diameter slightly larger than the inside diameter of the blood vessel, such that when deployed in the blood vessel, an expansion force is exerted against the blood vessel wall for anchoring purposes. One end of the anchoring wire is received within the infusion catheter lumen and is bonded thereto so that these elements remain connected. The system comprises an introducer catheter with a lumen being sufficiently large to enable the infusion catheter and the anchoring wire to be inserted through it. Due to the stiffness of the introducer catheter, as the anchoring wire is pulled to retract within the lumen, it assumes a nearly straightened or

"streamlined" configuration, as compared with the expanded state as shown in Fig. 2. This condition of Fig. 1 exists during insertion or withdrawal of the system. The document US 5,122,125 discloses a guiding catheter, substantially consisting of a hollow tube (lumen) of flexible torsion-stiff material, onto an end of which connects a tubular extension of flexible material, which is curved according to predetermined varying radii of curvature, and the free end portion of which is provided with a softer material than the flexible material, wherein the end portion of softer material is provided with at least three radially protruding elements, preferably having an arc-like outer curvature seen in the tangential direction.

Balloon catheters are also well described in the art, such as for example EP 0 750 919 disclosing an intravascular dwelling balloon catheter for arterial perfusion, having a basic body formed as a whole into a flexible form, having a prespecified length, and made of a material such as polyvinylchloride resin, polyurethane resin, or silicon rubber. Formed in a tip section of the basic body of the catheter is a small diameter section, and a balloon made of silicon rubber is attached to the small diameter section. The balloon closely embraces the small diameter section before it is expanded, and the diameter when so embracing the small diameter section is substantially the same as that of the body section other than the small diameter section. The system comprises ribs provided on an external surface of the balloon. In one disclosed example the ribs are formed by providing projecting strips or the like crossing each other as shown in Figs. 4 and 5. Such ribs are provided in a mesh-like form over the entire surface of the balloon, but so that none of the ribs crosses the centre line E of the basic body of the catheter. The ribs may comprise a first portion in which a plurality of ribs is provided at a predetermined spacing from each other and each inclined at a predetermined first acute angle in the distal direction relative to the centre line E of the basic body of the catheter, and a second section in which a plurality of ribs is provided at a predetermined spacing from each other and each inclined at an obtuse second angle in the direction opposite to the distal direction relative to the centre line E.

The present invention, in the same manner as disclosed in some of the above cited documents, relates to a device to be inserted into a cavity, a hollow organ or the like of an animal body, where the device comprises a functional part that is preferably not to get in contact with the internal walls of the cavity or hollow organ. A number of such systems exist having such functional parts, such as in general chemical or biochemical probes, optic probes where the device could comprise fibre optics, electrochemical probes etc.

The object of the present invention especially relates to such a device being formed in a simple manner to reduce manufacturing costs, but also to a device formed in a manner to minimize the risk of small parts of the device breaking off with the risk to make damage within the living creature (such as a human being or more generally an animal). Another advantage is to shield the functional part, such as a micro-dialysis membrane, from being damaged during introduction and operation, to affect its functionality.

Summary of the system

The object is obtained by introducing a device to be used in combination with an introducer, where the device comprises an outer member and an inner member, the inner member being positioned in the inner lumen of the outer member, and wherein the device distally further comprises an expandable section able to expand in the radial direction. This radially expandable section helps keeping a certain distance from a section of the inner member being in the inner volume of the expandable section to the walls of, for example, a body cavity or a hollow organ, such as the intravascular walls. The expandable section may further help fixing the device.

Preferably, the inner and outer members are tubular shaped, but are not limited to any particular shape, the important thing being the functionality of the members, where especially the outer member needs an inner hollow that is able to contain at least a part of the inner member.

In the same manner the introducer in the preferred embodiment is tubular shaped, but may have any shape being able to contact the outer member, or at least the necessary sections of the outer member, through a skin. Preferably, the expandable section is formed by a plurality of rib elements having their proximal ends fixed to the distal end of the main outer tube and being mutually connected at their distal ends. In a further preferred embodiment of the present invention, the outer member and the rib elements are formed in a single body. Hereby the number of construction parts of the device is reduced to give an easier manufacturing process, but also to minimize the risk of parts breaking off when the device is inserted with the risk to make damage within the living creature (such as a human being or more generally an animal).. Another advantage is to shield the functional part, such as a micro-dialysis membrane, from being damaged during introduction and operation, to affects its

functionality.

In this embodiment the distal ends of the rib elements form an outer distal tube that has a distal opening being plugged in any manner known in the art, to ensure that the edges of the tube do no harm to the walls, such as the intravascular walls.

In the preferred embodiment of the present invention, the expandable section in its expanded state has a diameter being substantially larger than the diameter of the outer member, and the inner diameter of the introducer tubular part is larger than the outer diameter of the outer member, but the expanded diameter of the expandable section is larger than the outer diameter of the introducer tubular part. This means that the expandable section will be in a compressed or collapsed state when resting inside the introducer during insertion or extraction of the device to or from the body, but in an expanded state when being outside the introducer.

In further a preferred embodiment, at least the rib elements are made of a shape memory material, but more preferred the whole of the outer member and the expandable section and optionally also the outer distal tube are formed by a shape memory material. The material of the expandable section is then processed so that it will seek towards a radially expanded state when in a relaxed state. Alternatively the material may be made of a normal spring material, or of any other material and / or in any construction, as known in the art to ensure that such an expandable section will expand to an expanded state when unaffected by compressible forces, such as being inside a tube of a radial diameter less than the radial diameter of the expandable section in its expanded state.

One preferred material is Nitonol or any material used especially to form stents as it is well known in the art, but the material choice is not limited to such.

In further a preferred embodiment of the present invention, the proximal end of the introducer provided to be external to the skin is equipped with a second connector and the proximal end of outer member is fixed to a first connector, the first and second connectors being adapted to be fixed to one another, and the length of the outer member being such, that when the first and second connecters are fixed to one another, then the expandable section extends out of the distal opening of the introducer. In this manner it is ensured that the device is fixed to the introducer in a manner that permits the expandable section to project from the introducer during operation of the device, even though the system is constructed in a very simple manner. In a further preferred embodiment of the present invention, the inner member comprises a functional section, the functional section being positioned within the expandable section during operation of the system.

In one preferred embodiment of the present invention, the inner member comprises at least one fluid conduit for delivering substances like drugs to the tissue. In one preferred embodiment, the functional section is a semi-permeable section, and the inner member may comprise at least two fluid conduits, the functional section being a micro-dialysis probe as well known in the art, a perfusion fluid being transferred to the functional section through a first of the fluid conduits of the inner member, and away from the functional section through a second fluid conduit, enriched with analytes being 'collected' by the perfusion fluid as they diffuse across the semi-permeable section (optionally a semi-permeable membrane).

To ensure a sufficient stability, stiffness, ruggedness etc. of the expandable section, the rib elements may be formed as structured elements. In one such embodiment the rib elements comprise at least first sections running at a first angle and second sections running at a second angle relative to an axis parallel to the length direction of the extension of the expandable section, where the first and second sections may be curved.

In another such embodiment, the rib elements form a bifurcated and/or branched structure or network of rib elements with at least first sections running at a first angle and with sections running at a second angle relative to an axis parallel to the length direction of the extension of the expandable section.

The functional section, e.g. a semi-permeable section, may comprise

supperters, such as for example metal threads of Nitenol or other materials comprising a substantial stiffness, and adapted to reduce bending of the functional section. This especially would be an advantage where the materials of the functional section would sustain only little bending.

Figures

Fig. 1 shows the main problem to be solved by the present invention.

Fig. 2 shows an example of how to solve the main problem of the present invention.

Figs. 3A-D illustrate manufacturing methods of the outer member and rib elements of the present invention.

Fig. 3D shows a simplified front view of one embodiment of the outer tube.

Figs. 4A-C illustrate the present invention during insertion, during operation and during removal.

Fig. 5A and 5B illustrate alternative designs of the constructions of the rib elements.

Figs. 6A-C illustrate the outer member and the introducer equipped with connectors, and how the functional section of the inner member is positioned within the expandable section.

Detailed description of the invention

Fig. 1 is a simple illustration of a configuration where a device (1) is introduced into a vasculature (2) of a person through an introducer (or catheter) (4). The illustrated device comprises a sensor section (3). It shall be noted that the present invention is not limited to devices comprising a sensor section (3) or even performing any sensing or analysing operation, or introduced into a vasculature. It applies to any system where a device (1) is to be introduced into a cavity or hollow organ of the body through an introducer, and where it is desirable ensuring that at least a part of the distal end of the device (1), or the functional part, is not in contact with the internal walls of the cavity or hollow organ.

In the described but non-limiting example of the present invention, the system comprising the device (1) and the sensor section (3) is a micro-dialysis probe as they are well known in the art, where the device (1) comprises a tubular system for transferring a perfusion fluid to the sensor section (3) being a section permeable to the species of interest, the analyte, in the surrounding media.

Here the perfusion 'collects' the analyte as it diffuses across the permeable section. This enriched perfusion fluid would then comprise the analyte in a concentration that may be translated to the concentration in the surrounding media, and is then removed again from the sensor section (3) through the tubular section for further analysis.

A number of other analysis systems exist to which the invention would also apply, such as in general chemical or biochemical probes, optic probes where the device (1) could comprise fibre optics, electrochemical probes etc.

It is a known problem for such systems that the concentration of the analyte in the intravascular tissue may differ from the concentration of the analyte in the vasculature media, such as the moving blood stream. It is therefore preferred that the sensor section does not touch the vascular walls and thereby the intravascular tissue, since this would cause misleading concentration

measurements.

It is therefore desirable to ensure a distance from the vascular walls to the sensor section (3) ensuring that it is only surrounded by the intravascular media. Fig. 2 illustrates the basics of the present invention, where the device (1) with the sensor section (3) is introduced through the introducer (4) in one preferred embodiment used in the following as the example, comprising an introducer tubular part (5). The device (1) comprises the inner member (6) (the tubular system for communicating the perfusion fluid, optic fibres, electrical wires etc.) comprising the sensor section (3).

The device (1) further comprises an outer member (7) where the inner member (6) extends within the outer member (7). The device (1) distally further comprises an expandable section (8) able to expand in the radial direction.

When the device (1) is fully inserted intravascularly for operation of the device the expandable section (8) ensures that the sensor section (3) is unable to contact the vascular walls and thereby get in contact with the intravascular tissue. In one preferred but non-limiting example the sensor section (3) is situated within the inner volume of the expandable section (8) during operation.

In one preferred embodiment of the present invention, the expandable section (8) is formed by a plural of rib elements (10) having their proximal ends fixed

(11) to the distal end of the outer member (7) and connected to one another at their distal ends (12).

In another preferred embodiment of the present invention, the expandable section (8) is formed as an integral part of the outer member (7). In one preferred version of this embodiment, the expandable section (8) is formed by rib elements (10) being formed from the same single body as the outer member (7), as seen in Fig. 3C. The ribs (10) are then advantageously formed by 'cutting' them in the single body in any known manner, such as by laser, electro polishing, ceramic or sand blasting, etc. This is illustrated in Figs. 3A, 3B and 3C, where a tube of some material (13) is provided and a number of 'cuts' (14a) around the circumference are made running in the longitudinal direction of the tube (13), Fig. 3A, or with an angle relative to an axis (19) parallel to the longitudinal direction. Alternatively whole areas are cut (14b) away, Fig. 3B. When these 'cuts' (14) are Opened' (15), as seen in Fig. 3C, then the ribs (10) are formed. In this embodiment the ribs (10) are connected at their distal ends

(12) in the shape of a tube, the distal outer member (16). The 'cuts' (14, 14a, 14b) could optionally be curved. Fig. 3C also illustrates a further embodiment of the present invention, where a plug (20) is introduced to the distal outer member (16) ensuring a substantially 'smooth' surface of the distal end of the device (1) to ensure it does no damage to the internals of the vasculature, cavity, hollow organ etc. The plug may be inserted and fixed to and / or in the distal outer member (16) in any manner as known in the art.

Alternatively, or additionally, to introducing the plug (20), the end tip of the distal outer member (16) may be shaped, or reshaped, to a more 'rounded' shape (23) as illustrated in Fig. 3D, and optionally to close the opening of the distal outer member (16) altogether. This reshaping may be done in any manner as known in the art, by heating and subsequently reshaping it, by pure mechanical reshaping etc., but could also simply be the form of the pre-tube (13) as it is constructed.

Fig. 3D shows a view seen into the proximal end of the outer member (7) showing an embodiment with four ribs (10) extending in the radial direction. In one preferred embodiment the single body is made of a shape-memory material of any kind as known in the art, but is preferably made of a shape- memory material being biocompatible. Alternatively to being biocompatible the shape-memory material is covered by a biocompatible coating of any kind known in the art. Alternatively the single body could be made of a spring material (steel, stainless steel etc.), or of any other material and / or in any construction, as known in the art to ensure that such an expandable section will expand to an expanded state when unaffected by compressible forces, such as being inside a tube of a radial diameter less than the radial diameter of the expandable section in its expanded state.

This 'single body' embodiment is especially preferred in that it reduces the number of components forming the part of the device (1) to be introduced intravascularly, thereby easing the manufacturing process, but also minimizing the risk of small parts of the device (1) breaking off within the vascular system with the risk to make damage within the living creature (such as a human being or more generally an animal).. Another advantage is to shield the functional part, such as a micro-dialysis membrane, from being damaged during introduction and operation, to affect its functionality.

In the same manner as the expandable section (8) may expand from a collapsed state, it is able to collapse from the expanded state. Fig. 4A-C illustrates the insertion procedure and functionality of the present invention. The internal diameter of the introducer (4) is larger than the outer diameter of the outer member (7) and the expandable section (8) when in a collapsed state, however significantly smaller than the outer diameter of the expandable section (8) when in its expanded state. In this manner, when the expandable section (8) is situated inside the introducer (4), it will be kept in a collapsed state, but will expand as it reaches out of the distal opening of the introducer (4), being intravascularly positioned.

Fig. 4A shows the device (1) when introduced into a vasculature (2) where the expandable section being inside the introducer tube (5) is in a collapsed state, and Fig. 4B shows the situation when the device (1) is introduced for operation with the expandable section (8) keeping the sensor section (3) away from the vascular walls. Fig. 4C shows the situation where the device (1) is being removed and where the expandable section (8) collapses as it is retracted into the internal of the introducer tube (5).

One major aspect of the present invention is, that when introducing, removing and during operation of the device (1) when it is Wfully inserted into the body, then at any time all of the inner member (6) is in the inner lumen of and thus enclosed by the outer member (7). Further, this is in such a manner that the functional (or sensor) section (3) is positioned within the expandable section (8) of the outer member (7) during in vivo operation of the device (1). The ribs (10) may not be formed as straight lines, they may comprise at least first sections (17) running at a first angle and second sections (18) running at a second angle relative to an axis (19) parallel to the longitudinal direction of the extension of the expandable section (8) as seen in Fig. 5A, where the first (17) and the second (18) sections may be curved.

As seen in Fig. 5B, the rib elements (8) may also form a bifurcated and/or branched structure or network of rib elements (8) with at least first sections (17) running at a first angle and with sections (18) running at a second angle relative to an axis (19) parallel to the longitudinal direction of the extension of the expandable section.

Fig. 5A shows the ribs being formed by pure cuts, and Fig. 5B as areas being formed by cutting areas of material out of the tube (13), however, in any of the embodiments of this invention, the ribs may be formed in either manner, or even by a combination.

Figs. 6A-C illustrate a further embodiment of the present invention, where the device (1), or more specifically the outer member (7) is proximally equipped with a first connector (21 ) to match a second connector (22) of the introducer (4) in such a manner that the first and the second connectors (21 , 22) may be fixed to one another. Preferably the length of the outer member (7) from the first connector (21) to the expandable section (8) will match the length of the introducer (4) in such a manner, that when the first and the second connectors (21 , 22) are fixed to one another, the device (1) is fully inserted with the expandable section (8) extending out of the introducer (4). The connectors (21 , 22) may be of any kind known in the art, such as a lure cap with windings, a clamp system as illustrated in the Figs. 6A-C etc. The important thing is not how the connection is achieved, just the functionality of connecting the parts.

The connectors (21 , 22) may be attached to the introducer (4) and the outer member (7) in any manner known in the art, such as gluing etc. To enhance the affinity of the surface of especially the outer member (7) to the adhering material, such as glue, its surface roughness may have been increased, such as, but not limited to, by sandblasting.

Claims

1. Device (1) to be used in combination with an introducer (4) comprising an introducer tubular part (5), the device (1) comprising an outer member (7) and an inner member (6), the inner member (6) being positioned in the inner lumen of the outer member (7), where the device (1) distally further comprises an expandable section (8) able to expand in the radial direction, characterized in, the distal end of the outer member (7) is closed and has a substantially smooth surface.

2. Device (1) according to claim 1 , wherein inner member (6) comprises a functional section (3), and where the device (1) to be positioned through the skin of an animal such that the functional part during operation of the device (1) is in vivo to the animal, and where all in vivo positioned part of the inner member (6) is enclosed by the outer member (7).

3. Device (1) according to claim 2, wherein, when fully inserted the functional section (3) is enclosed within the expandable section (8).

4. Device (1) according to claim 3, wherein the expandable section (8) is formed by a plural of rib elements (10) having their proximal ends fixed (11) to the distal end of the main outer tube (13) and being connected to one another at their distal ends (12) where the distal ends of the rib elements form an outer distal tube (16) wherein the outer member (7), the rib elements (10) and the outer distal tube (16) are formed in a single body.

5. Device (1) according to claim 4, wherein the substantially smooth surface is formed by a plug (20) inserted into the distal end of the outer distal tube (16)

6. Device (1) according to claim 4, wherein the substantially smooth surface is formed by shaping (23) the distal end of the outer distal tube (16).

7. Device (1) according to any of the preceding claims, wherein the expandable section (8) in its expanded state has a diameter being substantially larger than the diameter of the outer member (7), and where the inner diameter of the introducer tubular part (5) is larger than the outer diameter of the outer member (7), but where the expanded diameter of the expandable section (8) is larger than the outer diameter of the introducer tubular part (5).

8. Device (1) according to any of the preceding claims, wherein at least the rib elements (10) are formed from a shape memory material.

9. Device (1) according to any of the preceding claims, where at the proximal end to be external to the skin the introducer (4) is equipped with a second connector (22) , and wherein the proximal end the of outer member (7) is fixed to a first connector (21), the first (21) and the second (22) connectors being adapted to fixed to one another, and where the length of the outer member (7) is such, that when the first and second connectors (21 , 22) are fixed to one another, the expandable section (8) extends out of the distal opening of the introducer (4).

10. Device (1) according to any of the preceding claims, wherein the functional section (3) is a semi-permeable section (3).

11. Device (1) according to any of the preceding claims, wherein the device (1) is introduced to the tissue through the inner conduit of the introducer tubular part (5) and where the expandable section (8) extends out of the distal opening of the introducer tubular part (5) when the device (1) is fully inserted.

12. Device (1) according to any of the preceding claims, wherein the

expandable section (8) is positioned within the inner conduit of the introducer tubular part (5) during insertion through the skin, but extends out of the distal opening of the introducer tubular part (5) being in an extended state during operation of the device (1).

13. Device (1) according to any of the claims 2-12, wherein the inner member (6) comprises at least two fluid conduits, one being adapted to transfer a fluid to the internal of the functional section (3), and the other to extract fluid from the functional section (3).

14. Device according to any of the claims 2-13, wherein the functional section (3) comprise supperters, such as for example metal threads of Nitenol or other materials comprising a substantial stiffness, and adapted to reduce bending of the functional section.