Deep venous arterialization (DVA) valvulotome

Abstract

A valvulotome device includes a cage having a proximal end, a distal end, and a longitudinal axis therebetween. The cage includes one or more struts which are radially openable to different diameters, and one or more cutting blades positioned on the one or more struts. A sheath is movable over the cage. Movement of the sheath exposes or covers the one or more struts. A wire extends distally beyond the distal end of the cage. The wire is fixedly coupled to the proximal end of the cage, and the distal end of the cage is free to slide over the wire.

Description

DEEP VENOUS ARTERIALIZATION (DVA) VALVULOTOMEFIELD OF THE INVENTION

[0001] The present invention generally relates to devices and methods for destroying venous valves, thereby enabling the vein to be used as an arterial bypass, or allowing reverse flow through the vein.BACKGROUND OF THE INVENTION

[0002] Peripheral vascular disease (PVD) mostly manifested as peripheral artery disease (PAD), includes all diseases caused by the obstruction of large arteries in the arms and legs.

[0003] Some patients suffering from Critical Limb Ischemia (CLI) present to their physicians with insufficient blood flow in their lower extremities. This disease can manifest itself from discomfort after walking to gangrenous toes and / or feet. A treatment method called Arterial- Venous (AV) reversal, or DVA (Deep Venous Arterialization), is used to supply blood to the foot through the deep venous system, which involves destruction of the vein valves near the foot to allow oxygenated blood flow into the foot.

[0004] Surgical bypass using the saphenous vein is also a way of treatment for severe PAD. The in-situ method of surgical bypass involves leaving the saphenous vein in its native bed and cutting the one-way check valves (a procedure known as a valvulotomy), which would normally ensure venous blood flow towards the heart. These valves are actually two semi-circular flaps formed from the vein's interior endothelial lining. Without these valves the surgeon is able to utilize the vein as an arterial conduit, in effect “arterializing” the vein.

[0005] Valvulotomes are medical catheters that are inserted into the vein and destroy venous valves, thereby enabling the vein to be used as an arterial bypass, or allow reverse flow through the vein.

[0006] Valvulotome devices can be rigid devices or flexible devices. Flexible valvulotomes are usually self-expandable and self-centering to adapt to the changing diameter of the vein and to remain centered in the vein. Both types are used mainly to treat veins after removal from the patient (for coronary bypass, for example). For use with veins that remain in the body and which can be used as arterial blood conduits,flexible valvulotome devices are usually inserted over a guidewire into the vein from its distal side and up, and cut the veins while being pulled backwards from the veins.

[0007] Until recently, all self-sizing and self-centering over-the-wire flexible valvulotomes cut the vein valves only while being pulled backwards inside the vein, and are thus described as pull valvulotomes (Figs. 1A-1B). The valvulotome cutting blades are folded and covered during insertion into the vein, and are then exposed to cut the valves while being pulled backwards in the vein. The sharp cutting edges of the cutting blades are designed to cut the vein valves only while being pulled backwards, so as not to damage the valves when being pushed into the vein.

[0008] Recently, a push valvulotome has been developed which cut the vein valves while being pushed into the vein. In this design, the cutting blades slide over the vein valves without damaging them when pulled back from the veins. This new type of reverse valvulotome or push valvulotome coming from above to cut the valves was developed to meet a need for treating Critical Limb Ischemia (CLI) patients that need to use their tibial veins near the foot as arterial conduits. Such a valvulotomy procedure is done after a guidewire is inserted from the artery into the vein, and the valvulotome is inserted over such guidewire.

[0009] US Patent Application 19950427808 (Vascutech Inc) describes a self-centering pull valvulotome having at least three radially mounted, retractable, cutting blades.

[0010] US Patent Applications US2016100855 (LeMaitre Vascular Inc) and US2013116500 (Andramed GmbH) describe over the wire self-centering valvulotomes, designed to cut valves through a wide range of vein diameters while the valvulotome is withdrawn backwards through the vessel.

[0011] US Patent Applications US2015366580 and US2017128704 (Limflow Inc), both describe a method of making the valves in the arterialized vein incompetent using a reverse (pull) valvulotome to cut the valves.

[0012] US Patent Application US2023052106 (Andramed GmbH) describe a flexible valvulotome having an expandable basket with cutting elements located on the basket arms. The basket is fixed to the distal end of a wire element to provide more empty space between the basket arms and to increase basket flexibility.SUMMARY

[0013] The present invention is directed to a device (valvulotome) and a method to perform vein valves destruction, for example, in order to use veins as arterial blood conduits. The device of the invention is a self-sizing, self-centering valvulotome designed to cut vein valves through a wide range of vein diameters and adjust to the internal diameter of the vein. The valvulotome of the invention includes a flexible long wire tip (guidewire tip) connected to its distal end, to provide proper navigation through the blood vessels and guide the device to the desired location. The valvulotome of the invention cuts the valve leaflets during backwards (withdrawn) movement inside the vein.

[0014] The valvulotome of the invention includes a catheter having a proximal end, a distal end, and a longitudinal axis therebetween, wherein at least one set of cutting blades are coupled to (that is, attached to or being part of) a flexible cage structure that can be opened to different diameters, thereby accommodating different vein diameters. An atraumatic resilient tip element (e.g., a cone) is coupled (e.g., bonded) to the flexible device wire tip near the cage distal end. A long tubular sheath is used to cover or uncover the flexible cage.

[0015] The method of using the valvulotome of the invention avoids using a separate guidewire to insert the valvulotome. Instead, the distal flexible long wire-tip of the valvulotome of the invention takes the place of a separate guidewire, so that the device itself can be properly inserted into the blood vessel and deployed to cut the valve leaflets. Avoiding a separate guidewire eliminates the need for a guidewire tube and a guidewire lumen in the valvulotome shaft, and more importantly, in the middle of the valvulotome flexible cage, enables reducing the device / folded cage diameter, which is critical for use in small curved veins. The smaller cage and more flexible construction increase the cage flexibility, which is important in small curved veins like foot heel veins that need to be treated for vein destruction in DVA procedures.

[0016] The flexible cage may be in a normally fully open position at maximal diameter. A sheath is slidably moveable over the flexible cage and over the plurality of cutting blades attached to the cage. The device is inserted and removed from the vein area while sheathed so as to keep the cutting blade(s) covered during device insertion and removal.An actuation mechanism engages the catheter at the proximal end to remove the sheath to uncover the cage and blades.

[0017] When using the valvulotome of the invention, the valvulotome is inserted using its flexible wire tip to support safe insertion into the blood vessel, and the flexible cage in the catheter distal end is folded inside the sheath, until reaching the vein area planned for vein valves destruction. Then the sheath is pulled backwards to expose the flexible cage and the cutting blades. Next, the valvulotome is pulled backwards along the section of the vein being treated, cutting the vein valves leaflets in every such motion. These movements can be repeated several times, if necessary.

[0018] The method of using the device of the invention may include using the flexible cage to catch a guidewire coming from the opposite direction. In some of the relevant procedure like DVA (Deep Venous Arterialization), after the vein valves are cut as described above, a standard guidewire coming from the opposite side of the vein, needs to be pulled in order to protrude from the same port at which the valvulotome was inserted. Instead of using special guidewire catching catheters for this purpose, in the present invention, the opposite guidewire tip may be inserted between the cage struts of the valvulotome of the invention. Struts of the device are then closed using the device sheath, thereby firmly holding the opposite guidewire for pulling it through the valvulotome entry point while removing the valvulotome.

[0019] There is provided in accordance with a non-limiting embodiment of the invention a valvulotome device including a cage having a proximal end, a distal end, and a longitudinal axis therebetween, the cage including one or more struts which are radially openable to different diameters, one or more cutting blades positioned on the one or more struts, a sheath movable over the cage, wherein movement of the sheath exposes or covers the one or more struts, and a wire that extends distally beyond the distal end of the cage, the wire being fixedly coupled to the proximal end of the cage, and wherein the distal end of the cage is free to slide over the wire.

[0020] In accordance with a non-limiting embodiment of the invention there is one the cutting blade for each of the one or more struts.

[0021] In accordance with a non-limiting embodiment of the invention there is more than one the cutting blade for at least one of the struts.

[0022] In accordance with a non-limiting embodiment of the invention an axial position of the one or more cutting blades is after a widest radial bulge of the one or more struts.

[0023] In accordance with a non-limiting embodiment of the invention an atraumatic element is coupled to the wire.

[0024] In accordance with a non-limiting embodiment of the invention the atraumatic element includes a radio-opaque marker.

[0025] There is provided in accordance with a non-limiting embodiment of the invention method for using a valvulotome device including providing a valvulotome device including: a cage having a proximal end, a distal end, and a longitudinal axis therebetween, the cage including one or more struts which are radially openable to different diameters, one or more cutting blades positioned on the one or more struts, a sheath movable over the cage, wherein movement of the sheath exposes or covers the one or more struts, and a wire that extends distally beyond the distal end of the cage, the wire being fixedly coupled to the proximal end of the cage, and wherein the distal end of the cage is free to slide over the wire, inserting the valvulotome device into a vein, moving the sheath to expose the one or more struts and the one or more cutting blades, moving the valvulotome device so that the one or more cutting blades cuts a portion of a vein valve, and moving the sheath to cover the one or more struts and the one or more cutting blades and removing the valvulotome device from the vein.

[0026] In accordance with a non-limiting embodiment of the invention cutting the portion of the vein valve is done during a deep venous arterialization procedure.

[0027] In accordance with a non-limiting embodiment of the invention the method further includes using the valvulotome device to capture and pull a guidewire, wherein the guide wire is inserted and held between the one or more struts, and then removing the valvulotome device from the vein while the guidewire is held between the one or more struts.BRIEF DESCRIPTION OF DRAWINGS

[0028] The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

[0029] Figs. 1A and IB are a simplified illustration and a medical image, respectively, of a prior art valvulotome cutting the vein valve leaflets.

[0030] Fig. 2 is a simplified photograph of a valvulotome device of the present invention, inserted through the foot plantar vein.

[0031] Fig. 3 is a simplified illustration of one embodiment of the valvulotome device of the invention.

[0032] Fig. 4 is a simplified illustration of another embodiment of the valvulotome device of the invention.

[0033] Fig. 5 is a simplified illustration of the valvulotome device of the invention being used to catch a guidewire coming from the opposite side.DETAILED DESCRIPTION

[0034] Figs. 1A-1B illustrate a prior art valvulotome designed to cut vein valves 2 through a wide range of diameters of a vein 1. The valvulotome cuts leaflets 3 of the valve 2 during backwards (withdrawn) movement inside the vein 1. As seen in Fig. 1A, the prior art valvulotome has an inner tube 8 for guiding the device over a guidewire. The prior art device is an over-the-wire valvulotome and a sheath keeps the cage closed while insertion into and from the blood vessel

[0035] Reference is now made to Fig. 3, which illustrates a valvulotome 10, in accordance with a non-limiting embodiment of the invention.

[0036] The valvulotome 10 may include a cage 12 having a proximal end 14, a distal end 15, and a longitudinal axis therebetween. The flexible cage 12 may include one or more cage arms or struts 13 (in the illustrated, non-limiting embodiment there are 3 or 4 struts), which can be opened to different diameters to accommodate different vein diameters. One or more cutting blades 16 are positioned on struts 13 (such as one blade per strut, or more than one blade per strut, or an alternative in which one or more struts have no cutting blades). The cutting blade 16 may be positioned on a distal portion of strut 13, meaning that the axial position of the blade is after the widest radial bulge of the strut. The cutting blade 16 may cut the vein valves leaflets when pulled backwards against the vein valves.

[0037] Cage 12 may be coupled (e.g., by adhesive, welding, or any other technique) to a wire 11 at its proximal end 14, whereas its distal end 15 can slide over wire 11, to allow opening and closing of the normally open cage 12 using a sheath 17. An atraumatic element 18 (such as an atraumatic cone 18) may be coupled (e.g., by adhesive, welding,or any other technique) to wire 11, close to distal end 15, leaving enough space for cage 12 and its distal end 15 to move when closing (contracting the struts of) cage 12, before reaching cone 18. The atraumatic element 18 may be made from, without limitation, from an elastomeric or polymeric material, or metal. The atraumatic element 18 may include a radio-opaque marker 27 to indicate the tip position within the blood vessel.

[0038] The flexible cage 12 is preferably made from a flexible metal tube, such as but not limited to, a nitinol tube, cut to form the one or more struts 13, and thermally shaped to a normally fully open position at a maximal diameter. Without limitation, the maximal cage open diameter may be up to 6 mm at the cage middle location. Blades 16 can be made as an integral part of struts 13, such as by laser cutting cage 12.

[0039] Sheath 17 slidably moves over the flexible cage arms 13 and the cutting blades 16 during insertion and removal of the valvulotome 10 into and from the vein, thereby safely keeping cutting blades 16 covered during device insertion and removal. The cage opening diameter is controlled by the sheath movement that uncovers the flexible cage 12. An actuation mechanism engages the catheter at the proximal end to move the sheath to cover or uncover the cage and blades.

[0040] The valvulotome 10 may be used for DVA Deep Venous Arterialization procedures, in which the device 10 is inserted through the distal posterior tibial vein or through the foot plantar vein and pushed up the tibial vein (as in Fig. 2). For use through such small veins and the foot tibial vein arch, the valvulotome 10 is very small and very flexible to pass and function through the foot tibial vein arch.

[0041] In use, upon reaching the upper desired location, the sheath 17 is pulled backward exposing the cage 12 with the cutting elements 16. Then the valvulotome 10 may be pulled back to cut the vein valves. In contrast to the prior art, the procedure is done without using a separate guidewire, because the distal flexible wire long tip 11 acts as the guidewire for the valvulotome 10 of the invention. This novel structure reduces both cost and time, and more importantly, enables constructing a very small diameter valvulotome that can be used in small distal tibial and plantar veins or other small veins whose valves need to be destroyed.

[0042] Cutting blades 16 are designed to cut the vein valve leaflets during withdrawal of the valvulotome. The leaflets face the sharp side 19 (Fig. 4) of the blade 16. Duringforward movement (the insertion direction) of the valvulotome 10, the vein or vein valve faces the non-cutting side 20 of blade 16 (Fig. 4), are thus not damaged. As described above, the blades 16 are positioned not at the open cage maximal diameter location, but rather at smaller open cage dimeter area as shown in Fig. 3 and 4, so they will not damage the vein walls, since the vein is opened by the cage at the maximal diameter location of the cage.

[0043] As mentioned above, valvulotome 10 of the invention is not inserted over a guidewire, because wire 11 acts as a guidewire. Without limitation, wire 11 may extend 10-50 cm distally from cage 12. Insertion and removal is done while the flexible cage 12 in the valvulotome 10 is folded inside sheath 17, After insertion through the blood vessels to the cutting site, sheath 17 is pulled backwards to expose flexible cage 12 and cutting blades 16, fully or partially. Flexible cage 12 tends to open to its normally fully open position, when sheath 17 is moved to expose the cage. Opening of cage 12 is also limited by the vein walls.

[0044] Blood flow or saline injected into the vein against the normal valve flow, may be used to ensure the valve leaflets are in a closed position, for better and more effective leaflet destruction, while using the valvulotome 10 of the invention.

[0045] Reference is now made to Fig. 5. In deep venous arterialization procedures, there is sometimes a need to catch and pull another guidewire 29 coming from another blood vessel. In the prior art, this is done using a special guidewire capturing catheter or a special balloon catheter coming from another blood vessel, such as the plantar vein or tibial vein.

[0046] The valvulotome 10 of the invention can be used for capturing and pulling the guidewire 29 coming from the artery. The tip or other portion of guidewire 29 may be inserted between the cage struts 13 of valvulotome 10. Afterwards the cage arms or struts 13 may be closed using the sheath 17, firmly holding guidewire 29 and pulling it through the valvulotome entry point when removing the valvulotome 10.

Claims

CLAIMS1. A valvulotome device comprising: a cage having a proximal end, a distal end, and a longitudinal axis therebetween, said cage comprising one or more struts which are radially openable to different diameters; one or more cutting blades positioned on said one or more struts; a sheath movable over said cage, wherein movement of said sheath exposes or covers said one or more struts; and a wire that extends distally beyond said distal end of said cage, said wire being fixedly coupled to said proximal end of said cage, and wherein said distal end of said cage is free to slide over said wire.

2. The valvulotome device according to claim 1 , wherein there is one said cutting blade for each of said one or more struts.

3. The valvulotome device according to claim 1, wherein there is more than one said cutting blade for at least one of said struts.

4. The valvulotome device according to claim 1, wherein an axial position of said one or more cutting blades is after a widest radial bulge of said one or more struts.

5. The valvulotome device according to claim 1, wherein an atraumatic element is coupled to said wire.

6. The valvulotome device according to claim 5, wherein said atraumatic element comprises a radio-opaque marker.

7. A method for using a valvulotome device comprising: providing a valvulotome device comprising: a cage having a proximal end, a distal end, and a longitudinal axis therebetween, said cage comprising one or more struts which are radially openable to different diameters; one or more cutting blades positioned on said one or more struts; a sheath movable over said cage, wherein movement of said sheath exposes or covers said one or more struts; and a wire that extends distally beyond said distal end of said cage, said wire being fixedly coupled to said proximal end of said cage, and wherein said distal end of said cage is free to slide over said wire; inserting said valvulotome device into a vein; moving said sheath to expose said one or more struts and said one or more cutting blades;moving said valvulotome device so that said one or more cutting blades cuts a portion of a vein valve; and moving said sheath to cover said one or more struts and said one or more cutting blades and removing said valvulotome device from the vein.

8. The method according to claim 7, wherein cutting the portion of the vein valve is done during a deep venous arterialization procedure.

9. The method according to claim 7, further comprising using said valvulotome device to capture and pull a guidewire, wherein said guidewire is inserted and held between said one or more struts, and then removing said valvulotome device from the vein while said guidewire is held between said one or more struts.

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