Methods and apparatus for vascular occlusion

Abstract

Implants for vascular occlusion comprise a membrane that is semipermeable to blood components when first implanted. The membrane may be configured to adsorb and / or hold blood cells to contribute to blood coagulation and / or granulation in the porous membrane during a blood-filling time period such that the membrane becomes substantially non-porous to blood flow after the time period. Thereafter, blood that is retained by the implant becomes coagulated and / or granulated into an occluding mass in the blood vessel.

Description

METHODS AND APPARATUS FOR VASCULAR OCCLUSIONRELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application 63 / 532,972 entitled Blood-Retaining Vascular Occluder filed on August 16, 2023 and to PCT Application PCT / US23 / 078414 filed on November 1 , 2023 entitled Porous membranes for Vascular Occlusion. The entire disclosures of all the related applications set forth in this section are hereby incorporated by reference in their entireties.FIELD

[0002] The present disclosure relates to vascular implants and methods for implanting vascular implants in a blood vessel, and more particularly, but not exclusively, to systems, devices and methods for forming a vascular occluder in blood vessels.BACKGROUND

[0003] Some medical procedures, such as embolization, involve occluding a blood vessel such as for reducing pressure on aneurysms, restricting a hemorrhage, or diminishing blood supply to tumors or growths in the body.

[0004] Vascular occlusion coils may be used for occluding or reducing blood flow in patient vasculature using endovascular coiling and embolization techniques. Such coils have a minute spiral body usually made of soft metal and are sized and configured for delivery and implantation using a catheter. One or more coils are delivered in a single site, then manually curled and packed together at the target implantation site until forming a structure which serves as a scaffold in which naturally coagulated blood forms to its surface for gradually causing local occlusion and embolization.

[0005] Vascular plugs are a different type of mechanical embolization device commonly used for occluding a targeted portion of vein or artery with a relatively low-profile delivery and can be released in a controlled fashion. One type of vascular plug includes balloon-like expandable devices that aim to immediately block and seal the blood vessel lumen locally for preventing blood from flowing therethrough upon expansion. Another type of vascular plug includes expandable meshed (woven or braided, for example) devices that depend on natural blood coagulation, which can develop gradually over time on surfaces of foreign artifacts until potentially forming local embolization. While the first plug type is more prone to issues of unintentional implant migration and gradual physical and / or functionaldegradation, the second plug type requires substantial time until forming effective blocking and is associated with recanalization phenomenon by which openings are formed in the thrombus over time.

[0006] There is a need for improved vascular occlusion devices for achieving improved results such as in one or more of: reducing time from deploying to blocking; reducing likelihood of unintentional implant migration; preventing or postponing physical and / or functional degradation; and preventing or postponing recanalization.

[0007] It should be noted that this Background is not intended to be an aid in determining the scope of the claimed subject matter nor be viewed as limiting the claimed subject matter to implementations that solve any or all of the disadvantages or problems presented above. The discussion of any technology, documents, or references in this Background section should not be interpreted as an admission that the material described is prior art to any of the subject matter claimed herein.SUMMARY

[0008] The present disclosure relates to vascular implants and methods for implanting vascular implants in a blood vessel, and more particularly, but not exclusively, to systems, devices and methods for forming a vascular occluder in a blood vessel.

[0009] In certain embodiments, there is provided a vascular occluder, which can comprise: (a) a vascular implant configured to define an enclosed space configured to contain a volume of blood, the vascular implant is radially expandable for engaging an inner wall surface of a blood vessel; and (b) a membrane provided at least at the proximal end and / or the distal end of the container, configured to cover most or all luminal cross-sectional area of the blood vessel when the occluder engages the inner wall surface thereof.

[0010] In some embodiments, the membrane is configured to allow blood to flow therethrough into a defined volume during a predetermined blood-filling period after the occluder is radially expanded and engages the inner wall surface of the blood vessel, and then to prevent blood from flowing therethrough from the defined volume, thereby retaining the volume of blood in the defined volume when the volume of blood coagulates and / or granulates.

[0011] In some embodiments, the vascular occluder is configured to induce granulation tissue formation by the volume of blood retained in the defined volume.

[0012] In some embodiments, the vascular occluder is configured to induce blood coagulation in and / or on the membrane during the blood-filling period.

[0013] In some embodiments, the membrane is configured to adsorb and / or hold cells of blood passing therethrough associated with causing or contributing to blood coagulation and / or granulation, during the blood-filling period.

[0014] In some embodiments, the membrane is configured to adsorb blood-clotting proteins, such as fibrinogen and albumin.

[0015] In some embodiments, the membrane is configured to promote adhesion, activation, and aggregation of platelets.

[0016] In some embodiments, the membrane is configured as a thin fluid-permeable three-dimensional network structure.

[0017] In some embodiments, the membrane comprises a porous fluid-permeable random or aligned, three-dimensional network of polymeric microfibers and / or nanofibers.

[0018] In some embodiments, the three-dimensional network of polymeric microfibers and / or nanofibers is configured with average fiber diameter smaller than about 5 micrometer, optionally smaller than about 2 micrometer, and / or average pore size smaller than about 50 micrometer and / or within a range of about 1 micrometer to about 50 micrometer.

[0019] In some embodiments, the membrane is formed by way of electrospinning.

[0020] In some embodiments, the porous membrane is provided both at the proximal end and at the distal end of the container.

[0021] In some embodiments, most or all surface of an expandable structure is connected to, coated over, or impregnated with the membrane.

[0022] In some embodiments, the vascular occluder further comprising a container expanding and / or anchoring element configured to expand the container to over the local inner diameter of the blood vessel and / or to maintain the container radially pressed against the inner wall surface of the blood vessel for anchoring the container thereto.

[0023] In some embodiments, the container expanding and / or anchoring element is configured for selective filling of the container space for affecting radial expansion and / or anchoring of the container.

[0024] In some embodiments, the container expanding and / or anchoring element comprises a flexible member having an elastically stretchable three-dimensional frame structure.

[0025] In some embodiments, the container includes a flexible tubular wall that is optionally meshed, woven, braided or perforated.

[0026] In some embodiments, the flexible tubular wall is formed of metallic material such as Ni-Ti alloy, optionally in a form of braided wire.

[0027] In some embodiments, the predetermined blood-filling period is smaller than about 90 seconds, optionally particularly smaller than about 60 seconds, optionally particularly smaller than about 30 seconds, optionally particularly smaller about 10 seconds, or optionally particularly smaller about 5 second.

[0028] In some embodiments, the predetermined blood-filling period is smaller than a minimally achievable result in a local activated clotting time (ACT) type test of coagulation.

[0029] In some embodiments, the container space is undivided so as to promote formation of a single coagulated or granulated mass sized to fill most or all of the container space for occluding the blood vessel.

[0030] In certain embodiments, there is provided a method for occluding a blood vessel. The method may comprise: positioning the vascular occluder in a blood vessel; expanding the device such that the device engages a wall of the blood vessel; allowing blood to flow through a membrane to fill the container space until the membrane is at least 75% clogged with blood cells and / or coagulated blood preventing blood from flowing therethrough, so as to retain a volume of blood in the occluder; and retaining the volume of blood in the occluder space during coagulation and / or granulation thereof into a single coagulated or granulated mass sized to fill most or all of the container space for occluding the blood vessel.

[0031] In some embodiments, the membrane is configured to completely clog within the predetermined blood-filling period less than about 90 seconds.

[0032] In some embodiments, the expanding is configured in size and / or magnitude sufficient for causing local inflammation such as by way of stretching the blood vessel wall and / or preventing oxygenation thereof.

[0033] In some embodiments, the expanding includes filling a container space with a three-dimensional frame structure.

[0034] In another embodiment, a vascular occluder comprises a first occluder portion comprising a first membrane, wherein the first occluder portion is configured to engage a first location on an inner wall surface of a blood vessel. The vascular occluder also comprises a second occluder portion comprising a second membrane, wherein the second occluder portion is configured to engage a second location on the inner wall surface of the blood vessel axially spaced along the blood vessel from the first location.

[0035] In some embodiments, the first occluder portion and the second occluder portion are both configured to, when implanted, cover most or all of the cross-sectional area of the blood vessel at the first and second locations with the first and second membranes.

[0036] In some embodiments, the first and second membranes are substantially porous to blood flow prior to implantation and are configured to induce blood coagulation in and / or on the membranes after implantation.

[0037] The first membrane and the second membrane may be configured to allow blood to flow therethrough during a predetermined blood-filling period and then to substantially prevent blood from flowing therethrough.

[0038] The first occluder portion and the second occluder portion may each comprise an expandable frame structure to which the first and second membranes are coupled. The first and second occluder portions may be configured to self-expand when released from a delivery lumen.

[0039] In another embodiment, a method for occluding a blood vessel comprises positioning a vascular occluder comprising a first occluder portion and a second occluder portion onto axially separate locations and radially expanding the first and second occluding portions of the vascular occluder such that each engages the wall of the blood vessel, allowing blood to flow through at least the first occluder portion to a segment of the blood vessel between the first and second occluding portions until at least the first occluding portion is at least 75% clogged with blood cells and / or coagulated so as to retain a volume of blood in the segment of the blood vessel, and retaining the volume of blood in the segment of the blood vessel during coagulation and / or granulation thereof into a single coagulated or granulated mass sized to fill most or all of the segment of the blood vessel.

[0040] It is understood that various configurations of the subject technology will become apparent to those skilled in the art from the disclosure, wherein various configurations of the subject technology are shown and described by way of illustration. As will be realized,the subject technology is capable of other and different configurations and its several details are capable of modification in various other respects, all without departing from the scope of the subject technology. Accordingly, the summary, drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Various embodiments are discussed in detail in conjunction with the Figures described below, with an emphasis on highlighting the advantageous features. These embodiments are for illustrative purposes only and any scale that may be illustrated therein does not limit the scope of the technology disclosed. These drawings include the following figures, in which like numerals indicate like parts.

[0042] FIG. 1 is a cross section of a blood vessel in which a vascular occluder may be deployed therein.

[0043] FIG. 2 shows the blood vessel of FIG. 1 with a vascular occluder initially deployed therein according to some embodiments.

[0044] FIG. 3 shows the vascular occluder of FIG. 1 some time after deployment.

[0045] FIG. 4 shows the vascular occluder of FIG. 1 a longer time after deployment.

[0046] FIG. 5 is a side view illustrating one embodiment of the expandable structure of the vascular occluder of FIG. 1 .

[0047] FIG. 6 shows a deployment lumen for a vascular occluder in a blood vessel.

[0048] FIG. 7A shows an embodiment of a vascular occluder inside the deployment lumen of FIG. 6.

[0049] FIG. 7B shows the vascular occluder of FIG. 7A after deployment from the deployment lumen.

[0050] FIG. 7C shows a close up of part of FIG. 7B.

[0051] FIG. 7D shows the vascular occluder of FIGs. 7B detached from the delivery lumen.

[0052] FIGs. 8A and 8B illustrate a vascular occluder with a supplemental occlusion coil.

[0053] FIGs. 9A and 9B illustrate a vascular occluder with openings in the membrane for facilitating occluder removal.

[0054] FIGs. 10A, 10B, 10C, and 10D illustrate a process of removing a previously installed vascular occluder.

[0055] FIG. 11 shows the blood vessel of FIG. 1 with another embodiment of a vascular occluder deployed therein.

[0056] FIG. 12 shows the vascular occluder of FIG. 11 some time after deployment.

[0057] FIG. 13 shows the vascular occluder of FIG. 12 a longer time after deployment.

[0058] FIG. 14A illustrates one embodiment of an expandable structure of the vascular occluder of FIG. 11 .

[0059] FIG. 14B illustrates another embodiment of an expandable structure of the vascular occluder of FIG. 1 1 .

[0060] FIGs. 15A and 15B show vascular occluders with connected first and second portions.

[0061] FIG. 16A shows another embodiment of a vascular occluder inside the deployment lumen of FIG. 6.

[0062] FIG. 16B shows the vascular occluder of FIG. 16A after deployment from the deployment lumen.

[0063] FIG. 17A shows another embodiment of a vascular occluder inside the deployment lumen of FIG. 6.

[0064] FIG. 17B shows the vascular occluder of FIG. 17A after deployment from the deployment lumen.

[0065] FIG. 18A shows still another embodiment of a vascular occluder inside the deployment lumen of FIG. 6.

[0066] FIG. 18B shows the vascular occluder of FIG. 18A after deployment from the deployment lumen.

[0067] FIG. 18C shows the vascular occluder of FIG 18B after further manual expansion of the vascular occluder inside the blood vessel.

[0068] FIG. 19A shows yet another embodiment of a vascular occluder inside the deployment lumen of FIG. 6.

[0069] FIG. 19B shows the vascular occluder of FIG. 19A after deployment from the deployment lumen.

[0070] FIG. 20 shows vascular occluders according to some embodiments deployed in blood vessels.DETAILED DESCRIPTION

[0071] The following description and examples illustrate some exemplary implementations, embodiments, and arrangements of the disclosed invention in detail. Those of skill in the art will recognize that there are numerous variations and modifications of this invention that are encompassed by its scope. Accordingly, the description of a certain example embodiment should not be deemed to limit the scope of the present invention.

[0072] Certain embodiments relate to vascular implants and methods for implanting vascular implants in a blood vessel, and more particularly, but not exclusively, to systems, devices and methods for forming a vascular occluder in blood vessels. In some embodiments, a vascular occluder comprises a first occluder portion and a second occluder portion configured to engage axially separated different locations in a blood vessel.

[0073] FIG. 1 illustrates a blood vessel comprising a lumen 20 having a luminal cross- sectional area defined by a blood vessel wall with blood flow shown by arrow 23 from an upstream portion 26 to a downstream portion 28. FIG. 2 shows the blood vessel of FIG. 1 having a vascular occluder 10a according to some embodiments of the invention implanted therein. Vascular occluder 10a includes an expandable structure 12a having a membrane 11 a coupled thereto.

[0074] The vascular occluder 10a may be considered to have three portions, a proximal portion 27, a distal portion 39, and a medial portion 31 between the proximal portion 27 and the medial portion 29. For the occluder 10a design of FIG. 2, the proximal portion 27 is the portion intended for upstream deployment, the distal portion is the portion at the other end intended for downstream deployment, and the medial portion 31 is intended to be engaged with the blood vessel wall 22 when the occluder 10a is deployed. As described further below, the expandable structure 12a and / or the membrane 11 a may have different characteristics from each other in these three regions. In some implementations, the medial region 31 may have no membrane 11 a on it at all.

[0075] Membrane 11 a and expandable structure 12a may be in a variety of forms, sizes or shapes. The embodiment illustrated in FIG. 2 is a closed container-like form. Expandable structure 12a is configured to unfold and / or spread membrane 1 1 a selectively, manually, or automatically, such that membrane 1 1 a can cover most or all of luminal cross section area enclosed by a wall 22 of the blood vessel 20 it is deployed in. “Most or all” in this contextbeing preferably at least 75% of the luminal cross-sectional area, more preferably at least 90% of the luminal cross-sectional area, and more preferably still at least 95% of the luminal cross-sectional area. In some embodiments, expandable structure 12a and the associated membrane 11 a are sized or selected in a size sufficient to cause local radial expansion or stretching of the host blood vessel wall 22 after deployment for anchoring membrane 1 1a and / or expandable structure 12a to the blood vessel wall 22, to press tight membrane 1 1 a and / or expandable structure 12a against the blood vessel wall, and / or to cause or induce inflammation of the blood vessel wall 22. As will be described in more detail below, one or more delivery devices may be detachably connected to the vascular occluders described herein and may be optionally configured for delivery and positioning of a vascular occluder in a target blood vessel and may optionally be configured to facilitate manual manipulation expandable structure 12a and associated membrane 1 1 a. For example, the occluder 10a may be delivered in a folded or collapsed configuration and then unfolded and / or expanded to the state shown in FIG. 2.

[0076] At least one or more portions of membrane 11 a shown in cross hatch in FIG. 2 may be configured as a thin, fluid-permeable, three-dimensional network structure having an average thickness less than about 1 mm, optionally less than about 500 micrometer, optionally less than about 100 micrometer, optionally less than about 10 micrometer, or optionally less than about 5 micrometer. These portions of membrane 11 a may optionally comprise a fluid-permeable random or aligned, three-dimensional network of polymeric microfibers and / or nanofibers, optionally formed by way of electrospinning. The three- dimensional network of polymeric microfibers and / or nanofibers is optionally configured with average fiber diameter smaller than about 5 micrometer, optionally smaller than about 2 micrometer, or optionally equal to or smaller than about 1 micrometer. The three- dimensional network of polymeric microfibers and / or nanofibers is optionally configured with an average pore size smaller than about 50 micrometer, optionally within a range of about 1 micrometer to about 20 micrometer.

[0077] In some embodiments, at least one or more portions of the membrane 11 a are configured as a microfiber and / or nanofiber membrane comprising a three-dimensional network of polymeric microfibers and / or nanofibers. Such a three-dimensional network may in some embodiments be made by commercially known and available electrospinning manufacturing processes. In some such embodiments, prior to deployment and exposureto blood in the vessel 20 such portions of the membrane 11 a have a porous and fluid- permeable sponge-like structure that may in some embodiments be characterized by an initial relatively high porosity, large specific surface area, small pore size, good channel connectivity, and ease of functional modification. In some embodiments, at least one or more portions of membrane 1 1 a are configured as a 3D electrospun fibrous sponge constructed by 3D build-up of electrospun fiber layers. In some such embodiments, at least one or more portions of fibrous membrane 11 a are made via electrospinning, homogenization, shaping and thermal crosslinking, and exhibits high porosity, water absorption and compression resilience.

[0078] The occluder 10a of FIG. 2 defines a volume or contained space 13a inside the expandable structure 12a. At least one or more portions of the membrane 11 a have some porosity to flow of blood components therethrough prior to deployment, preferably significant porosity to flow of blood components therethrough prior to deployment. Thus, after initial expansion and deployment is accomplished as shown in FIG. 2, blood will continue to flow (although potentially with some reduction) from the upstream portion 26 of the blood vessel to the downstream portion 28 of blood vessel through the proximal portion 27 and distal portion 29 of membrane 11 a as indicated by arrows 24 and 25 respectively.

[0079] At least one or more portions of membrane 11 a is advantageously configured to only temporarily allow blood to flow therethrough into and out of volume 13a. This blood flow may be present during a predetermined blood-filling period. The predetermined bloodfilling period may be optionally smaller than about 90 seconds, optionally particularly smaller than about 60 seconds, optionally particularly smaller than about 30 seconds, optionally particularly smaller about 10 seconds, or optionally particularly smaller than about 5 seconds.

[0080] At least one or more portions of membrane 11 a may further be configured to change its permeability to blood flow (e.g., to clog) during the blood-filling period, and afterwards to substantially prevent blood from flowing therethrough into and from volume 13a thereby retaining a volume of blood in volume 13a sufficiently for allowing natural coagulation of the retained volume of blood to thrombosis, and / or natural granulation thereof to granulated tissue. At least one or more portions of membrane 11 a may be configured to initiate, promote and / or accelerate coagulation and / or granulation of the retained blood volume into a single coagulated or granulated mass that is sized to fill mostor all of volume 13a for occluding the blood vessel. “Most or all” in this context being preferably at least 75% of the volume 13a, more preferably at least 90% of the volume 13a, and more preferably still at least 95% of the volume 13a. FIG. 3 shows the occluder 10a at or near the end of the blood filling period, where the membrane 1 1 a has substantially blocked blood flow therethrough and an amount of blood is retained in volume 13a.

[0081] To produce this change in blood flow permeability, at least one or more portions of membrane 11 a is optionally configured to adsorb and / or hold cells present in blood passing therethrough that are associated with causing or contributing to blood coagulation and / or granulation, during the blood-filling period, including blood-clotting proteins such as fibrinogen and albumin. The adsorption of proteins can be the initiating event in the processes occurring when blood contacts some or all of the surface of membrane 11 a, which can lead to thrombus formation. Alternatively or additionally, at least one or more portions of membrane 11 a are optionally configured to promote adhesion, activation, and aggregation of platelets.

[0082] In certain advantageous embodiments, the at least one or more portions of membrane 1 1 a is formed as a 3D web of fibers having non-linear and in some cases even tortuous pathways therethrough that define potentially different porosities of at least one or more portions of the membrane 11 a to different components of blood. When initially deployed upon release from a delivery catheter, e.g., immediately prior to the configuration shown in FIG. 2, the expandable structure 12a will be in a collapsed state with small internal volume. From this collapsed state, the expandable structure 12a will expand and the volume 13a inside the membrane 1 1 a and expandable structure 12a will increase, generating a negative pressure inside the expandable structure 12a. At least one or more portions of the membrane 1 1 a may be initially semipermeable to blood components and this negative pressure in conjunction with the porosity of at least some portions of membrane 11 a can draw blood components through at least some portions of the membrane 11 a and into the volume 13a. At least some portions of the membrane 11 a may be semipermeable to red blood cells, allowing blood plasma and an initial percentage of red blood cells surrounding the membrane to enter the volume 13a. This initial percentage will be more than 0% and less than 100% of the surrounding red blood cells and may advantageously be between 20% and 80% of the surrounding red blood cells. This red- blood cell migration partial limiting property can produce a volume of blood inside theoccluder 10a with a reduced concentration of red blood cells. The red blood cells that are pulled onto or into at least one or more portions of the membrane 1 1 a but don’t pass all the way through become trapped on the entrances of or inside the pathways through the mesh structure, which further reduces the size of the pathways through the mesh of these membrane 1 1 a portions and therefore further reduces the permeability of these portions of the membrane 11a to the flow of blood components. A similar process occurs with other components of blood such as platelets, proteins such as albumin, fibrinogen, and globulin, and other blood components to which at least some portions of the membrane 11 a are also semipermeable when initially deployed. At least some portions of the membrane 1 1 a may also be more permeable to platelets than red blood cells. The semipermeable nature of the at least some portions of the membrane 1 1 a may therefore produce within the volume 13a a volume of blood that is relatively rich in platelets and proteins such as fibrinogen relative to red blood cells. Over the course of the blood filling period described above, the permeability of at least some portions of the membrane 11a decreases due to the pathways through the 3D mesh of the membrane becoming increasingly blocked by trapped blood components and potentially clotting / thrombus formation inside the at least some portions of the membrane 11 a until at the end of the blood filling period the at least some portions of the membrane 11 a are substantially impermeable to flow of blood components therethrough and a volume of blood is trapped and stagnant inside volume 13a. This trapped volume of blood in volume 13a may subsequently form a thrombus which may then form into granulated tissue that is essentially impervious to recanalization, thereby permanently blocking flow through blood vessel 20.

[0083] Membrane characteristics that have been found suitable to produce this functionality may include a mean fiber diameter (where fiber diameter refers to non-clumped filaments visible under microscopy) in the 0.2 micron to 2 micron range with a standard deviation in the distribution of the fiber diameters in the range of 10% to 50% of the mean. In some embodiments, the mean fiber diameter is in the range of 0.6 to 1 .6 microns, and at least 90% of the fibers have a diameter in the range of 0.5 microns and 3 microns. In general, the distribution of fiber diameters may be such that 90% of the fibers have a diameter between 0.5 times the mean and 2 times the mean. In some advantageous embodiments, the mean thickness of the membrane on the expandable structure may be 3-300 times the mean fiber thickness. In some advantageous embodiments, the meanmembrane thickness is in the range of 3-10 times the mean fiber diameter. For fibrous mesh membranes such as described herein, mean pore sizes are typically defined by a measure of the dimensions of open or dark two-dimensional areas between the filaments in straight-on 2D electron micrographs of a membrane. Measured in this manner (which may be referred to as the 2D pore area), suitable membrane pore areas for membrane 1 1a have been found to have mean pore areas in the range of 0.5 to 20 square microns. This corresponds to approximate mean pore diameters (where a 2D pore diameter is defined as the diameter of a circle having the same 2D pore area of a given measured pore) in the range of about 0.6 microns to 5 microns. In particular, a mean pore area of 2-10 square microns has been found suitable, which corresponds to mean pore diameters of about 1 .5 microns to 3.5 microns. It can be advantageous to provide a wide range of 2D pore areas in the membrane such as a mean between 2 and 10 square microns with 90% of the pores having an area between 1 and 50 square microns. In general, the membrane may have a distribution of 2D pore areas wherein at least 90% of the pores have a 2D pore area between 0.25 times the mean 2D pore area and 5 times the mean 2D pore area. In some embodiments, the mean 2D pore diameter may be between 1 micron and 4 microns with 90% of the pores having a 2D pore diameter between 0.5 microns and 9 microns.

[0084] Given that red blood cells are disk shaped with about an 8 micron diameter and 2 micron thickness, it will be appreciated that to pass through the advantageous membranes described herein, a red blood cell may require a particular orientation relative to the membrane surface, and may need to change direction around or over one or more fibers to pass through a non-linear 3D channel in the membrane 11 a. Red blood cells with the wrong orientation or that enter a channel that becomes too restricted will become trapped on the outer surface or partly or wholly inside the membrane 1 1 a. A 3D web structure of, for example, three to ten layers thick of 0.5 to 1 .5 micron mean fiber diameter and a 0.5 to 20 square micron mean pore area can generate the desired semipermeable to red blood cells quality exhibited by the membrane 11a. The same is true of platelets and other cells such as fibroblasts. These may interact with the membrane 1 1a similarly to red blood cells, but with, for example, the smaller platelet cells passing through the membrane in a higher percentage than red blood cells. Platelets, although passing more easily through the fiber web of the membrane, may aggregate inside and on the surface of the membrane 1 1 a in response to the initial sticking and trapping of red blood cells on and inside the 3D mesh ofthe membrane 11 a. Thus, initial aggregation of red blood cells will trigger the aggregation of platelets and fibrin generation, which will trigger further clumping of red blood cells, initiating a chain reaction of clotting on and in the membrane that will gradually reduce the membrane permeability over the blood filling period and that will continue after the blood filling period. Generally, the “blood filling period” may be defined as the period beginning when the occluder is first released into the vessel 20 from a delivery catheter until the rate of inflow and outflow of red blood cells and platelets drops to be less than 25% of the initial rate of inflow and outflow of red blood cells and platelets respectively.

[0085] Accordingly, vascular occluder 10a can be deployed and implanted in a blood vessel (vein or artery) for forming a mass sized for occluding the blood vessel 20. A method for reaching such a result may include one or more of (not necessarily in same order): (a) positioning the occluder 10a in a blood vessel; (b) unfolding and / or spreading the membranel 1 a to cover most or all the luminal cross section area enclosed by a wall 22 of the blood vessel; (c) allowing blood to flow through membranes 1 1 a to fill volume 13a until the membrane 11 a is substantially clogged (e.g. at least 75% clogged, optionally at least 90% clogged) with blood cells and / or coagulated blood, thereby preventing blood from flowing therethrough, so as to retain a volume of blood in volume 13a; (d) optionally causing local inflammation such as by way of stretching the blood vessel wall and / or preventing oxygenation thereof; and (e) retaining the volume of blood in the volume 13a during clotting, thrombosis, and / or granulation thereof into a mass sized to fill most or all of volume 13a for occluding the blood vessel.

[0086] Referring again to FIG. 2, membrane 1 1 a may be unfolded or spread by expansion of the expandable structure 12a adjacent thereto, such that the membrane 1 1 a covers most or all of the luminal cross section area enclosed by wall 22 of blood vessel 20 which is the configuration shown in FIG. 2. Once unfolded or spread but still substantially unclogged (e.g., less than 75% clogged, or less than 50% clogged), the membrane 1 1a allows blood to flow into the volume 13a, while adsorbing, capturing, or retaining blood cells and proteins associated with causing or contributing to blood coagulation and / or granulation. Expandable structure 12a is configured to allow blood flow therethrough, and is optionally formed of meshed (e.g., braided) structure with sufficiently large openings for facilitating greater permeability and / or less resistance blood flow therethrough relative to membrane 11 a. As shown, expandable structure 12a once expanded may be configuredto cause local radial expansion or stretching of the host blood vessel wall 22, anchoring membrane 1 1 a to the blood vessel wall 22, to press tight membrane 1 1 a against the blood vessel wall 22, and / or to cause or induce local inflammation at or near implant location 5 in blood vessel wall 22.

[0087] As shown in FIG. 3, after the blood-filling period, which may take between a few seconds to about 90 seconds, for example, membrane 1 1 a can be substantially or completely clogged, such that blood is prevented from flowing therethrough into and out of volume 13a. This results in blocking flow of blood in blood vessel 20 and retaining a certain volume of blood in volume 13a which is subjected to natural coagulation and / or granulation process. In some embodiments, a delivery device (not shown) that was used to deliver and deploy the occluder to the location 5 can be disconnected and fully or partly removed from blood vessel 20, and this can be executed before or after membrane 11 a is substantially clogged.

[0088] FIG. 4 shows vascular implant 10a after several days, weeks, or months following implantation thereof in blood vessel 20, after natural coagulation and / or granulation of retained blood in volume 13a. In some embodiments, vascular occluder 10a is configured to allow, cause, or promote natural formation of a single formed mass of granulation tissue and / or thrombosis filling most or all of volume 13a occluding blood vessel 20. In some embodiments, causing inflammation in blood vessel 20, such as by way of stretching blood vessel wall 22 and / or preventing oxygenation thereof with expandable structures 12a, causes, induces or promotes particularly the formation of granulation tissue within entire volume 13a. One possible advantage of a single granulation tissue formed mass is its prevention of large sized recanalization that can allow renewed effective blood flow in blood vessel 20.

[0089] In some embodiments, a beneficial aspect of the membranes and membrane portions described above is that at the end of the blood filling period, e.g. at the time illustrated in FIG. 3, the vessel is substantially occluded, and in addition the volume 13a inside the occluder 10a contains cells, proteins, and other blood components that provide support for forming not just a thrombus, but granulation tissue as well. This may be accomplished because complete occlusion is caused by biological processes that clog the membrane or portions thereof while at the same time allowing the trapping certain blood components that are beneficial to creating a permanent and fixed biomechanical structureformed from the combination of the expandable structure 12a, the membrane 11 a, and the biological material trapped inside the volume 13a.

[0090] FIG. 5 shows one possible implementation of the expandable structure 12a for the occluder 10a without the membrane 1 1a coupled thereto. The expandable structure in this embodiment is in the form of an expandable mesh container that may be formed from braided wires or a cut shell. The expandable structure 12a has a proximal portion 27, a distal portion 29, and a medial portion 31. As shown in FIGs. 2 through 4, the expandable structure 12a is covered over at least some of its surface with the membrane 11 a. In some embodiments, the expandable structure 12a is completely or substantially completely covered by membrane 1 1 a. In some embodiments there may be a portion 33 of the central section 31 that is not covered by membrane 11 a or covered by a thinner membrane layer. This section 33 may comprise some or all of the portion of the expandable structure 12a that is engaged with the vessel wall 22 and therefore need not have the membrane functionality described herein.

[0091] Different portions of the membrane 1 1 a may have different configurations and / or properties at different locations on the expandable structure. The semipermeable portion that clogs during the blood filling time period with the fiber diameters, pore dimensions, thicknesses, and the like described above need not cover the entire expandable structure 12a in some embodiments, but may be localized to functionally significant parts of the occluder surface. The semipermeable portion as described above may be provided at least on the proximal portion 27 of the occluder 10a that is exposed to the upstream portion of the vessel 20. To keep the volume 13a enclosed and the volume of biological material therein trapped, a membrane portion will also be provided on the distal portion 29 of the occluder, although the portion of membrane 11 a in this region 29 may be less permeable or even substantially impermeable to blood components even when initially deployed such it clogs faster or may not require clogging at all over the blood filling period to keep the volume 13a sufficiently enclosed. However, it can be advantageous for the membrane 1 1 a portions on both the proximal portion 27 of the occluder 10a and the distal portion 29 of the occluder 10a to be provided with the same or similar semipermeable membrane material having the construction and properties described above. The medial region 31 is less critical, and as noted above, may have no membrane coupled thereto at all. A cloggingsemipermeable membrane 1 1 a with construction and functional properties described above may, for example, cover 20% to 100% of an occluder surface.

[0092] FIG. 6 illustrates a deliver catheter with a proximal portion 52 which is maintained external to the patient and a distal portion 54 thereof which is provided in a lumen of target blood vessel 20 (catheter 52, 54 is shown in a side view, and blood vessel 20 is shown in a side cross-sectional view for ease of description). The distal portion 54 of the catheter has a distal end designated A in FIG. 6, which is where the occluder to be implanted resides before deployment. Such a delivery catheter can be used to deliver all of the occluder embodiments described herein. A wide variety of delivery mechanisms and techniques have been developed and continue to be developed to deploy stents, plugs, coils, ballons, and the like into patient vasculature. Any such techniques can be applied to the occluders described herein and any specific methods described below are only some example techniques that may be possible to employ for some embodiments.

[0093] FIGs. 6 and 7A-7D schematically illustrate exemplary scenarios representing steps in a method for forming a vascular occluder 10a in a target blood vessel 20. FIG. 6 shows a first scenario wherein catheter with a distal portion 54 thereof is provided in a lumen of target blood vessel 20 (catheter is shown in a side view, and blood vessel 20 is shown in a side cross-sectional view for ease of description). FIG. 7A illustrates catheter distal portion 54 in an enlarged side cross-sectional view. Expandable structure 12a is provided and / or deliverable in a crimped or radially compacted configuration in a lumen of catheter (optionally particularly in distal portion 54). Expandable structure 12a is pushable and optionally releasably connected to an elongated pusher 56 (such as by way of threading or snap-locking) which optionally extends along the lumen such that a proximal end thereof is manipulatable by a user via a proximal portion of catheter.

[0094] FIG. 7B shows a second scenario wherein expandable structure 12a is pushed via pusher 56 into the lumen of target blood vessel 20 (or equivalently is held in place with pusher 56 as the distal portion 54 of the delivery catheter is withdrawn in the direction of arrow 60 in FIG. 7A. FIG. 7C illustrates expandable structure 12a connected to pusher 56 emerging via distal portion 54 in an enlarged side cross-sectional view. Expandable structure 12a is allowed to elastically expand creating a contained space 13a, optionally until engaging a side wall thereof with vessel wall 22 inner surface of target blood vessel 20. In some embodiments, the user can choose expandable structure 12a of a specific sizeand / or shape in accordance with some fitting consideration thereof in target blood vessel 20. Expandable structure 12a may be formed as a tubular or other shaped structure by way of one or more wires which may be braided or otherwise arranged and coupled as is known in the art, optionally metal wires (e.g., Ni-Ti or Co-Cr alloy wires), although it can be made by other materials, optionally non-stretching wires, such as nylon, polyester, cotton, polypropylene or aramid. As described above although not shown in FIGs. 7a-7D, the expandable structure 12a is advantageously fully or partially covered or impregnated with another material, optionally in a form of coating layers or a membrane. The mesh of expandable structure 12a is advantageously configured with openings to be permeable to liquids for allowing or facilitating blood from target blood vessel 20 to flow therethrough into expandable structure 12a. Optionally, additionally or alternatively, one or more openings on or next to the side wall are configured to allow inflow of blood into expandable structure 12a and / or outflow of blood from expandable structure 12a. In some embodiments, expandable structure 12a is configured such that it cannot be effectively inflated by gas and / or liquid, and / or that it is configured to self-expand while allowing fluid flow thereinto.

[0095] FIG. 7D illustrates the system after vascular occluder 10a is disconnected from pusher 56 and after catheter 54 is removed from blood vessel 20, leaving vascular occluder 10a in place.

[0096] FIGS. 8A and 8B illustrate the occluder 10a of FIGs. 1 -4 supplemented with an occlusion coil to assist expansion and anchoring of the device to the vessel wall 22. Expandable structure 12a in the form of a container may be configured to self-expand to a certain state when under relatively small resistance, such as within a lumen of a blood vessel 20 however without significant strength to locally expand or stretch radially the blood vessel wall. Vascular occluder 10a may then further include a container expanding and / or anchoring element 37 configured to expand container 12a to greater than the local inner diameter of a host blood vessel 20 and / or to maintain container 12a radially pressed against the inner wall surface of the blood vessel for anchoring container 31 thereto. Container expanding and / or anchoring element 37 may include a flexible member having an elastically stretchable a three-dimensional frame structure configured for selective filling of container space 13a for affecting radial expansion and / or anchoring of container 12a. In some embodiments, the container expanding and / or anchoring element 36 may comprise anocclusion coil in accordance with the various occlusion coil embodiments known and used in the art.

[0097] Container expanding and / or anchoring element 37 may be introduced into volume 13a via a delivery device and through a dedicated opening in porous membrane 32. Element 37 may be delivered in an elastically stretched form and may then be allowed to elastically regain a more volume expanded three-dimensional form in volume 13a, however it is still restricted from forming its maximally expanded unstressed three-dimensional frame structure. Therefore, element 37 applies a continuous radial or volumetric pressure on container 12a thereby forcing it to further expand radially together with membrane 1 1a against the blood vessel wall. In some embodiments, element 37 is configured to apply sufficient pressure through container 12a onto blood vessel wall such that the latter expands laterally, and in some particular embodiments this causes sufficient stretching of blood vessel wall and / or diminishes oxygenation thereof so as to cause or induce local inflammation. In some embodiments, this additional expansion under stress of container 12a increases pressure difference which causes suction of blood components into container space 13a via membrane 11 a during the blood filling period described above.

[0098] FIGs. 9A and 9B schematically illustrate a cross-sectional view of occluder 10a having a particular membrane 11 a configuration that can facilitate removal of a previously installed occluder. This embodiment of vascular occluder 10a may be similar or identical in most or all structural and / or functional embodiments to vascular occluder 10a of FIGs. 1 -4 and 8A-8B other than that it also includes one or more blood extraction openings 39 in membrane 11 a. This embodiment includes container 12a, membrane 11 a, container space 13a, and container expanding and / or anchoring element 37, and is optionally releasably connectable to a delivery device. Blood extraction openings 39 are configured to allow ejection of blood from container space 13a to the host blood vessel when container 12a is pressurized such as by extraction thereof by external force. This embodiment can be found advantageous for example when, after initial deployment and substantial clogging of membrane 11 a, a user wishes to remove or reposition vascular occluder 10a. In some embodiments, blood extraction openings 39 are provided at lateral portions configured for engaging blood vessel wall when container 12a is expanded using element 37, such that openings 39 are covered by the blood vessel wall when container 12a is pressed against it. In some embodiments, blood extraction openings 39 are configured as through holes, cuts,septum valves or pressure relief valves. In some embodiments, blood extraction openings 39 are about 1 mm or less, optionally 0.5 mm or less in diameter.

[0099] FIGs. 10A - 10D schematically illustrate exemplary scenarios representing steps in a method for extracting vascular occluder 10a from blood vessel 20. FIG. 10A represents a possible exemplary scenario in which vascular occluder 10a is already deployed in blood vessel 20, whereas container space 13a is substantially or completely filled with retained blood components, and membrane 11 a is substantially or fully clogged (e.g., over than about 75% clogged, optionally over 90% clogged) with coagulated blood (e.g., covering it and / or built up across its thickness such as including within its pores) so as to retain the already present volume of blood components in container space 13a. Since the container 12a presses against wall 22 of blood vessel 20 and blood extraction openings 39 are clogged or blocked by the blood vessel wall 22, the retained blood components in volume 13a cannot escape the volume 13a.

[0100] FIG. 10B represents a possible scenario following a decision to remove or reposition vascular occluder 10a after the earlier scenario shown in FIG. 10A, in which a first step would be to remove element 37 from occupying container space 13a that functions to expand container 12a to press against blood vessel wall 22. This may cause immediate initial contraction of container 12a and / or uncovering of blood extraction openings 39. Depending on one or more variables, such as the effective opened area of blood extraction openings 39, the internal pressure within container space 13a, and / or the viscosity of the retained volume of blood components within container space 13a, blood may already begin to exit from container space 13a via openings 39 at this stage.

[0101] An ejection of blood from container space 13a via openings 39 in substantial magnitude can be accomplished when vascular occluder 10a is pulled back into lumen of delivery device 54 (or another device or instrument), as shown in FIG. 10C. This process causes an extraction of vascular occluder 10a and forces retained blood components in volume 13a to eject from container space 13a into blood vessel 20 through the blood extraction openings 39, due to the increased internal pressure in container space 13a as derived from the pulling force applied to container 12a. Substantial or complete emptying of the retained blood components from container space 13a can be accomplished once vascular occluder is fully withdrawn into delivery device 54, as suggested in FIG. 10D.

[0102] Another embodiment of a vascular occluder 10b with similar functionality to the vascular occluder 10a described above is illustrated in FIGs. 1 1 through 13. As shown in FIG. 11 , this embodiment of a vascular occluder 10b comprises a first occluder portion 32 engaged with the blood vessel wall at a first location 4. The vascular occluder 10b further comprises a second occluder portion 34 engaged with the blood vessel wall at a second location 6. The second location 6 is axially spaced from the first location 4 along the blood vessel wall 22. The first occluder portion 32 comprises an expandable structure 12b having a membrane 11 b coupled thereto. Similarly, the second occluder portion 34 comprises an expandable structure 12c having a membrane 11 c coupled thereto.

[0103] Membranes 11 b, 1 1 c and / or expandable structures 12b, 12c may be in any chosen form, size or shape, such as a disk-like form (as shown), dome-like form, closed container-like form, or otherwise. Expandable structures 12b and 12c are configured to unfold and / or spread membranes 1 1 b and 1 1 c, selectively or automatically, such that membranes 1 1 b, 1 1 c can each cover most all or luminal cross section area enclosed by a wall of the blood vessel it is deployed in. “Most or all” in this context being preferably at least 75% of the luminal cross-sectional area, more preferably at least 90% of the luminal cross- sectional area, and more preferably still at least 95% of the luminal cross-sectional area. In some embodiments, expandable structures 12b, 12c and the associated membranes 1 1 b and 11 c are sized or selected in a size sufficient to cause local radial expansion or stretching of the host blood vessel wall 22 after deployment for anchoring membranes 1 1 c and 11 d to the blood vessel wall 22, to press tight membranes 1 1 b and 11 c against the blood vessel wall, and / or to cause or induce inflammation.

[0104] As noted above, one or more delivery devices may be detachably connected to the vascular occluders described herein and may be optionally configured for delivery and positioning of a vascular occluder in a target blood vessel and may optionally be configured to facilitate manual manipulation of one or both expandable structures 12b and 12c and associated membranes 1 1 b and 11 c. For example, the first and second occluder portions 32, 34 may be delivered in a folded or collapsed configuration and then unfolded and / or expanded to the state shown in FIG. 1 1 .

[0105] The axially spaced occluder portions 32, 34 define a volume 13b in the segment of the blood vessel between the first occluder portion 32 at the first location 4 and the second occluder portion 34 at the second location 6. The membranes 1 1 b and 1 1 c may beconfigured as described above with respect to membrane 11 a. That is, membranes 1 1 b and 11 c have at least some porosity to blood component flow therethrough prior to deployment, preferably significant porosity to blood flow therethrough prior to deployment. Thus, when first deployed as shown in FIG. 11 , blood will continue to flow (although potentially with some reduction) from the upstream portion 26 of the blood vessel to the downstream portion 28 of blood vessel through the membranes 11 b and 1 1 c as indicated by arrows 24 and 25 respectively.

[0106] Membranes 1 1 b and 11 c may further be configured to change their permeability to blood flow (e.g., to clog) during the blood-filling period, and afterwards to substantially prevent blood from flowing therethrough into and from volume 13b thereby retaining a volume of blood in volume 13b sufficiently for allowing natural coagulation of the retained volume of blood to thrombosis, and / or natural granulation thereof to granulated tissue.

[0107] Membranes 11 a and 11 b may be configured to initiate, promote and / or accelerate coagulation and / or granulation of the retained blood volume into a single coagulated or granulated mass that is sized to fill most or all of volume 13b, for occluding the blood vessel. “Most or all” in this context being preferably at least 75% of the volume 13b, more preferably at least 90% of the volume 13b, and more preferably still at least 95% of the volume 13b. FIG. 12 shows the first occluder portion 32 and second occluder portion 34 near or at the end of the blood filling period, where the membranes 1 1 a and 1 1 b have substantially blocked blood flow therethrough and an amount of blood is retained in volume 13.

[0108] In some embodiments, vascular occluder 10b can be deployed and implanted in a blood vessel (vein or artery) for forming a mass sized for occluding the blood vessel. A method for reaching such a result may include one or more of (not necessarily in same order): (a) positioning the second occluder portion 34 and the first occluder portion 32 in a blood vessel; (b) unfolding and / or spreading the membranes 1 1 a and 11 b to cover most or all the luminal cross section area enclosed by a wall of the blood vessel; (c) allowing blood to flow through porous membranes 1 1a and 1 1 b to fill volume 13b until the porous membranes 1 1 a and 11 b are substantially clogged (e.g. at least 75% clogged, optionally at least 90% clogged) with blood cells and / or coagulated blood, thereby preventing blood from flowing therethrough, so as to retain a volume of blood in volume 13b; (d) optionally causing local inflammation such as by way of stretching the blood vessel wall and / or preventing oxygenation thereof; and (e) retaining the volume of blood in the volume 13b during clotting,thrombosis, and / or granulation thereof into a mass sized to fill most or all of volume 13b for occluding the blood vessel.

[0109] Referring again to FIG. 1 1 , each membrane 1 1 b, 11 c may be unfolded or spread by expansion of the expandable structure 12b, 12c adjacent thereto, such that each membrane 11 b, 11 c covers most or all of the luminal cross section area enclosed by wall 22 of blood vessel 20 which is the configuration shown in FIG. 1 1 . Once unfolded or spread but still substantially unclogged (e.g., less than 75% clogged, or less than 50% clogged), the membranes 11 b, 11 c allow blood to flow through the volume 13b between them, while adsorbing, capturing, or retaining blood cells associated with associated with causing or contributing to blood coagulation and / or granulation. Expandable structures 12b and 12c are configured to allow blood flow therethrough, optionally, and are optionally formed of meshed (e.g., braided) structure with sufficiently large openings for facilitating greater permeability and / or less resistance blood flow therethrough relative to membranes 1 1 b and 11 c. As shown, expandable structures 12a and 12b once expanded may be configured to cause local radial expansion or stretching of the host blood vessel wall 22, anchoring porous membranes 11 b and 11 c to the blood vessel wall 22, to press tight membranes 1 1 b and 11 c against the blood vessel wall 22, and / or to cause or induce inflammation.

[0110] As shown in FIG. 12, after the blood-filling period, which may take between a few seconds to about 90 seconds, for example, membranes 11 b and 11 c can be substantially or completely clogged, such that blood is prevented from flowing therethrough into and out of volume 13b. This results in blocking flow of blood in blood vessel 20 and retaining a certain volume of blood in volume 13b which is subjected to natural coagulation and / or granulation process. In some embodiments, a delivery device (not shown) that was used to deliver and deploy the first occluder portion 32 and second occluder portion 34 to the first position 4 and second position 6 respectively can be disconnected and fully or partly removed from blood vessel 20, and this can be executed before or after membranes 1 1 b and 1 1 c are substantially clogged.

[0111] FIG. 13 shows vascular implant 10b after several days, weeks, or months following implantation thereof in blood vessel 20, after natural coagulation and / or granulation of retained blood in volume 13b. In some embodiments, vascular occluder 10b is configured to allow, cause, or promote natural formation of a single formed mass of granulation tissue and / or thrombosis filling most or all of volume 13b occluding blood vessel20. In some embodiments, causing inflammation in blood vessel 20, such as by way of stretching blood vessel wall 22 and / or preventing oxygenation thereof with expandable structures 12b and 12c, causes, induces or promotes particularly the formation of granulation tissue within entire volume 13b. One possible advantage of a single granulation tissue formed mass is its prevention of large sized recanalization that can allow renewed effective blood flow in blood vessel 20.

[0112] FIGs. 14A and 14B show example constructions for the expandable structures 12b / 12c for first occluder portion 32 and second occluder portion 34 without showing the membranes 11 b and 11 c attached thereto. Expandable structures 12b and 12c may be formed by way of one or more wires which may be braided or otherwise arranged and coupled as is known in the art, optionally metal wires (e.g., Ni-Ti or Co-Cr alloy wires), although it can be made by other materials, optionally non-stretching wires, such as nylon, polyester, cotton, polypropylene or aramid. In the embodiment of FIG. 14A, the expandable structures 12b and 12c are essentially the closed ends 27 and 29 of the container 12a illustrated in FIG. 5 which may in these embodiments be deployed separately or together. In the embodiment of FIG.14B, wires are formed as spokes extending radially outward from a central section. The spokes may fold inward near the central portions so that the first and second occluder sections 32, 34 can be folded down (like an umbrella for example) for placement in a delivery lumen that will be threaded to the desired location in the vasculature. In the embodiment of FIG. 14B, the spokes may or may not extend all the way to or beyond the radial extent of the membranes 1 1 b and 11 c. In other embodiments, the spokes or possibly other portions of the expandable structures 12b and 12c extend radially farther out than the membranes 11 b and 11 c. This may be useful for anchoring the occluder portions 32, 34 to the blood vessel wall in some embodiments. The expandable structures 12b and 12c can be in a mesh form or any of a wide variety of alternative arrangements. It may be preferable to use a minimum amount of material so as to make the occluder portions 32, 34 more flexible and more easily navigated through narrow and potentially tortuous pathways along blood vessels to the desired implant locations 4, 6.

[0113] In FIGs. 1 1 -14, the expandable structure 12b for the first occluder portion 32 is shown and described as substantially identical to the expandable structure 12c for the second occluder portion 34 but this need not be the case. As specific examples, depending on the application, one may be stiffer or less stiff, include more or less wires than the other,have a different wire pattern, extend farther radially or less far, one may be fully selfexpanding and the other manually expanded after implantation. Other variations would also be possible.

[0114] The occluder portions 32 and 34 in FIGs. 11 -13 are shown in schematic cross section as having membrane material surrounding the expandable structures on both sides thereof. It will be appreciated however, that the membrane material may be deposited on either single side of an expandable structure as well.

[0115] As with the expandable structures 12b, 12c, the membrane 1 1 b for the first occluder portion 32 is shown and described as substantially identical to the expandable structure 1 1 c for the second occluder portion 34 but this need not be the case. Depending on the application, one may have different pore sizes, porosity, filament diameters, thickness, or the like from the other. For example, the occluder portion to be installed downstream in the blood vessel may be configured with smaller average pore sizes or fewer pores so as to clog faster than the occluder portion to be installed upstream in the blood vessel. The same considerations discussed above with respect to the proximal portion 27 and distal portion 29 of the container style embodiment shown in FIGs. 1 -3 are applicable to the proximal membrane 11 b and distal membrane 11 c as well.

[0116] FIG. 15A shows a vascular occluder 10c with a first portion 32 and a second portion 34 similar to the vascular occluder 10b of FIG. 11. However, the embodiment of FIG. 15A further provides a connection element 15 that couples the expandable structure 12b to expandable structure 12c. This connection element may comprise a wire that facilitates maintaining the spacing between the first occluder portion 32 and second occluder portion 34 during and potentially after deployment. The ends of the wire may, for example, be coupled to the central portions of the expandable structures respectively. For installation into a delivery catheter, the first occluder portion 32 may fold inward to the right in FIG. 15A over the connection element 15 and the second occluder portion 34 may fold inward to the left in FIG. 15B over the connection element.

[0117] FIG. 15B shows another embodiment of expandable structures 12b and 12c coupled by a connection element 15. As with FIGs. 5, 7A-7D, the membranes 11 b, 1 1 c couped to the expandable structures are not illustrated but would cover substantially all of the structures 12b and 12c shown in FIG. 15B.

[0118] FIG. 16A and 16B illustrate an example deployment method for the vascular occluder 10b of FIGs. 1 1 -14. FIG. 16A illustrates the catheter of FIG. 6 having distal end “A” of distal portion 54 in an enlarged side cross-sectional view with vascular occluder 10b installed therein. The first occluder portion 32 and second occluder portion 34 are provided and / or deliverable in a crimped or radially compacted configuration as shown by the arrows in a lumen of catheter 54. In some embodiments, the folding / compaction of the first occluder portion 32 and second occluder portion 34 will be more than that shown in FIG. 16A. FIGs. 16A and 16B illustrate the separate deployment of self-expanding embodiments of the first occluder portion 32 and second occluder portion 34. The distal end of the catheter may be pulled back in the direction of arrow 60 while holding the first occluder portion 32 and second occluder portion 34 in place in the vessel with the pusher 56 as the catheter is pulled back over them until the second occluder portion 34 is exposed and exits the catheter tip due to the retreating catheter tip at location 6. The second occluder portion 34 may then self-expand to seat itself tightly against the blood vessel wall 22. For example, the expandable structure for this occluder portion 34 may be pre-stressed nitinol configured to open at body temperature. Then, both the catheter and the pusher can be pulled back together until the end of the catheter with the first occluder portion 32 still retained inside is at or near location 4 of the blood vessel, thereby establishing the desired spacing 36 between the first occluder portion 32 and second occluder portion 34 and the desired volume 13. The catheter distal tip may then again pulled back while holding the first occluder portion 32 in place with the pusher 56 until the first occluder portion 32 is exposed and exits the catheter tip due to the retreating catheter tip at location 4. As occurred with the second occluder portion 34, the first occluder portion 32 may then self-expand to seat itself tightly against the blood vessel wall 22. For example, the expandable structure for this occluder portion 32 may also be pre-stressed nitinol configured to open at body temperature.

[0119] FIGs. 17A and 17B illustrate a different deployment scenario where the first occluder portion 32 and second occluder portion 34 are held a desired distance apart inside the deployment catheter by a connection element 15 such as shown in FIG. 15. In this case, the entire occluder can be held in place with the pusher 56 as the catheter is pulled back in the direction of arrow 60 from both the second occluder portion 34 and the first occluder portion 32 in one continuous motion.

[0120] FIGS. 18A, 18B, and 18C illustrate a deployment scenario where manual expansion of the first occluder portion 32 and second occluder portion may be performed. In this embodiment, the delivery catheter includes both a pusher 56 and a deployment wire 14 coupled to the central portions of the two expandable structures. To fully deploy the vascular occluder, the distal tip of the delivery catheter is pulled back exposing both occluder portions, which expand to at least slightly engage the blood vessel wall (not shown). Then, the deployment wire 14 is pulled back in the direction of arrow 61. In this scenario, the engagement of the circumferences of the occluder portions with the blood vessel wall may hold the circumferences of the occluder portions in place as the deployment wire 14 pulls their central regions to the left in FIG. 18B, thereby pushing the circumferences further outward to more tightly engage the blood vessel wall as illustrated in FIG. 18C. Following this, the proximal portion of the deployment wire may be detached at coupler 58.

[0121] Another deployment scenario is illustrated in FIGs. 19A and 19B. In this embodiment, the deployment catheter is pulled back to expose the first occluder portion 32 and the second occluder portion 34 similar to FIG. 18A and 18B. In the configuration of FIGs. 19A and 19B however, the deployment wire is pulled in the direction of arrow 61 to only deploy the second occluder portion 34, whereas the pusher 56 is pushed in the direction of arrow 62 to deploy the first occluder portion 32.

[0122] It will be appreciated that a wide variety of deployment strategies may be employed with single or multiple deployment and manipulation wires possible that may connect to the inner or outer portions of the expandable structures.

[0123] Referring now to FIG. 20, advantageous configurations of vascular occluders as described above define a segment of blood vessel 20 having a length 74 and a volume 13 that exists between the first occluder portion 32 and the second occluder portion 34 which is substantially empty of occluder components and contains only trapped blood that can coagulate to securely block blood flow in the vessel. Although this length 74 and volume 13b can have some deployment or spacing components provided in it, it may be unoccupied by any cage or braided wires in this region. This can foster the formation of granular tissue in the volume 13b with low risk of either recanalization or migration. Furthermore, this is accomplished with less required material, which facilitates delivery of the occluder to the desired site through narrow and tortuous vasculature. The length 74 may be at least 50% of the total extent 76 of the occluder, optionally at least 75% of the total extent of theoccluder. In some embodiments, at least 90% of the total extent of the occluder is provided by this inner region 74 that is substantially devoid of occluder components.General Interpretive Principles for the Present Disclosure

[0124] Various aspects of the novel systems, apparatuses, and methods are described more fully hereinafter with reference to the accompanying drawings. The teachings disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the novel systems, apparatuses, and methods disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, a system or an apparatus may be implemented, or a method may be practiced using any one or more of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such a system, apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect disclosed herein may be set forth in one or more elements of a claim. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to particular benefits, uses, or objectives. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.

[0125] With respect to the use of plural vs. singular terms herein, those having skill in the art can translate from the plural to the singular and / or from the singular to the plural as is appropriate to the context and / or application. The various singular / plural permutations may be expressly set forth herein for sake of clarity.

[0126] When describing an absolute value of a characteristic or property of a thing or act described herein, the terms “substantial,” “substantially,” “essentially,” “approximately,” and / or other terms or phrases of degree may be used without the specific recitation of a numerical range. When applied to a characteristic or property of a thing or act describedherein, these terms refer to a range of the characteristic or property that is consistent with providing a desired function associated with that characteristic or property.

[0127] In those cases where a single numerical value is given for a characteristic or property, it is intended to be interpreted as at least covering deviations of that value within one significant digit of the numerical value given.

[0128] If a numerical value or range of numerical values is provided to define a characteristic or property of a thing or act described herein, whether or not the value or range is qualified with a term of degree, a specific method of measuring the characteristic or property may be defined herein as well. In the event no specific method of measuring the characteristic or property is defined herein, and there are different generally accepted methods of measurement for the characteristic or property, then the measurement method should be interpreted as the method of measurement that would most likely be adopted by one of ordinary skill in the art given the description and context of the characteristic or property. In the further event there is more than one method of measurement that is equally likely to be adopted by one of ordinary skill in the art to measure the characteristic or property, the value or range of values should be interpreted as being met regardless of which method of measurement is chosen.

[0129] It will be understood by those within the art that terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are intended as “open” terms unless specifically indicated otherwise (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.).

[0130] It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and / or “an” should typically be interpreted to mean “at leastone” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations).

[0131] In those instances where a convention analogous to “at least one of A, B, and C” is used, such a construction would include systems that have A alone, B alone, C alone, A and B together without C, A and C together without B, B and C together without A, as well as A, B, and C together. It will be further understood by those within the art that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include A without B, B without A, as well as A and B together.”

[0132] Various modifications to the implementations described in this disclosure can be readily apparent to those skilled in the art, and generic principles defined herein can be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the disclosure is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the claims, the principles and the novel features disclosed herein. The word “exemplary” is used exclusively herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.

[0133] Certain features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features can be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination can be directed to a sub-combination or variation of a sub-combination.

[0134] The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and / or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions may be modified without departing from the scope of the claims.

[0135] Each of the following terms written in singular grammatical form: 'a', 'an', and 'the', as used herein, means 'at least one', or 'one or more'. Use of the phrase 'one or more' herein does not alter this intended meaning of 'a', 'an', or 'the'. Accordingly, the terms 'a', 'an', and 'the', as used herein, may also refer to, and encompass, a plurality of the stated entity or object, unless otherwise specifically defined or stated herein, or, unless the context clearly dictates otherwise. For example, the phrases: 'a unit', 'a device', 'an assembly', 'a mechanism', 'a component', 'an element', and 'a step or procedure', as used herein, may also refer to, and encompass, a plurality of units, a plurality of devices, a plurality of assemblies, a plurality of mechanisms, a plurality of components, a plurality of elements, and, a plurality of steps or procedures, respectively.

[0136] Each of the following terms: 'includes', 'including', 'has', 'having', 'comprises', and 'comprising', and, their linguistic I grammatical variants, derivatives, or / and conjugates, as used herein, means 'including, but not limited to', and is to be taken as specifying the stated component(s), feature(s), characteristic(s), parameter(s), integer(s), or step(s), and does not preclude addition of one or more additional component(s), feature(s), characteristic(s), parameter(s), integer(s), step(s), or groups thereof. Each of these terms is considered equivalent in meaning to the phrase 'consisting essentially of.

[0137] The term 'method', as used herein, refers to steps, procedures, manners, means, or / and techniques, for accomplishing a given task including, but not limited to, those steps, procedures, manners, means, or / and techniques, either known to, or readily developed from known steps, procedures, manners, means, or / and techniques, by practitioners in the relevant field(s) of the disclosed invention.

[0138] Throughout this disclosure, a numerical value of a parameter, feature, characteristic, object, or dimension, may be stated or described in terms of a numerical range format. Such a numerical range format, as used herein, illustrates implementation of some exemplary embodiments of the invention, and does not inflexibly limit the scope of the exemplary embodiments of the invention. Accordingly, a stated or described numericalrange also refers to, and encompasses, all possible sub-ranges and individual numerical values (where a numerical value may be expressed as a whole, integral, or fractional number) within that stated or described numerical range. For example, a stated or described numerical range 'from 1 to 6' also refers to, and encompasses, all possible subranges, such as 'from 1 to 3', 'from 1 to 4', 'from 1 to 5', 'from 2 to 4', 'from 2 to 6', 'from 3 to 6', etc., and individual numerical values, such as '1 ', '1 .3', '2', '2.8', '3', '3.5', '4', '4.6', '5', '5.2', and '6', within the stated or described numerical range of 'from 1 to 6'. This applies regardless of the numerical breadth, extent, or size, of the stated or described numerical range.

[0139] Moreover, for stating or describing a numerical range, the phrase 'in a range of between about a first numerical value and about a second numerical value', is considered equivalent to, and meaning the same as, the phrase 'in a range of from about a first numerical value to about a second numerical value', and, thus, the two equivalently meaning phrases may be used interchangeably. For example, for stating or describing the numerical range of room temperature, the phrase 'room temperature refers to a temperature in a range of between about 20 °C and about 25 °C, and is considered equivalent to, and meaning the same as, the phrase 'room temperature refers to a temperature in a range of from about 20 °C to about 25 °C.

[0140] When applied to a numerical value, the term 'about', as used herein, refers to ± 10 % of the stated numerical value.

[0141] It is to be fully understood that certain aspects, characteristics, and features, of the invention, which are, for clarity, illustratively described and presented in the context or format of a plurality of separate embodiments, may also be illustratively described and presented in any suitable combination or sub-combination in the context or format of a single embodiment. Conversely, various aspects, characteristics, and features, of the invention which are illustratively described and presented in combination or sub-combination in the context or format of a single embodiment, may also be illustratively described and presented in the context or format of a plurality of separate embodiments.

[0142] Although the invention has been illustratively described and presented by way of specific exemplary embodiments, and examples thereof, it is evident that many alternatives, modifications, or / and variations, thereof, will be apparent to those skilled in the art.Accordingly, it is intended that all such alternatives, modifications, or / and variations, fall within the spirit of, and are encompassed by, the broad scope of the appended claims.

Claims

WHAT IS CLAIMED IS:1 . A vascular occluder, comprising: a vascular implant configured to create an enclosed space when engaged with an inner wall surface of a blood vessel, wherein the enclosed space is configured to contain a volume of blood, wherein the vascular implant is radially expandable for engaging the inner wall surface of the blood vessel; and a membrane provided on some or all of the vascular implant and configured to cover most or all luminal cross-sectional area of the blood vessel when the vascular implant is engaged with the inner wall surface thereof, wherein the membrane is configured to allow blood to flow therethrough into the enclosed space during a predetermined blood-filling period after the vascular implant is radially expanded and engages the inner wall surface of the blood vessel, and then to prevent blood from flowing therethrough from the enclosed space, thereby retaining the volume of blood in the enclosed space as the volume of blood coagulates and / or granulates.

2. The vascular occluder of claim 1 , configured to induce granulation tissue formation by the volume of blood retained in the enclosed space.

3. The vascular occluder of claim 1 , configured to induce blood coagulation in and / or on the porous membrane during the blood-filling period.

4. The vascular occluder of claim 1 , wherein the membrane is configured to adsorb and / or hold cells of blood passing therethrough associated with causing or contributing to blood coagulation and / or granulation, during the blood-filling period.

5. The vascular occluder of claim 1 , wherein the membrane is configured to adsorb blood-clotting proteins, such as fibrinogen and albumin.

6. The vascular occluder of claim 1 , wherein the membrane is configured to promote adhesion, activation, and aggregation of platelets.

7. The vascular occluder of claim 1 , wherein the membrane is configured as a thin fluid-permeable three-dimensional network structure.

8. The vascular occluder of claim 1 , wherein the membrane comprises a porous fluid-permeable random or aligned, three-dimensional network of polymeric microfibers and / or nanofibers.

9. The vascular occluder of claim 8, wherein the three-dimensional network of polymeric microfibers and / or nanofibers is configured with average fiber diameter smaller than about 5 micrometer, optionally smaller than about 2 micrometer, and / or average pore size smaller than about 50 micrometer and / or within a range of about 1 micrometer to about 50 micrometer.

10. The vascular occluder of claim 9, wherein the average fiber diameter is smaller than about 2 micrometers and the average pore size is within a range of about 1 micrometer to about 50 micrometers.

11. The vascular occluder of claim 9, wherein the membrane is formed by way of electrospinning.

12. The vascular occluder of claim 11 , wherein the average fiber diameter is smaller than about 2 micrometers and the average pore size is within a range of about 1 micrometer to about 50 micrometers.

13. The vascular occluder of any preceding claim, wherein the membrane is provided both at the proximal end and at the distal end of the vascular implant.

14. The vascular occluder of any preceding claim, wherein most or all surface of the vascular implant is connected to, coated over, or impregnated with the membrane.

15. The vascular occluder of any preceding claim, wherein the predetermined bloodfilling period is smaller than about 90 seconds, optionally particularly smaller than about 60 seconds, optionally particularly smaller than about 30 seconds, optionally particularly smaller about 10 seconds, or optionally particularly smaller about 5 second.

16. The vascular occluder of any preceding claim, wherein the predetermined bloodfilling period is smaller than a minimally achievable result in a local activated clotting time (ACT) type test of coagulation.

17. The vascular occluder of any preceding claim, wherein the vascular occluder further comprises a container with an expanding and / or anchoring element configured to expand the container to over the local inner diameter of the blood vessel and / or to maintain the container radially pressed against the inner wall surface of the blood vessel for anchoring the container thereto.

18. The vascular occluder of claim 17, wherein the container expanding and / or anchoring element is configured for selective filling of the container space for affecting radial expansion and / or anchoring of the container.

19. The vascular occluder of any one of claims 17 or 18, wherein the container expanding and / or anchoring element comprises a flexible member having an elastically stretchable three-dimensional frame structure.

20. The vascular occluder according to any one of claims 17-19, wherein the container expanding and / or anchoring element comprises a vascular occlusion coil.

21. The vascular occluder of claim 19, wherein arced segments of the vascular occlusion coil engage a side wall of the container.

22. The vascular occluder of any preceding claim, wherein the vascular implant comprises a container with a side wall that is optionally meshed, woven, braided or perforated.

23. The vascular occluder according to claim 22, wherein the side wall is formed of metallic material such as Ni-Ti alloy, optionally in a form of braided wire.

24. A method for occluding a blood vessel, the method comprising: positioning a vascular occluder according to any preceding claim in a blood vessel; radially expanding the vascular occluder such that the vascular occluder engages a wall of the blood vessel; allowing blood to flow through the membrane to fill the enclosed space until the membrane is at least 75% clogged with blood cells and / or coagulated blood preventing blood from flowing therethrough, so as to retain a volume of blood in the enclosed space; and retaining the volume of blood in the enclosed space during coagulation and / or granulation thereof into a single coagulated or granulated mass sized to fill most or all of the enclosed space for occluding the blood vessel.

25. The method according to claim 24, wherein the membrane is configured to completely clog within the predetermined blood-filling period less than about 90 seconds.

26. The method according to any one of claims 24 or 25, wherein the expanding is configured in size and / or magnitude sufficient for causing local inflammation such as by way of stretching the blood vessel wall and / or preventing oxygenation thereof.

27. The method according to any one of claims 24-26, wherein the expanding includes filling the enclosed space with a three-dimensional frame structure.

28. A vascular occluder, comprising: a first occluder portion comprising a first membrane, wherein the first occluder portion is configured to engage a first location on an inner wall surface of a blood vessel; a second occluder portion comprising a second membrane, wherein the second occluder portion is configured to engage a second location on the inner wall surface of the blood vessel axially spaced along the blood vessel from the first location.

29. The vascular occluder of claim 28, wherein the first occluder portion and the second occluder portion are both configured to, when implanted, cover most or all of the cross-sectional area of the blood vessel at the first and second locations with the first and second membranes.

30. The vascular occluder of any one of claims 28 or 29, wherein the first and second membranes are substantially porous to blood flow prior to implantation.31 .The vascular occluder of any one of claims 28-30, wherein the first and second membranes are configured to induce blood coagulation in and / or on the membranes after implantation.

32. The vascular occluder of any one of claims 28-31 , wherein the first and second membranes are configured to adsorb and / or hold cells of blood passing therethrough associated with causing or contributing to blood coagulation and / or granulation after implantation.

33. The vascular occluder of any one of claims 28-32, wherein the first and second membranes are configured to adsorb blood-clotting proteins, such as fibrinogen and albumin.

34. The vascular occluder of any one of claims 28-33, wherein the first and second membranes are configured to promote adhesion, activation, and aggregation of platelets.

35. The vascular occluder of any one of claims 28-34, wherein the first and second membranes are each configured as a fluid-permeable three-dimensional network structure.

36. The vascular occluder of any one of claims 28-35, wherein the first and second membranes each comprise a porous fluid-permeable random or aligned, three-dimensional network of polymeric microfibers and / or nanofibers.

37. The vascular occluder of claim 36, wherein the three-dimensional network of polymeric microfibers and / or nanofibers is configured with average fiber diameter smaller than about 5 micrometer, optionally smaller than about 2 micrometer, and / or average poresize smaller than about 50 micrometer and / or within a range of about 1 micrometer to about 50 micrometer.

38. The vascular occluder of claim 37, wherein the average fiber diameter is smaller than about 2 micrometers and the average pore size is within a range of about 1 micrometer to about 50 micrometers.

39. The vascular occluder of any one of claims 26-35, wherein the first and second membranes are formed by electrospinning.

40. The vascular occluder of claim 39, wherein the average fiber diameter is smaller than about 2 micrometers and the average pore size is within a range of about 1 micrometer to about 50 micrometers.

41. The vascular occluder of any one of claims 28-40, wherein the first membrane and the second membrane are configured to allow blood to flow therethrough during a predetermined blood-filling period and then to substantially prevent blood from flowing therethrough.

42. The vascular occluder of claim 41 , wherein the predetermined blood-filling period is smaller than 90 seconds.

43. The vascular occluder of claim 42, wherein the predetermined blood-filling period is smaller than 60 seconds.

44. The vascular occluder of claim 41 , wherein the predetermined blood-filling period is smaller than a minimally achievable result in a local activated clotting time (ACT) type test of coagulation.

45. The vascular occluder of any one of claims 28-44, wherein the first occluder portion and the second occluder portion are coupled to one another.

46. The vascular occluder of any one of claims 28-44, wherein the first occluder portion and the second occluder portion are not coupled to one another.

47. The vascular occluder of any one of claims 28-46, wherein the first occluder portion and the second occluder portion are configured to self-expand when released from a delivery lumen.

48. The vascular occluder of any one of claims 28-47, wherein the first and second occluder portions each comprise an expandable frame structure to which the first and second membranes are coupled.

49. A method for occluding a blood vessel, the method comprising: positioning a vascular occluder according to any one of claims 28-48 in a blood vessel; radially expanding the first and second occluding portions of the vascular occluder such that each engages a wall of the blood vessel; allowing blood to flow through at least the first membrane to a segment of the blood vessel between the first and second occluding portions until at least the first membrane is at least 75% clogged with blood cells and / or coagulated so as to retain a volume of blood in the segment of the blood vessel; and retaining the volume of blood in the segment of the blood vessel during coagulation and / or granulation thereof into a single coagulated or granulated mass sized to fill most or all of the segment of the blood vessel.

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