Soft-ended fibred micro vaso-occlusive device

Abstract: This is a micro-vaso-occlusive device intended generally for occlusion of small arteries located distally in the vasculature. The device is made up of a binder, often radio-opaque, which may be short in length by comparison to the length of the included thrombogenic fibres. The fibres form the other portion of the device. At least one end of the device includes a solid but comparatively soft end typically made of a molten mass of the fibres. The micro device may have multiple binder sections. The fibres may be straight, looped, or tufted.

Description: This invention is a surgical device. In particular, it is a micro-vaso-occlusive device intended generally for occlusion of small arteries located distally in the vasculature. The invention is made up of a binder, often radio-opaque, which may be short in length by comparison to the length of the included thrombogenic fibres. The fibres form the other portion of the device. At least one end of the device includes a solid but comparatively soft end typically made of a molten mass of the fibres. The micro device may have multiple binder sections. The fibres may be straight, looped, or tufted. The use of occlusive devices in the vascular system and in other systems of the body, e.g., genito-urinary and biliary systems, is known.. In the vasculature, a physician may apply a vaso-occlusive device using endovascular techniques to a selected site to cause the site to fill with thrombus. The occlusion often changes in composition to a more collagenous composition over time. A variety of maladies may be treated in this way. For instance, an occlusion may be used to limit bleeding due to vascular accidents such as strokes or to fill abnormal vascular cavities such as aneurysm or to limit the flow of blood to an anomalous anatomical region, e.g., a tumour or one of the extraneous sites in a multi-focal electrical arrhythmia. Occlusive devices and materials used in such service are typically of two types: solids and reactive fluids. The class of solid-occlusive devices includes an eclectic variety of materials: hog hair, polyvinyl alcohol beads, collagen beads, latex beads, and silk or rayon fibres. Devices such as coils or balloons are also known and used. Cyanoacrylate glues are occasionally applied as vaso-occluding materials. These are not type-approved and a specific approval must be determined for each use. Glues are difficult to place within the vasculature and although they create excellent occlusions, they may do so at a site downstream of the desired site. The most practical of these devices and methods from both a precision placement aspect and an effectiveness aspect are vaso-occlusive coils with or without added thrombogenic fibers. An early endovascular coil device is found in Ritchart, et al., U.S. Patent No. 4,994,069. These devices are lengthy in comparison to the inventive devices described here and rely on the volume of the coil and the secondary shape of the coil after it exits the delivery catheter for defining the bulk of the resulting occlusion. A variation of the vaso-occlusive coils are shown in U.S. Patent Nos. 5,226, 911 and 5,304,194 to Chee et. al. Those patents show the use of longer vaso-occlusive coils having attached fibrous elements which are looped from place-to-place along the coils. A further variation is shown in U.S. Patent No. 5,382,259, to Phelps et. al. Phelps et al. shows a coil having a braided fibrous covering on the exterior of the coil. The braid is placed on the coil for the purpose of increasing the assembly's tendency to produce thrombus. Target Therapeutics, Inc. owns other patents relating to vaso-occlusive devices including "FIBERED MICRO VASO-OCCLUSIVE DEVICES" by Sepetka et al, EP-A-0 778 006 - Article 54(3) EPC - and "STRETCH RESISTANT VASO-OCCLUSIVE COILS" by Gia et al, EP-A-0 754 435, . Neither describes the devices claimed herein. None of these devices are soft-ended, vaso-occlusive devices having short binders holding significantly longer fibers. Other occluding devices having a plug-like form are known. U.S. Patent No. 5,095,917, to Vancaille, shows a transuterine technique for sterilization of females using a biodegradable plug. The plug is used in conjunction with the destruction of a mucous layer to form a site for inflammation and, upon healing, form an occlusion. No fibres are used in conjunction with the plug. U.S. Patent No. 5,192,301, to Kamiya et al., shows a closing plug which is to be delivered percutaneously to close somatic wall defects such as arterial septal defects (ASD). The plug is preferably of a shape memory polymer and has shape involving a cone at one end and a flange at the other. Again, fibres are not involved in the structure of the device. U.S. Patent No. 5,443, 478, to Purdy, shows a multi-element vascular device having an anchoring element and a lead element connected by fibres. The anchoring element is typically a coil forming a circular element. After deployment of the device from a delivery catheter, the anchoring element secondary shape is approximately the size of the vessel to be occluded. The typically somewhat smaller lead element is also often a coil but is depicted to be of a smaller size than the anchoring element. The fibres are not aligned with the coil upon deployment of the device, however. Japanese Kokai 4-312454 shows an occlusive device which appears to have multiple magnetic portions. The magnetic portions are shown to be square in Figure 1 and spherical in Figure 3 of the publication. The magnet portions do not appear to act as clasps on the fibre. None of the disclosed devices are similar to the inventive vaso-occlusive device. This invention provides a vaso-occlusive device as defined in independent claims 1 and 13. Preferred embodiments of the device are defined in dependent claims 2 to 12 and 14 to 16. The retainer may be radio-opaque. The fibres may be straight, looped, or tufted. The primary use of the device is in the very small vessels at the distal portion of the vasculature. The invention will be further described by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a side view of a generalized version of the inventive vaso-occlusive device showing the conventions used in describing various aspects of the invention. Figure 2 shows a side cutaway view of a variation of the invention having a generally spherical binder. Figure 3 shows a side cutaway view of a variation of the invention having a generally cylindrical binder. Figure 4 shows a side cutaway view of a variation of the invention having a coil as a binder. Figure 5 shows a cutaway side view of a variation employing a coil retainer in which the fibres emanate from the side of the Retainer. Figure 6 shows a cutaway side view of a variation using a coil retainer and an interior clip to retain the thrombogenic fibres. Figure 7A shows a side view cutaway of a variation of the invention having & ovoid binder and having passageways for the fibre element through the binder. Figure 7B is an end cutaway view of the Figure 7A device. Figure 8A is a side view of a device such as Figure 7A but having multiple passageways. Figure 8B is an end view of the Figure 8A device. Figure 9 is a side view, partial cutaway of a variation of the invention having fibres on the exterior of the coil component. Figure 10 is a side view, partial cutaway of a variation of the invention having braided fibres on the exterior of the coil component. Figure 11 is a side cutaway view of a multiple binder inventive device in which the fibres extend radially in the region between the binders. Figures 12, 13, and 14 show a side cutaway view of a multiple binder inventive device. The invention is a soft-tipped vaso-occlusive device typically made up of a number of components (which may be used in multiples): a retainer and a multiplicity of thrombogenic fibres, often in the form of a bundle, and a soft tip on at least one end of the retainer. The retainer may also include a clip to hold the fibres. Figure 1 shows in cross section a side view of a generalization of the inventive vaso-occlusive device (100). Figure 1 shows the convention and defines many of the specific terms used herein. The retainer or binder (102) is so-called because in most variations of the inventions it retains the included fibre bundle (104) located in the passageway (106) located in retainer (102). The retainer (102) has a retainer length (108) which extends along the retainer axis (110) between the furthermost ends of the retainer (102). Similarly, the retainer (102) has a diameter (112) which is the outer limit of the retainer (102) generally perpendicular to the axis (110). Desirable in this invention are retainers (102) in which the ratio of retainer length (108) to diameter (112) is no more than about two, preferably no more than about one. On at least one end of the retainer is a soft tip (121) which adheres to the retainer (102). The soft tip (121) may be formed by application of heat to the fibre bundles and melting the fibres in the fibre bundle (104) to form a shaped tip. Of course, the tip may be formed by application of other materials (settable glues or caulks such as epoxies) or by melting another polymeric composition onto the tip region. By "soft tip", we mean that the hardness of the tip as measured by accepted procedures (durometers, needle penetration, etc.) is less than the hardness of the helically wound coil itself. The fibre portion (104) of the device (100) is a multiplicity of fibres having a length (114) which reflects the longest fibre extension in a specific device (100). Desirable to this invention are those structures in which the ratio of the length (114) of the fibers (104) and the soft tip (121) to the retainer length (108) is at least two, more preferably at least five. Although the size of the device (100) is dependent upon the specific use to which it is placed, for most endovascular uses, the diameter (112) of retainer (102) typically will be between 0,127 to 2,286 mm (0.005 and 0.090 inches). Smaller sizes are desirable because of the intent to use those devices in small, distal arteries. For that indication, a retainer outside diameter (112) of 0,127 to 0,381 mm (0.005 to 0.015 inches) is preferred. The length (114) of the fibers are typically in the range of 2,54 mm (0.100 inches) or more. The device (100) is typically radio-opaque. Either or both of the retainer (102) and the fibers (104) may be radio-opaque. The retainer (102) may be made of any material suitable for holding onto the fibers. Typical materials include those metal or alloys selected from the group consisting of various stainless steels, gold, tungsten, platinum, palladium, rhodium, rhenium and alloys thereof. Preferred is an alloy of platinum and tungsten. Other materials suitable for the retainer (102) include polymeric composition, e.g., adhesives and moldable caulks. Especially preferred are epoxies, urethane, and silicones. Highly desirable as adjuncts to these polymeric compositions are particulate radio-opaque fillers, e.g., powder tantalum, barium carbonate, bismuth oxide, barium sulfate, and the like. The materials used in the fibers (104) may be thrombogenic material but typically are silk, cotton, polyesters such as the Nylons and polyethylene terephthalate (e.g., DACRON), polyurethane, polyethylene, etc. Figure 2 shows a side view, cross section of the inventive device (120) having a generally spherical retainer (122) and a soft end (123). In this variation, the passageway is an opening placed through the center of the retainer (122). The fibers (124) are held in place by, e.g., crimping or squeezing the retainer or by introducing a glue into the interior of the retainer. The fibers (124) are merely placed as tufts in the retainer (122). Figure 3 shows a side view cutaway of the device (126) in which the retainer (124) is generally cylindrical in shape. As was the case with the Figure 2 variation, the fibers (124) pass through the center of the retainer (128). A soft end is found at (125). Figure 4 shows a side view cutaway of a variation of the device (130) utilizing a coil as the retainer (132). When using high ductility metals in the coil retainer (132), it is sometimes desirable to augment the retainer (132) with a glue or the like to hold the fibers (124) with greater certainty. A soft tip (127) is included on one end. Figure 5 shows a side view cutaway of a variation of the device (131) utilizing coil (133) as the retainer. In this variation of the device, the fibers (134) do not pass completely through the axis of the retainer coil (133). Instead they are pulled through and are held in place by the coil itself after insertion between turns of the coil. The length of the various fibers (134) are much longer than is the length of coil (133). Typical of the use of a coil such as this in which the leading edge of the coil is exposed to the lumen of a blood vessel is the use of a rounded soft tip (135). Soft tip (135) may be made in a variety of different ways. The typical way of making such a tip is to melt a polymeric material onto the coil to form the rounded tip (135). Although the diameter of tip (135) is shown to be relatively the same as that of coil (133), the rounded tip may have a diameter which is larger or smaller than coil (133). Figure 6 shows still another variation of the vaso-occlusive device (136) utilizing a coil retainer (139). However, in this instance, the coil (139) is used only as a portion of a retainer assembly. The device which directly encloses the fibers (143) is a clip (141). The vaso-occlusive (136) additionally has rounded tip (137) as did the device shown in Figure 5. This device might be assembled in the following manner: First, multiplicity of fibers (143) is included in an open U-shaped clip (141). The shank of the clip is then slid into the interior of coil (139) until the fibers fit snugly against the end of the coil opposite that portion where the head (137) is to be found. The end of the coil (139) is formed of molten fibers from the fiber bundle or of an amount of a settable or molten polymer or the like is applied to form a rounded end (137). The rounded end (137), the coil (139), and the clip (141), all cooperate to hold fibers (143) in place. Figure 7A shows a side view, cutaway version of the inventive vaso-occlusive device (138) in which the retainer (140) is ovoid and the fibers (142) are introduced into a pair of passageways passing through the periphery of the retainer (140). Figure 7B shows an end view of the Figure 7A device (138) and shows the passageways (144) in the retainer (140). Although these passageways (144) are shown to be crimped or squeezed to hold the fibers (142) in place, it is acceptable to glue them in the external passageways (144). Passageways (144) are generally parallel to the axis of the retainer. Figure 8A and 8B show a variation (150) of the device shown in Figures 7A an 7B. The difference is the multiple number of passageways (144) in the retainer (146). Figure 9 shows a variation (152) of the invention having generally isolated fibers (154) exterior to the coil component (156). The coil component (156) also contains an interior fiber bundle (158). A soft tip (153) made in any of the ways discussed herein is located at one end of the device (152). Figure 10 shows a further variation (151) of the inventive device which is similar to the Figure 9 variation. The significant difference is that the exterior of the coil component (156) is at least partially covered with a fibrous, typically polymeric, braid (157) in place of the exterior fibers (154) in Figure 9. Figure 11 shows a longer variation (160) of the inventive device having multiple retainers (128). The fibers (162) are sized and situated in such a way that a portion of the bundle terminates between a pair of retainers (128). This variation (160) has the benefits of potentially shielding the retainer (128) from the interior of the delivery catheters during that delivery. A soft tip (161) is included. It also provides for enhanced thrombogenicity. Figure 12 shows a variation of the inventive vaso-occlusive device (166) with a soft tip (161) in which multiple retainers (128) are used to hold the fiber bundle (168) in a straight through passage. In the variations shown in Figures 11 and 12 and in the other multiple retainer variations, and of the retainers, e.g., ovoid, spherical, coil, cylindrical, may be used and they may be mixed, as is discussed below. Figure 13 shows a multiple retainer (128) variation of the device (170) with soft tip (161) in which the outer fibers (172) in the bundle (174) extend outwardly past the outer diameter of the retainer (128). The center fibers in the bundle (174) are straight in this configuration. Figure 14 shows another multiple retainer configuration (180) of the device. The retainers are a mixture of cylinder (128) and a coil (132). In this variation, the outer fibers (182) of the bundle (184) extend outwardly between the binders (128, 132). This variation of the invention provides a large leading hydraulic surface to the device when introducing the device using fluid pressure delivery. This device may be delivered using typical pusher techniques and an endovascular catheter as described in the Ritchart et al. patent or using the hydraulic techniques described in EP-A-0 623 012.

Claims: A vaso-occlusive device (100) comprising: a) at least one retainer (102) having opposing ends, a retainer axis (110) extending between those ends, an axial length (108) at least one passageway (106) extending along said axis; b) a multiplicity of fibres (104) passing through at least a portion of said at least one passageway (106); and c) at least one soft tip (121) adherent to at least one of said retainer (102) opposing ends, the hardness of the soft tip being less than the hardness of the retainer. The device of claim 1, wherein a soft tip is adherent each of said retainer opposing ends. The device of claim 1 or 2, wherein the retainer comprises a material selected from the group consisting of stainless steel, gold, tungsten, platinum, palladium, rhodium, rhenium, and alloys thereof. The device of claim 1 or 2, wherein the retainer comprises a polymeric material. The device of claim 4, wherein the polymeric material comprises an epoxy. The device of any one of the preceding claims, wherein the retainer has a shape selected from spheroid, ovoid and cylindrical. The device of any one of the preceding claims, wherein the retainer comprises a coil. The device of any one of the preceding claims, comprising a multiplicity of retainers. The device of claim 8, wherein a portion of the fibres terminate between at least two of said multiplicity of retainers. The device of claim 8 or 9, wherein the multiplicity of fibres extend outwardly from the retainer axis between said at least two of said multiplicity of retainers. The device of any one of the preceding claims, wherein the retainer has an external region and wherein at least a portion of the exterior region is covered with a braided polymeric covering. The device of any one of claims 1 to 10, wherein the retainer has an external region and wherein at least a portion of the exterior region is covered with polymeric fibres. A vaso-occlusive device (136) comprising: a) at least one helical coil (139) having opposing ends, a retainer access between those ends, an axial length, a passageway extending along said access; b) a clip (141) having a closed end and arms extending from that closed end, wherein the arms are passed through the retainer passageway from one opposing end to the other, c) a multiplicity of fibres (143) retained within the closed end of the clip; and d) a soft tip (137) adherent to at least one of aid helical coil (139) opposing ends, the hardness of the soft tip being less than the hardness of the helical coil. The device of claim 13, wherein the clip is held in place within the retainer coil by the soft tip. The device of claim 13 or 14, wherein the retainer coil comprises of material selected from the group consisting of stainless steel, gold, tungsten, platinum, palladium, rhodium, rhenium and alloys thereof. The device of any one of the preceding claims, wherein the retainer is radio-opaque.

Inventors: DOAN HANH, DOAN HONG, GIA SON M, HO LIEM, NGUYEN KIM, DOAN, HANH, DOAN, HONG, GIA, SON M., HO, LIEM, NGUYEN, KIM
Applicants: BOSTON SCIENT LTD, BOSTON SCIENTIFIC LIMITED
Application year: 1997
Main classification: A61B17
IPC codes: A61B19, A61M25, A61B17