Fibered micro vaso-occlusive devices

Abstract: This is a micro-vaso-occlusive device 100 intended generally for occlusion of small arteries located distally in the vasculature. The invention is made up of a binder portion 102, often radio-opaque, which is short in length in comparison to the length of the included thrombogenic fibers 104. The fibers 104 form the other portion of the device. The micro device may have multiple binder sections 128. The fibers 104 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 is short in length in comparison to the length of the included thrombogenic fibers. The fibers form the other portion of the device. The micro device may have multiple binder section. The fibers 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 tumor 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 fibers. 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. None of these devices are 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 fibers 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, fibers 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 fibers. 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 fibers 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 magnetic portions do not appear to act as clasps on the fiber. FR-A1-2 608 418 discloses a vaso-occlusive device in which a retainer, having a passageway passing through its center, has a plurality of longitudinal elements passing therethrough, the ends of some of which elements are provided with barbs for attaching the device to a vessel wall. None of the disclosed devices is similar to the inventive vaso-occlusive device. According to the present invention there is provided a vaso-occlusive device comprising: a) at least one helical retainer coil having opposing ends, a retainer axis between those ends, an axial length and a passageway extending along said axis; b) a clip 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, and c) a multiplicity of fibres within the closed end of the clip having a maximum fibre length, wherein the ratio of the maximum fibre length: the retainer axial length is at least two. An embodiment of device in accordance with the present invention will now be described, by way of example only, with reference to the accompanying drawings. Figures 1-5 and 7-13 illustrate variations of device which are not in accordance with the invention claimed, but which nevertheless aid understanding of the embodiment of inventive device illustrated in Figure 6. The drawings are described below. Figure 1 is a side view of a generalised version of vaso-occlusive device showing the conventions used in describing various aspects of the invention. Figure 2 shows a side cutaway view of a vaso-occlusive device not in accordance with the present invention and having a generally spherical binder. Figure 3 shows a side cutaway view of a vaso-occlusive device not in accordance with the present invention and having a generally cylindrical binder. Figure 4 shows a side cutaway view of a vaso-occlusive device not in accordance with the present invention and having a coil as a binder. Figure 5 shows a side cutaway view of a vaso-occlusive device not in accordance with the present invention and which employs a coil retainer in which the fibres emanate from the side of the retainer. Figure 6 shows a cutaway side view of a vaso-occlusive device in accordance with the present invention and using a coil retainer and an interior clip to retain the thrombogenic fibers. Figure 7A shows a side view cutaway of a vaso-occlusive device not in accordance with the present ivention and having a ovoid binder and having passageways for the fiber 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 9A is a side view of a vaso-occlusive device not in accordance with the present invention and having multiple passageways through the binder and loops of the fibers through these passageways. Figure 9B is an end cutaway view of the Figure 9A device. Figure 10 is a side cutaway view of a multiple binder vaso-occlusive device not in accordance with the present invention and in which the fibers extend radially in the region between the binders. Figure 11 is a side cutaway view of a multiple binder vaso-occlusive device not in accordance with the present invention. Figure 12 show a side cutaway view of a multiple mixed binder device with folded fibers encompassing an end binder. The invention is a vaso-occlusive device typically made up of two components (which may be used in multiples): a retainer coil and a multiplicity of thrombogenic fibers, often in the form of a bundle. The retainer may also include a clip for fibers. Figure 1 shows in cross section a side view of a generalization of a non-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 it retains the included fiber 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). Most desirable 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. The fiber portion (104) of the device (100) is a multiplicity of fibers having a length (114) which reflects the longest fiber extension in a specific device (100). Preferable are those structures in which the ratio of the length (114) of the fibers 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 and 2.29 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, polesters such as the Nylons and polyethylene terephthalate (e.g., DACRON), polyurethane, polyethylene, etc. Figure 2 shows a side view, cross section of a non-inventive device (120) having a generally spherical retainer (122). 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) 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. 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 tip (135) to the coil. Tip (135) may be made in a variety of different ways. The typical way of making such tip when the coil is of material which easily melts is simply to melt a portion of coil (133) to form the rounded tip on (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 an inventive 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 device (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 then heated or an amount of epoxy 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 a non-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 variation (150) of the device shown in Figures 7A and 7B. The difference is the multiple number of passageways (144) in the retainer (146). Figures 9A and 9B show a variation of the device shown in Figures 8A and 8B. This device (154) uses the multiple passageway (144) retainer (146) portrayed in Figures 8A and 8B. Two bundles of fiber (156) are used. Each bundle (156) is routed through a first passageway (144) and looped around externally and then through an adjacent passageway. This variation gives a larger overall effective diameter to the device (154) with enhanced thrombogenic area. Figure 10 shows a longer variation (160) of a non-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. It also provides for enhanced thrombogenicity. Figure 11 shows a variation of a non-inventive vaso-occlusive device (166) in which multiple retainer (128) are used to hold the fiber bundle (168) in a straight through passage. In the variation shown in Figures 10 and 11 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 12 shows a multiple retainer (128) variation of the devices (170) 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 13 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). The fiber bundle (184) is also folded back over itself at the end (186) and passed back through one of the binders (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 U.S. Patent App. Ser. No. 07/978,320, filed October 9, 1992, to Zenzen et al.

Claims: A vaso-occlusive device (136) comprising: a) at least one helical retainer coil (139) having opposing ends, a retainer axis between those ends, an axial length and a passageway extending along said axis; 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, and c) a multiplicity of fibres (143) within the closed end of the clip (141) having a maximum fibre length, wherein the ratio of the maximum fibre length: the retainer axial length is at least two. The device of claim 1, wherein the clip (141) is held in place within the retainer coil (139) by a rounded end (137) at the end of the retainer coil opposite that adjacent the fibres (143). The device of either of claims 1 and 2, wherein the retainer coil (139) has a diameter and wherein the retainer has an axial length: diameter ratio of no more than two. The device of any one of the preceding claims, wherein the retainer coil (139) is radio-opaque. The device of any one of the preceding claims, wherein the retainer coil (139) comprises a material selected from the group consisting of stainless steel, gold, tungsten, platinum, palladium, rhodium, rhenium, and alloys thereof. The device of any one of claims 1 to 4, wherein the retainer coil (139) comprises a polymeric material. The device of claim 6, wherein the polymeric material comprises an epoxy.

Inventors: GIA SON M, SEPETKA IVAN, GIA, SON M., SEPETKA, IVAN
Applicants: BOSTON SCIENT LTD, BOSTON SCIENTIFIC LIMITED
Application year: 1996
Main classification: A61B17
IPC codes: A61F2, A61B19, A61B17