Neurocoil for use in endovascular treatment and mandrel for manufacturing same

Abstract

A complex coil for endovascular treatment, a mandrel for constructing the complex coil, and a method for constructing the complex coil are disclosed. The coil generally includes a primary wire that is formed into a primary spring and then formed into a secondary three-dimensional shape, which forms a secondary set of successive loop layers. A fixed number of loops define layers that form a locus of points that encircles a generally spherical surface and forms a repeatable pattern, with the second successive loop layer of the repeatable pattern generally being larger in diameter and spherical size than the previous layer. The locus of points from four or more loops defines an encapsulating spheroid suitable for filling emboli or creating frames, with the size and geometry of the successive loops being able to be manipulated by various unique design means of the mandrel.

Description

[Technical field]

[0001] The present invention relates generally to implantable devices for interventional therapy and vascular surgery, and more specifically to therapeutic devices in the form of embolic or vaso-occlusive coils that can be placed within a patient's vasculature, and mandrels for making novel coil structures. [Background technology]

[0002] In the treatment of vascular lesions and diseases, the field and science of interventional therapy and surgery through small incisions or access through vasculature or body orifices continues to advance in order to reduce trauma to the surrounding tissue at the treatment site. One important aspect of such therapy involves the use of catheters to place a therapeutic device at the treatment site with access through the vasculature. Examples of such procedures include percutaneous transluminal angioplasty, placement of stents to reinforce the vessel wall, and the use of vascular occlusion devices to treat lesions or weaknesses in the vasculature. Summary of the Invention [Problem to be solved by the invention]

[0003] One particular area of ​​interventional therapy that can take advantage of recent technological advances is the treatment of neurovascular lesions. As smaller and more sophisticated structures and materials are developed, these advances have made it more feasible to treat cerebrovascular lesions in humans that were previously inoperable or associated with unacceptable risks through traditional surgery. One type of therapy that has been favored in the treatment of neurovascular lesions is the placement of vascular occlusion devices, such as embolic coils, by catheter into damaged segments of veins or arteries.

[0004] Vaso-occlusive devices are therapeutic devices that create embolisms to block or restrict the flow of blood through a blood vessel or to prevent blood from entering an aneurysm in a blood vessel. One such vaso-occlusive device that is widely used for this purpose is a helical wire coil that deforms into a three-dimensional shape in the deployed configuration to engage the wall of the aneurysm. Vaso-occlusive devices are designed to conform to the shape of the aneurysm and are made of preformed strands of material, such as platinum-tungsten alloys. U.S. Patent Publication No. 2009 / 0297582, the contents of which are incorporated herein by reference, describes some examples of materials suitable for embolic coils. These vaso-occlusive devices comprise one or more vaso-occlusive strands that are wound to form a generally spherical or ovoid shape in the deployed state. The strands are usually first helically wound in a generally linear manner, then wound around an appropriately shaped mandrel, and then heat treated to assume the shape of the mandrel after removal of the mandrel. When so constructed, radiopacity is provided by the inherent radiopacity of the platinum alloy wire. The coils can be of various configurations and are generally characterized as "framing coils" or "filling coils." Framing coils are intended to have a stiffer, more rigid shape that approximates the size of the lesion (i.e., has the diameter of the aneurysm), while filling coils tend to be less stiff and function to occupy the space remaining in the void created by the previously placed framing coil. In a preferred embodiment of the invention, the unique mandrel defined herein can be used to make the framing coil and also the complementary filling coil with only minor changes in the technique used to wind the primary strands around the mandrel.

[0005] Delivery of such vaso-occlusive devices is accomplished by a variety of means, including inserting the coil device into the patient's vasculature via a catheter and placing it at the treatment location. The coil is releasably attached to a pusher element, and a variety of detachment mechanisms are available for detaching the device from the pusher.

[0006] As previously mentioned, aneurysm framing coils are intended to engage aneurysms that may be generally spheroidal in shape. Framing coils are formed by shaping the primary windings of the coil (typically 1 / 3-1 / 2 mm in diameter) into a three-dimensional pattern with an average diameter ranging from about 2 mm to 20 mm for some neurovascular applications. "Framing" refers to the technique of placing the first coil (and sometimes subsequent coils) within the aneurysm and allowing the coil to expand from a more linear helical configuration on the delivery catheter into a roughly spheroidal shape that conforms to the interior of the aneurysm. For this reason, framing coils are designed and specialized to treat aneurysms of a particular diameter. Thus, a 10 mm framing coil is designed to treat aneurysms that are shaped approximately like a 10 mm diameter sphere, with care being taken to ensure that the coil does not damage weakened tissue at the treatment site.

[0007] An important feature of embolic coils used for this purpose is that they deploy and unfold in a predictable and consistent manner as they assume their final configuration, allowing the physician to predict and control the delivery of the coil to the vulnerable aneurysm or vessel. It is advantageous for the coil to have as much surface area as possible in gentle contact with the surface of the aneurysm as it deploys and follows the contours of the aneurysm. When an aneurysm forms in a vessel, the opening in the vessel wall at the base of the aneurysm is called the neck. It is important that the coil placed in the aneurysm does not fall through the neck and into the parent vessel. The diameter and shape of the coil loops are designed to minimize the possibility of the coils slipping out and entering the parent vessel, which could result in a very serious risk of embolic stroke. For example, if the coil had a loop with a diameter smaller than the diameter of the neck of the aneurysm, the loops could have a very undesirable tendency to be placed outside the neck and into the parent vessel.

[0008] In addition to framing coils, another type of coil is commonly called a filling coil. Filling coils are generally deployed after one or more framing coils are in place, and the filling coils are designed to be softer (more flexible) and fill the voids of the deployed (harder) framing coils. It is well known in the art that aneurysms with more dense coil packing tend to heal more efficiently, and thus devices with higher "packing density" are desirable. Therefore, it is beneficial to have a filling coil that can easily occupy the remaining space between the deployed coils in the aneurysm to obtain the highest possible packing density. [Means for solving the problem]

[0009] Briefly and generally, the present invention is a therapeutic device for detachment and deployment within a patient's vasculature that possesses several unique features not found in the prior art.

[0010] Treatment coils are typically formed by winding a preformed linear helical wire spring (called the primary winding) around a form or mandrel and then heating the mandrel and spring to cause the spring to assume the shape of the mandrel (called the secondary shape). Prior art framing coils typically use a mandrel with a generally rounded cylindrical post protruding from a central hub around which the primary winding is wound in a particular pattern.

[0011] It is quite common that the desired length of the embolic coil exceeds the length required to encircle all the posts of the mandrel as the windings are wound sequentially around each post. Thus, to complete the shaping of the coil, the winding of the wire continues on the cylindrical post with the next loop stacked on top of the loop already encircling the post. With a cylindrical post, the next series of loops of the coil will have the same diameter as the previously formed loop on the same post. As the spherical volume of the aneurysm is filled with coils, the remaining volume of the aneurysm is reduced by the increase in the volume of the previously placed coil, reducing the available space within the aneurysm. It is a common procedure for the treating physician to select a coil with a smaller diameter to fit within the previously placed coil in order to reduce the outward forces on the aneurysm wall and reduce the risk of rupture (called "nesting"). With a cylindrical post, successive coils of the same diameter may compete for the same space within the aneurysm and may not nest, which may reduce the final packing density that can be achieved and increase the outward forces on the aneurysm.

[0012] A feature of the invention is a mandrel with a coil-forming post shaped into a cone or frusto-cone, where the diameter of each successive loop wound around the post is slightly larger than the loop already formed on the post. When more than one complete layer of loops defines the coil and successive loops are formed on the post, the coil so formed is loaded onto a pusher mechanism for deployment in the opposite direction from the direction in which it was formed. In this case, for a single embolic coil, each successive loop of the coil forming a layer that is deployed later will have a slightly smaller diameter than the previous successive loops. This is advantageous because the aneurysm being treated fills from the outside in, and the later deployed loops (which have smaller diameters and decreasing spherical radius) will fit and fill more easily within the larger loops already deployed, with the volume available for the successive loops decreasing. The slightly smaller subsequent loops will also reduce the outward forces on the fragile aneurysm, which may reduce the rupture rate during the procedure. With conventional cylindrically shaped posts, each successive loop has the same diameter as the previous loop and competes with the previously deployed loop for the same size deployment, which can undesirably increase the outward force on the aneurysm wall.

[0013] Many prior art framing coil mandrels have four or six cylindrical posts extending radially from a central sphere. In the six-post configuration, each loop of the coil is tighter curved and has a smaller diameter than in the four-post configuration because a given surface area of ​​a given sphere is divided among six posts instead of four. For a given primary winding, forming these smaller radius loops in the secondary shape makes the coil stiffer than a coil with a larger radius loop. Thus, on this basis, the four-post mandrel configuration has an advantage over the six-post configuration. However, in the four-post case, the larger diameter posts and resulting loops leave a larger surface area between adjacent posts, resulting in more unwanted untreated portions of the aneurysm compared to the space remaining between the six posts. Thus, it is clear that neither the four-post nor the six-post configurations are ideal. One prior art coil (U.S. Pat. No. 7,879,064) describes a means of filling these voids between the posts of a four-post mandrel with a coil having smaller loops formed in these apex voids. These additional loops would have to be much smaller in diameter, certainly introducing an embolic risk (related to falling out of the neck) and adding very stiff sections to the embolic coil upon deployment (compared to the larger loops in the primary configuration), both of which are undesirable characteristics of an embolic coil. One aspect of the present invention solves the problem of the larger untreated intra-apical space of the 4-post mandrel while taking advantage of the benefits of the 4-post mandrel, without introducing additional embolic risk or stiffening of the coil.

[0014] In one embodiment of the present invention, a mandrel is provided that uses four posts instead of six cylindrical posts, thus providing the advantage of a larger diameter for each loop. However, this mandrel is formed with posts shaped in a rounded triangular, i.e., triangular elliptical, profile rather than circular. A circular post geometry results in a larger curvilinear space on the base sphere (corresponding to the untreated aneurysm dome) between each adjacent post. Changing the post geometry from circular to triangular (as in the case of a four-post mandrel) results in the rounded tips at the apexes of the triangles better filling the untreated space and providing a larger coverage of the aneurysm surface area. Another advantage of the "triangular" or non-circular loops formed by such shaped mandrel posts is that loops formed on non-circular posts are generally softer and more malleable than circular loops. With a non-circular configuration, the generally linear sections of the loops have a nearly infinite radius, resulting in even greater malleability. This may seem counterintuitive, but as previously discussed, coils with smaller radii (i.e., smaller loops) are stiffer than larger loops. The triangular posts provide three substantially straight segments in each loop that are extremely flexible (due to the nearly infinitely large radius or curvature) and can conform when placed within the aneurysm. This novel advantage of the non-circular posts in the present invention is applicable to any mandrel configuration, regardless of the number of posts or the geometric orientation of the posts in relation to one another. For example, when used with a six-post mandrel, each post is tangent to four adjacent posts, so that the posts are formed as rounded squares (or four-sided polygons).

[0015] Another advantage of the present invention is that when the primary coil is formed on the mandrel, each post is tangent to each of the remaining posts, and these remaining three posts are equidistant from one another around the post, so that each loop is formed by winding the primary wire exactly 360 degrees around the post and then 120 degrees to the next post (i.e., 1 1 / 3 turns around each post). The winding is wound 360 degrees around the post, and then at the point of another third turn, the winding is aligned tangent to the adjacent post and the winding is transferred to that adjacent post. The winding continues, with each post receiving 1 1 / 3 turns of wire. The winding pattern predictably reverses direction (clockwise to counterclockwise or vice versa) on the immediately preceding wrapped post, and proceeds in a similar, predictable manner, with each successive loop having the same predictable length (1 1 / 3 turns around each post). In the case of a four-post mandrel configuration, the resulting coil advances in a repeatable, consistent manner from one post to the next until the primary winding has completed exactly one-and-a-third revolutions around each of the four posts and returned to exactly the same starting point on the first post, and this pattern is repeated until the selected length of the coil is reached. Coils formed with such repeatable, and therefore predictable, completed loops advantageously yield framing coils that have a strong tendency to assume a spheroidal shape, and thus are adaptable to frame generally spherical aneurysms.

[0016] In another embodiment of the invention, winding may proceed as described above, but with successive partial loops, making a partial turn, specifically a 2 / 3 (240 degree) turn, around each post of the four-post mandrel and then transitioning tangentially to the next adjacent post. The partial loops are less robust in shape as formed as a complete coil, and the successive partial loops are more adaptable to conform to irregular shapes as are the corresponding complete loops. Coils formed with such repeatable partial turns, while also tending to assume a generally spheroidal shape, are considerably more flexible and therefore advantageously produce a filling coil adaptable to frame irregularly shaped aneurysms, such as multilocular or fusiform aneurysms, and also more adaptable as a subsequent filling coil in any aneurysm.

[0017] In another embodiment of the invention, a unique coil can be manufactured that acts as both a framing coil and a filling coil by first wrapping 240° loops around some number of the posts of a mandrel (creating a series of filling loops), and then forming an aneurysm frame by wrapping 480° around typically at least four subsequent posts to create a series of framing loops. For such combination coils, the framing portion of the coil is typically catheterized first, and the aneurysm is framed first with the robust full loops, which are then filled with the softer partial loops.

[0018] In the case of an embolic coil, the first and last loops are advantageously smaller in diameter than the other loops of the coil, and the tip of the first coil curls inward (away from the saccular aneurysm), thereby reducing the risk of aneurysm puncture. Another novel feature of the invention is that, in one embodiment, at least one of the posts at the base of the frustoconical mandrel is provided with a groove, so that the first loop wound within the groove has a smaller diameter than the other loops wound outside the groove. The groove is dimensioned such that as the first loop of the coil is wound within the groove, the depth and width of the groove are filled by the loop of the coil. Once the groove is completely filled by the first loop, any subsequent loops wound on this post simply ride on top of the first loop (usually corresponding to the diameter of the original post, since the previous loop has filled the groove) or are placed on the mandrel post and have a correspondingly larger diameter equal to the diameter of the post.

[0019] It is also desirable for the last loop of the embolic coil to be smaller in diameter than the other loops of the coil, so that the smaller radius of the last loop makes it a little stiffer and therefore more likely to be retracted away from the indwelling catheter and into the coil mass rather than partially protruding into the parent vessel. Another feature of the invention is an embodiment in which the last loop of the coil has a smaller diameter than the previous loops. This aspect of the invention is accomplished by providing a reduced diameter portion (or groove) on the upper side of the post through which the last loop is formed. This reduced diameter portion of the post provides a location on the post for the last loop to be formed into the groove, thus forming a loop that is smaller in diameter than the previous loops.

[0020] These and other advantages of the present invention will be best understood with reference to the accompanying drawings and the following detailed description of the invention. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a three-dimensional perspective view of a prior art embolic coil. [Figure 2A] 1 is a schematic diagram of a catheter for delivering an embolic coil of the present invention. [Figure 2B] FIG. 2B is a schematic diagram of the coil of FIG. 2A placed within an aneurysm. [Diagram 3] FIG. 1 is a side view of a first embodiment of a mandrel of the present invention. [Figure 4] FIG. 4 is a top axial view of the head of the mandrel of FIG. 3 showing the location of the posts. [Figure 5A] FIG. 1 is a cross-sectional view of a prior art cylindrical post having multiple windings thereon. [Figure 5B] FIG. 2 is a cross-sectional view of a first embodiment of a mandrel post of the present invention having multiple windings thereon. [Figure 6] FIG. 5 is a three-dimensional perspective view of a simple geometric representation of the orientation of the loops formed by wrapping around the mandrel posts of FIGS. 3 and 4. [Figure 7A] FIG. 11 is a side view of a second embodiment of the present invention. [Figure 7B] 7B is a cross-sectional view of the embodiment of FIG. 7A taken along line 7B-7B. [Figure 7C] FIG. 4 is an axial top view of the head of the mandrel of FIG. 3. [Figure 7D] FIG. 7B is an axial top view of the head of the mandrel of FIG. 7A. [Figure 8A] FIG. 2 is a cross-sectional view of another embodiment of a mandrel of the present invention. [Figure 8B] FIG. 8B is an enlarged cross-sectional view of the head of the mandrel of FIG. 8A. [Figure 8C] FIG. 8C is an enlarged cross-sectional view of the head of the mandrel of FIG. 8B with the wire wrapped around the post. [Figure 9A] FIG. 2 is a cross-sectional view of another embodiment of a mandrel of the present invention. [Figure 9B] FIG. 9B is an enlarged cross-sectional view of the head of the mandrel of FIG. 9A. [Figure 9C] FIG. 9C is an enlarged cross-sectional view of the head of the mandrel of FIG. 9B with the wire wrapped around the post. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Figure 1 illustrates a prior art embolic coil having loops formed by a six-post mandrel, thus forming a series of six loops each forming a cube-like structure with three pairs of parallel sides, with the center of each loop lying on the X, Y, and Z axes of a Cartesian coordinate system centered on the origin at the center of the cube. The coil of Figure 1 is more stiff than desired due to the small diameter of the loops, which may slip out of the aneurysm and into the parent vessel in which the aneurysm resides. The present invention is intended to improve upon the performance of the coil of Figure 1.

[0023] 2A and 2B show an example of embolic coil deployment using a coil delivery catheter 120 according to one embodiment. The catheter can be configured to hold and deliver an embolic coil to a designated target location or site for treatment. For example, a frame can be deployed within an aneurysm 130 extending from a main or parent vessel 132. With reference to FIG. 2A, the coil can be delivered to the site of the aneurysm 130 through the catheter 120 in a folded or compressed configuration 110a in an undeployed state. In typical use, the elongated coil is pushed through the catheter with a pusher until it exits the catheter and is deployed within the aneurysm 130 (FIG. 2B). The pusher can include a thin wire 118 (often referred to as a pusher wire) for pushing the elongated coil through the catheter. Once the coil exits the catheter, the coil transitions from the elongated configuration 110a to an expanded configuration 110b, expanding within the aneurysm to achieve full deployment. FIG. 2B shows the coil in a partially deployed state as it expands within the aneurysm; as the coil is pushed out of the catheter 120, it assumes a spheroid shape, which allows it to deploy, expand, and continue to fill the aneurysm.

[0024] After the splayed coil is separated from the pusher 118, the catheter and / or pusher are withdrawn from the parent vessel, leaving the splayed coil 110b within the aneurysm. The coil can be appropriately sized for the aneurysm being treated such that the size of the fully splayed frame exceeds the opening or neck 134 from the parent vessel 132 to the aneurysm. This ensures that the splayed coil is retained indefinitely within the aneurysm and there are no loose ends that extend out of the aneurysm. The splayed coil 110b can at least partially fill and stabilize the aneurysm being treated.

[0025] FIG. 3 shows a mandrel 200 for making the novel embolic coil. The mandrel 200 comprises a cylindrical body 202 (which functions as a handle during use) and a head 205 attached to the body 202. The head 205 of the mandrel 200 includes a tapered end section 210 on which is mounted a spherical base 215 centered on the longitudinal axis 220 of the cylindrical body 202. Extending radially from the spherical base 215 are three posts 225. Each post 225 in the first embodiment is frustoconical, increasing in diameter as the post extends away from the spherical hub 215. Similarly, the tapered end section 210 of the body 202 is formed as a frustoconical surface that is shaped in the same way as the other three posts 225. These four projections (posts 225 and tapered section 210) have a circular cross section centered on their respective longitudinal axes 235, 220 (see FIGS. 3 and 4) that pass through the center of the spherical base 215. The intersection 230 of the post with the spherical base forms a circle of the same diameter as the intersection 240 of the tapered end section 210 with the spherical base 215. The circles of intersection between the post and the spherical hub and between the spherical base and the tapered end section 210 are equidistant from the center of the spherical hub, and the longitudinal axes 235 and 220 form an angle of 120 degrees with each other when viewed axially relative to the handle 202 (FIG. 4) and a tetrahedral apex-center-apex angle of approximately 109.47 degrees when viewed longitudinally (FIG. 8A).

[0026] FIG 5A shows a cross-section of a cylindrical post 150 of a prior art mandrel and two loops 151 of a coil surrounding the post 150. As shown, the loop formed outward from the base has the same diameter A (and therefore circumference) as the inner loop. FIG 5B shows a cross-section of a frusto-conical post 160 of a mandrel of the present invention and two loops 161, 162 of a coil surrounding the post 160. Due to the tapered shape of the post 160, as shown, a loop formed over a previous loop will advantageously have a larger diameter B than a loop of diameter A already formed on the same post.

[0027] A schematic of the resulting coil formed (and then removed) around the mandrel is shown in Figure 6. To produce such a coil, the primary winding of wire 300 is wound starting at point 301, making 1 1 / 3 turns around a first frustoconical post (not shown) having axis 410a, then proceeding to an adjacent post (not shown) having axis 410b, and similarly making successive 1 1 / 3 turns around posts having axes 410b, 410c, and 410d, ending at point 302, resulting in a first layer of four loops of the coil of this embodiment. If the desired length of the embolic coil exceeds that required to encircle the first four posts, the next series of loops are formed outwardly on each successive post, over the existing loops, resulting in a larger diameter and circumference coaxial with the existing loops on the post, as shown in the partial cross-section of Figure 5B. The resulting embolic coil has larger diameter loops than the coil of Figure 1 for a given aneurysm diameter, and is more flexible and less likely to back out of the aneurysm neck, making it more stable within the aneurysm. Furthermore, due to the frustoconical shape of each of the four posts, each successively wrapped layer of loops has a larger diameter than the previously wrapped loop, allowing the smaller loops of the coil to better nest within the larger loops when deployed in the reverse manner from when wound on the mandrel as described above.

[0028] Regardless of the length of the coil, the defining size of the coil (the size of the aneurysm that it is intended to insert as a framing coil) is defined by the spherical diameter of the outer surface of the last series of loops made on the mandrel. Specifically, the defining radius is the distance from the center of the spherical base 215 of the mandrel to the outer surface of the last loop on the mandrel. This ensures that the spherical shape of the coil does not exceed the aneurysm diameter. Another advantage of the frustoconical post is that the taper aids in the placement of the primary winding during winding of the primary strand onto the post, such that the first loop is placed at the smallest diameter at the spherical base, or flush against the outer surface of the spherical base, or over a previously wound loop.

[0029] In another unique and independent advantage of the present invention, the protruding posts are not circular in cross section. With the advantageous four-post configuration, the loop diameter is larger than with a six-post mandrel of corresponding size. With fewer and larger loops, there is more surface area between adjacent loops. This can result in a larger area of ​​untreated aneurysm dome (without loop protection) in the region of the node between adjacent loops. FIG. 7A shows a mandrel 400 having posts 900 and base posts 901 that are not circular in cross section but are in the shape of rounded triangles. When configured in this manner, the mandrel posts 900, 901 (and the resulting coil loops) have a triangular cross section with straight portions and rounded apexes. FIG. 7B shows the resulting coil loops 910 that are encircled by these triangular posts 900 and 901, which have a longer and larger circumference than the loops with circular posts, and have straight portions 920 and non-straight portions 930. As explained, in the case of a four-post mandrel, the tips of each of the three adjacent triangular posts better fill the four untreated spaces created by the circular posts, thereby providing greater support to the aneurysm surface. FIG. 7c shows the untreated spaces 740 between the three adjacent posts of a four-post mandrel with circular posts, while FIG. 7D shows the smaller untreated spaces 750 between the three adjacent posts of a four-post mandrel with triangular posts with rounded apexes. Similarly, the longer the loops and the greater the surface area coverage, the higher the packing density of these unique coils will likely be (more coil volume placed within a given aneurysm volume). Furthermore, in the case of a six-post mandrel, the corresponding unrounded posts can also be configured as a square (four-sided polyhedron) configuration with rounded corners to fill the spaces between the four adjacent posts. Both of these unique features of the present invention are highly desirable in the field of neurovascular treatment of aneurysms.

[0030] It is known in the art that for a given wire (or primary wound coil) size, tighter (smaller) wound loops or coil diameters will be stiffer than larger diameter loops. This becomes most pronounced with coils shaped to secondary sizes for very small aneurysms (i.e., less than about 3 mm in diameter). Another unique, though less obvious, advantage of the non-circular post configuration of the present invention shown in FIG. 7 is that the coil loops so formed have less stiff areas along the generally straight sections 920 of the coil loop, resulting in a much more flexible coil configuration than would be the case with a conventional circular post.

[0031] FIG. 8A shows a further optional embodiment of a mandrel 500 of the present invention. FIG. 8A shows an axial cross section of a mandrel with a cylindrical body 502, a frustoconical post 525, and a frustoconical tapered end 535 similar in most respects to the previously described post. However, to create a smaller diameter loop, which is sometimes desirable, a groove 510 is formed at the intersection of the sphere 215 and the outer surface of the tapered end 535, so that the first wrapped loop 601 of the wire fills and occupies the groove 510 as the wire is wrapped around the post in the groove (FIG. 8C). Arrow A' reflects the reduced circumference of the loop when compared to a loop formed using the unfinished surface 545 of the post 535 along arrow A. The groove 510 can be used to create an initial smaller diameter first loop of the coil to orient the first deployed loop inwardly of the aneurysm, resulting in an advantageous coil with a smaller initial loop that protects the tissue within the aneurysm when the coil is first inserted into place. Alternatively, groove 510 can be used to create a coil with a smaller diameter final loop that is subsequently placed to obtain an advantageous coil, the resulting smaller diameter of the final loop having a greater tendency to be pulled back into the saccular aneurysm when the coil is detached from the pusher wire. As shown in Figures 8B and 8C, the diameter of loop 604, designated 801, is equal to the diameter of loop 602, designated 801, by wrapping the wire around surface 545 at the location most proximal to ball 215. The diameter 802 of the subsequent loop 603 is equal to the diameter of loop 605, also designated 802. The loop 601 occupying groove 510 has the smallest diameter 800.

[0032] 9 illustrates a further optional embodiment of a mandrel 600 of the present invention having a cylindrical body 602. As shown in FIG. 9A, one or more of the four posts 625 (and / or tapered end 635) have a reduced diameter section 655 at the periphery of the post at a specified distance H from the surface of the spherical base 610 (FIG. 9B). This reduced circumference area 655 can be used to create a reduced circumference loop(s) when the primary wire is wound. As previously mentioned, the reduced diameter area 655 of the post 625 can be used to create a loop of the coil to obtain either an initial smaller diameter first loop that protects the tissue within the aneurysm as the coil is inserted into place, or a smaller diameter final loop of the coil that is advantageous for helping the final loop to be pulled into the aneurysm upon disengagement depending on the direction in which the resulting coil is introduced into the aneurysm. When combined with the advantageous groove 510 on the first post (defined above), the reduced diameter area of ​​groove 510 combined with the aspect of the post at 655 allows for the creation of smaller coils in both the first and last loops. It should be appreciated that the benefits of reduced diameter in the outer area of ​​the post can also be achieved through the use of a groove appropriately relocated to the outside of the post.

[0033] Additionally, if the frustoconical taper of the post is not sufficient to obtain the desired full reduction in circumference compared to loops formed on the bare surface of the post, then the reduced circumference portion of the post can be used to form a series of loops of reduced diameter. As shown in FIG. 9C, loops 670 and 676 have a common loop diameter indicated by arrow A, while subsequent loops 671 and 679 have slightly larger loop diameters due to the frustoconical post shape. However, loop 682 occupying reduced area 655 has a smaller loop diameter corresponding to arrow A'' due to the varying width of post 625 at the distal region. Loop 682 can be made as small as necessary by forming recesses 655 in the post, resulting in a coil with the advantages described above. These described advantages of smaller loops formed by the protruding post grooves 510 and / or reduced diameter portions 655 are not specific to a four-post mandrel design, but can be applied to any mandrel with any number of posts and any post cross-sectional geometry. Additionally, the reduced diameter section may have a different cross-sectional geometry than the parent post. It will be appreciated that the groove and reduced diameter section may be used in combination to create smaller coils in both the first and last loops.

[0034] In another embodied advantage of the present invention, the base diameters of the posts are not abutting but are slightly spaced apart so that as the primary winding is wound around the posts, it lies flat against the base of the base sphere, leaving room for the next loop in successive loops around adjacent posts. That is, the posts are offset from one another (by reducing the diameter) by approximately twice the diameter of the coil spring that defines the primary winding. This feature reduces undesirable "bump" of the coil as it transitions from one post to the next, since the primary winding of the coil does not have to cross a previously formed loop of the coil as it transitions to the next adjacent post.

[0035] For completeness, various aspects of the invention are described below in a series of numbered appendices, the subject matter of which constitute examples and embodiments of the coils, mandrels, and methods disclosed throughout this application.

[0036] In the appended claims, a "coil" is understood as a three-dimensional structure resulting from winding a primary winding of wire, e.g. a primary spring, to form a number of loops, e.g. four main loops. Winding a primary spring to form a three-dimensional structure is sometimes called a secondary winding.

[0037] Each of the four main loops of the coil may define a respective plane, and the intersection of the four planes may form a generally tetrahedral shape. The loops of the coil, for example the four main loops, may be arranged in at least one "layer", where the layer has the shape of a three-dimensional structure. Thus, when a coil comprises four main loops, the layer formed by the four main loops has a tetrahedral shape.

[0038] Additional loops may be formed on and / or within the first layer of loops.

[0039] Embodiments of the present invention include: (1) an embolic coil for endovascular treatment comprising a primary wire formed into a helical coil spanning a generally spheroidal cage, the spheroidal cage being formed by layers of loops formed on protruding posts, the loops in each layer having a perimeter, and at least some of the loops of a subsequent layer formed on the protruding posts having a greater perimeter when compared to the loops of a previous layer on their respective posts.

[0040] (2) The embodiment described in claim 1, wherein the loop is generally circular.

[0041] (3) The embodiment described in claim 1, wherein the loop is non-circular.

[0042] (4) The embodiment described in any one of appendix (1) and (3) above, wherein the loop is substantially triangular.

[0043] (5) The embodiment described in any one of appendix (1) to (4) above, wherein the direction of rotation of the primary wire forming the loops alternates for adjacent loops in successive layers.

[0044] (6) The embodiment described in any one of appendices (1) to (5) above, wherein an outermost loop of at least one layer has a circumference that is smaller than the circumference of an adjacent loop.

[0045] (7) The embodiment described in any one of Supplementary Notes (1) to (6), wherein each layer includes a loop made up of a linear segment and a nonlinear segment.

[0046] (8) An embolic coil for endovascular treatment comprising a primary wire formed into a helical coil spanning a generally spheroidal cage, the spheroidal cage being formed by a series of loops forming at least one layer of loops, the loops in each of the at least one layer having a perimeter, at least some of the loops having a non-circular perimeter.

[0047] (9) The embodiment of claim 8, wherein at least some of the loops in the formed subsequent layer have a greater perimeter than the loops in the previous layer.

[0048] (10) The embodiment of any one of claims 8 and 9, wherein at least some of the loops are substantially triangular.

[0049] (11) The embodiment of any one of claims 8, 9, and 10, wherein some of the loops are composed of linear segments connected by nonlinear segments.

[0050] (12) A mandrel for forming an embolic coil comprising a spherical base and a plurality of posts extending radially from the spherical base, each post tapering along its longitudinal axis and increasing in width as it extends distally from the spheroidal base.

[0051] (13) The mandrel of claim 12, further comprising a groove about at least one post adjacent an intersection with the spheroid base to provide a reduced diameter region in the radially outwardly extending post.

[0052] (14) The mandrel of any one of claims 12 and 13, wherein the longitudinal axis of each post is oriented at an angle of 120 degrees to the longitudinal axis of each other post.

[0053] (15) The mandrel of any one of Appendices 12 to 14, wherein the post has a non-circular cross-section.

[0054] (16) The mandrel described in Appendices 12 to 15, wherein the posts are triangular.

[0055] (17) The mandrel of any one of claims 12 to 16, wherein a cross section of the post includes a plurality of linear segments and a plurality of nonlinear segments.

[0056] (18) The mandrel of any one of claims 12 to 17, wherein at least one post includes a reduced circumferential portion at a distal end of the post.

[0057] (19) The mandrel of any one of claims 12 to 18, wherein the posts are positioned such that all of the posts are equidistant from one another.

[0058] (20) The mandrel of any one of claims 12 to 19, further comprising a groove disposed at an intersection of the base and an outer surface of the at least one post.

[0059] (21) The mandrel of any one of claims 12 to 20, wherein at least one post has at least two grooves circumferentially disposed about the post.

[0060] (22) A mandrel as described in Appendices 12 to 21, wherein the cross section of the post is a rounded triangle, i.e., the cross section is a triangular ellipse.

[0061] (23) The mandrel of any one of claims 12 to 22, having more than four posts.

[0062] (24) A method of making an embolic coil for endovascular treatment, comprising the steps of providing a mandrel according to any one of claims 12 to 23 for forming an embolic coil, and forming a three-dimensional shaped coil having a plurality of loops by winding a primary wire formed into a helical coil spanning a generally spheroidal cage formed of a plurality of layers of loops, the loops being formed on radially protruding posts of the mandrel, at least some of the loops having a greater circumference when compared to the loops of an adjacent layer.

[0063] (25) The method of claim 24, wherein the winding of the primary wire around the radially protruding posts alternates with the loops in a common layer and with a rotational direction.

[0064] (26) The method according to claims 24 and 25, wherein the embolic coil includes a framing coil and a filling coil.

[0065] (27) The method of any one of claims 24 to 26, wherein the primary wire is first wound within a groove in one of the radially protruding posts, resulting in a loop having a smaller circumference compared to other loops of the embolic coil.

[0066] (28) The method of any one of claims 24 to 27, wherein the primary wire is wound around a reduced diameter portion of the post that protrudes radially at the distal end of the post, resulting in a loop of smaller circumference compared to the previous loop.

[0067] While specific embodiments, variations, and advantages of the present invention have been described and illustrated, it should be understood that the present invention is not limited to only these descriptions and illustrations. Those skilled in the art will readily recognize numerous substitutions, modifications, and variations of the above-described embodiments, and the scope of the present invention is intended to include all such substitutions, modifications, and variations.

Claims

1. 1. An embolic coil for endovascular therapy, comprising: a primary wire formed into a helical coil spanning a generally spheroidal cage, said spheroidal cage being formed by layers of loops formed on protruding posts; The loops in each layer have a perimeter, at least some of the loops of a subsequent layer formed on the protruding post have a greater perimeter when compared to the loops of a previous layer on the respective post; Embolization coils.

2. The embolic coil of claim 1 , wherein the loop is generally circular.

3. The embolic coil of claim 1 , wherein the loop is non-circular.

4. The embolic coil of claim 3 , wherein the loop is substantially triangular.

5. The embolic coil of claim 1 , wherein the direction of rotation of the primary wire forming the loops alternates for adjacent loops in successive layers.

6. The embolic coil of claim 1 , wherein an outermost loop of at least one layer has a circumference that is less than a circumference of an adjacent loop.

7. The embolic coil of claim 1 , wherein each layer includes loops made up of linear segments connected by non-linear segments.

8. 1. An embolic coil for endovascular therapy, comprising: a primary wire formed into a helical coil spanning a generally spheroidal cage, said spheroidal cage being formed by a series of loops forming at least one layer of loops; Each loop in the at least one layer has a perimeter; At least some of the loops have a non-circular perimeter. Embolization coils.

9. The embolic coil of claim 8 , wherein at least some of the loops in a subsequent layer formed on the protruding post have a greater perimeter than the loops in a previous layer.

10. The embolic coil of claim 8 , wherein at least some of the loops are substantially triangular.

11. The embolic coil of claim 8 , wherein at least some of the loops are made up of linear segments connected by non-linear segments.

12. 1. A mandrel for forming an embolic coil, comprising: A spheroid base; a plurality of posts extending radially from the spheroidal base; each post tapers along its longitudinal axis and increases in width as it extends distally from the spheroid base; Mandrel.

13. The mandrel of claim 12 further comprising a groove about at least one post adjacent an intersection with the spheroidal base to provide a region of reduced diameter in the radially outwardly extending post.

14. 13. The mandrel of claim 12, wherein the longitudinal axis of each post is oriented at an angle of 120 degrees to the longitudinal axis of every other post.

15. The mandrel of claim 12 , wherein the post has a non-circular cross-section.

16. The mandrel of claim 15 , wherein the cross section of the post is triangular.

17. The mandrel of claim 15 , wherein the cross section of the post includes a plurality of linear segments and a plurality of non-linear segments.

18. The mandrel of claim 12 , wherein at least one post includes a reduced circumferential portion at a distal end of the post.

19. 1. A mandrel for forming an embolic coil, comprising: A spheroid base; a plurality of posts extending radially from the spheroidal base; and wherein at least one radially extending post has a non-circular cross-section. Mandrel.

20. 20. The mandrel of claim 19, wherein at least one of the posts extending radially from the spheroidal base tapers along its longitudinal axis and increases in width as it extends distally from the spheroidal base.

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