US8771341B2 - Protuberant aneurysm bridging device and method of use - Google Patents
Protuberant aneurysm bridging device and method of use Download PDFInfo
- Publication number
- US8771341B2 US8771341B2 US13/647,315 US201213647315A US8771341B2 US 8771341 B2 US8771341 B2 US 8771341B2 US 201213647315 A US201213647315 A US 201213647315A US 8771341 B2 US8771341 B2 US 8771341B2
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- aneurysm
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- bridging device
- bridging
- catheter
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- A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
- A61F2230/0063—Three-dimensional shapes
- A61F2230/0073—Quadric-shaped
- A61F2230/0076—Quadric-shaped ellipsoidal or ovoid
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2250/00—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
- A61F2250/0014—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis
- A61F2250/0037—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis differing in height or in length
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2250/00—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
- A61F2250/0014—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis
- A61F2250/0039—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis differing in diameter
Abstract
A bridging device for supporting occlusive masses within an aneurysm located at a vascular bifurcation.
Description
This application claims priority to U.S. Provisional Application 61/556,122 filed Nov. 4, 2011, the entire contents of which are hereby incorporated by reference.
The inventions described below relate to the field of treatments for wide-necked aneurysms.
Hemorrhagic stroke accounts for 20% of the annual stroke population. Hemorrhagic stroke often occurs due to rupture of an aneurysm, causing bleeding into the brain tissue and resultant infarction of brain tissue. This can cause immediate death, as well as several well-known neurological defects such as paralysis, loss of sight, hearing or balance. Even if aneurysms in the brain do not rupture, they can cause severe neurological symptoms. Aneurysms may be filled with occlusive material, such as embolic coils, flow modifiers, stents or embolic polymers (ethylene vinyl alcohol, cyanoacrylate, etc.), to prevent rupture and alleviate neurological symptoms. This treatment is promising for many aneurysm in the cerebral vasculature. However, the cerebral vasculature includes many branches and bifurcations where an inlet artery branches into two outlet arteries. Large necked aneurysms (greater than 4 mm, with dome to neck ratios of greater than two) often form at these bifurcations, and the location and openings of these aneurysms often make it difficult to keep occlusive material, once placed in the aneurysm, from falling out of the aneurysm and into the arteries, thus blocking the outlet arteries. This can lead to an embolic stroke, which is just as severe as the hemorrhagic stroke the therapy is intended to prevent.
The devices and methods described below provide for occlusion of a wide necked aneurysm near a vascular bifurcation or trifurcation and placement of an occlusive material in the aneurysm while maintaining or creating a patent flow path for blood to flow from the feeding vessel into both branches of the bifurcation. The device comprises a vessel conforming, protuberant aneurysm bridging device, and is delivered with a delivery system capable of being deployed in the vicinity of a cerebrovascular aneurysm and allow for patent arterial flow while holding embolic material at the neck or slightly herniating into the neck of the aneurysm. The geometry and mechanics of the protuberant aneurysm bridging device are configured to cause retention of the device within the vessel in which the device is placed and maintain patency of the vessels into which the device is placed. The device delivery system is configured to deliver the device, through a microcatheter, with a high degree of accuracy under visualization by fluoroscopy, ultrasound, MRI, or the like. The device delivery system allows for the manipulation and expansion of the protuberant section of the device to conform to the vasculature
The protuberant aneurysm bridging device is configured to be placed in a parent vessel, across an aneurysm. The aneurysm can be located within or near a bifurcation. Bifurcation anatomies include the distal end of the basilar artery as well as the location where the middle cerebral artery begins, among many other examples. The protuberant aneurysm bridging device can also be placed across an aneurysm that is not at a bifurcation but formed into the sidewall of a generally non-bifurcated vessel. The protuberant aneurysm bridging device is configured to be coarse enough to allow blood to pass through its open walls but tight enough to keep embolizing coils trapped within an aneurysm such that they cannot protrude out of the aneurysm into the parent vessel or vessels.
The protuberant aneurysm bridging device can comprise a cylindrical first end and a cylindrical second end. The central region of the device can comprise a protuberant, or generally hemispherical, configuration. The central region can comprise a greater open area than the cylindrical first end, the cylindrical second end, or both ends. In other embodiments, the device can be configured with a cylindrical first end having a hollow lumen and be closed at the other ends. The closed other ends can comprise openings between the mesh or strut elements that are larger in some areas than the central areas of the device.
The device can comprise a mesh. In other embodiments, the device can comprise an expanded metal structure formed by slitting or laser-cutting a tube to form struts, for example. The device's mesh or struts can extend slightly into the aneurysm to insure the embolic material is not covering branching arteries.
The distal region, which corresponds to the distal end of the device (distal referring to the region intended to be disposed deepest within the vasculature (farthest for the origin of an artery), which generally corresponds to the end of the device farthest from the delivery catheter or insertion point in the body) comprises two zigzag segments 24 and 25 disposed with opposing vertices 26 and 27 aligned (the two opposing zigzag segments form a diamond-cell segment 28, characterized by diamond shaped opening between defined by the struts of opposing V-shaped pairs of struts). The zigzag segments are superelastically or resiliently biased to open to the generally cylindrical configuration shown in order to expand to engage the walls artery in which it is place with sufficient compliance mismatch to fix the distal region within the artery.
The proximal region, which corresponds to the proximal end of the device (proximal referring to the region intended to be disposed closest to the origin of an artery, which generally corresponds to the end of the device closest to the delivery catheter or insertion point in the body) comprises a zigzag segment 29 and several V-shaped elements 30 disposed with tops 31 aligned with proximally pointing vertices 32 (forming spaced, non-contiguous diamond-cell segments 33, characterized by diamond-shaped opening defined by the struts of opposing V-shaped pairs of struts). The zigzag segments are superelastically or resiliently biased to open to the generally cylindrical configuration shown in order to expand to engage the walls of the artery in which it is placed with sufficient compliance mismatch to fix the proximal region within the artery. The distal region and proximal region establish a cylindrical structure with dimensions, in their expanded configurations, that match or slightly exceed the diameter of the blood vessel in which they are to be placed. Though V-shaped elements are preferred (for both the distal region and proximal region), the zigzag segments can be configured instead as sinusoidal or wavy segments, with U-shaped elements, for use in larger environments.
The central region 23 is intended to be bulbous, and protrude radially from the cylinder established by the distal end and proximal end, in its expanded configuration. The central region comprises a pair of opposing zigzag segments 34 and 35 with the vertices aligned to meet near the center of the device, again forming a diamond-cell segment 36 (that is, the centrally pointing vertices of the first central zigzag segment 34 are aligned with centrally pointing vertices of the second central zigzag segment 35). This paired zigzag or diamond cell segment is joined, on its proximal end, to the distal end of proximal region. The proximally pointing vertices 37 are connected to the distally pointing vertices 38 of zigzag segment 29 with spirally oriented strut segments 39 which run, along a helical or spiral course relative to the cylinder established by the distal and proximal regions, from the distally pointing vertices 38 to the proximally pointing vertices 37. Likewise, the paired zigzag or diamond cell segment 36 is joined, on its distal end, to the proximal end of distal region. The distally pointing vertices 40 are connected to the proximally pointing vertices 41 of zigzag segment 29 with spirally oriented strut segments 42 which run, along a helical or spiral course relative to the cylinder established by the distal and proximal regions, from the distally pointing vertices 40 to the proximally pointing vertices 41. The zigzag segments and spiral struts are superelastically or resiliently biased to open to the generally cylindrical configuration shown (larger diameter than the distal region and proximal region) in order to expand to engage both the walls of the artery in which it is placed and bridge the open neck of the aneurysm. The spirally oriented struts provide a hinged connection between the central region and both the proximal region and distal region. Because the central region is intended to bulge and protrude from the central axis of the device, it is preferably devoid of additional structures, beyond the spiral struts, zigzag segments and markers, so that it is not constricted from deforming during installation according to the procedure described below.
At the proximal end of the bridging device, the device is removably attached to the delivery wire 43 through an electrolytic detachment joint 44 and several tethers 45. The tethers are additional struts, formed integrally with the remainder of the device, extending around the cylindrical volume established by the proximal region segments, to join the detachment joint along the side of the device. The delivery wire runs through insertion catheter 2.
The bridging device is collapsible to a small diameter configuration which fits inside the distal end of the delivery catheter, and can pass through the lumen of the delivery catheter, for insertion into the body, navigation through the patient's vasculature, and deployment from the distal end. The bridging device, as illustrated, is in its expanded, large diameter configuration, which it assumes after ejection from the distal end of the delivery catheter.
The bridging device includes several radiopaque markers 46 disposed on the distal region. As illustrated, the distal markers are disposed on the distally pointing vertices of the distal-most zigzag segment of the device. Three markers are provided at this longitudinal location, the distal vertices of the distal zigzag segment 24. An additional marker 47 is disposed on a spiral strut near the distal region, marking the proximal extent of the distal region. Several radiopaque markers 48 are disposed at the central vertices of the central paired zigzag segment (in this embodiment, each central vertex is marked with its own marker). Also, a radiopaque marker 49 is disposed near the proximal region, on a spiral strut, marking the distal extent of the proximal region. As illustrated, the proximal marker is disposed on a spiral strut just distal to a distally pointing vertex of the proximal-most zigzag segment of the device. The radiopaque markers facilitate the method of placing the device, which is described below.
As appears from FIGS. 3 and 4 the first central zigzag segment 34 (which opposes the distal region) is characterized by distally pointing vertices, and the second central zigzag segment 35 (which opposes the proximal region) is characterized by proximally pointing vertices. The distally pointing vertices of the first central zigzag segment are joined by the spirally oriented struts 42 extending from an originating distally pointing vertex of the first central zigzag segment to a vertex of the distal zigzag segment 25 which is circumferentially displaced from the originating vertex. Likewise, the proximally pointing vertices of the second central zigzag segment 35 are joined by a spirally oriented strut extending from an originating proximally pointing vertex of the second central zigzag segment to a vertex of the proximal zigzag segment 29 which is circumferentially displaced from the originating vertex. The displacement may be one, two or three vertices or more (using a vertex of the zigzag segments as a unit of measure around the circumference of the device).
As shown in FIG. 9 a, the surgeon has inserted the delivery catheter 2, with the delivery wire disposed within the catheter, and the bridging device mounted on the distal tip of the delivery wire, through the patient's vasculature so that the distal tip of the catheter 2 is disposed within the posterior cerebral artery 14. With the catheter tip in the posterior cerebral artery 14, the surgeon pulls the delivery catheter proximally, while holding the bridging device distally, partially deploying it from the delivery catheter so that the distal region is outside the catheter and free to expand (superelastically or elastically, depending on the material comprising the device). Upon expansion, the distal region of the bridging device engages the inner wall of the posterior cerebral artery. The release of the distal region from the insertion catheter is seen under fluoroscopy. The struts and wires of the device will likely not be visible under current fluoroscopy systems, so the surgeon will rely on the radiopaque markers. In this first step, the distal set of markers 46 appears outside the delivery catheter, confirming that the distal region is deployed.
As shown in FIG. 9 b, the surgeon has withdrawn the insertion catheter 2 to release the region of the device bearing the radiopaque marker 47, which marks the proximal extent of the distal segment. The surgeon will deploy the device, pulling the device proximally or pushing it distally, to align this distal “edge” marker with the edge of the distal (farthest from the catheter tip) margin of the neck of the aneurysm, at this point or later in the method.
As shown in FIG. 9 c, the surgeon has further withdrawn the insertion catheter 2 to release the central region, so that region of the device bearing the radiopaque markers 48 is deployed, and the markers appear on the fluoroscope. All six of the central region radiopaque markers should be visible. The single edge marker is still visible near the distal margin, and the distal markers 46 are visible deeper in the posterior cerebral artery, confirming that the distal region 21 is still properly located.
As shown in FIG. 9 d, the surgeon has withdrawn the delivery catheter 2 to fully release the central region, so that the proximal radiopaque marker 49 appears on the fluoroscope. The surgeon will manipulate the device, pushing proximally and/or pulling distally, to align this distal “edge” marker with the edge of the proximal (nearest to the catheter tip) margin of the neck of the aneurysm, at this point or later in the method.
As shown in FIG. 9 e, the surgeon has pushed the delivery wire 43 distally, maintaining the delivery catheter 2 in position, to fully release the central region, to push the proximal region distally toward the bifurcation. This results in expansion of the central region, and spreading of the individual spiral struts and zigzag segments through the bifurcation, urging at least one or two of the struts or V-shaped elements into apposition with the aneurysm neck. This is indicated by the movement of the radiopaque markers toward the neck, as illustrated, so that the proximal radiopaque marker 49 appears on the fluoroscope. Again, the single distal edge marker is still visible near the distal margin, and the distal markers 46 are visible deeper in the posterior cerebral artery, confirming that the distal region 21 is still properly located within the posterior cerebral artery.
As shown in FIG. 9 f, the surgeon has continued manipulated the bridging device with the delivery wire 43, pushing and pulling as necessary to achieve the shape for the central region that best bridges the aneurysm neck.
As shown in FIG. 9 g, the surgeon has withdrawn delivery catheter 2 proximally, to fully release the bridging device, including the radiopaque marker 55 which is fixed that the distal end of the tethers. Further manipulations may be necessary to ensure that the central region struts and V-shaped elements are best located over the aneurysm neck, the distal edge marker is still co-located with the distal edge of the neck, and the proximal radiopaque marker 49 is co-located with the distal extent of the basilar artery. When the surgeon is satisfied with the placement, he operates a power supply connected to the electrolytic detachment joint 44 to sever the delivery wire 43 from the bridging device. Although it will not be visible under current imaging techniques, the bridging device is shown in this FIG. 9 g, to illustrate a typical placement. After detachment from the delivery wire, the bridging device is lodged within the bifurcation, with the proximal region expanded to engage the wall of the basilar artery, as shown in FIG. 9 g. While permanent implantation will usually be desired, the device may be used as a temporary scaffold to assist in placement of the coils, and the method may be completed in such cases by withdrawing the bridging device into the distal segment of delivery catheter and removing the bridging device from the bifurcation after delivering the occlusive device or substance.
Though the method is illustrated with specific reference to the basilar tip aneurysm, which occurs at the terminus of the basilar artery, the method can be used to treat bifurcation aneurysms at bifurcations of the middle cerebral artery 17, the internal carotid artery 5, the anterior communicating artery 19 (at the anterior cerebral artery 16), the superior cerebellar artery, the pericallosal artery (a continuation of the anterior cerebral artery), the posterior inferior cerebellar artery, or any other bifurcation. Each bifurcation is characterized by an inlet artery, and first outlet artery and a second outlet artery, which in the illustration of FIGS. 9 a through 9 g correspond to the basilar artery, the left posterior communicating artery and the right posterior communicating artery.
The bridging device can be made various configurations in which the number of zigzag segments is varied, the length of the segments or the length of the spiral struts is varied, or the number of V-shaped elements in the various zigzag segment is varied. These various embodiments are described in the following figures. FIG. 12 illustrates an embodiment of a protuberant aneurysm bridging device 61 assembled over a mandrel 62. The device 61 comprises a distal end region 21, comprising a zigzag segment 63 d comprising V-shaped segments 64 d and a proximal end region 22 comprising a zigzag segment 63 p comprising V-shaped segments 64 p, and a central region 23. The central region comprises two first intermediate spiral strut regions 65, each comprising a plurality of first intermediate spirally oriented struts 66, two second intermediate zigzag segments 67 d and 67 p each with a plurality of second intermediate V-shaped struts 68, and a plurality of spirally oriented center struts 69 joining vertices of the zigzag segment of the second intermediate V-shaped struts on either end of the spirally oriented center struts. This protuberant aneurysm bridging device can be symmetric about an axis running laterally to the longitudinal axis. FIG. 13 illustrates a side view of the protuberant aneurysm bridging device 61 clarifying the end regions 63 d and 63 p, the central region 69, and first intermediate strut regions 65. The spirally oriented struts that join each of the zigzag segments extend, as described in relation to the spirally oriented struts of FIGS. 3 and 4 , circumferentially around the volume defined by the device, from a vertex of one zigzag segment to a vertex of the next zigzag segment which is circumferentially displaced from the originating vertex. The displacement may be one, two or three vertices or more (using a vertex of the zigzag segments as a unit of measure around the circumference of the device).
The protuberant aneurysm bridging device 61 is fabricated by cutting a pattern. The pattern can be cut into a flat sheet of device material which is then rolled and the ends affixed to each other. The flat sheet embodiment can be fabricated using laser cutting, electrical discharge machining (EDM), wire EDM, photochemical etching, mechanically machined, or otherwise machined. In other embodiments, the device 61 can be cut from a tubular blank using methodology itemized above for the flat sheet embodiment.
The protuberant aneurysm bridging device 61 can be fabricated from materials such as nitinol, shape memory nitinol, martensitic nitinol, superelastic or pseudoelastic nitinol, stainless steel, titanium, cobalt nickel alloys, tantalum, and the like. The device 61 can be malleable or it can be elastically biased outward to be self-expanding.
Following machining, the protuberant aneurysm bridging device 61 can be expanded or dilated from a first, smaller inside diameter, to a second, larger inside diameter. The device 61 can next be temporarily affixed about the mandrel 62. The device 61 can next be selectively twisted to expand and re-configure specific regions, especially the spiral regions such as the central region 69 or one or both of the first intermediate regions 65. The device 61 can next be heat set to retain its shape. For example, when made of superelastic nitinol, the device 61 is fabricated from nitinol which can be heat set at temperatures of about 450° C. to about 550° C. while maintained in a specific shape, after which the temperature and restraint can be removed leaving the device in its final, unstressed configuration. Optional quenching, such as with water, can be used to rapidly cool the device 61. The heat set time can range from about 1 minute to about 15 minutes depending on mass, material, and temperatures used. FIG. 12 illustrates one of many configurations possible for a device using different flat patterns, different materials, different numbers of struts, and different strut thicknesses, widths, and lengths. The number of struts can vary between about 6 and about 16 or more, and preferably between about 8 and 14, with a generally similar number of slots interspaced between the struts.
Referring to FIG. 15 , the two first intermediate regions 80 are configured to provide bending out of the longitudinal axis. The central region 81 is further configured for axial bending. The two end regions 82 and the two second intermediate regions 83 comprise zigzag segments, maintain partial diamond, diamond, or wave structures that are generally stiff and resist bending out of the longitudinal axis but provide superior hoop strength and holding power within an artery or vessel. Furthermore, the central region 79 is generally loosely configured with large spaces between struts or elements and permits blood flow therethrough. The first intermediate regions 77 are further configured for greater open space than the end regions 76 or the second intermediate regions 78. The first intermediate region 77 can be beneficial when placed across a bifurcation or trifurcation outlet vessel and permit continued blood flow without embolization. The end regions 76 can be configured, as illustrated, with an outward taper to facilitate holding within the vessel wall.
In the illustrated embodiment, a preferred specification provides for three longitudinal cells and ten repeat patterns circumferentially. The width of the bars is about 65 micrometers and the wall thickness of the material is about 74 micrometers. The illustrated flat pattern 84 can be suitable for, or cut from, a tube having a diameter of about 2.464 mm. The diameter of the tubing blank can vary depending on the application. The wall thickness can vary from about 0.25 mm to about 0.5 mm to about 0.20 mm. The bar or strut width can vary from about 0.25 mm to about 0.1 mm with a preferred range of about 0.3 mm to about 0.5 mm.