Improving the visibility of mechanical thrombectomy devices in diagnostic imaging

Abstract

To provide an improved mechanical thrombectomy device having enhanced visibility during diagnostic imaging (e.g., fluoroscopy).SOLUTION: An expandable mechanical device for use during a thrombectomy medical procedure having enhanced visibility during imaging. Furthermore, the configuration of an eyelet 500 and / or strut optimizes retention of a marker 505 in the eyelet during the medical procedure without increasing overall profile of the strut.SELECTED DRAWING: Figure 5A

Description

[Technical field]

[0001] The present invention relates to intravascular medical systems, and more particularly to an improved mechanical thrombectomy device with improved visibility in diagnostic imaging. [Background technology]

[0002] Acute ischemic stroke is caused by a thrombotic or embolic obstruction (e.g., blockage) in a cerebral artery of the brain. The obstruction is typically caused by a blood clot dislodged from another part of the body that travels in an antegrade direction (the direction of normal blood flow) through the blood vessel and eventually lodges in a cerebral artery of the brain. The clot is subject to a pulsatile pressure gradient (i.e., systemic blood pressure acting on the proximal thrombus surface minus pressure from retrograde collateral blood flow at the distal thrombus surface) that can reduce the clot in the vessel over time and force it further into place. In addition, some degree of biological adhesion can occur between the clot and the inner wall of the blood vessel.

[0003] A procedure known as thrombectomy can be used to remove thrombi, blockages, obstructions, or clots lodged in blood vessels using mechanical devices. Thrombectomy treatment or procedures are typically performed on patients within a relatively short period after stroke (e.g., less than about 48 hours after stroke onset) and are best suited for large vessel blockages, typically having a diameter of greater than about 1.0 mm. Typically, imaging techniques such as, for example, angiograms, MRIs, CT, or CT angiograms (CT angiography, CTA) are used to determine whether thrombectomy treatment is suitable for that particular patient.

[0004] During a thrombectomy procedure or treatment, a physician or interventionalist introduces a guidewire intravascularly through the vasculature, typically into an artery located in the groin or arm, or by direct access through the carotid artery. The guidewire is advanced through the vasculature to the target location of the clot, obstruction, or occlusion. Once the guidewire is properly positioned, a microcatheter, typically having an outer diameter of less than about 1.0 mm, is tracked over the guidewire, which passes through a lumen defined axially through the microcatheter. The guidewire and microcatheter are used to cross the clot or occlusion using standard interventional techniques. A stent or mechanical thrombectomy device in a compressed state may be guided through the lumen of the microcatheter to the target site. The stent or mechanical thrombectomy device automatically expands to its native expanded state when deployed from the microcatheter. The stent or mechanical thrombectomy device is typically made of a biocompatible material, such as stainless steel, nickel-titanium, or tantalum.

[0005] The thrombectomy procedure is performed in a cardiac catheterization lab at a medical facility aided by imaging, typically fluoroscopy (i.e., continuous x-ray imaging). During the thrombectomy procedure, the interventionalist or physician deploys the thrombectomy device at the optimal location in the occlusion with the aid of imaging. Imaging can also help visualize the geometry of the vessel, the location of the thrombus in the mechanical thrombectomy device, and whether the thrombus is retracting (pulling proximally through the vessel) at substantially the same rate as the mechanical thrombectomy device. Imaging can also be used to determine whether there is an underlying stenosis in the vessel.

[0006] Conventional mechanical thrombectomy devices are typically constructed of Nitinol (55% by weight nickel, balance titanium) or other superelastic or shape-memory alloys. These alloys are deformable / compressible, but when deployed or heated, they automatically (i.e., without the need for any external physical force) return (remember) to their original undeformed shape. FIG. 1 shows a radial cross-section of a conventional wire 100 made entirely of a single material, e.g., Nitinol. Typically, laser cutting or other conventional techniques are used to create the desired pattern, e.g., an expandable mesh such as a scaffold or cage. In this example, five laser cuts are made radially inward from the outer diameter (OD) to the center (C) of the Nitinol wire to form five struts or pie-shaped wedges 105. Of course, any number of cuts may be made to form any desired number of struts or pie-shaped wedges, greater than or equal to two.

[0007] The shape memory alloy is then positioned on the mandrel and heated to define a second shape. Advantageously, the shape memory alloy provides a sturdy skeleton or frame while its elastic properties allow it to recover its original shape after being deformed so that it can be received within the lumen of the microcatheter. Because the mechanical device can be shaped by mechanical restraint and heat treatment, the Nitinol part can be manufactured into a shape that folds (wraps down) to a smaller or reduced radius when forced into the lumen of the catheter. When the mechanical device is removed from the distal end of the catheter, it automatically recovers or restores its larger radial shape. Despite these beneficial properties, one significant drawback associated with using shape memory alloys to manufacture mechanical thrombectomy devices is their relatively poor fluoroscopic visibility, i.e., relatively poor radiopacity. To circumvent this drawback, conventional mechanical thrombectomy devices are often designed to improve visibility during diagnostic imaging by incorporating additional radiopaque components (e.g., markers, etc.), such as platinum coils or gold rivets. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention relates to an improved mechanical thrombectomy device that provides improved visibility during diagnostic imaging (eg, fluoroscopy). [Means for solving the problem]

[0009] One aspect of the present invention relates to a thrombus removal device with improved visibility during diagnostic imaging.

[0010] Another aspect of the invention relates to an expandable mechanical device for use during a vascular medical procedure, the device comprising a strut having an eyelet defined therein, the eyelet having a geometry including at least one indent or outdent. A marker rivet is secured within the eyelet of the strut. The eyelet geometry may include one or more indents or outdents. Additionally, the indents or outdents of the eyelet may be symmetric mirror images of each other along a longitudinal axis and / or a lateral axis. In certain configurations, the eyelet geometry may be one of a butterfly bandage shape, a rocket shape, or a bowtie shape.

[0011] Yet another aspect of the invention relates to an expandable mechanical device for use during a vascular medical procedure, the device comprising a strut having an outer surface and an outer radial profile, the outer surface of the strut having a recess defined therein, the recess extending radially inward. The device further includes a U-shaped marker rivet received and secured within the recess of the strut. Once assembled, the overall radial profile of the assembly of the strut and the U-shaped marker rivet is equal to or less than the outer radial profile of the strut alone, and is preferably flush with one another. In such a configuration, the recess may be an annular groove, or an angled recess having a wedge-shaped radial cross-sectional profile.

[0012] Yet another aspect of the invention relates to an expandable mechanical device for use during a vascular medical procedure, the device comprising a plurality of struts having an eyelet defined in each of the plurality of struts, adjacent eyelets disposed along a longitudinal axis of the mechanical device radially offset relative to one another.

[0013] However, yet another aspect of the invention relates to an expandable mechanical device for use during a vascular medical procedure, the device comprising a strut having an eyelet defined therein, the eyelet having a tapered sidewall forming one or more stepped layers, and a marker rivet secured within the eyelet of the strut.

[0014] Yet another aspect of the invention relates to an expandable mechanical device for use during a vascular medical procedure, the device comprising a strut having an eyelet with a wall defined therein, the strut having a chamfer along at least one of an outermost upper edge or an innermost lower edge of the wall.

[0015] In accordance with the present invention, yet another aspect relates to an expandable mechanical device for use during a vascular medical procedure, the device comprising a strut having an eyelet and a strut profile defined therein, the eyelet having an S-shape, and a complementary S-shaped marker rivet secured within the S-shaped eyelet of the strut.

[0016] Another aspect of the invention relates to an expandable mechanical device for use during a vascular medical procedure, the device comprising a single strut defined between two adjacent crowns of an expandable medical device. The single strut has a set of eyelets defined therein, each of the eyelets in the set having a marker rivet secured therein. In one aspect of the invention, the eyelets in the set overlap one another in sequence, while in another aspect of the invention, the eyelets in the set are arranged linearly in sequence without overlapping. [Brief description of the drawings]

[0017] These and other features of the present invention will become more readily apparent from the following detailed description and drawings which illustrate the invention and in which like reference numerals refer to like elements throughout the several views. [Figure 1] FIG. 1 is a radial cross-section of a conventional prior art wire made of a single material (Nitinol) that is laser cut radially inward from the periphery to the center to form five pie-shaped wedges or segments. [Diagram 2] FIG. 1 is a radial cross-section of a prior art drawn filed tube (DFT) composite wire made from two different materials according to the present invention. An inner core made of a radiopaque material is surrounded by an outer metal layer. The composite wire is laser cut radially inward from the periphery to the center to form five equal sized pie-shaped wedges or segments. [Diagram 3] 3 shows one of the struts of FIG. 2 in an expanded state. [Figure 4A] FIG. 2 is a plan view of a single eyelet and associated radiopaque marker rivet in a prior art mechanical thrombectomy device prior to rivet crimping (i.e., prior to riveting). [Figure 4B]4B is a cross-sectional view of a single eyelet and associated radiopaque marker rivet in the prior art mechanical thrombectomy device of FIG. 4A taken along line 4B-4B. [Figure 4C] FIG. 4B is a plan view of a single eyelet and associated radiopaque marker rivet in the prior art mechanical thrombectomy device of FIG. 4A after the rivet has been crimped into place (i.e., post-riveting). [Figure 4D] FIG. 4D is a cross-sectional view of a single eyelet and associated radiopaque marker rivet in the prior art mechanical thrombectomy device of FIG. 4C taken along line 4D-4D. [Figure 5A] FIG. 2 is a plan view of a single eyelet and associated radiopaque marker rivet in a mechanical thrombectomy device according to the present invention prior to rivet crimping (i.e., prior to riveting). [Figure 5B] 5B is a cross-sectional view of a single eyelet and associated radiopaque marker rivet in the mechanical thrombectomy device of the present invention of FIG. 5A taken along line 5B-5B. [Figure 5C] 5C is a cross-sectional view of a single eyelet and associated radiopaque marker rivet in the mechanical thrombectomy device of the present invention of FIG. 5A taken along line 5C-5C. [Figure 5D] FIG. 5B is a cross-sectional view of a single eyelet and associated radiopaque marker rivet in the mechanical thrombectomy device of the present invention of FIG. 5A after the rivet has been crimped into place (i.e., after riveting). [Figure 5E] 5E is a cross-sectional view of a single eyelet and associated radiopaque marker rivet in the mechanical thrombectomy device of the present invention of FIG. 5D taken along line 5E-5E. [Figure 5F] 5F is a cross-sectional view of a single eyelet and associated radiopaque marker rivet in the mechanical thrombectomy device of the present invention of FIG. 5D taken along line 5F-5F. [Figure 6] 1 is a longitudinal cross-sectional view of a portion of a raw shape memory alloy tube according to the present invention having an annular shaped recess, channel or groove defined radially inwardly in a portion of its outer surface. [Figure 7] FIG. 2 is a radial cross-section of an exemplary laser cut mechanical device having four struts, each of which has a corresponding annular-shaped recess defined radially inwardly in its outer surface. [Figure 8] FIG. 8 is an enlarged partial radial cross-sectional view of a U- or C-shaped marker that is crimped or welded into an annular recess in one of the struts of FIG. 7, showing that when the parts are assembled, the marker does not extend radially outward beyond the outermost surface of the strut. [Figure 9A] FIG. 1 is a plan view of an exemplary outer cage having two proximal radiopaque markers, three distal radiopaque markers, and four intermediate radiopaque marker sets positioned therebetween (each set having four intermediate markers). [Figure 9B] FIG. 9B is a side view of the exemplary outer cage of FIG. 9A. [Figure 10] An exemplary expanded cage is shown in which the positions of multiple struts or segments and exemplary rivet eyelets are in a staggered (unaligned) radial configuration to allow for efficient wrapping of a small profile and improved fit over microcatheters with relatively narrow lumen diameters. [Figure 11A] FIG. 13 shows a portion of the laser cut pattern of the outer cage unfolded, illustrating eyelets that are staggered or offset along the axial or longitudinal direction of the outer cage for efficient wrapping of a small profile and improved fit for relatively small diameter microcatheters. [Figure 11B] FIG. 11B is a perspective view of a portion of the laser cut pattern of the outer cage of FIG. 11A in a pre-expanded compressed state, after rolling, showing the arrangement of eyelets offset longitudinally along the axial direction of the outer cage. [Figure 12A]FIG. 2 is a cross-sectional view of a prior art assembled strut defining an eyelet and an associated marker rivet secured within the eyelet, where the maker rivet does not have an overhang over the eyelet. [Figure 12B] FIG. 1 is a cross-sectional view of a prior art assembled strut defining an eyelet and associated marker rivet secured within the eyelet, creating an overhanging effect on both the outermost / upper surface and the lowermost / lower surface, resulting in a disadvantageous increase in the overall profile of each assembled part. [Figure 12C] FIG. 13 is a cross-sectional view of an assembled strut defining an eyelet having tapered or sloped sidewalls formed by offset laser cutting and an associated marker rivet secured within the eyelet to provide increased overhang effect and improved retention in accordance with the present invention. [Figure 12D] FIG. 1 is a cross-sectional view of an assembled strut defining an eyelet having tapered or sloped sidewalls with stepped or offset layers and an associated marker rivet secured within the eyelet to provide an increased overhang effect and improved retention in accordance with the present invention. [Figure 12E] FIG. 1 is a cross-sectional view of an assembled strut defining an eyelet having a single chamfer along its outermost / upper side and an associated marker rivet secured within the eyelet to provide a flare effect and improved retention in accordance with the present invention. [Figure 12F] FIG. 2 is a cross-sectional view of an assembled strut defining an eyelet having two chamfered portions along both its outermost / upper side and its opposing innermost / lower side, and an associated maker rivet secured within the eyelet, providing improved retention without creating a bulging effect and without increasing the overall profile, in accordance with the present invention. [Figure 13A] FIG. 13 is a top view of an exemplary S-shaped eyelet defined in a single strut and a complementary S-shaped marker rivet secured therein in accordance with the present invention. [Figure 13B] FIG. 1 is a top view of an exemplary single strut according to the present invention, the single strut having a series of multiple eyelets each having an associated marker rivet secured therein, where when viewed from a side view, the non-linearly arranged marker rivets that comprise the set overlap one another in a continuous series, creating the visual effect of a single continuous marker rivet rather than multiple individual marker rivets. [Figure 13C] FIG. 1 is a top view of an exemplary single strut according to the present invention having a series of eyelets each having an associated marker rivet secured thereto, where when viewed from the side, the marker rivets are arranged in a linear sequence (without overlap between them) providing a more distinctive visual observation than would be possible with a single marker rivet alone, making the particular set easily identifiable. [Figure 14A] FIG. 1 is a perspective view of a strut having an angled recess defined in its periphery. [Figure 14B] FIG. 14B is a top view of the angled recess of the strut of FIG. 14A. [Figure 14C] FIG. 14C is a cross-sectional view of the angled recess of the strut of FIG. 14A taken along line 14C-14C. [Figure 14D] FIG. 14B is a side view of the angled recess of the strut of FIG. 14A. [Figure 14E] FIG. 1 is a perspective view of an assembled strut having an angled recess defined on its periphery with a C-shaped or U-shaped marker secured therein. [Figure 14F] FIG. 14F is a cross-sectional view through the assembled strut of FIG. 14E taken along line 14F-14F, showing that when assembled, the C- or U-shaped markers do not extend radially outward beyond the outer diameter of the strut. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The terms "distal" or "proximal" are used in the following description with reference to a location or direction relative to the treating or interventionalist. "Distal" or "distally" is a location or direction away from the physician or interventionalist. "Proximal" or "proximal" or "proximal" is a location or direction closer to the physician or interventionalist. The terms "occlusion," "clot," or "obstruction" are used interchangeably.

[0019] Referring to FIG. 2, a radial cross-section of an exemplary prior art drawn filled tube (DFT) composite wire 200 for manufacturing a mechanical thrombectomy device is shown. The wire of FIG. 2 has an inner core 215 made of a first biocompatible material surrounded by an outer layer 210 of a second biocompatible material different from the first material. The first material forming the inner core 215 is made of a radiopaque material, i.e., a material that is opaque to one or another form of radiation, such as x-rays, so as to be visible during imaging. Preferably, the first material has a relatively high radiopacity, typically a high atomic number material (e.g., atomic number in the 70s), such as platinum, gold, tantalum, or tungsten. The second material comprising the outer layer 210 is a shape memory alloy, such as Nitinol (a nickel-titanium metal alloy). The shaped pultruded filled composite tube made of two different materials may then be cut radially inward, through the outer layer and inner core to the center (not completely through the wire), preferably using an ultra-high frequency laser. What is formed are a number of wedge or pie shaped struts. In the exemplary embodiment of FIG. 2, five wedge or pie shaped struts 205 are defined. Of course, the pultruded filled tube wire may be laser cut to define any number of one or more wedge or pie shaped struts as desired. Each strut may be expanded and heat set on a mandrel as in the manufacture of standard Nitinol devices.

[0020] From the single expanded strut 205 after polishing shown in Figure 3, it can be clearly seen that each strut made in accordance with the present invention (all struts of the drawn fill tube wire) includes a segment or portion of an inner core 215 made from a radiopaque material, such as platinum, in the exemplary embodiment shown. Because all struts include a portion made from a radiopaque material, the mechanical thrombectomy device can be completely, i.e., entirely, viewed during diagnostic imaging.

[0021] As discussed above, one or more markers made of a material (e.g., gold, platinum, or tantalum) having a radiopacity greater than that of the struts may be attached or secured to the struts of a stent to improve the radiopacity, i.e., visibility, of the mechanical thrombectomy device during diagnostic imaging. Figures 4A and 4B are plan views of a single eyelet or opening 400 in a strut of a prior art mechanical thrombectomy device (e.g., a stent) and an associated or corresponding single rivet 405 (made of a radiopaque material) without the rivet being yet crimped into the eyelet (i.e., prior to riveting). A cross-sectional view of the eyelet and corresponding rivet taken along line 4B-4B is shown in Figure 4B. This conventionally shaped eyelet is elliptical or oval, and the associated marker rivet also has an elliptical, oval, or rectangular cross-sectional profile (Figure 4A). As shown in the plan view of FIG. 4C, after crimping (i.e., after riveting), there is a contact or overlap area between the crimped marker rivet and the eyelet with a distance (d, d', d"). FIG. 4D is a cross-sectional view through the eyelet and rivet (after riveting) taken along line 4D-4D of FIG. 4C.

[0022] To prevent the riveted marker from falling out of the stent strut opening or eyelet, the present invention increases the retention of the rivet in the strut eyelet by increasing the contact area and overlap area. The cross-sectional profile of the eyelet design of the present invention shown in Figures 5A-5F has one or more indents / recesses and / or outdents / protrusions in the cross-sectional profile, unlike the conventional elliptical cross-sectional profile (without indents / recesses and / or outdents / protrusions) of the eyelets of the prior art stents (Figures 4A-4D). Preferably, the cross-sectional profile of the eyelet design of the present invention has multiple indents / recesses and / or outdents / protrusions. In the exemplary plan view of Figure 5A, the cross-sectional profile of the eyelet resembles the cross-sectional profile of a butterfly bandage, rocket shape, or bowtie. This preferred geometric configuration of the eyelet is preferably tapered from each side toward the center. That is, the sides are drawn inward toward each other as mirror images along line 5B-5B. Each indentation or recess 510 of the eyelet 500 of the present invention provides an increased or larger overlap area or surface (D, D', D") compared to the overlap area or surface (d, d', d") of a conventional rectangular or elliptical eyelet configuration (FIG. 4C). Here, overlap area or surface refers to the area of ​​the riveted marker that extends radially outward from the outer profile of the eyelet after crimping (i.e., after riveting). Due to this increased contact surface, the contact area between the sidewalls of the rivet and the sidewalls of the eyelet also increases. This increase in overlap area and contact surface improves retention of the riveted marker 505 in the corresponding eyelet 500. The number, location and arrangement of the indentations or recesses 510 of the eyelets of the present invention may be selected as desired to provide strong retention forces preferably targeted to areas most susceptible to bending, flexing and / or deformation during use.

[0023] Instead of riveting radiopaque markers into eyelets defined in the struts of the stent, the radiopacity of the mechanical thrombectomy device can also be improved by crimping a marker made of a radiopaque material (e.g., gold or platinum) directly onto a portion or segment of the strut itself. Unfortunately, such an approach results in an undesirable increase in overall profile, i.e., an increase in the outer diameter (OD) and / or a decrease in the inner diameter (ID) of the assembled device after crimping. Any increase in the overall profile of the marker can disadvantageously cause its leading edge to become a snag point during sheathing or resheathing. To overcome these problems, the outer surface or exterior profile of the super memory alloy tube 600 (e.g., Nitinol tube) of the present invention is machined to accommodate crimping or welding of a radiopaque marker without increasing the overall profile of the assembled part. Specifically, prior to laser cutting of the strut pattern, one or more annular recesses, channels or grooves 605 are defined radially inward by removing only a portion of the outer surface of the raw supermemory alloy tube 600, as shown in FIG. 6. Note that the annular recesses, channels or grooves do not extend all the way through to the inner lumen 610. The one or more annular recesses, channels or grooves 605 may be ground, laser machined, or any other conventional technique for removing only a portion of the outer surface of the supermemory alloy tube material 610. A single annular recess, channel or groove 605 is shown in the partial longitudinal view of FIG. 6 of the raw supermemory alloy tube 600 (before it is laser cut to the desired pattern and heated). However, as previously discussed, any number of one or more annular recesses, channels or grooves 605 may be defined in the outer surface of the tube. The annular recesses, channels or grooves 605 are located where desired radiopaque markers are to be placed. The annular recess, channel or groove 605 has a radially inward depth "r" measured from the outermost circumference of the tube to the bottom of the opposing annular recess, channel or groove, which depth "r" typically varies from about 10% to about 50% of the wall thickness.The radially inward depth "r" is preferably about 25-50 μm and is sufficient to allow the U- or C-shaped markers to be crimped inwardly without the U- or C-shaped markers extending radially outwardly beyond the outer diameter of the strut, rather the U- or C-shaped markers are preferably flush with the outer diameter of the strut.

[0024] Once material has been removed from the outer surface of the supermemory alloy tube to form one or more annular recesses, channels or grooves, the processed tube may then be laser cut into the desired strut pattern such that these recesses may be aligned with the primary strut locations of the device after expansion of the device. In the exemplary radial cross-sectional profile of FIG. 7, the superelastic shape memory alloy tube is laser cut into the desired pattern having four struts (615a, 615b, 615c, 615d), each with an associated annular recess, channel or groove (605a, 605b, 605c, 605d) defined radially inward by removing a portion of the outer surface of the associated strut. Any number of one or more struts may be formed, each with an associated annular recess, channel or groove, as desired. Each marker is crimped or welded into a corresponding recess defined in the strut.

[0025] 8 is a cross-sectional view of a single U- or C-shaped marker 620 crimped into an annular recess, channel, or groove defined in a strut 615c. The annular recess, channel, or groove defined in the outer surface of the strut results in the outermost perimeter of the U- or C-shaped marker 620 not extending radially outwardly from the perimeter of the outermost diameter of the strut 615c. Thus, the overall profile of the assembled part is not increased (i.e., the outermost perimeter of the U- or C-shaped marker is either flush with or radially inward from the outermost diameter (OD) of the strut), thus eliminating the risk of potential snagging.

[0026] An alternative configuration is shown in Figures 14A-14F, where angled laser cuts are made on the strut resulting in the removal of wedge or pie shaped portions from the strut. Figure 14A is a perspective view of an exemplary strut 1400 having pie or wedge shaped recesses 1405 formed by several angled laser cuts. Top and side views of the pie or wedge shaped recesses of the strut of Figure 14A are shown in Figures 14B and 14D, respectively, while a partial cross-sectional view of the pie or wedge shaped recesses of the strut of Figure 14A taken along line 14C-14C is shown in Figure 14C. After one or more angled laser cuts are made on the strut, C- or U-shaped markers 1410 are crimped, crimped or welded into the corresponding recesses as shown in the perspective view of the assembled device in Figure 14E. As shown in Figure 14F, angled laser cuts into the struts are made so that the markers do not extend radially outward beyond the outer diameter of the strut when assembled. Preferably, the C- or U-shaped markers are flush with the outer diameter of the strut.

[0027] 9A and 9B are top and side views, respectively, of an exemplary outer cage 900 of a mechanical thrombectomy device. In this exemplary embodiment, the cage 900 has two radiopaque markers 905a, 905b at a proximal end, three radiopaque markers 910a, 910b, 910c at an opposing distal end, and a set of four intermediate markers (915a, 915b, 915c, 915d) therebetween, where each intermediate marker set includes four intermediate markers. Specifically, the first intermediate marker set 915a includes four intermediate marker segments (915a1, 915a2, 915a3, 915a4), the second intermediate marker set 915b includes four intermediate marker segments (915b1, 915b2, 915b3, 915b4), the third intermediate marker set 915c includes four intermediate marker segments (915c1, 915c2, 915c3, 915c4), and the fourth intermediate marker set 915d includes four intermediate marker segments (915d1, 915d2, 915d3, 915d4). Any number of one or more radiopaque markers may be positioned along the struts of the cage at the proximal end, distal end, or intermediate therebetween.

[0028] FIG. 10 is a perspective view of a portion of an exemplary cage 1000 in an expanded state. FIG. 10 shows a strut or segment 1005 having four exemplary eyelet (1010a-d) locations for receiving associated rivets made of radiopaque marker material. The eyelets 1010a-d, and therefore the radiopaque marker rivets received therein, are not radially aligned. Rather, eyelets 1010a and 1010c are radially aligned, while 1010b and 1010d are staggered proximally or distally. Staggering the eyelets, and therefore the radiopaque marker rivets therein, so as to be radially unaligned advantageously allows the cage to more efficiently wrap down to a smaller diameter to be accommodated in a catheter.

[0029] 11A and 11B show the laser cut pattern of the outer cage. Specifically, FIG. 11A shows a portion of the laser cut pattern of the outer cage 1100 in a flat, unfolded state. As can be clearly seen from this view, adjacent eyelets 1110a-1110e are offset or staggered relative to one another in the longitudinal or axial direction along the outer cage 1100. Specifically, eyelet 1110a is offset relative to 1110d. Staggering or offsetting the eyelets facilitates a relatively low profile and efficient wrapping of the outer cage in a compressed state, which enhances its suitability for receipt in a lumen defined within a relatively small diameter microcatheter. A portion of the laser cut pattern of the outer cage 1100 in a rolled configuration and prior to expansion is shown in a perspective view in FIG. 11B. FIG. 11B also shows that adjacent eyelets (1110a-1110e) are staggered or offset relative to one another in the longitudinal or axial direction of the cage.

[0030] Each marker rivet is secured in place within an associated eyelet defined in the strut to prevent it from falling out during a medical procedure. Retention of the marker within the eyelet is sufficient to resist forces acting in the direction of the strut outward and inward, which tend to cause the rivet to fall out. Overhanging the marker over the overhang of the eyelet is a typical method used to improve the fixation of the part, but has the drawback of resulting in an increase in overall profile. FIG. 12A is a cross-sectional view of a prior art rivet 1210a assembled within an associated eyelet 1200a. The eyelet 1200a has side walls 1215a that are substantially parallel in this configuration, forming a rectangular or square wedge strut cross section 1205a. In this design, the rivet does not overhang the eyelet of the strut, and the side walls are not very, if at all, angled. This makes it easier for the marker to fall out of the eyelet during a medical procedure. It is also known in the prior art to have a marker rivet 1210b overhang both on the upper and lower sides of the parallel side walls forming the eyelet 1200b, as shown in FIG. 12B. This design reduces the occurrence of dislodgement at the expense of an increase in overall profile due to the overhang. A modified design with an eyelet 1200c according to the present invention is shown in FIG. 12C. The side walls 1215c of the eyelet 1200c are cut with a laser offset from the tube centerline to be highly sloped or tapered (like a trapezoid) where the innermost / lower side has the smallest separation between the opposing sides and the outermost / upper side has the largest separation between the opposing sides. The rivet 12010c secured to the eyelet 1200c has an overhang only on the innermost / lower side (where such an increase in profile is less of a problem) and does not overhang the outermost / upper side.The sloped side walls provide particularly good retention against forces acting to push the marker towards the inside or central axis of the device, while the overhang on the innermost surface provides particularly good retention against forces acting to push the marker from the inside of the device towards the outside.

[0031] It is therefore desirable to develop an even more improved design for holding a marker securely within an eyelet defined in a strut without undesirably sacrificing increased overall profile and difficulty in wrapping down a mechanical device during delivery through a microcatheter. The novel design of the present invention has a tapered or angled sidewall 1215d of the eyelet 1200d that is further defined by multiple steps or offset tapered layers defined in the strut 1205d (FIG. 12D). Such steps or layers in the tapered or angled sidewall 1215d are beneficial because they can be manufactured using standard laser configurations by cutting a series of rings of decreasing diameter. This provides the same benefits as the design shown in FIG. 12C, but without the need for off-center laser cutting. In the cross-sectional views of Figures 12E and 12F, the strut cross-sectional walls (1215e, 1215f) each have a single (only on the outermost / upper side) or two chamfers (chamfered on both the outermost / upper side and the innermost / lower side) defined on the strut. A chamfer is defined herein as an inclined or sloping surface at the edge or corner of a sidewall of a strut. On the one hand, the single chamfer configuration creates an overhang effect only along the inner side where increased profile or volume is less of an issue, but there is no overhang profile on the outermost / upper side. On the other hand, the two chamfer design provides enhanced retention without any increase in profile (either along its outermost / upper side or innermost / lower side). An offset laser can be used to create the single or two chamfer configurations of Figure 12E.

[0032] Mechanical thrombectomy procedures are typically performed under fluoroscopy, and radiopaque markers on the mechanical thrombectomy device provide the interventionalist with a visual indication of the device's location and expansion / contraction state during the medical procedure. By way of example, information provided to the interventionalist using visual indications during the medical procedure may include the location of the device in the microcatheter during delivery, the expansion of the device during deployment, changes in the expansion of the device during retrieval, etc.

[0033] Radiopaque markers arranged as clearly defined rings around the circumference at multiple locations along a mechanical device provide observable information to a physician or interventionalist during a medical procedure. Typically, there are two fluoroscopic views used by a physician or interventionalist during a procedure: an anterior-posterior view (parallel to the patient's torso) and a lateral view (parallel to the patient's side). Identifying which ring a particular marker belongs to can be beneficial and can be a challenge for the physician or interventionalist.

[0034] The present invention seeks to improve the visibility of the markers and to easily distinguish which marker ring each individually identified marker belongs to by geometrically differentiating the markers in each ring around the circumference, thereby enabling the physician or interventionist to determine the expansion / contraction state of the device at distinct locations along the length of the device where each marker is located.

[0035] In accordance with the present invention, differentiation or identification of markers during imaging is achieved without increasing the overall profile of the device or adversely affecting performance (e.g., increased delivery force when advanced through a microcatheter). The top view of FIG. 13A shows an assembled S-shaped eyelet 1300a defined in a strut 1305a with a complementary S-shaped marker 1310a secured therein. By varying the shape of the individual marker rivets, such as by lengthening them, the rivets become more distinct and easily visible during imaging. Alternatively, instead of a single marker secured within a single eyelet, a single crown or single strut (defined as the segment between adjacent crowns) of the device having a series of multiple markers secured within associated eyelets may enhance marker visibility without increasing the overall profile of the device. FIG. 13B is a top view of an exemplary single strut having a series of multiple eyelets, each having an associated marker rivet secured therein, in accordance with the present invention. When viewed from various perspectives, a set of multiple markers will be more visible than a single marker rivet secured to an associated single eyelet defined in a single strut. For example, when viewed from a partial side-oblique perspective view, a series of marker rivets for a single strut overlap one another in a continuous series, creating the visual effect of a single continuous marker rivet rather than a series of multiple separate and independent marker rivets with the same overall volume of radiopaque material.

[0036] FIG. 13C is a top view of an alternative exemplary single strut having a series of eyelets arranged in a linear fashion, each having an associated marker rivet secured therein, according to the present invention. When viewed from different perspectives, these sets of markers are more visible than a single marker. For example, when viewed from an end or side, the marker rivets are arranged in a linear sequence (without overlap between them) or other uniform configuration that provides a more discriminative visual observation than would be provided by a single marker rivet alone at a single eyelet defined in a single strut. Such novel features described in FIGS. 13A-13C may be utilized to provide a strut at any desired location (e.g., edge or perimeter) that is easily identifiable and visible during imaging. Although each set shown in FIGS. 13B and 13C includes three markers, any number of two or more markers in a sequence may be used as desired.

[0037] The features of the invention as illustrated and described may be used in mechanical thrombectomy procedures, but are also suitable for use in other neurovascular or endovascular medical procedures.

[0038] Although the basic novel features of the present invention as applied to the preferred embodiment thereof have been shown, described and pointed out, those skilled in the art will appreciate that various omissions, substitutions and changes in the form and details of the illustrated systems / apparatuses, and in their operation, may be made without departing from the spirit and scope of the present invention. For example, all combinations of elements and / or steps that perform substantially the same functions in substantially the same manner to achieve the same results are expressly intended to be encompassed within the scope of the present invention. Also, the substitution of elements from one embodiment described above for another embodiment is fully intended and anticipated. It should also be understood that the drawings are not necessarily drawn to scale and are merely conceptual. It is therefore intended to be limited only by the scope of the appended claims.

[0039] All issued patents, pending patent applications, publications, articles, books, or other references cited herein are hereby incorporated by reference in their entirety.

[0040] [Embodiment] (1) An expandable mechanical device for use during a vascular medical procedure, said device comprising: a strut having an eyelet defined therein, the eyelet having a geometric shape including at least one indent or outdent; a marker rivet secured within the eyelet of the strut. (2) The expandable mechanical device of embodiment 1, wherein the geometric shape of the eyelet includes more than one indent or outdent. (3) The expandable mechanical device of embodiment 2, wherein the geometric shape of the eyelet includes indents or outdents that are symmetric mirror images of each other along the longitudinal and / or lateral axes. (4) The expandable mechanical device of embodiment 1, wherein the geometric shape of the eyelet is one of a butterfly bandage shape, a rocket shape, or a bowtie shape. (5) An expandable mechanical device for use during a vascular medical procedure, said device comprising: a strut having an outer surface and an outer radial profile, the outer surface of the strut defining a recess, the recess extending radially inward; and a U-shaped marker rivet received and secured within the recess of the strut, wherein an overall radial profile of the assembly of the strut and the U-shaped marker rivet is equal to or less than the outer diameter radial profile of the strut alone.

[0041] (6) The expandable mechanical device of embodiment 5, wherein the recess is an annular groove or an angled recess having a wedge-shaped radial cross-sectional profile. (7) An expandable mechanical device for use during a vascular medical procedure, said device comprising: An expandable mechanical device comprising a plurality of struts, each of the plurality of struts having an eyelet defined therein, the arrangement of adjacent eyelets along a longitudinal axis of the mechanical device being radially offset relative to one another. (8) An expandable mechanical device for use during a vascular medical procedure, said device comprising: a strut having an eyelet defined therein, the eyelet having a tapered sidewall; a marker rivet secured within the eyelet of the strut. (9) The expandable mechanical device of embodiment 8, wherein the tapered sidewall forms at least one stepped layer. (10) The expandable medical device of claim 8, wherein the tapered sidewall forms a plurality of stepped layers.

[0042] (11) The expandable medical device of claim 8, wherein the marker rivet forms a protrusion only on an innermost surface of the strut. (12) An expandable mechanical device for use during a vascular medical procedure, said device comprising: 1. An expandable mechanical device comprising: a strut having an eyelet with a wall defined therein, the strut having a chamfer along at least one of an outermost upper edge or an innermost lower edge of the wall of the strut. (13) The expandable mechanical device of embodiment 12, wherein the chamfer is at the outermost upper edge of the wall of the eyelet. (14) The expandable mechanical device of embodiment 12, wherein the chamfered portions are at the outermost upper edge and the innermost lower edge of the wall of the eyelet. (15) An expandable mechanical device for use during a vascular medical procedure, said device comprising: a strut having an eyelet and a strut profile defined therein, the eyelet having an S-shape; and a complementary S-shaped marker rivet secured within the S-shaped eyelet of the strut.

[0043] (16) An expandable mechanical device for use during a vascular medical procedure, said device comprising: a single strut defined between two adjacent crowns of the expandable medical device, the single strut having a set of a plurality of eyelets defined therein; a marker rivet secured within each of the plurality of eyelets in the set. (17) The expandable mechanical device of embodiment 16, wherein the eyelets in the set overlap one another contiguously. (18) The expandable mechanical device of embodiment 16, wherein the eyelets in the set are arranged linearly and consecutively in sequence without overlapping.

Claims

1. 1. An expandable mechanical device for use during a vascular medical procedure, the expandable mechanical device comprising: a strut having an upper surface, an opposing lower surface, and an eyelet defined therein by an inner sidewall of the strut extending from the upper surface to the opposing lower surface, the eyelet having a geometric shape including at least one recess; a marker rivet disposed within the eyelet of the strut; in a pre-crimped state, no portion of an outer surface of the marker rivet physically contacts the inner sidewall of the strut in which the eyelet is defined; In a crimped state, the marker rivet forms an overlap region covering the upper and lower surfaces of the strut radially outwardly of the inner sidewall of the strut that defines the eyelet; An expandable mechanical device, wherein in the pre-crimped state, the marker rivet has a geometric shape including at least one depression, the at least one depression aligned with a corresponding at least one recess in the eyelet of the strut along a lateral axis of the eyelet.

2. The expandable mechanical device of claim 1 , wherein the geometric shape of the eyelet includes more than one of the recesses.

3. The expandable mechanical device of claim 2 , wherein the geometric shape of the eyelets includes the recesses that are symmetric mirror images of each other along the longitudinal axis and / or the lateral axis.

4. 10. The expandable mechanical device of claim 1, wherein the geometric shape of the eyelet is one of a butterfly bandage shape, a rocket shape, or a bowtie shape.

5. 4. The expandable mechanical device of claim 3, wherein the eyelet has first and second sides extending along the longitudinal axis and third and fourth sides extending along the transverse axis, and the at least one recess includes a first recess defined in the first side, a second recess defined in the second side, and a third recess defined in the third side.

6. The expandable mechanical device of claim 5 , wherein the fourth side does not have the at least one recess defined therein.

7. The expandable mechanical device of claim 5 , wherein the at least one recess of the marker rivet includes a first recess corresponding to the first recess and a second recess corresponding to the second recess.

8. 2. The expandable machinery device of claim 1, wherein the marker rivet, in the crimped state, includes an upper portion overlying the upper surface and defining the overlapping area, a lower portion overlying the lower surface and defining the overlapping area, and an intermediate portion extending between the upper and lower portions, wherein a gap exists along the entire outer surface of the intermediate portion and the inner sidewall of the strut in which the eyelet is defined.

9. The expandable mechanical device of claim 8 , wherein the upper portion is elliptical when viewed from the upper side and the lower portion is elliptical when viewed from the lower side.

10. The expandable machinery of claim 1 , wherein the marker rivet is secured within the eyelet of the strut by crimping.

11. 2. The expandable mechanical device of claim 1, wherein the inner sidewall of the strut in which the eyelet is defined has a chamfer on at least one of an upper edge along the upper side and a lower edge along the lower side.

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