Improved visibility of mechanical thrombectomy devices during diagnostic imaging

Abstract

The present invention is entitled "Improved Visibility of Mechanical Thrombectomy Devices During Diagnostic Imaging." The present invention provides a stretchable mechanical device for use during a thrombectomy medical procedure that has enhanced visibility during imaging. Furthermore, the configuration of the eyelets and / or struts optimizes retention of markers in the eyelets during the medical procedure and does not increase the overall profile of the struts.

Description

BACKGROUND TECHNICAL FIELD

[0002] The present invention relates to intravascular medical systems. In particular, the present invention relates to improved mechanical thrombectomy devices with enhanced visibility during diagnostic imaging.

[0003] Related Art

[0004] Acute ischemic stroke is caused by a thrombotic or embolic occlusion (e.g., blockage) in a cerebral artery of the brain. The occlusion is typically caused by a blood clot released from another part of the body that travels in an antegrade direction (along the direction of normal blood flow) through the blood vessel and eventually becomes lodged in a cerebral artery of the brain. The clot is subject to a pulsatile pressure gradient (i.e., the systemic blood pressure acting on the proximal thrombus face minus the pressure from retrograde collateral blood flow at the distal thrombus face) that can compress the clot in the blood vessel and further wedge it into place over time. Additionally, some degree of bioadhesion can occur between the clot and the inner wall of the blood vessel.

[0005] A procedure known as thrombectomy can be used to remove a thrombus, occlusion, blockage, or clot lodged in a blood vessel using a mechanical device. Thrombectomy treatment or procedures are typically performed on a patient within a relatively short time after a stroke (e.g., within a time period of less than about 48 hours after the stroke occurs) and are best suited for large vessel occlusions that typically have a diameter greater than about 1.0 mm. Imaging (e.g., angiography, MRI, CT, or CT angiography (CTA)) is typically used to determine if a thrombectomy treatment is appropriate for that particular patient.

[0006] During a thrombectomy procedure or treatment, a physician or interventionalist accesses the vasculature, typically in an artery located in the groin or arm, or directly through the carotid artery. A guidewire is advanced through the vasculature to the target location of the clot, blockage, or occlusion. Once the guidewire is properly positioned, a microcatheter having an outer diameter that is typically less than about 1.0 mm is tracked over the guidewire, which passes through a lumen defined by the microcatheter. The guidewire and microcatheter are used to cross the clot or occlusion using standard interventional techniques. A stent or mechanical thrombectomy device can be directed through the lumen of the microcatheter to the target site while in a compressed state. Upon deployment from the microcatheter, the stent or mechanical thrombectomy device automatically expands to its initial enlarged state. The stent or mechanical thrombectomy device is typically made of a biocompatible material, such as stainless steel, nitinol, or tantalum.

[0007] Thrombectomy procedures are performed in a cardiac catheterization lab at a medical facility assisted by diagnostic imaging, typically fluoroscopy (i.e., continuous x-ray imaging). During the thrombectomy procedure, diagnostic imaging helps the interventional physician or practitioner to deploy the thrombectomy device at the optimal location of the occlusion. It can also help to visualize the shape of the vessel, the location of the thrombus on the mechanical thrombectomy device, and whether the thrombus is retracting (being withdrawn proximally through the vessel) at substantially the same speed as the mechanical thrombectomy device. Diagnostic imaging can also be used to determine whether there are underlying stenoses in the vessel.

[0008] Conventional mechanical thrombectomy devices are typically constructed from nitinol (55% by weight nickel, the rest being titanium) or other super-elastic or shape-memory alloys that are deformable / compressible but automatically (i.e., without the need to apply any external physical force) recover (“remember”) to their initial shape before deformation upon deployment or heating. Figure 1 is a radial cross-sectional view of a conventional wire 100 made of only a single material, such as nitinol. The desired pattern, such as an expandable mesh, like a skeleton or cage, is typically formed using laser cutting or other conventional techniques. In this example, five laser cuts are made radially inward from the outer diameter (OD) of the nitinol wire to the center (C) to form five struts or pie-shaped wedges 105. Of course, any number of cuts can be made to form the desired number of two or more struts or pie-shaped wedges.

[0009] The shape-memory alloy is then shaped into a second shape by being positioned over a mandrel and heated. The shape-memory alloy advantageously provides a strong skeleton or framework, while its elastic properties allow it to recover to its initial shape after deformation, so as to be able to be received within the lumen of a microcatheter. Since the shape of the mechanical device can be shaped by mechanical constraint and heat treatment, the nitinol sheet can be manufactured to collapse (wind) into a smaller or reduced radius geometry after being forced into the catheter lumen. Once the mechanical device is unsheathed from the distal end of the catheter, it automatically recovers or reverts to its larger radius geometry. Despite these advantageous features, one significant drawback associated with the use of shape-memory alloys to manufacture mechanical thrombectomy devices is their relatively poor visibility under fluoroscopic imaging, i.e., their relatively low radiopacity. To circumvent this drawback, conventional mechanical thrombectomy devices are typically designed to incorporate additional radiopaque components (e.g., markers), such as platinum coils or gold rivets, to improve visibility during diagnostic imaging.

[0010] The present invention relates to improved mechanical thrombectomy devices with enhanced visibility during diagnostic imaging, such as fluoroscopy. SUMMARY

[0011] One aspect of the present invention relates to a thrombectomy device with improved visibility during diagnostic imaging.

[0012] Another aspect of the present application relates to a stretchable mechanical device for use during a vascular medical procedure, wherein the device comprises a strut having an eyelet defined therein, the eyelet having a geometry comprising at least one notch or protrusion. A marker rivet is secured within the eyelet of the strut. The geometry of the eyelet can comprise one or more notches or protrusions. Additionally, the notches or protrusions in the eyelet can be mirror images of each other along a longitudinal axis and / or a transverse axis. In a particular configuration, the geometry of the eyelet can be one of a bowtie, a rocket, or a cravat shape.

[0013] Yet another aspect of the present application relates to a stretchable mechanical device for use during a vascular medical procedure, comprising a strut having an outer surface and an outer diameter radial profile, wherein a recess is defined in the outer surface of the strut and extends radially inward. The device further comprises a U-shaped marker rivet received and secured within the recess of the strut. After assembly, the overall radial profile of the assembly of the strut and the U-shaped marker rivet is equal to or smaller than the outer diameter radial profile of the individual strut, preferably flush with each other. In such a configuration, the recess can be an annular groove or an angled recess having a wedge-shaped radial cross-sectional profile.

[0014] Yet another aspect of the present application relates to a stretchable mechanical device for use during a vascular medical procedure, the device comprising a plurality of struts, each strut having an eyelet defined therein. Adjacent eyelets are positioned along a longitudinal axis of the mechanical device, radially offset with respect to each other.

[0015] Yet another aspect of the present application relates to a stretchable 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. A marker rivet is secured within the eyelet of the strut.

[0016] Yet another aspect of the present application relates to a stretchable mechanical device for use during a vascular medical procedure, the device comprising a strut having an eyelet defined therein, the eyelet having a wall. At least one of an outermost top edge or an innermost bottom edge along the wall of the strut has a chamfered cut.

[0017] According to the present application, another aspect relates to a stretchable mechanical device for use during a vascular medical procedure, the device comprising a strut having a strut profile and an eyelet defined therein, wherein the eyelet has an S-shape. A complementary S-shaped marker rivet is secured within the S-shaped eyelet of the strut.

[0018] Another aspect of the invention relates to a stretchable mechanical device for use during vascular medical procedures, the device comprising a single strut defined between two adjacent coronals of the stretchable medical device. The single strut has a plurality of eyelets defined therein; and a marker rivet is fixed within each of the plurality of eyelets in the plurality of eyelets. In one aspect of the invention, the plurality of eyelets in the plurality of eyelets are arranged in series and overlap each other, while in another aspect of the invention, the plurality of eyelets in the plurality of eyelets are arranged linearly in series one after another without overlapping. Attached Figure Description

[0019] The above and other features of the invention will become more apparent from the following detailed description and accompanying drawings, exemplified by the invention, wherein similar reference numerals throughout the views refer to similar elements, and wherein:

[0020] Figure 1 It is a radial cross-sectional view of a conventional line made of a single material (Nitinol), which has been laser-cut radially inward from its outer periphery to its center to form five disc wedges or segments;

[0021] Figure 2 This is a radial cross-sectional view of a prior art drawn tube (DFT) composite wire made of two different materials according to the present invention; the inner core formed of a radiopaque material is surrounded by an outer metal layer; the composite wire has been laser-cut radially inward from its outer periphery to its center to form five equal-sized disc wedges or segments;

[0022] Figure 3 yes Figure 2 One of the stretching struts;

[0023] Figure 4A It is a plan view of a single eyelet and associated radiopaque marking rivet of a prior art mechanical thrombectomy device before rivet crimping (i.e., before riveting).

[0024] Figure 4B yes Figure 4A A cross-sectional view of a single orifice and associated radiopaque marking rivet along line 4B-4B of a prior art mechanical thrombectomy device;

[0025] Figure 4C yes Figure 4A A plan view of a single orifice and associated radiopaque marking rivet of a prior art mechanical thrombectomy device in which the rivet is pressed into place (i.e., after riveting).

[0026] Figure 4D yes Figure 4C A cross-sectional view of a single orifice and associated radiopaque marker rivet along line 4D-4D of a prior art mechanical thrombectomy device;

[0027] Figure 5A is a plan view of a single eyelet and associated radiopaque marker rivet of the mechanical thrombectomy device of the present invention prior to rivet crimping (i.e., pre-riveting);

[0028] Figure 5B is a plan view of a single eyelet and associated radiopaque marker rivet of the mechanical thrombectomy device of the present invention prior to rivet crimping (i.e., pre-riveting); Figure 5A is a cross-sectional view of a single eyelet and associated radiopaque marker rivet of the mechanical thrombectomy device of the present invention along line 5B-5B;

[0029] Figure 5C is a cross-sectional view of a single eyelet and associated radiopaque marker rivet of the mechanical thrombectomy device of the present invention along line 5C-5C; Figure 5A is a cross-sectional view of a single eyelet and associated radiopaque marker rivet of the mechanical thrombectomy device of the present invention along line 5C-5C;

[0030] Figure 5D is a cross-sectional view of a single eyelet and associated radiopaque marker rivet of the mechanical thrombectomy device of the present invention after the rivet has been crimped into place (i.e., post-riveting); Figure 5A is a cross-sectional view of a single eyelet and associated radiopaque marker rivet of the mechanical thrombectomy device of the present invention after the rivet has been crimped into place (i.e., post-riveting);

[0031] Figure 5E is a cross-sectional view of a single eyelet and associated radiopaque marker rivet of the mechanical thrombectomy device of the present invention along line 5E-5E; Figure 5D is a cross-sectional view of a single eyelet and associated radiopaque marker rivet of the mechanical thrombectomy device of the present invention along line 5E-5E;

[0032] Figure 5F is a cross-sectional view of a single eyelet and associated radiopaque marker rivet of the mechanical thrombectomy device of the present invention along line 5F-5F; Figure 5D is a cross-sectional view of a single eyelet and associated radiopaque marker rivet of the mechanical thrombectomy device of the present invention along line 5F-5F;

[0033] Figure 6 is a longitudinal cross-sectional view of a portion of a raw shape memory alloy tube according to the present invention having a radially inwardly defined annular recess, groove, or channel on a portion of its outer surface;

[0034] Figure 7 is a radial cross-sectional view through an exemplary laser-cut mechanical device having four struts, each having a corresponding radially inwardly defined annular recess on its outer surface;

[0035] Figure 8 is a magnified partial radial cross-sectional view of a U-shaped or C-shaped marker forged or welded within the annular recess of one of the struts in Figure 7 showing that the marker does not extend radially outward beyond the outermost surface of the strut when the components are assembled together;

[0036] Figure 9A is a plan view of an exemplary outer cage having two proximal radiopaque markers, three distal radiopaque markers, and four sets of intermediate radiopaque markers (each set having four intermediate markers) disposed therebetween;

[0037] Figure 9B is Figure 9A a side view of an exemplary outer cage;

[0038] Figure 10 shows an exemplary stretched cage including a plurality of struts or segments, also showing exemplary rivet eyelet locations in a staggered (misaligned) radial configuration to facilitate reduced profile efficient wrapping and compatibility with microcatheters having relatively smaller diameter lumens;

[0039] Figure 11A is a portion of a laser cut pattern of an outer cage showing eyelets staggered or offset along the axial or longitudinal direction of the outer cage to facilitate reduced profile efficient wrapping and compatibility with relatively smaller diameter microcatheters;

[0040] Figure 11B is Figure 11A a perspective view of a portion of a laser cut pattern of an outer cage of

[0041] Figure 12A is a cross-sectional view of a prior art assembled strut defining an eyelet and an associated marker rivet secured therein, and the marker rivet does not have any overhanging portion above the eyelet;

[0042] Figure 12B is a cross-sectional view of a prior art assembled strut defining an eyelet and an associated marker rivet secured therein, creating an overhanging effect at both the outermost / top surface and the lowermost / bottom surface, thereby disadvantageously increasing the overall profile of the assembled component;

[0043] Figure 12C is a cross-sectional view of an assembled strut according to the present invention defining an eyelet having tapered or angled sidewalls created by offset laser cutting and an associated marker rivet secured therein, creating an increased overhanging effect and improved retention.

[0044] Figure 12D is a cross-sectional view of an assembled strut according to the present invention defining an eyelet having tapered or angled sidewalls with stepped or staggered layers and an associated marker rivet secured therein, creating an increased overhanging effect and improved retention;

[0045] Figure 12E is a cross-sectional view of an assembled strut according to the present invention defining an eyelet having a single chamfer along its outermost / top surface and an associated marker rivet secured therein, creating an overhanging effect and improved retention;

[0046] Figure 12F is a cross-sectional view of an assembled stay defining a bore having a double chamfer along its outermost / top surface and opposite innermost / bottom surface and an associated marker rivet secured therein, thereby improving retention without creating an overhang effect or increasing overall profile;

[0047] Figure 13A is a top view of an exemplary S-shaped bore defined in a single stay according to the present invention and a complementary S-shaped marker rivet secured therein;

[0048] Figure 13B is a top view of an exemplary single stay according to the present invention having a series of multiple bores each having an associated marker rivet secured therein, the marker rivets of the series being arranged non-linearly in tandem with one another when viewed from a side view, thereby creating the visual effect of a single continuous marker rivet rather than multiple independent marker rivets;

[0049] Figure 13C is a top view of an exemplary single stay according to the present invention having a series of multiple bores each having an associated marker rivet secured therein, the marker rivets being arranged linearly in tandem with one another when viewed from a side view (without overlap therebetween), thereby creating a more recognizable visual observation than would be created by a single marker rivet placed alone, and thus the particular series can be easily identified;

[0050] Figure 14A is a perspective view of a stay defining an angled recess on its outer periphery;

[0051] Figure 14B is a top view of the angled recess of the stay of Figure 14A ;

[0052] Figure 14C is a cross-sectional view of the angled recess of the stay of Figure 14A taken along line 14C-14C;

[0053] Figure 14D is a side view of the angled recess of the stay of Figure 14A ;

[0054] Figure 14E is a perspective view of an assembled stay having an angled recess defined on its outer periphery and a C-shaped or U-shaped marker secured therein; and

[0055] Figure 14F is a cross-sectional view of the assembled stay of Figure 14E taken along line 14F-14F showing that the C-shaped or U-shaped marker does not extend radially outward beyond the outer diameter of the stay after assembly. DETAILED DESCRIPTION

[0056] The terms "distal" or "proximal" are used in the following description in relation to position or orientation relative to a treating physician or medical interventionalist. "Distal" or "distally" is a position away from or in a direction away from the physician or interventionalist. "Proximal" or "proximally" or "proximate" is a position close to or in a direction toward the physician or medical interventionalist. The terms "occlusion", "clot" or "blockage" are used interchangeably.

[0057] Referring to Figure 2 , a radial cross-sectional view of an exemplary prior art drawn tube (DFT) composite wire 200 used to produce a mechanical thrombectomy device is shown. Figure 2 The wire in Figure 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 material with a high atomic number (e.g., atomic number in the seventies), such as platinum, gold, tantalum or tungsten. The second material comprising the outer layer 210 is a shape memory alloy such as nitinol (nickel-titanium metallic alloy). The shaped drawn composite tube made of the two different materials can then be cut radially inward, preferably using an ultra-high frequency laser, through the outer layer and the inner core to its center (rather than all the way through the wire). What is formed is a plurality of wedge-shaped or pie-shaped struts. In the exemplary embodiment of Figure 2 , five wedge-shaped or pie-shaped struts 205 are defined. Of course, the drawn tube wire can be laser cut as desired to define any number of one or more wedge-shaped or pie-shaped struts. In accordance with standard nitinol device production, each strut can be stretched over a mandrel and heat set.

[0058] From Figure 3 the single stretched strut 205 shown after polishing depicted can be seen clearly that each strut produced in accordance with the present application (all of the struts in the drawn tube wire) includes a segment or portion of the inner core 215 made of a radiopaque material (e.g., platinum in the exemplary embodiment shown). Since each strut includes some portion made of a radiopaque material, the entire or complete mechanical thrombectomy device is visible during diagnostic imaging.

[0059] As previously mentioned, the radiopacity, and thus the visibility, in the diagnostic imaging process of the mechanical thrombectomy device can be improved by attaching or affixing one or more markers made of a material having a higher radiopacity than the struts (e.g., gold, platinum or tantalum) to the struts of the stent. Figure 4A and 4BA plan view of a single eyelet or opening 400 of a strut of a prior art mechanical thrombectomy device (e.g., stent) and an associated or corresponding single rivet 405 (made of a radiopaque material) prior to the rivet being crimped within the eyelet (i.e., pre-riveting). Figure 4B A cross-sectional view of the eyelet and corresponding rivet along line 4B-4B is shown. This conventional shaped eyelet is elliptical or oval in shape and the associated marker rivet also has an elliptical, oval or rectangular cross-sectional profile Figure 4A ). After crimping (i.e., post-riveting), as shown in the plan view of Figure 4C , there is a certain distance (d, d’, d”) of contact or overlapping area between the crimped marker rivet and the eyelet. Figure 4D is a cross-sectional view taken along Figure 4C line 4D-4D of the eyelet and rivet (post-riveting).

[0060] To prevent the rivet marker from being dislodged from the opening or eyelet of the strut of the stent, the present invention increases the contact area and overlapping area, thus increasing the retention of the rivet in the strut eyelet. Unlike the conventional elliptical cross-sectional profile of the eyelet of prior art stents Figures 4A to 4D ) that do not have notches / recesses and / or protrusions / protuberances, Figures 5A to 5F the cross-sectional profile of the eyelet design of the present invention has one or more notches / recesses and / or protrusions / protuberances in its cross-sectional profile. Preferably, the cross-sectional profile of the eyelet design of the present invention has multiple notches / recesses and / or protrusions / protuberances. In the exemplary plan view of Figure 5A , the cross-sectional profile of the eyelet resembles a bow tie, rocket or cravat cross-sectional profile. This preferred geometric configuration of the eyelet preferably tapers from each of its respective sides towards the middle, i.e., the opposite sides pull inwards towards each other along line 5B-5B like a symmetrical mirror image. Relative to the conventional configuration (d, d’, d”) of a rectangular or elliptical eyelet Figure 4C , each notch or recess 510 of the eyelet 500 according to the present invention provides an increased or greater overlapping area or surface (D, D’, D”) where the overlapping area or surface represents the area that the rivet marker extends radially outwards from the outer profile of the eyelet after crimping (i.e., post-riveting). The contact area between the sidewall of the rivet and the sidewall of the eyelet is also increased due to the increased contact surface. This increase in overlapping area and contact surface improves the retention of the rivet marker 505 within the corresponding eyelet 500. The number, position and location of the notches or recesses 510 of the eyelet according to the present invention can be selected as desired to impart enhanced retention, preferably for those areas that are prone to the greatest bending, flexing and / or deformation during use.

[0061] As an alternative to riveting radiopaque markers into the defined eyelets in the struts of the stent, the radiopacity of the mechanical thrombectomy device can be improved by directly crimping the markers made of radiopaque material (e.g., gold or platinum) onto portions or segments of the strut itself. Unfortunately, such an approach results in an undesirably increased overall profile, i.e., an increased outer diameter (OD) and / or a decreased inner diameter (ID) of the crimped assembled device. With any increase in the overall profile of the marker, its leading edge can disadvantageously act as a hindrance point during loading or resheathing. To overcome these problems, the outer surface or profile of the superelastic alloy tube 600 (e.g., nitinol tube) according to the present application is treated to accommodate the forging or welding of the radiopaque markers thereon without increasing the overall profile of the assembled component. Specifically, prior to laser cutting the strut pattern, one or more annular recesses, grooves, or flutes 605 are defined radially inwardly by removing only a portion from the outer surface of the superelastic alloy original tube 600, as shown in Figure 6 It is noted that the annular recesses, grooves, or flutes do not penetrate the inner lumen 610. The one or more annular recesses, grooves, or flutes 605 can be machined by grinding, laser machining, or any other conventional technique to remove only a portion of the outer surface of the superelastic alloy tube material 610. A single annular recess, groove, or flute 605 (prior to being laser cut into the desired pattern and heated) is shown in a partial longitudinal view of the original superelastic alloy tube 600. Figure 6 However, as previously mentioned, any number of one or more annular recesses, grooves, or flutes 605 can be defined on the outer surface of the tube. The annular recesses, grooves, or flutes 605 are located at the positions where the desired radiopaque markers are to be positioned. The annular recesses, grooves, or flutes 605 have a radially inward depth "r" measured from the outermost perimeter of the tube to the opposing bottom surface of the annular recess, groove, or flute, which is typically about 10% to about 50% of the wall thickness. Preferably, the radially inward depth "r" is about 25 to 50 pm, sufficient to accommodate the U-shaped or C-shaped marker to be crimped therein, and the U-shaped or C-shaped marker does not extend radially outward beyond the outer diameter of the strut. Rather, the U-shaped or C-shaped marker is preferably flush with the outer diameter of the strut.

[0062] Once the material is removed from the outer surface of the superelastic alloy tube to form the one or more annular recesses, grooves, or flutes, the desired strut pattern can be laser cut on the machined tube so that the recesses can be aligned with the key strut locations of the device after the device is stretched. In Figure 7In an exemplary radial cross-sectional profile of, the super-elastic shape memory alloy tube has been laser cut to have a desired pattern of four struts (615a, 615b, 615c, 615d), each having an associated annular recess, groove, or channel (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, each having an associated annular recess, groove, or channel, can be formed as desired. A respective marker is forged or welded into the respective recess defined in the strut.

[0063] Figure 8 is a cross-sectional view of a single U-shaped or C-shaped marker 620 crimped within the annular recess, groove, or channel defined in strut 615c. Since the annular recess, groove, or channel is defined on the outer surface of the strut, the outermost perimeter of the U-shaped or C-shaped marker 620 does not extend radially outward beyond the outermost diameter of strut 615c. Thus, the overall profile of the assembled component is not increased (i.e., the outermost perimeter of the U-shaped or C-shaped marker is flush with or radially inward of the outer diameter (OD) of the strut), eliminating the potential for hooking.

[0064] Figures 14A to 14F An alternative configuration is shown in which an angled laser cut is made in the strut, removing a wedge-shaped or pie-shaped segment therefrom. Figure 14A is a perspective view of an exemplary strut 1400 having a pie-shaped or wedge-shaped recess 1405 formed by several angled laser cuts. Figure 14B and 14D show a top view and a side view, respectively, of Figure 14A a pie-shaped or wedge-shaped recess of a strut of. Figure 14C shows a partial cross-sectional view of a pie-shaped or wedge-shaped recess of a strut of Figure 14A along line 14C-14C. Once the angled laser cut(s) have been made to the strut, a C-shaped or U-shaped marker 1410 is then crimped, forged, or welded into the respective recess, as shown in Figure 14E a perspective view of an assembled device of. The angled laser cut(s) are made to the strut such that, when assembled, the marker does not extend radially outward beyond the outer diameter of the strut, as shown in Figure 14F . Preferably, the C-shaped or U-shaped marker is flush with the outer diameter of the strut.

[0065] Figure 9A and 9Bare plan 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 its proximal end, three radiopaque markers 910a, 910b, 910c at its opposite distal end, and four intermediate marker sets (915a, 915b, 915c, 915d) therebetween, with each intermediate marker set including four intermediate markers. Specifically, the first intermediate marker set 915a includes four intermediate marker segments (915al, 915a2, 915a3, 915a4), the second intermediate marker set 915b includes four intermediate marker segments (915bl, 915b2, 915b3, 915b4), the third intermediate marker set 915c includes four intermediate marker segments (915cl, 915c2, 915c3, 915c4), and the fourth intermediate marker set 915d includes four intermediate marker segments (915dl, 915d2, 915d3, 915d4). Any number of one or more radiopaque markers can be provided along the struts of the cage at the proximal end, the distal end, or intermediate locations therebetween.

[0066] Figure 10 is a perspective view of a portion of an exemplary cage 1000 in an expanded state showing struts or segments 1005 having four exemplary eyelet (1010a-d) locations for receiving therein associated rivets made of radiopaque marker material. The eyelets 1010a-d and thus the radiopaque marker rivets to be received therein are not radially aligned. Rather, the eyelets 1010a and 1010c are radially aligned, while 1010b and 1010d are staggered proximally or distally. The staggering of the eyelets and thus the radiopaque marker rivets therein makes them not radially aligned, thereby having the advantage of allowing the cage to be more effectively wrapped (collapsed) into a smaller diameter for loading into a catheter.

[0067] Figure 11A and 11B shows a laser cut pattern of an outer cage. Specifically, Figure 11A shows a portion of a flat, unfolded laser cut pattern for an outer cage 1100. As clearly seen in this figure, adjacent eyelets 1110a-e are offset or staggered relative to one another in the longitudinal or axial direction of the outer cage 1100. Specifically, eyelet 1110a is offset relative to 1110d. The staggering or offsetting of the eyelets facilitates effective packing of the outer cage in a compressed state with a relatively smaller profile, making it more suitable for receipt in a lumen defined on a microcatheter of a relatively smaller diameter. Figure 11BFIG. 1 1 shows a perspective view of a portion of the laser cut pattern of the outer cage 1 100 in a crimped configuration prior to expansion. Again, the staggered or offset arrangement of adjacent eyelets (1 1 10a-1 1 10e) relative to one another in the longitudinal or axial direction of the cage is apparent. Figure 11B

[0068] Each marker rivet is fixed in place within the associated eyelet defined on the strut to avoid displacement during the medical procedure. The marker is held in the eyelet sufficient to resist forces that would displace the rivet in a direction from the interior of the strut toward the exterior and from the exterior of the strut toward the interior. The overhang of the marker above the eyelet is a typical method for improving the fixation of the component, with the disadvantage of increasing the overall profile. Figure 12A Figure 12B is a cross-sectional view of a prior art assembly rivet 1210a within an associated eyelet 1200a having parallel sidewalls 1215a in this configuration, thus forming a rectangular or square wedge-shaped strut cross-section 1205a. In this design, the rivet has no overhang above the strut eyelet, and the angle of the sidewalls is minimal, if any, so the marker is prone to displacement from the eyelet during the medical procedure. It is also known in the prior art to allow the marker rivet 1210b to overhang at the top and bottom surfaces of the parallel sidewalls forming the eyelet 1200b, as shown in Figure 12C

[0069] Thus, it is desirable to develop a further enhanced design for securely holding the marker in the eyelet defined on the strut without the undesirable tradeoff of an increase in the overall profile that makes it difficult to wind the mechanical device during delivery through the microcatheter. The novel design according to the present invention has tapered or angled sidewalls 1215d of the eyelet 1200d further defined by multiple stepped or staggered tapered layers defined on the strut 1205d, which are further defined by the following: Figure 12D ​​​). Such steps or layers on tapered or angled sidewalls 1215d are advantageous because they can be created using standard laser settings by cutting a series of rings of decreasing diameter. This imparts the same beneficial effects as the design shown in Figure 12C but without the need for a laser cut center. In the cross-sectional view of Figure 12E and 12F the walls of the strut cross-section (1215e, 1215f) have a single chamfer (only at its outer / top surface) or a double chamfer (chamfered at both its outer / top surface and inner / bottom surface) defined on the strut, respectively. A chamfer is defined herein as an angled or beveled surface at the edge or corner of a strut sidewall. In one aspect, the single chamfer configuration creates an overhang effect only along the less important interior of the profile or volume, with no overhang profile on the outer / top surface. In another aspect, the double chamfer design provides enhanced retention without increasing the profile (along its outer / top surface or inner / bottom surface). The single or double chamfer configurations of Figure 12E can be formed using offset lasers.

[0070] Mechanical thrombectomy procedures are typically performed under fluoroscopic visualization, and radiopaque markers on mechanical thrombectomy devices provide the interventional physician with a visual indication of the position and expansion / pressing state of the device during the medical procedure. By way of illustrative example, information provided to the interventional physician during the medical procedure by the use of visual indications can include: the position of the device in the microcatheter at the time of delivery; the expansion of the device at the time of deployment; the change in expansion of the device at the time of retrieval.

[0071] Radiopaque markers arranged in clearly defined rings around the circumference at several locations along the mechanical device provide observable information to the physician or interventional physician during the medical procedure. Typically, the physician or interventional physician uses two fluoroscopic views during the procedure, an anterior-posterior view (parallel to the patient's torso) and a lateral view (parallel to the patient's side). It can be advantageous to distinguish the ring to which a particular identified marker belongs, and can pose a challenge to the physician or interventional physician.

[0072] The present invention seeks to improve the visibility of the markers and to distinguish the markers in each ring around the circumference by geometry, to easily recognize to which marker ring each individually identified marker belongs, enabling the physician or interventional physician to determine the expansion / pressing state of the device at discrete locations along the length of the device where the markers are located.

[0073] According to the present invention, the distinction or identification of the markers is achieved during the imaging process, without increasing the overall profile of the mechanical device or negatively affecting its performance (e.g., greater delivery force when advancing through the microcatheter). Figure 13AThe top view shows an S-shaped eyelet 1300a assembled on a strut 1305a, in which a complementary S-shaped mark 1310a is fixed. By changing the shape of the individual mark rivet, for example, making it longer, the rivet becomes more prominent and easier to see during imaging. Alternatively, without increasing the overall profile of the device, the visibility of the mark can be improved by a single crown or a single strut (defined as a segment between adjacent crowns) of a mechanical device having a series of multiple marks fixed within an associated eyelet, rather than a single mark fixed within a single eyelet. Figure 13B This is a top view of an exemplary single strut according to the invention, having a series of multiple eyelets, each eyelet holding an associated marking rivet. When viewed from various angles, the group of multiple marking rivets is more readily visible than a single marking rivet fixed to an associated single eyelet defined on a single strut. For example, when viewed from a partial side angle perspective view, the series of marking rivets on the single strut overlaps in series, creating the visual effect of a single, continuous marking rivet, rather than the visual effect of a series of multiple separate, different marking rivets using the same total volume of translucent material.

[0074] Figure 13C This is a top view of a single support bar according to an alternative exemplary embodiment of the invention, having a series of multiple eyelets arranged linearly, each eyelet holding an associated marking rivet. These groups of markings are more easily distinguishable than a single marking when viewed from different perspectives. For example, when viewed from an end view or a side view, the marking rivets are arranged in a linear series (without overlap) or other uniform configuration, thus producing a visually more easily distinguishable observation than that produced by a single marking rivet in a single eyelet defined on a single support bar. Figures 13A to 13C Such novel features can be used at any desired strut location (e.g., edge or perimeter) for easy identification and visibility during imaging. Despite the fact... Figure 13B and 13C Each group shown contains three markers, but any number of two or more markers can be used in the series as needed.

[0075] The features of the invention illustrated and described can be used in mechanical thrombectomy procedures, but are also applicable to other neurovascular or endovascular medical procedures.

[0076] Thus, although there have been shown, described and pointed out fundamental novel features of the application as applied to the preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in the form of the detail of

[0077] Each published patent, pending patent application, publication, journal article, book, or any other reference cited herein is each hereby incorporated by reference in its entirety.

Claims

1. An expandable mechanical device for use during a vascular medical procedure, the device comprising: a strut having an outer surface and an outer diameter radial profile, a recess defined on the outer surface of the strut and extending radially inward, wherein the recess is formed into only a portion of the outer surface of the strut; and a U-shaped marker rivet received and secured within the recess of the strut, the overall radial profile of the assembly of the strut and the U-shaped marker rivet being equal to or less than the outer diameter radial profile of only the strut.

2. The expandable mechanical device of claim 1, wherein the recess is an annular groove or an angled recess having a wedge-shaped radial cross-sectional profile.

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