Patent Publication Number: US-11642145-B2

Title: Guidewire with an atraumatic clot-circumventing configured distal end for use in an endovascular medical system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. patent application Ser. No. 16/003,527, filed Jun. 8, 2018, which is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an endovascular medical system advanceable through a vasculature with a distal end configured to minimize trauma to the vasculature tissue and branch vessels. In particular, the present invention is directed to a guidewire used to recanalize an occluded cerebral artery following an acute ischemic stroke, wherein the guidewire incorporates an atraumatic clot-circumventing configured distal end. 
     Description of Related Art 
     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 liberated from another part of the body which travels through the vessel and eventually become lodged in the cerebral artery of the brain. Clots are subject to a pulsatile pressure gradient (i.e., systemic blood pressure acting on the proximal thrombus face minus the pressure from retrograde collateral blood flow at the distal thrombus face) which may compact and further wedge in place the clot within the vessel over time. In addition, some degree of biological adhesion may occur between the clot and the interior wall of the vessel. 
     A procedure known as a thrombectomy may be used to remove the thrombus, occlusion, blockage or clot lodged in the vessel using a mechanical device. Thrombectomy treatment or procedure is typically performed on patients within a relative short period of time following a stroke (e.g., less than an approximately 48-hour period after the occurrence of a stroke) and is best suited for large vessel occlusions typically with a diameter greater than approximately 1.0 mm. Non-invasive imaging, for example, angiography, mostly CT angiography (CTA), is typically used to determine the clot size to determine if thrombectomy treatment is suitable for that particular patient. 
     During the thrombectomy procedure or treatment a physician or interventionalist endovascularly introduces a guidewire through the vasculature, typically in an artery located in the groin or by direct access through the carotid artery. The guidewire is advanced through the vasculature to a location facing a proximal side of the targeted clot, blockage or occlusion. Once the guidewire is properly positioned, a microcatheter with an outer diameter typically less than approximately 1.0 mm, tracks over the guidewire passing through a lumen defined axially through the microcatheter. 
     Guidewires commonly used for these types of procedures are relatively small in diameter so that they may easily pass through a lumen having a relatively small inner diameter defining a lumen extending longitudinally through the microcatheter. Conventional guidewire outer diameter sizes range from approximately 0.010″ to approximately 0.014″, while the inner diameter range of the lumen of the microcatheter is between approximately 0.016″ and approximately 0.027″. Typically, the outer diameter of the guidewire used is 0.014″, while the inner diameter of the microcatheter is 0.021″. Smaller size guidewires having an approximately 0.010″ outer diameter and microcatheters having an inner diameter lumen of approximately 0.016″ are sometimes used, particularly in smaller or more distal vessels. 
     Some physicians or interventionalists prefer to advance only the microcatheter across, around or over the clot, while retaining the guidewire distal end or tip within the lumen of the microcatheter on a proximal side facing the clot. That is, the distal end or tip of the guidewire never crosses over or around the clot to its distal side. The rationale being that the relatively soft and relatively flexible distal end of the microcatheter is less traumatic to the vasculature tissue than that of the guidewire. In many cases, due to its flexibility, it is very difficult to advance the microcatheter across, around or over the clot without the aid of the guidewire. To overcome such difficulty, the microcatheter and guidewire may be advanced across the clot together with the distal end or tip of the guidewire positioned inside the distal section of the microcatheter. 
     Otherwise, the guidewire may be advanced forward across the clot first and then followed by the microcatheter. Referring to  FIG.  1   , when advanced across the occlusion or clot  3  first, the guidewire  30  may undesirably: (i) enter a perforator vessel  17  that branches from a target, main or primary artery  15  potentially causing vessel damage and perforation; and/or (ii) cause injury or damage to the vessel tissue when passed across the clot. To minimize or prevent injury to the target vessel tissue and/or perforator vessels, when the guidewire is advanced across the clot prior to the microcatheter, the physician or interventionalist may deliberately change or alter the guidewire by bending its distal end or tip  1500  into a curved “J-shape”, as depicted in  FIGS.  15 A- 15 C , to assist in steering or guiding the microcatheter to its target location or site. The J-shaped distal end or tip  1500  includes a curved section  1505  (forming a curve less than 180°) which terminates in a free terminating end  1510 .  FIG.  15 B  depicts the prior art J-shaped distal tip  1500  of the guidewire approaching the clot  3 . As the guidewire is pushed forward by the physician the J-shape distal end or tip may deliberately prolapse (i.e., fold in on or over itself) while subject to resistance (e.g. friction) when passing between the inner vessel wall and the clot. In such prolapse configuration, the curved or loop section  1505  passes over the clot or occlusion  3  first thereby prohibiting the free terminating end  1510  from entering the perforator vessel  17  and damaging the vessel tissue. Prolapsing of the J-shaped distal tip only occurs upon being advanced forward against a resistance (e.g., when crossing over the clot between the vessel wall and the clot). That is, the J-shaped distal end or tip is not prolapsed while in a relaxed state (not subject to application of any external mechanical force, friction or resistance). However, shaping or altering of the distal tip or end of the guidewire in such manner is difficult to control by the physician or interventionalist possibly resulting in the shaped or altered distal end or tip being incapable of passing across or around the clot and/or potentially causing deleterious injury or damage to the target vessel tissue when passed (or attempted to be passed) across or around the clot. 
     The present invention overcomes the aforementioned problems associated with guidewires used in mechanical thrombectomy procedures by configuring an atraumatic clot-circumventing configured distal tip or end of the guidewire to prohibit advancement into one of the perforator vessels, yet easily pass over, across or around an occlusion between the occlusion and the inner wall of the target vessel, without penetrating the occlusion or without injuring the delicate tissue of the target neurovascular vessels. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention is directed to an improved guidewire for use in an endovascular medical procedure (e.g., mechanical thrombectomy) by configuring the distal tip or end of the guidewire to prohibit advancement into a perforator vessel, yet readily pass over, across or around an occlusion between the occlusion and the inner wall of the target vessel without injuring the tissue of the target neurovascular vessels. 
     Another aspect of the present invention relates an endovascular medical system for use with a clot located in a target vessel. The system including a guidewire formed by a core wire. The guidewire extending in a longitudinal direction from a proximal end to an opposite atraumatic clot-circumventing configured distal end; and a lateral direction of the atraumatic clot-circumventing configured distal end of the guidewire being defined transverse to the longitudinal direction of the guidewire. The atraumatic clot-circumventing configured distal end is designed to prevent injury to an inner wall of the target vessel and prohibit insertion of any portion of the guidewire into a perforator vessel. 
     Yet another aspect of the present invention is directed to a method for using an endovascular medical system for use with a clot located in a target vessel. The endovascular medical system including a microcatheter having a lumen defined longitudinally therethrough from its proximal end to its opposite distal end, wherein the lumen has an inner diameter. In addition, the endovascular medical system further includes a guidewire formed by a core wire and receivable through the lumen of the microcatheter. The guidewire extends in a longitudinal direction from a proximal end to an opposite atraumatic clot-circumventing configured distal end; a lateral direction of the atraumatic clot-circumventing configured distal end of the guidewire being defined transverse to the longitudinal direction of the guidewire. In accordance with the present invention, the atraumatic clot-circumventing configured distal end is configured to prevent injury to an inner wall of the target vessel and prohibit insertion of any portion of the guidewire into a perforator vessel. The method for using the present inventive system includes advancing the atraumatic clot-circumventing configured distal end of the guidewire through the target vessel to a location facing a proximal side of the clot. Then the microcatheter is tracked over the guidewire received within the lumen of the microcatheter to the location facing the proximal side of the clot. The atraumatic clot-circumventing configured distal end of the guidewire passes between the inner wall of the target vessel and the clot from a position on the proximal side of the clot to a position facing a distal side of the clot, without any portion of the atraumatic clot-circumventing configured distal end of the guidewire penetrating the clot. Thereafter, the microcatheter is guided over the guidewire received within the lumen of the microcatheter to the position facing the distal side of the clot. The microcatheter may also be used to provide support for the introduction of a distal access, guide or intermediate catheter. Now, the guidewire may be removed and a mechanical thrombectomy device such as a stentriever or any other clot retrieval device may be advanced through the microcatheter to the target site of the blockage and used to retrieve the clot or occlusion to the guide catheter or sheath. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The foregoing and other features of the present invention will be more readily apparent from the following detailed description and drawings of illustrative of the invention wherein like reference numbers refer to similar elements throughout the several views and in which: 
         FIG.  1    is an exemplary prior art conventional mechanical thrombectomy system including a guidewire having a conventional distal tip or end undesirably introduced into a perforator vessel after crossing through a clot, occlusion or blockage; 
         FIG.  2 A  is an exemplary illustration of a guidewire having an atraumatic clot-circumventing configured distal tip or end in accordance with the present invention, wherein the atraumatic clot-circumventing configured distal tip or end is the core wire bent into a lemon-shape configuration with a central opening or eyelet; wherein the guidewire in  FIG.  2 A  is illustrated in a relaxed or non-compressed state (not subject to application of an external mechanical force); 
         FIG.  2 B  is a cross-sectional view of the atraumatic clot-circumventing configured distal tip or end of the guidewire in  FIG.  2 A  along lines  2 B- 2 B; 
         FIG.  3 A  is another exemplary illustration of an atraumatic clot-circumventing configured distal tip or end of the guidewire in accordance with the present invention, wherein the atraumatic clot-circumventing configured distal end or tip is the core wire bent into a shepherd&#39;s crook shape configuration; wherein the guidewire in  FIG.  3 A  is illustrated in a relaxed or non-compressed state (not subject to application of an external mechanical force); 
         FIG.  3 B  is a cross-sectional view of the atraumatic clot-circumventing configured distal tip or end of the guidewire in  FIG.  3 A  along lines  3 B- 3 B; 
         FIG.  4    is an exemplary illustration of the present inventive mechanical thrombectomy system wherein the atraumatic clot-circumventing configured distal tip of the guidewire of  FIG.  2 A  is advanced through a target vessel over a blockage between the target vessel wall and the blockage, wherein the atraumatic clot-circumventing configured distal tip or end of the guidewire is prohibited from entering a perforator vessel after passing over or around the clot; 
         FIG.  5 A  is still another exemplary illustration of the atraumatic clot-circumventing configured distal tip or end of a guidewire in accordance with the invention, wherein the atraumatic clot-circumventing configured distal tip or end of the guidewire is a flattened portion of the core wire cut or stamped into a paddle shape; the paddle shaped distal tip or end is illustrated in  FIG.  5 A  in a relaxed or non-compressed state (not subject to application of an external mechanical force); 
         FIG.  5 B  is a cross-sectional view of the paddle shaped atraumatic clot-circumventing configured distal tip or end of the guidewire in  FIG.  5 A  along lines  5 B- 5 B; 
         FIG.  6    depicts the paddle shaped atraumatic clot-circumventing configured distal end or tip of the guidewire of  FIG.  5 A  while in a relaxed or non-compressed state (not subject to application of an external mechanical force) and a microcatheter guided over the guidewire which is received in the lumen of the microcatheter; 
         FIG.  7    depicts the paddle shaped atraumatic clot-circumventing configured distal end or tip of the guidewire of  FIG.  5 A  in a compressed state (i.e., subject to an applied external mechanical force exerted by the inner wall of the lumen of the microcatheter) when the guidewire is retracted or drawn back through the microcatheter; opposing lateral edges of the paddle shaped atraumatic clot-circumventing configured distal end or tip are wrapped, curled or rolled towards one another thereby reducing its diameter to be receivable within the inner diameter of the lumen of the microcatheter; 
         FIGS.  8 A- 8 C  illustrate the paddle shaped atraumatic clot-circumventing configured distal end or tip of the guidewire of  FIG.  5 A  as it advances over, around or across a clot between the inner wall of the target vessel and the clot, wherein the paddle shaped atraumatic clot-circumventing configured distal end or tip of the guidewire conforms in shape complementary to that of the inner wall of the target vessel; 
         FIG.  9    is a cross-sectional view of the vessel along lines  9 - 9  of  FIG.  8 B  illustrating how the paddle shaped atraumatic clot-circumventing configured distal end or tip of the guidewire of  FIG.  5 A  conforms to the shape of the inner wall of the vessel; 
         FIG.  10 A  is one exemplary configuration of the flattened paddle shaped atraumatic clot-circumventing configured distal tip or end of the core wire of the guidewire while in a relaxed or non-compressed state (not subject to application of an external mechanical force); 
         FIG.  10 B  is a cross-sectional view of the flattened paddle shaped atraumatic clot-circumventing configured distal tip or end of the guidewire in  FIG.  10 A  along lines  10 B- 10 B; 
         FIG.  11 A  is another exemplary configuration of the flattened paddle shaped atraumatic clot-circumventing configured distal tip or end of the core wire of the guidewire with a single central portion removed defining an eyelet or opening having a closed perimeter; wherein the flattened paddle shaped atraumatic clot-circumventing configured distal tip or end of the core wire of the guidewire is in a relaxed or non-compressed state (not subject to application of an external mechanical force); 
         FIG.  11 B  is a cross-sectional view of the flattened paddle shaped atraumatic clot-circumventing configured distal tip or end of the guidewire in  FIG.  11 A  along lines  11 B- 11 B; 
         FIG.  12 A  is still another exemplary configuration of the flattened paddle shaped atraumatic clot-circumventing configured distal tip or end of the core wire of the guidewire with multiple portions removed defining plural openings each of which has a closed perimeter; wherein the flattened paddle shaped atraumatic clot-circumventing configured distal tip or end of the core wire of the guidewire is in a relaxed or non-compressed state (not subject to application of an external mechanical force); 
         FIG.  12 B  is a cross-sectional view of the flattened paddle shaped atraumatic clot-circumventing configured distal tip or end of the guidewire in  FIG.  12 A  along lines  12 B- 12 B; 
         FIG.  13    is a partial cross-sectional view of the guidewire core having one or more coils disposed about its outer surface; 
         FIG.  14    is a partial cross-sectional view of the guidewire core covered by a polymer jacket, coating or outer layer; 
         FIG.  15 A  is a partial perspective view of a Prior Art J-shaped tip of a guidewire; 
         FIG.  15 B  depicts the Prior Art J-shaped tip guidewire of  FIG.  15 A  as it approaches a clot (on the proximal side of the clot); and 
         FIG.  15 C  depicts the Prior Art J-shaped tip guidewire of  FIG.  15 A  prolapsing as it crosses over the clot so that the curved loop section crosses the clot first, rather than the free terminating end. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The terms “distal” or “proximal” are used in the following description with respect to a position or direction relative to the treating physician or medical interventionalist. “Distal” or “distally” are a position distant from or in a direction away from the physician or interventionalist. “Proximal” or “proximally” or “proximate” are a position near or in a direction toward the physician or medical interventionist. The terms “occlusion”, “clot” or “blockage” are used interchangeably. 
     As illustrated in  FIG.  4   , the present inventive mechanical thrombectomy system  5  includes a microcatheter  10  having a lumen  25  defined in a longitudinal direction therethrough from its distal end  20  to its opposite proximal end. Microcatheter  10  may itself be received or advanced through a lumen  25 ′ defined longitudinally through a distal access, intermediate or guide catheter  10 ′. A guidewire  30  formed by a core wire has a distal end or tip  40  and an opposite proximal end defining a longitudinal direction therebetween. A lateral direction being defined transverse to the longitudinal direction of the guidewire. In accordance with the present invention, distal end or tip  40  of the guidewire  30  has an atraumatic clot-circumventing configuration. In accordance with the present invention, the term “atraumatic clot-circumventing configuration” can be any geometric shape and preferably satisfies the following three conditions. The first condition being that the atraumatic clot-circumventing configured distal end of the guidewire, while in a relaxed or non-compressed state, has a widest transverse width in a lateral direction (i.e., transverse to the longitudinal direction extending from the proximal end to the distal end of the guidewire) greater than the inner diameter of the lumen of the microcatheter through which the guidewire is received. Preferably, the widest transverse width is approximately twice the inner diameter of the microcatheter. Therefore, the preferred range of the widest transverse width is approximately 0.030″-approximately 0.050″ for a microcatheter having an inner diameter of 0.021″. This enlarged widest traverse width of the distal end or tip of the guidewire prohibits its insertion into a perforator vessel and thus, prevents injury or damage to the vessel tissue therein. A second condition being that the atraumatic clot-circumventing configured distal end of the guidewire is conformable in a lateral direction to complement the contour of the inner wall of the target vessel. Thus, when guidewire is advanced through the target vessel across, around or over the blockage passing between the inner wall of the target vessel and the blockage, no portion of the blockage is penetrated by the guidewire and the guidewire is atraumatic (not causing injury or damage) to the target vessel wall. The third condition to be satisfied by the atraumatic clot-circumventing configured distal end of the guidewire being that its widest traverse width in the lateral direction, when subject to application of an external mechanical force, is reducible in diameter to fit within the lumen of the microcatheter. 
     The atraumatic clot-circumventing configured distal end or tip  40  of the guidewire  30  may be pre-shaped by the physician or interventionalist or pre-formed. A non-super elastic material (i.e., a shaped memory alloy material that fails to meet the definition of a super elastic shape memory material provided below) may be used allowing the physician or interventionalist to pre-shape the distal end or tip of the core wire proximal to its atraumatic distal tip. Otherwise, a core wire made of a super elastic shaped memory material (i.e., a shaped memory alloy material that is reversibly deformable to very high strains (up to approximately 10%)) such as nitinol (NiTi) may be pre-formed, for example, by heat-setting during the manufacturing process. The entire guidewire may comprise this super elastic material as its core wire making it more durable, and thus suitable for re-use if multiple passes across the occlusion, clot or blockage are required. 
     Numerous variations or configurations of the present inventive atraumatic clot-circumventing configured distal end or tip  40  of the guidewire  30  are contemplated. Several illustrative examples are shown in the drawings and described in detail below. Other configurations are possible and thus the present invention is not to be limited only to those examples shown and described. 
       FIG.  2 A  in an enlarged partial view of an exemplary pre-formed atraumatic clot-circumventing configured distal end or tip  40  of the guidewire  30  in  FIG.  4   , while in a relaxed or non-compressed state (i.e., not subject to application of an external mechanical force). In this exemplary embodiment, the atraumatic clot-circumventing configured distal end or tip  40  of the core wire of the guidewire is pre-formed into a configuration resembling a lemon-shape forming a closed loop. A single eyelet or opening  45  is defined in the atraumatic clot-circumventing configured distal end or tip  40 . Depicted in  FIG.  2 B , is a cross-sectional view along lines  2 B- 2 B of  FIG.  2 A  through the widest traverse width in a lateral direction of the pre-formed core wire. 
     An enlarged partial view of another exemplary atraumatic clot-circumventing configured distal end or tip  40 ′ in which the core wire  30 ′ is pre-shaped into an open loop configured as a hook or shepherd&#39;s crook is depicted in  FIGS.  3 A &amp;  3 B . When forming the pre-shaped hook or shepherd&#39;s crook atraumatic clot-circumventing configured distal end or tip  40 ′ of the guidewire, the free terminating end  41  extends in a direction back towards the proximal end of the guidewire to form a curved open loop section that is greater than 180° (while in a relaxed, non-compressed state not subject to application of an external mechanical force). This configuration prohibits any portion of the atraumatic clot-circumventing configured distal end of the guidewire from entering the perforator vessel. In addition, the present inventive tip of the core wire bent backwards (i.e., prolapsed) towards the proximal end forming a curved open loop section greater than 180 degrees provides a curved surface rather than a single point (as with the blunt tip end of the conventional guidewire illustrated in  FIG.  1   ). The surface of the pre-shaped distal end is atraumatic preventing injury to the target vessel tissue while ensuring that the guidewire passes between the occlusion and inner wall of the target vessel, rather than penetrating the occlusion itself. 
     In the embodiment illustrated in  FIG.  3 A , the physician or interventionalist grasps the free terminating end  41  and straightens the pre-shaped hook or shepherd&#39;s crook distal end or tip prior to insertion of the free terminating end  41  into the lumen  25  at the proximal end of the microcatheter  10 . The distal end or tip of the guidewire maintains its straightened configuration or state while being advanced through the lumen of the microcatheter. Upon exiting from the distal end of the microcatheter, the distal end  40 ′ of the guidewire automatically reverts to its original curved pre-shaped hook or shepherd&#39;s crook configuration, as depicted in  FIG.  3 A  (relaxed or non-compressed state not subject to application of an external mechanical force). 
     Rather than pre-forming or pre-shaping the core wire to form a desired geometric shape as depicted in  FIGS.  2 A &amp;  3 A , a distal portion of the core wire (having a circular lateral cross-section) may alternatively be flattened out and then cut or stamped into a desired geometric shape to form the atraumatic clot-circumventing configured distal end or tip. In the exemplary embodiment shown in  FIG.  5 A , hereinafter referred to as a “planar paddle shape”  40 ″, the core wire is flattened so that it is substantially planar and its thickness reduced relative to the circular diameter of that remaining portion (non-flattened out portion) of the core wire. Once flattened out to a desired thickness, the planar distal end or tip is then cut or stamped into a desired shape (e.g., paddle shape) to form a thin support structure or substrate  50 , typically having a thickness ranging from approximately 0.0005″ to approximately 0.010″, preferably the thickness ranges from approximately 0.001″ to approximately 0.005″. The paddle shape distal end or tip may alternatively be achieved by assembling a pre-formed planar paddle shaped distal end or tip, having the same specified thickness range, on an end of a separate core wire, such as by welding, soldering or bonding. Two separate components assembled or joined together is particularly well suited to applications in which the pre-formed planar paddle and core wire on which the paddle is to be assembled are made of different materials. As illustrated in the cross-sectional view in  FIG.  5 B , an outer covering or layer  55  may be applied to the external surface of the supporting structure  50 . Outer covering or layer  55  may comprise one or more coverings, coating layers, or films. For instance, the outer covering or layer  55  may comprise a polymer jacket applied directly to the outer surface of the support structure or substrate  50  with or without a lubricious coating, e.g., a hydrophilic material, applied directly to the outer surface of the polymer jacket. The outer jacket may also contain radiopaque fillers to enhance fluoroscopic visibility of the tip. 
     The planar paddle shaped distal end or tip  40 ″ may have an asymmetrical design along its longitudinal axis  60  ( FIG.  6   ) extending in a direction from a proximal end to a distal end of the guidewire. Such asymmetrical design aids wrapping, curling, or rolling of the opposing lateral edges of the paddle shaped distal end or tip towards one another into a tube or cylinder as the guidewire is retracted backwards through the lumen  25  of the microcatheter  10 . As a result, the guidewire may be retracted or drawn back through the distal end of the microcatheter with minimal force. This wrapping, curling or rolling of the lateral edges of the planar paddle shaped distal end or tip  40 ″ within the lumen of the microcatheter is akin to that of rolling one&#39;s tongue.  FIG.  7    is a partial view illustration of the planar paddle shaped distal end or tip  40 ″ retracted or drawn back into the lumen of the microcatheter through its distal end  20  causing the lateral edges of the paddle to wrap, curl or roll towards one another. When wrapped, curled or rolled towards one another, the opposing lateral edges may, but need not necessarily, physically contact one another. Moreover, it is contemplated and within the intended scope of the present invention for the lateral edges to overlap one another when wrapped curled or rolled which beneficially allows a wider width paddle to fit within the lumen of the microcatheter. Upon exiting from the lumen  25  of the microcatheter  10 , the paddle shaped distal end or tip  40 ″ of the guidewire is automatically restored to its former planar relaxed or non-compressed state (not subject to application of an external mechanical force) (as depicted in  FIG.  5 A ). 
     The paddle is sized such that, while in its relaxed or uncompressed state (not subject to an applied external mechanical force) as depicted in  FIGS.  5 A &amp;  6   , its widest transverse width (WW) along a lateral direction  65  (transverse to that of the longitudinal direction  60  from the proximal end to the distal end of the guidewire) is greater than an inner diameter (ID) of the lumen  25  of the microcatheter  10  and wider than the diameter of the perforator vessels that the paddle is intended to prevent the guidewire from entering. The maximum widest transverse width is approximately twice the inner diameter of the microcatheter. For example, a paddle having a widest transverse width (WW) while in a relaxed or non-compressed state is preferably in the range of approximately 0.030″ to approximately 0.050″ for a microcatheter having an inner diameter of approximately 0.021″. 
     The paddle shaped distal end is also sufficiently flexible, based on the material used and its flattened thickness, so that when the guidewire is retracted or drawn back through the microcatheter the smaller inner diameter (ID) of the lumen applies an external mechanical force on the paddle shaped distal end causing it to curl and reduce in diameter smaller than the inner diameter of the lumen. Despite being larger in size, the paddle while in this compressed state can pass easily through the lumen  25  of the microcatheter  10 , as represented in  FIG.  7   . In this compressed state, the widest diameter (WD) of the wrapped, curled or rolled paddle shaped distal end is slightly smaller than the inner diameter (ID) of the lumen  25  of the microcatheter  10 . 
     The flattened distal end of the core wire, after having been cut, stamped or assembled into its paddle shape ( FIGS.  10 A &amp;  10 B ), may be further modified by removing (e.g., cutting or stamping) material within the flattened paddle shaped form. Removal of such material from the flattened paddle shaped distal end or tip advantageously: (i) increases flexibility so that the distal end or tip of the guidewire is able to more easily navigate between the clot and inner wall of the target vessel while also minimizing the force necessary to retract or draw back the paddle shaped distal end or tip through the lumen of the microcatheter; and (ii) is better suited to integrate a polymer jacket or other outer covering, layer or film over the flattened paddle shaped distal end or tip. A single central portion may be removed from the flattened paddle shaped distal end tip. In the example illustrated in  FIGS.  11 A &amp;  11 B , a single eyelet or opening  45 ′ conforming in shape to that of the outer perimeter of the paddle. It is noted that the opening  45 ′ need not be centrally located nor conform to the shape of the paddle. Another example is shown in  FIGS.  12 A &amp;  12 B , wherein material is removed from within the paddle form in more than one region defining four openings  45 ″. The paddle may be designed, as desired, to have any number of one or more openings, each of which may, but is not required, to conform in shape with the other openings and/or with that of the outer contour of the paddle. 
       FIGS.  8 A- 8 C  are partial illustrations of the flattened paddle shaped distal end guidewire of  FIG.  5 A  as it passes across the clot or occlusion  3  lodged in the vessel. As is depicted in the cross-sectional view of  FIG.  9   , the flattened paddle shaped distal end  40 ″ of the guidewire passes over or around the clot  3  at the interface between the clot and the inner wall of the target vessel without penetrating any portion of the clot. Since the paddle shaped distal end forms a surface rather than a point, the guidewire can easily navigate between the inner wall of the target vessel and the clot without injury to the tissue of the target vessel. Moreover, the enlarged width of the paddle while in a relaxed or non-compressed state (not subject to application of an external mechanical force) ensures that the guidewire after passing across, over or around the clot will not enter a perforator vessel. The paddle shaped distal end of the guidewire, as shown in  FIG.  9   , easily adapts to conform in shape to the inner wall of the vessel. This ability may reduce the force required to cross over or around the clot and more easily cross over or around more challenging fibrin rich or dense clots. 
     To aid visibility the core wire of the guidewire may be covered with a radiopaque material visible under imaging (e.g., under fluoroscopy). For example, a polymer jacket or outer covering  70  containing a radiopaque additive or filler may be applied directly to the outer surface of the guidewire  30  ( FIG.  14   ) and/or outer coils  75  (e.g., made of platinum alloy or other radiopaque material) wound about the outer surface of the guidewire  30 , as illustrated in  FIG.  13   . 
     In operation, such as during a thrombectomy procedure or treatment, a physician or interventionalist endovascularly introduces into a target vessel, typically in an artery located in the groin, a guidewire having an atraumatic clot-circumventing configured distal end or tip in accordance with the present invention. The guidewire is advanced through the vasculature to a location facing a proximal side of the targeted clot, blockage or occlusion. Once the guidewire is properly positioned, a microcatheter tracks over the guidewire passing through a lumen defined axially through the microcatheter. The present inventive atraumatic clot-circumventing configured distal tip of the guidewire is advanced across the clot first and then followed by the microcatheter. Because of the present inventive atraumatic clot-circumventing configured and sized distal end or tip, the guidewire easily passes around or over the clot without injury to the neurovasculature tissue of the target vessel, yet prevents the guidewire from entering a perforator vessel upon reaching the distal side of the clot. Once the distal end of the guidewire is properly positioned on the distal side of the clot, the microcatheter tracks over the guidewire crossing around or over the clot to its distal side. With the microcatheter positioned on the distal side of the clot, the guidewire may be retracted or withdrawn proximally backwards through the microcatheter, while the microcatheter remains in place. The microcatheter can also be used to provide support for the introduction of a distal access, guide or intermediate catheter. A mechanical thrombectomy device such as a stentriever or any other clot retrieval device can be advanced through the microcatheter to the target site of the blockage and used to retrieve the clot or occlusion to the guide catheter or sheath. 
     The present inventive guidewire has been illustrated and described for use in a mechanical thrombectomy procedure but is applicable for use in all neurovascular or endovascular medical procedures that employ guidewires. 
     Thus, while there have been shown, described, and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions, substitutions, and changes in the form and details of the systems/devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, it is expressly intended that all combinations of those elements and/or steps that perform substantially the same function, in substantially the same way, to achieve the same results be within the scope of the invention. Substitutions of elements from one described embodiment to another are also fully intended and contemplated. It is also to be understood that the drawings are not necessarily drawn to scale, but that they are merely conceptual in nature. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto. 
     Every issued patent, pending patent application, publication, journal article, book or any other reference cited herein is each incorporated by reference in their entirety.