Abstract:
Distal access aspiration guide catheter system and methods for delivering implantable devices, catheters, or substances in or near and/or restoring flow through body lumens, such as blood vessel lumens are described. A distal access aspiration guide catheter having a proximal, medial, and distal possessing high flexibility, high resistance to kinking and a large lumen to wall thickness ratio.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims the benefit of priority to U.S. Provisional Application Ser. No. 61/503,546, filed on Jun. 30, 2011, the entire contents of which are incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates generally to medical devices and methods and more particularly to catheter-based systems and methods useable for accessing, diagnosing, or treating defects in blood vessels, such as blood vessels of the brain. 
         [0004]    2. Background of the Related Art 
         [0005]    Stroke is a common cause of death and disability. In the United States, approximately 700,000 patients suffer from stroke annually. Stroke is a syndrome characterized by the acute onset of a neurological deficit that persists for at least 24 hours, reflecting focal involvement of the central nervous system, and is the result of a disturbance of the cerebral circulation. Its incidence increases with age. Risk factors for stroke include systolic or diastolic hypertension, hypercholesterolemia, cigarette smoking, heavy alcohol consumption, and oral contraceptive use. 
         [0006]    Hemorrhagic stroke accounts for 20% of the annual stroke population. Hemorrhagic stroke often occurs due to rupture of an aneurysm or arteriovenous malformation (AVM), causing bleeding into the brain tissue and resultant infarction of brain tissue. The remaining 80% of strokes are due to ischemia that occurs due to occlusion of a blood vessel that deprives brain tissue of oxygen-carrying blood. Ischemic strokes are often caused by emboli or pieces of thrombotic tissue that have dislodged and traveled from other body sites, or from the cerebral vessels themselves, to occlude in the narrow cerebral arteries more distally. When a patient presents with neurological symptoms and signs, which resolve completely within 1 hour, the term transient ischemic attack (TIA) is used. Etiologically, TIA, and ischemic stroke share the same pathophysiologic mechanisms and thus represent a continuum based on persistence of symptoms and extent of ischemic insult. 
         [0007]    Emboli occasionally form around the valves of the heart or in the left atrial appendage during periods of irregular heart rhythm and then are dislodged and follow the blood flow into the distal regions of the body. Those emboli can pass to the brain and cause an embolic stroke. As will be discussed below, many such occlusions occur in the middle cerebral artery (MCA), although such is not the only site where emboli come to rest. 
         [0008]    When a patient presents with neurological deficit, a diagnostic hypothesis for the cause of stroke can be generated based on the patient&#39;s history, a review of stroke risk factors, and a neurologic examination. If an ischemic event is suspected, a clinician can tentatively assess whether the patient has a cardiogenic source of emboli, large artery extracranial or intracranial disease, small artery intraparenchymal disease, or a hematologic or other systemic disorder. A head CT scan is often performed to determine whether the patient has suffered an ischemic or hemorrhagic insult. Blood would be present on the CT scan in subarachnoid hemorrhage, intraparenchymal hematoma, or intraventricular hemorrhage. 
         [0009]    To reach these lesions or occlusions microcatheter and microguidewire must be employed, but often the column support of these microcatheters is not strong enough to navigate through the distal reaches of the neurovasculature to effectively treat these sites. Often guide catheters are employed to act as a conduit to help support microcatheter access. Traditional guide catheters designed for coronary or peripheral use (U.S. Pat. No. 5,180,376 &amp; U.S. Pat. No. 5,484,425 Fischell, U.S. Pat. No. 5,045,072 Castillo, U.S. Pat. No. 5,279,596 Castaneda, U.S. Pat. No. 5,454,795 Samson and U.S. Pat. No. 5,733,400 Gold), typically are not positioned above the skull base and limit their effectiveness in supporting microcatheters in the distal cerebrovasculature. Newer distal access guide catheters have been developed which are slightly longer, thinner, a bit more flexible than the early generations, but are constructed with the same manufacturing techniques as described in U.S. Pat. No. 5,180,376 &amp; U.S. Pat. No. 5,484,425 Fischell, U.S. Pat. No. 5,045,072 Castillo, U.S. Pat. No. 5,279,596 Castaneda, U.S. Pat. No. 5,454,795 Samson and U.S. Pat. No. 5,733,400 Gold, but have not solved the kinking problem (e.g., Neuron Penumbra Recall—Oct. 2, 2009). 
       SUMMARY 
       [0010]    This description may use the phrases “in an embodiment,” “in embodiments,” “in some embodiments,” or “in other embodiments,” which may each refer to one or more of the same or different embodiments in accordance with the present disclosure. For the purposes of this description, a phrase in the form “A/B” means A or B. For the purposes of the description, a phrase in the form “A and/or B” means “(A), (B), or (A and B)”. For the purposes of this description, a phrase in the form “at least one of A, B, or C” means “(A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C)”. 
         [0011]    As used herein, the terms proximal and distal refer to a direction or a position along a longitudinal axis of a catheter or medical instrument. The term “proximal” refers to the end of the catheter or medical instrument closer to the operator, while the term “distal” refers to the end of the catheter or medical instrument closer to the patient. For example, a first point is proximal to a second point if it is closer to the operator end of the catheter or medical instrument than the second point. The measurement term “French”, abbreviated Fr or F, is defined as three times the diameter of a device as measured in mm. Thus, a 3 mm diameter catheter is 9 French in diameter. The term “operator” refers to any medical professional (i.e., doctor, surgeon, nurse, or the like) performing a medical procedure involving the use of aspects of the present disclosure described herein. 
         [0012]    In an aspect of the present disclosure, a catheter device for accessing, diagnosing, or treating defects in blood vessels, such as blood vessels of the brain is provided. The catheter device includes a tubular member having an inner lumen and an outer surface that includes a metallic structure having spaces defined therein and a polymeric material disposed within the spaces. An inner liner extends through the lumen of the tubular member and defines an inner lumen of the catheter. There is an outer covering on the outer surface of the tubular member. The polymeric material disposed within the spaces is different from the materials of the inner liner and outer cover. 
         [0013]    In another aspect of the present disclosure, a guide catheter section is provided that includes an elongate tubular catheter body having a proximal end and a distal end and a passageway defining an inner lumen extending between those ends. The elongate tubular catheter body includes an inner tubular liner of a first liner material in coaxial relationship with an outer tubular cover and a tubular member between the inner liner and outer cover. The tubular member includes a metallic structure and a polymeric kink resistance member, having the same handedness. The catheter section, in the region of the distal end, has a wall thickness to inner diameter ratio in excess of 16:1 and a lateral flexibility of greater than 1200°/in-lb, and ultimate tensile strength of greater than 15N&#39;s 
         [0014]    In yet another aspect of the present disclosure, a guide catheter includes an elongate tubular member having a proximal end and a distal end and a passageway defining an inner lumen extending between those ends. The elongate tubular member has a relatively stiff proximal segment that includes an inner proximal tubular liner having a proximal liner material in coaxial relationship with an outer proximal tubular cover having a proximal cover material. The proximal segment also includes a metallic braid structure braided upon said inner proximal tubular liner and covered by said outer proximal tubular cover. The elongate tubular member also includes a relatively flexible distal segment. The distal elongate tubular member includes an inner tubular liner of a first liner material in coaxial relationship with an outer tubular cover having a first cover material. The distal elongate tubular member also includes at least a metallic and a polymeric kink resistance member structure having the same handedness and both wound exterior to the inner tubular liner, and covered by said outer tubular cover. The catheter section, in the region of the distal end, having a wall thickness to inner diameter ratio in excess of 16:1 and a lateral flexibility of greater than 1200°/in-lb, and ultimate tensile strength of greater than 15N&#39;s. The elongate tubular member also includes at least one intermediate segment defining a passageway between the relatively stiff proximal segment and the relatively flexible distal segment with has a transition from the braided stiffening structure to the metallic and polymeric kink resistance member structure. 
         [0015]    In any or all of the aspects described above, the metallic structure may include a nickel titanium alloy such as a nickel titanium alloy ribbon. The metallic structure may be a metal helix having a helical gap where the helical gap is of continuous width or the dimension(s) of the metal helix and/or width of the helical gap varies. Alternatively, the metallic structure may be a metal braid having a number of pics where the number of pics per inch varies. 
         [0016]    The polymeric material may be a thermoset polymer, an elastomer, a cast elastomer, or a cast polyurethane. The cast polyurethane may include a thermoset polyurethane adhesive. The inner liner may include at least one material selected from the group consisting of: fluoropolymers; PTFE; PFA and FEP. The outer cover may include at least one material selected from the group consisting of: polyesters and polyolefins. 
         [0017]    The catheter device may have a plurality of regions along its length wherein dimension(s) of the metal helix and/or the width of the helical gap differ between said regions. Alternatively, the catheter device may have a plurality of regions along its length wherein dimension(s) the number of pits per inch differ between said regions. Such regions may include a proximal region, a medial region and a distal region. 
         [0018]    The outer cover on the proximal region may have a polyester having a thickness of about 0.001 inch, the outer cover on the medial region may have polyester having a thickness of about 0.0005 inch, and the outer over on the distal region may have polyolefin having a thickness of about 0.0005 inch. 
         [0019]    The distal region has a lateral flexibility of greater than 1200°/in-lb and a kink radius of about 0.174 inch+/−0.008 inch or less. 
         [0020]    In other aspects, the catheter device may also include a balloon where the balloon is a compliant balloon. 
         [0021]    In a further aspect of the present disclosure, a method for treating or diagnosing a disorder in a human or animal subject is provided that includes inserting into the subject&#39;s vasculature any of the catheter devices described herein. After inserting the catheter device, a substance or device is delivered through the lumen of the catheter device and the substance or device is used to treat or diagnose the disorder. 
         [0022]    The catheter may be advanced into a blood vessel located within the subject&#39;s skull. The blood vessel into which the catheter device is advanced is selected from the group consisting of: carotid artery, cerebral artery, anterior cerebral artery, middle cerebral artery and posterior cerebral artery. 
         [0023]    In yet another aspect of the present disclosure, a method for manufacturing a catheter is provided. The method includes forming or obtaining a metallic structure having spaces defined therein and causing polymeric material to be disposed within the spaces such that the polymeric material and the metallic structure, in combination, form a tubular member having an outer surface and a lumen. An inner liner is disposed within the lumen of the tubular member and an outer cover is disposed on the outer surface of the tubular member. 
         [0024]    The inner liner may be disposed on a mandrel and the metallic structure is then positioned on top of the inner liner. The metallic structure may include a nickel titanium alloy disposed about the inner liner and then heat set. A flowable polymer mixture is cast into the spaces and allowed to solidify, thereby forming the tubular member with the inner liner disposed therein. The polymer may be a polymer adhesive such as a thermoset polymer. 
         [0025]    A release agent or barrier is applied to one or more selected areas of the metallic structure to deter or interrupt adhesion of the polymer adhesive to the selected areas of the metal helix. The polymer adhesive causes adhesion between the tubular member and the inner liner. 
         [0026]    The method also includes causing a quantity of polymer adhesive to be disposed between the outer surface of the tubular member and the inner surface of the outer cover to cause adhesion between the tubular member and the outer cover. 
         [0027]    The outer cover comprises a tube that initially has an inner diameter that is larger than the outer diameter of the tubular member and wherein the outer cover is advanced over the tubular member and contacts the tubular member to cause a snug fit on the outer surface of the tubular member. The outer cover is heat shrunk onto the outer surface of the tubular member. A radiographic marker may be disposed on or in the catheter device. In addition, a hydrophilic coating may be applied to an outer surface of the outer cover. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The above and other aspects, features, and advantages of the present disclosure will become more apparent in light of the following detailed description when taken in conjunction with the accompanying drawings in which: 
           [0029]      FIG. 1A  illustrates a side view of one embodiment of a catheter according to an embodiment of the present disclosure; 
           [0030]      FIG. 1B  illustrates a cross-sectional view of the catheter taken along the line  1 B- 1 B of  FIG. 1 ; 
           [0031]      FIG. 1C  illustrates a cross-sectional view of the catheter taken along the line  1 C- 1 C of  FIG. 1 ; 
           [0032]      FIG. 1D  illustrates a detailed view of the area outlined in  FIG. 1 ; 
           [0033]      FIG. 2A  illustrates a cross-sectional view of the catheter taken along the line  2 A- 2 A of  FIG. 1   
           [0034]      FIG. 2B  illustrates a detailed view of an area outlined in  FIG. 2A ; 
           [0035]      FIG. 2C  illustrates a detailed view of an area outlined in  FIG. 2A ; 
           [0036]      FIG. 3A  illustrates a side view of a liner and reinforcement layer assembly of the catheter illustrated in  FIG. 1 ; 
           [0037]      FIG. 3B  illustrates a side view of the proximal, medial, and distal coils according to an embodiment of the present disclosure; 
           [0038]      FIG. 3C  illustrates a side view of the proximal, medial, and distal braids according to another embodiment of the present disclosure; 
           [0039]      FIG. 4  illustrates a side view of a first adhesive layer arrangement of the catheter illustrated in  FIG. 1 ; 
           [0040]      FIG. 5  illustrates a side view of a second adhesive layer and cover arrangement of the catheter illustrated in  FIG. 1 ; 
           [0041]      FIG. 6  illustrates a side view of a coated catheter; and 
           [0042]      FIG. 7  illustrates a side view of a catheter according to another embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0043]    Particular embodiments of the present disclosure are described hereinbelow with reference to the accompanying drawings; however, the disclosed embodiments are merely examples of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. Like reference numerals may refer to similar or identical elements throughout the description of the figures. 
         [0044]    There is provided in accordance with one aspect of the present disclosure, a method for accessing regions of the vasculature through tortuous anatomy. Such vasculature includes the cerebrovasculature wherein access to the Circle of Willis and beyond is exceedingly difficult due to the carotid siphon or vertebral artery anatomy that must be traversed to reach such locations without undo trauma or vessel straightening. The method comprises the steps of providing a catheter having a proximal end and a distal end. The distal end of the catheter is inserted into the artery, and the support is distally advanced. Negative pressure can be applied to the proximal end of the catheter, or an affixed aspiration port, to draw the thromboembolic material into the distal section. Catheters and other instrumentation (working devices) can be inserted through the distal access aspiration guide catheter within the vasculature to gain access to locations where flexibility, kink resistance, torqueability, and column strength are required. 
         [0045]    Typical arteries may be, among other examples, the common carotid artery, the internal carotid artery, the carotid siphon, the Circle of Willis, etc. Alternatively, the artery may be the middle cerebral artery or the anterior cerebral artery, or elsewhere in the brain. 
         [0046]    The method may additionally comprise the steps of introducing oxygenated medium into the artery through the aspiration lumen, or infusing pharmaceutical agent into the artery through the aspiration lumen. The pharmaceutical agent may be a vasodilator such as nifedipine or nitroprusside. The pharmaceutical agent may alternatively comprise t-PA. The thromboembolic material may be located using intravascular ultrasound, or carotid Doppler imaging techniques. 
         [0047]    In accordance with another aspect of the present disclosure, there is provided an intracranial aspiration catheter. In accordance with the present disclosure, there is provided a method of establishing a flow path through a catheter, positioned across a non-linear segment of vasculature. 
         [0048]    In certain embodiments, the aspiration catheter can serve as a guide catheter for placement of the micro-catheter. The guide catheter is advanced to a target region in cooperation with a guidewire to allow for steering and manipulation through the vasculature. In an exemplary procedure, the guidewire and guide catheter are introduced into the vasculature at a site within a femoral or iliac artery. Using a Seldinger technique, or other percutaneous procedure, a hollow 18-Gauge needle can be introduced into a femoral artery via percutaneous procedure. A guidewire is next advanced through the hollow needle and into the arterial tree. The hollow needle is next removed and an introducer sheath is advanced into the arterial tree. The guide catheter is next advanced through the catheter introducer either through the same guidewire or through a larger guidewire suitable for aortic traverse. The guide catheter is advanced through the aortic arch, into a carotid artery, through the carotid siphon and into a region proximate the circle of Willis. The guide catheter, because of its flexibility and high kink resistance can easily inserted through tortuous anatomy beyond the carotid siphon or the vertebral and basilar arteries. Once properly placed, the guide catheter can be utilized as a large conduit for the insertion of other working devices. Because of its large inner diameter multiple devices can be inserted. The guide catheter can serve as an aspiration device and as a shield for retrieval of debris, thrombus, or other material from the vasculature. 
         [0049]    The guide catheter is terminated, at its proximal end, with a luer or hemostasis valve and optionally with a connector offering multiple access ports, each of which can be valved or be terminated with a stopcock, etc. 
         [0050]    There is disclosed a distal access aspiration catheter  100  in accordance with one aspect of the present disclosure. Although primarily described in the context of distal access aspiration guide catheter with a single central lumen, catheters of the present disclosure can readily be modified to incorporate additional structures, such as permanent or removable column strength enhancing mandrels, two or more lumens to permit drug or irrigant infusion or radiation delivery or to supply inflation media to an inflatable balloon, or combinations of these features, as will be readily apparent to one of skill in the art in view of the disclosure herein. Further, catheters of the present disclosure may have a rapid exchange configuration. In addition, the present disclosure will be described primarily in the context of providing distal vascular access for other endovascular working devices and removing obstructive material from remote vasculature in the brain. 
         [0051]    The catheters disclosed herein may readily be adapted for use throughout the body wherever it may be desirable to introduce a very flexible thin walled catheter and kink resistant, which provides a relatively large diameter aspiration or supported working channel. For example, catheter shafts in accordance with the present disclosure may be dimensioned for use throughout the coronary and peripheral vasculature, the gastrointestinal tract, the urethra, ureters, Fallopian tubes and other lumens and potential lumens, as well. The lumen structure of the present disclosure may also be used as a minimally invasive percutaneous tissue tract expander, such as for diagnostic or therapeutic access to a solid tissue target (e.g., breast biopsy or tissue excision). 
         [0052]      FIGS. 1A-1D  illustrate a guide catheter  100  according to an embodiment of the present disclosure. In this example, the guide catheter  100  comprises an elongate body having a proximal section  101 , a medial section  102  and a distal section  103 . A lumen  104  extends through the catheter  100 . The elongate body of the catheter comprises an inner liner or sleeve  105 , and a kink resistant member  106 . A distal outer cover  108  is disposed on the distal section  103  and medial section  102  and a proximal tubular cover  109  is disposed on the proximal section  101 . A luer or manifold  110  is provided on the proximal end of the elongate catheter body. Optionally, one or more radiographic marker(s)  112  may be positioned on or in the elongate catheter body, such as at the distal tip as shown in the example of  FIGS. 1A and 1D . 
         [0053]    The polymers comprising the proximal tubular cover  109  and the distal tubular cover  109  are heat set using heat shrink tubing or other compression methodology and heat, such as that generated by a heated air flow source, radiant heat source, induction heater, radiofrequency heater, or the like. Alternatively, the proximal tubular cover  109  and the distal tubular cover  109  may be set by overcoating the catheter by extrusion, dip coating, spray coating, vapor deposition, etc. 
         [0054]    The kink resistant member  106  includes metallic structures  206   a ,  206   b ,  206   c  ( FIG. 2A ) in the form of helical coil ( FIG. 3B ) or braid ( FIG. 3C ). With a helical coil, the winds (i.e., helical convolutions) of metallic structures  206   a ,  206   b ,  206   c  are disposed such that distributed flexibility can be generated along the lengths of the catheter shaft. With a braid, the pics are disposed such that distributed flexibility can be generated along the lengths of the catheter shaft. The metal used in metallic structures  206   a ,  206   b ,  206   c  can be nitinol, stainless steel, cobalt-nickel alloy, titanium, or the like. Metallic structures  206   a ,  206   b ,  206   c  may be faulted by winding one or more wires to form a helical coil or a braid. The wires may have a flat-wire cross-section, a circular cross-section, or any other polygonal cross-section. Alternatively, in other embodiments, metallic structures  206   a ,  206   b ,  206   c  may be formed from a metallic tube that is laser cut, chemically etched, or grinded to form a desired pattern for metallic structures  206   a ,  206   b ,  206   c . In another embodiment, metallic structures  206   a ,  206   b ,  206   c  may be built upon a removable substrate by electrodeposition, vapor deposition, sintering, or any other processes that may be used to build metallic structures  206   a ,  206   b ,  206   c  on a removable substrate. 
         [0055]    The gap within the metallic winds of the helical coil or pics in the braid are filled with polymeric kink resistant members  207   a  and  207   b , which can cause the flexibility to be substantially evenly distributed, or directed along a specific axis. The polymeric kink resistant member  207  may be a thermoset polymer (e.g., thermoset urethane), thermoplastic, or the like. Additionally, polymeric kink resistant members  207   a  and  207   b  may be a polymer that is firmed up by solvent evaporation, cross linking, or a room-temperature vulcanized (RTV) polymer. Moreover, metallic structures  206   a ,  206   b ,  206   c  may be overcoated by extrusion, dip coated, spray coated, vapor deposition, etc. 
         [0056]    The kink resistant member  106  can beneficially be created such that the reinforcement becomes more flexible moving distally by changing the gap or thicknesses of metallic structures  206   a ,  206   b ,  206   c  and/or polymeric kink resistant members  207   a  and  207   b . Additionally the flexibility can also be adjusted be changing the thicknesses and materials of the inner sleeve  105  and/or outer tubular covers  108  and/or  109 . 
         [0057]    The proximal end of the catheter is additionally provided with luer or a manifold  110  having one or more access ports as is known in the art. Generally, the manifold is provided with a guidewire port in an over-the-wire construction, an aspiration port, and a catheter insertion port. One or more of these features can be embodied within a single port. Alternatively, the aspiration port may be omitted if the procedure involves removal of the guidewire proximally from the guidewire port following placement of the aspiration catheter, and aspiration through the guidewire port. Additional access ports may be provided as needed, depending upon the functional capabilities of the catheter. The manifold may be injection molded from any of a variety of medical grade plastics, or formed in accordance with other techniques known in the art. 
         [0058]    The proximal body segment will exhibit sufficient column strength to permit axial positioning of the catheter through a patient&#39;s vasculature. The catheter body may further comprise other components, such as radiopaque fillers; colorants; reinforcing materials; reinforcement layers, such as braids and helical reinforcement elements; or the like. In particular, the proximal body segment may be reinforced in order to enhance its column strength and torqueability while limiting its wall thickness and outside diameter. 
         [0059]    When present, an optional radiographic marker  112  will typically be provided at least at the distal end of the catheter  100 . Other radiopaque markers may be provided elsewhere, such as on the support coil, if it is not already radiopaque. One embodiment of a radiopaque marker that may be used comprises a metal band, which is fully recessed within the distal end of the proximal body segment. Suitable marker bands can be produced from a variety of materials, including platinum, gold, and tungsten/rhenium alloy. The radiopaque metal band may be recessed in an annular channel formed at the distal end of the proximal body segment. 
         [0060]    Diameters outside of the preferred ranges may also be used, provided that the functional consequences of the diameter are acceptable for the intended purpose of the catheter. For example, the lower limit of the diameter for any portion of tubular body in a given application will be a function of the number of fluid or other functional lumen contained in the catheter, together with the acceptable minimum aspiration flow rate and collapse resistance. 
         [0061]    Tubular catheter body must have sufficient structural integrity (e.g., column strength or “pushability”) to permit the catheter to be advanced to distal locations without buckling or undesirable bending of the tubular body. The ability of the body to transmit torque may also be desirable, such as to avoid kinking upon rotation, to assist in steering. The tubular catheter body, and particularly the distal section, may be provided with any of a variety of torque and/or column strength enhancing structures. For example, axially extending stiffening wires, spiral wrapped support layers, braid(s) or woven reinforcement filaments may be built into or layered on all or part of the tubular catheter body. 
         [0062]    In many applications, the proximal section will not be required to traverse particularly low profile or tortuous arteries. For coronary vascular applications, for example, the proximal section will be mostly or entirely within the relatively large diameter guide catheter. The transition can be located on the catheter shaft to correspond approximately with the distal end of the guide catheter when the balloon and/or distal end is/are at the treatment site. For certain other applications, such as intracranial catheterizations, the distal section is at least about 5 cm long and small enough in diameter to pass through vessels as small as 3 mm or 2 mm or smaller. Catheters for this application may have a proximal section length of between about 60 cm to about 150 cm and a distal section length of between about 5 cm to about 15 cm, and the distal section is able to track a tortuous path of at least about 5 cm through vessels of less than about 3 mm lumen ID. 
         [0063]    The number of catheter body sections may vary. For example, distal section  103  may comprise a first distal section and a second distal section. The dimensions (e.g., width, thickness) of the metal structure  206  and/or the outer cover  108  may vary between the two distal sections, thereby causing them to have different properties. 
         [0064]    Table 1 below shows examples of inner diameter to wall thickness ratios for catheters of the present disclosure in sizes ranging from 4 French to 8 French. In some embodiments, the inside diameter (ID) to wall thickness or wall section can include ratios from about 16:1 to about 24:1. 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                   
                   
                 Preferred Wall 
                   
               
               
                 Catheter Size 
                 Wall Thickness 
                 Thickness 
                 Inside Diameter (ID) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 8 French 
                 0.0045″-0.0055″ 
                 0.005″ 
                 0.094″-0.096″ 
               
               
                 7 French 
                 0.004″-0.005″ 
                 0.0045″ 
                 0.082″-0.084″ 
               
               
                 6 French 
                 0.003″-0.004″ 
                 0.0035″ 
                 0.072″-0.073″ 
               
               
                 5 French 
                  0.003″-0.0035″ 
                 0.00325″ 
                 0.059″-0.060″ 
               
               
                 4 French 
                 0.0025″-0.003″  
                 0.00275″ 
                 0.046″-0.047″ 
               
               
                   
               
             
          
         
       
     
         [0065]    In an 8 French catheter, the wall thickness can range from about 0.0045 to 0.0055 inches, with a preferred wall thickness of about 0.005 inches and the inside diameter of the catheter can preferably range from about 0.094 inches to about 0.096 inches. 
         [0066]    In a 7 French catheter, the wall thickness can range from about 0.004 to 0.005 inches, with a preferred wall thickness of about 0.0045 inches and the inside diameter of the catheter can preferably range from about 0.082 inches to about 0.084 inches. 
         [0067]    In a 6 French catheter, the wall thickness can range from about 0.003 to 0.004 inches, with a preferred wall thickness of about 0.0035 inches and the inside diameter of the catheter can preferably range from about 0.072 inches to about 0.073 inches. 
         [0068]    In a 5 French catheter, the wall thickness can range from about 0.003 to 0.0035 inches, with a preferred wall thickness of about 0.00325 inches and the inside diameter of the catheter can preferably range from about 0.059 inches to about 0.060 inches. 
         [0069]    In a 4 French catheter, the wall thickness can range from about 0.0025 to 0.003 inches, with a preferred wall thickness of about 0.00275 inches and the inside diameter of the catheter can preferably range from about 0.046 inches to about 0.047 inches. 
         [0070]      FIGS. 2A-2C  illustrate cross-sectional views of a catheter  100  in accordance with an embodiment of the present disclosure. As shown in  FIGS. 2A-2C , a lumen  104  is defined by inner line  105 . Metallic structure  206   a  is disposed on the inner line  105  in proximal section  101 , metallic structure  206   b  is disposed on the inner liner  105  in medial section  102 , and metallic structure  206   c  is disposed on the inner liner  105  in distal section  103 . Metallic structures  206   a ,  206   b , and  206   c  may be composed of a single wire or multiple wires. A first polymeric kink resistant member  207   a  is disposed between the spaces in metallic structure  206   a  while a second polymeric kink resistant member  207   b  is disposed between the spaces in metallic structures  206   b  and  206   c . An adhesive  207   c  is disposed over the radiographic marker  112  to form a tip. A polymeric layer  210  is also disposed over the distal end of metallic structure  206   a . The outer cover of the catheter  100  includes a proximal tubular cover  209  disposed in proximal section  101 . The outer cover also includes a distal outer cover  208  that is disposed over distal section  103 , medial section  102  and a portion of proximal section  101 . 
         [0071]      FIGS. 3A-3C  illustrates a side view of an aspiration guide catheter subassembly  300  comprising a hub  302  and an inner liner  304 .  FIG. 3B  illustrates a plurality of coil windings  306 ,  308 ,  310 , detailing the catheter liner and coil subassembly arrangement.  FIG. 3C  illustrates a plurality of braided sections  406 ,  408 ,  410 . The subassembly  300  further comprises a strain relief  326 , an overall length  324 , a working length  322 , a PTFE liner length  314 , a distal section length  320 , a medial section length  318 , and a proximal section length  316 . 
         [0072]    Referring to  FIG. 3A , the inner liner  304  can comprise PTFE, PFA, FEP, or other lubricious polymer. The exterior diameter surface of the inner liner  304  can be etched to increase its roughness. Such etching can be performed using methodology including, but not limited to, plasma discharge treatment, mechanical abrasion, laser etching, and the like. The inner liner  304  is generally disposed over a removable mandrel of the appropriate diameter, said mandrel (not shown) comprising a metallic core and an exterior lubricious coating such as PTFE, FEP, PFA, Parylene, or the like. The hub  302  can be fabricated from a variety of polymers selected from materials including, but not limited to, polyethylene, polypropylene, acrylonitrile butadiene styrene (ABS), polysulfone, polycarbonate, polyvinyl chloride, polystyrene, polyester, and the like. The hub  302  can also be fabricated from metals such as, but not limited to, stainless steel, titanium, cobalt nickel alloy, and the like. The hub  302  comprises a through lumen (not shown) that can slidably accept devices up to the indicated size of the guide catheter subassembly  300 , namely about 4, 5, 6, 7, 8, and 9 French, for example. The hub  302  can comprise a strain relief in the region where it is affixed to the tubing of the guide catheter subassembly  300  to minimize kinking and transfer forces to the guide catheter subassembly  600  under maximum control. Attachment between the hub  302  and other components of the subassembly  300  can comprise ultraviolet (UV) light curing adhesive such as, but not limited to, Dymax™ 1128-M-VT UV curing adhesive, or the like. The attachment between the hub  302  and the other components of the catheter subassembly  300  can also comprise cyanoacrylate adhesive such as, but not limited to, Loctite  4011 , and the like. 
         [0073]    Referring to  FIG. 3B , the spacing on the distal coil  310  can be approximately 0.008, with a range of about 0.006 to 0.010 inches. The spacing on the medial coil  308  can be approximately 0.004 inches with a range of about 0.002 to 0.006 inches. The spacing on the proximal coil  306  can be approximately 0.001 inches with a range of about 0.0005 to 0.002 inches. The tighter the spacing of the coils  306 ,  308 ,  310  the stiffer the system and the greater the torque carrying capability of the system. Thus, the proximal coil  306  is stiffer than the medial coil  308 , which is, in turn, stiffer than the distal coil  310 . The coils  306 ,  308 ,  310  can be fabricated from nitinol with superelastic or pseudoelastic properties. The width of the individual turns in the coil can range in width from about 0.001 inches to about 0.010 inches and the thickness of the individual turns in the coil can range from about 0.0005 to about 0.005 inches. The coils  306 ,  308 ,  310  may have spring characteristics and is not malleable. The coils  306 ,  308 ,  310  can be fabricated from nitinol, as previously stated, but it can also be fabricated from materials such as, but not limited to, cobalt nickel alloy, titanium, stainless steel, polyester, polyethylene naphthalate, and the like. 
         [0074]    Referring to  FIG. 3C , the pics per inch (PPI) on the distal braid  410  can be approximately 20-50 PPI. The PPI on the medial braid  408  can be approximately 50-100 PPI. The PPI on the proximal braid  406  can be approximately 100-150 PPI. The smaller the PPI of the braids  406 ,  408 ,  410  the stiffer the system and the greater the torque carrying capability of the system. Thus, the proximal braid  406  is stiffer than the medial braid  408 , which is, in turn, stiffer than the distal braid  410 . The braids  406 ,  408 ,  410  can be fabricated from nitinol with superelastic or pseudoelastic properties. The thickness of the braid strands can range in width from about 0.001 inches to about 0.010 inches and the thickness of the braid strands can range from about 0.0005 to about 0.005 inches. The braids  406 ,  408 ,  410  may have spring characteristics and is not malleable. The braids  406 ,  408 ,  410  can be fabricated from nitinol, as previously stated, but it can also be fabricated from materials such as, but not limited to, cobalt nickel alloy, titanium, stainless steel, polyester, polyethylene naphthalate, and the like. 
         [0075]    Although,  FIG. 3B  describes the use of different coils in the proximal, medial, and distal sections of the guidewire and  FIG. 3C  describes the use of different braids in the proximal, medial, and distal sections of the guidewire, in some embodiments, different combinations of coils and braids can be used in the various sections to improve the torque and flexibility of the guidewire. 
         [0076]    The liner and coil subassembly  300  construction for a catheter having a working length  322  (catheter length exclusive of the hub, strain relief  326  or any other attachments) of 105-cm is as follows: The overall length  324  can be about 113-cm, the working or usable length  322  can be about 105-cm, the liner length  314  can be about 110-cm, the proximal coil length  316  can be about 96-cm, the medial coil length  318  can be about 6-cm, and the distal coil length  320  can be about 8-cm. 
         [0077]    The liner and coil subassembly  300  construction for a catheter having a working length  322  of 115-cm is as follows: The overall length  324  can be about 123-cm, the working or usable length  322  can be about 115-cm, the liner length  314  can be about 120-cm, the proximal coil length  316  can be about 106-cm, the medial coil length  318  can be about 6-cm, and the distal coil length  320  can be about 8-cm. 
         [0078]      FIG. 4  illustrates a side view of an aspiration guide catheter subassembly  500  comprising a plurality of first adhesive layers  502 ,  504  disposed over and between the coils  306 ,  308 ,  310  or braids  406 ,  408 ,  410  of the aspiration guide catheter subassembly  300 . 
         [0079]    Referring to  FIG. 4 , the first adhesive layer  502 , disposed over the proximal regions of the subassembly  500 , comprises materials such as, but not limited to, Flexobond 431™, supplied by Bacon Co., Irvine, Calif. The distal first adhesive layer  504 , disposed over the distal regions of the subassembly  500 , comprises materials such as, but not limited to, Flexobond 430™, supplied by Bacon Co., Irvine, Calif. The proximal first adhesive layer  502  can be configured to provide increased stiffness relative to that of the distal first adhesive layer  504 . The first adhesive layers  502 ,  504  generally are applied to the subassembly  500  along the entire length of the tubing  314  and the thickness of the layers  502 ,  504  is approximately equal to, or slightly greater than that of the coils  306 ,  308 ,  310  or braids  406 ,  408 ,  410 . 
         [0080]    In a subassembly  500  having a usable or working length of 105 cm, the length  512  of the proximal first layer of adhesive  502  can be about 93-cm, ranging from about 80-cm to about 100-cm. In a subassembly having a usable length of 115 cm, the length  512  of the proximal first layer of adhesive  502  can be about 103-cm, ranging from about 90-cm to about 110-cm. The length  514  of the first distal layer of adhesive  504  can range from about 10 to about 25-cm with a range of about 15 to about 10-cm and a more preferred value of about 17-cm. 
         [0081]      FIG. 5  illustrates a side view of an aspiration guide catheter subassembly  600  that comprises a plurality of second layers of adhesive proximal  602 , intermediate  604 , and distal  606 , a proximal outer layer of polymeric coating  608 , and a distal layer of outer polymeric coating  624 . The subassembly  600  further comprises at least one radiopaque marker band  610  and a transition ring of UV adhesive  618 . The proximal second layer of adhesive  602  has a length  612  while the distal second layer of adhesive  606  has a length  616  and the intermediate second layer of adhesive  604  has a length  614 . The catheter subassembly  600  further comprises an overlap region  620  disposed at the transition between the proximal second layer of adhesive and the intermediate second layer of adhesive  604 . The subassembly  600  further comprises an outer layer of polymeric shrink wrap tubing  622  in the intermediate region. 
         [0082]    Referring to  FIG. 5 , the distal second layer of adhesive  606  is disposed over the distal part of the catheter subassembly  600  as well as being disposed over the intermediate second layer of adhesive  604 . 
         [0083]    The proximal second layer of adhesive can have a length of about 91-cm (range about 80-cm to about 100-cm) for a catheter having a 105-cm working length and about 101-cm (range about 90-cm to about 110-cm) for a catheter having a 115-cm working length. The length of the intermediate second layer of elastomeric adhesive can be about 5.5-cm with a range of about 3-cm to about 7-cm. The length of the distal layer of elastomeric adhesive can range between about 15-cm and 25-cm with an exemplary value of about 19.5-cm for catheters having working lengths of about 105-cm to about 115-cm. The overlap region  620  can have a length of about 0.5-cm with a range of about 0.1-cm to about 1.0-cm. The length of the UV curable adhesive ring  618  can range from about 0.5-mm to about 2-mm with an exemplary value of about 1.0-mm. 
         [0084]    In an embodiment, the radiopaque marker band  610  can be fabricated from platinum iridium wire having a diameter of about 0.002 inches. Materials comprised by the radiopaque marker  610  can include platinum, platinum-iridium, gold, tantalum, barium sulfate, bismuth sulfate, and the like. The radiopaque marker  610  can comprise or be configured as a coil of round wire or flat wire, or it can be configured as an axially elongate cylindrical band, as a serpentine band of wire, or the like. The radiopaque marker  610  can comprise a length of about 0.5 mm to about 5-mm. The radiopaque marker  610  can be embedded within the elastomeric adhesives and be disposed between the innermost layer  304  and the outermost layer of polymer  608  and  624 . 
         [0085]    The outermost layers of polymer  608 ,  622 , and  624  can be fabricated from materials such as, but not limited to, polyester (PET), polyimide, Pebax™, polyamide, or the like. In some embodiments, the outermost layers of polymer  608  in the proximal region can be configured as heat shrink tubing having a thickness of about 0.001 inches. The outermost layer of polymer  624  in the distal region can comprise polyimide (Pebax™) heat shrink tubing having a thickness of between about 0.0005 and 0.002 inches. The distal outer second polymer layer can be sourced from Iridium corporation. The intermediate outer layer of polymer  622  can comprise polyester (PET) having a wall thickness of about 0.00025 inches, with a range of about 0.0001 to about 0.001 inches. 
         [0086]    The second layer of adhesive in the proximal region  602  may comprise Flexobond 431 but can also comprise other similar materials, such as but not limited to other 2-part urethane adhesives, 1-part urethane adhesive, or the like. The second layer of adhesive in the intermediate region  604  comprises Flexobond 430 but can also comprise other similar materials, such as but not limited to other 2-part urethane adhesives, 1-part urethane adhesive, or the like. The second layer of adhesive in the distal region  606  may comprise Flexobond 430 soft mix but other similar materials can also be used. 
         [0087]      FIG. 6  illustrates a side view of an aspiration guide catheter subassembly  700 . In catheter subassembly  700  an additional coating layer  702  may be applied to the distal end of catheter. Coating layer  702  may include coating base, a crosslinker A coating, and/or crosslinker B coating. 
         [0088]      FIG. 7  illustrates a guide catheter  800  according to another embodiment of the present disclosure. In this example, guide catheter  800  is similar to guide catheter  100  described above. Whereas guide catheter  100  has a straight configuration, guide catheter  800  has a modified J shape configuration. 
         [0089]    In some embodiments of the disclosure, an optional balloon, such as a compliant balloon formed of material such as latex, silicone, polyurethane, C-Flex™ thermoplastic elastomer, Chronoprene™, Santoprene™ or the like, may be positioned at or near the distal end of the elongate catheter body. Such optional balloon may be useful for occluding flow through the blood vessel in which the catheter is positioned when such flow occlusion is desired. 
         [0090]    In at least some embodiments, the proximal section  101  will retain radial strength but provide lateral flexibility. Additionally, that section desirably has a lateral flexibility (stiffness), such as would be measured by, for example, a Tinius-Olsen™ Stiffness Tester, of at least 1,200 degrees of deflection/inch-pound (measured at 20 degrees to 30 degrees of deflection, with a 0.005 lb load, over a 0.25″ span), preferably 2,500 degrees of deflection/inch-pound. The radial compression strength of the section is quite high as compared to other distal sections found on comparable catheter distal sections of prior art guide catheters. 
         [0091]    Access for the catheter of the present disclosure can be achieved using conventional techniques through an incision on a peripheral artery, such as right femoral artery, left femoral artery, right radial artery, left radial artery, right brachial artery, left brachial artery, right axillary artery, left axillary artery, right subclavian artery, or left subclavian artery. An incision can also be made on right carotid artery or left carotid artery in emergency situations. 
         [0092]    The construction disclosed herein is suitable for guide catheter as a stand-alone device. This construction results in a highly flexible device having high column strength, torqueability, superior kink-resistance unachievable in prior art devices having a thin wall tube of this size, and high tensile strength. 
         [0093]    It is to be appreciated that the disclosure has been described hereabove with reference to certain examples or embodiments of the disclosure but that various additions, deletions, alterations and modifications may be made to those examples and embodiments without departing from the intended spirit and scope of the disclosure. For example, any element or attribute of one embodiment or example may be incorporated into or used with another embodiment or example, unless otherwise specified of if to do so would render the embodiment or example unsuitable for its intended use. Also, where the steps of a method or process have been described or listed in a particular order, the order of such steps may be changed unless otherwise specified or unless doing so would render the method or process unworkable for its intended purpose. All reasonable additions, deletions, modifications and alterations are to be considered equivalents of the described examples and embodiments and are to be included within the scope of the following claims.