Abstract:
A catheter is provided for retrieving an embolus or foreign body from a body lumen. The catheter can have a distal segment which is movable from a reduced outside diameter for positioning at a target site. Further, the catheter can have an enlarged outside diameter suitable for thrombectomy or foreign body retrieval.

Description:
This application claims priority to U.S. Provisional Application 61/490,280 filed May 26, 2011. 
    
    
     FIELD OF THE INVENTION 
     The inventions described below relate the field of medical devices for percutaneously accessing and performing therapy on body lumens and cavities, and more particularly, to methods and devices for clot or debris removal within the cardiovascular system 
     BACKGROUND OF THE INVENTION 
     Stroke is the third most common cause of death in the United States and the most disabling neurologic disorder. 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. 
     Eighty percent strokes are ischemic strokes and are caused by occluded vessels that deprive the brain of oxygen-carrying blood (the remaining 20% of strokes are hemorrhagic strokes, which result in bleeding into the brain). Ischemic strokes are often caused by emboli or pieces of thrombotic tissue that have dislodged 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. 
     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. Many such occlusions occur in the middle cerebral artery (MCA), although such is not the only site where emboli come to rest. 
     Ischemic stroke is sometimes treated by injecting tissue plasminogen activator (t-PA) or Activase® into the patient&#39;s blood stream. However, treatment with systemic t-PA is associated with increased risk of intracerebral hemorrhage and other hemorrhagic complications. Patients treated with t-PA are more likely to sustain a symptomatic intracerebral hemorrhage during the first 36 hours of treatment. The frequency of symptomatic hemorrhage increases when t-PA is administered beyond 3 hours from the onset of a stroke. Besides the time constraint in using t-PA in acute ischemic stroke, other contraindications include the following: if the patient has had a previous stroke or serious head trauma in the preceding 3 months, if the patient has a systolic blood pressure above 185 mmHg or diastolic blood pressure above 110 mmHg, if the patient requires aggressive treatment to reduce the blood pressure to the specified limits, if the patient is taking anticoagulants or has a propensity to hemorrhage, and/or if the patient has had a recent invasive surgical procedure. Therefore, only a small percentage of selected stroke patients are qualified to receive t-PA. 
     Stroke is sometimes treated by attempting to re-establish blood flow in the blocked artery. Certain percutaneous methods have been utilized for reestablishing blood flow. A common percutaneous technique is referred to as balloon angioplasty where a balloon-tipped catheter is introduced to a blood vessel, advanced to the point of the occlusion and inflated in order to dilate the stenosis. Balloon angioplasty is appropriate for treating vessel stenosis but is not effective for treating acute thromboemboli. In patients with vertebral artery occlusions, treatment with angioplasty often results in disastrous complications due to embolization of the occlusive lesion downstream to the basilar artery. Emboli small enough to pass through the vertebral arteries into the larger basilar artery are usually arrested at the top of the basilar artery, where it bifurcates into the posterior cerebral arteries. The resulting reduction in blood flow to the ascending reticular formation of the midbrain and thalamus produces immediate loss of consciousness. 
     Another percutaneous technique is to place a microcatheter near the clot and infuse streptokinase, urokinase or other thrombolytic agents to dissolve the clot. Unfortunately, thrombolysis typically takes hours to days to be successful. Additionally, thrombolytic agents can cause severe hemorrhage and in many patients the agents cannot be used at all. 
     Another percutaneous technique is to place a guide catheter proximate the clot and aspirate the clot into the guide catheter. This procedure requires that the guide catheter be brought into close proximity of the clot in order to be effective. Proper placement may be difficult or impossible. Furthermore, a highly aggregated, cohesive clot may not easily be aspirated into a guide catheter without prior thrombolysis or breakdown into small pieces. 
     Yet another percutaneous technique is to place an expandable structure, located at or near the distal end of a catheter, through a vessel obstruction and expand that structure. The expandable structure can be used to pull the clot back into a guide catheter with its open end placed nearby. Activation of the expandable structure, however, using linkages or other mechanisms can be difficult to perform or control due to the high amount of friction present in a long cerebrovascular catheter with extremely small lumens. 
     Another problematic area is the removal of foreign bodies. Foreign bodies introduced into the circulation can be fragments of catheters, pacemaker electrodes, guide wires, and erroneously placed embolic material such as thrombogenic coils. The use of such removal devices is difficult and sometimes unsuccessful. 
     Thus, there exists a need for the development of a device that can be percutaneously introduced, endovascularly advanced to the target lesion, moved across or into the obstruction, and deployed in a controlled, reliable manner into the circulatory system for the removal of viscoelastic clots and foreign bodies without the risk of clot disgorgement, flaking, or incomplete removal. The system needs to, then, be retracted, along with the obstruction from the target vessel. There is also a need for a device, which could be used as a temporary arterial or venous filter to capture and remove thromboemboli formed during endovascular procedures. 
     SUMMARY OF THE INVENTIONS 
     The present inventions are directed to methods and devices for removing obstructions from blood vessels. The devices may be used to retrieve and remove clots and other biological obstructions. The device may also be used to retrieve embolic coils and the like which have been misplaced or have migrated to an undesirable location. 
     The laterally, radially, diametrically, or circumferentially expandable structure (hereinafter “expandable structure”) can be employed to secure the distal end of the therapeutic catheter to a specific location within a vessel. The expandable structure can also be used to generate a screen or net capable of preventing emboli from passing while still allowing for blood flow. The expandable structure can be used as a temporary stent to expand a stenosis within a vessel. The expandable structure can be used to create a temporary occlusion to a vessel. The expandable structure can be used as a flow modifier for an aneurysm or as a neck bridge. The expandable structure can be used as a localization device to temporarily secure another device in place within a vessel. The expandable structure can be used as a delivery system for thrombolytics, embolic materials, or implants. 
     The proximal end of the expandable structure can be affixed or integrally formed to a ring, tube, C-collar, or sleeve, which slidably moves forward or backward along the axis of the guide catheter. The expandable structure can comprise a mesh coupled to ring structures at the first end and the second end of the expandable structure. Further, the expandable structure can comprise a plurality of longitudinal struts that are connected to ring structures at the first end and the second end of the expandable structure. 
     The ring can be advanced distally, or moved proximally, by means of a linkage slidably disposed through one or more lumens in the catheter shaft and actuated at the proximal end of the catheter. The distal end of the linkage, which can be a wire, rod, tube, or other axially elongate structure, can be affixed to the ring and cause the ring to move proximally, distally, or both. A spring can be used to move the ring proximally or distally. For example, if the linkage is a polymer thread, having little column strength, the spring can cause the ring to move distally while the linkage can cause the ring to move proximally. The linkage can support tension but not compression. Some rods can support column strength and compression and, thus, can force the ring distally. 
     The ring can be affixed to a fluidic system that can be pressurized to move, or force, the ring forward toward the distal tip, or depressurized to create a vacuum, or remove incompressible fluid, and move the ring backward, away from the distal tip of the catheter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates a side view, in partial cross-section, of the distal end of a catheter, configured to be introduced through a guide catheter, comprising a radially expandable region near its distal end. 
         FIG. 1B  illustrates a side view, in partial cross-section, of the distal end of the catheter of  FIG. 1A  wherein the proximal end of the expandable region has been advanced distally by introduction of fluid into a plunger system. 
         FIG. 2  illustrates a side view, in partial cross-section, of the proximal end of a catheter, configured to be introduced through a guide catheter, comprising a central lumen and an inflation lumen. 
         FIG. 3A  illustrates a side exterior view of the distal end of a therapeutic catheter in its radially collapsed state. 
         FIG. 3B  illustrates a side exterior view of the distal end of the therapeutic catheter of  FIG. 3A  in its radially expanded state. 
         FIG. 4A  illustrates a side partial breakaway view of a therapeutic catheter in its first, unexpanded configuration, wherein an annular piston is affixed to the proximal end of the expandable element. 
         FIG. 4B  illustrates a side partial breakaway view of the therapeutic catheter of  FIG. 4A  in its second, expanded configuration, wherein the annular piston has advanced distally, moving the proximal end of the expandable structure distally to reduce its length and increase its diameter. 
         FIG. 5  illustrates a side partial breakaway view of the proximal end of the therapeutic catheter of  FIGS. 4A and 4B , according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The devices described herein can be used to remove thromboembolic material from the vertebral artery or other cerebrovascular vessel. The occlusion site can be first localized with transcranial Doppler and angiogram. The catheter can be inserted through an incision on a peripheral artery into the symptomatic vertebral artery or the subclavian artery. For example, the distal end of a guide catheter can be inserted proximal to thromboembolic material in right vertebral artery and left subclavian artery. The foreign body removal catheter can be advanced through the thromboembolic material so that it resides distal thereto. The expandable region is expanded using fluidic systems to a second, larger diameter. The expandable catheter is withdrawn proximally, pulling the thromboembolic material therewith and into the open distal end of the guide catheter. The thromboembolic material may thereafter be removed from the vessel, optionally with the assistance of continuous or pulsed suction, thereby reducing the risk of embolization to the basilar artery. 
     Access for the catheter of the present invention 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  130  in emergency situations. 
     The length of the catheter for those access sites to reach the brain will generally be between about 20 and 150 centimeters, preferably approximately between 60 and 130 centimeters. The inner diameter of the catheter may be between about 0.010 and 0.050 inches. 
       FIG. 1A  illustrates the distal end  100  of the catheter whose proximal end  100  is illustrated in  FIG. 1A . The distal end  100  comprises the catheter shaft  212 , the central lumen  206  and the pressurization lumen  210 . The distal end  100  further comprises an expandable mesh  102 , an activation bladder  106 , a pressure lumen plug  124 , a proximal bladder to catheter tubing weld  108 , and a distal bladder slider ring  104  separated from the catheter shaft  212  by a slider ring gap  116 . The distal end  100  yet further comprises the pressurization port  114  and the inner volume  110  of the bladder  106 . In the illustrated embodiment, the distal end  100  further comprises a return spring  118 . 
     Referring to  FIG. 1A , the distal bladder slider ring  104  is affixed to the distal end of the bladder  106 . The distal bladder slider ring  104  is also affixed to the proximal end of the expandable mesh or structure  102 . The ring  104  can be affixed to the bladder  106  by adhesives, heat welding, clamps, pins, or the like. The ring  104  can be heat welded, insert molded, mechanically attached, or otherwise affixed to the expandable structure  102 . The return spring  118  can be affixed to the ring  104  by welding, adhesives, mechanical fixation devices such as pins, screws, clamps, or the like. The return spring  118  can be fabricated from elastomeric materials having resistance to permanent deformation. Such elastomeric materials include polyurethane, Hytrel, silicone, stainless steel, nitinol, and the like. Metal springs can be formed as coils, serpentine, or other bent structures. Polymeric elastomers can be formed into threads, rods, sheets, or the like and simply stretch under the influence of the pressurized forcing of the ring  104  distally. During shipping and storage, the spring will be unstressed and, thus not eventually fail due to creep or material elongation during a long-term period of stretching. 
     The purpose of the pressure lumen plug  124  is to prevent leakage of pressurized fluid from the distal end of the pressure lumen  210  during pressurization to advance the ring  104  distally. In other embodiments, the pressure lumen  210  can be melted closed using heat, solvents, pressure, or other energy. The plug  124  is beneficial since it would be difficult and expensive to have the plug built into (integral to) the extrusion of the catheter tube  212 , although this alternative is certainly possible. 
       FIG. 1B  illustrates the distal end  100  wherein interior volume  110  of the bladder  106  has been pressurized with incompressible fluid through the lumen  210  and the port  114 . The distal end  100  comprises the catheter shaft  212 , the central lumen  206 , the pressurization lumen  210 , and the pressure lumen plug  124 . The distal end  100  further comprises the expandable mesh  102 , the activation bladder  106 , the proximal bladder to catheter tubing weld  108 , and the distal bladder slider ring  104  separated from the catheter shaft  212  by the slider ring gap  116 . The distal end  100  yet further comprises the pressurization port  114 , the inner volume  110  of the bladder  106 , and the return spring  118 . The system can also comprise an optional external sleeve  120  to prevent excessive diametric expansion of the bladder or bag  106 . Optionally, the inside of the slider ring  104  can comprise an affixed bushing, “O-rings”, or gasket  122 . 
     Referring to  FIG. 1B , pressurization of the volume  110  has caused the bladder  106  to expand in the only direction possible, distally. The distal ring or sliding seal  104  moves distally and the material making up the bladder  106  is substantially inelastic so the bladder  106  cannot increase in diameter under the applied pressure. Instead, the distal end of the bladder  106 , and its affixed ring  104 , slides distally by way of the small gap  116  between the ring  104  and the catheter tube  212 . The small gap  116  provides for low friction and is configured to seal against fluid loss from the internal volume  110 . The ring  104  performs the function of a bushing or bearing with close tolerances to the catheter shaft  212 . An optional, leak-proof gasket or bushing  122  can be disposed in the space  116  (see  FIG. 1A ), affixed to the interior of the ring  104 , to prevent fluid or pressure leakage from the internal region  110  of the bag  106 . 
       FIG. 2  illustrates the proximal end  200 , in partial breakaway cross-section, of a catheter configured to expand at its distal end, the proximal end  200  comprising a hub  202 , further comprising a Luer sideport  204 , a through lumen  216 , a hemostasis valve  208 , and a side pressurization lumen  214 . The proximal end  200  further comprises a catheter shaft or length of catheter tubing  212  further comprising a through lumen  206  and a pressurization lumen  210 . 
     Referring to  FIG. 2 , the catheter  212  is affixed to the hub  202  by adhesives, welding, insert molding, or the like. The pressurization lumen  214  of the hub  202  is operably connected to the pressurization lumen  210  inside the catheter tubing  212 . The Luer port  204  is operably connected to the pressurization lumen  214 , which is operably connected to the catheter pressurization lumen  210 . The hemostasis valve  208  is affixed to the proximal end of the hub  202 . The hemostasis valve  208  comprises a central lumen (not shown), which is operably connected to the central lumen  216  of the hub  202 . The central hub lumen  216  is operably connected to the through lumen  206  of the catheter. 
       FIG. 3A  illustrates an exterior view of the distal end  100  of the catheter comprising the catheter tube  212  further comprising the pressure lumen  210  and the through lumen  206 . The distal end  100  further comprises the bag  106 , the proximal bag to catheter weld  108 , the expandable structure  102 , and the distal expandable structure to catheter weld  112 . 
     Referring to  FIG. 3A , the ring (not shown) is retracted proximally under the bag  106  and so is not visible. The optional external restraint or sleeve  120  of  FIG. 1B  is not present in this embodiment. The elements of the expandable structure  102 , which in this embodiment is a mesh, are stretched out longitudinally to nearly parallel the axis of the catheter shaft  212 . 
       FIG. 3B  illustrates an exterior view of the distal end  100  of the catheter comprising the catheter tube  212  further comprising the pressure lumen  210  and the through lumen  206 . The distal end  100  further comprises the bag  106 , the proximal bag to catheter weld  108 , the expandable structure  102 , and the distal expandable structure to catheter weld  112 . 
     Referring to  FIG. 3B , the bag  106  has been inflated and its distal end has uneverted and moved distally to force the proximal end of the mesh  102  distally. The mesh  102  has become an expanded annular structure with a greater diameter or lateral dimension than in its unexpanded state of  FIG. 3A . The fold or eversion at the distal end of the bag  106  is visible up against the proximal end of the mesh  102 . The ring  104  can move a distance of about 1 mm to about 20 mm and, in a preferred embodiment the ring  104  can move about 2 mm to about 10 mm, and in a more preferred embodiment the ring  104  can move about 3 mm to about 6 mm. 
     The expandable structure  102  can take the form of a mesh, or a series of fingers, battens, rods, or a malecot, longitudinally disposed along the exterior of the catheter shaft  212  but disconnected from the catheter shaft  212  except at the distal bond  112  and at the slidably movable ring  104  hidden under the bag  204 . The mesh can be fabricated from polymeric materials such as PET, Nylon, PEEK, silicone, or the like, or it can be fabricated from metals such as nitinol, stainless steel, tantalum, platinum, cobalt nickel alloy, and the like. 
     The catheter shaft can range from about 1 French to about 7 French in outside diameter with a preferred range of about 2 French to about 5 French in outside diameter. The expandable structure  102 , when fully expanded, can range in outside diameter from about 3 French to about 15 French, depending on the diameter of the catheter shaft. 
       FIG. 4A  illustrates a side view, in partial breakaway of the distal end  450  of a therapeutic catheter  400 . The distal end  450  comprises a guidewire  402 , an inner catheter tube  410  further comprising an inner catheter tube lumen  412 , an outer catheter tube  414  further comprising an outer catheter tube lumen  416 , an annular piston  404 , a pusher  406 , an elastomeric sleeve  408 , a proximal expandable member bearing  428 , a proximal bearing attachment  429 , an expandable member  426 , a fluid impermeable layer  430 , one or more expandable member radiopaque markers  418 , an expandable member distal end  420 , a distal expandable member bond  424 , and a distal radiopaque tube marker  422 . In this illustration, the catheter distal end  450  is typically deployed within the cardiovascular system such that the natural blood flow moves from the proximal end toward the distal end, but the reverse direction is also possible. 
     Referring to  FIG. 4A , the inner tube  410  is disposed generally concentrically within the lumen  416  of the outer tube  414  and is constrained not to slide longitudinally relative to the outer tube  414 . The distal end  420  of the expandable structure  426  is affixed at its distal end to the inner tube  410  by the distal bond  424 . The distal end  420  of the expandable structure  426  can be affixed to the inner tube  410  near the distal end of the inner tube  410  but could also be affixed substantially proximal to that location resulting in substantial projection of the inner tube  410  beyond the distal end  420  of the expandable structure  426 . The expandable member  426  can comprise any structure including mesh, weave, braid, longitudinally oriented bars or struts, or the like. In a preferred embodiment, the expandable member  426  comprises a braid of stainless steel, cobalt nickel alloy, nitinol, or other high-spring, biocompatible metal wires having spring temper and having individual strand diameters of about 0.001 inches. The pick count of the braid can be between 5 and 100 picks per inch and the number of ends can range between about 6 to about 64. The length of the expandable member  426  can range from about 1-mm to about 300-mm and the outer diameter of the expandable member can range from about 1 mm to about 40 mm, depending on the target vessel and its therapeutic or diagnostic purpose, when in the fully expanded configuration. The inner catheter shaft or tube  410  can range from about 1-French to about 10-French in outside diameter with a preferred range of about 2-French to about 5-French in outside diameter. The guidewire  402  is slidably disposed within the lumen  412  of the inner tube  410  and is used to track the catheter  400  or maintain position within a lumen. 
     The distal end of the annular piston  404  is affixed to the proximal end of the pusher  406  by welding, mechanical attachment, bonding, or the like. The annular piston  404  is sized to fit between the inner diameter of the outer tube  414  and the outer diameter of the inner tube  410 . The piston  404  rides within the inner lumen  416  of the outer tube  414  but its travel space is reduced by the presence of the inner tube  410  thus resulting in an annulus-shaped inner lumen  416 . The annular piston  404  can slide along the longitudinal axis of the tubes but maintains a fluid-tight gap between the two tubes. 
     The pusher  406  can be fabricated as a cylinder, one or more rods, a cone, a coiled cylinder with no gaps between the coils, a conical coil with no gaps between the coils, or similar structure. The coil configuration permits flexibility along the region of the pusher while maintaining column strength. The pusher  406  is affixed, at its distal end, to the proximal end bearing  428  of the expandable member  426 , or to the proximal end of the expandable member  426 , itself, by the proximal bearing attachment or bond  429 . The proximal end bearing  428  of the expandable member  426  can have its inner surface lined with lubricious materials such as, but not limited to, PTFE, silicone oil, PFA, FEP, or the like so that it slides with minimal interference or restraint over the outside diameter of the inner tube  410 . The pusher  406  preferably has in inside diameter that clears the inner tube  410  so that friction is very low or non-existent in this region. The proximal end bearing  428  is affixed to the proximal end of the expandable member  426 . 
     The elastomeric sleeve  408  serves as a return spring for the proximal end of the expandable member  426 . The elastomeric sleeve is affixed to the distal end of the outer tube  414  at its proximal end and to the proximal end of the expandable member, the distal end of the pusher, or to the proximal end bearing  428 . The elastomeric sleeve  408  can be configured as a polymeric cylinder or conical cylinder. In other embodiments, the elastomeric sleeve  408  can be configured such that it is not a sleeve but a linear, coiled, bent, or serpentine spring. The elastomeric sleeve  408  can be fabricated from materials such as, but not limited to, polyurethane, Chronoprene™, stainless steel, nitinol, cobalt nickel alloy, titanium, silicone elastomer, or the like. 
     The fluid impermeable layer  430  is optional and is configured to line the inside, the outside, or both of the expandable member  426 . The fluid impermeable layer  430  can be disposed over the entirety or a portion of the expandable member  426 . The fluid impermeable layer  430  can comprise a thin membrane. The fluid impermeable layer can comprise a polymeric material. 
       FIG. 4B  Illustrates a side, partial breakaway, view of the distal end  450  of the catheter  400  of  FIG. 4A  in its second, radially expanded configuration. The distal end  450  comprises the guidewire  402 , the inner catheter tube  410  further comprising the inner catheter tube lumen  412 , the outer catheter tube  414  further comprising the outer catheter tube lumen  416 , the annular piston  404 , the pusher  406 , the elastomeric sleeve  408 , the proximal expandable member bearing  428 , the proximal bearing attachment  429 , the expandable member  426 , the fluid impermeable layer  430 , the expandable member radiopaque markers  418 , the expandable member distal end  420 , the distal expandable member bond  424 , and the distal radiopaque tube marker  422 . 
     The annulus-shaped lumen  416  is pressurized with fluid, preferably liquid, and has forced the annular piston  404  toward the distal end of the outer tube  414 . The annular piston  404  has moved closer to the distal end of the outer tube  414  forcing the pusher  406  to move distally over the stationary inner tube  410 . 
     The pusher forces the proximal end of the expandable region  426  to move distally to reduce the distance between the proximal end and bearing  428  relative to the stationary distal end  420  of the expandable region  426 . The axial length reduction of the expandable region  426  as generated a laterally directed outward displacement of the center of the expandable region  426 . 
     The elastomeric sleeve  408  has stretched and is generating a restorative bias force to pull the proximal end of the expandable region  426  back to its unexpanded condition. The length of the pusher  406  is configured to permit optimal performance of the elastomeric sleeve  408 , the spring function of which is improved by having a substantial length over which to operate such that the structure is not strained beyond its elastic limit. 
       FIG. 5  illustrates the proximal end  500  of the catheter  400  in a side, partial breakaway view. The proximal end  500  comprises a hub  502  further comprising a central lumen access port  508 , a side lumen access port  504 , and a side lumen manifold lumen  506 . The proximal end  500  further comprises the guidewire  402 , the inner catheter tube  410  further comprising the inner catheter tube lumen  412 , the outer catheter tube  414  further comprising the outer catheter tube lumen  416 , and the strain relief  518 . 
     Referring to  FIG. 5 , the hub  502  is bonded, welded, overmolded, or otherwise affixed to the inner tube  410  and the outer tube  414  such that the inner lumen  412  of the inner tube  410  is operably connected to the through inlet port  508 . The inner lumen  416  of the outer tube  414  is operably connected to the side manifold lumen  506  which is operably connected to the side inlet port  504 . The inner lumen  416  forms an annulus with the outside diameter of the inner tube  410 . Access to the inner lumen  416  can be obtained through a port, as illustrated, or through the proximal end of the outer tube  414 , in other embodiments. In the illustrated embodiment, the proximal end of the inner lumen  416  is sealed against fluid leakage so that the manifold lumen  506  provides the only access to the inner lumen  416  at the proximal end  500  of the catheter  400 . The side inlet port  504  and the through inlet port  508  are preferably configured with Luer type fittings but can be configured with other bayonet, screw, clamp, press-fit, or quick connect features. The proximal end of the strain relief  518  is affixed to the hub  502  and the distal end is coaxially disposed over the outer tube  414 . The distal end of the strain relief  518  can be affixed to the outer tube  414  or be longitudinally free to move. 
     The through inlet port  508  generally accepts the guidewire  402  and is preferably affixed, and operably connect, to a hemostasis valve (not shown). The side inlet port  504  is configured for high pressure injection of fluid, preferably liquids such as, but not limited to, water, saline, radiopaque dye contrast media, or a combination thereof. Fluid injected into the side inlet port  504  flows through the manifold lumen  506  into the annulus  416  within the outer tube  414  such that it pressurizes the lumen annulus  416  and moves the annular piston  404  of  FIGS. 4A and 4B . Withdrawal of vacuum on the side inlet port  504  can be used to generate a corresponding proximal motion of the annular piston  404  to augment or completely generate proximal movement of the proximal end of the expandable member  426  of  FIGS. 4A and 4B . 
     The catheter is inserted into the patient through an already placed guide catheter or over an already placed guidewire. The catheter can be inserted using a cutdown or using percutaneous technique. The percutaneous technique can include techniques such as the Seldinger technique in which a hollow needle is introduced into the vessel through the skin followed by guidewire insertion and removal of the hollow needle to permit a catheter to be placed over the guidewire, or similar types of methodology. The catheter, in other embodiments, can be inserted simultaneously with the guidewire such that maneuvering and steering is accomplished with a bent end of the guidewire or the expandable catheter. Once advanced to the desired location, the expandable catheter position is confirmed under fluoroscopy, ultrasound, MRI or other imaging modality. 
     Fluid can be injected, under pressure, into the inflation port on the proximal hub of the catheter. The fluid pressurizes a region inside a bladder or bag causing axial movement of a ring attached to the proximal or distal end of an expandable region. The bladder or bag is restricted from radial expansion due to inelastic properties, inelastic reinforcing materials, or a restraining sleeve or mesh such as a weave, braid, knit or other structure. One end of the bag or bladder is affixed to the catheter shaft but the other end of the bladder or bag is affixed to the ring and forces the ring to move along the axis of the catheter shaft, slidably movable thereupon. The fluid is injected by the operator using a syringe or a commercial inflation device comprising a syringe and a threaded jack screw or ratcheting mechanism. A small syringe, such as one with a ¼ cc volume can generate more than 1000 PSI under thumb pressure. Larger syringes can generate less pressure but provide higher fluid volumes. The volume required will be small and is a function of the annulus between the catheter shaft and the bag or the annulus between the inner tube  410  and outer tube  414 . 
     By infusing fluid into the pressurization channel and the volume under the bag, the ring can be moved and the expandable region expanded diametrically. The catheter can be used for a variety of therapeutic or diagnostic purposes including, but not limited to, embolic material introduction, implant (e.g. stent) deployment, temporary flow restoration, thrombolytic material introduction, neck bridging, aneurysm embolization, embolization of arteriovenous malformations (AVM), embolic protection filter deployment, radiopaque contrast injection, and MRA fluid injection. 
     Upon completion of the therapy or diagnostics, fluid is removed from the pressure port and pressure lumen. Upon removal of the fluid, the expandable region can return to its initial, unexpanded state under its own resilience. The expandable region can be fabricated from elastomeric or spring materials to facilitate this restoration movement. The restoration to unexpanded state can be enhanced by the addition of a spring between the ring and the proximal bond between the bag and catheter shaft, or other suitable location. The catheter can now be moved to a new location or removed from the body vessel or lumen. The guidewire, guide catheter, or both can be left in place following removal of the catheter with the expandable element. 
     While the preferred embodiments of the devices and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the inventions. The elements of the various embodiments may be incorporated into each of the other species to obtain the benefits of those elements in combination with such other species, and the various beneficial features may be employed in embodiments alone or in combination with each other. Other embodiments and configurations may be devised without departing from the spirit of the inventions and the scope of the appended claims.