US20050277979A1 - Apparatus and methods for treating stroke and controlling cerebral flow characteristics - Google Patents

Abstract

Apparatus and methods for treatment of stroke are provided. In a preferred embodiment, the present invention disposes at least one catheter having a distal occlusive member in the common carotid artery of the hemisphere of the cerebral occlusion. Retrograde flow may be provided through the catheter to effectively control cerebral flow characteristics. Under such controlled flow conditions, a thrombectomy device may be used to treat the occlusion, and any emboli generated are directed into the catheter.

Description

REFERENCE TO RELATED APPLICATION
• The present application is a continuation of U.S. patent application Ser. No. 10/115,333 filed Apr. 1, 2002 which is a continuation in part of U.S. patent application Ser. No. 09/972,225 filed Oct. 4, 2001
FIELD OF THE INVENTION
• The present invention relates to improved apparatus and methods for treatment of stroke. More specifically, the apparatus and methods of the present invention are directed to treating stroke by controlling cerebral blood flow and removing thrombi and/or emboli.
BACKGROUND OF THE INVENTION
• Cerebral occlusions that lead to stroke require swift and effective therapy to reduce morbidity and mortality rates associated with the disease. Many current technologies for treating stroke are inadequate because emboli generated during the procedure may travel downstream from the original occlusion and cause ischemia. There is currently a need for a stroke treatment system that provides a swift and efficient treatment for occlusions while simultaneously controlling cerebral flow characteristics.
• In the initial stages of stroke, a CT scan or MRI may be used to diagnose the cerebral occlusion, which commonly occurs in the middle cerebral arteries. Many current technologies position a catheter proximal to the occlusion, then deliver clot dissolving drugs to treat the lesion. A drawback associated with such technology is that delivering drugs may require a period of up to six hours to adequately treat the occlusion. Another drawback associated with lytic agents (i.e., clot dissolving agents) is that they often facilitate bleeding.
• When removing thrombus using mechanical embolectomy devices, it is beneficial to engage the thrombus and remove it as cleanly as possible, to reduce the amount of emboli that are liberated. However, in the event that emboli are generated during mechanical disruption of the thrombus, it is imperative that they be subsequently removed from the vasculature.
• Many current drug delivery and mechanical treatment methods are performed under antegrade flow conditions. Such treatment methods do not attempt to manipulate flow characteristics in the cerebral vasculature, e.g., the Circle of Willis and communicating vessels, such that emboli may be removed. Accordingly, there remains a need to provide effective thrombus and emboli removal from the cerebral vasculature while simultaneously controlling flow within that vasculature.
• U.S. Pat. No. 6,161,547 to Barbut (Barbut '547) describes a technique for enhancing flow in the cerebral vasculature in treating patients with acute stroke or other cerebrovascular disease. The technique involves: (1) positioning a first tubular member in a vascular location suitable for receiving antegrade blood flow; (2) positioning a second tubular member in a contralateral artery of the occlusion (e.g., for an occlusion located in the left common carotid artery the second tubular member is placed in the right common carotid artery); and coupling the first tubular member to the second tubular member using a pump and filter.
• The first tubular member receives antegrade blood flow and channels the blood to the pump and filter, where the blood then is reperfused via the second tubular member into the contralateral artery, thus increasing blood flow to the opposing hemisphere of the brain. The first and second tubular members may include balloons disposed adjacent to their distal ends.
• The techniques described in the foregoing patent have several drawbacks. For example, if the first balloon of the first tubular member is deployed in the left common carotid artery, as shown inFIG. 7C of that patent, aspiration of blood from the vessel between the balloon and the occlusion may cause the vessel to collapse. On the other hand, if the balloon is not deployed, failure to stabilize the distal tip may result in damage to the vessel walls. In addition, failure to occlude the vessel may permit antegrade blood flow to be diverted into that apparatus, rather than blood distal to the first tubular member.
• The Barbut '547 patent further discloses that inflating the balloon of the second tubular member may assist in controlling the flow to the contralateral artery or provide more efficient administration of pharmacotherapy to the cerebral tissues. However, when that balloon is deployed, the contralateral artery may be starved of sufficient flow, since the only other flow in that artery is that aspirated through the first tubular member. On the other hand, if the balloon of the second tubular member is not inflated, no flow control is possible.
• A method for removing cerebral occlusions is described in U.S. Pat. No. 6,165,199 to Barbut (Barbut '199). This patent describes a catheter having an aspiration port at its distal end that communicates with a vacuum at its proximal end. A perfusion port disposed in a lateral surface of the catheter may be used to enhance antegrade flow in collateral arteries. In use, the aspiration port is positioned proximal to an occlusion to provide a direct suction effect on the occlusion. The perfused flow in collateral arteries is intended to augment retrograde flow distal to the occlusion, such that the occlusion is dislodged via the pressure and directed toward the aspiration port. A chopping mechanism, e.g., an abrasive grinding surface or a rotatable blade, coupled to the aspiration port recognizes when the aspiration port is clogged. The chopping mechanism then engages to break up the occlusion and permit it to enter the aspiration port in smaller pieces.
• The device described in the Barbut '199 patent has several disadvantages. First, the use of a vacuum to aspirate the occlusion requires an external pressure monitoring device. The application of too much vacuum pressure through the aspiration port may cause trauma, i.e., collapse, to the vessel wall. Also, because the system is intended to dislodge the occlusion using a pressure differential, a chopping mechanism is required to prevent the entire mass from clogging the aspiration port. The use of a chopping mechanism, however, may generate such a large quantity of emboli that it may be difficult to retrieve all of the emboli. In addition, emboli generated by the action of the chopping mechanism may accumulate alongside the catheter, between the aspiration port and the distal balloon. Once this occurs, it is unclear how the emboli will be removed.
• Yet another drawback of the device described in the Barbut '199 patent is that high-pressure perfusion in collateral arteries may not augment retrograde flow distal to the occlusion as hypothesized. The patent indicates that high-pressure perfusion in collateral arteries via side ports in the catheter may be sufficient to cause an increase in pressure distal to the occlusion. Antegrade blood flow from the heart in unaffected arteries, e.g., other vertebral and/or carotid arteries, may make it difficult for the pressure differential induced in the contralateral arteries to be communicated back to the occluded artery in a retrograde fashion.
• Other methods for treating ischemic brain stroke have involved cerebral retroperfusion techniques. U.S. Pat. No. 5,794,629 to Frazee describes a method that comprises at least partially occluding the first and second transverse venous sinuses and introducing a flow of the patient's arterial blood to a location distal to the partial venous occlusions. As described in that patent, the infusion of arterial blood into the venous sinuses provides a retrograde venous flow that traverses the capillary bed to oxygenate the ischemic tissues and at least partially resolve ischemic brain symptoms.
• One drawback associated with the technique described in the Frazee patent is that the pressure in the transverse venous sinuses must be continuously monitored to ensure that cerebral edema is avoided. Because the veins are much less resilient than arteries, the application of sustained pressure on the venous side may cause brain swelling, while too little pressure may result in insufficient blood delivered to the arterial side.
• In addition to the foregoing methods to augment cerebral perfusion, several methods are known for mechanically removing clots to treat cerebral occlusions. U.S. Pat. No. 5,895,398 to Wensel et al. (Wensel) describes a shape-memory coil affixed to an insertion mandrel. The coil is contracted to a reduced profile state within the lumen of a delivery catheter, and the catheter is used to cross a clot. Once the coil is disposed distal to the clot, the coil is deployed. The coil then is retracted proximally to engage and remove the clot.
• A primary drawback associated with the device described in the Wensel patent is that the deployed coil contacts the intima of the vessel, and may damage to the vessel wall when the coil is retracted to snare the occlusion. Additionally, the configuration of the coil is such that the device may not be easily retrieved once it has been deployed. For example, once the catheter has been withdrawn and the coil deployed distal to the occlusion, it may be difficult or impossible to exchange the coil for another of different dimensions.
• U.S. Pat. No. 5,972,019 to Engelson et al. (Engelson) describes a deployable cage assembly that may be deployed distal to a clot. Like the Wensel device, the device described in the Engelson patent is depicted as contacting the intima of the vessel, and presents the same risks as the Wensel device. In addition, because the distal end of the device comprises a relatively large profile, the risk of dislodging emboli while crossing the clot is enhanced, and maneuverability of the distal end of the device through tortuous vasculature may be reduced.
• In view of these drawbacks of previously known clot removal apparatus and methods, it would be desirable to provide apparatus and methods for controlling hemodynamic properties at selected locations in the cerebral vasculature, e.g., the Circle of Willis and communicating vessels.
• It also would be desirable to provide apparatus and methods for removal and recovery of thrombi and/or emboli above the carotid bifurcation.
• It still further would be desirable to provide apparatus and methods that quickly and efficiently treat cerebral occlusions.
SUMMARY OF THE INVENTION
• In view of the foregoing, it is an object of the present invention to provide apparatus and methods for controlling hemodynamic properties at selected locations in the cerebral vasculature.
• It is also an object of the present invention to provide apparatus and methods for removal and recovery of thrombi and/or emboli above the carotid bifurcation.
• It is a further object of the present invention to provide apparatus and methods that quickly and efficiently treat cerebral occlusions.
• These and other objects of the present invention are accomplished by providing a stroke treatment system comprising an emboli removal catheter suitable for manipulating blood flow in the cerebral vasculature. The stroke treatment system may facilitate the introduction of clot lysing agents alone or in conjunction with a thrombectomy element.
• In a preferred embodiment, the emboli removal catheter is transluminally inserted and disposed in the common carotid artery CCA, and comprises a flexible catheter having an occlusive member disposed on its distal end. The occlusive member is configured to be deployed to anchor the catheter and occlude antegrade flow in the CCA. Optionally, a separate occlusive element that is configured to pass through a lumen of the emboli removal catheter may be deployed in the external carotid artery ECA to occlude flow through that vessel. When the emboli removal catheter is deployed in the CCA and used in conjunction with the occlusive element deployed in the ECA, flow characteristics in the cerebral vasculature, including flow in the middle cerebral artery MCA, may be influenced by the flow through the lumen of the emboli removal catheter.
• With flow controlled at the selected cerebral locations, the distal end of a thrombectomy element then may be advanced across the lesion. Lytic agents may be infused directly into the lesion via a drug delivery lumen of an outer sheath that contains the thrombectomy element in a contracted state. After the lytic agents have been infused for a desired time, the thrombectomy element may be self-deployed distal to the occlusion by proximally retracting the outer sheath. The thrombectomy element then may be retracted to snare a remaining portion of the lesion, i.e., a portion that was not removed via the lytic process, and the thrombectomy element then is retracted into the emboli removal catheter. Because retrograde or redistributed flow has been generated in the cerebral vasculature, emboli liberated during the lytic process and/or actuation of the thrombectomy element are directed into the emboli removal catheter for removal.
BRIEF DESCRIPTION OF THE DRAWINGS
• Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments, in which:
• FIG. 1 provides a schematic overview of the portion of the vasculature in which the apparatus and methods of the present invention are intended for use;
• FIG. 2 provides an overview of the apparatus of the present invention deployed in a patient's vasculature;
• FIGS. 3A-3D are, respectively, a schematic view of apparatus in accordance with the present invention, detailed side and sectional views of the distal end of an emboli removal catheter of the present invention, and a cross-sectional view of the emboli removal catheter;
• FIGS. 4A-4B are views of alternative embodiments of low profile occlusive elements for occluding flow in the external carotid arteries;
• FIGS. 5A-5F depict thrombectomy wires having shape memory properties in contracted and deployed states;
• FIGS. 6A-6D describe apparatus comprising a thrombectomy wire having drug delivery capabilities; and
• FIGS. 7A-7E illustrate method steps for controlling cerebral blood flow and removing thrombi and/or emboli in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
• Referring toFIG. 1, a schematic of the pertinent vasculature relating to the present invention is provided. Many cerebral obstructions that lead to stroke reside in the middle cerebral arteries MCA. To treat obstructions in the MCA, one approach involves percutaneously and transluminally advancing a therapeutic device to the site of the obstruction via the internal carotid artery ICA.
• It is well known in the art to percutaneously and transluminally advance a catheter in retrograde fashion toward coronary vasculature, e.g., via the femoral artery, external iliac artery, descending aorta DA and aortic arch AA. To access cerebral vasculature, including obstructions residing in the MCA, one approach is to further advance a catheter and/or therapeutic devices in antegrade fashion from the aortic arch AA, into the common carotid artery CCA, up through the ICA and into the middle cerebral artery MCA, as shown inFIG. 1.
• Treating occlusions in the MCA may generate emboli upon removal of the occlusion. Under normal blood flow conditions, such emboli may travel downstream from the original occlusion and cause ischemia. Accordingly, it is advantageous to manipulate blood flow characteristics in the cerebral vasculature to ensure that emboli generated in the MCA are effectively removed.
• FIG. 2 provides an overview of the components of the system of the present invention, each of which are described in greater detail hereinbelow.Emboli removal catheter2 includes distal occlusive element4, and is configured to be percutaneously advanced in retrograde fashion through the descending aorta. Occlusive element4 preferably comprises a pear-shaped or funnel-shaped balloon as described in co-pending and commonly assigned U.S. patent application Ser. No. 09/418,727, which is incorporated herein by reference. Occlusive element4 preferably is positioned proximal to the carotid bifurcation, and then deployed to induce retrograde flow in the ICA by use of a venous return catheter (not shown) that communicates with the proximal end ofcatheter2.Balloon10, also described in the foregoing application, is deployed in the ECA to ensure that retrograde flow from the ECA is not carried in an antegrade fashion into the ICA.
• Applicant has determined that when occlusive element4 is deployed proximal to the carotid bifurcation, andballoon10 is deployed in the ECA, the retrograde flow induced in the ICA by use of the venous return catheter (described hereinbelow with respect toFIG. 3A) is sufficient to manipulate flow in the cerebral vasculature, and more specifically, in the MCA. Moreover,balloon10 may be omitted in the case where the ECA already has been sufficiently occluded by an existing vascular occlusion, in which case emboliremoval catheter2 may be used alone to influence cerebral flow.Emboli removal catheter2 may used to suspend antegrade flow in the cerebral arteries and to selectively suspend or redistribute flow in the cerebral vasculature.
• InFIG. 2,thrombectomy wire12 comprisesknot14 that is deployed distal to the thrombusT. Thrombectomy wire12 and thrombus T then are retracted proximally into the lumen ofemboli removal catheter2, and any embolic fragments generated during this procedure are directed intocatheter2 by inducing cerebral retrograde flow.
• Referring now toFIG. 3A,stroke treatment apparatus40 constructed in accordance with the principles of the present invention is described.Apparatus40 comprisesemboli removal catheter41,wire45,venous return line52,tubing49 andoptional blood filter50.
• Catheter41 includes distalocclusive element42,hemostatic ports43aand43b,e.g., Touhy-Borst connectors,inflation port44, andblood outlet port48.Wire45 includesballoon46 that is inflated viainflation port47.Tubing49 couplesblood outlet port48 to filter50 andblood inlet port51 ofvenous return line52.
• Wire45 preferably comprises a small diameter flexible shaft having an inflation lumen that couplesinflatable balloon46 toinflation port47.Wire45 andballoon46 are configured to pass throughhemostatic ports43aand43band the aspiration lumen of catheter41 (seeFIGS. 3C and 3D), so thatballoon46 may be disposed in a communicating artery, e.g., the external carotid artery.Ports43aand43band the aspiration lumen ofcatheter41 are sized to permit additional interventional devices, such as thrombectomy wires, to be advanced through the aspiration lumen whenwire45 is deployed.
• Venous return line52 includeshemostatic port53,blood inlet port51 and a lumen that communicates withports53 and51 andtip54.Venous return line52 may be constructed in a manner per se known for venous introducer catheters.Tubing49 may comprise a suitable length of a biocompatible material, such as silicone. Alternatively,tubing49 may be omitted andblood outlet port48 ofcatheter41 andblood inlet port51 ofvenous return line52 may be lengthened to engage either end offilter50 or each other.
• With respect toFIGS. 3B and 3C, distalocclusive element42 comprises expandable funnel-shapedballoon55. In accordance with manufacturing techniques which are known in the art,balloon55 comprises a compliant material, such as polyurethane, latex or polyisoprene which has variable thickness along its length to provide a funnel shape when inflated.Balloon55 is affixed todistal end56 ofcatheter41 in an inverted fashion, for example, by gluing or a melt-bond, so that opening57 inballoon55 leads intoaspiration lumen58 ofcatheter41.Balloon55 preferably is wrapped and heat treated during manufacture so thatdistal portion59 of the balloon extends beyond the distal end ofcatheter41 and provides an atraumatic tip or bumper for the catheter.
• As shown inFIG. 3D,catheter41 preferably comprisesinner layer60 of low-friction material, such as polytetrafluoroethylene (“PTFE”), covered with a layer of flat stainlesssteel wire braid61 and polymer cover62 (e.g., polyurethane, polyethylene, or PEBAX).Inflation lumen63 is disposed withinpolymer cover62 and couplesinflation port44 toballoon55.
• Referring toFIGS. 4, alternative embodiments forwire45 andballoon46 ofFIG. 3A are described for use in occluding a communicating artery, e.g., the external carotid artery. InFIG. 4A,occlusive device121 comprisesproximal hub120,hypo tube127,shaft128,balloon136 andcoil142.Hypo tube127 preferably comprises stainless steel, whileshaft128 preferably comprises a radiopaque material.Balloon136 is configured using a tubular balloon material, e.g., chronoprene, that is compliant in nature and provides a self-centering balloon when deployed. The proximal end ofballoon136 is secured toradiopaque shaft128 byband132 andtaper130. The distal end ofballoon136 is affixed tocoil142 viataper140.
• Core wire122 is slidably disposed withinhypo tube127 so that its proximal end is disposed inproximal hub120 and its distal end is affixed to taper140. Fluid may be injected into the annulus surroundingcore wire122 so that the fluid exits intoballoon136 viainflation window134, thus permittingballoon136 to expand radially and longitudinally.Core wire122,taper140 andcoil142 may move distally to accommodate such linear extension.Stroke limiter123, disposed on the distal end ofcore wire122, ensures thatballoon136 does not extend longitudinally more a predetermined distance ‘x’.
• In the alternative embodiment ofFIG. 4B,occlusive device151 comprisesshaft152,balloon158, andcoil168.Shaft152 preferably comprises a radiopaque material and connects to a hypo tube similar to that ofFIG. 4A. The proximal components fordevice151, i.e., proximal toshaft152, are the same as the components that are proximal toshaft128 inFIG. 4A.
• Balloon158 is constrained at its proximal end byband156 havingproximal balloon marker157.Taper154 is provided on the proximal end ofband156 in alignment with the proximal end ofballoon158. The distal end ofballoon158 is everted, as shown inFIG. 4B, and secured withradiopaque band160 that provides a fluoroscopic reference for the distal boundary of the balloon.Taper164 further secures the everted distal section, sandwiching between the first and second folds.
• Core wire150 is affixed distally tocoil168 havingradiopaque marker170.Lumen159 communicates with an inflation port (not shown) at its proximal end and withinflation window166 at its distal end.Lumen159 permits the injection of fluids, e.g., saline, to deployballoon158. Core wire150 is slidably disposed in the hypo tube andshaft152 to prevent extension ofballoon158 up to a distance ‘x’, as indicated inFIG. 4A.
• Referring toFIGS. 5, apparatus suitable for removing thrombi are described. InFIG. 5A,thrombectomy wire200 having proximal and distal ends andatraumatic tip202 affixed to the distal end is depicted in a contracted state withincoil204.Atraumatic tip202 preferably comprises a ball-shape having a larger diameter thanwire200, as shown inFIG. 5A. In a preferred embodiment,thrombectomy wire200 comprises a shape-memory retaining material, for example, a Nickel Titanium alloy (commonly known in the art as Nitinol).
• The use of Nitinol generally requires the setting of a custom shape in a piece of Nitinol, e.g., by constraining the Nitinol element on a mandrel or fixture in the desired shape, and then applying an appropriate heat treatments, which are per se known.
• Coil204 coverswire200 along its length, up toatraumatic tip202. Ascoil204 is retracted proximally,wire200 self-expands to a predetermined knot configuration, as shown inFIG. 5B. In a preferred embodiment, the diameter ofwire200 is about 0.002 inches, the diameter ofatraumatic tip202 is about 0.014 inches, andcoil204 is manufactured using platinum. It should be appreciated that an outer sheath may be used in place ofcoil204, such that proximally retracting the outer sheath causeswire200 to self-deploy.
• Referring toFIG. 5C, a method for usingthrombectomy wire200 to snare a thrombus T, e.g., in middle cerebral artery MCA, is described.Thrombectomy wire200, initially contracted withincoil204, is advanced through a lumen ofcatheter2, then preferably is advanced in retrograde fashion via the ICA to the site of the cerebral lesion in the MCA. Under controlled flow conditions, i.e., conditions that will promote the flow of emboli towardcatheter2,atraumatic tip202 andcoil204 pierce thrombus T, as shown inFIG. 5C.
• Coil204 then is retracted proximally with respect towire200 to self-deployshape memory wire200 at a location distal to thrombus T, as shown inFIG. 5D.Wire200 then is retracted proximally to snare thrombus T, andatraumatic tip202 ofwire200 facilitates removal of the lesion.
• Referring toFIGS. 5E-5F, an alternative embodiment a thrombectomy wire ofFIGS. 5A-5B is described. InFIG. 5E,thrombectomy wire205 havingatraumatic tip208 is delivered in a contracted state withinslidable sheath206.Thrombectomy wire205 is configured to self-deploy to a predetermined shape, e.g., via use of a shape memory material, upon proximal retraction ofsheath206.Coil207 overlaysslidable sheath206 and is affixed toatraumatic tip208 atpoints209aand209b,e.g., via a solder or weld.Sheath206 initially is provided in a distalmost position such that it abutsatraumatic tip208 and constrainswire205 along its length.Sheath206 advantageously enhances the distal pushability of the device, particularly when the device is advanced though an occlusion.
• Upon positioning the distal end ofwire205 at a location distal to the occlusion,sheath206 is retracted proximally to causewire205 to self-deploy, preferably to a knot-shaped configuration, as depicted inFIG. 5F.Coil207, affixed toatraumatic tip208 ofwire205, conforms to the shape ofwire205. The deployed knot-shaped device then is proximally retracted to snare the occlusion, according to methods described hereinabove.
• Referring toFIG. 6, alternative apparatus suitable for removing thrombi are described. InFIG. 6A,thrombectomy wire300 having proximal and distal ends andatraumatic tip302 affixed to the distal end is depicted in a contracted state withinouter sheath306, also having proximal and distal ends. In a preferred embodiment,thrombectomy wire300 comprises a shape-memory retaining material, for example, Nitinol, which may heat treated according to techniques described hereinabove. Accordingly, whenouter sheath306 is retracted proximally, a distal section ofwire300 self-expands, preferably to a predetermined knot-shaped configuration, as shown inFIG. 6B.
• Coil304 preferably is disposed about a distal section ofwire300 that comprises a smaller diameter relative to a proximal section ofwire300, so that the addition ofcoil304 does not increase the distal profile ofwire300 with respect to the proximal section.Coil304 preferably is affixed to wire300 at a proximal end and further affixed to wire300 and/oratraumatic tip302 at a distal end.
• Outer sheath306 preferably comprises at least onedrug delivery port307 disposed in a lateral surface ofouter sheath306.Drug delivery port307 more preferably is disposed near the distal end ofouter sheath306, as shown inFIG. 6A. An annulus formed betweenwire300 and an inner wall ofsheath306 formsdrug delivery lumen305.Drug delivery lumen305 is sized to permit the injection of lytic agents to the distal end ofouter sheath306, without providing so much space as to allowwire300 to assume its predetermined deployed shape. Additionally,drug delivery port309, which forms a space between the distal end ofsheath306 andatraumatic tip302, may be used to deliver lytic agents to a treatment site, preferably whenatraumatic tip302 is disposed substantially within a stenosis.
• Referring toFIG. 6C, a method for usingthrombectomy wire300 in conjunction withouter sheath306 to remove a thrombus T, e.g., located in middle cerebral artery MCA, is described.Thrombectomy wire300, which initially is provided in a contracted state withinouter sheath306, is advanced through a lumen ofcatheter2, then preferably is advanced in retrograde fashion via the internal carotid artery to the site of the cerebral lesion in the MCA. Under controlled flow conditions, i.e., conditions that will promote the flow of emboli towardcatheter2,atraumatic tip302 then pierces thrombus T, andwire300 andsheath306 may be advanced distally beyond thrombus T, as shown inFIG. 6C.
• Outer sheath306 preferably is positioned so that at least onedrug delivery port307 is disposed within thrombus T, as shown inFIG. 6C. At this time,lytic agents312 may be introduced intodrug delivery lumen305, e.g., via a proximal port (not shown) that is in fluid communication with the proximal end ofouter sheath306.Lytic agents312 are advanced toward the distal end ofsheath306, and may exitsheath306 throughdrug delivery port307 so that they are infused into thrombus T, as shown inFIG. 6C. Alternatively,atraumatic tip302 and the distal end ofouter sheath306 may be disposed substantially within thrombus T, andlytic agents312 may be delivered to thrombus T viadrug delivery port309 ofFIG. 6A.
• Lytic agents312 may partially or fully disrupt thrombus T, and any emboli generated during the lytic process is carried towardcatheter2 via the controlled flow previously established in the region. With thrombus T having been at least partially disrupted,outer sheath306 then may be retracted proximally with respect towire300 to self-deploywire300 at a location distal to thrombus T, as shown inFIG. 6D.Wire300 then is retracted proximally to snare a remaining portion of thrombus T, andatraumatic tip302 ofwire300 facilitates removal of the lesion.
• Referring now toFIG. 7, a preferred method for using the apparatus described hereinabove to treat stroke, in accordance with principles of the present invention, is described.
• Referring toFIG. 7A,catheter404 ofFIG. 3A is positioned in the common carotid artery CCA usingguide wire406.Catheter404 is positioned proximal of the carotid bifurcation, as shown, preferably in the hemisphere in which the cerebral occlusion is located.Balloon408, for example, as described hereinabove with respect toFIG. 4, then may be disposed in the external carotid artery ECA and deployed, as shown inFIG. 7B. Alternatively, if the ECA is already substantially occluded due to an existing lesion, then the use ofballoon408 may be omitted.
• Referring toFIG. 7C, distalocclusive element412 ofcatheter404 is deployed to occlude antegrade flow in the selected CCA.Venous return catheter52 ofFIG. 3A then is placed in a remote vein, such that negative pressure invenous return catheter52 during diastole establishes a continuous flow through the lumen ofcatheter404. This induces retrograde flow in the ICA, as depicted inFIG. 7C.Thrombectomy wire414, for example, as described with respect toFIG. 6 hereinabove, then may be advanced throughcatheter404 and into the cerebral vasculature via the ICA.
• Referring toFIG. 7D, a view of the cerebral vasculature under the conditions described inFIG. 7C is shown.Thrombectomy wire414 has been advanced to a location just proximal of thrombus T, for example, in middle cerebral artery MCA. The continuous flow through the lumen ofcatheter404 that induces retrograde flow in the ICA also influences flow in the MCA, as depicted inFIG. 7D, such that flow in the MCA is toward the aspiration lumen ofcatheter404.
• The distal end ofthrombectomy wire414 may be advanced distally across thrombus T, as shown inFIG. 7D.Thrombectomy wire414 preferably is advanced across thrombus T in a contracted state within outer sheath415 having proximal and distal ends. InFIG. 7D,thrombectomy wire414 and outer sheath415 preferably are constructed in accordance withthrombectomy wire300 andouter sheath306 ofFIG. 6, respectively. Outer sheath415 preferably comprises at least one drug delivery port disposed in a lateral surface near the distal end.
• In a preferred method, the distal end of outer sheath415 crosses thrombus T, as shown inFIG. 7D, and the drug delivery port of outer sheath415 is positioned within thrombus T. Lytic agents then may be delivered to thrombus T via the drug delivery port. Alternatively, the distal end of outer sheath415 may be positioned substantially within thrombus T, and lytic agents may be delivered to thrombus T viaport309 ofFIG. 6A.
• The introduction of lytic agents via outer sheath415 may be used to at least partially dislodge thrombus T, as shown inFIG. 7E. After delivering the lytic agents for the desired time, the distal end of outer sheath415 is positioned distal to thrombus T. Outer sheath415 then is retracted proximally to self-deploydeployable knot416 ofwire414 at a location distal to thrombus T, as shown inFIG. 7E.
• Deployable knot416 ofthrombectomy wire414 then may be retracted proximally to snare any remaining portion of thrombus T, as shown inFIG. 7E, and then is retracted intocatheter404. Any emboli generated during the procedure will be directed intocatheter404 via the established retrograde flow. Distalocclusive element412 and external carotidocclusive device408 then are contracted, andcatheter404 may be removed from the patient.
• It should be noted that the method steps described inFIG. 7 may be used in combination with any of the apparatus described hereinabove. For example, stoke treatment in accordance with the present invention may be performed primarily usingemboli removal catheter404 disposed in the common carotid artery to influence cerebral flow. Alternatively,emboli removal catheter404 of the present invention may be used in combination withocclusive element408 disposed in an external carotid artery. Additionally, the proximal end ofemboli removal catheter404 may be coupled to a syringe (not shown) that communicates with the lumen ofemboli removal catheter404, so that the syringe may be used to influence the aspiration throughemboli removal catheter404, which in turn influences cerebral flow.
• In yet a further alternative embodiment, a recovery catheter, i.e., a micro catheter, may be advanced throughcatheter404 and via the ICA to a location in closer proximity to the cerebral occlusion. Such an embodiment is described in detail in commonly assigned, co-pending U.S. patent application Ser. No. 09/972,225. Alternatively,thrombectomy wire414 may be replaced using a thrombectomy wire that rotationally engages and removes thrombus T, as opposed to snaring thrombus T. Such an embodiment also is described in detail in the above-referenced, co-pending application.
• While preferred illustrative embodiments of the invention are described above, it will be apparent to one skilled in the art that various changes and modifications may be made therein without departing from the invention. The appended claims are intended to cover all such changes and modifications that fall within the true spirit and scope of the invention.

Claims (23)

1. Apparatus suitable for treating stroke, the apparatus comprising:

a catheter having proximal and distal ends, a lumen extending therebetween, and an occlusive element disposed on the distal end, the occlusive element having an opening that communicates with the lumen, the occlusive element having a contracted position suitable for transluminal insertion and an expanded position wherein the occlusive element occludes antegrade flow in a vessel, wherein flow through the lumen of the catheter is configured to influence flow in a cerebral vessel when the catheter is disposed in a carotid artery; and

a deployable wire having proximal and distal ends, and further having a contracted state and a deployed state, wherein the deployable wire is adapted to be inserted into a patient's vessel in the contracted state, and wherein the distal end self-deploys to a predetermined shape in the deployed state.

2. The apparatus ofclaim 1 wherein the occlusive element comprises an inflatable balloon.

3. The apparatus ofclaim 1 further comprising:

a shaft having proximal and distal ends; and

a balloon having proximal and distal ends, the balloon being disposed near the distal end of the shaft.

4. The apparatus ofclaim 3 wherein the balloon is adapted to be disposed in a communicating artery.

5. The apparatus ofclaim 3 wherein the distal end of the balloon is everted.

6. The apparatus ofclaim 5 wherein the proximal end of the balloon is everted.

7. A method for manipulating cerebral blood flow characteristics, the method comprising:

providing apparatus comprising a catheter having proximal and distal ends, a lumen extending therebetween, and an occlusive element affixed to the distal end;

positioning the distal end of the catheter in a selected vessel in a contracted state;

deploying the occlusive element affixed to the catheter to occlude antegrade flow in the selected vessel; and

providing retrograde flow through the lumen of the catheter to influence flow in a cerebral vessel.

8. The method ofclaim 7 wherein deploying the occlusive element of the catheter occludes antegrade flow in at least a common carotid artery.

9. The method ofclaim 7 further comprising:

providing a shaft having proximal and distal ends and a balloon disposed near the distal end of the shaft; and

deploying the balloon in an external carotid artery.

10. Apparatus suitable for treating a vascular occlusion, the apparatus comprising:

a deployable wire having proximal and distal ends, and further having a contracted state and a deployed state, wherein the deployable wire is adapted to be inserted into a patient's vessel in the contracted state, and wherein the distal end self-deploys to a predetermined shape in the deployed state; and

an outer sheath having proximal and distal ends, wherein the outer sheath is configured to constrain the deployable wire in the contracted state,

wherein an annulus between the deployable wire and an inner surface of the outer sheath defines a drug delivery lumen that is in fluid communication with the distal end of the outer sheath.

11. The apparatus ofclaim 10 wherein the deployable wire comprises a shape-memory material.

12. The apparatus ofclaim 10 wherein the deployable wire further comprises an atraumatic tip affixed to the distal end.

13. The apparatus ofclaim 12 wherein a space between the distal end of the outer sheath and the atraumatic tip defines a drug delivery port, wherein the drug deliver port is in fluid communication with the drug delivery lumen.

14. The apparatus ofclaim 10 wherein the outer sheath comprises at least one drug delivery port disposed in a lateral surface of the outer sheath, wherein the drug delivery port is in fluid communication with the drug delivery lumen.

15. The apparatus ofclaim 10 wherein a distal section of the deployable wire comprises a smaller diameter relative to a proximal section of the deployable wire.

16. The apparatus ofclaim 15 wherein the deployable wire further comprises a coil disposed about a portion of the distal section.

17. The apparatus ofclaim 10 wherein the drug delivery lumen is configured to permit the delivery of at least one lytic agent to the distal end of the outer sheath.

18. The apparatus ofclaim 10 wherein the distal end of the deployable wire comprises a knot shape in the deployed state.

19. The apparatus ofclaim 10 wherein the deployable wire is substantially flush with an inner wall of a treatment vessel in the deployed state.

20. A method for treating a vascular occlusion, the method comprising:

providing a deployable wire having proximal and distal ends in a contracted state substantially within an outer sheath having proximal and distal ends; and

delivering at least one lytic agent to the occlusion via a drug delivery lumen, wherein the drug delivery lumen is defined by an annulus formed between the deployable wire and an inner surface of the outer sheath.

21. The method ofclaim 20 further comprising delivering the lytic agent to the occlusion via at least one drug delivery port disposed in a lateral surface of the outer sheath.

22. The method ofclaim 20 further comprising delivering the lytic agent to the occlusion via a space formed between the distal end of the outer sheath and the distal end of the deployable wire.

23. The method ofclaim 20 further comprising:

positioning the distal end of the outer sheath at a location distal to the occlusion;

proximally retracting the outer sheath to self-deploy the deployable wire at a location distal to the occlusion; and

proximally retracting the deployable wire to snare a remaining portion of the occlusion.

Images