US20110160762A1 - Apparatus and methods for reducing embolization during treatment of carotid artery disease - Google Patents

Abstract

Methods and apparatus are provided for removing emboli during an angioplasty, stenting or surgical procedure comprising a catheter having an occlusion element, an aspiration lumen, and a blood outlet port in communication with the lumen, a guide wire having a balloon, a venous return sheath with a blood inlet port, and tubing that couples the blood outlet port to the blood inlet port. Apparatus is also provided for occluding the external carotid artery to prevent reversal of flow into the internal carotid artery. The pressure differential between the artery and the vein provides reverse flow through the artery, thereby flushing emboli. A blood filter may optionally be included in-line with the tubing to filter emboli from blood reperfused into the patient.

Description

REFERENCE TO RELATED APPLICATIONS
• The present application is a divisional of pending U.S. patent application Ser. No. 11/156,865, filed Jun. 20, 2005, which is a divisional of pending U.S. patent application of Ser. No. 10/100,630, filed Mar. 15, 2002, now U.S. Pat. No. 6,908,474, issued Jun. 21, 2005, which is a continuation-in-part of U.S. patent application Ser. No. 09/418,727, filed Oct. 15, 1999, now U.S. Pat. No. 6,423,032, issued Jul. 23, 2002, which is a continuation-in-part of U.S. patent application Ser. No. 09/333,074, filed Jun. 14, 1999, now U.S. Pat. No. 6,206,868, which is a continuation-in-part of International Application PCT/US99/05469, filed Mar. 12, 1999, which is a continuation-in-part of U.S. patent application Ser. No. 09/078,263, filed May 13, 1998, now U.S. Pat. No. 6,413,235, Issued Jul. 2, 2002.
FIELD OF THE INVENTION
• This invention relates to apparatus and methods for protecting against embolization during vascular interventions, such as carotid artery angioplasty and endarterectomy. More particularly, the apparatus and methods of the present invention induce substantially continuous retrograde flow through the internal carotid artery during treatment during an interventional procedure, without significant blood loss.
BACKGROUND OF THE INVENTION
• Carotid artery stenoses typically manifest in the common carotid artery, internal carotid artery or external carotid artery as a pathologic narrowing of the vascular wall, for example, caused by the deposition of plaque, that inhibits normal blood flow. Endarterectomy, an open surgical procedure, traditionally has been used to treat such stenosis of the carotid artery.
• An important problem encountered in carotid artery surgery is that emboli may be formed during the course of the procedure, and these emboli can rapidly pass into the cerebral vasculature and cause ischemic stroke.
• In view of the trauma and long recuperation times generally associated with open surgical procedures, considerable interest has arisen in the endovascular treatment of carotid artery stenosis. In particular, widespread interest has arisen in transforming interventional techniques developed for treating coronary artery disease, such as angioplasty and stenting, for use in the carotid arteries. Such endovascular treatments, however, are especially prone to the formation of emboli.
• Such emboli may be created, for example, when an interventional instrument, such as a guide wire or angioplasty balloon, is forcefully passed into or through the stenosis, as well as after dilatation and deflation of the angioplasty balloon or stent deployment. Because such instruments are advanced into the carotid artery in the same direction as blood flow, emboli generated by operation of the instruments are carried directly to the brain by antegrade blood flow. Stroke rates after carotid artery stenting have widely varied in different clinical series, from as low as 4.4% to as high as 30%. One review of carotid artery stenting including data from twenty-four major interventional centers in Europe, North America, South America and Asia, had a combined initial failure and combined mortality/stroke rate of more than 7%. Cognitive studies and reports of intellectual changes after carotid artery stenting indicate that embolization is a common event causing subclinical cerebral damage.
• Several previously known apparatus and methods attempt to remove emboli formed during endovascular procedures by trapping or suctioning the emboli out of the vessel of interest. These previously known systems, however, provide less than optimal solutions to the problems of effectively removing emboli.
• Solano et al. U.S. Pat. No. 4,921,478 describes cerebral angioplasty methods and devices wherein two concentric shafts are coupled at a distal end to a distally-facing funnel-shaped structure. A lumen of the innermost shaft communicates with an opening in the funnel-shaped structure at the distal end, and is open to atmospheric pressure at the proximal end. In use, the funnel-shaped structure is deployed proximally (in the direction of flow) of a stenosis, occluding antegrade flow. An angioplasty balloon catheter is passed through the innermost lumen and into the stenosis, and then inflated to dilate the stenosis. The patent states that when the angioplasty balloon is deflated, a pressure differential between atmospheric pressure and the blood distal to the angioplasty balloon causes a reversal of flow in the vessel that flushes any emboli created by the angioplasty balloon through the lumen of the innermost catheter.
• While a seemingly elegant solution to the problem of emboli removal, several drawbacks of the device and methods described in the Solano et al. patent seem to have lead to abandonment of that approach. Chief among these problems is the inability of that system to generate flow reversal during placement of the guide wire and the angioplasty balloon across the stenosis. Because flow reversal does not occur until after deflation of the angioplasty balloon, there is a substantial risk that any emboli created during placement of the angioplasty balloon will travel too far downstream to be captured by the subsequent flow reversal. It is expected that this problem is further compounded because only a relatively small volume of blood is removed by the pressure differential induced after deflation of the angioplasty balloon.
• Applicant has determined another drawback of the method described in the Solano patent: deployment of the funnel-shaped structure in the common carotid artery (“CCA”) causes reversal of flow from the external carotid artery (“ECA”) into the internal carotid artery (“ICA”). Consequently, when a guide wire or interventional instrument is passed across a lesion in either the ECA or ICA, emboli dislodged from the stenosis are introduced into the blood flow and carried into the cerebral vasculature via the ICA.
• The insufficient flow drawback identified for the system of the Solano patent is believed to have prevented development of a commercial embodiment of the similar system described in EP Publication No. 0 427 429. EP Publication No. 0 427 429 describes use of a separate balloon to occlude the ECA prior to crossing the lesion in the ICA. However, like Solano, that publication discloses that flow reversal occurs only when the dilatation balloon in the ICA is deflated.
• Chapter 46 ofInterventional Neuroradiology: strategies and practical techniques(J. J. Connors & J. Wojak, 1999), published by Saunders of Philadelphia, Pa., describes using a coaxial balloon angioplasty system for patients having proximal ICA stenoses. In particular, a small, deflated occlusion balloon on a wire is introduced into the origin of the ECA, and a guide catheter with a deflated occlusion balloon is positioned in the CCA just proximal to the origin of the ECA. A dilation catheter is advanced through a lumen of the guide catheter and dilated to disrupt the stenosis. Before deflation of the dilation catheter, the occlusion balloons on the guide catheter and in the ECA are inflated to block antegrade blood flow to the brain. The dilation balloon then is deflated, the dilation catheter is removed, and blood is aspirated from the ICA to remove emboli.
• Applicant has determined that cerebral damage still may result from the foregoing previously known procedure, which is similar to that described in EP Publication No. 0 427 429, except that the ICA is occluded prior to the ECA. Consequently, both of these previously known systems and methods suffer from the same drawback—the inability to generate flow reversal at sufficiently high volumes during placement of the guide wire and dilation catheter across the stenosis. Both methods entail a substantial risk that any emboli created during placement of the balloon will travel too far downstream to be captured by the flow reversal.
• Applicants note, irrespective of the method of aspiration employed with the method described in the foregoingInterventional Neuroradioloqyarticle, substantial drawbacks are attendant. If, for example, natural aspiration is used (i.e., induced by the pressure gradient between the atmosphere and the artery), then only a relatively small volume of blood is expected to be removed by the pressure differential induced after deflation of the angioplasty balloon. If, on the other hand, an external pump is utilized, retrieval of these downstream emboli may require a flow rate that cannot be sustained for more than a few seconds, resulting insufficient removal of emboli.
• Furthermore, with the dilation balloon in position, the occlusion balloons are not inflated until after inflation of the dilation balloon. Microemboli generated during advancement of the dilation catheter into the stenosed segment may therefore be carried by antegrade blood flow into the brain before dilation, occlusion, and aspiration are even attempted.
• Imran U.S. Pat. No. 5,833,650 describes a system for treating stenoses that comprises three concentric shafts. The outermost shaft includes a proximal balloon at its distal end that is deployed proximal of a stenosis to occlude antegrade blood flow. A suction pump then draws suction through a lumen in the outermost shaft to cause a reversal of flow in the vessel while the innermost shaft is passed across the stenosis. Once located distal to the stenosis, a distal balloon on the innermost shaft is deployed to occlude flow distal to the stenosis. Autologous blood taken from a femoral artery using an extracorporeal blood pump is infused through a central lumen of the innermost catheter to provide continued antegrade blood flow distal to the distal balloon. The third concentric shaft, which includes an angioplasty balloon, is then advanced through the annulus between the innermost and outermost catheters to dilate the stenosis.
• Like the device of the Solano patent, the device of the Imran patent appears to suffer the drawback of potentially dislodging emboli that are carried into the cerebral vasculature. In particular, once the distal balloon of Imran's innermost shaft is deployed, flow reversal in the vasculature distal to the distal balloon ceases, and the blood perfused through the central lumen of the innermost shaft establishes antegrade flow. Importantly, if emboli are generated during deployment of the distal balloon, those emboli will be carried by the perfused blood directly into the cerebral vasculature, and again pose a risk of ischemic stroke. Moreover, there is some evidence that reperfusion of blood under pressure through a small diameter catheter may contribute to hemolysis and possible dislodgment of emboli.
• In applicant's co-pending U.S. patent application Ser. No. 09/333,074, filed Jun. 14, 1999, which is incorporated herein by reference, applicant described the use of external suction to induce regional reversal of flow. That application further described that intermittently induced regional flow reversal overcomes the drawbacks of naturally-aspirated systems such as described hereinabove. However, the use of external suction may in some instances result in flow rates that are too high to be sustained for more than a few seconds. In addition, continuous use of an external pump may result in excessive blood loss, requiring infusion of non-autologous blood and/or saline that causes hemodilution, reduced blood pressure, or raise related safety issues.
• In view of these drawbacks of the previously known emboli removal systems, it would be desirable to provide methods and apparatus for removing emboli from within the carotid arteries during interventional procedures, such as angioplasty or carotid stenting, that reduce the risk that emboli are carried into the cerebral vasculature.
• It also would be desirable to provide methods and apparatus for removing emboli from within the carotid arteries during interventional procedures, such as angioplasty or carotid stenting, that provide substantially continuous retrograde blood flow from the treatment zone, thereby reducing the risk that emboli are carried into the cerebral vasculature.
• It further would be desirable to provide emboli removal methods and apparatus that prevent the development of reverse flow from the ECA and antegrade into the ICA once the CCA has been occluded, thereby enhancing the likelihood that emboli generated by a surgical or interventional procedure are effectively removed from the vessel.
• It also would be desirable to provide methods and apparatus that allow for placement of an interventional device so that retrograde flow may be achieved in the treatment vessel prior to having a guide wire cross the lesion.
• It also would be desirable to provide methods and apparatus for removing emboli during an angioplasty or carotid stenting procedure that enable filtering of emboli and reduced blood loss.
SUMMARY OF THE INVENTION
• In view of the foregoing, it is an object of this invention to provide methods and apparatus for removing emboli from within the carotid arteries during interventional procedures, such as angioplasty or carotid stenting, that reduce the risk that emboli are carried into the cerebral vasculature.
• It also is an object of the present invention to provide methods and apparatus for removing emboli from within the carotid arteries during interventional procedures, such as angioplasty or carotid stenting, that provide substantially continuous retrograde blood flow from the treatment zone, thereby reducing the risk that emboli are carried into the cerebral vasculature.
• It is another object of the present invention to provide emboli removal methods and apparatus that prevent the development of reverse flow between the ECA and ICA once the common carotid artery has been occluded, thereby enhancing the likelihood that emboli generated by a surgical or interventional procedure are effectively removed from the vessel.
• It is still a further object of the present to provide methods and apparatus that allow for placement of an interventional device so that retrograde flow may be achieved in the treatment vessel prior to having a guide wire cross the lesion.
• It is yet another object of the present invention to provide methods and apparatus for removing emboli during an angioplasty or carotid stenting procedure that enable filtering of emboli and reduced blood loss.
• The foregoing objects of the present invention are accomplished by providing interventional apparatus comprising an arterial catheter, an occlusion element disposed on a guide wire, a venous return sheath, and optionally a blood filter. The arterial catheter has proximal and distal ends, an aspiration lumen extending therethrough, an occlusion element disposed on the distal end, and a hemostatic port and blood outlet port disposed on the proximal end that communicate with the aspiration lumen. The aspiration lumen is sized so that an interventional instrument, e.g., an angioplasty catheter or stent delivery system, may be readily advanced therethrough to the site of a stenosis in either the ECA (proximal to the occlusion element) or the ICA.
• In accordance with the principles of the present invention, the arterial catheter is disposed in the CCA proximal of the ICA/ECA bifurcation, the occlusion element on the guide wire is disposed in the ECA to occlude flow reversal from the ECA to the ICA, and the blood outlet port of the arterial catheter is coupled to the venous return sheath, with or without the blood filter disposed therebetween. Higher arterial than venous pressure, especially during diastole, permits substantially continuous flow reversal in the ICA during the procedure (other than when a dilatation balloon is inflated), thereby flushing blood containing emboli from the vessel. The blood is filtered and reperfused into the body through the venous return sheath.
• In an alternative embodiment, the occlusion element disposed on the guide wire may be omitted, and replaced with apparatus comprising a self-expanding element having proximal and distal ends, a retrieval wire coupled to the proximal end and an atraumatic tip coupled to the distal end. In this embodiment, a dilator having a lumen may be disposed within the aspiration lumen of the catheter so that the occlusion element is provided in a contracted state within the lumen of the dilator. The occlusion element then is ejected from the dilator and self-expands to occlude the ECA. The dilator then is removed from the aspiration lumen of the catheter, and the distal end of the catheter is re-positioned in the CCA proximal of the carotid bifurcation. Flow reversal is induced in the ICA, as described above, and the self-expanding occlusion element may be contracted using the retrieval wire provided.
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:
• FIGS. 1A and 1B are schematic views of previously known emboli protection systems;
• FIG. 2 is a schematic view of an emboli protection system in accordance with principles of the present invention;
• FIGS. 3A-3D are, respectively, a schematic view of apparatus in accordance with a first embodiment of the present invention, detailed side and sectional views of the distal end of an interventional device of the present invention, and a cross-sectional view of an interventional device of the present invention;
• FIGS. 4A and 4B are views of the distal end of an alternative interventional device suitable for use in the system of the present invention;
• FIGS. 5A-5D illustrate a method of using the system ofFIG. 3 in accordance with the principles of the present invention;
• FIGS. 6A-6C are, respectively, a schematic view and cross-sectional views of the proximal and distal ends of a catheter of an alternative embodiment of the present invention;
• FIGS. 7A-7B depict features of the self-expanding occlusion element ofFIG. 6; and
• FIGS. 8A-8D illustrate a method of using the system ofFIG. 6 in accordance with the principles of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
• Referring toFIGS. 1A and 1B, drawbacks of previously known emboli removal catheters are described with reference to performing percutaneous angioplasty of stenosis S in common carotid artery CCA.
• With respect toFIG. 1A, drawbacks associated with naturally-aspirated emboli removal systems, such as described in the above-mentioned patent to Solano and European Patent Publication, are described. No flow reversal is induced by those systems until afterballoon10 of angioplasty catheter11 first is passed across the stenosis, inflated, and then deflated. However, applicant has determined that oncemember15 ofemboli removal catheter16 is inflated, flow within the ECA reverses and provides antegrade flow into the ICA, due to the lower hemodynamic resistance of the ICA. Consequently, emboli E generated while passingguide wire20 or catheter11 across stenosis S may be carried irretrievably into the cerebral vasculature, before flow in the vessel is reversed and directed into the aspiration lumen ofemboli removal catheter16 by opening the proximal end of the aspiration lumen to atmospheric pressure. Furthermore, natural-aspiration may not remove an adequate volume of blood to retrieve even those emboli that have not yet been carried all the way into the cerebral vasculature.
• InFIG. 1B,system17 described in the above-mentioned patent to Imran is shown. As described hereinabove, deployment ofdistal balloon18, and ejection of blood out of the distal end of the inner catheter, may dislodge emboli from the vessel wall distal toballoon18. The introduction of antegrade flow throughinner catheter19 is expected only to exacerbate the problem by pushing the emboli further into the cerebral vasculature. Thus, while the use of positive suction in the Imran system may remove emboli located in the confined treatment field defined by the proximal and distal balloons, such suction is not expected to provide any benefit for emboli dislodged distal ofdistal balloon18.
• Referring now toFIG. 2, apparatus and methods in accordance with the present invention are described.Apparatus30 comprisescatheter31 having an aspiration lumen andocclusion element32, and guidewire35 havinginflatable balloon36 disposed on its distal end. In accordance with the principles of the present invention, antegrade blood flow is stopped when bothocclusion element32 in the CCA andinflatable balloon36 are deployed. Furthermore, the aspiration lumen ofcatheter31 is connected to a venous return sheath (described hereinbelow), disposed, for example, in the patient's femoral vein. In this manner a substantially continuous flow of blood is induced between the treatment site and the patient's venous vasculature. Because flow through the artery is towardscatheter31, any emboli dislodged by advancing a guide wire orangioplasty catheter33 across stenosis S causes the emboli to be aspirated bycatheter31.
• Unlike the previously known naturally-aspirated systems, the present invention provides substantially continuous retrograde blood flow through the ICA while preventing blood from flowing retrograde in the ECA and antegrade into the ICA, thereby preventing emboli from being carried into the cerebral vasculature. Because the apparatus and methods of the present invention “recycle” emboli-laden blood from the arterial catheter through the blood filter and to the venous return sheath, the patient experiences significantly less blood loss.
• Referring now toFIG. 3A,embolic protection apparatus40 constructed in accordance with the principles of the present invention is described.Apparatus40 comprisesarterial catheter41,guide wire45,venous return sheath52,tubing49 andoptional blood filter50.
• Catheter41 includesdistal occlusion element42, proximalhemostatic port43, e.g., a Touhy-Borst connector,inflation port44, andblood outlet port48.Guide wire45 includesballoon46 that is inflated viainflation port47.Tubing49 couplesblood outlet port48 to filter50 andblood inlet port51 ofvenous return sheath52.
• Guide wire45 andballoon46 are configured to pass throughhemostatic port43 and the aspiration lumen of catheter41 (seeFIGS. 3C and 3D), so that the balloon may be advanced into and occlude theECA. Port43 and the aspiration lumen ofcatheter41 are sized to permit additional interventional devices, such as angioplasty balloon catheters, atherectomy devices and stent delivery systems to be advanced through the aspiration lumen whenguide wire45 is deployed.
• Guide wire45 preferably comprises a small diameter flexible shaft having an inflation lumen that couplesinflatable balloon46 toinflation port47.
• Inflatable balloon46 preferably comprises a compliant material, such as described hereinbelow with respect toocclusion element42 ofemboli removal catheter41.
• Venous return sheath52 includeshemostatic port53,blood inlet port51 and a lumen that communicates withports53 and51 andtip54.
• Venous return sheath52 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 sheath52 may be lengthened to engage either end offilter50 or each other.
• With respect toFIGS. 3B and 3C,distal occlusion element42 comprises expandable bell or pear-shapedballoon55. In accordance with manufacturing techniques that 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 bell-shape when inflated.Balloon55 is affixed todistal end56 ofcatheter41, 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. In a preferred embodiment ofcatheter41, the diameter oflumen58 is about 7 Fr, and the outer diameter of the catheter is about 9 Fr.
• Referring now toFIGS. 4A and 4B, an alternative embodiment ofocclusion element42 of the system ofFIG. 3A is described. InFIGS. 4A and 4B,occlusion element42 ofemboli removal catheter41 comprises self-expandingwire basket65 covered withelastomeric polymer66, such as latex, polyurethane or polyisoprene. Alternatively, a tightly knit self-expanding wire mesh may be used, with or without an elastomeric covering.
• Catheter41 is contained withinmovable sheath67.Catheter41 is inserted transluminally withsheath67 in a distalmost position, and afterbasket65 has been determined to be in a desired position proximal to a stenosis,sheath67 is retracted proximally to causebasket65 to deploy. Upon completion of the procedure,basket65 is again collapsed withinsheath67 by moving the sheath to its distalmost position. Operation of the system ofFIG. 3A using the emboli removal catheter ofFIGS. 4A and 4B is similar to that described hereinbelow forFIGS. 5A-5D, except that the occlusion element self-expands whensheath67 is retracted, rather than by infusing an inflation medium to balloon55.
• Referring now toFIGS. 5A-5D, use of the apparatus ofFIG. 3 in accordance with the methods of the present invention is described. InFIG. 5, stenosis S is located in internal carotid artery ICA above the bifurcation between the ICA and the external carotid artery ECA. In a first step,guide wire80 is inserted into a patient's arterial vasculature and a distal end ofguide wire80 preferably is disposed just proximal of the carotid bifurcation, as shown inFIG. 5A. A dilator (not shown), which is disposed withincatheter41, then may be inserted overguide wire80 to advancecatheter41 to a position proximal of stenosis S, as shown inFIG. 5A, and the dilator may be removed.Balloon55 ofdistal occlusion element42 then is inflated viainflation port44, preferably using a radiopaque contrast solution, and guidewire80 may be removed. Onceballoon55 ofdistal occlusion element42 is inflated, flow within the ECA reverses and provides antegrade flow into the ICA, as shown inFIG. 5A, due to the lower hemodynamic resistance of the ICA.
• Venous return sheath52 then is introduced into the patient's femoral vein, either percutaneously or via a surgical cut-down.Filter50 then is coupled betweenblood outlet port48 ofcatheter41 andblood inlet port51 ofvenous return sheath52 usingtubing49, and any air is removed from the line. Once this circuit is closed, negative pressure in the venous sheath during diastole will establish a low rate continuous flow of blood throughaspiration lumen58 ofcatheter41, to the patient's vein viavenous return sheath52.
• Guide wire45 andballoon46 then may be advanced throughaspiration lumen58. Whenballoon46 is disposed within the ECA, as determined, e.g., using a fluoroscope and a radiopaque inflation medium injected intoballoon46,balloon46 is inflated. The deployment ofballoon46 in the ECA, in conjunction with the negative pressure in the venous sheath during diastole, will established a retrograde flow dynamic in the ICA, as shown inFIG. 5B.
• This continuous retrograde flow in the ICA due to the difference between venous pressure and arterial pressure will continue throughout the interventional procedure. Specifically, blood passes throughaspiration lumen58 andblood outlet port48 ofcatheter41, throughbiocompatible tubing49 to filter50, and intoblood inlet port51 ofvenous return sheath52, where it is reperfused into the remote vein. Filtered emboli collect infilter50 and may be studied and characterized upon completion of the procedure.
• Continuous blood flow (except during inflation of any dilatation instruments) with reperfusion in accordance with the present invention provides efficient emboli removal with significantly reduced blood loss. Alternatively, filter50 may be omitted, in which case emboli removed from the arterial side will be introduced into the venous side, and eventually captured in the lungs. Because of a low incidence of septal defects, which could permit such emboli to cross-over to the left ventricle, the use offilter50 is preferred.
• Referring toFIG. 5C, an interventional instrument, such as conventionalangioplasty balloon catheter71 havingballoon72, is loaded throughhemostatic port43 andaspiration lumen58 and positioned within the stenosis, preferably viaguide wire73.Hemostatic port43 is closed andinstrument71 is actuated to disrupt the plaque forming stenosis S.
• As seen inFIG. 5D, upon completion of the angioplasty portion of theprocedure using catheter71,balloon72 is deflated. Throughout the procedure, except when the dilatation balloon is fully inflated, the pressure differential between the blood in the ICA and the venous pressure causes blood in the ICA to flow in a retrograde direction intoaspiration lumen58 ofemboli removal catheter41, thereby flushing any emboli from the vessel. The blood is filtered and reperfused into the patient's vein.
• As set forth above, the method of the present invention protects against embolization, first, by preventing the reversal of blood flow from the ECA to the ICA whendistal occlusion element42 is inflated, and second, by providing continuous, low volume blood flow from the carotid artery to the remote vein in order to filter and flush any emboli from the vessel and blood stream. Advantageously, the method of the present invention permits emboli to be removed with little blood loss, because the blood is filtered and reperfused into the patient. Furthermore, continuous removal of blood containing emboli prevents emboli from migrating too far downstream for aspiration.
• Referring now toFIG. 6,apparatus240 constructed in accordance with the present invention is described.Apparatus240 is an alternative embodiment ofapparatus40 described hereinabove and comprisesarterial catheter241 having proximal and distal ends,distal occlusion element242 disposed on the distal end, proximalhemostatic port243,inflation port244 andblood outlet port248. Self-expandingocclusion element246 having proximal and distal ends preferably comprisesnon-expanding occlusion base256 disposed at the proximal end, whereinocclusion base256 comprisesproximal taper269.Occlusion element246 is coupled toretrieval wire247 at the proximal end andatraumatic tip245 at the distal end, e.g., by affixingretrieval wire247 toproximal taper269 ofocclusion base256 and affixingatraumatic tip245 to a distal end ofocclusion base256, as shown inFIG. 6A.Biocompatible tubing249 couplesblood outlet port248 to filter250 and toblood inlet port251 ofvenous return sheath252.Arterial catheter241,venous return sheath252 andtubing249 are constructed as described hereinabove, except as noted below.
• Catheter241 comprisesaspiration lumen258, as shown inFIG. 6B, which is sized to permit interventional devices, such as angioplasty balloon catheters, atherectomy devices and stent delivery systems to be advanced throughport243 and the aspiration lumen.Retrieval wire lumen264 is sized to permit longitudinal movement ofretrieval wire247 ofocclusion element246.Retrieval wire lumen264 spans from the proximal end ofcatheter241 to a location just proximal of the distal end, e.g., about 1 to 2 cm proximal of the distal end ofcatheter241. At this location,retrieval wire lumen264 merges withaspiration lumen258 to formchannel265, as shown inFIG. 6C.
• Referring toFIG. 7, deployment ofocclusion element246 is described.Occlusion element246 initially is provided in a contracted state, as shown inFIG. 7A. In the contracted state,occlusion element246 is disposed within a lumen ofdilator270, which in turn is disposed withinaspiration lumen258 ofcatheter241.Dilator270 comprises proximal and distal ends, withocclusion element246 being positioned within a slot in the distal end. The distal end ofdilator270 tapers and extends distal tocatheter241, as shown inFIG. 7A.Atraumatic tip245 ofocclusion element246 extends distal todilator270 and facilitates guidance of the device through a patient's vasculature.
• Push member272 having proximal and distal ends is configured for longitudinal movement within the lumen ofdilator270. During delivery ofcatheter241, the distal end ofpush member272 preferably abutsocclusion base256 ofocclusion element246, while the proximal end ofpush member272 may be manipulated by a physician.Dilator270 comprisesslot271 disposed at the distal end.Slot271 allowsretrieval wire247 to extend from a distal point in which it is coupled toocclusion base256, to a proximal point in which it entersretrieval wire lumen264, as shown inFIG. 7A.
• Upon positioning the distal end ofcatheter241 at a selected location,push member272 is held stationary whiledilator270 is retracted proximally, so thatocclusion element246 effectively is no longer constrained within the lumen ofdilator270. This causesocclusion element246 to self-expand to a predetermined shape, as shown inFIG. 7B.Occlusion element246 is sized to occlude flow in the external carotid artery in this deployed state.
• Dilator slot271 allowsretrieval wire247 to move freely during the deployment ofocclusion element246. After deployment ofocclusion element246,dilator270 and pushmember272 are removed from withinaspiration lumen258, as shown inFIG. 7B.Catheter241 then may be positioned separately fromocclusion element246, as described hereinbelow with respect toFIG. 8, and may be used to deliver other interventional apparatus, such as angioplasty catheters or stent delivery systems.
• At the completion of the interventional procedure,occlusion element246 is contracted by proximally retractingretrieval wire247.Occlusion element246 is retrieved when the proximal load exerted onretrieval wire247 exceeds the frictional forces betweenocclusion element246 and the external carotid artery wall. Afterocclusion element246 is contracted,occlusion base256,occlusion element246 andatraumatic tip245 may be retracted partially or fully intoaspiration lumen258.Channel265 ofFIG. 6C may be used to provide a transition at the distal end ofcatheter241 so thatocclusion element246 is effectively guided intoaspiration lumen258 whenretrieval wire247 is retracted proximally. In effect, this allowsocclusion element246 to be contained within at least a distal portion ofcatheter241, to allow for safe removal ofcatheter241.
• Referring toFIG. 8, method steps for using the apparatus ofFIGS. 6-7 to treat carotid artery disease is provided. InFIG. 8, stenosis S is located in the ICA above the carotid bifurcation. In a first step,catheter241 is inserted, either percutaneously and transluminally or via a surgical cut-down, to a position proximal of stenosisS. Occlusion element246 is disposed within a lumen at the distal end ofdilator270, as described inFIG. 7A, andatraumatic tip245 is used to guidecatheter241. The distal end ofcatheter241 preferably is positioned within the ECA, as shown inFIG. 8A, so thatocclusion element246 will be deployed into the ECA.
• Push member272 ofFIG. 7A then is held stationary whiledilator270 is retracted proximally, so thatocclusion element246 is no longer constrained bydilator270.Occlusion element246 then self-expands to occlude flow in the ECA, as shown inFIG. 8B.Dilator270 and pushmember272 then are removed from withinaspiration lumen258, andcatheter241 is retracted to a location just proximal of the carotid bifurcation, as shown inFIG. 8B.Distal occlusion element242 ofcatheter241 then may be inflated viainflation port244 to occlude antegrade flow in the CCA.
• Venous return sheath252 may be introduced into the patient's femoral vein, either percutaneously or via a surgical cut-down, and filter250 may be coupled betweenblood outlet port248 ofcatheter241 andblood inlet port251 ofvenous return sheath252 usingtubing249. Once this circuit is closed, negative pressure in the venous sheath establishes a continuous retrograde flow of blood throughaspiration lumen258 ofcatheter241, as shown inFIG. 8B, to the patient's vein viavenous return sheath252. Alternatively,venous return sheath252 may be omitted, and the proximal end ofcatheter241 connected to a receptacle to collect blood aspirated throughaspiration lumen258.
• Referring toFIG. 8C, withdistal occlusion element242 inflated and a retrograde flow established in the ICA, an interventional instrument, such as conventionalangioplasty balloon catheter281 havingballoon282, is loaded throughhemostatic port243 andaspiration lumen258 and positioned within stenosis S, preferably viaguide wire283.Hemostatic port243 is closed andinstrument281 is actuated to disrupt stenosis S.
• As shown inFIG. 8D, upon completion of the angioplasty portion of theprocedure using catheter281,balloon282 is deflated. Throughout the procedure, except when the dilatation balloon is fully inflated, the pressure differential between the blood in the ICA and the venous pressure causes blood in the ICA to flow in a retrograde direction and intoaspiration lumen258 ofemboli removal catheter241, thereby flushing any emboli E from the vessel. Upon satisfactory removal of emboli,occlusion element246 is contracted by proximally retractingretrieval wire247.Occlusion element246 still further may be contracted when it contacts the distal end ofcatheter241. Whenocclusion element246 has been contracted, it then may be retracted either partially or fully intoaspiration lumen258 ofcatheter241 viachannel265.Distal occlusion element242 ofcatheter241 then is deflated and the apparatus is removed from the patient's vessel.
• 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. The appended claims are intended to cover all such changes and modifications that fall within the true spirit and scope of the invention.

Claims (5)

1. A method of delivering an interventional instrument for treating a stenosis in an internal carotid artery comprising:

a) inserting an occlusion mechanism having a distal occlusion member and a balloon into a person's vasculature;

b) positioning the distal occlusion member to a desired position in the common carotid artery and the balloon to a desired position in the external carotid artery; and

c) operating the distal occlusion member and the balloon to occlude the external carotid artery and the central carotid artery.

2. A method according toclaim 1, wherein said occlusion mechanism further comprises a catheter having a proximal end and a distal end, an aspiration lumen extending therethrough, and said distal occlusion member positioned at said distal end of said catheter.

3. A method according toclaim 2, further comprising: aspirating blood through said aspiration lumen.

4. A method according toclaim 2, further comprising: inducing reverse flow to cause blood and emboli to flow into the aspiration lumen of the catheter.

5. A method according toclaim 4 wherein inducing reverse flow further comprises:

a) providing a venous return sheath having a proximal end and a distal end, a lumen extending therethrough, and a blood inlet port coupled to the lumen; and

b) causing blood flow between the aspiration lumen of the catheter and the blood inlet port of the venous return sheath to induce reverse flow.

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