Abstract:
Improved methods and apparatus for capturing emboli and subsequently removing or immobilizing the captured emboli are described. Emboli can be captured within a blood vessel and can be withdrawn to a position exterior to the blood vessel. Some filters can remain within a blood vessel yet direct emboli to a position exterior to the blood vessel.

Description:
TECHNICAL FIELD  
       [0001]     The invention relates generally to capturing intravascular emboli.  
       BACKGROUND  
       [0002]     Heart and vascular disease are major problems in the United Sates and throughout the world. Conditions such as atherosclerosis result in blood vessels becoming blocked or narrowed. This blockage can result in lack of oxygenation of the heart, which has significant consequences since the heart muscle must be well oxygenated in order to maintain its blood pumping action.  
         [0003]     Occluded, stenotic or narrowed blood vessels may be treated with a number of relatively non-invasive medical procedures including percutaneous transluminal angioplasty (PTA), percutaneous transluminal coronary angioplasty (PTCA), and atherectomy. Angioplasty techniques such as PTA and PTCA typically involve the use of a balloon catheter. The balloon catheter is advanced over a guidewire such that the balloon is positioned adjacent a stenotic lesion. The balloon is then inflated, and the restriction in the vessel is opened. During an atherectomy procedure, the stenotic lesion may be mechanically or otherwise cut away from the blood vessel wall using an atherectomy catheter.  
         [0004]     During procedures such as angioplasty and atherectomy procedures, as well during other operations and even as a result of natural events, embolic debris can be separated from the wall of the blood vessel. If this debris enters the circulatory system, it can block other vascular regions including the neural and pulmonary vasculature. During angioplasty procedures, stenotic debris may also break loose due to manipulation of the blood vessel.  
         [0005]     Because of this debris, a number of devices such as intravascular filters have been developed to filter out debris. A need remains for improved methods of capturing and removing intravascular emboli.  
       SUMMARY  
       [0006]     The present invention is directed to improved methods and techniques for capturing emboli and subsequently removing or immobilizing the captured emboli. The present invention is also directed to a filter that is adapted to capture emboli and direct emboli away from the vessel in which the filter is deployed.  
         [0007]     Accordingly, an example embodiment of the invention can be found in a method of removing emboli from a blood vessel that has a vessel wall that defines an interior of the blood vessel. Blood can flow through the interior of the blood vessel. A pocket is provided that is exterior to the blood vessel but in fluid communication with the interior of the blood vessel. A portion of the blood flowing through the interior of the blood vessel may be diverted such that emboli within the blood flow are carried into the pocket.  
         [0008]     Another example embodiment of the invention can be found in a method of removing emboli from a blood vessel that includes a lumen. A filter having an open end and a tapered end may be positioned within the lumen such that the open end is positioned upstream and the tapered end is positioned downstream. The tapered end of the filter may be in fluid communication with a tube leading to a position exterior to the blood vessel. Emboli may be captured within the filter and can be passed through the tube and thus can be passed to a position exterior to the blood vessel.  
         [0009]     Another example embodiment of the invention can be found in an intravascular filter that includes an open end that is adapted to fit within a blood vessel, a tapered end and a tube that is in fluid communication with the tapered end. A valve may be positioned at the tapered end.  
         [0010]     Another example embodiment of the invention can be found in a method of removing emboli from a blood vessel. The blood vessel includes a vessel wall that defines an interior of the blood vessel having blood flowing therethrough. An external port can be provided that is exterior to the blood vessel but in fluid communication with the interior of the blood vessel. A one-way valve that permits flow from the interior of the blood vessel into the external port but does not permit flow from the external port to the interior of the blood vessel can be provided. A temporal blood pressure increase may permit blood flow through the one-way valve such that emboli within the blood flow are carried into the external portion.  
         [0011]     Another example embodiment of the invention can be found in a method of removing emboli from a vein that is transporting blood back from a patient&#39;s leg. A filter can be positioned within the vein. Emboli can be captured within the filter and can be shunted into an artery that carries blood into the leg. As a result, the captured emboli are harmlessly ensnared within the patient&#39;s feet.  
         [0012]     The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures, Detailed Description and Examples which follow more particularly exemplify these embodiments.  
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0013]     The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:  
         [0014]      FIG. 1  is a schematic illustration of a method in accordance with an embodiment of the invention;  
         [0015]      FIG. 2  is a schematic illustration of a method in accordance with an embodiment of the invention;  
         [0016]      FIG. 3  is a schematic illustration of a method in accordance with an embodiment of the invention;  
         [0017]      FIG. 4  is a schematic illustration of a method in accordance with an embodiment of the invention;  
         [0018]      FIG. 5  is a schematic illustration of a method in accordance with an embodiment of the invention;  
         [0019]      FIG. 6  is a schematic illustration of a method in accordance with an embodiment of the invention;  
         [0020]      FIG. 7  is a schematic illustration of a method in accordance with an embodiment of the invention;  
         [0021]      FIG. 8  is a schematic illustration of a method in accordance with an embodiment of the invention;  
         [0022]      FIG. 9  is a schematic illustration of a method in accordance with an embodiment of the invention; and  
         [0023]      FIG. 10  is a schematic illustration of a method in accordance with an embodiment of the invention. 
     
    
       [0024]     While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.  
       DETAILED DESCRIPTION  
       [0025]     For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification.  
         [0026]     All numeric values are herein assumed to be modified by the term “about”, whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value, i.e., having the same function or result. In many instances, the term “about” may include numbers that are rounded to the nearest significant figure.  
         [0027]     As used in this specification and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and in the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.  
         [0028]     The following description should be read with reference to the drawings, in which like elements in different drawings are numbered in like fashion. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. Although examples of construction, dimensions, and materials are illustrated for the various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized.  
         [0029]     Turning now to  FIG. 1 , a pocket  10  has been formed proximate to a blood vessel  12  having a vessel wall  14 . In some embodiments, an aperture  16  can be formed within the vessel wall  14  using any suitable technique. In the illustrated embodiment, the pocket  10  can be formed from a piece of any suitable material that can be passed through the blood vessel  12  and pushed at least partially through the aperture  16  to form the pocket  10 . In some cases, the pocket  10  may be formed from material that is inserted into aperture  16  from a position exterior to the vessel wall  14 .  
         [0030]     In some instances, the pocket  10  may be formed from any suitable metallic, polymeric, biological or even autogenous vascular material, i.e. material grafted from another location with the patient&#39;s vasculature. The piece of material used to form the pocket  10  can be any suitable fluid-tight mesh or solid polymeric layer. In other embodiments, the pocket  10  can be rigidly formed and can include a narrowed portion adapted to fit through the aperture  16 .  
         [0031]     As illustrated, a diverter  18  is positioned near to but just downstream of the aperture  16 . The diverter  18  functions to divert at least a portion of blood flow into the pocket  10  such that at least some of the emboli that may be present within the blood flow are captured within the pocket  10  as captured emboli  20 . The diverter  18  may be formed of any suitable metallic, polymeric, biological or even autogenous vascular material. The diverter  18  can be positioned within the blood vessel  12  by inserting the diverter  18  through the vessel wall  14  from a position exterior to the blood vessel  12 . In some embodiments, the diverter  18  can be formed by a portion of a filter positioned within the blood vessel  12 . In some cases, the diverter  18  can be stationary while in other instances the diverter  18  may be configured to move back and forth, much like an automotive windshield wiper, to better direct emboli into the pocket  10 .  
         [0032]     Eventually, the pocket  10  may become full or at least substantially full with captured emboli  20 . In  FIG. 2 , a syringe  22  is inserted into the pocket  10  and is used to remove the captured emboli  20  from the pocket  10 . In other embodiments, any suitable source of suction, such as an aspiration needle fluidly connected to a vacuum pump, can be used. In some instances, the syringe  22  may be used to inject a thrombolytic agent to dissolve or otherwise lyse the captured emboli  20 .  
         [0033]      FIG. 3  illustrates an embodiment in which the diverter and pocket are integrally formed. Blood vessel  12  includes a vessel wall  14  having an aperture  16 , as before. An assembly  24  is positioned within the blood vessel  12  such that a filter portion  26  is located within blood vessel  12  and thus is subjected to blood flow while a pocket portion  28  extends through the aperture  16  and exterior to the blood vessel  12 . Part or all of the assembly  24  may be coated with a material designed to prevent clotting and perhaps to stimulate endothelial cell growth in an interior of the pocket portion  28 . Smooth muscle cell growth near the aperture  16  may be prevented by a suitable coating. An exemplary coating includes a combination of SIBS and PACLITAXEL™. SIBS, or poly(styrene-b-isobutylene-b-styrene), is commercially available from Boston Scientific Corporation under the tradename TRANSLUTE™. PACLITAXEL™ is a plant-derived antiproliferative agent.  
         [0034]     In some instances, the assembly  24  may be advanced through the blood vessel  12  and can be advanced through the aperture  16  to reach its operational position, as indicated. In some cases, however, the assembly  24  may be provided from exterior to the blood vessel  12 . The pocket portion  28  remaining outside the blood vessel  12  may be flood sealed. The filter portion  26  located within the blood vessel  12  may include self-unfolding hooks (not illustrated) to assure that the filter portion  26  is properly positioned.  
         [0035]     Blood flowing through the blood vessel  12  will encounter the filter portion  26 . Blood will pass through, but at least a portion of any emboli that may be present within the blood flow will be captured by the filter portion  26 . The filter portion  26  can be formed of any suitable filter mesh such that blood can pass through but potentially harmful emboli are captured. The captured emboli  30  pass into the pocket portion  28  and await removal in any suitable manner. Suction such as that described with respect to  FIG. 2  may be used to remove the captured emboli  30  from the pocket portion  28 .  
         [0036]     Turning now to  FIG. 4 , another embodiment is illustrated. Rather than inserting an artificial pocket as previously discussed, a pocket  32  is formed by weakening a portion of the blood vessel wall  14 . This can be done in any suitable manner, such as abrading away a portion of the vessel wall  14 , using a balloon catheter to stretch a portion of the vessel wall  14 , or perhaps chemically weakening a portion of the vessel wall  14 .  
         [0037]     Much as discussed with respect to  FIGS. 1 and 2 , emboli  34  can collect within the pocket  32 . Once the pocket  32  becomes full, at least a portion of the captured emboli  34  can be removed using a syringe  22  or any other suitable suction technique. In some cases, the captured emboli  34  can remain within the pocket  32 . In some instances, a thrombolytic agent may be injected into the pocket  32  to dissolve or otherwise lyse the captured emboli  34 .  
         [0038]      FIGS. 5-7  illustrate a particular method of forming a collection area. In  FIG. 5 , a balloon catheter  36  including a balloon  38  is positioned within the blood vessel  12 . A stent  40  is positioned over the balloon  38  as is known in the art. The stent  40  may be formed of any suitable material such as stainless steel. The stent  40  may include inner wires  42  that can be formed of any suitable material such as nitinol. In  FIG. 6 , the balloon  38  has been over-inflated, thereby expanding a portion  44  of the vessel wall  14 .  
         [0039]     Once the balloon  38  has been de-inflated, as shown in  FIG. 7 , the stent  40  remains in position while the inner wires  42  are allowed to fold inwards to form collection areas  46 . While not expressly illustrated, a reinforcing layer or member may be placed either interior to the portion  44  or exterior to the portion  44 . The reinforcing layer may prevent additional expansion of the portion  44 . In some cases, the reinforcing layer may prevent portion  44  from collapsing, or recoiling. Emboli  34  that collect within the collection areas  46  may be removed in any suitable manner such as discussed with respect to  FIGS. 2, 3  and  4 .  
         [0040]      FIG. 8  shows a particular embodiment having usefulness closer to a patient&#39;s heart. A blood vessel  48  has a vessel wall  50 . Blood vessel  48  is positioned proximate a valve  52  that controls blood flow between the right atrium and the right ventricle. A one-way valve  54  is positioned within the vessel wall  50  such that the one-way valve  54  is in communication with an external port  56 . The external port  56  can lead to a collection point within the patient or the external port  56  can lead to a position external to the patient. When the valve  52  closes, the resulting temporal increase in blood pressure causes blood to flow towards the one-way valve  54 . As a result, emboli present within the blood flow may be carried through the one-way valve  54  and into the external port  56 .  
         [0041]     Turning now to  FIG. 9 , another embodiment of the invention is illustrated. A filter  58  includes an open end  60  and a tapered end  62 . A valve  64  may be positioned at the tapered end  62  that is in communication with a tube  66 . The filter  64  is seen within a blood vessel  68  having a vessel wall  70 . The tube  66  can extend through an aperture  72  in the vessel wall  70  and can extend to a valve  74  that is positioned proximate a portion  76  of the patient&#39;s skin.  
         [0042]     At least a portion of any emboli present within the blood flow will be captured by the filter  58  and can pass through the valve  64  into the tube  66 . As a result, the captured emboli can be removed from the patient through valve  74  without removing the filter  58  from the patient.  
         [0043]      FIG. 10  illustrates a method of capturing and disposing of emboli present in a patient&#39;s leg  78 . The leg  78  includes a vein  80  carrying spent blood towards the heart and lungs and an artery  82  that carries replenished blood back into the leg  78 . Emboli traveling within the vein  80  can be captured by a filter  84 . The filter  84  can be any suitable intravascular filter as known in the art. A shunt  86  can be positioned between the vein  80  and the artery  82  such that any emboli captured within the filter  84  can be directed through the shunt  86  and into the artery  82 .  
         [0044]     In some instances, the blood pressure within the artery  82  may be higher than the blood pressure within the vein  80 . Consequently, a collection ball  88  may be disposed along the shunt  86 . A first one-way valve (not illustrated) within the collection ball  88  permits blood to exit the vein  80  and enter a collection volume within the collection ball  88 . A second one-way valve within the collection ball  88  permits blood to exit the collection volume and enter the artery  82 . The collection ball  88  may be disposed relatively close to the patient&#39;s skin so that squeezing or depressing the collection ball  88  can activate the first and second one-way valves. Captured emboli are carried downward through the artery  82  and can harmlessly collect in the patient&#39;s feet.  
         [0045]     The invention should not be considered limited to the particular examples described above, but rather should be understood to cover all aspects of the invention as set out in the attached claims. Various modifications, equivalent processes, as well as numerous structures to which the invention can be applicable will be readily apparent to those of skill in the art upon review of the instant specification.