Abstract:
A vascular catheter and method of use of the catheter for aiding in balloon angioplasty and stent placement procedures are disclosed. The vascular catheter has a retrieval catheter with an expanded distal portion. The expanded distal portion has aspiration holes which allow aspiration of embolic debris during recovery of the embolic filter. A guide sheath may be used to guide the retrieval catheter past a stent and into position for aspiration and retrieval of the filter after stent placement.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the benefit of U.S. Provisional Patent Ser. No. 60/741,215 filed Dec. 2, 2005. This application is a continuation-in-part application of U.S. patent application Ser. No. 10/348,137 filed Jan. 21, 2003, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/363,310 filed Mar. 12, 2002. All of these applications are herein incorporated by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a vascular catheter and more particularly relates to a vascular catheter for providing recovery of distal protection devices and aspiration of embolic debris created during an intervention of blood vessels.  
       BACKGROUND INFORMATION  
       [0003]     It is common practice today to open occluded or stenotic blood vessels by inserting a guide wire and then a catheter carrying a balloon shaped segment and inflating the balloon, which exerts a radial force to press stenosis outward against the wall of the blood vessel. This procedure is called balloon angioplasty. Frequently, an implantable metallic stent will also be used to provide greater strength at the stenotic portion of the blood vessel, and to provide longer-term patency.  
         [0004]     In order to help deliver balloon catheters and stent devices, special guiding catheters or sheaths are often used. These guiding catheters or sheaths are placed upstream from the targeted lesion or stenotic area. A guide wire may be advanced past the stenotic area, allowing the subsequent balloon catheters and stents to be advanced through the guiding catheter or sheath to the target area of the blood vessel.  
         [0005]     During a balloon angioplasty procedure and stent placement at the stenotic lesion, there may exist the risk of dislodging fragments of plaque, thrombus and/or other material. These fragments may become dislodged from the stenotic lesion when the balloon segment is inflated or during other parts of the procedure. If the lesion involves arterial circulation, then the dislodged particles could flow into smaller vessels in the brain, other organs, or extremities, thus resulting in disastrous complications. Likewise, if the lesions involve the venous circulation, then the dislodged fragments could flow into the heart and lungs, possibly resulting in the demise of the patient.  
         [0006]     Embolic protection devices are commonly used to provide protection from such dislodged fragments of plaque and thrombus. These protection devices often consist of a small umbrella-like filter or lasso-shaped device attached to the end of a guide wire. The filter is encompassed in a delivery sheath which is advanced past the lesion into a vessel segment upstream or distal to the lesion. The delivery sheath is then pulled back exposing the filter and allowing it to expand. The sheath is then removed. While expanded, the filter can capture dislodged particles while still allowing blood to freely flow past it. The filter will usually stay expanded during all major parts of the procedure. Predilatation, which is conventionally the first step of the procedure, provides an important stent by dilating the lesion usually with a small balloon catheter (2-4 mm in diameter).  
         [0007]     After the predilatation, a self-expandable stent is deployed and post dilated with a separate and larger balloon catheter. Embolic material created during predilatation and stent placement will be captured by the filter. However, if the debris is of a large volume, it can occlude flow through the filter. This can be a dangerous situation when the filter is recaptured, the debris could become dislodged and flow distally. When the procedure is completed, a separate retrieval catheter is often required to advance through the stented artery and used to collapse and retrieve the embolic protection device.  
         [0008]     The separate step of inserting a separate retrieval catheter is a major disadvantage of the current system of filter recovery. In carotid stent placement, longer procedure time and more steps are directly related to increased chance of a major complication occurring. Another disadvantage of the current system is that it is frequently difficult to advance the filter and the sheath together past tight and tortuous angles of some blood vessels.  
         [0009]     A need exists for a catheter capable of providing recovery of the deployed embolic filter while also providing a means to aspirate debris proximal to the filter and stenotic lesion of a blood vessel. A need also exists for a way of clearing a blocked embolic filter without requiring installation of a separate aspiration catheter.  
         [0010]     The present invention has been developed in view of the foregoing, and to address other deficiencies in the prior art.  
       SUMMARY OF THE INVENTION  
       [0011]     The invention relates to an apparatus and method for providing recovery of distal embolic protection devices while at the same time providing a means of aspirating thromboembolic debris.  
         [0012]     An aspect of the invention is to provide a vascular catheter comprising a shaft including an expanded distal tip structured and arranged to receive at least a portion of an embolic filter and a plurality of aspiration holes positioned along the shaft adjacent the expanded distal tip structured and arranged to allow aspiration of embolic material adjacent the distal tip within a blood vessel.  
         [0013]     Another aspect of the present invention is to provide a vascular catheter comprising a shaft including an expanded distal tip structured and arranged to receive at least a portion of an embolic filter, and means for aspirating embolic material through a side of the expanded distal tip.  
         [0014]     A further aspect of the present invention is to provide a vascular catheter having a distal end and a proximal end comprising a shaft including an expanded distal tip structured and arranged to receive at least a portion of an embolic filter, a guide sheath coaxially located inside of the shaft, a guide wire coaxially positioned within the guide sheath, and an embolic filter attached to the guide wire at a distal end, wherein the shaft and guide sheath are slidably related and the guide wire and guide sheath are slidably related.  
         [0015]     Another aspect of the present invention is to provide a vascular catheter having a distal end and a proximal end comprising a shaft including an expanded distal tip structured and arranged to receive at least a portion of an embolic filter, a guide wire coaxially positioned within the shaft, means for guiding the shaft along the guide wire, and an embolic filter attached to the guide wire at a distal end, wherein the shaft the guide wire are slidably related.  
         [0016]     A further aspect of the present invention is to provide s method of retrieving an embolic filter and aspirating embolic material from a blood vessel comprising retracting the embolic filter into an expanded distal tip of a retrieval catheter positioned in the blood vessel, and aspirating embolic material from the blood vessel through aspiration holes provided adjacent the expanded distal tip of the retrieval catheter.  
         [0017]     Another aspect of the present invention is to provide a method of using a vascular catheter having an outer retrieval catheter with an expanded distal tip and a guide sheath coaxially located in the retrieval catheter comprising the steps of advancing the vascular catheter along a guide wire coaxially located within the guide sheath, the guide wire having a distally located embolic filter, and coaxially located within the guide sheath to a point where the expanded distal tip is past a stenotic lesion in a blood vessel, and retracting the embolic filter into the expanded distal tip of the retrieval catheter.  
         [0018]     These and other aspects of the present invention will be more apparent from the following description. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIG. 1  is a partially schematic longitudinal anatomical view of a catheter apparatus in accordance with an embodiment of the present invention in a representation of a human carotid artery.  
         [0020]      FIGS. 2   a  and  2   b  are longitudinal side views of the apparatus of  FIG. 1 , including distal and proximal segments.  
         [0021]      FIGS. 3   a  and  3   b  are longitudinal cross sectional views of the distal and proximal segments.  
         [0022]      FIG. 4   a  is a longitudinal cross sectional view of an embodiment of the invention illustrating a distal segment with the guide sheath shortened and incorporated into the retrieval catheter.  FIG. 4   b  is a longitudinal cross sectional view of another embodiment of the invention illustrating a distal segment with the guide sheath attached to the retrieval catheter.  
         [0023]      FIGS. 5   a  and  5   b  are longitudinal cross sectional views of the distal and proximal segments with the guide sheath removed.  
         [0024]      FIGS. 6   a  and  6   b  are longitudinal side views of the apparatus of  FIG. 1 , including distal and proximal segments with the “Y-adaptor” removed and the guide sheath attached directly to the proximal hub.  
         [0025]      FIGS. 7   a  and  7   b  are longitudinal side views of a variation of the apparatus of  FIG. 1 , including distal and proximal segments with the filter guide wire exiting a sidehole.  
         [0026]      FIGS. 8   a  and  8   b  are longitudinal cross sectional views of the distal and proximal segments of the apparatus of  FIG. 6 .  
         [0027]      FIGS. 9   a  and  9   b  are longitudinal side views of a variation of another embodiment of the present invention including distal and proximal segments with the filter guide wire exiting a sidehole with a separate attached tube for aspiration.  
         [0028]      FIGS. 10   a  and  10   b  are longitudinal cross sectional view of the distal and proximal segments of the apparatus of  FIG. 8 .  
         [0029]      FIGS. 11   a  and  11   b  are longitudinal side views of an embodiment of the present invention including distal and proximal segments with the filter guide wire exiting a sidehole and the aspiration tube surrounding the main tube.  
         [0030]      FIGS. 12   a  and  12   b  are longitudinal cross sectional views of the distal and proximal segments of the apparatus of  FIG. 10 . 
     
    
     DETAILED DESCRIPTION  
       [0031]     Referring now to  FIG. 1 , in one embodiment of the invention the device is illustrated in the human internal carotid artery  2 . A guide wire  5  and embolic filter  6  are inserted into the carotid artery  4  where the embolic filter  6  is deployed at a position downstream from a lesion in the blood vessel  10 . The arrows in  FIG. 1  indicate the direction of blood flow. Balloon angioplasty and stent procedures may be performed once the embolic filter  6  is in place. A retrieval catheter  1 , which may be a shaft with an expanded distal tip  9 , is shown exiting a guide catheter  3  which is located in the common carotid artery  4 . The retrieval catheter  1  is coaxially located around a guide sheath  8 , which may be a flexible shaft coaxially located around the guide wire  5 . After a carotid artery stent  7  has been deployed within the carotid artery  2 ,  4  and the stent has been post-dilated, the retrieval catheter  1  is advanced coaxially past the stent  7  with the use of the guide sheath  8 . The guide sheath  8  helps to keep the expanded distal tip  9  of the retrieval catheter  1  off the edges of the stent  7 . Once past the stent and in the region just proximal to the filter, the guide sheath  8  is removed. Pieces of embolic debris  11  originating from the vessel may be aspirated through aspiration holes  12  and main lumen  15  located on the expanded distal tip  9  of the retrieval catheter  1 . Aspiration may be accomplished through a syringe system at the proximal end. After aspiration, the embolic filter  6  may be retracted into the expanded distal tip of the retrieval catheter. Retracting as used herein can mean pulling the filter towards the expanded distal tip  9  or advancing the retrieval catheter  1  and expanded distal tip  9  along the guide wire  5  towards the embolic filter  6  to capture the embolic filter  6 . Once captured, the retrieval catheter  1  and encapsulated embolic filter  6  may be removed from the body.  
         [0032]     In one embodiment the guide sheath  8  may be axially fixed in relation to the retrieval catheter. In this embodiment, the guide sheath  8  is filleted or slit open as the embolic filter  6  retracted into the expanded distal tip  9 .  
         [0033]      FIG. 2   a  shows a distal portion of the of the embodiment shown in  FIG. 1  including the retrieval catheter  1  having a transition segment  16  and distal trumpeted segment  9 . The transition segment  16  is the portion of the retrieval catheter wherein the diameter of the retrieval catheter  1  transitions to a greater diameter in the expanded distal tip  9 . Proximal and distal radiopaque markers  13 ,  14  located on the expanded distal tip allow  9  the retrieval catheter  1  to be easily located. Aspiration holes  12  within the expanded distal tip  9  are used to aspirate embolic debris  11 . Coaxially located between the guide wire  5  and the retrieval catheter  1  is the guide sheath  8 . The interior face of the retrieval catheter is a main lumen  15 . The main lumen  15  serves to aspirate embolic debris received from the aspiration holes  12  and any debris  11  received through a distal opening.  
         [0034]     Referring now to  FIG. 2   b,  the guide sheath  8  enters the device through the main port  20  which forms one leg of a Y-adapter  19 . The other leg of the Y-adapter is the aspiration port  21 . A luer end  18 , or other suitable threaded or compression fitting, may connect the Y-adapter to a proximal hub  17 . The distal end of the proximal hub  17  connects to the retrieval catheter  1 .  
         [0035]      FIG. 3   a  shows a cross sectional view of a distal end of the retrieval catheter  1  shown in  FIG. 1 . The guide sheath  8  has a lumen  22  in which the filter guide wire  5  (not shown in this figure) courses coaxially. In this embodiment a distal radiopaque marker  23  is positioned at a distal end of guide sheath  8 . Radiopaque markers  13 ,  14  are also shown at the proximal and distal ends of the expanded distal tip  9 . Aspiration holes  12  are shown as seen from the interior of the expanded distal tip  9 .  
         [0036]     Referring now to  FIG. 3   b  a cross section of the proximal end of the device of  FIG. 1  is shown. Retrieval catheter  1  connects to proximal hub  17  which is then connected to Y-adapter  19  through the use of luer end  18 . The guide sheath  8  and guide wire  5  (not shown) run through the retrieval catheter  1 , through the proximal hub  17  and exit through the main port  20  which may also have luer end  23 . Guide sheath  8  terminates at proximal end  24 . The interior of aspiration port  21  forms aspiration lumen  25 . Aspiration port  21  may also have luer end  26 .  
         [0037]     The embodiments shown in  FIGS. 3   a  and  3   b  are typical of what a cross section of the device may look like as the retrieval catheter  1  is moved into a position past a stent  7  and close to embolic filter  6 .  
         [0038]      FIGS. 4   a  and  4   b  show two other embodiments of the invention. In the embodiment shown in  FIG. 4   a  the guide sheath  8  is shortened and incorporated into the retrieval catheter  1 . The guide sheath  8  continues to keep the retrieval catheter in proper alignment along the guide wire  5  (not shown) but now is fixed in relation to the retrieval catheter  1 . In this embodiment, debris is aspirated through the lumen of the guide sheath  8 . In the embodiment shown in  FIG. 4   b,  the guide sheath  8  and the retrieval catheter  45  are attached together through attachment  45 . As described above the guide sheath  8  keeps the retrieval catheter  1  centered on the guide wire  5  (not shown). The attachment  8  keeps the retrieval catheter  1  and guide sheath  8  axially fixed in relation to each other. The attachment  45  has perforations or spokes so that debris may still be aspirated between the guide sheath and retrieval catheter  1 . The proximal end of the embodiment described in  FIG. 4   a  or  FIG. 4   b  may have a proximal hub  17  and Y-adapter  19  as described above or may include another proximal end as described herein.  
         [0039]      FIGS. 5   a  and  5   b  show the retrieval catheter  1  without guide sheath  8 . This configuration is what the device may look like once expanded distal tip  9  is in position proximal to embolic filter  6 . With guide sheath  8  removed more space is available in main lumen  15 . This facilitates aspiration through aspiration port  25 , main lumen  15  and aspiration holes  12 . Guide wire  5  is not shown but would be present in  FIGS. 5   a  and  5   b.  Connected at the distal end to an embolic filter  6  and exiting main port  20  at the proximal end.  
         [0040]      FIGS. 6   a  and  6   b  show another embodiment of the present invention in which the Y-adapter is removed. Once expanded distal tip  9  is at a position past the stent and near the embolic filter  6 , the guide sheath  8  may be removed through luer end  26 . Once the guide sheath  8  is removed an aspiration port (not shown) for removal of embolic debris can then be connected to luer end  26 .  
         [0041]      FIGS. 7 and 8  illustrate another embodiment of the present invention. A side port  27  is provided for access of the guide wire  5  through the retrieval catheter  1 . A secondary lumen  28  for the guide wire  5  is shown in  FIG. 8 . The secondary lumen  28  is located within the main lumen  15 . The main lumen  15  travels from the expanded distal tip  9  past the radiopaque markers  13 ,  14  and is connected to the luer end  18  through the proximal hub  17 . Guide wire  5  accesses the secondary lumen  28  through a side port  27 . The guide wire  5  enters the side port  27  at the proximal end of a secondary lumen  28 . The guide wire  5  exits main lumen  15  of the trumpeted distal end  9  and is attached to an embolic filter  6  (not shown).  
         [0042]      FIGS. 9 and 10  show another embodiment of the present invention wherein a separate distal aspiration tip  29 , aspiration lumen  30 , radiopaque marker  31  and aspiration holes  32  are provided. In this embodiment the secondary lumen  28  and side port  27  are connected but external to the aspiration lumen  30 . The aspiration lumen  30  communicates with a proximal hub  34  and luer end  35  at the proximal end. At the distal end, aspiration lumen  30  may include a expanded distal tip  9  and radiopaque markers  13 ,  14 . The guide wire  5  enters a side port  27  at the proximal end of a secondary lumen  28 . The guide wire  5  exits distal end opening  36  of the trumpeted distal end  9 . The guide wire  5  is attached to an embolic filter  6  (not shown).  
         [0043]      FIGS. 11 and 12  illustrate another embodiment of the present invention including a distal opening  36  of the expanded distal tip  9  of the retrieval catheter  1 . In this embodiment the aspiration lumen  43  encircles the secondary lumen  28  which carries the guide wire  5 . Guide wire  5  enters the proximal end at a side port  27 . The guide wire  5  exits distal end opening  36  of the expanded distal tip  9 . The guide wire  5  is attached to an embolic filter  6  (not shown). The expanded distal tip  9  has a tapered section  37 . Aspiration ports  38  with radiopaque markers  39  and aspiration holes  40  are located at a point proximal to the tapered section. Aspiration ports  38  and aspiration holes  40  are in communication with an aspiration lumen  43  at the distal end. The aspiration lumen  43  communicates with the proximal hub  34  and luer  35  at the proximal end.  
         [0044]     Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention.