Patent Publication Number: US-2012046683-A1

Title: Devices and methods for temporarily opening a blood vessel

Description:
BACKGROUND OF THE INVENTION 
     The present invention is directed to devices and methods for temporarily opening a blood vessel. The present invention may be used to temporarily open a blood vessel in any part of the body such as in the cerebral vasculature. 
     The present invention is also directed to opening blood vessels and may be useful in dissolving or removing obstructions from blood vessels as well. Mechanical removal of obstructions can be problematic at times due to the forces necessary to release the obstruction from the vessel wall. This could be a result of the obstruction physiologically binding to the vessel wall, increased blood pressure at the face of the clot, vessel collapse during retrieval and most likely some combination of any or all of these scenarios. 
     SUMMARY OF THE INVENTION 
     The present invention provides a cage, which is used to temporarily open a vessel. In one application, the cage may be used to open a vessel at a location where an obstruction exists. The cage is positioned within the obstruction and expanded to enhance blood flow in the region. The cage has a relatively open structure, which permits blood to pass therethrough. As such, the natural dissolution of the obstruction can be accelerated or enhanced by providing enhanced blood flow through the region. 
     Another advantage of the present invention is that the enhanced blood flow through the obstruction may help to perfuse blood to the oxygen-starved tissue distal to the occlusion thereby minimizing or eliminating tissue necrosis and severity of the stroke. 
     After a period of time, the obstruction is assessed using an angiogram or other method of determining to what degree the obstruction has been dissolved. An obstruction-removing device may also be delivered through the lumen to engage a distal portion of the obstruction. The cage may also be used to remove the obstruction. The cage may remain expanded or may be partially collapsed when aiding in removal of the obstruction. The removal device and cage may be used together to remove the obstruction by simultaneously manipulating the cage and removal device. 
     In another aspect of the present invention, the cage may form a reinforcing portion of the shaft, which extends proximal to the cage and/or distal to the cage. Using the cage to reinforce the catheter shaft may help to reduce the overall profile of the catheter. 
     These and other aspects of the present invention will become apparent from the following description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a catheter in accordance with the present invention. 
         FIG. 2  shows the catheter positioned within an obstruction. 
         FIG. 3  shows a cage expanded within the obstruction. 
         FIG. 4  shows a portion of the obstruction, which has dissolved. 
         FIG. 5  shows a removal device used with the catheter. 
         FIG. 6  shows the cage deployed within the vessel. 
         FIG. 7  shows a snare used to re-engage the cage. 
         FIG. 8  shows the snare tightened around the shaft. 
         FIG. 9  shows another catheter advanced over the snare. 
         FIG. 10  shows another catheter having an expandable cage. 
         FIG. 11  shows the catheter expanded within an obstruction. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1-3 , a device  2  for temporarily opening a blood vessel is shown. The device  2  includes an expandable cage  4 . The cage  4  is naturally biased toward the expanded position of  FIG. 1  but can be collapsed into a delivery catheter  6  as shown in  FIG. 2 . The cage  4  may also be expanded with a balloon or the like rather than being self-expandable without departing from various aspects of the present invention. 
     The cage  4  may be formed in a manner similar to a stent. As such, the cage  4  may be formed from a single integrally formed piece of material such as a stainless steel or nitinol tube with material removed from the tubes to form openings  8  in the cage  4 . The cage  4  may also be formed in any other manner, which produces a relatively open structure for the reasons described below. The cage  4  has a relatively open structure so that the openings  8  in a proximal portion  12  of the cage  4  may permit blood or other fluids to pass therethrough. 
     The cage  4  is mounted over a shaft  14  having a lumen  16 . The shaft  14  extends beyond a distal end  18  of the cage  4  so that the lumen  16  may be used to access the vasculature distal to the cage  4  as described below. The lumen  16  may also have one or more holes  20  along the portion of the lumen  16  positioned beneath the cage  4  to deliver therapeutics. The hole(s)  20  may enhance blood flow in this area to help dissolve the obstruction as explained below. 
     The present invention may be useful in dissolving or removing obstructions from blood vessels. To this end, the cage  4  is advanced to a location where an obstruction is blocking blood flow in a vessel. The delivery catheter  6  is advanced through the obstruction as shown in  FIG. 2  and then withdrawn to expose the cage  4  as shown in  FIG. 3 . The delivery catheter  6  may be the catheter described in U.S. patent application Ser. No. 11,490,843, filed Jul. 21, 2006, which is incorporated herein by reference. The cage  4  will automatically expand within the vessel to partially open the vessel as shown in  FIG. 3 . The openings  8  in the proximal portion of the cage  4  may permit some blood to pass through the obstruction. As such, the natural dissolution of obstruction can be accelerated or enhanced by providing some blood flow across the obstruction as shown in  FIG. 4 . Another advantage of the present invention is that the enhanced blood flow through the obstruction may help to perfuse blood to the oxygen-starved tissue distal to the occlusion thereby minimizing or eliminating tissue necrosis and severity of the stroke. As described herein, the methods of temporarily opening a blood vessel include, of course, the concept of opening an obstruction, which lies within the blood vessel thereby opening the vessel as well. 
     The cage  4  may be maintained in the blood vessel for a period of time to achieve some of the benefits described above. After a period of time, which may be as little as a few minutes or as long as several days, an angiogram (or other visualization method such as CT, MRI or Ultrasound, etc.) can be performed to assess the status of the obstruction. If the clot has dissolved and flow has been restored, the cage can be collapsed using the delivery catheter  6  and then removed. If the clot has not fully dissolved in a satisfactory time period, the obstruction may be removed mechanically. 
     Referring to  FIG. 5 , an obstruction removal device  22  is shown which may be used to remove the obstruction. The device  22  is advanced through the lumen  16  until the device  2  extends from the distal end of the lumen  16 . The removal device  22  may then be manipulated to engage and ensnare the obstruction. For example, the device  22  may be twisted in one, both or neither direction and pulled proximally to engage and ensnare the obstruction. The obstruction removal device  22  may take any other suitable form without departing from numerous aspects of the present invention. 
     The cage  4  may also be used to help remove the obstruction. The cage  4  may be left partially (or even fully) expanded to help aid in removing the obstruction. The cage  4  may be manipulated independently of the removal device  22  or may be manipulated with the removal device  22 . For example, the cage  4  and removal device  22  may be moved proximally together to dislodge and remove the obstruction. 
     Referring to  FIG. 6 , the cage  4  may also be deployed within the blood vessel. The cage  4  may be released using any suitable connection such as an electrolytically severable connection  30  (see  FIG. 1 ) as is known in the art. The cage  4  is then left in the body to achieve some of the benefits described herein. The cage  4  may then be re-engaged and removed as now described. 
     A snare  32  is deployed through the delivery catheter  6  to re-engage the cage  4  as shown in  FIGS. 7-9 . The snare  32  is moved over a proximal portion of the catheter  14  and closed to hold the catheter  14 . The catheter  6  is then advanced while maintaining tension on the snare  32  to prevent the cage  4  from moving as the catheter  6  is advanced. As the catheter  6  is advanced, the cage  4  is collapsed into the catheter  6  for removal. Once the catheter  6  has become re-engaged with the cage  4 , the removal device  22  may also be used to help remove the obstruction if necessary. The cage  4  may be re-engaged in any other suitable manner other than a snare  32  such as a catheter or wire having a hook or a mechanical connector. 
     Referring to  FIGS. 10 and 11 , another catheter  40  is shown which has a cage  42  to temporarily open a blood vessel. The catheter  40  includes a shaft  44  that is reinforced by the cage  42 . The cage  42  may extend into and reinforce a proximal shaft portion  46  and/or a distal shaft portion  48  which extend from the proximal and distal ends of the cage  42 . The cage  42  is a braided structure but may also be a helical coil, or an integrally formed stent-like structure without departing from various aspects of the invention. The cage  42  will automatically expand when moved outside a delivery catheter  50  as shown in  FIG. 11 . Using the cage to reinforce the catheter shaft may help to reduce the overall profile of the catheter  40 . 
     The catheter  40  may be used in the same manner as the other catheters described herein and such use is expressly incorporated here. For example, the catheter  40  may include the electrolytically severable connection  30  so that the cage  42  and a portion of the shaft  44  may be released within the vessel. The catheter  40  may also be used to remove the obstruction as mentioned above together with or independent of the removal device  22  ( FIG. 5 ).