Abstract:
A stent retrieval device for insertion in an artery and capable of being guided along a radiopaque wire is described. The stent retrieval device includes a plurality of flexible individual fingers housed in a flexible tube with the fingers normally biased toward the interior surface of the tube so that when they are pushed out of the tube they will expand the artery and then grasp the stent to be removed.

Description:
BACKGROUND OF THE INVENTION 
     Often times following balloon angioplasty, it is necessary to insert a coronary stent into the artery to keep the artery open. On occasion it is necessary to remove the stent from the artery. There are a number of devices that have been proposed for this purpose. One is shown in U.S. Pat. No. 5,098,440 Hillstead which is a loop device for engaging the stent and removing it. Another is U.S. Pat. No. 5,464,408 Duc which utilizes two flexible tubes with a number of gripping members which are part of the inner tube which are directed to engage the stent and pull it into the outer tube. U.S. Pat. No. 4,990,151 Wallsten shows a stent removal device where the portion which engages the stent is straight and would not expand the artery to permit the stent to be drawn back more easily. 
     In balloon angioplasty, a small radiopaque guidewire is steered through a coronary guiding catheter and down a coronary artery past the area of blockage and over the wire. The physician then passes a thin flexible tube with a balloon at the end of it into the blocked artery. By inflating the balloon, the plaque causing the blockage is pressed back against the artery wall. Doing this, of course, opens the artery and increases the blood flow through the artery to the heart muscle. When the coronary stent is introduced into the blood vessel, it is collapsed down upon the balloon catheter until it reaches the narrow area of the artery. Sometimes, however, the stent may slip back off the balloon or become dislodged in the placement process and must be retrieved. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention involves a stent retrieval device which may be guided along the radiopaque guidewire to the location where the stent is to be removed at which time the fingers of the device are pushed out of the tube in which they have been carried. They are naturally biased outward so that they will expand the artery and go over the stent and then grip it as the fingers are drawn back thus keeping the artery expanded and enabling the stent to be readily withdrawn from its location in the artery. 
     It is therefore an object of this invention to provide a stent removal device which may be inserted into an artery and grip a stent by enveloping it between the stent and the interior artery wall, and thus grasp it and remove it. 
     It is a further object of this invention to provide such a stent removal device that may be guided along the radiopaque guidewire. 
     This, together with other objects of the invention, will become apparent from the following detailed description of the invention and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view, partly in section, showing applicant&#39;s invention in use in grasping a stent inside of an artery. 
     FIG. 2 is a section of FIG. 1 in the plane  2 — 2 . 
     FIG. 3 is a side elevation of applicant&#39;s invention, partly in section, showing its movement through artery along the radiopaque guidewire. 
     FIG. 4 is a view of applicant&#39;s invention with the fingers expanded and commencing to expand the artery and grasp the stent. 
     FIG. 5 is a sectional view of a portion of applicant&#39;s invention showing the provision for guiding the radiopaque guidewire out of applicant&#39;s invention. 
     FIG. 6 is a section of FIG. 5 in the plane  6 — 6 . 
     FIG. 7 is a section of FIG. 5 in the plane  7 — 7 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, applicant&#39;s invention is shown generally at  10  and consists of a handle  11 , a spring loaded member  12  which is attached to a hollow rod  13  which is located inside of the major shaft  14  and which in turn is connected to flexible tube  15  surrounding the radiopaque guidewire  16  inside the flexible guiding catheter  17 . The end of the hollow rod  13  is connected to a base  17   a  supporting a plurality of fingers  18 — 18  which are spaced around the inner circumference of the tube  15 . The tube  14  is provided with a channel portion  14   a  to permit the rod  13  to be moved in our out of the artery and also to permit connecting shaft  19  to move accordingly. The fingers  18 — 18  are normally in a retracted position in flexible tube  15  as this flexible tube moves along the radiopaque guidewire  16  through the artery  20 . A radiopaque marker  22  is provided at the end of the flexible tube  15  so as to enable the physician to locate the end of flexible tube  15  prior to opening the fingers  18 — 18 . The guidewire  16  is led out of the flexible tube  15  by means of the shaft  19  which may be provided with a conventional lure lock  21  which is used for flushing tube  15  prior to insertion. All of this activity, of course, is being observed by means of a fluoroscope on the part of the operator of the device and when the flexible tube  15  nears the stent  23 , the fingers  18 — 18  are pushed forward out of the flexible tube  15  by means of the spring loaded member  12 , normally biased outward by spring  24 , and the fingers  18 — 18  will expand the interior of the artery  20  and encompass the stent  23 . The ends of the fingers  18 — 18  are preferably bent inwardly as shown at  25 — 25  to more readily grasp the stent  23 . 
     As shown at FIG. 2, it will be seen that the rod  13  is U-shaped in cross section so that the radiopaque guidewire  16  will fit inside of it. 
     Referring now to FIG. 3, the fingers  18 — 18  are just now beginning to emerge from the flexible tube  15  by applying slight pressure on the spring loaded member  12  against spring  24 . 
     Referring now to FIG. 4, further pressure has been applied to spring loaded member  12  and the fingers  18 — 18  have further expanded since they are normally biased outwardly and are beginning to expand and push out the interior of the artery  20  so as to grasp stent  23 . When the stent  23  has been grasped as shown in FIG. 1, then the entire unit including the flexible guiding catheter  17  and the flexible tube  15  may be removed from the artery along with the stent  23  and eventually, of course, the radiopaque guidewire  16  is also removed. 
     FIG. 5 is a sectional view of applicant&#39;s invention showing the radiopaque guidewire  16  traveling in the rod  13  which as shown in FIG. 2 is U-shaped in cross section to accommodate the radiopaque guidewire  16  where it is positioned in the rod  13 . 
     FIG. 6 is a sectional view showing where rod  13  joins round base  17   a  to which the fingers  18 — 18  are attached. 
     FIG. 7 is a section along the plane  7 — 7  showing the radiopaque wire  16  entering the U-shaped portion of rod  13 . 
     In operation with the radiopaque guidewire  16  in place in the artery  20 , the radiopaque guidewire  16  is threaded through the flexible tube  15  and the hollow rod  13  and out the slot  19 . The flexible tube  15  is then inserted through the flexible guiding catheter  17  until the area of the stent  23  is located. During this time the fingers  18 — 18  are retracted into the flexible tube  15 . When the flexible tube  15  approaches the stent  23 , the spring loaded member  12  is pressed in and the fingers  18 — 18  which are biased outwardly are pushed out and expand as shown in FIG.  4  and commence to enlarge the interior walls of the artery  20  until they embrace the stent  23  and then the pressure on the spring loaded member  12  is partially relieved permitting the fingers  16  to be drawn slightly back toward the flexible tube  15 . Then the entire stent  23  with fingers  18 — 18  grasping the stent  23 , and the flexible tube  15  and the flexible guiding catheter  17  are withdrawn along the radiopaque guidewire  16  to the exterior of the artery  20 . 
     In using this device for stent removal, great reliability is achieved. 
     While this device is shown for use in the coronary arteries, it can also be used in the periphery vessels in the arms and legs and also in the operating room during laparoscopy. 
     While this invention has been shown and described with respect to a detailed embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the scope of the claims of the invention.