Abstract:
A stent delivery assembly includes a catheter for carrying an intravascular stent for use in a body lumen. The catheter assembly includes a rapid exchange feature in which a proximal port is spaced a relatively short distance form the distal end of the catheter and a relatively long distance from the proximal end of the catheter. A stent is mounted on the expandable member or balloon portion of the catheter.

Description:
RELATED APPLICATION 
     This application is a CON of Ser. No. 09/136,982 filed Aug. 20, 1998 which is a divisional of U.S. Ser. No. 09/119,344 filed Jul. 20, 1998, now U.S. Pat. No. 6,113,607, which is a divisional of U.S. Ser. No. 08/630,528 filed Apr. 10, 1996, now U.S. Pat. No. 5,782,855, which is a divisional of U.S. Ser. No. 08/085,959 filed Jul. 6, 1993, now U.S. Pat. No. 5,507,768, which is a continuation-in-part application of U.S. Ser. No. 07/647,464 filed Jan. 28, 1991 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to devices for the treatment of heart disease and particularly to endo-arterial prosthesis, which are commonly called stents. Several interventional treatment modalities are presently used for heart disease including balloon and laser angioplasty, atherectomy and by-pass surgery. In typical balloon angioplasty procedures, a guiding catheter having a preformed distal tip is percutaneously introduced through the femoral artery into the cardiovascular system of a patient in a conventional Seldinger technique and advanced within the cardiovascular system until the distal tip of the guiding catheter is seated in the ostium of a desired coronary artery. A guidewire is positioned within an inner lumen of a dilatation catheter and then both are advanced through the guiding catheter to the distal end thereof. The guidewire is first advanced out of the distal end of the guiding catheter into the patient&#39;s coronary vasculature until the distal end of the guidewire crosses a lesion to be dilated, then the dilatation catheter having an inflatable balloon on the distal portion thereof is advanced into the patient&#39;s coronary anatomy over the previously introduced guidewire until the balloon of the dilatation catheter is properly positioned across the lesion. Once in position across the lesion, the balloon which is made of relatively inelastic materials, is inflated to a predetermined size with radiopaque liquid at relatively high pressure (e.g., greater than 4 atmospheres) to compress the arteriosclerotic plaque of the lesion against the inside of the artery wall and to otherwise expand the inner lumen of the artery. The balloon is then deflated so that blood flow can be resumed through the dilated artery and the dilatation catheter can be removed therefrom. Further details of dilatation catheters, guidewires, and devices associated therewith for angioplasty procedures can be found in U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185 (Lindquist); U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,538,622 (Samson, et al.); U.S. Pat. No. 4,554,929 (Samson, et al.); U.S. Pat. No. 4,616,652 (Simpson); U.S. Pat. No. 4,638,805 (Powell); and U.S. Pat. No. 4,748,982 (Horzewski, et al.) which are hereby incorporated herein in their entirety by reference thereto. 
     A major problem which can occur during balloon angioplasty procedures is the formation of intimal flaps which can collapse and occlude the artery when the balloon is deflated at the end of the angioplasty procedure. Another major problem characteristic of balloon angioplasty procedures is the large number of patients which are subject to restenosis in the treated artery. In the case of restenosis, the treated artery may again be subjected to balloon angioplasty or to other treatments such as by-pass surgery, if additional balloon angioplasty procedures are not warranted. However, in the event of a partial or total occlusion of a coronary artery by the collapse of a dissected arterial lining after the balloon is deflated, the patient is put in an extremely dangerous situation requiring immediate medical attention, particularly in the coronary arteries. 
     A major focus of recent development work in the treatment of heart disease has been directed to endoprosthetic devices called stents. Stents are generally cylindrically shaped intravascular devices which are placed within a damaged artery to hold it open. The device can be used to prevent restenosis and to maintain the patency of blood vessel immediately after intravascular treatments. In some circumstances, they can also be used as the primary treatment device where they are expanded to dilate a stenosis and then left in place. 
     However, the rapid and effective delivery of a stent to the desire location within the patient&#39;s vasculature has been found to be difficult, particularly in those situations in which an intimal flap has occluded an artery. Attempts to advance a stent into regions of coronary arteries occluded by dissected arterial linings have not been very successful. 
     The two basic methods and systems have been developed for delivering stents to desired locations within body lumens. One method and system involves compressing or otherwise reducing the diameter of an expandable stent, disposing the compressed stent within a lumen provided in the distal end of a tubular catheter, advancing the catheter through the patient&#39;s vasculature until the distal end of the catheter is immediately adjacent to the desired vascular location and then pushing the stent out the distal end of the catheter into the desired location. Once out of the catheter, the compressed stent expands or is expanded to thereby hold open the artery or other body lumen into which it is placed. 
     Another method and system involves disposing a compressed or otherwise small diameter stent about an expandable member such as a balloon on the distal end of a catheter, advancing the catheter through the patient&#39;s vascular system until the stent is in the desired location within a blood vessel and then expanding the expandable member on the catheter to expand the stent within the blood vessel. The expanded expandable member is then contracted and the catheter withdrawn, leaving the expanded stent within the blood vessel, holding open the passageway thereof. 
     The following references illustrate various types of stents and stent delivery systems. The list is meant to be exemplary, not exhaustive on the subject. 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 U.S. 3,868,956 
                 U.S. 4,733,665 
                 U.S. 4,856,516 
               
               
                   
                 U.S. 4,503,569 
                 U.S. 4,760,849 
                 U.S. 4,878,906 
               
               
                   
                 U.S. 4,512,338 
                 U.S. 4,762,128 
                 U.S. 4,886,062 
               
               
                   
                 U.S. 4,553,545 
                 U.S. 4,768,507 
                 U.S. 4,907,336 
               
               
                   
                 U.S. 4,560,374 
                 U.S. 4,795,458 
                 U.S. 4,913,141 
               
               
                   
                 U.S. 4,655,771 
                 U.S. 4,800,882 
                 U.S. 4,923,464 
               
               
                   
                 U.S. 4,665,918 
                 U.S. 4,830,003 
                 U.S. 4,950,227 
               
               
                   
                   
               
             
          
         
       
     
     What has been needed and heretofore unavailable is a stent delivery system which can be quickly and easily used in a wide variety of situations and particularly in emergency situations where a dissected arterial lining has collapsed and has occluded the flow of blood to a vital organ. The present invention satisfies this need. 
     SUMMARY OF THE INVENTION 
     This invention is directed to an improved stent delivery system which can quickly and easily position a stent into an occluded region of a blood vessel. 
     The stent delivery system of the invention includes an elongated sheath having an inner lumen extending therein, a first port in its distal end which is adapted to receive a guidewire and a second port spaced proximally from the distal end of the delivery sheath which is also adapted to receive a guidewire, both of the ports being in fluid communication with the inner lumen of the sheath. The delivery system also includes an intravascular catheter slidably disposed within the inner lumen of the delivery sheath, the catheter having an expandable member on the distal extremity thereof, such as an inflatable balloon, which is adapted to receive an expandable stent on the exterior thereof The catheter has a first port in its distal end adapted to receive a guidewire and a second port spaced proximally from the distal end of the catheter adapted to receive a guidewire, with both of these ports being in communication with an inner lumen extending within the interior of the catheter. The second guidewire receiving port should be spaced proximally from the expandable member on the distal extremity of the catheter. Means may be provided to adjust the relative axial positions of the catheter and sheath to expose the expandable stent on the expandable member of the catheter so that the stent can be expanded against the blood vessel wall by expanding the expandable member. 
     Preferably, both the delivery sheath and the intravascular catheter have slits in the walls, thereof which extend distally from their proximal ports to facilitate the removal of these devices from the guidewire upon the withdrawal of the delivery system from the patient&#39;s vascular system after the delivery of a stent. 
     In a typical situation, the guidewire used to deliver a dilatation catheter through the patient&#39;s vascular system to a stenotic region therein is left disposed within the patient after the dilatation catheter has been removed therefrom. To maintain access to the stenotic region, the distal end of the guidewire should be left crossing the stenotic region where the stent is to be placed. The proximal end of the guidewire, which extends out of the patient, is first inserted through an elastic cone by threading the guidewire into the smaller and out the larger of the two apertures which comprise the cone, then the guidewire is inserted through the port in the distal end of the intravascular catheter which has a stent mounted on the expandable member. The intravascular catheter is disposed within the inner lumen of the delivery sheath with the distal end of the catheter extending out the port in the distal end of the delivery sheath to facilitate the insertion of the proximal end of the guidewire. The relative axial position between the delivery sheath and intravascular catheter is adjusted so that the expandable member on the distal extremity of the intravascular catheter with the expandable stent mounted thereon is pulled back into the inner lumen of the delivery sheath. The distal end of the delivery sheath is then tucked within the large aperture of the elastic cone. Tucking the delivery sheath within the elastic cone aids the advancement of the stent delivery system through the patient&#39;s vascular system by providing the system with a profile suited for making turns through tortuous vessels. The delivery sheath and the catheter therein are then advanced through the patient&#39;s vascular system, preferably over a guidewire which extends from outside the patient to the ostium of the desired coronary artery, over a guidewire which extends from outside the patient to the ostium of the desired coronary artery, until the stent mounted on the expandable member of the intravascular catheter is positioned within the stenotic region of the patient&#39;s blood vessel. 
     The relative axial positions of the delivery sheath and the intravascular catheter having the stent thereon is adjusted to urge the distal end of the vascular catheter out of the distal end of the sheath to expose the expandable stent. Either the catheter can be advanced distally with respect to the sheath or the sheath can be withdrawn proximally with respect to the catheter or both movements can be employed. Once the stent is completely out of the delivery sheath, the expandable member on the intravascular catheter can be expanded to expand the stent against stenotic mass within the blood vessel. After expanding the stent, the expandable member on the vascular catheter is contracted so that the catheter can be removed from the patient&#39;s blood vessel, leaving the expanded stent in its desired position therein. 
     The delivery sheath and the intravascular catheter may be withdrawn together or the sheath may be withdrawn first followed by withdrawal of the catheter. They are removed over the guide wire until the proximal guide wire port on the sheath and/or the catheter exits the proximal end of the guiding catheter, the sheath and the catheter can be peeled away from the guidewire with the guidewire sliding through the slits which extend distally from the proximal ports thereof. The exposed section of the guidewire is secured, e.g., manually held, in place so that the sheath and the intravascular catheter can be pulled off the proximal end of the guidewire. 
     The delivery system of the invention can effectively deliver a stent to a desired location within a patient&#39;s blood vessel, it can allow the stent to be secured within the desired location, and it can be easily and quickly removed. These and other advantages of the invention will become more apparent from the following detailed description of the invention, when taken in conjunction with the accompanying exemplary drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial longitudinal cross-sectional view of a stent delivery system which embodies features of the invention. 
     FIG. 2 is a top view of the delivery sheath shown in FIG.  1 . 
     FIG. 3 is a transverse cross-sectional view taken along the lines  3 - 3  shown in FIG.  1 . 
     FIG. 4 is a transverse cross-sectional view taken along the lines  4 - 4  shown in FIG.  1 . 
     FIG. 5 illustrates a stent mounted on the outer surface of a balloon of the intravascular catheter shown in FIG.  1 . 
     FIG. 6 illustrates the advancement of the stent delivery system shown in FIG. 5 into an artery which has been damaged by an intravascular procedure such as an angioplasty and 
     FIG. 7 illustrates the inflation of the balloon on the intravascular catheter shown in FIG. 1 which expands the stent mounted on the exterior thereof and 
     FIG. 8 illustrates the expanded stent disposed within a damaged arterial section maintaining the patency thereof. 
     FIG. 9 is a partial cross-sectional view of the manipulator shown in FIG.  1 . 
     FIG. 10 is a perspective view of an alternative manipulator mounted on the proximal end of the delivery system shown in FIG.  1 . 
     FIG. 11 is a plan view of the manipulator shown in FIG.  10 . 
     FIG. 12 is an elevational view, partially in section, of the manipulator shown in FIG.  10 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1-4 illustrate a stent delivery system which embodies features of the invention. Generally, the delivery system includes a delivery sheath  10  which has an inner lumen  11  and an intravascular catheter  12  disposed within the outer lumen  11 . The intravascular catheter has an elongated catheter body  13  and a balloon  14  on the distal portion of the catheter body. A manipulating device  15  is provided on the distal end of the delivery system which is employed to effect relative axial or longitudinal movement between the delivery sheath  10  and the intravascular catheter  12 . An expandable stent  16 , which is to be delivered within a patient&#39;s body lumen, is mounted on the exterior of the balloon  14 . 
     The delivery sheath  10  has a distal port  17  in its distal end which is in fluid communication with the outer lumen  11  and a proximal port  18  disposed proximally to the distal port. The distal portion of delivery sheath  10  tapers down in a spherical-like manner so that the cross-sectional area is somewhat less in the distal region than the cross-sectional area of the rest of the delivery sheath. A slit  19  extends from the proximal port  18  to the distal port  17 . In one embodiment, a plurality of slits  59  in the wall of sheath  10  extend a short distance from the distal port  17 . As contemplated, the slits  59  would facilitate in the relative axial position adjustment of the sheath  10  and intravascular catheter  12 . 
     The intravascular catheter  12  has a distal port  20  and a proximal port  21  which are in fluid communication with a first inner lumen  22  extending within the distal portion of the catheter  12  and being adapted to slidably receive a guidewire therein. A slit  23  extends from the proximal port  21  to a location  24  proximal to the proximal end of balloon  14 . The proximal end of the guidewire receiving first inner lumen  22  is provided with a ramp  25  to guide the proximal end of guidewire  26  out the proximal port  21  of intravascular catheter  12  when the catheter is mounted onto the guidewire, as will be discussed hereinafter. A second, much longer inner lumen  27  is provided within the catheter body  13  to direct inflation fluid from the proximal end of the catheter body to the interior of the balloon  14 . 
     Proximal to the proximal port  21  in the catheter body  13  is a stiffening member  28  which is disposed in third inner lumen  29  provided within the catheter body  13 . As shown in the drawings, the third inner lumen  29  and the first inner lumen  22  may be the same lumen with a plug  30  separating the two lumens. The ramp  25  is on the distal side of the plug  30 . 
     As illustrated in FIGS. 1 and 9, the manipulator  15  on the proximal end of the delivery system has a housing  31  with an interior chamber  32 , a cap  33  rotatably mounted onto the distal end of the housing  31 , an elongated drive member  34  which has male threads on the exterior, thereof and which is at least partially disposed within the interior chamber  32  and a Luer lock  35  which is fixed within the proximal end of the housing  31 . The proximal end  36  of the sheath  10  is secured to the distal end  37  of the elongated drive member  34  which extends out of the distal end of the housing  31 . As shown in more detail in. FIG. 9, the proximal end  38  of the catheter body  13  passes through passageway  39  in the elongated drive member  34  and is fixed within the Luer lock  35  by suitable means such as adhesive. The cap  33  which is rotatably mounted onto the distal end of the housing  31  is provided with an inner threaded collar  40  adapted to threadably engage the threaded exterior of the elongated driving member  34 . Rotation of the cap  33  moves the driving member  34  axially to thereby effect relative axial movement between the sheath  10  and the intravascular catheter  12 . 
     In a typical situation, the stent delivery system of the invention is used after an intravascular procedure has damaged a patient&#39;s arterial lining to such an extent that the lining needs support to prevent it from collapsing into the arterial passageway and thereby preventing sufficient blood flow through the blood vessel. In these situations there will usually be a guidewire  26  (or other guiding member) in place extending across the damaged section of the artery such as shown in FIG.  6 . The proximal end of the guidewire  26 , which extends out of the patient during the entire procedure, is then inserted through the distal port  20  in the distal end of the catheter  12  and advanced proximally through the first inner lumen  22  until the proximal end of the guidewire impacts the ramp  25  and is thereby directed through the proximal port  21 . 
     The intravascular catheter  12  is preferably positioned within the inner lumen  11  of the delivery sheath  10  so that at least a significant portion of the proximal port  18  in the sheath is in alignment with the proximal port  21  of the intravascular catheter. In this manner, proximal advancement of the guidewire  26  through the inner lumen  22  will also direct the proximal end of the guidewire out the proximal port  18  in the delivery sheath  10 . The proximal end of the guidewire  26  may then be manually held to maintain the position of the guidewire within the patient&#39;s vasculature, while the stent delivery system is advanced over the guidewire and through the patient&#39;s vascular system. The advancement of the stent delivery system continues until the distal ends of the catheter and sheath extend adjacent to or across the damaged arterial site. Next, the manipulator  15  on the proximal end of the delivery system is actuated by rotating the cap  33  on the proximal end of the housing  31  to move the sheath  10  proximally with respect to the catheter  12  and thereby expose the stent  16  mounted on the balloon  14 . When the balloon and the stent mounted thereon are properly placed within the damaged artery, inflation fluid is directed under substantial pressure through the Luer lock  35  and the inflation lumen  27  in the catheter body  13  to the interior of the balloon  14 , expanding the balloon and simultaneously expanding the stent  16  against the blood vessel wall as shown in FIG.  7 . The delivery system, both the sheath  10  and the catheter  12 , may then be removed from the patient along with the guidewire  26 , leaving the expanded stent  16  within the damaged arterial section as shown in FIG. 8 to maintain the patency thereof. 
     The housing  31  of the manipulator  15  can be held in the palm of the physician&#39;s hand, with the thumb and index finger thereof used to rotate cap  33  and thereby cause the necessary relative motion between the sheath  10  and intravascular catheter  12  to expose the stent  16  mounted on the balloon  14 . The physician can operate an inflation device, such as described in U.S. Pat. No. 4,439,185, with his or her free hand to inject inflation fluid through Luer lock  35  into the interior of the balloon  14  to inflate the balloon and thereby expand the stent  16  while holding the delivery system in place with the other hand. Upon deflating the balloon  14 , the manipulator  15  can again be actuated by the physician rotating cap  33  with the fingers of the hand holding the manipulator  15 , to cause relative rotation between the intravascular catheter  12  and the sheath  10 , to pull the intravascular catheter  12  back into the distal end of the sheath  10  (or pushing the distal end of the sheath over the distal end of the intravascular catheter  12 , depending upon the perspective). The entire assembly, including the guidewire  26 , can then be removed from the patient. 
     The alternative manipulator  50  illustrated in FIGS. 10-12 generally includes a housing  51  with an interior chamber  52  and a slidable element  53  with a depending portion  54  which extends through a slot  55  in the wall of the housing and is secured to the proximal end of the sheath  10  which extends through an opening provided in the distal end of the housing. The catheter  12  extends out the proximal end of the sheath  10 , out an opening in the proximal end of the housing  51  and into a Luer lock  56  secured to the proximal end of the housing. The proximal end of the catheter  12  is secured within the Luer lock  56  to be in fluid communication with the inner inflation lumen  27  of the catheter so that inflation fluid can be injected through the Luer lock to the interior of the balloon  14  on the catheter to expand the balloon and the stent  16  mounted thereon. As is evident from FIG. 10, movement from element  53  on the exterior of the housing  51  will effect the relative axial movement between the delivery sheath  10  and the catheter  12  required to expose the stent  16  mounted on the balloon  14 . The slot  55  has narrowed portions near both ends thereof which have widths just slightly smaller than the depending element  54  so that the position of the slidable element  53  can be locked. The underside of the housing  51  may be provided with undulated surface  57  which is adapted to receive the fingers of an operator to facilitate the gripping thereof. 
     The dimensions of the intravascular catheter will generally follow the dimensions of intravascular catheters used in angioplasty procedures in the same arterial location. Typically, the length of a catheter for use in the coronary arteries is about 150 cm, the outer diameter of the catheter shaft is about 0.035 inch (0.89 mm), the length of the balloon is typically about 2 cm and the inflated diameter about 1 to about 8 mm. 
     The materials of construction may be selected from those used in conventional balloon angioplasty catheters, such as those described in the patents incorporated by reference. The delivery sheath will generally be slightly shorter than the intravascular catheter, e.g., by about the length of the manipulating device  15  or  50 , with an inner diameter large enough to accommodate the intravascular catheter and to allow the catheter free longitudinal movement therein. The sheath and the catheter shaft can be made of conventional polyethylene tubing. 
     While the present invention has been described herein in terms of delivering an expandable stent to a desired location within a patient&#39;s blood vessel, the delivery system can be employed to deliver stents to locations within other body lumens such as urethra or Fallopian tubes so that the stents can be expanded to maintain the patency of these body lumens. Various changes and improvements may also be made to the invention without departing from the scope thereof.