Abstract:
A multistage balloon catheter that uses a single lumen to inflate a balloon in stages is disclosed. A fluid port provides fluid communication from an inflation lumen in the balloon catheter to the inner volume of a distal balloon. The distal balloon expands as fluid in delivered to the inner volume of the distal balloon. Once inflated, the pressure continues to rise until a threshold pressure is exceeded. A pressure sensitive inflation valve provides fluid communication into an inner volume of a second balloon disposed at least partially proximal to the distal balloon. The pressure sensitive valve allows fluid communication into the second balloon once the threshold pressure is reached in the first balloon thereby inflating the second balloon.

Description:
RELATED APPLICATIONS 
       [0001]    The present patent document claims the benefit of the filing date under 35 U.S.C. §119(e) of Provisional U.S. Patent Application Ser. No. 61/784,522, filed Mar. 14, 2013, which is hereby incorporated by reference. 
     
    
     FIELD 
       [0002]    Embodiments of the present invention relate to methods and apparatuses for delivering an endoluminal prosthesis, such as a stent, and more particularly, to methods and apparatuses for delivering a stent into an ostium of a blood vessel or other body lumen. 
       BACKGROUND 
       [0003]    Stents are an established method of treatment for conditions such as stenosis, occlusions, and other lesions within a patient&#39;s vascular system or other body lumens. An unexpanded stent is typically delivered on a catheter and expanded in place to dilate the treatment site and provide support to the lumen walls. The stent may be self-expanding, in which the stent is biased to expand when a constraint, such as when a sheath is removed. Other stents may require the use of a balloon within the stent to expand the stent. 
         [0004]    Lesions and other conditions may occur at any location within a body lumen. In a location where a branch vessel extends from a main vessel, termed an “ostium,” the branch vessel typically has a tapered section extending from the main vessel into the branch vessel. When a lesion occurs within the ostium, placement of a stent can become difficult because of the tapered section. 
         [0005]      FIG. 1  illustrates a standard balloon catheter  100  inflated within an ostium  102  of a body lumen. The standard balloon catheter  100  is shown with a balloon  103  in an inflated state within the body lumen. The inflated state would typically be used to dilate the lumen and/or expand a stent (not illustrated). The body lumen has a tapered portion  104  in which a side branch  106  enters a main lumen  108 . The balloon  103  interacts with the tapered portion  104  of the side branch  106  causing a force in a proximal direction  112  of the side branch  106 . As a result, the balloon  103  may shift in the distal direction when fully inflated. This effect is dependent upon the magnitude of the taper and the length of the balloon  103  relative to the tapered portion  104 . This may result in the stent being positioned in a location different from what was originally intended. It would be beneficial to deliver and expand a stent within an ostium while avoiding the “watermelon seed effect” to ensure the proper placement of the stent. 
       SUMMARY 
       [0006]    In one embodiment of the invention a balloon catheter assembly comprises a catheter, a first balloon, a second balloon, a pressure actuated inflation valve, and a lumen extending from the proximal end of the catheter to the distal end of the catheter. The catheter has a proximal end and a distal end, and the first balloon is disposed at a distal portion of the catheter. The first balloon has a first interior volume. The second balloon is disposed at least partially proximal to the first balloon and has a second interior volume. The pressure actuated inflation valve is operably coupled to the second balloon and provides fluid communication through the inflation valve to the second interior volume when a threshold fluid pressure is exceeded in the first balloon. The lumen is in fluid communication with the first interior volume. 
         [0007]    In another embodiment a method for deploying a stent using a multi-phase inflation balloon assembly comprises guiding a distal end of the catheter to a treatment site having an ostial lesion in a body lumen. Fluid is provided to the first balloon to inflate the first balloon in a non-tapered portion of the body lumen. The inflated first balloon secures the catheter within the non-tapered portion of the body lumen. Fluid is then provided to the first balloon securing the catheter until the fluid pressure in the first balloon exceeds a threshold pressure actuating the pressure actuated inflation valve. Fluid is continues to be provided to the second balloon through the pressure actuated inflation valve to inflate the second balloon thereby expanding the stent. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    To further clarify the above and other advantages and features of the one or more present inventions, reference to specific embodiments thereof are illustrated in the appended drawings. The drawings depict only typical embodiments and are therefore not to be considered limiting. One or more embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0009]    The drawings are not necessarily to scale. 
           [0010]      FIG. 1  illustrates a standard balloon catheter being deployed proximate an ostium of a branch vessel. 
           [0011]      FIG. 2  illustrates an embodiment of a multistage balloon catheter for deploying a stent. 
           [0012]      FIG. 3  illustrates the embodiment of  FIG. 2  in an uninflated state. 
           [0013]      FIG. 4  illustrates the embodiment of  FIG. 2  with the distal balloon being inflated to expand a distal portion of a stent prior to expanding a proximal portion of the stent. 
           [0014]      FIG. 5  illustrates the embodiment of  FIG. 2  with both the proximal and distal balloons being inflated to expand a stent. 
           [0015]      FIG. 6  illustrates another embodiment of a multistage balloon catheter for deploying a stent. 
           [0016]      FIG. 7  illustrates the embodiment of  FIG. 6  in an uninflated state. 
           [0017]      FIG. 8  illustrates the embodiment of  FIG. 6  with the distal balloon being inflated. 
           [0018]      FIG. 9  illustrates the embodiment of  FIG. 6  with both the proximal and distal balloons being inflated to expand a stent. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    As used herein, “at least one,” “one or more,” and “and/or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C,” “at least one of A, B, or C,” “one or more of A, B, and C,” “one or more of A, B, or C” and “A, B, and/or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together. 
         [0020]    Various embodiments of the present inventions are set forth in the attached figures and in the Detailed Description as provided herein and as embodied by the claims. It should be understood, however, that this Detailed Description does not contain all of the aspects and embodiments of the one or more present inventions, is not meant to be limiting or restrictive in any manner, and that the invention(s) as disclosed herein is/are and will be understood by those of ordinary skill in the art to encompass obvious improvements and modifications thereto. 
         [0021]    Additional advantages of the present invention will become readily apparent from the following discussion, particularly when taken together with the accompanying drawings. 
         [0022]    In the following discussion, the terms “distal” and “proximal” will be used to describe the opposing axial ends of the inventive balloon catheter, as well as the axial ends of various component features. The term “distal” is used in its conventional sense to refer to the end of the apparatus (or component thereof) that is furthest from the operator during use of the apparatus. The term “proximal” is used in its conventional sense to refer to the end of the apparatus (or component thereof) that is closest to the operator during use. For example, a catheter may have a distal end and a proximal end, with the proximal end designating the end closest to the operator heart during an operation, such as a handle, and the distal end designating an opposite end of the catheter, such as treatment tip. Similarly, the term “distally” refers to a direction that is generally away from the operator along the apparatus during use and the term “proximally” refers to a direction that is generally toward the operator along the apparatus. 
         [0023]      FIG. 2  illustrates an embodiment of a multi-stage balloon catheter  200  having multiple balloons inflated. The multi-stage balloon catheter  200  is comprised of a catheter body  204  having a distal end  202  and a proximal end (not shown). The proximal end would typically extend out of a patient body during use and may terminate in a hub or other typical component. The catheter body  204  has a lumen  206  for delivering inflation fluid to a first inflation port  208  and a second inflation port  222 . In some embodiments, including the embodiment of  FIG. 2 , the catheter body  204  has an additional lumen  210  for receipt of a wire guide (not shown). The wire guide may be guided to a treatment site and then the catheter body  204  is advanced over the wire guide to position the distal end  202  of the catheter body  204  proximate the treatment site. 
         [0024]    The first balloon  214  has a first volume  218  and the second balloon  216  has a second volume  220 . Introduction of an inflation fluid into either of the volumes  218 ,  220  will inflate the respective balloon  214 ,  216  associated with that volume  216 ,  220 . The first port  208  provides fluid communication between the lumen  206  and the first volume  218  and the second port  222  provides fluid communication between the lumen  206  and the second volume  220 . A stent  224  is shown on the exterior of the balloons  214 ,  216  in an expanded state. 
         [0025]      FIG. 3  through  FIG. 5  illustrate the multi-stage balloon catheter  200  of  FIG. 2  being inflated within the ostium  102  of  FIG. 1 .  FIG. 3  illustrates the multi-stage balloon catheter  200  having the balloon s  214 ,  216  in an uninflated state. In typical use, the multi-stage balloon catheter  200  would be delivered to the treatment site in such a state. The multi-stage balloon catheter  200  may have a stent (not illustrated) disposed about at least a portion of the balloons  214 ,  216 . 
         [0026]      FIG. 4  illustrates the multi-stage inflation balloon catheter  200  having the first balloon  214  inflated. The first balloon  214  is located generally distal to the second balloon  216  and during use inflates prior to the inflation of the second balloon  216 . By inflating the distal balloon  214  first, the multi-stage balloon catheter  200  may be secured within the straight section of the branch vessel  106  prior to the second balloon  216  expanding in the tapered section  104 . The first balloon  214  is inflated to a pressure sufficient to secure the multi-stage inflation catheter  200  within the branch vessel  106 . Once the multi-stage inflation balloon catheter  200  is secured, the second balloon  216  inflates, expanding the stent in the tapered section  104 . The second balloon  216  may expand a stent in the tapered portion  104  of the branch vessel  106 . Because the first balloon  214  has already secured the multi-stage balloon catheter  200 , any interaction of the second balloon  216  and the tapered portion  104  is not likely to result in any significant movement of the catheter body  204  relative to the branch vessel  106 . 
         [0027]      FIG. 5  illustrates the second balloon  216  being inflated with the first balloon  214  inflated and in place. The outer surface of the second balloon  216  takes the tapered shape of the branch vessel  106 . Lateral movement of the multistage balloon catheter  200  caused by the interaction of the tapered portion  104  of the branch vessel  106  with the multistage balloon catheter  200  is minimized since the multistage balloon catheter  200  is anchored by the inflated first balloon  214  within the straight section of the branch vessel  106 . In this particular embodiment, the sequence of the balloons  214 ,  216  inflating may be controlled using a pressure sensitive inflation valve  230  disposed in the second inflation port  222 . The inflation fluid is first provided to the first volume  218  through the first port  208  until the first balloon  214  is inflated to a desired size. As the first balloon  214  inflated to secure the distal end of the stent, the fluid pressure will raise within the first volume  218 . Because the inflation fluid is typically a non-compressible liquid, the pressure will increase within the lumen as well. Once the first balloon  214  has sufficiently anchored the stent, the internal pressure is increased to actuate the pressure sensitive inflation valve  230 . The pressure sensitive inflation valve  230  may be a simple rupture disk that ruptures when the pressure exceeds a threshold pressure. Once the pressure sensitive inflation valve  230  opens, inflation fluid will flow through the pressure sensitive inflation valve  230  into the second volume  220 , expanding the proximal end of the stent as shown in  FIG. 5 . 
         [0028]    In another embodiment of a multistage balloon catheter  1000  shown in  FIG. 10 , a pressure sensitive inflation valve  1002  may be placed between a first balloon  1004  and a second balloon  1006 . The pressure sensitive inflation valve  1002  would extend from an inner volume  1008  of the first balloon  1004  to an inner volume  1010  of the second balloon  1006 . In such embodiments a second inflation port is not necessary, since the pressure sensitive inflation valve  1002  provides fluid communication between the first inner volume  1008  and the second inner volume  1006  when a threshold pressure is exceeded. In such embodiments the operator inflates the first balloon  1004  as previously described. The operator then continues to increase the pressure within the first balloon  1004  until the pressure sensitive inflation valve  1002  is activated, at which point the inflation fluid may pass from the first volume  1008  to the second volume  1010 . The second balloon  1006  will then begin to inflate after the first balloon  1004 . 
         [0029]      FIG. 6  illustrates another embodiment of a multi-stage balloon catheter  600  in an inflated state. The multi-stage balloon catheter  600  is comprised of a catheter body  604  having a distal end  602  and a proximal end (not shown). The proximal end would typically extend out of a patient body during use and may terminate in a hub or other typical component. The catheter body  604  has one lumen  606  for delivering inflation fluid to at least one inflation port  608 . In some embodiments, including the embodiment of  FIG. 6 , the catheter body  204  may have an additional lumen for placement over a wire guide (not shown). The wire guide may be guided to a treatment site and then the catheter body  604  is advanced over the wire guide to position the distal end  602  of the catheter body  604  proximate the treatment site. In the embodiment of  FIG. 6 , the catheter body  604  has  2  inflation ports  608 ,  610 . The first inflation port  608  provides a path for inflation fluid from the lumen  606  to a first balloon  614  and the second inflation port  610  provides a fluid path for inflation fluid to a second balloon  616  from the first lumen  606 . 
         [0030]    The distal end  602  of the catheter body  604  has a first balloon  614  and a second balloon  616  disposed thereon. The first balloon  614  has a first volume  618  and the second balloon  616  has a second volume  620 . The first balloon  614  is disposed within the second volume  620 . Introduction of an inflation fluid into either of the volumes  618 ,  620  will inflate the respective balloon  614 ,  616  associated with that volume  618 ,  620 . A stent (not illustrated) may be disposed on an outer surface of the balloon  614 ,  616  and is expanded by the inflated balloons. 
         [0031]      FIG. 7  through  FIG. 9  illustrate an embodiment of the multi-stage balloon catheter  600  of  FIG. 6  being inflated within the ostium  102  of  FIG. 1 .  FIG. 7  illustrates the multi-stage balloon catheter  600  having the balloon s  614 ,  616  in an uninflated state. In typical use, a guidewire  700  is guided to a treatment site and the multi-stage balloon catheter  600  is then delivered over the wire guide  700  to the treatment site in the uninflated state of  FIG. 7 . The multi-stage balloon catheter  600  may have a stent (not illustrated) disposed about at least a portion of the balloons  614 ,  616 . 
         [0032]      FIG. 8  illustrates the multi-stage inflation balloon catheter  600  having the first balloon  614  inflated. The first balloon  614  is located within the second volume  618  and distal to at least a portion of the second balloon  616 . The inflation of the first balloon  614  partially inflates the second balloon  616  since the first balloon  614  is in the second volume  618 . By inflating the first balloon  614  prior to the second balloon  616 , the multi-stage balloon catheter  600  may be secured within the straight section of the branch vessel  106  prior to the second balloon  616  expanding in the tapered section  104 . The first balloon  614  is inflated to a pressure sufficient to secure the multi-stage inflation catheter  600  within the branch vessel  106 . Once the multi-stage inflation balloon catheter  600  is secured, the second balloon  616  is expanded. The second balloon  616  may expand a stent in the tapered portion  104  of the branch vessel  106 . Because the first balloon  614  has already secured the multi-stage balloon catheter  600 , any interaction of the second balloon  616  and the tapered portion  104  is not likely to result in any significant movement of the catheter body  604  relative to the branch vessel  106 . 
         [0033]    The timing of the expansion of the first balloon  614  and the second balloon  616  is controlled by a pressure sensitive inflation valve in fluid communication with the second volume  620 . The first port  608  provides fluid communication between the first volume  618  and the inflation lumen  606 . A second port  610  provides fluid communication between the second volume  610  and the inflation lumen  606 . The pressure sensitive valve inhibits the fluid from flowing from the inflation lumen  606  into the second volume  620  until a threshold pressure is exceeded. The threshold pressure is greater than a pressure necessary for the first balloon  614  to inflate and secure the multistage balloon catheter  600  within the branch vessel. In some embodiments, the second port  610  may be omitted and a pressure sensitive inflation valve may be disposed in a wall of the first balloon  614 . When a threshold pressure in the first balloon  614  is exceeded, the pressure sensitive inflation valve will provide fluid communication from the first volume  618  to the second volume  620 . 
         [0034]      FIG. 9  illustrates the multistage balloon catheter  600  having both balloons  614 ,  616  inflated. The pressure sensitive inflation valve has actuated, allowing fluid communication between the first volume  618  and the second volume  620 . 
         [0035]    It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.