Abstract:
The specification discloses a cardiovascular ostial stents, a ostial stent balloon, and methods for their use. The stent includes two portions having different degrees of expandability. The distal portion has a normal degree of expandability to support a vessel. The proximal portion has a higher degree of expandability so that it can be formed into a flange-like structure. The balloon is designed to deploy the new stent in a single operation. The balloon includes first and proximal portions having different diameters corresponding to the first and proximal portions of the stent. The distal portion is of normal diameter to deploy the distal portion of the stent in the vessel. The proximal portion is of greater diameter to form the proximal portion of the stent into the flange-like structure. The method involves deploying a conventional stent through one branch of the bifurcation, and then deploying one of the novel stent through a wall of the first stent and into the other branch. The flange-like structure on the novel stent secures the novel stent within the conventional stent. Finally, a one-piece Y-shaped stent is provided for placement in a bifurcated artery.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to cardiovascular stents and to methods of using such stents.  
         [0002]     Cardiovascular stents are well known and are widely used in cardiovascular procedures. For example, a stent can be inserted into an artery after angioplasty to support the artery in its post-angioplasty size. Wherever used, the stents are delivered to the desired location while mounted on a balloon to facilitate movement through arteries. When the stent is in the desired location, the balloon is inflated to expand the stent and thereby deploy the stent to support the artery.  
         [0003]     A prior art stent  10  is illustrated in  FIG. 1 . The stent  10  includes a plurality of generally V-shaped struts  12  interconnected in a generally tubular configuration. The V-shaped struts are generally closed when the stent is collapsed (e.g. on a balloon), and the V-shaped struts are generally opened when the stent deployed. The spacing, thickness, and strength of the struts can be varied for different applications.  
         [0004]     A first exemplary deployment of the stent  10  is illustrated in  FIG. 2  in which a first or distal portion  14  of the stent is located within an ostial vessel  40  and a second or proximal portion  16  is located within the aorta  50 .  
         [0005]     A second exemplary deployment of the stent  10  is illustrated in  FIG. 3  in which the stent  10  is deployed in an ostial branch  40  extending from a primary vessel  50 . In this deployment, the end  18  of the stent  10  is aligned with the wall of the primary vessel  50 . This placement is particularly important if the lesion in the ostial vessel is close to the primary vessel  50 . If the stent  10  is deployed too far into the ostial vessel, the lesion may not be properly supported, possibly leading to complications. On the other hand, if the stent  10  extends into the primary vessel  50 , the stent can interfere with other or further intervention in that region. Consequently, the accurate placement and deployment of the stents is critical. However, even when properly deployed, a single stent is incapable of supporting all portions of a bifurcation or Y.  
       SUMMARY OF THE INVENTION  
       [0006]     The aforementioned problems are overcome in a first embodiment in which an cardiovascular stent is provided with two different radial expansion or distortion capabilities along its length. More specifically, the stent includes a first or distal portion capable of generally conventional expansion to support the artery in which the distal portion is located. The stent includes a second or proximal portion that remains outside of the ostial vessel. The proximal portion is capable of enhanced expansion, for example, up to a degree generally perpendicular to the axis of the stent to form a flange against the wall of the primary vessel.  
         [0007]     In a second embodiment of the invention, a novel ostial balloon is provided for deploying the new stent. The balloon includes two portions having different diameters and shapes when the balloon inflated. Specifically, the balloon includes a distal portion that expands to a conventional diameter to deploy the distal portion of the stent within the ostial vessel. The balloon includes a proximal portion that expands to a substantially greater diameter to force the proximal longitudinal portion of the stent into its flange-like configuration.  
         [0008]     In a third embodiment of the invention, the new stent of the first embodiment is used in conjunction with a conventional stent to provide full support through a bifurcation. The process includes the steps of (1) deploying a conventional stent through one branch of the bifurcation, (2) inserting the new stent through the wall of the primary stent and into the other branch of the bifurcation, (3) deploying the new stent so that the distal portion of the stent supports the other branch and the proximal portion of the stent forms a flange against the interior wall of the conventional stent.  
         [0009]     In a fourth embodiment of the invention, a one-piece unitary stent includes an inlet portion and two outlet portions. Accordingly, the stent may be deployed in a bifurcation to fully support all three vessels meeting in the bifurcation.  
         [0010]     The novel stents, balloon, and method have several advantages. First, the stents are more securely held in position and therefore are less subject to movement or other complications following deployment. Second, the stents and method are capable of more fully supporting plaques that are located at and through branches and bifurcations. Third, the stents and methods result in deployment that is more accurate, simple, and effective.  
         [0011]     These and other objects, advantages, and features of the invention will be more fully understood and appreciated by reference to the description of the preferred embodiments and the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a side view of a prior art stent in the deployed or expanded position;  
         [0013]      FIG. 2  is a side view of the prior art stent deployed in an ostial vessel extending from the aorta;  
         [0014]      FIG. 3  is a side view of the prior art stent deployed in an ostial side branch vessel;  
         [0015]      FIG. 4A  is a perspective view of the stent of the present invention;  
         [0016]      FIG. 4B  is a side view of one group of struts;  
         [0017]      FIG. 4C  is an enlarged view showing the strut structure of the stent;  
         [0018]      FIG. 5  is a side view of the stent deployed in an ostial vessel;  
         [0019]      FIG. 6  is an end view of the deployed stent taken along line  6  in  FIG. 5 ;  
         [0020]      FIG. 7  is a side view of the stent deployed in an ostial branch;  
         [0021]      FIG. 8  is an end view of the deployed stent taken along line  8  in  FIG. 7 ;  
         [0022]      FIG. 9  is a side view of a prior art balloon when inflated;  
         [0023]      FIG. 10  is a side view of the ostial balloon of the present invention when fully inflated;  
         [0024]      FIG. 11  is a side view of the stent mounted on a deflated balloon on a guide wire;  
         [0025]      FIG. 12A  is a side view of the balloon partially inflated to begin deploying the stent;  
         [0026]      FIG. 12B  is a side view of the balloon fully inflated to complete deploying the stent;  
         [0027]      FIG. 13  is an illustration of a bifurcation with plaques;  
         [0028]      FIG. 14  shows conventional angioplasty balloons within the bifurcation;  
         [0029]      FIG. 15  shows a stent extending through the bifurcation and into one of the two branches;  
         [0030]      FIG. 16  shows an inflated balloon forming an opening in the wall of the stent illustrated in  FIG. 15 ;  
         [0031]      FIG. 17  is a sectional view taking along line  17 - 17  in  FIG. 16 ;  
         [0032]      FIG. 18  is a sectional view similar to  FIG. 17  showing the balloon deflated;  
         [0033]      FIG. 19  shows the ostial stent extending through the opening in the first stent;  
         [0034]      FIG. 20  shows the ostial balloon inflated to deploy the ostial stent;  
         [0035]      FIG. 21  shows the post-procedure bifurcation supported by both the first stent and the ostial stent;  
         [0036]      FIG. 22  is a end view of the ostial stent taken along line  22  in  FIG. 21 ;  
         [0037]      FIG. 23  shows the bifurcated stent of the present invention mounted on a pair of guide wires;  
         [0038]      FIG. 24  shows the bifurcated stent on the guide wires that extend into the two branches;  
         [0039]      FIG. 25  shows the bifurcated stent separated over the two guide wires extending into the branches;  
         [0040]      FIG. 26  shows the bifurcated stent immediately prior to deployment;  
         [0041]      FIG. 27  shows the bifurcated stent fully deployed; and  
         [0042]      FIG. 28  is a schematic illustration of the aorta and primary arteries showing the locations where the stents of the present invention might be deployed.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0000]     I. Ostial Stent  
         [0043]     An ostial stent constructed in accordance with a preferred embodiment of the invention is illustrated in  FIGS. 4-8  and generally designated  100 . The stent includes a generally distal portion  110  and a generally proximal portion  120 .  
         [0044]     The struts  112  in the stent  100  are uniformly spaced along the length of the stent  100 . In other words, the distance between any two struts  112  is equal. However, the lengths of the struts  112  vary along the length of the stent  100 . The struts are shortest at the extreme distal end  100   d , and the struts are longest at the extreme proximal end  100   p . In the preferred embodiment, the length of each strut is longer than the strut on one side and shorter than the strut on the other side, so that the length of the struts  112  increases from the extreme distal end  100   d  to the extreme proximal end  100   p.    
         [0045]     Each of the struts is V-shaped. Because the struts vary in length, the Vs form different angles depending on the length of the strut. When the stent  100  is collapsed (as illustrated in  FIG. 4A ), the relatively short struts in the distal portion  110  form relatively large angles, and the relatively long struts in the proximal portion  120  form relatively small angles.  
         [0046]     The two portions  110  and  120  therefore are capable of different radial expansions or distortions. The distal portion  110  is expandable to a degree in the range of prior art stents. Consequently, the distal portion  110  is suited for supporting a vessel. The proximal portion  120  is expandable to a far greater degree than that of the distal portion  110 . Specifically, the proximal portion  120  may be expanded until it is generally perpendicular to the axis of the stent thereby forming a flange on the distal portion  110 .  
         [0047]      FIG. 4C  is an enlarged view showing more specifically the presently envisioned structure for the struts  112 . Arrows  130  and  140  show the direction of movement of the strut portions  112   a  and  112   b  respectively as the stent expands. The two directions are opposite one another. The specific  FIG. 4C  structure enables the struts  112  to be uniformly spaced (i.e. the distance between adjacent struts is constant).  
         [0048]     The disclosed stent  100  is but one example for constructing a strut having different degrees of expandability or distortion along its length. The length of the struts can vary in a fashion other than as described. Further, other techniques for providing different portions or areas of expansion or distortion will be known to those skilled in the art.  
         [0049]     A circumferential marker (not illustrated) is located on the outer wall of the stent in conventional fashion to assist the physician in properly locating the stent during the procedure.  
         [0050]     The stent  100  provides significant flexibility, accommodates angled vessels without losing the integrity of the stent, and enables deployment of the stent in vessels whose diameters vary along the location of the stent.  
         [0051]      FIGS. 5-6  illustrate the deployment of the stent  100  within an ostial branch  150  extending from a primary vessel  160 . The distal portion  110  of the stent is located within the branch  150 , and the proximal portion  120  is flared outwardly to form a flange against the interior wall of the primary vessel  160 . When so deployed, the distal portion  110  supports the vessel  150 . The flange  120  assists in maintaining the stent  100  in proper position subsequent to the catheterization procedure.  
         [0052]      FIGS. 7-8  show the stent  100  deployed in an ostial branch  170  extending from a primary vessel  180 . The distal portion  110  of the stent  100  is located within the ostial branch  170  to support the branch. The proximal portion  120  is flared outwardly to form a flange against the interior wall of the ostial vessel  180 . The marker is aligned with the wall of the primary vessel  180 .  
         [0053]     The ostial stent can be mounted on a conventional balloon for deployment in “straight” vessels. The struts for straight stents would have an angulation in the approximate range of 45 degrees to 55 degrees in comparison to the approximate range of 30 degrees to 60 degrees in the above described ostial stent. The greater angulation provides appropriate support for proximal vessel walls.  
         [0000]     II. Ostial Balloon  
         [0054]     A prior art stent balloon  200  is illustrated in  FIG. 9 . The prior art balloon is ovoid or cigar-shaped when inflated as illustrated in  FIG. 9 . As is well known in the art, the stent is mounted over the deflated balloon before the stent/balloon combination is delivered to the desired location. When the stent is properly positioned, the balloon is inflated to expand or deploy the stent into its operative configuration. The prior art balloon  200  is incapable of fully deploying the stent  100 . Specifically, the prior art balloon  200  cannot expand the proximal portion  120  of the stent  100  into its flange-shaped configuration.  
         [0055]     An ostial balloon constructed in accordance with a preferred embodiment of the invention is illustrated in  FIGS. 10-12  and generally designated  200 . The balloon includes a first longitudinal portion  210  and a second longitudinal portion  220 . The first longitudinal portion when fully inflated ( FIG. 12B ) is essentially ovoid as in the prior art. The second portion  220  is bulbous when fully inflated, and has a diameter substantially greater than that of the distal portion  210 . The first and second portions  210  and  220  are integrally connected to one another. Consequently, inflation of the balloon  200  results in inflation of both portions  210  and  220 . Methods and techniques for fabricating the balloon will be known to those skilled in the art.  
         [0056]     The stent  100  is shown in  FIG. 11  in its collapsed condition mounted over a balloon (not visible) on a guide wire  230 . As is well known to those skilled in the art, the guide wire  230  is used to guide the stent  100  to the deployment location.  
         [0057]      FIGS. 12A  and B illustrate the ostial balloon  200  at two different stages of inflation to deploy the stent  100 .  FIG. 12A  shows the first balloon portion partially inflated, and  FIG. 12B  shows the first balloon portion fully inflated.  FIG. 12A  illustrates the initial inflation of the balloon in which the distal end of the distal portion is inflated and in which the proximal portion is inflated. As inflation continues, the balloon inflates toward the center from the opposite ends. When full inflated ( FIG. 12B ), the distal portion  210  of the balloon deploys the distal portion  110  of the stent  100 . The described inflation sequence traps all plaques within the stent, preventing a distal embolization. Similarly, the proximal portion  220  of the balloon deploys the proximal portion  120  of the stent  100 . Because the distal portion  210  is substantially similar in size and shape to the prior art stent  201  (see  FIG. 9 ), this portion of the balloon properly deploys the supportive portion  110  of the stent  100  within the ostial branch  170 . Because the proximal portion  220  has a diameter substantially greater than that of the distal portion  210 , and further because of its bulbous shape as it inflates, the proximal portion  220  forms the proximal portion  120  of the stent into a flange against the wall of the main branch  180 .  
         [0000]     III. Procedure Using Both Conventional Stent and the New Ostial Stent  
         [0058]     The ostial stent  100  can be used in conjunction with a conventional stent  10  (or another ostial stent) to fully support a bifurcation or branch in which an incoming vessel and two outgoing vessels meet in a Y. Further, the procedure results in a combination device that fully support all areas within and through the bifurcation.  
         [0059]     A bifurcation  300  is illustrated in  FIG. 13 . The bifurcation includes an incoming or main branch  310  and two outgoing or extending branches  320  and  330 . As disclosed, plaques  340  might exist in any or all of the variety of areas illustrated.  
         [0060]     The first step in treating the plaques is conventional kissing angioplasty as illustrated in  FIG. 4 . A pair of conventional balloons  201  are inserted using guide wires  230  and  230 ′ in conventional fashion. The balloons are inflated to perform the angioplasty and to restore the branches  310 ,  320  and  330  to their original diameters. The angioplasty balloons are then deflated and withdrawn.  
         [0061]     A conventional stent  10  (or an ostial stent as described in this application) is subsequently inserted and deployed as illustrated in  FIG. 15 . The stent  10  extends through the bifurcation from the incoming branch  110  to the outgoing branch  320 . When so deployed, the second branch  330  is closed by the stent  10 .  
         [0062]     The guide wire  230 ′ is then withdrawn from the branch  330  and is advanced into the stent  110 , through the wall (between the struts  112 ) of the stent  10 , and into the branch  330 . A conventional balloon  201  (or an ostial balloon as described in this application) is then positioned on the wire  230 ′ and through the wall of the stent  10 . If a new ostial stent is used, rather than a conventional stent, the balloon can be more easily inserted between the struts. The balloon  201  is then inflated or expanded. The procedure at this point is illustrated in  FIG. 16-17 . The inflated balloon creates an opening  140  through the wall of the stent  10  by moving the struts. The diameter of the opening  140  is approximately the same as the diameter of the branch  330 .  
         [0063]     The balloon  200  is then deflated as illustrated in  FIG. 18 . The opening  140  remains the same size as created by the balloon. The balloon then is withdrawn from the conventional stent  10 .  
         [0064]     The next step is to position an ostial stent  100  in the opening  140  through the wall of the conventional stent  10 . The result of this step is illustrated in  FIG. 19 . The distal portion  110  of the stent is located within the branch  330  and the proximal portion  120  of the stent is located within the conventional stent  10 .  
         [0065]     The balloon  200  on which the stent  100  is mounted is then inflated as illustrated in  FIG. 20 . When the balloon is fully inflated, the distal portion  110  of the stent is expanded or deployed to support the branch  330 , and the proximal portion  220  of the balloon forces the proximal portion  120  of the stent into a flange-like configuration against the wall of the conventional stent  10 . The balloon  200  and both wires  230  and  230 ′ are then withdrawn so that the final result is as illustrated in  FIGS. 21 and 22 .  
         [0066]     The resulting two-stent combination fully supports all areas in and through the entire bifurcation. The method therefore provides previously unavailable treatment in a relatively simple but effective procedure.  
         [0000]     IV. One-Piece Bifurcated Stent  
         [0067]     A one-piece, unitary stent for deployment in a bifurcation is illustrated in  FIGS. 23-27  and generally designated  400 . The stent includes an inlet portion  410  and two outlet (or ostial) portions  420  and  430 . The three portions form a Y. All of the portions  410 ,  420  and  430  are part of a single integrated whole. Methods and techniques fabricating the stent  400  will be apparent to those skilled in the art.  
         [0068]     The bifurcated stent  400  is deployed in a bifurcation  300  as illustrated in  FIGS. 24-27 .  FIG. 24  shows the stent  400  mounted on the guide wires  230  and  230 ′. The guide wire  230  extends through portions  410  and  420 , and the guide wire  230 ′ extends through portions  410  and  430 .  
         [0069]      FIG. 25  shows the two portions  420  and  430  following the guide wires  230  and  230 ′ respectively into the branches  320  and  330  respectively.  
         [0070]      FIG. 26  shows the position of the stent  400  just prior to deployment. The three stent portions  410 ,  420 , and  430  are positioned within the three branches  310 ,  320 , and  330  respectively.  
         [0071]      FIG. 27  shows the stent  400  following deployment. The three stent portions  410 ,  420 , and  430  support the respective bifurcation portions  310 ,  320  and  330 .  
         [0072]     The balloon (not shown) for deploying the stent  400  is Y-shaped. Its construction and fabrication will be apparent to those skilled in the art.  
         [0000]     IV. Conclusion  
         [0073]      FIG. 28  is a schematic illustration of the aorta and primary arteries showing some of the possible locations  50  in which the stents of the present invention might be deployed. As can be seen, the possible locations are widespread and varying.  
         [0074]     The above described stents and procedures enhance and expand cardiovascular procedures. The stents and procedures are highly effective and enable a variety of new areas, such as bifurcations, to be stented. The stents are less subject to movement and other subsequent complications.  
         [0075]     The above descriptions are those of current embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention, which are to be interpreted in accordance with the principles of patent law including the Doctrine of Equivalents.