Abstract
Systems and methods for deploying one or more stents within a bifurcated vessel are disclosed. A bifurcation-stent can include a main-branch portion and first and second side-branch portions each mechanically attached to the main-branch portion. The first and second side-branch portions are mechanically attached together at a branch point proximate the distal end of the main-branch portion. The bifurcation-stent can be disposed on two balloon catheters for deployment to a bifurcation. The bifurcation-stent is advanced within a main branch until it reaches the carina of the bifurcation, such as when the branch point abuts the carina. The bifurcation-stent can be deployed by inflating the balloon catheters such that the main-branch portion is disposed in the main vessel and the first and second side-branch portions are disposed in separate, respective side branches of the bifurcation.
Claims
1. A device, comprising: a bifurcation-stent comprising: a main-branch portion; a first side-branch stent mechanically attached to the main-branch portion at a first laterally exterior point of a distal end of the main-branch portion, wherein the first side-branch and the main-branch are only attached at the first laterally exterior point; and a second side-branch portion mechanically attached to the main-branch portion at a second laterally exterior point of the distal end of the main-branch portion, wherein the main-branch portion and each of the side-branch portions are separate stents that are coupled together, wherein the second side-branch portion and the main-branch portion are only attached at the second laterally exterior point, wherein the first side-branch portion is mechanically attached to the second side-branch stent portion at a laterally interior point proximate the distal end of the main-branch portion, and wherein the first side-branch portion and the second side-branch portion are only attached at the laterally interior point.
2. (canceled)
3. The device of claim 1, wherein the main branch stent portion is mechanically attached to the first side-branch portion by a first weld at the first laterally exterior point, the main-branch portion is mechanically attached to the second side-branch portion by a second weld at the second laterally exterior point, and the first-side branch portion is mechanically attached to the second side-branch portion by a third weld proximate to the laterally interior point.
4. (canceled)
5. (canceled)
6. The device of claim 1 further comprising: a first balloon catheter; and a second balloon catheter, wherein: the main-branch portion positioned on and around both the first balloon catheter and the second balloon catheter, the first side-branch portion being positioned on and around the first balloon catheter only, and the second side-branch portion being positioned on and around the second balloon catheter only.
7. The device of claim 6, wherein: the first balloon catheter having a first lumen configured to receive a first guide wire and disposed within the first balloon catheter; and the second balloon catheter having a second lumen configured to receive a second guide wire and disposed within the second balloon catheter.
8. A device, comprising: a stent comprising: a first stent portion; a second stent portion; and a third stent portion, wherein the first stent portion, the second stent portion and the third stent portion are separate from each other but are coupled together, wherein each of the second stent portion and the third stent portion being permanently attached to the first stent portion only at separate laterally exterior points on a distal end of the first stent portion and the second stent portion and third stent portion are permanently attached only at a proximal end of the second stent portion and a proximal end of the third stent portion; a first balloon catheter; and a second balloon catheter, the first stent portion being positioned on and around both the first balloon catheter and the second balloon catheter, the second stent portion being positioned on and around the first balloon catheter only, and the third stent portion being positioned on and around the second balloon catheter only.
9. (canceled)
10. The device of claim 8, wherein the first stent portion is permanently attached to the second stent portion by a first weld between the first stent portion and the second stent portion, the first stent portion is permanently attached to the third stent portion by a second weld between the first stent portion and the third stent portion, and the second stent portion is permanently attached to the third stent portion by a third weld between the second stent portion and the third stent portion.
11. (canceled)
12. (canceled)
13. The device of claim 8, wherein: the first balloon catheter has a first lumen configured to receive a first guide wire and disposed within the first balloon catheter; and the second balloon catheter has a second lumen configured to receive a second guide wire and disposed within the second balloon catheter.
14. A method, comprising: deploying a bifurcation-stent to a vessel bifurcation, wherein the bifurcation-stent comprises: a main-branch portion, a first side-branch portion mechanically attached to the main-branch portion, and a second side-branch portion mechanically attached to the main-branch portion, the first side-branch portion being mechanically attached to the second side-branch portion at a branch point, and wherein, after being deployed: the main-branch portion is disposed in a main vessel of the bifurcation, the first side-branch portion is disposed in a first side-branch vessel of the bifurcation, the second side-branch portion is disposed in a second side-branch vessel of the bifurcation, and the branch point abuts a carina of the bifurcation.
15. The method of claim 14 further comprising: inserting a first guide wire through the main vessel of the bifurcation and into the first side branch vessel of the bifurcation; and inserting a second guide wire through the main vessel of the bifurcation and into the second side branch vessel of the bifurcation.
16. The method of claim 15, wherein deploying the bifurcation-stent comprises: advancing a first balloon catheter along the first guide wire to the bifurcation and a second balloon catheter along the second guide wire to the bifurcation, wherein during advancing the first balloon catheter and the second balloon catheter, the main branch stent portion is disposed on and around the first balloon catheter and the second balloon catheter, the first side branch stent portion is disposed on and around the first balloon catheter, and the second side branch stent portion is disposed on and around the second balloon catheter.
17. The method of claim 16, wherein the first balloon catheter traverses the first guide wire and the second balloon catheter traverses the second guide wire until the branch point abuts the carina of the bifurcation.
18. The method of claim 16 further comprising, after advancing the first balloon catheter and the second balloon catheter: inflating the first balloon catheter; and inflating the second balloon catheter.
19. The method of claim 14, wherein: the main branch stent portion is a separate stent from each of the first side-branch portion and the second side-branch portion, the main-branch portion is mechanically attached to the first side-branch portion by a first weld, the main branch stent portion is mechanically attached to the second side-branch portion by a second weld, and the first side-branch portion is mechanically attached to the second side-branch portion by a third weld at the branch point.
20. The method of claim 14, wherein the main-branch portion is integrally formed with the first side-branch portion, the main-branch portion is further integrally formed with the second side-branch portion, and the first side-branch portion is mechanically attached to the second side-branch portion by a weld at the branch point.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Reference will now be made to the accompanying drawings, wherein:
[0022] FIG. 1 is a diagram of a bifurcated vessel.
[0023] FIGS. 2A-E are diagrams of dual-lumen balloon catheters according to some embodiments.
[0024] FIG. 3 is a cross-sectional view of the balloon catheter according to some embodiments.
[0025] FIGS. 4A-H are diagrams of bifurcation stent delivery devices according to some embodiments.
[0026] FIG. 5 is a flowchart of a bifurcation stent delivery technique according to some embodiments.
[0027] FIG. 6 is a diagram of a bifurcation stent delivery device introduced into a main branch toward a bifurcation lesion according to some embodiments.
[0028] FIG. 7 is a diagram of the bifurcation stent delivery device positioning a stent at the carina of the bifurcation according to some embodiments. The wire under the stent locates the carina precisely.
[0029] FIG. 8 is a diagram of the bifurcation stent delivery device deploying the stent precisely at the carina according to some embodiments.
[0030] FIG. 9 is a diagram of the stent with the balloon removed and the expanded stent accurately positioned across the carina according to some embodiments.
[0031] FIG. 10 is a diagram of kissing balloons used to splay the stent across the carina according to some embodiments.
[0032] FIG. 11 is a diagram of the stent fully splayed across the carina according to some embodiments.
[0033] FIGS. 12A and 12B are diagrams of three stents being positioned at the bifurcation according to some embodiments. FIG. 12B demonstrating the final results of the creation of a true pantaloons bifurcation stenting configuration.
[0034] FIGS. 13A and 13B are simplified diagrams of an open-cell and a closed-cell stent according to some embodiments.
[0035] FIG. 13C is a diagram of a bifurcation stent delivery device employing a single-lumen catheter, according to some embodiments. Here the second wire is trapped under the stent by crimping the stent over it. The distal edge of the stent is located at the distal tapered edge of the balloon, unlike from the industry standard.
[0036] FIG. 14 is a flowchart of a bifurcation stent delivery device assembly using a single-lumen catheter with a closed-cell stent according to some embodiments.
[0037] FIG. 15 is a flowchart of a bifurcation stent delivery device assembly using a single-lumen catheter with an open-cell stent according to some embodiments. The stent is removed without inflating the balloon.
[0038] FIGS. 16A-C are diagrams of alternative delivery devices according to some embodiments.
[0039] FIGS. 17A-B illustrate a three-stent delivery device according to an alternative embodiment.
[0040] FIGS. 18A-C illustrate a single bifurcation-stent delivery device.
[0041] FIGS. 19A-B illustrate a single bifurcation-stent delivery device according to an alternative embodiment.
[0042] FIGS. 20A-B illustrate a single bifurcation-stent delivery device according to an alternative embodiment.
[0043] FIGS. 21A-B illustrate a single bifurcation-stent delivery device according to an alternative embodiment.
[0044] FIGS. 22A-B illustrate a single bifurcation-stent delivery device according to an alternative embodiment.
[0045] While this specification provides several embodiments and illustrative drawings, a person of ordinary skill in the art will recognize that the present specification is not limited only to the embodiments or drawings described. It should be understood that the drawings and detailed description are not intended to limit the specification to the particular form disclosed, but, on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the claims. Also, any headings used herein are for organizational purposes only and are not intended to limit the scope of the description. As used herein, the word “may” is meant to convey a permissive sense (i.e., meaning “having the potential to”), rather than a mandatory sense (i.e., meaning “must”). Similarly, the words “include,” “including,” and “includes” mean “including, but not limited to.”
DETAILED DESCRIPTION
[0046] This specification discloses systems and methods for accurately deploying stents within bifurcated vessels. Examples of “bifurcated vessels” include, but are not limited to, bifurcated blood vessels (coronary, carotid, iliac, or other blood vessels), tracheobronchial trees, venous systems, ureters, etc. Although the embodiments discussed below occasionally refer to specific types of vessels (e.g., blood vessels), it should be understood that these examples of intravascular stents are provided for sake of illustration only, and not by way of limitation. Moreover, it should be noted that the various embodiments illustrated in the figures and discussed below are not necessarily drawn to scale, but are instead presented with dimensions intended facilitate their understanding.
[0047] In various embodiments, the methods described herein include deploying a stent at the main branch of a bifurcated vessel by positioning the stent accurately at the carina of the bifurcation while maintaining access to one or more side branches, and then deploying one or more additional stents in the side branches of the bifurcation. In some implementations, various ones of the stents may be deployed sequentially or simultaneously, while in some examples, the main-branch and side-branch stents may be mechanically attached and deployed as a single stent.
[0048] In some implementations, these methods may be performed by employing at least two distinct types or groups of stent delivery devices. A first group of devices includes a balloon catheter manufactured with two or more lumens or channels configured to accommodate two or more separate guide wires (i.e., a dual-lumen catheter as shown in FIGS. 2A-D, or a triple-lumen catheter, as shown in FIG. 2E). The pre-manufactured models may include multiple balloons in some embodiments. A second group of devices includes alternatives to the pre-manufactured dual-lumen catheter. An existing single-lumen balloon catheter may be modified so that it is capable of performing the same or similar operations as the pre-manufactured models. For example, a secondary guide wire may be placed between the stent and a single-lumen balloon catheter in an “off-label” procedure (e.g., FIG. 13C). Additionally or alternatively, a dual-balloon configuration with a single stent crimped over two balloons may be designed to help position the stent at the carina (e.g., FIG. 16A). Additionally or alternatively, a stent may be crimped over a combination of a balloon catheter and a long tube catheter with an approximately 0.014-inch wire lumen or the like to facilitate accurate delivery at the carina while maintaining dual side branch access through the stent lumen (e.g., FIGS. 16B and 16C). In some implementations, a group of stents and/or multiple stent portions attached together as a single stent may be configured over two balloons to help position the group of stents or single stent at the carina (e.g., FIGS. 17A, 18A). These various devices, as well as their corresponding manufacturing and delivery methods, are described in turn below.
Stent Delivery with Multi-Lumen Balloon Catheters
[0049] In some embodiments, stent delivery devices may employ balloon catheters manufactured with two or more lumens (the first group or type of devices described above). For example, in a dual-lumen configuration, a main lumen may be located in the axial center of the balloon shaft, and may be configured to house a main guide wire. A secondary lumen may be located along the side of the balloon shaft, and may be configured to house a secondary guide wire. The exit point for the secondary lumen may be at the distal end of the balloon, and may occur where the balloon tapers—i.e., at or near a “shoulder region” of the balloon. This secondary guide wire may maintain access to a side branch of a bifurcated vessel during a stent deployment procedure. In some embodiments, three stents may be deployed, one in each branch of the bifurcation. The device may maintain a low profile to ensure that it fits in the entity being treated (e.g., a coronary vessel or other type of vessel). The stent(s) may be chosen, for example, based on the size of the vessel and the length of the lesion.
[0050] In various embodiments, the stent may be positioned on the balloon so that the stent is at the shoulder of the balloon, just as the balloon tapers. As the inventor hereof has discovered, when the balloon is inflated for stent expansion, the portion of the balloon distal to the stent should immediately taper and the balloon should not push the stent back from its desired location within the vessel directly at the carina. In contrast, conventional stent delivery systems typically place the stent in the center or middle of the balloon, with a ˜0.5 to 1 mm of balloon extending or “overhanging” proximal and distal to the stent. The distal portion of the balloon beyond the distal edge of the stent is generally larger than either side branch. During stent inflation, the ends of the balloon that are not covered by the stent expand first. Since side branches are generally smaller than the main branch, when there is a size mismatch of the distal balloon with respect to the size of the side branch vessel, the distal balloon-end expansion in a conventional delivery system invariably displaces the stent backwards away from the carina. Again, at least in part because certain of the techniques described herein allow accurate positioning of the stent at the carina of the bifurcation, these techniques represent a significant improvement/modification over conventional delivery systems. Conventionally, because of branch vessel overlap, it is difficult to identify the true bifurcation. The bifurcation seen by angiography may not accurately correspond to the true anatomical bifurcation. This difficulty is overcome by the technique described herein, because the anatomical bifurcation is physically and positively identified. This not only guarantees that the stent is placed accurately at the bifurcation, it also saves the patient from being exposed to additional contrast and radiation.
[0051] A 0.014-inch guide wire or the like may be placed in each lumen or channel of the balloon. The assembled device may be placed in the vessel using the main guide wire. As the device moves along main guide wire through the vessel, the secondary guide wire may be guided into a side branch. The device may be advanced, for example, until it naturally stops at the carina of the bifurcation due to the secondary wire positioned into the side branch. Hence the term “carina locator”. At this point, the operator may know or sense that the device is positioned accurately at the carina. For example, the secondary wire in the second side branch may be observed to buckle slightly and a resistance to forward progress of the stent will be felt physically by the operator. Additionally, or alternatively, radiolucent markers or the like on the balloon shaft, stent, and/or distal tip of the tube or channel under the stent may facilitate positioning of the balloon during this procedure. Also, in some cases, the un-inflated stent may have a distal marker or may be more visible because it is not inflated and/or because it is more radiolucent, as is the case of platinum chromium stents (e.g., ION® or PROMUS® stents).
[0052] The balloon catheter may then be inflated and the stent deployed. In this manner, access to the side branch and main branch within the lumen of the stent may be maintained with the two guide wires. Next, a first kissing balloon technique may be used to splay the stent to conform to the bifurcation. The two balloons may be sized as per the approximate diameters of each side branch so as to splay the stent appropriately without damaging the side branches. Once the kissing balloons have been inflated, the stent in the main branch may be splayed across the carina. Thereafter, stents of the appropriate size may be deployed in a kissing manner into the side branches of the bifurcations. These two stents may be positioned so that the proximal part of the respective stents is exactly at the carina. A second kissing balloon technique may be used to further inflate the branch stents and the main vessel stent, and further cause opposition of the stents into the intima of the vessel. High-pressure inflations may be used.
[0053] For sake of illustration, a typical procedure for kissing stents deployment may be conducted as follows. When one of the kissing balloons is inflated to approximately ˜10-16 atm, the other balloon may be inflated to approximately ˜3-4 atm (and vice versa for the other stent). Thereafter, both balloons may be brought down to approximately ˜5-8 atm and deflated at the same time to ensure that the carina is correctly positioned. It should be understood, however, that the inflation pressures to be used are dependent on the size of the vessel, the compliance of the inflating balloons, manufacturer recommendations, etc. In the dual balloon stent configuration, for example, the two balloon sizes selected may be small enough to not damage the main vessel and yet capable of pre-dilating the distal side branches to facilitate the kissing stents to follow.
[0054] In various applications, a stent delivery device may be used to deploy stents designed to treat stenosis and/or other vessel conditions. Techniques for deploying these stents accurately at bifurcated lesions are described below.
[0055] Turning now to FIG. 1, a diagram of a bifurcated vessel is depicted. Generally, the lengths and diameters of the various elements of bifurcated vessel 100 may vary depending upon their location in a patient's body. As illustrated, bifurcated vessel 100 includes main branch 110, which splits between side branches 120A-B. Carina 130 represents a region of bifurcated vessel 100 where side branches 120A-B are joined together. In some cases, carina 130 may also be referred to as a “vertex” or “crotch point” of bifurcated vessel 100. Plaque 140 is illustrated along the surfaces or walls of bifurcated vessel 100 to represent stenosis or other types of lesions.
[0056] FIG. 2A is a diagram of a dual-lumen balloon catheter according to some embodiments. In particular, balloon catheter 200A may include proximal tapered end 210 and distal tapered end 220. Catheter 200A may also include main or primary guide wire lumen (or channel) 230 as well as side or secondary guide wire lumen (or channel) 240. Main guide wire lumen 230 may include exit 250, and may be configured to receive a first guide wire (i.e., a main or primary guide wire—not shown) through main wire port 201. Conversely, side guide wire lumen 240 may include end 260, and may be configured to receive another guide wire (i.e., a side or secondary guide wire—not shown) through second wire port 202. Balloon inflation port 203 may be utilized deliver dilute contrast or another suitable fluid to lumen 280 or chamber 281 so as to inflate catheter 200A during a delivery procedure. In some cases, lumen 280 or chamber 281 may at least partially surround main guide wire lumen 230.
[0057] As illustrated in FIG. 2A, exit 250 of main lumen 230 through shaft portion 251 may be located at or near the center portion (i.e., the axis) of catheter 200A, whereas end 260 of side lumen 240 may be located at or near (e.g., immediately after) proximal edge 270 of distal shoulder region 220 of catheter 200A. It may also be noted that catheter 200A tapers between proximal edge 270 of distal shoulder region 220 (or end 260) and distal edge 271 of distal shoulder region 220, which is where the balloon joins shaft 251 in an approximately conical tapered fashion. Accordingly, proximal edge 270 of distal shoulder region 220 may sometimes be referred to as a “tapered edge,” “tapered shoulder,” or “shoulder” of catheter 200A.
[0058] In some embodiments, proximal edge 270 may be defined as the point along catheter 200A where it begins to taper into region 220. And in some cases, end 260 may be located exactly at proximal edge 270. In other cases, end 260 may be located at a distance from proximal edge 270 so that lumen 240 ends before edge 270 or extends beyond edge 270.
[0059] The individual guide wires may be placed through the main vessel and into the two side branches of the bifurcation before the dual lumen stent balloon is loaded. In this case, the guide wires should not be twisted around each other, which would obstruct the movement of the stent balloon as it travels along the guide wires and through the main vessel to the carina location. In some cases, the dual lumen catheter in the configuration of FIGS. 2A-2E may aid in such parallel placement of wires. In the configuration of FIG. 4C, for example, such parallel placement of the guide wires may be achieved beforehand (e.g., the Twin Pass Dual Access Catheter model 5200 by Vascular Solutions Inc.).
[0060] FIGS. 2B-E illustrates alternative embodiments of a dual-lumen balloon catheter. Particularly, FIG. 2B shows side guide wire lumen 241 with end 261 located at distal edge 272 of proximal tapered portion 210 of catheter 200B. In some cases, the embodiment of FIG. 2B may be used, for example to deliver a stent distal to the carina of a bifurcated vessel (as shown in FIGS. 4D and 4E). In this instance, the wire exiting lumen 261 will locate the carina accurately and the stent will be deployed accurately at the carinal and distal to it (FIG. 4E).
[0061] FIG. 2C shows side guide wire lumen 242 with first exit 262 located at or near distal edge 272 of proximal tapered portion 210 (i.e., a “first tapered edge”) and end 260 located at or near proximal edge 270 of distal tapered portion 220 (i.e., a “second tapered edge”) of catheter 200C. As such, the embodiment of FIG. 2C is a “universal” balloon catheter with the capability to accurately deliver a stent located proximal or distal to the carina.
[0062] FIG. 2D shows an alternative configuration of side guide wire lumen 243 with end 263 located at proximal edge 270 of distal tapered portion 220, but running alongside main guide wire lumen 230 for a least a portion of the length of balloon catheter 200D.
[0063] FIG. 2E shows yet another alternative configuration of a universal balloon catheter 200E with two wire lumens; lumen 240 terminating at opening 260 at edge 270 and lumen 244 terminating at opening 264 at edge 272.
[0064] Referring to FIG. 3, a cross-sectional view of balloon catheter 200A of FIG. 2A is depicted. In this embodiment, lumen 230 is usually located approximately at the center of catheter 200A, and lumen 240 is located outside the perimeter of catheter 200A. In alternative embodiments, lumen 240 may also be located along the perimeter but within balloon catheter 200A. Again, end 260 of lumen 240 may be located at or near shoulder region 270 of catheter 200A, near a point where catheter 200 begins to taper off (i.e., proximal edge 270 of distal shoulder region 220).
[0065] In various embodiments, radius 300 of catheter 200A may be designed so as to determine an angle or degree of tapering of distal end 220 and to facilitate insertion of catheter 200A in vessels of varying sizes. For example, a small radius 300 may reduce the profile of catheter 200A. Conversely, a large radius 300 may allow bifurcations with large angles and/or diameters to be properly treated using catheter 200A. In a number of applications, the distal balloon end may taper from the shoulder onwards as rapidly as technically feasible. Moreover, in some cases, a set of two or more catheters 200A with different diameters may be available, and a user or operator may select a suitable one among the set based on a location within the patient's body where a stent procedure will be performed (e.g., coronary arteries may require low profile, etc.).
[0066] It should be noted that, except in FIGS. 6, 7, 16A-C and 17A (where the stent balloon diagram represents an unexpanded balloon with the stent crimped on it), all other balloon diagrams (FIGS. 2A-E, 3, and 4A-G) are shown with the balloon expanded somewhat, but this is entirely for illustrative purposes. FIG. 4H is a self-expanding stent and does not require a balloon for deployment. Generally speaking, balloon lumen 281 (FIG. 2A) is collapsed when the stent is crimped on the balloon (i.e., the balloon is folded in an unexpanded state under the crimped stent). FIGS. 4E, 8-11, 12A, 17B, 18C, 19B, 20B, 21B and 22B may represent expanded versions of the stent-balloon configuration in some situations.
[0067] FIG. 4A is a diagram of bifurcation stent delivery device 400A according to some embodiments. As illustrated, device 400A utilizes the balloon catheter 200A depicted in FIG. 2A. Specifically, stent 440 may be positioned on the outer surface of balloon catheter 200A. In some cases, a distal edge of stent 440 may be aligned with edge 270 of shoulder region 220 on catheter 200A. Main guide wire 410 may be positioned in a vessel in a location desired by the operator or surgeon. Note that in most instances, wire 410 may be placed in the vessel across the lesion in the main branch 110 (shown in FIG. 1) and further across the first side branch 120-A (shown in FIG. 1), which is chosen because it is the more difficult lesion to cross. Wire 420 may be placed across the other side branch 120B (shown in FIG. 1) beforehand or after the stent approaches the carinal bifurcation point 130 (shown in FIG. 1).
[0068] Main guide wire 410 is inserted through main lumen 230 of catheter 200A into end 250 and out of proximal end 201 (shown in FIG. 2). Catheter 200A is then advanced along guide wire 410 into the vessel and positioned as desired. Similarly, side guide wire 420 may be inserted through side lumen 240 of catheter 200A into end 260 and out end 202 (also shown in FIG. 2). In other embodiments, as shown in FIGS. 2B and 2C, lumen 240 may terminate at the distal shoulder 272 of tapered region 210, where side guide wire 420 may exit through end 261 or exit 262 (shown in FIGS. 2B and 2C). Alternatively, the side guide wire 420 may be introduced through the proximal end 202 into lumen 240 to exit from the end 260, 261 or 262 as the case may be, after the catheter 200A has already been advanced into the artery close to the carina.
[0069] FIG. 4B shows an alternative configuration for bifurcation stent delivery device 400B according to some embodiments. Specifically, device 400B employs balloon catheter 200D shown in FIG. 2D.
[0070] FIG. 4C shows stent delivery device 400C where the second side guide wire channel 244 is approximately the same length as the cylindrical portion of the balloon and slightly longer than the stent 440 spanning from shoulder 272 to shoulder 270. In this configuration, both wires 410 and 420 may be placed across the main branch and side branches 120A and 120B (shown in FIG. 1) before threading the guide wires into the stent delivery device 400C. Wires 410 and 420 may be of approximately the same lengths allowing for one catheter to be exchanged for another.
[0071] FIG. 4D illustrates a bifurcation stent delivery device 400D using balloon catheter 200B of FIG. 2B. In this embodiment, as previously shown, side guide wire 420 may leave side guide wire lumen 240 through end 261. As such, this device configuration may be particularly well suited for accurately placing stent 440 at the carina beyond the main branch and into one of the side branches 120A or 120B (shown in FIG. 1).
[0072] FIG. 4E shows device 400D positioned within side branch 120A beyond carina 130. As device 400D is insertion into side branch 120A, guide wire 420 causes device 400D to stop at carina 130 with stent 440 accurately located at carina 130 and extending into branch 120A. In some cases, such a technique may be used, for example, to preserve side branches and/or to prevent jailing of the side branch—i.e., prevent the stent from deployed in such a way as to block or partially block access to the side branch Besides accurate positioning of the stent beyond the carina, the added advantage of this technique is that the wire 420 maintains access to the side branch 120B in case side branch 120B needs intervention should the carina shift laterally and obstruct blood flow to the side branch 120B.
[0073] FIG. 4F shows bifurcation stent delivery device 400F employing balloon catheter 200C of FIG. 2C. Particularly, balloon 200C may have two exit points (260 and 262) in lumen 242 for guide wire 420. For example, wire 420 may leave catheter 200C through exit 260 (at or near edge 270 of distal tapered region 220) for placement of stent 440 at the carina of a bifurcation and just before a side branch. Proximal exit point 262 (at or near edge 272 of proximal tapered region 210) may be used to place stent 440 accurately after the carina and within a side branch.
[0074] FIG. 4G shows device 400G with a balloon catheter with three lumens—center lumen 230 and side lumens 240 and 245. Each lumen is configured to hold a different guide wire 410, 420, 430. As such, device 400G may be particularly well suited for a procedure involving a trifurcation or the like (e.g., where a vessel includes a main branch splitting into three side branches). In this case, each of guide wires 410, 420, 430 may facilitate positioning a stent with respect to each of three side branches.
[0075] FIG. 4H shows bifurcation delivery device 400H in a configuration suitable for use with self-expanding stents. Particularly, device 400H includes outer sheath 450, self-expanding stent 440, and inner shaft 460, as well as main lumen 230 and side channel 246. Delivery of stent 440 may be accomplished by unsheathing stent 440, for example, by pulling back outer sheath 450. In the experience of the inventor hereof, the self-expanding stent should be oversized to the extent that it has to splay and closely conform to the spread of the bifurcation. Often the stent has to be partially released a millimeter or two before the carina and simultaneously gently advanced forward to get it to the carina and sometimes a fraction of the strut length beyond the carina. Thus, a method of deploying a self-expanding stent may be different from another method using a balloon expandable stent. Typically, self-expanding stents are intended for peripheral use. A bifurcation deployment may be considered, for example, the common Iliac bifurcation to the external and internal Iliac or the common femoral to superficial femoral and profound femoris bifurcation. The use of a second wire lumen 246, as described herein, may allow accurate placement of the stent at the bifurcation while allowing for luminal placement of both of the wires in each side branch vis-à-vis the stent in the main vessel.
[0076] FIG. 5 is a flowchart of a bifurcation stent delivery technique according to some embodiments. To further illustrate this technique, reference is also made to FIGS. 4A-G and 6-12. At block 505, a user or operator may position a stent (e.g., stent 440 in FIG. 4A) with its edge at or near a proximal edge (e.g., 270) of distal shoulder region (e.g., 220) of a balloon catheter (e.g., 200A). At block 510, the user may insert a first guide wire (e.g., main wire 410) in a first lumen, channel, or cavity (e.g., main lumen 230) of the catheter and/or may also insert a second guide wire (e.g., side wire 420) in a second lumen, channel, or cavity (e.g., side lumen 240) of the catheter. In other cases, however, a medical device manufacturer or the like may perform the operations indicated in blocks 505 and 510 to provide a pre-assembled bifurcation stent delivery device as shown in FIGS. 4A-G.
[0077] At block 515, the user may place the bifurcation stent delivery device in a patient's vessel using the first guide wire. For example, if the main guide wire is the “first guide wire,” it may be placed across the main vessel and into one of the branches. Typically, the first guide wire may be placed across the lesion in the main branch and the side branch that presents the more challenging stenosis to cross. This operation is shown in FIG. 6, as device 400A is introduced into main branch 110 toward the bifurcation into branches 120A and 120B. The second guide wire may be placed in the second branch (e.g. 120B) beforehand or as the stent approaches the bifurcation depending upon the configuration of the bifurcation stent delivery device. In some cases, a portion of side wire 420 leaving the device may be shaped at a first acute angle alpha (α) designed to (at least approximately) match a second acute angle beta (β) between side branches 120A and 120B, and therefore be inserted into side branch 120B. FIG. 6 also shows main wire 410 positioned inside one of the branches (e.g., branch 120A) of bifurcation 100 (for ease of illustration, stenotic plaques are not drawn). It will be understood that the main branch 110 and side branches 120A and 120B as drawn in the figures are merely examples for the purpose of illustration. The stents and methods described herein may be used with any sizes and any configuration of the main branch 110 and side branches 120A and 120B.
[0078] Returning to block 515, the user may advance device 400A until it stops at the carina of the bifurcation. This is illustrated in FIG. 7, where device 400A positions stent (e.g., 440) exactly at carina 130. In particular, FIG. 7 shows that side wire 420 may enter the other side vessels (e.g., 120B), and thus cause the insertion of device 400A to naturally stop at carina 130 (Carina Locator).
[0079] At block 520, the user may inflate the balloon catheter to deploy the stent while maintaining access to the first and second branches of the bifurcation via the first and second guide wires, respectively. FIG. 8 shows catheter 200A after it has been inflated so that expanded stent 440 is correctly positioned with respect to the bifurcation. FIG. 9 shows stent 440 expanded at carina 130 and straddling it after the catheter 200A has been deflated and removed. FIG. 9 also shows that side guide wire 420 has been positioned deeper within side branch 120B after deflation of catheter 200A. This may be achieved by advancing wire 420 into the side branch 120B simultaneously as the balloon deflates. Subsequently, the balloon catheter may be removed in a manner so that both guide wires (410 and 420) remain in place in each respective side branch. Importantly, it should be noted that both wires (410 and 420) are within the lumen of the stent.
[0080] At block 525, the user may apply a first kissing balloon procedure to splay the deployed stent 440 and to cause it to more fully conform to the walls of the bifurcation between the first and second side branches. FIG. 10 shows balloons 1000 and 1010, which have been advanced along their respective guide wires 420 and 410 through expanded stent 440 and into the side branches. The balloons 1000 and 1010 are inflated, thereby causing stent 440 to further expand and conform to the shape of the vessel at the bifurcation. After inflation of balloons 1000 and 1010, stent 440 is splayed across the bifurcation at carina 130. FIG. 11 is a diagram illustrating stent 440 fully splayed across carina 130 as a result of the first kissing balloon procedure after the balloons have been deflated and removed.
[0081] Returning to FIG. 5, at block 530 the user may apply a second kissing balloon procedure to deploy kissing stents within each branch of the bifurcation. The second kissing stent procedure is illustrated in FIGS. 12A and 12B. FIG. 12A shows balloon 1201 with stent 1202 and balloon 1203 with stent 1204. Balloons 1201 and 1203 have been advanced along the guide wires 410 and 420, respectively, through expanded stent 440 and into the side branches. Balloon 1201 and first kissing stent 1202 are positioned within first branch 120A and then balloon 1201 is inflated to expand stent 1202. Balloon 1203 and second kissing stent 1204 are positioned within second branch 120B and then balloon 1203 is inflated to expand stent 1204. Both stents being expanded by simultaneous balloon inflations.
[0082] FIG. 12B depicts the result of the second kissing balloon procedure with the deploying devices 1201 and 1203 removed from the vessel. As shown in FIGS. 12A and 12B, there may be an area of overlap between or among stents 440, 1202, and 1204 during inflation and after the balloons have been withdrawn. Unlike conventional or traditional bifurcation stenting methods, the methods described herein may ensure that the deployed stents are positioned accurately at the carina and cover the entire bifurcation uniformly. Depending upon the type of stent used, this may allow anti-restenosis drugs to be uniformly delivered to the bifurcation. Additionally, it is also to be noted that the methods described herein may ensure that all stent struts are opposed to the walls of the bifurcation, thus minimizing or otherwise reducing the chance of stent thrombosis.
[0083] Therefore, using the techniques outlined above, stents 1202 and 1204 may be positioned at the carina 130. These stents may be the regular pre-mounted stents, and in most cases, may not need to be reconfigured in any way. The stents used in the second kissing procedure may be deployed at the same time or sequentially. The configuration shown in FIG. 4E may be used to deploy stents 1202 and 1204 accurately at the carina 130 and beyond. For example, a first stent delivery device may enter the vessel with lumen 230 on the wire 410 and with side branch wire 420 going through lumen 241. This would be used to deploy stent 1202. A second stent delivery device may then enter the vessel with lumen 230 on wire 420 and with side branch wire 410 going through lumen 241. This would be used to deploy stent 1204.
[0084] After stents 1202 and 1204 have been deployed, another kissing balloon inflation across the bifurcation (e.g. FIG. 10) may be employed to complete the procedure and cause optimal or otherwise improved expansion and opposition of the stents to the wall of the vessel. This particular stent deployment technique at the carina may save on the amount of radiation and/or contrast usage, and it may improve patients' outcomes due to its ability to position stents accurately at the carina.
Alternatives to Multi-Lumen Balloon Catheters
[0085] In some situations, a pre-configured or pre-manufactured dual-lumen balloon catheter may not be readily available to a user. However, one or more of the stent deployment methods described herein may be used with single-lumen, conventional catheters. This is the second group or type of devices referred to above. For example, a dual-guide wire stent may be constructed from a single-lumen catheter stent by adding a second guide wire between the stent and the balloon. The stent may be removed from the balloon and the second guide-wire positioned inside the stent. The stent may then be reinstalled on the balloon.
[0086] Starting with a single-lumen catheter, a stent delivery device may be assembled in different ways depending upon the type of stent being used (i.e., a closed-cell stent versus an open-cell stent). For example, the operation of removing the stent from its balloon catheter may be performed differently open-cell versus closed cell stents, so as to maintain the integrity of the stent. Typically, open-cell stents cannot be properly crimped back onto the balloon once expanded because non-linked struts tend to not fold back well. In contrast, a closed-cell can usually be crimped back after being expanded. For example, if Medtronic Inc.'s ENDEAVOR® or RESOLUTE INTEGRITY® open-cell stents are used, the stent may be taken off the balloon without inflating the balloon catheter. Alternatively, a closed-cell stent such as Cordis Corporation's CYPHER® stent may be taken off the balloon by first inflating the balloon and then expanding the stent.
[0087] The dual balloon and other configurations of open-celled stents as described herein may be pre-manufactured. This would ensure that the open cell stents are not damaged by manual handling of the stents.
[0088] This stent configuration (i.e., a balloon catheter, a stent, and a second guide-wire positioned between the balloon and the stent) may be constructed by the operator or may be pre-built by a manufacturer. An advantage of this configuration is that its cross-section profile may be the lowest, especially if the device is pre-built by the manufacturer, due to the missing side lumen. However, the same configuration may require above-average operator skill to maneuver the second wire trapped under the stent into the side branch. Specifically, the entire balloon-stent-second-wire device may have to be maneuvered into the main branch and turned so that the second wire enters the second side branch. In some cases, to alleviate these concerns, a spring-coiled tip wire (e.g., Boston Scientific Corp.'s CHOICE® Floppy Guide Wire) may be used as the second wire under the stent and the tip may be steered into the second side branch, even though the spring coil is under the stent, because the distal wire tip is connected to the steel core of the wire under the spring coils.
[0089] Again, in the case of the off-label use of a closed-cell stent, for example, a traditional stent balloon (e.g., the CYPHER® stent) may be inflated outside the body and the stent expanded. A secondary wire (e.g., a 0.014 spring tip wire because the internal stent wire is attached to the tip and can rotate the tip even if the wire is under the crimped stent) may be introduced between the balloon and the stent struts. The stent may be re-crimped to trap the secondary wire between the stent and the balloon. In some applications, an approximately ˜3-5 mm tip of the wire may be kept curved beyond the stent. Additionally, a 0.014 guide wire may be introduced to the main (or only) lumen to prevent damage to this channel when re-crimping the stent. As described above, the stent may be positioned forward onto the distal shoulder of the balloon, usually at the distal edge of the distal balloon marker on the shaft. The stent may be then re-crimped (e.g., manually by the operator's fingers), and a #2.0 silk or the like may be wrapped around the stent and further crimped manually. A 6F sheath may also be cut into approximately ˜1.5-2.5 inches, split, and placed on the shaft of the balloon with the second wire in it. The proximal side of this piece of the sheath may be beveled and used to introduce the stent through the valve of a Touhy Borst adapter or another medical apparatus used for attaching catheters to other devices. The stent may be loaded on the wire that is main branch of the bifurcation. As the stent is advanced, the secondary wire may be manipulated so that it enters the side branch of the bifurcation. Again, the stent may advance until the side branch wire locates the carina and stops naturally at the carina. After the stent is deployed at the carina and the balloon is being deflated, the side branch wire may be advanced into the side branch, and the process may continue similarly as otherwise described herein.
[0090] In the case of the off-label use of an open-cell stent, an operator may receive an assembled device including a balloon catheter and the open-cell stent. As before, the balloon catheter may be a single-lumen catheter—i.e., configured to accept only one guide wire. However, rather than inflating the balloon to expand the stent, the operator may slide the stent off of the balloon to remove it from the assembly. The stent may be loosened off the balloon by rocking the proximal and distal portions of the balloon shaft within the stent in multiple directions. This expands the stent minimally to get it off the balloon. For example, in some cases an approximately ˜8-9 mm stent may be used for this purpose. Then, a second guide wire may be added between an inner surface of the stent and an outer surface of the balloon catheter, and the stent may be slid back over the catheter, thus trapping the second guide wire between the stent and the catheter. The distal edge of the stent in the assembled device may be at the distal shoulder region of the balloon. The stent may be re-crimped manually, for example, with a #2 silk thread similarly as described for the closed-cell stent above.
[0091] In some situations, when there is a stent with a second wire under the stent, either assembled at the time of the case with available materials (as described above) or pre-manufactured as described herein, an introducer device may be used to get the stent-wire configuration across a hemostasis valve without damaging or changing the shape of the second guide wire tip protruding from the distal edge of the stent. Such an introducer may be manufactured in vitro, for example, by cutting an appropriate length of a #6 French sheath as described above.
[0092] FIG. 13A illustrates open-cell stent 1305 that may be used to assemble a bifurcation delivery device following the operations described in connection with FIG. 14. Particularly, open-cell stent 1305 with a crown of struts 1330 may have one or more struts unattached to the adjacent crown of struts, thus creating a few struts 1310 that are interconnected. In this case, cells 1340 are considered to be open—although, typically, one of every 3-6 cells may be connected to each other.
[0093] FIG. 13B shows closed-cell stent 1315, which may be used following the operations described in FIG. 15. In contrast with open-cell stent 1305, every crown of struts 1335 of closed-cell stent 1315 is connected to the adjacent crown of struts 1335, thus creating all closed cells 1320.
[0094] FIG. 13C shows an example of a bifurcation stent delivery device employing a single-lumen catheter, as described above. Device 1300 is similar to device 400C shown in FIG. 4C, but without second lumen 244. In device 1300, side guide wire 1301 is positioned between stent 1302 and catheter 1303. Although stent 1302 is illustrated as a closed-cell stent (e.g., as in FIG. 13B), an open-cell stent may also be used (e.g., as in FIG. 13A). In situations where the device is assembled by an operator in an “off-label” procedure (i.e., as opposed to pre-built by a manufacturer), the methods depicted in FIGS. 14 and 15 may be employed. Main guide wire 1304 is positioned in the vessel across the bifurcation and into a first branch. Device 1300 may be advanced along main guide wire 1304 into the vessel toward the bifurcation. Side guide wire section 1301A will be guided into the second branch as device 1300 approaches the bifurcation. Wire section 1301A may be curved to assist in “catching” the second branch. This will stop the balloon 1303 and stent 1302 adjacent to the carina of the bifurcation by physically locating the carina. The stent may then be deployed and subsequently splayed across the bifurcation as described above.
[0095] Turning now to FIG. 14, a flowchart of a bifurcation stent delivery device assembly using a single-lumen catheter with a closed-cell stent (e.g., in FIG. 13B) is depicted according to some embodiments. At block 1405, the user may inflate the balloon to expand the stent outside the patient's body. At block 1410, a user may position a stent at a forward shoulder of a balloon catheter having a single lumen. Positioning the stent at the forward shoulder of the lumen will help to deploy the stent right at the carina of the bifurcation. At block 1415, the user may insert a secondary wire between the balloon and the stent. Then, at block 1420, the user may re-crimp the stent to trap the secondary wire between the stent and the balloon while leaving a curved portion beyond the stent. The curved portion will be directed into a side branch at the bifurcation to help position the stent at the carina.
[0096] The technique shown in FIG. 14 is particularly suitable for use with closed-cell stents, where the stent is amenable to being expanded and re-crimped, thus returning to its original configuration. As the inventor hereof has recognized, in the case of open-cell stents, it may not be possible to return the stent to its original form after its initial expansion. Nonetheless, it has been determined that, with respect to pre-assembled stent delivery devices having an open-cell stent surrounding a balloon catheter, the open-cell stent in certain types of stents, may be removed from the assembly without causing damage to the stent or to the catheter without inflating the stent.
[0097] Accordingly, FIG. 15 is a flowchart of a bifurcation stent delivery device assembly using a single-lumen catheter with an open-cell stent according to some embodiments. At block 1505, the user or operator may receive the pre-assembled delivery device and may slide the open-cell stent off of the catheter to remove it from the assembly. In some cases, this operation may require that the user apply some amount of manipulation to loosen the stent and use some amount of gentle force to get the stent off the balloon. At block 1510, the operator may insert a secondary guide wire between the balloon and the stent. Then, at block 1515, the user may slide the stent back over the balloon catheter, thus trapping the secondary guide wire between the stent and the balloon while positioning the distal edge of the stent at the tapered edge of the balloon, typically farther forward that its original position in the assembly.
[0098] In some cases, the pre-assembled device may be such that the edge of the open-cell stent is positioned at the distal shoulder region of the catheter (e.g., very close to, or exactly on the tapered edge). In many applications, such repositioning of the open-cell stent may ensure that the second guide wire, now trapped between the stent and the balloon catheter, will cause a) the stent to stop at the carina of the bifurcation and b) the stent to be deployed accurately at the carina of a bifurcation during balloon expansion.
[0099] FIGS. 16A-C are diagrams of alternative delivery devices according to some embodiments. Particularly, FIG. 16A shows a dual balloon configuration 1600 with single stent 1601 crimped over two balloons 1602 and 1603. Radiopaque markers on the shaft or the stent may be used to help position the stent at the carina. In some implementations, a commercially available stent-balloon catheter may be modified by crimping stent 1601 over two parallel balloon catheters 1602 and 1603. Balloons 1602 and 1603 are sized to fit into the first and second side branches of a bifurcation. Two parallel guide wires 1605 and 1606 are first placed in the vessel and each guide wire is positioned into its own side branch of the bifurcation. Each balloon 1602, 1603 is then advanced along the guide wires 1605 and 1606 though the vessel to the bifurcation. The two balloon-stent device 1600 may stop at the carina and the stent then may be deployed at this location by inflating both the balloons at the same time. In such an embodiment, the deployment and splaying of the distal portion of the stent may occur at the same time as pre-dilatation of the stenosis in the first and second side branches. If only open-cell stents are available on the market, this dual balloon configuration may be pre-manufactured. The configuration may be used with the closed-cell Cypher stent, but this stent is currently off the market and no longer available from the manufacturer.
[0100] FIG. 16B depicts stent delivery device 1610 according to an alternative embodiment. Specifically, stent 1611 is crimped over a parallel combination of balloon catheter 1612 (for a first guide wire) and a long tube catheter 1613 with an approximately 0.014-inch wire lumen (for a second guide wire). Device 1610 may also include markers (not shown) on the shaft of the stent itself to assist in positioning the device. The embodiment of device 1610 with catheter 1613 may facilitate accurate delivery at the carina while maintaining dual side branch access through the stent lumen.
[0101] FIG. 16C depicts another embodiment of a stent delivery device. Stent 1621 is crimped over balloon catheters 1622 and 1623. The catheters have inflation balloon sections that are longer than stent 1621. As a result, sections 1625 on each balloon 1622, 1623 extend beyond the distal edge of stent 1621. This configuration may be useful, for example, to dilate each side branch 120A and 120B (FIG. 10) of the bifurcation when stent 1621 is deployed. This would prepare the side branches for a subsequent kissing stenting operation. Additionally, the inflation of segments 1625 in different side branches would cause stent 1621 to be splayed across the bifurcation with the first inflation itself. This embodiment may make it easier to splay stent 1621 in order to achieve the configuration depicted in of FIG. 10 and FIG. 11, for example.
[0102] FIG. 17A illustrates a three-stent delivery device 1700 according to another alternative embodiment. A stent 1704 is positioned on balloon 1702 and stent 1705 is positioned on balloon 1703. Thereafter stent 1701 is positioned around both the balloon catheters 1702 and 1703, with the distal end of the stent overlapping the stents 1704 and 1705. This configuration allows for the simultaneous deployment of stent 1701 in the main vessel before a bifurcation and deployment of stents 1704 and 1705 in separate side branches.
[0103] FIG. 17B illustrates device 1700 deployed at a bifurcation. First, guide wires 1706, 1707 are positioned though main branch 110 and into separate side branches 120A, 120B. Then, device 1700 is advanced along the guide wires with balloon catheter 1702 traveling along guide wire 1706 and balloon catheter 1703 traveling along guide wire 1707. As device 1700 approaches the bifurcation, the balloons are directed into separate side branches. The device will stop moving into the vessel when the balloon segments covered by stents 1704 and 1705 have entered the side branches. Stent 1701 cannot move into the side branches, but will be stopped at carina 130. Once the device 1700 is positioned with stent 1701 at the carina in this manner, the balloons 1702, 1703 may be inflated as illustrated in FIG. 17B. This inflation will simultaneously deploy stent 1701 in the main vessel proximal to carina 130 and stents 1704, 1705 in the side branches distal to carina 130. Additionally, device 1700 performs the kissing balloon techniques when it is inflated, which splays stent 1701 across the bifurcation.
[0104] Existing methods for stenting in the location of a bifurcation are directed to stenting the main branch of a vessel and then positioning a stent in the side branch. In one existing technique for deployment, a single stent is crimped onto two balloons. A main branch balloon extends the length of the stent. A side-branch balloon that is mounted on an over-the-wire (OTW) lumen exits the stent at the mid-point. A single, common inflation lumen may be used to pressurize the balloons with a single-inflation device. The system is advanced to a point just proximal to the target bifurcation. A wire is then introduced into the OTW lumen to exit the side branch balloon tip and placed in the side-branch vessel. The system is then advanced into the bifurcation until forward motion stops. With a single inflation device, both the main and side branch balloons are pressurized, deploying the stent in the main branch and opening a portal into the side branch. A second balloon is then advanced along the side-branch wire to deploy a second stent in the side-branch. The existing methods require the deployment of multiple stents at the bifurcation, which requires additional time and introduces additional risk of misplacement or other errors. The individual stents used in existing multi-stenting procedures are not physically connected, which means that placement varies with each patient and relative uniformly and reproducibly accurate placement of the stents cannot be ensured.
[0105] FIG. 18A illustrates a bifurcation-stent delivery device 1800. Bifurcation stent 1802 includes a main portion 1804, a first side-branch portion 1806, and a second side-branch portion 1808. The stent portions 1804, 1806, and 1808 may be separate stent devices that are mechanically coupled together, such as by welding separate stents together. Alternatively, stent portions 1804, 1806, and 1808 of bifurcation stent 1802 may be integrally linked together, such as being formed from continuous wires that form the main portion 1804 and side-branch portions 1806 and 1808. Any other appropriate mechanism or method of manufacture may also be used to create the bifurcation stent 1802.
[0106] As shown in FIG. 18A and in the cross-sectional view in FIG. 18B, the proximal end of first side-branch portion 1806 is mechanically coupled to the distal end of main portion 1804 by one or more first exterior welds 1810. Similarly, the proximal end of second side branch stent portion 1808 is mechanically coupled to the distal end of main portion 1804 by one or more second exterior welds 1812. Any number of exterior welds 1810 and/or 1812 may be implemented to mechanically couple the side-branch portions 1806 and 1808 to the main portion 1804. In one embodiment, the exterior welds 1810, 1812 may be spread across an arc 1814, 1816 of approximately 90 degrees or less along the proximal end of side-branch portions 1806 and 1808. The region or arcs 1814, 1816 in which the welds are located may correspond generally to the areas in which the proximal end of side-branch portions 1806 and 1808 and the distal end of main portion 1804 meet as shown in the cross-section view FIG. 18B. One or more branch welds 1818 may be used to mechanically couple the proximal ends of side-branch portions 1806 and 1808 together in the region of the distal end of main portion 1804.
[0107] The portions of the distal end of main portion 1804 outside welded regions 1814 and 1816 may not be mechanically coupled to the proximal ends of side-branch portions 1806 and 1808. For example, the stent wires in areas 1819 in FIG. 18A are not mechanically coupled, which allows the individual sections (1804, 1806, 1808) of the bifurcation stent 1802 to conform to the respective main and side branches of the vessel upon deployment. This configuration provides a device that gives the side branch stents the ability to be conform to various angles of side branch anatomy.
[0108] Other embodiments contemplate other configurations and/or mechanisms for forming a single bifurcation-stent. For example, in FIGS. 18A and 19A, one or more wires may be used to form the main stent portion 1804, such as by coiling the wires. Some of the wires used to create bifurcation stent 1802 may be continuous through the main portion 1804 and first side-branch portion 1806 while others of the wires may be continuous through the main portion 1804 and second side-branch portion 1808. In such an example, the first side branch stent portion 1806 may be integrally formed with the main stent portion 1804, and the second side branch stent portion 1808 may be integrally formed with the main stent portion 1804. Hence, in such a stent, exterior welds 1810 and 1812 may be omitted. Further, the side branch stent portions 1806 and 1808 may be mechanically coupled together proximate the distal end of main stent portion 1804 using one or more welds 1818 or using additional wires integrally formed in both side-branch portions 1806 and 1808 instead of welds 1818.
[0109] Bifurcation stent 1802 is positioned on a first balloon 1820 and a second balloon 1822. The main portion 1804 is positioned on and around both the first and second balloons 1820 and 1822. The first side-branch portion 1806 is positioned on and around the first balloon 1820 only, and the second side-branch portion 1808 is positioned on and around the second balloon 1822 only. This configuration allows for the simultaneous deployment of main portion 1804 in a main vessel and side-branch portions 1806 and 1808 deployed in separate side branches with the distal end of the main portion abutting the carina of the bifurcation.
[0110] FIG. 18C illustrates device 1800 deployed at a bifurcation. First, guide wires 1824, 1826 are positioned though main branch 110 and into separate side branches 120A, 120B. Then, device 1800 is advanced along the guide wires 1820, 1822 with balloon catheter 1820 traveling along guide wire 1824 and balloon catheter 1822 traveling along guide wire 1826. As device 1800 approaches the bifurcation, the balloons are directed into separate side branches 120A,B. The device 1800 will stop moving into the vessel when the branch weld 1818 (or other attachment between the side-branch portions 1806, 1808) locates and abuts the carina 130. At that point, the balloon segments covered by the side branch stent portions 1806 and 1808 have entered the side branches 120B and 120A. The main stent portion 1804 cannot move into the side branches, but will be stopped at carina 130. Once the device 1800 is positioned with branch weld 1818 at the carina 130 in this manner, the balloons 1820, 1822 may be inflated as illustrated in FIG. 18C. This inflation will deploy bifurcation-stent 1802 with the main stent portion 1804 in the main vessel proximal to carina 130 and side branch stent portions 1806, 1808 in the side branches distal to carina 130. Additionally, device 1800 performs the kissing balloon techniques when it is inflated, which splays the main stent portion 1804 across the bifurcation.
[0111] FIG. 19A illustrates a single bifurcation-stent delivery device 1900 according to an alternative embodiment in which stent 1800 (FIG. 18A) is deployed using a Y-shaped balloon. The balloon 1901 has a main section 1902 adapted for main-branch portion 1804 of the stent 1802 and two branch sections 1904, 1906 adapted for side-branch portions 1806, 1808. Balloon 1901 has two lumens 1908 and 1910 that are adapted to ride on guidewires 1912, 1914 that are deployed in separate branches of a bifurcation. The balloon sections 1902, 1904, 1906 are inflated simultaneously through shaft 1916.
[0112] FIG. 19B illustrates device 1900 being deployed at a bifurcation.
[0113] FIG. 20A illustrates a single V-shaped bifurcation-stent delivery device 2000 according to an alternative embodiment. Stent 2002 is a V-shaped stent having a first side-branch portion 2004 and a second side-branch portion 2006. The two side-branch portions 2004, 2006 are adapted for deployment in separate branches beyond the carina of a bifurcation. The stent portions 2004, 2006 may be separate stent devices that are mechanically coupled together, such as by one or more welds 2008 that hold the separate stents together. Alternatively, stent portions 2004, 2006 of bifurcation stent 2002 may be integrally linked together, such as being formed from continuous wires that form the side-branch portions 2004 and 2006. In the continuous wire embodiment, point 2008 may be a bend or turn in the wire instead of a weld. Any other appropriate mechanism or method of manufacture may also be used to create the bifurcation stent 2002.
[0114] In FIG. 20A, Bifurcation stent 2002 is positioned on a first balloon 2010 and a second balloon 2012. The first side-branch portion 2004 is positioned on and around the first balloon 2010 only, and the second side-branch portion 2006 is positioned on and around the second balloon 2012 only. This configuration allows for the simultaneous deployment of the side-branch portions 2004 and 2006 in separate side branches with the proximal end stent abutting the carina of the bifurcation at weld point 2008.
[0115] FIG. 20B illustrates device 2000 being deployed at a bifurcation using guide wires 2014 and 2016.
[0116] FIG. 21A illustrates a single bifurcation-stent delivery device 2100 according to an alternative embodiment in which stent 2002 (FIG. 20A) is deployed using a Y-shaped balloon. The balloon 2101 has a main section 2102 and two branch sections 2104, 2106 that are adapted for side-branch stent portions 2004, 2006, respectively. Balloon 2101 has two lumens 2108 and 2110 that are adapted to ride on guidewires 2112, 2114 that are deployed in separate branches of a bifurcation. The balloon sections 2102, 2104, 2106 are inflated simultaneously by injecting liquid through shaft 2116.
[0117] FIG. 21B illustrates device 2100 being deployed at a bifurcation using guide wires 2112 and 2114. One advantage to having balloon section 2102 inflate—even though section 2102 is not deploying a stent—is to further hold device 2100 in position during stent 2002 deployment. Additionally, inflation of section 2102 may provide balloon angioplasty to the area in the main vessel proximal to the carina 130.
[0118] FIG. 22A illustrates a single bifurcation-stent delivery device 2200 according to an alternative embodiment in which stent 2002 (FIG. 20A) is deployed using a V-shaped balloon having little or no expansion in the main branch. The balloon 2201 has two branch sections 2202 and 2204 that are adapted for side-branch stent portions 2004, 2006, respectively. The two branch sections 2202 and 2204 are joined to shaft 2216 in balloon area 2206. Balloon 2201 has two lumens 2208 and 2210 that are adapted to ride on guidewires 2212, 2214, which are deployed in separate branches of a bifurcation. The balloon sections 2202 and 2204 are inflated simultaneously by injecting liquid through shaft 2216.
[0119] FIG. 22B illustrates device 2200 being deployed at a bifurcation using guide wires 2212 and 2214. Balloon sections 2202 and 2204 inflate to deploy side-branch stent portions 2004, 2006. Balloon area 2206 inflates minimally or not at all in main branch 110 when balloon sections 2202 and 2204 are inflated.
[0120] Although the bonds between different stent portions described above are disclosed in the examples of FIGS. 18-22, it will be understood that any bonding method or material may be used including, without limitation, welds, solder, glue, adhesive, epoxy, polymers, or the like. Alternatively, wires in two or more separate stent portions may be bound together using hardware such as bolts, pins, rivets, clamps, clips, ties, or other fasteners.
[0121] It will be understood that the stents may be manufactured using any appropriate material, such as Stainless Steel, Nickel Titanium (Nitinol), Titanium, Cobalt Chromium, or other metals or alloys. The stents may be bare metal or may be treated with a drug. Stents may also be coated with a pharmacologic agent, therapeutic agent, or drug (drug-eluting stents (DES) or medicated stents). Such drugs may have anti-inflammatory, antiproliferative, or other properties and may be used, for example, to suppress restenosis—the reblocking or closing of an artery after angioplasty due to excess tissue growth inside or at the edge of the stent. The drugs may be bonded directly to a metal stent or to a matrix polymer, which acts as a drug reservoir to ensure drug retention during deployment and uniform distribution on the stent.
[0122] In the example welded bifurcation-stents described above relating to FIGS. 18-22, it will be understood that the separate stent portions (i.e., main-branch and side-brand portions) of the single bifurcation-stent may be manufactured from different materials and then combined using welds or other attachment means. Additionally, the separate stent portions of the single bifurcation-stent may have different drug-eluting properties, such as different drugs coatings or bare metal on separate stent portions.
[0123] As a person of ordinary skill in the art will recognize in light of this disclosure, one or more of the numerous embodiments described herein may provide one or more advantages over known stent deployment techniques. For example, some of these embodiments may prevent guide wires from becoming tangled. In some cases, access to a side branch may be maintained using the second guide wire when deploying a stent in the main vessel. Furthermore, the wire going into the side branches may be maintained within the lumen of the stent, rather than through the stent struts. One or more of the techniques disclosed herein may also guarantee the exact location of the stent at the carina, which makes it less likely that areas of the bifurcation lesion will remain uncovered by stents after treatment.
[0124] Moreover, in contrast with existing devices currently used to treat bifurcation lesions, one or more of the devices disclosed herein may be manufactured with a low or small profile, may be easy to maneuver, and may therefore be particularly well suited for the treatment of coronary arteries, which are typically small in diameter (although it may also be used in any bifurcation lesion). In some devices, the side lumen may ensure access to the side branch of the bifurcation. Further, in some cases, the side guide wire may help place the main stent exactly at the carina. Because in embodiments where the bare wire is trapped under the stent the side guide wire is generally unable to move within the lumen, a ‘V’ shape may be created between the guide wire and the balloon catheter of the main branch stent. As the device advances with the side wire in the side branch and the main wire in the main branch, it may stop at the vertex of the bifurcation. As such, one or more of the techniques described herein may guarantee precise placement of a stent at the carina with any amount of plaque buildup in the arteries, and while ensuring there is full coverage of the bifurcation. Under fluoroscopy in two dimensions, it is often very difficult to identify the precise location of the carina in two dimensions because of variable side branch vessel overlap. Hence the particular suitability of certain of these techniques and innovations to accurately place stents at bifurcations in coronary, peripheral vascular, venous or other anatomical locations.
[0125] In some cases, the stent delivery systems and methods described herein may provide a 100% or near 100% apposition or coverage of the bifurcation lesion by the stent struts, thereby eliminating a limitation of present day stenting of such lesions. In a typical scenario, 100% coverage of the lesion may be a particularly critical issue with local lesion drug delivery by drug eluting stents to prevent restenosis. In addition, 100% or near 100% stent apposition to the bifurcation lesion ensures that luminal access to each branch is wide open—that is, stent struts do not protrude into the lumen and a true pantaloons configuration may be obtained. This method of stenting may therefore eliminate or otherwise reduce the risk of stent thrombosis caused by stent struts that are not opposed to the wall of the vessel. Furthermore, in the case of restenosis or new lesions developing downstream to the bifurcation, normal anatomical access allows subsequent operators to cross through the bifurcation with wires, balloons and stents without any metallic luminal obstacles caused by struts not in apposition to the walls of the bifurcation.
[0126] In some cases, the stent delivery systems and methods described herein may also prevent the carina of the bifurcation from being shifted from its anatomical location. This may be guaranteed by deflating the kissing balloons together at the same inflation pressures. The stent in the main vessel may be accurately delivered at the carina by making sure that the distal end of the stent is positioned forward on the shoulder or distal taper of the deploying balloon than is the case with more conventional stents. This prevents the stent from being pushed away from the carina by inflation of the balloon during inflation. In addition, problems of plaque shifting are also eliminated or otherwise reduced. In various implementations, the two wires in each lumen may always be within the lumen of the stents and do not at any time go through stent struts.
[0127] Certain conventional balloon and stent profiles are small enough to utilize certain of the stent delivery techniques described herein, for instance, through an 8F (crossing profile of the guiding catheter) system. For example, the closed-cell design of the CYPHER® stent is particularly suitable for this method because it can be re-crimped after expanding it outside the patient's body. Other open cell stents such as, for example, the ENDEAVOR®, or the RESOLUTE INTEGRITY® may be loosened and removed from the balloon without expanding the stent. Also, conventional stents, wires, and materials may be used to reconfigure a stent for delivery at the bifurcation (i.e., off-FDA label utilization of these stents). While such an off-label technique may require a higher level of operator expertise for reconfiguration of the stent for the bifurcation, after the initial learning curve is overcome, such a method is also very feasible.
[0128] With one or more of the innovations described herein, stent delivery systems can be created to make the delivery operator friendly and achieve routine use for bifurcation stenting. Additional innovations described herein may be used to accurately deliver a stent at a trifurcation, for example, a left-main trifurcation into the left anterior descending, ramus intermedius and circumflex arteries. Yet additional innovations may accurately deliver stents beyond the carina without jailing a side branch. This may be utilized in other non-bifurcation lesion situations where stenting is required in the main vessel but the stent needs to be delivered without jailing a side branch, while maintaining access to the branch in case the carina is shifted.
[0129] As such, in various embodiments, the stent delivery systems and methods described herein may be particularly useful for use with patients who cannot undergo bypass surgery safely. Moreover, one or more of these techniques may be safely used in patients with “complex” bifurcation lesions, thus making complex bifurcation operations a matter of routine; thus, helping decrease the need for such surgery.
[0130] The various systems and methods illustrated in the figures and described herein represent example embodiments of systems and methods for deploying stents within bifurcated blood vessels. The order in which each operation of a given method is performed may be changed, and various elements of the systems or devices illustrated herein may be added, reordered, combined, omitted, modified, etc. Various modifications and changes may be made as would be clear to a person of ordinary skill in the art having the benefit of this specification. It is intended that the invention(s) described herein embrace all such modifications and changes and, accordingly, the above description should be regarded in an illustrative rather than a restrictive sense.
