Intraluminal flexible stent device

A stent made up of at least two connected bands, each band having a pattern of undulations formed from long, short and mid-sized segments connected together by turns. In particular, the pattern includes a repeating series having five segments: a long segment, a short segment, a mid-sized segment, a mid-sized segment, a short segment (LSMMS). When adjacent bands are connected together to form the stent body, the LSMMS segment configuration forms a series of consecutive tapered gaps between the consecutive unconnected close ended turns of adjacent bands which provide greater flexibility for the stent. The series of consecutive tapered gaps allow the stent to flex with little or no interference with adjacent bands when the stent is tracked around a small radius bend in a vessel. In addition, the length of the longest rigid element of the stent is decreased to further improve flexibility. A rigid element is formed by the lengths of the segments on both sides of a connection between adjacent bands. By decreasing the length of this rigid element, the length which must be tracked around the bends of a vessel is shortened and thus the stent is easier to advance.

FIELD OF THE INVENTION

The present invention is directed to intraluminal stents for use in maintaining open collapsed lumen walls, the intraluminal stent having extreme flexibility for being tracked around bends of a vessel having small radii.

BACKGROUND OF THE INVENTION

A wide range of medical treatments have been previously developed using “endoluminal prostheses,” which terms are herein intended to mean medical devices which are adapted for temporary or permanent implantation within a body lumen, including both naturally occurring or artificially made lumens. Examples of lumens in which endoluminal prostheses may be implanted include, without limitation: arteries, such as those located within the coronary, mesentery, peripheral, or cerebral vasculature; veins; gastrointestinal tract; biliary tract; urethra; trachea; hepatic shunts; and fallopian tubes. Various types of endoluminal prostheses have also been developed, each providing a uniquely beneficial structure to modify the mechanics of the targeted luminal wall.

For example, stent prostheses have been previously disclosed for implantation within body lumens. Various stent designs have been previously disclosed for providing artificial radial support to the wall tissue, which forms the various lumens within the body, and often more specifically within the blood vessels of the body.

Cardiovascular disease, including atherosclerosis, is the leading cause of death in the U.S. The medical community has developed a number of methods and devices for treating coronary heart disease, some of which are specifically designed to treat the complications resulting from atherosclerosis and other forms of coronary arterial narrowing.

One method for treating atherosclerosis and other forms of coronary narrowing is percutaneous transluminal coronary angioplasty, commonly referred to as “angioplasty,” “PTA” or “PTCA”. The objective in angioplasty is to enlarge the lumen of the affected coronary artery by radial hydraulic expansion. The procedure is accomplished by inflating a balloon of a balloon catheter within the narrowed lumen of the coronary artery. In some instances the vessel restenoses chronically, or closes down acutely, negating the positive effects of the angioplasty procedure.

To provide radial support to the treated vessel in order to prolong the positive effects of PTCA, a stent may be implanted in conjunction with the procedure. Effectively, the stent overcomes the natural tendency of the vessel walls of some patients to close back down, thereby maintaining a more normal flow of blood through that vessel than would be possible if the stent were not in place. Under this procedure, the stent may be collapsed to an insertion diameter and inserted into a body lumen at a site remote from the diseased vessel. The stent may then be delivered to the desired site of treatment within the affected lumen and deployed to its desired diameter for treatment.

Access to a treatment site is most often reached from the femoral artery. A flexible guiding catheter is inserted through a sheath into the femoral artery. The guiding catheter is advanced through the femoral artery into the iliac artery and into the ascending aorta. Further advancement of the flexible catheter involves the negotiation of an approximately 180 degree turn through the aortic arch to allow the guiding catheter to descend into the aortic cusp where entry may be gained to either the left or the right coronary artery, as desired. Because the procedure requires insertion of the stent at a site remote from the site of treatment, the device must be guided through the potentially tortuous conduit of the body lumen to the treatment site. Therefore, the stent must be capable of being reduced to a small insertion diameter and must be flexible.

One stent configuration includes a plurality of wavelike bands having straight segments and turns (i.e., alternating turns facing opposite longitudinal directions). The bands are connected together to form an expandable tubular prosthesis. As the stent is tracked around bends of a vessel having small radii, the turns of adjacent bands may be forced together on the side of the stent adjacent to the inner side of the vessel bend. Often, the turns of adjacent bands on the inside of the vessel bend will interfere with each other or overlap. Such overlapping creates greater strains and an increased potential for permanent deformation of the stent segments in that immediate area.

Thus, it is desirable to have a flexible stent device which is designed so that interference between adjacent bands of the stent does not occur when the stent is tracked to the target location.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to an intraluminal stent device that solves many of the problems that occur when a stent is tracked through a potentially winding body conduit such as a blood vessel. In particular, stent bands of the present invention use a combination of short, mid-sized, and long segments to form a series of consecutive tapered gaps between unconnected closed-ended turns of adjacent bands when adjacent bands are connected together to form the stent body. The series of consecutive tapered gaps provide greater flexibility for the stent when the stent is tracked around a small radius bend in a vessel.

In one embodiment, the stent has generally undulating bands connected together. Each band has a pattern of undulations formed from long, short and mid-sized segments connected together by turns. The segments and turns form peaks and valleys of the stent, by which adjacent bands may be connected. In one particular embodiment, the pattern includes a repeating series of five segments and five turns which connect the segments together. The repeating series includes a long segment and a first short segment coupled by a first turn. The first short segment is coupled to a first mid-sized segment by a second turn. The first mid-sized segment is coupled to a second mid-sized segment by a third turn. The second mid-sized segment is coupled to a second short segment by a fourth turn, and the second short segment is coupled to the next series by a fifth turn. The order of the five segments has a LSMMS configuration (long, short, mid-sized, mid-sized, short). When adjacent bands are connected together to form the stent body, the LSMMS series having various segment lengths form a series of consecutive tapered gaps which provide greater flexibility for the stent. For example, the series of consecutive tapered gaps between the unconnected closed-ended turns of adjacent bands allow the stent to flex with little or no interference with adjacent bands when the stent is tracked around a small radius bend in a vessel.

The consecutive tapered nature of the series of gaps is advantageous in that the larger gaps optimally occur between turns of adjacent bands which generally experience the greatest amount of interference when the stent is tracked around a small radius bend in a vessel. Further, the smaller gaps also add to the stent body's flexibility while simultaneously providing greater scaffolding than that provided by the larger gaps. Greater scaffolding means that more area of the vessel walls is being supported directly by parts of the stent.

Another important aspect of the present invention includes minimizing the length of the longest rigid element of the stent to further improve flexibility. The longest rigid element of a stent body occurs at the location of a connection between adjacent bands. The lengths of the segments on both sides of the connection essentially form a rigid element which must be tracked around the bends of a vessel. By minimizing the length of this rigid element, the length which must be tracked around the bends of a vessel is shortened and thus the stent is easier to advance.

Adjacent bands may be formed from a toroid bent into the particular pattern. Thus, each band may be connected to an adjacent band by welding (or utilizing any appropriate type of mechanical connection) the turns to each other. Alternatively, the bands may be formed connected as a unitary structure.

The bands may be placed onto a balloon of a balloon catheter for expansion within a body lumen or they may naturally occur in an expanded condition and may be collapsed, reducing the overall profile for delivery. Once at the treatment site, the stent may be expanded to its natural condition.

DETAILED DESCRIPTION OF THE INVENTION

Specific embodiments of the present invention are now described with reference to the figures, wherein like reference numbers indicate identical or functionally similar elements. The drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number. The terms “distal” and “proximal” are used in the following description with respect to a position or direction relative to the treating clinician. “Distal” or “distally” are a position distant from or in a direction away from the clinician. “Proximal” and “proximally” are a position near or in a direction toward the clinician.

The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Although the description of the invention is in the context of treatment of blood vessels such as the coronary, carotid and renal arteries, the invention may also be used in any other body passageways where it is deemed useful. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

The present invention generally is directed to a stent made from generally circular single bands having a uniquely defined undulating shape. Bands are aligned on a common longitudinal axis to form a generally cylindrical body having a radial and longitudinal axis.FIG. 1shows a single band100of the present invention. Band100is shown in a schematic, as if the generally circular band100has been cut between ends102and104and the band100has been laid out flat, as if made from a ribbon bent into a sinusoidal shape. One skilled in the art can appreciate that a band100of the present invention may be manufactured in a variety of ways, which are discussed in further detail below. Thus, band100may be made flat, as shown inFIG. 1, rounded, elliptical, or have a variety of other cross-sections depending upon the desired features of the stent. Thus, a stent of the present invention is not limited to the ribbon structure shown inFIG. 1.

The generally cylindrical bands and stents are shown inFIGS. 2-8and10in a flattened state, such as the band100shown inFIG. 1. However, one skilled in the art can appreciate that the stents and bands100depicted therein are intended to be used in a cylindrical body.

When viewed flat, each band100is a wire having an undulating pattern. The pattern includes a repeating series106of segments and turns. In a first embodiment depicted inFIGS. 1-4, band100is formed from a closed toroid wire which is bent into the structure shown inFIG. 1. Thus, segments and turns are not necessarily coupled together at the ends, but are naturally continuing one into another. Other embodiments may be manufactured differently, such that some portions may be mechanically coupled together via welding, soldering, adhesive or another bonding or another mechanical connection method. However, to describe the particular structure of band100, various segments and turns may be described as being connected or coupled to each other. Thus, the terms “connect with,” “connected,” or “coupled” may mean either naturally continuing (or flowing together) or mechanically coupled together.

The repeating series106has five total segments, including a long segment108, a first short segment120, a first mid-sized segment132, a second mid-sized segment144, and a second short segment156. First and second short segments120,156are preferably the same length, while first and second mid-sized segments132,144are preferably the same length. Short segments120,156are shorter than mid-sized segments132,144and mid-sized segments132,144are shorter than long segment108. The order of the five segments of series106has a LSMMS configuration (long, short, mid-sized, mid-sized, short).

In addition, the series106has five total turns, including a first turn116, a second turn128, a third turn140, a fourth turn152, and a fifth turn164. The segments and turns form valleys and peaks of the stent, in which peaks face the opposite longitudinal direction than valleys. For the purpose of this description, peaks and valleys may face either longitudinal direction provided that all peaks face one longitudinal direction and all valleys face the opposite longitudinal direction. Thus, when two bands are side by side, flipping one band in the opposite direction would by definition convert all the peaks to valleys and valleys to peaks. For ease of description in this application, peaks are formed by turns to the right side of segments such that the closed end of the turn of a peak faces to the right and the open end of a peak faces to the left. Similarly, valleys are formed by turns to the left of segments such that the closed end of a turn of a valley faces left and the open end of a turn of a valley faces right. Thus, turns116,140, and164shown inFIG. 1are peaks and turns128and152shown inFIG. 1are valleys. The five turns116,128,140,152, and164connect the segments108,120,132,144, and156of the series106together, as described below.

Long segment108connects with the previous series106at a first end110. A second end112of long segment108connects with a first end114of a first turn116.

A second end118of first turn116connects with a first end122of a first short segment120. First short segment120is shorter than long segment108. A second end124of first short segment120connects with a first end126of a second turn128. Second turn128faces the opposite longitudinal direction as first turn116.

A second end130of second turn128connects with a first end134of a first mid-sized segment132. First mid-sized segment132is longer than first short segment120, but shorter than long segment108. A second end136of first mid-sized segment132connects with a first end138of a third turn140. Third turn140faces the opposite longitudinal direction as second turn128, thus facing the same longitudinal direction as first turn116.

A second end142of third turn140connects with a first end146of a second mid-sized segment144. Second mid-sized segment144is preferably the same length as first mid-sized segment132, but may be a different length. Second mid-sized segment144is longer than first short segment120, but shorter than long segment108. A second end148of mid-sized segment144connects with a first end150of a fourth turn152. Fourth turn152faces the opposite longitudinal direction as third turn140, thus facing the same longitudinal direction as second turn128.

A second end154of fourth turn152connects with a first end158of a second short segment156. Second short segment156is preferably the same length as first short segment120, but may be a different length. Second short segment156is shorter than long segment108, and is also shorter than both first and second mid-sized segments132,144. A second end160of short segment156connects with a first end162of a fifth turn164. Fifth turn140faces the opposite longitudinal direction as fourth turn528, thus facing the same longitudinal direction as both first turn116and third turn140. The second end166of the fifth turn164connects with the next adjacent series106.

Thus, band100has regions of shorter segments, regions of mid-sized segments, and regions of longer segments within the same circular band100. A stent having all of these regions can be more easily tracked in body vessels having bends of small radii, as will be described in detail more fully below.

Since third turn140is connected to first mid-sized segment132and second mid-sized segment144on its two ends138and142, third turn140forms a peak that is longitudinally offset from peaks formed at first and fifth turns116,164of the series106. In the particular series106labeled inFIG. 1, third turn140is disposed farther to the right than first turn116or fifth turn164.

Fourth turn152may be longitudinally aligned with second turn128, or longitudinally offset. Preferably, second turn128is longitudinally aligned with fourth turn152, because in a preferred embodiment, short segments120,156are the same length and mid-sized segments132,144are the same length. However, in other embodiments, short segments120,156may be of different lengths and mid-sized segments132,144may be of different lengths.

In the first embodiment depicted inFIGS. 1-4, each series106is connected to an identical adjacent series106. However, one skilled in the art can appreciate that each series106may have different sized long segments108, first and second short segments120and156, and first and second mid-sized segments132and144from the series106that is before or after it. In addition, series106may be connected to a different adjacent series (i.e., a series which does not have the LSMMS configuration of series106), as will be described in additional embodiments below.

FIG. 1shows band100having four full series106. However, any number of series106may be used in band100. For example, when band100is to be used in body lumens having large diameters, more series106may be used. Meanwhile, as few as two series106may be used in a band100for use in body lumens with small diameters.

In general, long segment108, first mid-sized segment132, and second short segment156are parallel, and first short segment120and second mid-sized segment144are parallel. InFIG. 1, long segment108, first mid-sized segment132, and second short segment156generally lean to the right, while first short segment120and second mid-sized segment144lean generally to the left. However, long segment108, first mid-sized segment132, and second short segment156may lean generally to the left, while first short segment120and second mid-sized segment144lean generally to the right, such as series106of band100bas shown and described inFIG. 2.

FIG. 2shows a portion of a stent having four bands100(100a,100b,100c, and100d) connected at connections268. Bands100aand100bare functionally the same. Band100bis a mirror image of band100a, and band100dis a mirror image of band100c. Therefore, bands100a,100b,100c, and100deach include a substantially similar pattern of segments and turns forming peaks and valleys. The bands are aligned to form adjacent bands such that each peak of a band is aligned with a valley of an adjacent band and each valley of a band is aligned with a valley of an adjacent band. For example, the peak at first turn116aof band100ais aligned with the valley formed by first turn116bof band100b. Similarly, the peaks at third and fifth turns140a,164aof band100aare aligned with the valleys formed at third and fifth turns140b,164bof band100b. Similarly, the valleys formed at second and fourth turns128a,152aof band100aare aligned with the peaks formed at second and fourth turns128b,152bof band100b. Where a peak of band100ais aligned with a valley of band100b, it can be seen that the closed end of the peak of band100afaces the closed end of the valley of band100b. Thus, when a valley of band100ais aligned with a peak of band100b, it can be seen that the open end of the valley of band100afaces the open end of the peak of band100b.

At least one connection268is formed where closed ends of turns of adjacent bands are aligned. In the embodiment ofFIG. 2, the offset peaks and valleys formed by first and second mid-sized segments132,144of a band are connected to the offset peaks and valleys formed by first and second mid-sized segments132,144of an adjacent band. The offset peaks and valleys of each band100a,100b,100c, and100dare formed by third turn140of the series106as described above, having first and second mid-sized segments132,144on either side of third turn140. For example, connection268is illustrated onFIG. 3between a peak at third turn140aof band100aand a valley at third turn140bof the adjacent band100b.

Connections268are preferably formed by welding the turns together, such as by resistance welding, friction welding, laser welding or another form of welding such that no additional materials are used to connect bands100. Alternatively, bands100can be connected by soldering, by the addition of a connecting element between the turns, or by another mechanical method. Further, as discussed above, the stent may be formed pre-connected as a unitary structure, such as by laser cutting or etching the entire stent body from a hollow tube or sheet. Other connections or ways to connect bands would be apparent to one skilled in the art and are included herein.

When adjacent bands100are connected together, a series270of consecutive tapered gaps is formed between consecutive unconnected aligned closed ends of turns of adjacent bands due to the various segment lengths of the LSMMS series described above. The series270of consecutive tapered gaps allows the stent to flex with little or no interference between adjacent bands when the stent is tracked around a small radius bend in a vessel.

The series270of consecutive tapered gaps includes four gaps272,274,276,278between connections268. If first and second short segments120,156are the same length and first and second mid-sized segments132,144are the same length, gaps274and276will be of equal length and gaps272and278will be of equal length. Due to the length of long segment108, gaps274and276are generally larger than gaps272and278. The larger gaps274and276occur at the second and fourth turns of each band, while smaller gaps272and278occur at the fifth and first turns of each band, respectively. The larger gaps274,276optimally occur between aligned closed ends of turns of adjacent bands which generally experience the greatest amount of interference when the stent is tracked around a small radius bend in a vessel.

Thus, the LSMMS series of various segment lengths form a series270of consecutive tapered gaps between the unconnected aligned closed ends of turns of adjacent bands which provides greater flexibility for the stent, and allows the stent to flex with little or no interference with adjacent bands when the stent is tracked around a small radius bend in a vessel. The consecutive tapered nature of series270is advantageous in that larger gaps274,276optimally occur between turns of adjacent bands which generally experience the greatest amount of interference when the stent is tracked around a small radius bend in a vessel. Smaller gaps272,278also add to the stent body's flexibility, while simultaneously providing greater scaffolding than that provided by larger gaps274,276. Greater scaffolding means that more area of the vessel walls is being supported directly by parts of the stent.

In addition to providing flexibility through the series270of consecutive tapered gaps, another important aspect of the present invention includes decreasing the length of the longest rigid element of the stent to further improve flexibility. The longest rigid element of a stent body occurs at the location of a connection268. Connection268and the longest two segments on either side of connection268essentially form a rigid element which must be tracked around the bends of a vessel. By minimizing the length of this rigid element, the length which must be tracked around the bends of a vessel is shortened and thus the stent is easier to advance.

FIG. 3illustrates the concept of a minimized rigid element380.FIG. 3shows a stent having two bands100(100a,100b) connected at connections268. Bands100aand100bare functionally the same. Band100bis a mirror image of band100a. The offset peaks and valleys formed by first and second mid-sized segments132a,144aof a band100aare connected to the offset peaks and valleys formed by first and second mid-sized segments132b,144bof an adjacent band100b. The offset peaks and valleys of each band100a,100bare formed by the third turns of the repeating series106as described above, having first and second mid-sized segments132,144on either side of the third turns. For example, connection268is illustrated onFIG. 3between third turn140aof band100aand third turn140bof the adjacent band100b. The length of rigid element380is decreased since mid-sized segments are on both sides of connection268.

FIG. 4shows a stent482having more than two bands100connected together to form a length484of the stent body. One of ordinary skill in the art will appreciate that stent482can have any number of bands100depending upon the desired length of stent482.

A stent can be expanded in several ways. Some stents are collapsed from a natural expanded shape into a collapsed state for delivery to the vessel. When a sleeve holding the stent in the collapsed shape is removed, the stent expands to its natural expanded state in the correct position within the lumen. Other stents are heat expandable. Once placed in the correct position, the stent is subjected to a heat source, which causes the expansion of the stent through a chemical reaction or natural thermal expansion, depending upon the material from which the stent is made. Still other stents are collapsed on top of a balloon, such as the type of balloon used in an angioplasty procedure. As the balloon expands, it physically forces the stent to expand at the same time. The balloon is then collapsed leaving the stent in the expanded position.

Preferably, the stent of the present invention is formed in a natural state, crimped onto a balloon dilation catheter for delivery to a treatment site and expanded by the radial force of the balloon. For example,FIG. 9is an illustration of a stent delivery system901in accordance with an embodiment of the present invention. Stent delivery system901includes a catheter903having a proximal shaft905, a guidewire shaft915, and a balloon907. Proximal shaft905has a proximal end attached to a hub909and a distal end attached to a proximal end of balloon907. Guidewire shaft915extends between hub909and a distal tip of catheter903through proximal shaft905and balloon907. Hub909includes an inflation port911for coupling to a source of inflation fluid. Inflation port911fluidly communicates with balloon907via an inflation lumen (not shown) that extends through proximal shaft905. In addition, hub909includes a guidewire port913that communicates with a guidewire lumen (not shown) of guidewire shaft915for receiving a guidewire917there through. As described herein, guidewire shaft915extends the entire length of catheter903in an over-the-wire configuration. However, as would be understood by one of ordinary skill in the art, guidewire shaft915may alternately extend only within the distal portion of catheter903in a rapid-exchange configuration. A stent formed from in accordance with an embodiment of the present invention is positioned over balloon907. However, one skilled in the art can appreciate that the stent of the present invention can be adapted for any type of delivery method.

The stent is preferably constructed of implantable materials having good mechanical strength. For example, a stent of one embodiment may be machined from implantable quality stainless steel bar stock. In another embodiment, a stent of the present invention could be made of any other metal suitable for implantation, such as cobalt based alloys (605L, MP35N), titanium, tantalum, superelastic nickel-titanium alloy, other biocompatible metals or thermoplastic polymers. Finally, although not required in all cases, the outside of the stent may be selectively plated with platinum to provide improved visibility during fluoroscopy.

Stents of the present invention may be formed using any of a number of different methods. For example, the stents may be formed by winding a wire or ribbon around a mandrel to form the pattern described above and then welding or otherwise mechanically connecting two ends thereof to form bands100. Bands100are subsequently connected together to form the stent body. Alternatively, stents may be manufactured by machining tubing or solid stock material into toroid bands, and then bending the bands on a mandrel to form the pattern described above. Bands100formed in this manner are subsequently connected together to form the longitudinal stent body. Laser or chemical etching or another method of cutting a desired shape out of a solid stock material or tubing may also be used to form stents of the present invention. In this manner, bands100may be formed connected together such that the stent body is a unitary structure. Further, a stent of the present invention may be manufactured in any other method that would be apparent to one skilled in the art. The cross-sectional shape of the finished stent may be circular, ellipsoidal, rectangular, hexagonal rectangular, square, or other polygon, although at present it is believed that circular or ellipsoidal may be preferable.

FIG. 5shows another embodiment of the present invention, illustrated as a flattened band500. Like band100, band500is a wire having an undulating pattern. The pattern includes a repeating series506of segments and turns. Like series106ofFIG. 1, the series506has five total segments, including a long segment508, a first short segment520, a first mid-sized segment532, a second mid-sized segment544, and a second short segment556. First and second mid-sized segments532,544are preferably the same length, while first and second short segments520,556are preferably the same length. Short segments520,556are shorter than mid-sized segments532,544, and mid-sized segments532,544are shorter than long segment508. The order of the five segments of series506has a LSMMS configuration (long, short, mid-sized, mid-sized, short).

In addition, the series506has five total turns, including a first turn516, a second turn528, a third turn540, a fourth turn552, and a fifth turn564. The segments and turns form valleys and peaks, in which peaks face the opposite longitudinal direction than valleys. The five turns516,528,540,552, and564connect the segments508,520,532,544, and556of the series506together in the same fashion described above with respect to series106. Since third turn540is connected to first mid-sized segment532and second mid-sized segment544, third turn540is longitudinally offset from first turn516and fifth turn564.

Unlike the embodiment ofFIGS. 1-4, in the embodiment depicted inFIGS. 5-6, series506is connected to a different adjacent series590(i.e., a series which does not have the LSMMS configuration of series106and series506). Series590includes five long segments592connected by five turns594. Long segments592are preferably substantially the same length as long segment508of series506, but may be different. Band500ofFIG. 5illustrates a total of four series connected together in the following order: a first series506, a first series590, a second series506, and a second series590.

FIG. 6shows a stent having four bands500(500a,500b,500c, and500d) connected at connections668. Bands500a,500b,500c, and500dare functionally the same. Band500bis a mirror image of band500a, and band500dis a mirror image of band500c. Therefore, bands500a,500b,500c, and500deach include a substantially similar pattern of segments and turns forming peaks and valleys. The bands are aligned to form adjacent bands such that the closed end of every other turn of a band is aligned with the closed end of every other turn of an adjacent band.

At least one connection668is formed aligned closed ends of turns of adjacent bands. In this embodiment ofFIG. 6, connections668occur at each of the offset peaks and valleys of a band formed by having first and second mid-sized segments532,544on either side of the peak or valley. In other words, the offset peaks and valleys formed by third turns540of a band are connected to the peaks and valleys formed at one of turns594of an adjacent band. The offset peaks and valleys of each band500a,500b,500c, and500dare formed by the third turns540of the repeating series506as described above, having first and second mid-sized segments (532,544) on either side of the third turn540. For example, connection668is illustrated onFIG. 6between third turn540cof series506on band500cand the third turn594of series590on adjacent band500b.

Connections668are preferably forming by welding the turns together, such as by resistance welding, friction welding, laser welding or another form of welding such that no additional materials are used to connect bands500. Alternatively, bands500can be connected by soldering, by the addition of a connecting element between the turns, or by another mechanical method. Further, as discussed above, the stent may be formed pre-connected as a unitary structure, such as by laser cutting or etching the entire stent body from a hollow tube or sheet. Other connections or ways to connect bands would be apparent to one skilled in the art and are included herein.

When adjacent bands500are connected together, a series670of consecutive tapered gaps is formed between consecutive unconnected aligned closed ends of turns of adjacent bands. The series670of consecutive tapered gaps allows the stent to flex with little or no interference between adjacent bands when the stent is tracked around a small radius bend in a vessel.

The series670of consecutive tapered gaps includes four gaps672,674,676,678between connections668. If first and second mid-sized segments532,544are the same length and first and second short segments520,556are the same length, gaps674and676will be of equal length and gaps672and678will be of equal length. Due to the length of long segment508, gaps674and676are generally larger than gaps672and678. The consecutive tapered nature of series670is advantageous in that larger gaps674,676optimally occur between turns of adjacent bands which generally experience interference when the stent is tracked around a small radius bend in a vessel. Smaller gaps672,678also add to the stent body's flexibility, while simultaneously providing greater scaffolding than that provided by larger gaps674,676. Greater scaffolding means that more area of the vessel walls is being supported directly by parts of the stent.

In addition to providing flexibility through the series670of consecutive tapered gaps, the embodiment depicted inFIGS. 5-6also incorporates a decreased length rigid element680. As explained above with respect toFIG. 3, decreasing the length of the longest rigid element of the stent further improves flexibility. The longest rigid element of a stent body occurs at the location of a connection668. Connection668and the longest two segments on either side of connection668essentially form a rigid element which must be tracked around the bends of a vessel. By decreasing the length of this rigid element, the length which must be tracked around the bends of a vessel is shortened and thus the stent is easier to advance. As described above, connections668occur at the offset peaks and valleys of a band formed by mid-sized segments532,544of a series506. In other words, the peaks and valleys formed by first and second mid-sized segments532,544of each band500are connected to an aligned closed end of a turn594of an adjacent band. Although long segments592occur on one side of connection668, the length of rigid element680is decreased since mid-sized segments532and544occur on the other side of connection668.

FIG. 7shows another embodiment of the present invention, illustrated as a flattened band700. Like band100, band700is a wire having an undulating pattern. The pattern includes a repeating series706of segments and turns. Like series106ofFIG. 1, the series706has five total segments, including a long segment708, a first short segment720, a first mid-sized segment732, a second mid-sized segment744, and a second short segment756. First and second mid-sized segments732,744are preferably the same length, while first and second short segments720,756are preferably the same length. Short segments720,756are shorter than mid-sized segments732,744and mid-sized segments732,744are shorter than long segment708. The order of the five segments of series706has a LSMMS configuration (long, short, mid-sized, mid-sized, short).

In addition, the series706has five total turns, including a first turn716, a second turn728, a third turn740, a fourth turn752, and a fifth turn764. These turns form valleys and peaks, in which peaks face the opposite longitudinal direction than valleys. The five turns716,728,740,752, and764connect the segments708,720,732,744, and756of the series706together in the same fashion described above with respect to series106. Since third turn740is connected to first mid-sized segment732and second mid-sized segment744, third turn740is longitudinally offset from peaks or valleys formed by first and fifth turns716,764.

Unlike the embodiment ofFIGS. 1-4, in the embodiment depicted inFIGS. 7-8, series706is connected to a different adjacent series795(i.e., a series which does not have the LSMMS configuration of series106and series706). Series795includes a total of five segments: a long segment796followed by four short segments797. The five segments are connected together by five turns798. Long segment796is preferably substantially the same length as long segment708of series706, but may be different. Further, short segments597are preferably substantially the same length as short segments720,756of series706, but may be different. Band700ofFIG. 7illustrates a total of four series connected together in the following order: a first series706, a first series795, a second series706, and a second series795.

FIG. 8shows a stent having four bands700(700a,700b,700c, and700d) connected at connections868. Bands700a,700b,700c, and700dare functionally the same. Band700bis a mirror image of band700a, and band700dis a mirror image of band700c. Therefore, bands700a,700b,700c, and700deach include a substantially similar pattern of segments and turns forming peaks and valleys. The bands are aligned to form adjacent bands such that the closed end of every other turn of a band is aligned with the closed end of every other turn of an adjacent band.

At least one connection868is formed between aligned closed ends of turns of adjacent bands. In this embodiment ofFIG. 8, connections868occur at each of the offset peaks and valleys of a band formed by having first and second mid-sized segments732,744on either side of the peak or valley. In other words, the offset peaks and valleys formed by third turns740of a band are connected to the peaks and valleys formed at one of turns798of an adjacent band. The offset peaks and valleys of each band700a,700b,700c, and700dare formed by the third turns740of the repeating series706as described above, having first and second mid-sized segments732,744on either side of the third turn. For example, connection868is illustrated onFIG. 8between third turn740cof series706on band700cand the third turn798bof series795on adjacent band700b.

Connections868are preferably formed by welding the turns together, such as by resistance welding, friction welding, laser welding or another form of welding such that no additional materials are used to connect bands700. Alternatively, bands700can be connected by soldering, by the addition of a connecting element between the turns, or by another mechanical method. Further, as discussed above, the stent may be formed pre-connected as a unitary structure, such as by laser cutting or etching the entire stent body from a hollow tube or sheet. Other connections or ways to connect bands would be apparent to one skilled in the art and are included herein.

When adjacent bands700are connected together, a series870of consecutive tapered gaps is formed between consecutive unconnected aligned closed ends of turns of adjacent bands. The series870of consecutive tapered gaps allows the stent to flex with little or no interference between adjacent bands when the stent is tracked around a small radius bend in a vessel.

The series870of consecutive tapered gaps includes four gaps872,874,876,878between connections868. If first and second mid-sized segments832,844are the same length and first and second short segments820,856are the same length, gaps874and876will be of equal length and gaps872and878will be of equal length. Due to the length of long segment808, gaps874and876are generally larger than gaps872and878. The consecutive tapered nature of series870is advantageous in that larger gaps874,876optimally occur between turns of adjacent bands which generally experience interference when the stent is tracked around a small radius bend in a vessel. Smaller gaps872,878also add to the stent body's flexibility, while simultaneously providing greater scaffolding than that provided by larger gaps874,876. Greater scaffolding means that more area of the vessel walls is being supported directly by parts of the stent.

In addition to providing flexibility through the series of consecutive tapered gaps870, the embodiment depicted inFIGS. 7-8also incorporates a minimized rigid element880. As explained above with respect toFIG. 3, minimizing the length of the longest rigid element of the stent further improves flexibility. The longest rigid element of a stent body occurs at the location of a connection868. Connection868and the longest two segments on either side of connection868essentially form a rigid element which must be tracked around the bends of a vessel. By minimizing the length of this rigid element, the length which must be tracked around the bends of a vessel is shortened and thus the stent is easier to advance. As described above, connections868occur at the offset peaks and valleys of a band formed by mid-sized segments732,744of a series706. In other words, the peaks and valleys formed by first and second mid-sized segments732,744of each band700are connected to an aligned closed end of a turn798of series795in an adjacent band. The length of rigid element880is decreased since mid-sized segments732and744occur on one side of connection868. In this embodiment, the length of rigid element880is further decreased since short segments797of series795occur on the other side of connection868.

FIG. 10shows an alternate embodiment of the present invention.FIG. 10illustrates a stent having more than two bands connected together.