Longitudinally flexible expandable stent

ES 2 235 532 T3

DESCRIPTION

Expandable and flexible stent in the longitudinal direction.

Field of the invention

The invention relates to a stent device for implantation in a body vessel, usually a blood vessel. More specifically, it relates to a tubular expandable stent with improved longitudinal flexibility.

Background of the invention

Stents are placed or implanted in blood vessels to treat strictures, narrowings, or aneurysms in them. They are implanted to reinforce collapsed, partially occluded, weakened, or dilated sections of a blood vessel. They are also implanted in the urinary tract and bile ducts.

Typically, the stent has an unexpanded (closed) diameter for placement and an expanded (open) diameter after placement in the vessel or canal. Some stents expand automatically and others mechanically expand with a radial force outward from inside the stent, such as the inflation of a balloon.

An example of the first type is found in US Patent No. 4,733,665 to Palmaz, issued March 29, 1988, which discloses a series of stent configurations for implantation with the aid of a catheter. The catheter includes an arrangement in which a balloon is inflated within the stent to expand the stent by plastic deforming after placement within a blood vessel.

In U.S. Patent No. 4,503,569 to Dotter, issued March 12, 1985, a type of self-expanding stent is described and a shape memory stent is disclosed that expands to an implanted configuration with a change of shape. temperature. Other types of self-expanding stents are also known that are not made of a shape memory material.

This invention is intended for stents of all types when configured to be longitudinally flexible, as described in more detail below. Flexibility is a convenient feature in a stent to be able to adapt to the curves of a vessel. Such stents are known in prior art. We have examples in US Patent No. 4,856,516 to Hillstead; US Patent No. 5,104,404 to Wolff; US Patent No. 4,994,071 to MacGregor; US Patent No. 5,102,417 to Palmaz; US Patent No. 5,195,984 to Schatz; US Patent No. 5,135,536 to Hillstead; US Patent No. 3,354,309 to Shepp-Pesch et al .; Lau's EPO patent application number 0 540 290 A2; Schatz EPO patent application number 0 364 787 B1 and PCT application WO 94/17754 (also identified as German patent application 43 03 181).

Generally speaking, these types of stents are articulated and are typically made up of a plurality of aligned, expandable, relatively inflexible, and circular segments that are connected to each other by means of flexible elements to form a generally tubular body that is capable of a degree of articulation or flexion. Unfortunately, one of the problems with this stent is that bending, overlapping, or interference can occur between adjacent segments on the inside of a curve due to the segments moving toward each other and, if they are in contact or on the outside of each other. a curve, can be separated from each other, leaving very large gaps. This can lead to inadequate vessel support, trauma to the vessel, flow problems, kinks, balloon explosions during expansion, and difficulties in recruiting devices to be installed through devices already implanted and in areas of the vessel without medium.

A diamond-shaped configuration with diagonal connections between each of the diamonds in each segment is also known, but such closed configurations have no flexibility.

In WO 96/26689 a stent is disclosed consisting of a plurality of meandering bands with connectors extending between adjacent meandering bands. The first and second ends of each connector are offset circumferentially and longitudinally from each other. In WO 98/20810 a stent is disclosed having a plurality of zigzag bands, adjacent to which are connected by means of a diagonally extending connecting element. In DE 297 16 476 a stent formed by a network of cables consisting of longitudinal rows of cable in wave forms is disclosed. Adjacent wave rows are connected by jumper wires which may include curvature. In EP 0 876 806 a stent formed by series of annular segments with connectors between them is disclosed. The connectors have an S-shaped configuration.

An object of this invention is to provide a longitudinally flexible stent of open configuration that avoids these problems and exhibits improved flexibility (radially and longitudinally) in the stent body segments thereof rather than at the flexible junctions between the segments. It is also another object of the present invention to provide a stent that is flexible but also allows access to side branches.

The objects of the invention are achieved according to claim 1.

Summary of the invention

It is an object of the present invention to provide a flexible stent formed by interconnected bands that provides access to lateral branches and that further avoids the problem of pinching or overlapping between adjacent bands. Pinching or overlapping is avoided where the peaks and concavities of the adjacent bands are displaced in circumference relative to each other. The stents of the present invention achieve this objective by having different bands characterized by different wavelengths along the stent and / or by arranging the interconnecting members in such a way that, after expansion of the stent, the phase relationship between the Adjacent bands are altered by displacing the peaks and concavities in circumference relative to each other.

The expandable stents of the invention are formed by a plurality of interconnected band-shaped elements characterized by alternating peaks and concavities. The ends of the interconnecting members joining adjacent bands are offset in circumference and optionally offset longitudinally. The peaks and concavida2

ES 2 235 532 T3 from the adjacent bands are also offset in circumference so that the stent, in an expanded state, has minimal overlap of peaks and concavities.

To this end, the invention provides an expandable, flexible, tubular stent consisting of a plurality of elements in the form of undulating bands of a selected wavelength or lengths. The banded elements have peaks and concavities and are aligned on a common longitudinal axis to define a generally tubular stent body. The peaks and concavities generally have a longitudinal direction along the body of the stent. Adjacent band elements can be in phase or out of phase with each other. The stents of the invention further comprise a plurality of interconnecting elements having first ends and second ends. The first and second ends extend from the adjacent banded elements and move relative to each other in a longitudinal direction and in a radial direction along the stent. It is desirable that, as the stent expands, at least some of the peaks and concavities of a given band element are displaced relative to each other around the periphery of the stent to adjust the longitudinal flex of the stent in the shaped elements. band and without interference between adjacent band elements.

In the stent there are two different types of band-shaped elements, first band-shaped elements with a selected first wavelength and second band-shaped elements with a second selected wavelength that exceeds the first selected wavelength, The first and second band-shaped elements alternate throughout the stent. Although the terminology of "first band-shaped element" and "second band-shaped element" is used, it is not intended to convey the order of appearance of the elements of the stent of the invention.

Brief description of the figures

Figures 4a, b; 5A, b and 6 to 15 do not show embodiments of the present invention.

Figure 1a shows a banded element used in the stents of the invention.

Figure 1b shows a schematic of a peak region containing a double peak and a concave region containing a double concavity.

Figure 2 shows a one-dimensional view of a stent configuration according to the invention.

Figure 3 shows the pattern of Figure 2 in a tubular stent.

Figure 4a shows a one-dimensional view of a stent configuration.

Figure 4b shows a one-dimensional view of a stent configuration.

Figure 5a shows a one-dimensional view of a stent configuration.

Figure 5b shows a one-dimensional view of a stent configuration.

Figure 6 shows a one-dimensional view of a stent configuration.

Figure 7 shows a one-dimensional view of a stent configuration.

Figure 8 shows a one-dimensional view of a stent configuration.

Figure 9 shows a one-dimensional view of a stent configuration.

Figure 10 shows a one-dimensional view of a stent configuration.

Figure 11 shows a one-dimensional view of a stent configuration.

Figure 12 shows a one-dimensional view of a stent configuration.

Figure 13 shows the pattern of Figure 12 in a tubular stent.

Figure 14 shows an expanded stent of the configuration shown in Figure 12.

Figure 15 shows a one-dimensional view of an alternative stent configuration.

Detailed description of the invention

Although this invention may be represented in many different ways, specific preferred embodiments of the invention are described in detail herein. This invention is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated.

For consistency, the terms "peak" and "concavity" will be defined with respect to the proximal and distal ends of the stent. Each of the stents has a proximal end 91 and a distal end 93 and a longitudinal axis 95, as shown in Figure 1a. Spikes 36 are generally concave relative to the proximal end of the stent and generally convex relative to the distal end of the stent. The concavities 40, on the other hand, are generally convex relative to the proximal end of the stent and generally concave relative to the distal end of the stent. Despite this definition, the term peak is also extended to regions 48 that generally resemble peaks and that, however, may contain regions in the form of concavities in the peak-like region, as shown in Fig. Figure 1b. Similarly, the term "concavity" is also intended to extend to regions 52 that generally resemble concavities which, however, may contain peak-like regions in the concave-like region, as shown in FIG. 1b.

Corresponding to each peak 36 is an inner diameter peak 38 at which the inner diameter of the band-shaped element reaches its peak. The set of points on a given band-shaped element that are distal to the internal diameter peak 38 is called the peak region 48. Similarly, corresponding to each concavity 40, there is an internal diameter concavity 42 in which the diameter internal band-shaped element reaches its concavity. The set of points on a given band-shaped element that are proximal to a concavity of internal diameter 42 is called the region of concavities 52. For the sake of clarity, unless otherwise indicated, analogous parts of stents will have labels similar, using three-digit reference numerals to distinguish between the various embodiments shown.

Also included in this definition of peak regions and trough regions are peak regions consisting of multiple peaks as well as trough regions consisting of multiple troughs such as those shown schematically in Figure 1b. Peak 36 consists of two sub-peaks 36a, b, and concavity 40 also consists of two sub-peaks 40a, b. In the case of peaks

ES 2 235 532 T3 containing sub-peaks and the concavities containing sub-concavities, the region of peaks 48 includes all points along the band-shaped element between the sub-peaks that form the peak and, likewise, the region of concavities 52 includes all points along the band-shaped element between the sub-concavities that form the concavity.

The stents of the invention include one or more short-wavelength, low-amplitude bands to provide flexibility and one or more long-wavelength, high-amplitude bands to provide access to the lateral branch or to provide alternative resistance sections such as , for example, soft and / or hard sections.

Returning to the figures, figure 2 shows a one-dimensional view of a stent configuration and figure 3 shows the stent of figure 2 in tubular form. That is, the stent is shown for clarity in Figure 2 in one-dimensional form and can be manufactured from a one-dimensional pattern 110 (Figure 2) that is formed of a tubular shape by rolling the pattern to join edges 112 and 114 to each other (figure 2). The edges can then be joined by welding or a similar procedure to achieve a cylindrical configuration as generally shown at 115 of Figure 3.

A more preferred manufacturing procedure begins with a thin-walled tube that is then laser cut to the desired configuration. It can also be chemically etched or electrically discharge machined (EDM) to form a suitable configuration.

In these figures, the configuration is seen to be formed by one or more spaced first band-shaped elements 120. The first band-shaped elements have a meandering configuration to obtain continuous waves for the first band-shaped elements. The waves are characterized by a plurality of peaks 124 and concavities 128 running in a generally longitudinal direction along the cylinder such that the waves from the first band-shaped elements 120 open up as the stent expands from from an unexpanded state with a first diameter to an expanded state with a second diameter.

The stent further comprises a plurality of spaced second band-shaped elements 132 that generally have a meandering configuration to provide continuous waves to the second band-shaped elements. The waves are characterized by a plurality of peaks 136 and concavities 140 that run generally in a longitudinal direction along the cylinder such that the waves from the second band-shaped elements open up as the stent expands from an unexpanded state with a first diameter to an expanded state with a second diameter. The first and second band-shaped elements are characterized by their respective wavelengths and amplitudes with the wavelength and amplitude of the second band-shaped elements exceeding the wavelength and amplitude of the first band-shaped elements. band.

The first band-shaped elements 120 and adjacent second band-shaped elements 132 are connected to each other by means of a plurality of interconnecting elements 144. The ends of the interconnecting element are circumferentially offset from each other.

As shown in Figures 2 and 3, the first band elements 120 and the second band elements 132 alternate along the stent. Optionally, as shown in Figures 2 and 3, each end 152 of the stent may terminate in a first band-shaped element. However, the invention also contemplates that each end ends in a second band-shaped element, or likewise, one end ends in a first band-shaped element and the other end ends in a second band-shaped element.

Although a minimum of one connecting element is needed to join adjacent band elements, it is preferable to have two or more interconnecting elements. In one embodiment, as shown in Figures 2 and 3, the first and second adjacent band elements 120 and 132 are connected with three interconnecting elements 144. Also, in one embodiment, the adjacent interconnecting elements 144 extending from peaks 136 in a first band-shaped element 120 are separated by five peaks in the first band-shaped element, while the interconnecting elements Adjacent recesses 144 extending from recesses 140 in a second band-shaped element 132 are separated by three recesses in the second band-shaped element.

It is also another function of the present invention that the peaks 124 of the first band-shaped elements 120 are offset in circumference of the periphery of the stent from the concavities 140 in the second adjacent band-shaped elements 132. It is desirable that the peaks and concavities are offset in the expanded state of the stent to minimize the possibility of pinching or overlapping between adjacent band-shaped elements.

Although the stent of Figure 2 consists of two band-shaped elements with a different wavelength, the invention contemplates stents with a plurality of band-shaped elements with a different wavelength. Thus, other stents may have three, four, or more band elements with a different wavelength.

Stents consisting of band-shaped elements with a single wavelength, connected to each other by means of interconnecting elements, do not form part of the present invention. Returning to Figures 4a and 4b, the band-shaped elements 220a, b are connected to each other by means of interconnection elements 244a, b. The band-shaped elements 200a, b are 180 ° out of phase with each other. In the compressed state, the band-shaped elements consist of a plurality of peaks 236a, b, and concavities 240a, b. Peak region 248a, b, and recess region 252a, b have been shaded in one of the examples for illustrative purposes.

In Figure 4a, each interconnecting element 244a extends between a region of spikes 248a and a region of recesses 252a. The rectilinear interconnecting elements 244a consist of a first rod 280a, a second rod 284a, and a link 288a positioned between the first and second rods 280a and 284a. The first stem 280a extends in the longitudinal direction from the peak region 248a

ES 2 235 532 T3 and is substantially perpendicular to link 288a. The second stem 284a extends in the longitudinal direction from the recess region 252a and is perpendicular to the link 288a.

In Figure 4b, the stent differs from the embodiment of Figure 4a in that interconnect element 244b which extends between a region of spikes 248b and a region of recesses 252b that is curvilinear rather than rectilinear.

In both Figures 4a and 4b, the interconnecting elements appear to emanate from the middle of the peak and trough regions.

In Figure 5a, the stent of the invention consists of band-shaped elements 320a of a single wavelength, connected to each other by means of interconnection elements 344a. Adjacent band-shaped elements 320a are 180 ° out of phase with each other. The band-shaped elements consist of a plurality of peaks 336a and recesses 340a. Interconnecting elements 344a extend between a region of spikes 348a and a region of recesses 352a. Peak regions 348a and recess regions 352a from which interconnecting elements 344a emerge in a given band-shaped element 320a extend longitudinally beyond adjacent peak regions 348a 'and recess regions 352a' from which does not extend any interconnection element. The extent is such that at least a portion of the peak regions 348a overlaps longitudinally along the stent with at least a portion of the recess region 352a in an adjacent band element 320a '. Obviously, the overlap is limited to the longitudinal direction and not to the circumferential direction.

As shown in FIG. 5b, interconnecting elements 344b extend between peak region 348b and the second closest recess region 352b in an adjacent band-shaped element. Interconnecting elements 344b are perpendicular to the longitudinal axis. Like the stent of FIG. 5a, the peak regions 348b from which the interconnecting elements 344b extend and the recessed regions 352b from which the interconnecting elements 344b extend can extend beyond the interconnecting regions. adjacent peaks 348b 'and concavity regions 352b', from which no interconnecting element 344b emerges.

As shown in FIG. 6, adjacent band elements 420 are in phase with each other. As in the previous figures, the band-shaped elements 420 are of a single wavelength, and are connected to each other by means of interconnecting elements 444. The band-shaped elements consist of a plurality of peaks 436 and concavities 440. The interconnecting elements 444 extend at an oblique angle relative to the longitudinal axis of the stent between a region of spikes 448 and a region of recesses 452. As such, the ends of the interconnecting elements 444 are offset in circumference relative to each other. others. The exact angle will obviously depend on the region from which the interconnecting elements extend, as well as whether the interconnecting elements connect the nearest peaks and concavities, the next closest peaks and concavities, or the peaks and concavities together. further apart.

In Figures 5a, 5b and 6, the interconnecting elements emerge from the sides of the peak and trough regions.

Although for the embodiments of Figures 1-6, the interconnecting elements extend from regions of peaks in band-shaped elements to regions of recesses in adjacent band-shaped elements, The invention also contemplates that the interconnecting elements extend from a position between a region of peaks and an adjacent region of concavities in a band-shaped element to an intermediate position between a region of concavities and a region of peaks in a second element. in the form of an adjacent band, like the one shown in Figure 7.

In Fig. 7, the interconnecting elements extend from a region between the peak region and the recess region into a band-shaped element. The stent is formed of adjacent band-shaped elements 520 that are 180 ° out of phase with each other. The interconnection elements 544 extend from an intermediate region between a region of spikes 548 and a region of recesses 552 in a band-shaped element to an intermediate region between a region of spikes 548 and a region of recesses 552 in an element in adjacent band shape. Interconnecting elements 544 consist of a first stem 560, a second stem 564, and an intermediate member 568 positioned between the first and second stem 560 and 564. The first stem 560 and the second stem 564 are substantially perpendicular to the intermediate member 568 extending in the longitudinal direction. Although not illustrated, the region from which interconnecting elements 544 exit may be midway between the peaks and the recesses.

Figure 7 also differs from Figures 26 in the orientation of the interconnecting elements. While the interconnecting elements of Figures 2-6 are oriented similarly, in Figure 7, the orientation of the interconnecting elements alternates between adjacent pairs of adjacent band-shaped elements. Specifically, the second rods 564 'of the interconnecting elements 544' travel in a clockwise circumferential direction along the stent relative to the first rods 560 ', and the second rods 564 "of the interconnecting elements 544 "are displaced in a circumferential direction counterclockwise along the stent relative to the first stem 560".

This function is also shown in Figure 8, in which interconnecting elements 644 connect adjacent in-phase band-shaped elements 620 together. Interconnecting elements 644 extend at an oblique angle relative to the longitudinal axis of the stent, between a region of peaks 648 and a region of recesses 652. As in Figure 7, the orientation of the interconnecting elements alternates between adjacent pairs of adjacent band-shaped elements. Specifically, the distal ends of the interconnecting elements 644 'are oriented in a circumferential direction along the stent counterclockwise relative to the proximal end of the interconnecting elements, while the distal ends of

ES 2 235 532 T3 the interconnecting elements 644 "are offset in a circumferential direction along the stent in a clockwise direction relative to the proximal ends.

Although in the stents of Figures 2-8, the adjacent bands are connected by means of five interconnecting elements, more or fewer interconnecting elements can be used. Furthermore, although the interconnecting elements appear separated from one another by three peaks and three concavities, other separations are also contemplated.

In the stent of FIG. 9, each band-shaped element 720 consists of peaks 736 of more than one width and recesses 740 of more than one width. The high amplitude peaks 736a and the small amplitude peaks 736b alternate as the high amplitude concavities 740a and the small amplitude concavities 740b. The interconnecting elements are oriented at an oblique angle relative to the longitudinal axis 795 of the stent.

As shown in Figure 10, each band-shaped element 820 consists of peaks 836 of more than one amplitude and concavities 840 of more than one amplitude, however, peaks of the same amplitude are grouped into one element in band shape like concavities of the same width. It should also be noted that in the embodiment of Figure 10, the location of a group of peaks of a given amplitude varies in circumference along the length of the stent. Interconnecting elements 844 connect peaks 836 and recesses 840 into adjacent band-shaped elements 820. If there are several peaks of different amplitudes in a band-shaped element, the invention further contemplates the possibility of interconnecting elements extending from large peaks 836a to large concavities 840a as in Figure 9, in addition to the possibility of interconnecting elements. interconnection extending from large peaks to small concavities or from small peaks 836b to large concavities 840a, as shown in the figure

10. Also, the interconnection elements between any two adjacent band-shaped elements can be of different lengths, as shown in Figure 10, and start at different longitudinal positions on one band-shaped element. Interconnect element 844a is longer than interconnect element 844b. The interconnecting elements are oriented at an oblique angle relative to the longitudinal axis 895 of the stent. Interconnect element 844a is oriented at a smaller oblique angle relative to the longitudinal axis of the stent than interconnect element 844b.

It should also be noted that in the stent of Figure 10, all the concavities 840a, b of a given band-shaped element 820 are longitudinally aligned along the stent and differ only in their position in circumference along of the stent.

It should also be noted that the stent of Figure 10 consists of a first group of interconnecting elements 844a and a second group of interconnecting elements 844b. The interconnecting elements of the first group are parallel to each other and positioned at an oblique angle relative to the longitudinal axis different from that of the members of the second group that are parallel to each other. Thus, the invention contemplates stents having several different groups of obliquely positioned interconnecting elements in which the oblique angle differs in each group.

As shown in Figure 11, each band-shaped element 920 consists of peaks 936a, b of different amplitudes and concavities 940, however, the peaks of the same amplitude are grouped into a band-shaped element like the concavities of the same width. It should also be noted that in the embodiment of Figure 11, the location of the groups of peaks of a given amplitude of a band-shaped element varies circumferentially along the stent. Interconnecting elements 944 connect high amplitude peaks 936a and small amplitude concavities 940b in adjacent band-shaped elements. Similarly, interconnecting elements 944 also connect small amplitude peaks 936b and large amplitude concavities 940a.

Also, the interconnection elements between any two adjacent band-shaped elements can be of different lengths from each other and can be positioned at different oblique angles.

It should also be noted that in the stent of Figure 11, the large amplitude portions 999 of the band-shaped element 920 are placed symmetrically about the center 1001 of the band-shaped element as are the small parts. amplitude 998. The center 1001 of the band-shaped element is defined as a ring that traverses a path midway between the large peaks 936a and the large concavities 940a of the band-shaped element. This function can also be seen in the embodiment of figure 9.

A flexible, tubular, expandable stent has a longitudinal axis consisting of one or more first cylindrical shaped segments. The first cylindrical shaped segments 20 shown in Figure 1 have first struts 23 having first 25 and second 27 ends. The first segments 20 are defined by means of a member formed in an undulating pattern of paired first struts 23 connected to each other, in which the adjacent pairs of first struts 29 'and 29 "in a given first segment 20 are connected to each other at opposite ends 31 'and 31 ", respectively. Adjacent segments are connected to each other.

The stent is seen more clearly in Figures 2-8. As shown, the stent of Figure 3, in addition to consisting of first segments 120 that are defined by an undulating pattern of paired and interconnected first struts 123 in which the adjacent pairs of first struts 129 and 129 "of a first determined segment 120 are connected to each other at opposite ends 131 'and 131 ", respectively, the stent also consists of one or more second cylindrical shaped segments 132, each second segment being defined by a member formed in an undulating pattern of paired second struts connected together 135 and in which adjacent pairs of second struts 137 'and 137 "of a given second segment 132 are connected to each other at opposite ends 139 'and 139 ”, respectively. The first struts 123 are shorter than the second struts 1 35. The first segments 120 are formed

ES 2 235 532 T3 by a series of first struts 123 and the second segments 132 are formed by a series of second struts 135, the number of first struts of a first segment exceeding the number of second struts of a second segment. The first and second segments 120 and 132 are aligned on a common longitudinal axis 195 to define a generally tubular stent body, generally shown at 115. The first and second segments 120 and 132 alternate throughout the body of the stent. Adjacent first and second segments 120 and 132 alternate throughout the stent body. Adjacent first and second segments 120 and 132 are connected by means of a plurality of interconnecting elements 144. Each interconnect element 144 extends from an end 131 "of paired first struts in a first segment 120 to an end 139" of paired second struts in an adjacent second segment 132. The ends of interconnect elements 144 are offset in circumference by relationship to each other.

It is preferable that, as stent 155 expands, paired struts 129 "and 137" of adjacent segments 120 and 132 move relative to each other on the periphery of the stent body to accommodate longitudinal flexure of the stent in the segments. and without interference between adjacent segments.

As shown in Figures 4a, b, the cylindrical shaped segments 220a, b are formed by interconnected struts 223a, b having first 225 and second 227 ends. Adjacent pairs of struts 229a, b 'and 229a, b "of a given segment 220a, b are connected to each other at opposite ends 231a, b' and 231a, b", respectively. Adjacent segments are connected by means of a plurality of interconnecting elements 244a, b. Each interconnecting element 244a, b extends from one end of paired struts 231a, b "of one segment to one end of paired struts 231a, b 'of an adjacent segment. The first end 245a, b and the second end 247a, b of the interconnecting elements 244a, b are offset in circumference along the stent.

A similar structure is found in the stents of Figures 5a, b and 6-8 indicated by like reference numerals.

In particular, as shown in Figure 8, cylindrical shaped segments 620 of interconnected struts 623 are formed, having first 625 and second 627 ends. Segments 620 are defined by means of a member formed in an undulating pattern of interconnected paired struts 623 in which pairs of adjacent struts 629 'and 629 "of a given segment 620 are connected to each other at opposite ends 631' and 631 ”respectively. Segments 620 are aligned on a common longitudinal axis 695 to define a generally tubular stent body. Adjacent segments are connected by means of a plurality of interconnect elements 644 (and 644 ') having first 645 (645') and second 647 (647 ') ends, each interconnect element 644 (644') extending from one end. of paired struts 631 "from one segment to one end of paired struts 631 'from an adjacent segment. The first end 645 (645 ') and the second end 647 (647 ") are offset in circumference along the stent.

Additional stents are shown in Figures 12-15. Figure 12 and Figure 13 show a fragmentary one-dimensional view of an unexpanded stent configuration and the actual (unexpanded) tubular stent, respectively. That is, the stent is shown in Figure 12 in a one-dimensional fashion for clarity and may be formed of a flat pattern 1110 (Figure 12) that becomes tubular in shape by rolling the pattern so that edges 1112 and 1114 meet. (figure 12). The edges can then be joined by welding or a similar procedure to obtain a configuration like the one shown in figure 13.

In these figures it is appreciated that the configuration is formed by a plurality of adjacent segments generally indicated at 1116, each of which is formed in a flexible undulating pattern of substantially parallel struts 1118. The strut pairs are connected to each other in alternating end portions 1119a and 1119b. As shown in FIG. 12, the interconnected end portions 1119b of one segment are positioned opposite the interconnected end portions 1119a of adjacent segments. The end parts, shown are generally elliptical, but can be round, square, pointed, or otherwise. Any end part configuration is acceptable as long as it provides a wavy pattern, as shown. When the flat shape 1110 is formed in an unexpanded tube as shown in Figure 13, the segments are cylindrical but the end portions 1119 of the adjacent segments are still in an opposite position relative to each other.

A more preferable manufacturing process begins with a thin-walled tube which is then laser cut to the desired shape. It can also be chemically machined or EDM machined to achieve the proper configuration.

The interconnecting elements 1120 extend from a part of the end 1119 of one segment 1116 to another part of the end 1119 of another adjacent segment 1116, but not to an end part positioned on the opposite side 1119 of an adjacent segment 1116. At least there is three struts included between the points on either side of a segment 1116 where an interconnecting element 1120 contacts a portion of the end 1119. This results from the interconnecting elements 1120 extending in an angular direction between the segments around the periphery of the tubular stent. The interconnecting elements 1120 are preferably of the same length, but may vary from segment to segment. Furthermore, the diagonal direction can be reversed from segment to segment extending upward in one case and downward in another, although all connecting elements between any pair of segments are substantially parallel. Figure 12, for example, shows them extending downward, from right to left. In this configuration, if they extended upward, they would go from left to right.

As a result of this angular extension of interconnecting elements 1120 between adjacent segments and loops, as the stent expands as shown in Figure 14, the closest adjacent end portions 1119 between segments 1116

ES 2 235 532 T3 are displaced from each other and are no longer opposed to each other in order to minimize the possibility of bending or overlapping between the segments, that is, pinching.

The number of interconnection elements 1120 may vary depending on the circumstances of each particular case. Three per segment is satisfactory for the configuration shown, and at least three are typically used.

The alternative design shown in Figure 15 includes longer struts 1118a in the two end segments 1116a than in the intermediate segments 1116. This allows the end segments (1116a) to have less compressive strength than the end segments 1116a. intermediates (1116), providing a more gradual transition from the native container to the stent support structure. Otherwise, the configuration is the same as shown in figure 12.

As indicated in the figures, the invention contemplates a variation of the shapes of the interconnecting elements that ranges from rectilinear shapes to curvilinear shapes. The invention further contemplates embodiments in which all interconnecting elements are oriented similarly, as well as embodiments in which adjacent sets of interconnecting elements extend between adjacent pairs of segments that are oriented oppositely (e.g., Figures 7 and 8). The invention also contemplates the use of interconnecting elements that extend from a variety of positions along the segments, ranging from various positions in the area where the paired struts connect to each other to other positions along the struts.

The invention also contemplates the possibility for the interconnecting elements to extend at an oblique angle relative to the longitudinal axis of the stent and to connect adjacent peaks and concavities in adjacent segments, as well as peaks and concavities in adjacent segments that are separated by one or more peaks and / or concavities.

The invention also contemplates changing the orientation of the interconnecting elements.

Lastly, there are preferably at least three interconnecting elements joining adjacent first and second segments, although fewer or more interconnecting elements are also contemplated.

It is understood that the peaks and concavities of the present invention must be rounded, as shown in the figures. The peaks and concavities can be bulbous, triangular, square, pointed, or can be formed by straight sections connected to each other.

As noted, this invention applies to self-expanding configurations, mechanically expandable configurations, and a wide variety of materials, including metals and plastics and any other material that is capable of operating in an expandable stent. . For example, the stent can be made of metal wire or tape, such as tantalum, stainless steel, or a similar material. It can have thin walls. It may have a shape memory alloy like Nitinol or something similar. The interconnecting elements may be integrally formed by band-shaped elements (or segments) or they may be attached to them through such a process such as, for example, adhesive bonding, welding or any other known bonding process.

Only the examples referring to Figures 2 and 3 reveal the present invention. The above examples and description are provided for illustrative purposes only and not exhaustive. These examples and their description suggest various variations and alternatives to one of ordinary skill in the art. Alternatives and variations are within the scope of the appended claims.