Abstract:
A catheter for detachably receiving an expandable and/or decollapsible or unfoldable, respectively, implant, in particular a stent may include at least one assembly for controlling the expansion and/or the unfolding or decollapsing, respectively, of the implant from a first diameter to a second diameter and/or its return back from the second diameter to the first diameter. Furthermore, an implant, in particular a stent, and a set including a catheter and an implant are proposed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is filed under 35 U.S.C. §371 as a U.S. national phase application of PCT/EP2009/001464, having an international filing date of Mar. 2, 2009, which claims the benefit of German Patent Application Nos. 10 2008 012 113.4, having a filing date of Mar. 2, 2008; 10 2008 013 381.7, having a filing date of Mar. 10, 2008; and 10 2008 013 948.3, having a filing date of Mar. 12, 2008, all of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a catheter, an implant, and a set including a catheter and an implant. 
     BACKGROUND 
     In medicine, stents, or implants in general, are used for keeping vessels (especially: blood vessels) or tubes (especially trachea, esophagus, stomach, intestine, urethra, ureter) open. They are inserted or advanced, respectively, to the implantation site in a folded or collapsed, respectively, or crimped manner by using a catheter. At this site, the unfolding or decollapsing, respectively, of folded or collapsed stents is effected by removing an outer sleeve, which is arranged over or about the folded or collapsed stent, by means of reset or restoring forces; or by means of a balloon arranged inside the stent, which expands the stent encircling or encompassing the balloon when being inflated or blown up, respectively. Usually, stents are made from bio-compatible steel. Once unfolded or decollapsed, respectively, or expanded, it is difficult or impossible to return the stent back to a reduced diameter. The latter is regularly important if a stent which is placed incorrectly in the target organ (vessel or another organ, see above) has been unfolded or expanded; a stent which has been expanded or unfolded at the wrong site can generally not be re-implanted without having the possibility to reduce its diameter. 
     It may be desirable to propose a catheter for returning an implant, in particular a stent, back to a reduced diameter after having unfolded and/or expanded the stent at the implantation site. In addition, an implant, in particular a stent, which is suited hereto shall be proposed. Furthermore, a set including a catheter and an implant shall be presented. 
     SUMMARY 
     Thus, according to the invention, there is proposed a catheter for detachably receiving an expandable and/or decollapsible or unfoldable, respectively, implant, in particular a stent, wherein the catheter comprises at least one means for controlling the expansion and/or the unfolding or decollapsing, respectively, of the implant from a first diameter to a second diameter and/or for returning back the implant from the second diameter to the first diameter; or is prepared for receiving such a means. 
     According to the invention, expanding or unfolding or decollapsing, respectively, is understood as enlarging the diameter of the implant. Thereby, the non-expanded or non-unfolded or non-decollapsed, respectively, diameter (which can also be referred to as a first diameter, wherein also another diameter which is smaller than the second diameter mentioned below can be understood as a first diameter in the sense of the present invention) can be a diameter of the implant immediately before its insertion into the patient&#39;s body. In returning the diameter back from a second diameter (which is larger than the first diameter) to an arbitrary reduced diameter (the first diameter), the diameter is diminished or reduced, respectively. Returning (back) can be accomplished by a (completely or partly) re-folding or a reversed expanding procedure. According to the invention, during the returning procedure, the implant does not necessarily have to be brought into a shape that it occupied or passed through during unfolding or expanding. 
     In case a diameter of the implant could not be determined, expanding or unfolding or decollapsing, respectively, is understood as an increase in a direction or dimension of the implant which effects an elongation of a periphery or circumference, respectively, of the implant in a plane perpendicular to the longitudinal direction of the implant explained further below. 
     According to the invention, receiving an implant by the catheter is understood as any functional connection between the implant and the catheter. Thereby, a transmission of power or forces, respectively, can take place, but does not have to take place. The connection can be provided as a frictional or form closure connection or neither as a frictional nor as a form closure connection. 
     According to the invention, “controlling” also includes adjusting or setting or regulating, respectively. Thereby, it can be adjusted or set or regulated, respectively, to a voltage value, a pressure value or the like. 
     According to the invention, “detachably receiving” is understood as a separable or dividable conjunction or association between the catheter and the implant. An example for a separable or dividable conjunction is crimping a stent onto a catheter for advancing or inserting the stent to the implantation site. 
     The catheter according to the invention advantageously allows for a controlled unfolding or decollapsing, respectively, and re-folding or re-collapsing, respectively, (which can also encompass or include expanding and returning back to a reduced diameter) of the implant, for example, when being arranged inside the implant. Thus, it is advantageously possible to return or bring the implant back to a smaller diameter again and thus re-implant it after its expansion or unfolding, i. e., to shift it at the implantation site. If there should be detected during implantation that an implant of wrong size or design or construction, respectively, had been chosen, the implant could advantageously be replaced even after its expansion/unfolding. 
     Thereby, the catheter can be connected to or communicate, respectively, with the implant via the means for controlling. The unfolding or decollapsing, respectively, and the folding or collapsing, respectively, of the implant can be performed without the aid of an outer sleeve. 
     The catheter can comprise a plastic or synthetic material or a copolymer or can be manufactured by means of two- or multiple-component technologies. According to the invention, the catheter can comprise a metal (steel or alloy). The catheter can be stiff; however, it can also be designed flexible or bendable, in order to be able to adapt it to or align it with defined or certain conditions. Thereby, the catheter can be manually bendable or it can be controlled for bending by means of a mechanism which can, e. g., be integrated in the catheter. The catheter can be bendable in a passive manner, e. g., by advancing or inserting it along the vessel or body lumen alone. 
     Independent of any other feature, i. e., without having to comprise any other feature in combination, the catheter can comprise a mechanically enforced or reinforced section, in particular in a tip area of the catheter, and in particular in a section which also comprises at least one of the passage means. 
     The catheter can have a circular or oval or rectangular cross-section. The catheter can also have a non-circular, a non-oval or a non-rectangular cross-section. Furthermore, the cross-section of the catheter can be unchanged across the whole catheter. However, it can also have two or three or more different cross-sections along its longitudinal axis and in particular in the area for receiving the implant. 
     The unfolding and folding of the implant which is controlled by the catheter can take place outside and inside a patient&#39;s body. 
     The catheter can be designed such as described in, e.g., US 2007/0100427 A1 by Perouse or in US 2005/0075731 A1 by Artof et al. By way of reference, the contents thereof are each subject-matter of the present invention. This particularly applies for the materials and (part) geometries given therein. 
     The catheter can be a one-lumen catheter; it can have no lumen and it can be a multi-lumen catheter. If it is a multi-lumen catheter, the catheter can be a two- or three- or multi-lumen catheter having equally or differently sized lumina in or regarding its cross-section. 
     Thus, in a preferred embodiment of the present invention, a catheter having a plurality of lumina in longitudinal direction or channels (hereinafter also designated in short: channel or channels) for guiding reins is proposed. The lumina or channels can serve for organizing and/or arranging or aligning, respectively, the reins. They can advantageously assure that the physician is always able to determine which one of the optionally same looking reins he holds in his hand or wants to operate. Hereto, he has only to orientate from which channel the respective rein comes out or leaves, respectively, or into which channel the rein enters. 
     In particular, the channels can serve for avoiding any disorientation or tangling, entangling, knotting or interloping, respectively, etc. of the reins with each other. 
     Furthermore, reins serving for the same or a common purpose during operation can be combined in the respective channels. Thus, reins which all have to be operated for effecting a certain behavior of the implant or the catheter can be guided through one channel. Reins which have to be operated for effecting another behavior of the implant or the catheter can be guided through another channel. Obviously, using the reins facilitates the operation of the implant or of the catheter by the physician. 
     Additionally, reins running to the implant can also be separated from reins running back from the implant. 
     Furthermore, providing the reins in a plurality of channels and their guidance therein can avoid a mutual interaction or interference, respectively, or the risk thereof. With the corresponding arrangement of the reins in separate channels it can, for example, be assured that, by pulling one rein running in a first channel, another rein is not unintendedly operated due to friction or any other interaction of the pulled rein with this other rein. 
     Furthermore, providing a plurality of channels for separately guiding reins can advantageously enable a separation of reins and other means such as, for example, a guiding wire. The function of the reins is thus not impacted or influenced, respectively, by further means and functions of the catheter, but—and this is not less advantageous—also vice-versa; i. e., it can also advantageously be avoided that the further means such as a guiding wire is impacted or influenced, respectively, by the presence or operation of the reins of the catheter. 
     Providing a plurality of channels for separately guiding reins can thus advantageously increase the precision during operation of the reins and thus the use of the catheter or of the implant. 
     In a further preferred embodiment of the present invention, a catheter comprising at least one passage means for letting pass one or more reins is proposed. As proposed in another preferred embodiment, the reins can serve for influencing the expansion and/or unfolding of the implant by changing a tension or stress, respectively, that is applied on the implant by the rein. 
     According to the invention, letting pass is also understood as passing or guiding through. A passage means can be a passage opening, an eye or loop, respectively, a deflecting or diverting section or the like. 
     According to the invention, a rein can comprise a polymer, a metal or a biological fiber material or can consist thereof. The rein or the reins can be absorbable. 
     According to the invention, a tension or a stress, respectively, which is applied to the implant by the rein, is also understood as a strain or in general any effect of the rein on the implant. 
     Whenever the present application refers to a rein, there can be meant more than one rein, for example, two, three, four, five or more reins. 
     The reins can also be provided functionally separated from the catheter. 
     The catheter can comprise an inner guiding means for the at least one rein. 
     In a preferred embodiment, the reins can leave or get out of the catheter at one side and/or at one end of the catheter through one or more passage means (especially, when those are designed as passage openings). Those passage means can be present in or on one or several planes perpendicular to the longitudinal axis of the catheter. 
     The catheter can comprise a device for cutting or tearing through the reins. 
     The implant can be a stent, in particular a valve supporting stent, in particular a cardiac valve supporting stent. 
     According to the invention, an implant, in particular a stent, is proposed, which comprises at least one means which is provided or prepared with the means of a catheter as defined above for controlling the expansion and/or unfolding of the implant from a first diameter to a second diameter and/or the return back from the second diameter to the first diameter in order to control the change of the diameter. 
     The advantages achievable herewith correspond at least to those of the catheter according to the invention. In order to avoid repetitions, it is therefore referred to the discussion thereof. 
     In a preferred embodiment, the implant comprises at least one guiding means which is prepared and suited for guiding at least one rein by which at least one section of the implant is expandable and/or decollapsible or unfoldable, respectively, from the first diameter to the second diameter and/or is returnable back from the second diameter to the first diameter by changing the tension or stress, respectively, or the strain applied to the rein. 
     The implant can be self-expanding, for example, it can be formed from or with a memory material, in particular nitinol, or materials which comprise nitinol. However, the implant can also be partly self-expanding, partly expandable by the use of an expanding means. The implant can exclusively be non-self-expanding. The implant can be foldable; the implant can be non-foldable. 
     The implant can comprise a biocompatible material, in particular a biocompatible stainless steel. The material can be bio-absorbable. 
     The implant can be designed with or without a means for encompassing or sandwiching parts of native valve sections (in particular heart valve leaflets). In particular, the implant can be designed with or without sections rising up or lowering down due to temperature and memory effect. 
     The one or several guiding means of the implant can be designed in form of guiding holes, guiding rings, eyes or loops, respectively, hooks or, generally spoken, guiding structures. They confer guidance to the rein which can be understood in the sense of directing the rein in one direction. According to the invention, guidance can also be understood such that the rein experiences stabilization along its extension. Thereby, the rein can be guided or directed, respectively, by the guiding means from an interior of the implant or stent, in particular from the catheter, to the implant structure (in particular to the exterior of the implant). The guiding means of the implant can be symmetrical (in particular circular, oval or square) or asymmetrical. The guiding means can be located on one plane, on several planes or on a spiral plane of the implant. Several guiding means can be designed equally or can be present in at least two different designs. 
     The implant or the stent can comprise a circular guiding means. The said can be designed in form of a channel which is, relative to the implant, open or closed to the outside, to the top or to the bottom. The guiding means can be closed or open and can have a symmetrical or asymmetrical form. The guiding means can be designed in form of a grid structure, a meander structure, a sinus wave structure, in particular one comprising 18 wave tips along a periphery, or the like. The guiding means can have a structure without a grid and/or without a meander and/or without a sinus wave structure. However, it can also comprise a sinus wave structure having a number of wave tips other than 18. 
     The implant can be a valve supporting stent and made from steel such as described in the patents U.S. Pat. Nos. 5,411,552, 5,840,081 and 6,168,614 B1 by Andersen et al. The stent can, however, also be a valve supporting self-expanding stent according to the disclosure of U.S. Pat. No. 7,018,406 B2 by Seguin et al. or of US 2005/0075731 A1 by Artof et al. The contents of the afore-mentioned documents are by way of reference herewith also subject-matter of the present invention or application, respectively. This particularly applies for material and (part) geometries of the implants and stents disclosed therein. 
     The reins can be guided or directed, respectively, along an interior of the catheter and can leave or get out of the catheter through the passage means. Then, the reins can be guided through the guiding units at or on the implant. The reins can be guided along a periphery or parts of a periphery in the guiding unit along the circumference of the implant. Then, the reins are guided back from outside through the passage means to the interior of the catheter. The reins can leave the catheter at its end proximal to the surgeon. The reins can leave the catheter at its end distal to the surgeon. The effect and in particular the strain of the reins and thus the controlled unfolding and the re-folding or reduction in the diameter of the stent can be controlled by means of a controlling means. 
     A rein can leave the catheter via a passage means arranged at the catheter and can be guided back into the catheter via the same passage means or via another passage means on the same or on another plane. 
     The reins can leave the catheter with their both ends. 
     The reins can leave the catheter with one end and can be connected to the catheter with the other end. 
     After cutting or tearing through or disengaging or notching, respectively, or by using any other kind of detaching or loosening the reins, the reins can be pulled back from the implant or stent and removed. 
     The reins can be cut or torn through by means of a device in the catheter, a device inside or outside the catheter (in particular a knife, a pair of scissors, by means of electrical voltage, by means of heat). A suited device can be arranged at or on the catheter. 
     With little or without any tension of the reins, the stent is unfolded or expanded. With tension being present, the stent is reduced in its diameter or is partly or completely re-folded. 
     According to the invention, a set is proposed which comprises at least one implant according to the invention, in particular a stent, and at least one catheter according to the invention as defined herein-above. 
     The advantages achievable therewith correspond to at least those of the catheter according to the invention. In order to avoid repetitions, it is therefore referred to the discussion thereof. 
     In a preferred embodiment of the set, the catheter is arranged in the center or substantially in the center of a cross-section or of any cross-section of the implant. 
     This center or central arrangement can relate to a state of use. It can relate to a non-unfolded or non-expanded state. It can, however, also relate to a completely expanded or unfolded state. 
     Furthermore, the state of use can be a state during positioning the implant—in particular during its rotation around a rotation center thereof—in order to precisely form the desired positional relation between the implant and the anatomic site at which the implant shall be implanted or come to rest in the body. 
     Arranging the catheter in the center of the implant can involve several advantages wherein a uniformly expanding of the implant is among those. Furthermore, with a centralized catheter, the implant can be controlled and positioned in a better way. The following example may point this out: In the case of a heart valve prosthesis as implant, it can be necessary to align or orientate, respectively, it relative to the commissures of the aortic root during the insertion of the prosthesis (the implant) supported by the catheter in such a way that the orientation thereof and the orientation of the valve leaflets arranged at the prosthesis are concerted or coordinated, respectively. For this purpose, the physician rotates the catheter around its longitudinal axis and, with a centrally arranged catheter, this rotation brings the heart valve prosthesis into a desired position relative to its orientation in its rotational direction, too. If the catheter is thereby not arranged in the center of the rotational-symmetrically constructed heart valve prosthesis, the heart valve prosthesis experiences a displacement in a radial or lateral direction. This displacement not only complicates achieving the desired orientation in the rotational direction, but also effects an undesired force and stress of circumjacent structures such as of the aortic root, of an already inserted receiving means for receiving and anchoring the prosthesis and the like. Centralizing the catheter in the center of the implant can advantageously counteract this. The relative relation between the catheter and the implant can remain unchanged. The occurrence of undesired displacements and forces can advantageously be avoided. 
     Centralizing the catheter in the center of the implant or the arrangement thereof in the center of the implant, respectively, can advantageously be used for checking the valve function with a catheter still being connected to the implant. The valve leaflets can unfold and close for a functional check without being hindered by the centrally arranged catheter; however, this would not be possible if the catheter would have been arranged at the edge, relative to a cross-section of the heart valve prosthesis. A position of the catheter other than the central position could result in a non-uniform opening and closing of the valve leaflets and complicate a functional check, falsify or distort, respectively, the result thereof or make it impossible. Such a functional check with a catheter still being connected to the heart valve is, however, of great importance and of great utility, because a revision or a re-positioning of the valve shall be possible when an unsatisfying position has been determined. 
     A central position of the catheter, relative to the cross-section of the implant, can also be advantageous in a folded or non-expanded state of the implant, because this position can allow a simplification of folding, crimping or the like of the implant. Thereby, the space requirement can advantageously be reduced, a damage of the implant or sections thereof (such as, in one embodiment, valve leaflets) can advantageously be avoided, etc. 
     Furthermore, a central position of the catheter, relative to the cross-section of the implant, can furthermore advantageously enable to control the position of the implant in such a way that the implant uniformly contacts the structure into which it shall be inserted at its periphery. Tension or force peaks which can damage the receiving tissue or complicate the insertion process of the implant can thus advantageously be avoided. The risk of damaging the implant (for example, valve leaflets) or injuring tissue can hereby advantageously be diminished. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be illustrated exemplarily by use of the appended figures. Thereby, same or similar structures are denoted by the same reference numerals throughout the figures, wherein: 
       In a schematically simplified view, 
         FIG. 1  shows a catheter according to the invention which comprises guiding units; 
         FIG. 2  shows the arrangement of  FIG. 1 ; 
         FIG. 3  shows the arrangement of  FIG. 1 ; 
         FIG. 4  shows the arrangement of  FIG. 1 ; 
         FIG. 5  shows an exemplarily run or extension, respectively, of three reins each about ⅓ of the periphery of the stent; 
         FIG. 6  shows the run or extension, respectively, of the reins along the complete periphery of the stent; 
         FIG. 7  shows the catheter of  FIG. 5 ; 
         FIG. 8  shows the catheter of  FIG. 6  comprising the stent of  FIG. 7 ; 
         FIG. 9  shows an expandable stent which is reducible in its diameter again by the use of a means; 
         FIG. 10  shows the stent of  FIG. 9 ; 
         FIG. 11  shows tensioned reins and a reduced diameter of the stent; 
         FIG. 12  shows a stent in the representation of  FIG. 9 ; 
         FIG. 13  shows a stent in the representation of  FIG. 10 ; 
         FIG. 14  shows another embodiment in which the reins are guided around the stent in a spiral form; 
         FIG. 15  shows the rein which is tensioned or stressed, respectively, on both ends, wherein the diameter of the spirally guided rein has been reduced; 
         FIG. 16  shows the state of the rein of  FIG. 15  about or around a stent; and 
         FIG. 17  shows a catheter according to the invention having a cross-section comprising a plurality of lumina. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a catheter  1  comprising a rein  2  which enters into the catheter  1  in the direction of a longitudinal axis L of the catheter  1  and leaves or gets out through passage means  4   a ,  4   b  and  4   c , which can also serve for guiding the rein  2  which can, for example, be designed as a thread, on one or several planes or sections of the catheter  1 . The passage means  4  can be symmetrical or asymmetrical. They can be designed round ( 4   b ), oval ( 4   a ), square ( 4   e ) or in any other suited form. The rein  2  which in the example of  FIG. 1  enters through a longitudinal opening  5  into the catheter  1 , can form a closed loop after leaving or emerging the passage means  4   a , wherein the other end of the closed loop re-enters the catheter  1  at or through the same passage means  4   a  which hereby serves as an entry means and as an exit means at the same time, and leaves the catheter  1 , for example, through the longitudinal opening  5  of the catheter  1 . 
     Between the tip (at the top of  FIG. 1 ) and the longitudinal opening  5  there is located a void  9  of the catheter  1  through which the rein or reins  2  can pass. The void  9  can extend at least from the longitudinal opening  5  to the (in  FIG. 1 ) uppermost passage opening  4   a.    
     Independent of any other feature, i. e., without having to comprise any other feature in combination, the catheter  1  can comprise a mechanically enforced or reinforced section, in particular in a tip area of the catheter and in particular in a section which also comprises at least one of the passage means. 
       FIG. 2  shows the arrangement of  FIG. 1 , wherein the rein  2  has been cut or torn through and can now be pulled back from a stent not shown here and out of the catheter  1 . 
       FIG. 3  shows in turn the arrangement of  FIG. 1  wherein the rein  2  is guided in form of a curve  6  around the stent (not shown) and returns through the same passage means  4   a  into the catheter  1 . The rein  2  has no or only little tension at which the stent can be unfolded. 
       FIG. 4  shows in turn the arrangement of  FIG. 1  and in particular that of  FIG. 3 , wherein the rein  2  is tensioned or stressed in  FIG. 4 . The diameter of the stent (not shown) has been reduced again due to the effect of the curve  6 . In case of a foldable stent, the stent is partly or completely re-folded. 
       FIG. 5  shows an exemplary run or extension of three reins  2   a ,  2   b  and  2   c  each around ⅓ of the periphery of the stent. Each of these reins leaves the catheter through a passage means  4 ′,  4 ″ or  4 ′″ and returns back through a different passage means. 
       FIG. 6  shows the run or extension of the reins  2   a ,  2   b  and  2   c  around the complete periphery. Each of the reins emerges from the catheter  1  out of a passage means  4 ′,  4 ″ or  4 ′″ and re-enters into the catheter  1  through the same passage means. 
       FIG. 7  shows the catheter  1  of  FIG. 5 . The reins  2   a ,  2   b  and  2   c  leave the catheter  1  and are guided at around ⅓ of the periphery in a guiding means  11  of the stent  13  (which is hereby exemplified by a half-open channel in form of a C). 
       FIG. 8  shows the catheter  11  of  FIG. 6  comprising the stent  13  of  FIG. 7 . The reins  2   a ,  2   b  and  2   c  leave the catheter  1  and are each guided back through the guiding means  11  along the complete circumference or the complete periphery of the stent  13  to the same passage means  11  at or on the catheter  1 . 
       FIG. 9  shows an expandable stent  13  which is reducable in its diameter (in a plane perpendicular to a longitudinal axis of the stent which substantially corresponds to a laminar flow direction of the blood in an unbent or uncurved, respectively, vessel into which the stent has been inserted; the longitudinal direction also corresponds to the direction of the largest spatial extension of the stent before its unfolding outside the patient&#39;s body as well as after its unfolding in a comparable linear vessel section) again by the use of a means according to the invention which is not shown here. This stent  13  comprises two circular guiding means  11  each in form of a channel half-open to the outside—that can also be open to the stent—and two passage means  10  in form of round passages (thereby, the passage means  10  can also in any embodiment and independent of any other feature be designed non-round and can be present alone, in pairs, in a threesome or in a multi-some). Furthermore, the stent  13  can also comprise a number of guiding means  11  other than two, for example, one, three, four or more. The guiding means  11  can be arranged circularly, they can, however, also be provided in a non-circular manner. The guiding means  11  can be formed integrally with the stent, they can, however, also be fabricated separately. The passage means  10  can likewise be formed integrally with the stent or likewise be fabricated separately. The guiding means  11  can be designed in wave form, they can, however, also be fabricated in any other form, in particular in a non-wavy form. 
     The passage means  10  are arranged in sections of rods  12 . They can be arranged at opposite ends of the rods  12 , but also in every other section, for example, in a central area or section and not at the end of the rods. They can furthermore be arranged at a position of the stent  13  other than in or at the rods  12 . Reins not shown here can be guided from an interior of the stent  13  through the passage means  10  to the outside and back again. 
     As an example of an implant, the stent  13  can comprise an arbitrary number of rods  12  which are all designed in the same way or have at least two different designs. The rods  12  can thereby be spaced apart from each other with the same distance. They can, however, also be arranged with at least two different distances from each other, respectively. The rods  12  can indeed comprise the passage openings  10 , the latter can, however, also be provided separately from the rods  12 . Likewise, the rods  12  can have openings, they can, however, also be designed without any passage openings. The stent  13  can be designed having rods which do not have any passage openings  10 . The stent can further comprise at least one rod having passage openings and at least one rod not having any passage openings. The stent can comprise at least one rod which does not have any passage openings at all. The stent can comprise at least one rod which is arranged in or at the stent in a manner in which it is inclined to the longitudinal direction of the stent. The rods  12  can thereby extend in a manner in which they are bent or curved at both ends to the outside. Regardless of any other features, they can, however, extend such that they are not or at least not at both ends curved or bent to the outside. The rods  12  can be connected with or at their both ends to a wavy structure of the stent. Regardless of any other features, they can, however, not or at least not at both ends be connected to wavy structures. 
     Independent of any other feature, the stent  13  can be manufactured from flat material, for example, a material which has been cut with a laser, wherein, e.g., after having designed a pattern in the flat material, the material is reformed into a tube (optionally by connecting, such as welding, longitudinal sides of the former flat material lane or web, respectively). However, the stent  13  can also be fabricated from a tubular material directly. 
       FIG. 10  shows the stent  13  of  FIG. 9 . Two reins  2  have been guided around the stent  13  and return back to the catheter  1  through the same guiding means  10 , respectively. The reins  2  exert no or only a small tension or stress on the stent  13  and the stent  13  is unfolded. 
     In  FIG. 11 , the reins  2  are tensioned or stressed. The diameter of the stent  13  has been reduced. The stent  13  is re-folded at a larger extent. The reins  2  are guided in the guiding means  11  of the stent  13 . 
       FIG. 12  and  FIG. 13  show a stent  13  in a representation corresponding to the representation of  FIG. 9  and  FIG. 10 , respectively. Thereby,  FIG. 9  shows the stent  13  in an expanded state,  FIG. 10  shows the stent  13  with a reduced diameter again. The stent shown in  FIG. 9  and  FIG. 10  can thereby correspond to any stent known (with or without having valves). The stent  13  can in particular correspond to any unfoldable stent known. 
     In addition, in a schematically simplified manner,  FIG. 12  shows a control unit for unfolding or expanding and in turn folding or reducing the stent  13  in its diameter in a controlled manner. 
       FIG. 14  shows that the reins  2  can also be guided in a spiral form around the stent  13 . Here, only one rein  2  is shown which is guided in the interior of the stent  13  to the section in the front thereof. Then, the rein  2  is guided over the stent  13  at the outside and re-enters the catheter  1  (not shown here) again. The rein  2  is not or only a little tensioned or stressed and the stent (not shown here) is unfolded. 
     In  FIG. 15 , the rein  2  is pulled up at both ends in the arrow direction and the diameter of the curve  6  of the spirally guided rein  2  has been reduced. 
       FIG. 16  shows the state of the rein  2  of  FIG. 15 . The rein  2  (which is here also referred to as a thread) has been tensioned or stressed and the stent  13  has been folded or collapsed by use of the spirally guided rein  2 . 
       FIG. 17  shows a catheter  1  according to the invention comprising a plurality of lumina or channels  23  for guiding through reins (not shown in  FIG. 17 ) in a cross-section thereof. These channels  23  for the reins are designated by the letters B, C, D, E, F, G and H. 
     The lumina can be suited and prepared for guiding through reins for using the catheter. 
     The catheter  1  has a further lumen  25  in its center which is designated by the letter A and which is, in the embodiment shown, provided for receiving a means, such as a guiding wire, which is likewise not shown in  FIG. 17 . 
     The further lumen  25  which is shown in the center of the cross-section of catheter  1  in  FIG. 17  is not limited to this arrangement. (One or more) lumen/lumina or channel(s) can also be arranged at the edge of the cross-section; two of them can be opposite to each other due to handling reasons, etc. Moreover, the catheter can comprise more than one lumen  25  for one or several further means, respectively. 
     The further means  25  can be a means other than a rein and/or not assuming a function in changing the diameter of the implant. 
     The further means  25  can be a means for cutting or tearing through the reins.