Patent Publication Number: US-8123794-B2

Title: Intraluminal support frame

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 11/314,661, filed on Dec. 20, 2005 and now patented as U.S. Pat. No. 7,544,205, which claims priority to U.S. Provisional Application Ser. No. 60/593,195, filed on Dec. 20, 2004. The entire disclosure of each of these related applications is hereby incorporated by reference into this disclosure. 
    
    
     FIELD 
     The invention relates generally to the field of medical devices. More particularly, the invention relates to intraluminal support frames and intraluminal medical devices that include an intraluminal support frame. 
     BACKGROUND 
     Various types of disease conditions present clinical situations in which a vessel of a patient needs to be artificially supported to maintain an open passageway through which fluids, such as blood, can flow. For example, blood flow through an artery can be impeded due to a build-up of cholesterol on the interior wall of the vessel. Also, vessel walls can be weakened by a variety of conditions, such of aneurysms. 
     Intraluminal support frames provide an artificial mechanism to support a body vessel. The prior art provides many examples of intraluminal support frames, including an array of cardiovascular stents. Many prior art support frames are tubular-shaped members that are placed in the lumen of the vessel and, once deployed, exert a radially-outward directed force onto the vessel wall to provide the desired support. Support frames can also provide a base architecture onto which additional functionality can be built. For example, graft members and valve members can be attached to a support frame to provide graft and valve devices, respectively. The support frame in these types of devices can serve simply to provide the base architecture, or to both provide the base architecture and a vessel support mechanism as described above. 
     Intraluminal support frames are typically positioned at a point of treatment in a body vessel by navigation through the vessel, and possibly other connected vessels, until the point of treatment is reached. This navigation requires that the support frame be able to move axially through the vessel(s) while still maintaining the ability to exert an outward force on the interior wall once deployed. Accordingly, intraluminal support frames typically have radially unexpanded and expanded configurations. In the unexpanded configuration, the support frame has a relatively small diameter that allows it to be moved axially through the vessel. In the expanded configuration, the support frame has a relatively large diameter that allows it to engage an interior wall of the body vessel and exert a radially outward directed force on the interior wall, thereby providing the desired support to the vessel. 
     Once the support frame is navigated to a desired point of treatment in a body vessel, the support frame is deployed by allowing it to assume its expanded diameter. During expansion from the radially unexpanded configuration to the radially expanded configuration, intraluminal support frames can exhibit a degree of foreshortening, which can affect the accuracy of placement of the support frame. Indeed, the foreshortening effect is frequently referred to as a “jumping” of the support frame during deployment. Foreshortening is particularly evident in self-expandable support frames, which do not require an application of force to achieve the expanded configuration. Foreshortening of support frames in a medical device that includes an additional component or components, such as a graft member or a valve member, could have an effect on the functioning of the component(s). 
     SUMMARY OF EXEMPLARY EMBODIMENTS 
     Intraluminal support frames and medical devices that include an intraluminal support frame are described. Support frames according to the invention have a ring architecture and at least one connector strut that connects three or more rings to each other. 
     An intraluminal support frame according to one exemplary embodiment comprises a plurality of ring structures and first and second sets of connector segments. Each of the first set of connector segments joins an adjacent pair of the plurality of ring structures, and each of the second set of connector segments joins at least three ring structures of the plurality of ring structures. 
     Medical devices that include a support frame are also described. A medical device according to one exemplary embodiment comprises a support frame according to the invention and an attached graft member. 
     A medical device according to another exemplary embodiment comprises a prosthetic valve for regulating the flow of fluid through a body vessel. In this embodiment, the medical device comprises a support frame and an attached valve member. 
     Additional understanding of the invention can be gained by reference to the attached drawings and the detailed description presented below, each of which relate to exemplary embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flat pattern view of an intraluminal support frame according to a first exemplary embodiment shown in an expanded configuration. 
         FIG. 2  is a flat pattern view of the support frame illustrated in  FIG. 1  shown in an unexpanded configuration. 
         FIG. 3  is a flat pattern view of an intraluminal support frame according to a second exemplary embodiment shown in an expanded configuration. 
         FIG. 4  is a perspective view of a medical device according to a third exemplary embodiment. 
         FIG. 5  is an elevational view of a medical device according to a fourth exemplary embodiment. 
         FIG. 6  is an end view of the medical device illustrated in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The following description of exemplary embodiments provides illustrative examples of the invention. The embodiments discussed herein are merely exemplary in nature and are not intended to limit the scope of the invention, or its protection, in any manner. Rather, the description of these exemplary embodiments serves to enable a person of ordinary skill in the relevant art to practice the invention. 
       FIGS. 1 and 2  illustrate an intraluminal support frame  10  according to a first exemplary embodiment of the invention. Each of  FIGS. 1 and 2  are flat pattern views of the support frame  10 . Thus, in use, the flat pattern illustrated in the figures is circularized along a lengthwise axis to form a cylindrical support frame that defines an interior passageway. The flat pattern views are presented simply to facilitate understanding of the architecture of the support frame. It is expressly understood that support frames in accordance with the invention do not need to be fabricated by circularizing a flat piece to form a cylindrical member. While this certainly is an acceptable method of fabrication for support frames according to the invention, any suitable method can be used. For example, an appropriate pattern can be cut from a tubular member to form a desirable pattern. 
     The support frame  10  comprises a plurality of ring structures  12  interconnected by first  14  and second  16  sets of connector segments. 
     Each ring structure  12  is a substantially circular ring comprising an endless undulating pattern. In the illustrated embodiment, the undulating pattern comprises a serpentine pattern  18 . Any suitable ring structure with the desired undulating pattern can be used, including rings formed by bending a wire in a zig-zag pattern and joining the ends. Alternatively, a ring structure can be formed by cutting a suitable pattern from a solid tube of material. Examples of suitable ring structures are described in U.S. Pat. Nos. 4,580,568 to Gianturco for PERCUTANEOUS ENDOVASCULAR STENT AND METHOD FOR INSERTION THEREOF and 6,786,922 to Schaeffer for STENT WITH RING ARCHITECTURE AND AXIALLY DISPLACED CONNECTOR SEGMENTS, each of which is hereby incorporated in its entirety into this disclosure for the purpose of describing suitable ring structures for use with the invention. 
     The support frame  10  can include any suitable number of ring structures  12 . The specific number of ring structures  12  included in a particular support frame according to the invention will depend on several factors, including the anticipated axial length of a treatment site at which the support frame may be deployed. The support frame illustrated in  FIGS. 1 and 2  includes sixteen ring structures. As a minimum, and based on the interrelationship between the sets  14 ,  16  of connector segments and the ring structures  12 , a support frame according to the invention includes at least three ring structures. 
     The first set  14  of connector segments join adjacent ring structures  12 . As best illustrated in  FIG. 1 , an individual connector segment  20  of this set  14  extends between two adjacent ring structures  12 . The connector segment  20  is advantageously terminated at each of the adjacent ring structures  12  to enhance the overall flexibility of the support frame  10 . 
     The first set  14  of connector segments can include any suitable number of individual connector segments  20 . The specific number chosen for any particular support frame according to the invention will depend on several factors, including the desired flexibility of the support frame. Also, as best illustrated in  FIG. 1 , first  22  and second  24  adjacent pairs of ring structures  12  can have different numbers of first set  14  connector segments interconnecting the respective pairs of ring structures  12 . In the illustrated embodiment, four (4) first set  14  connector segments interconnect the ring structures  12  of the first pair  22  while six (6) first set  14  connector segments interconnect the ring structures  12  of the second pair  24 . This arrangement is considered advantageous at least because it allows for localized flexibility along the length of the support frame  10 . 
     Also, as best illustrated in  FIG. 1 , the first set  14  connector segments joining the first pair  22  of ring structures  12  are advantageously disposed out of phase with the first set  14  connector segments joining the adjacent second pair  24  of ring structures  12 . This arrangement enhances the overall stability of the support frame  10 . As used herein with reference to connector segments, the term “out of phase” describes a spatial relationship between connector segments in which the connector segments lie on different lengthwise axes. 
     The second set  16  of connector segments join three or more adjacent ring structures  12 . In the embodiment illustrated in  FIGS. 1 and 2 , individual connector segments  26  of the second set  16  of connector segments join all of the ring structures  12  in the support frame  10 . The individual connector segments  26  of the second set  16  provide longitudinal stability to the support frame  10  and provide desirable foreshortening characteristics for the support frame  10 . 
     The second set  16  of connector segments can include any suitable number of individual connector segments  26 . The specific number chosen for any particular support frame according to the invention will depend on several factors, including the desired longitudinal stability and flexibility of the support frame. In the embodiment illustrated in  FIGS. 1 and 2 , the second set  16  includes two individual connector segments  26  (note that, as a feature of the flat pattern nature of the drawings, one of the connector segments is split lengthwise). No matter the number chosen, the individual connector segments  26  of the second set  16  can be relatively positioned in any suitable manner. In the embodiment illustrated in  FIGS. 1 and 2 , the individual connector segments  26  of the second set  16  are diametrically opposed from each other in the cylindrical form of the support frame  10 . Other relative positioning of the individual connector segments  26  can be used, including localization of multiple connector segments  26  on one side of the support frame  10 . It is also noted that the second set  16  of connector segments can comprise a single individual connector segment  26 . 
     In the embodiment illustrated in  FIGS. 1 and 2 , at least two peaks  28  of the undulating pattern  18  of a ring structure  12  are disposed between an individual connector segment  26  of the second set  16  of connector segments and each individual connector segment  20  of the first set  14  of connector segments. More or fewer separating peaks  28  can be employed, but a minimum of two is considered advantageous. Also, different pairs of adjacent ring structures  12  can have different numbers of separating peaks. For example, in the embodiment illustrated in  FIGS. 1 and 2 , three separating peaks  30  are disposed between the first set  14  and second set  16  connector segments that join a first pair  22  of adjacent ring structures  12 , while two separating peaks  32  are disposed between the first set  14  and second set  16  connector segments that join a second pair  24  of adjacent ring structures  12 . 
     The support frame  10  is an expandable support frame having radially unexpanded and radially expanded configurations. As such, the support frame  10  can be a self-expandable support frame, such as one fabricated from a shape memory material such as nickel-titanium alloy, a balloon expandable support frame or any other type of expandable frame.  FIG. 1  illustrates the support frame  10  in its radially expanded configuration and  FIG. 2  illustrates the support frame  10  in its radially unexpanded configuration. 
     The support frame  10  can be fabricated from any suitable material. The material chosen for any particular support frame according to the invention need only be biocompatible or able to be made biocompatible. Examples of suitable materials include shape memory alloys, such as nickel-titanium alloys, and stainless steel. The ring members  12  and sets  14 ,  16  of connector segments can be fabricated from the same or different materials using conventional techniques, including winding and braiding techniques as well as laser-cutting techniques. 
       FIG. 3  illustrates a support frame  110  according to a second exemplary embodiment.  FIG. 3  is a flat pattern view of the support frame  110  and illustrates the support frame  110  in a radially expanded configuration. 
     The support frame  110  according this embodiment is similar to the support frame  10  illustrated in  FIGS. 1 and 2 , except as described below. Accordingly, similar features and/or components are labeled with similar reference numbers as those in  FIGS. 1 and 2 , increased by one hundred. 
     The support frame  110  comprises a plurality of ring structures  112  interconnected by first  114  and second  116  sets of connector segments. Each ring structure  112  has an endless undulating pattern  118 . Individual connector segments  120  of the first set of connector segments  114  join a pair of adjacent ring structures  112 . Individual connector segments  126  of the second set of connector segments  116  join three or more adjacent ring structures  112 . 
     In this embodiment, each of the individual connector segments  126  of the second set  116  of connector segments joins fewer than all of the ring structures  112  that form the support frame  110 . Advantageously, each of the individual connector segments  126  of the second set  116  of connector segments can join less than one half of the ring structures  112  that form the support frame  110 . Alternatively, each of the individual connector segments  126  of the second set  116  of connector segments can join fewer than one third of the ring structures  112  that form the support frame, or any other suitable number of ring structures  112  that is less than the total number of ring structures  112  in the support frame  110 . 
     This arrangement of the second set  116  of connector segments forms first  150  and second  160  regions on the support frame  110 . The first region  150  includes connector segments from both sets  114 ,  116 , and the second region  160  includes only connector segments from the first set  114 . As a result, the first region  150  has enhanced longitudinal stability compared to the second region  160 , and exhibits enhanced foreshortening characteristics over those of the second region  160 . This differential architecture may be desirable in a variety of applications, including medical devices with functional members, such as graft members and/or valve members, attached to a support frame. An example of such a medical device is described below. Also, this arrangement can be advantageous in applications in which a localization of foreshortening is desired along a portion of the length of a medical device. 
       FIG. 4  illustrates a medical device  200  according to an exemplary embodiment. The medical device  200  includes a support frame  210  according to the invention and an attached graft member  270 . 
     In the illustrated embodiment, the support frame  210  is the support frame  10  illustrated in  FIGS. 1 and 2 . Accordingly, similar features and/or components are labeled with similar reference numbers as those in  FIGS. 1 and 2 , increased by two hundred. 
     The support frame  210  comprises a plurality of ring structures  212  interconnected by first  214  and second  216  sets of connector segments. Each ring structure  212  has an endless undulating pattern  218 . Individual connector segments  220  of the first set  214  of connector segments join a pair of adjacent ring structures  212 . Individual connector segments  226  of the second set  216  of connector segments join all ring structures  212  of the support frame  210 . 
     While the illustrated example includes a specific support frame  210  according to the invention, it is understood that the medical device  200  can include any support frame according to the invention. 
     The graft member  270  is attached to the support frame  210  and is disposed around the support frame  210  and along its entire length. It is understood that the graft member  270  can be disposed around any suitable portion of the support frame  210  and along any suitable length of the support frame  210 . Also, the graft member  270  can be disposed on the exterior, the interior, or both the exterior and interior of the support frame  210 . 
     The graft member  270  can be formed of any suitable material, and need only be biocompatible or be able to be made biocompatible. The medical device arts include several examples of suitable materials for use as or in the graft member. The specific material chosen for the graft member in a particular medical device according to the invention will depend on several factors, including the anticipated point of treatment and/or vessel type at which the medical device will be used. Examples of suitable materials include expanded polytetrafluoroethylene (ePTFF), polyurethane, and bioremodellable materials such as, extracellular matrix (ECM) materials, including small intestine submucosa (SIS) and other ECM&#39;s. Other bioremodellable materials can be used as well. Tissues and other natural materials can also be used, including processed versions of natural materials, including fixed tissue. 
     The graft member  270  is attached to the support frame  210  by attachment elements  280 . Any suitable type and number of attachment elements  280  can be used, including sutures, staples, clips, adhesives, and the like. As illustrated in  FIG. 5 , the graft member  270  is advantageously attached to the support frame  210  at one or more points along the individual connector segments  226  of the second set  216  of connector segments  216 . It is expressly understood, though, that the attachment elements  280  can be positioned at any point on the medical device  200  and support frame  210 . 
     The medical device  200  is useful as a supported graft, such as a stent graft, and can be used in a variety of applications, including vessel repair and aneurysm exclusion. 
       FIGS. 5 and 6  illustrate a medical device  300  according to an exemplary embodiment. The medical device  300  according to this embodiment is a prosthetic valve that can be used to regulate fluid flow through a body vessel. The medical device  300  can be used in a blood vessel, such as a vein, or in any other suitable body vessel. Also, the medical device  300  can be used in and/or with a body organ, such as a heart, to provide a valve for the organ and/or augment, replace, or otherwise treat a natural valve associated with the organ. The medical device  300  includes a support frame  310  according to the invention and an attached valve member  390 . 
     In the illustrated embodiment, the support frame  310  comprises a plurality of ring structures  312  interconnected by first  314  and second  316  sets of connector segments. Each of the ring structures  312  has an endless undulating pattern  318 . Individual connector segments  320  of the first set  314  of connector segments join an adjacent pair of ring structures  312 , while individual connector segments  326  of the second set of connector segments  316  join three or more adjacent ring structures  312 . The support frame  310  includes first  350  and second  360  regions, similar to the support frame illustrated in  FIGS. 3 and 4 . The first region  350  includes connector segments from both the first  314  and second sets  316  of connector segments, while the second region  360  includes only connector segments from the first set  314  of connector segments. 
     The valve member  390  is attached to the support frame  310  at the first region and advantageously along a portion of the length of one or more connector segments  326  of the second set  316  of connector segments. Attachment elements  392  are used to connect the graft member  390  to the support frame  310 . Any suitable type and number of attachment elements, including sutures, staples, clips, adhesives and the like, can be used. 
     As best illustrated in  FIG. 7 , the valve member  390  is attached to the support frame  310  in a manner that allows the valve member  390  to form a valve opening  394  that alternately opens and closes to allow and substantially prevent, respectively, fluid flow through the medical device  300 . 
     The valve member  390  can comprise a single member, such as a tubular member, or multiple members, such as multiple valve leaflets. The valve member  290  need only be attached to the support frame in a manner that forms the desired valve opening  394 . 
     Any suitable material can be used for the valve member  390 , including natural and synthetic materials. The specific material chosen for a particular medical device according to the invention will depend on several factors, including the intended point of treatment and vessel type at which the medical device will be used and the intended function of the medical device. Examples of suitable materials include polymeric materials, such as polyurethane, and bioremodellable materials, such as SIS and other ECM&#39;s. ECM&#39;s are considered particularly advantageous at least because of their ability to be tolerated in a variety of in vivo environments and their ability to remodel into natural host tissue. Other currently contemplated materials include bovine pericardium and other natural materials. Tissue valves, which comprise preexisting natural valves harvested from animal tissue, such as a heart or other valve-containing or defining tissue, can be used, as can other suitable tissues or sections thereof. Porcine heart valves are considered particularly well-suited tissue valves for use in medical devices according to the invention. Tissues and other natural materials can be used in their natural state or in a processed form, such as a form rendered substantially biologically inert by chemical treatment. For example, a cross-linked ECM, such as cross-linked SIS, can be used. 
     The foregoing detailed description provides exemplary embodiments of the invention and includes the best mode for practicing the invention. The description and illustration of embodiments is intended only to provide examples of the invention, and not to limit the scope of the invention, or its protection, in any manner.