Abstract:
A filtering device with an increased surface area, and method of making and using the same. The present invention comprises a filtering device including an elongate shaft and a filter coupled to the shaft. The filter may include a filter membrane configured to have an increased surface area.

Description:
FIELD OF THE INVENTION 
     The present invention pertains to filtering devices. More particularly, the present invention pertains to embolic protection filtering devices having a filter membrane with an increased surface area. 
     BACKGROUND 
     Heart and vascular disease are major problems in the United States and throughout the world. Conditions such as atherosclerosis result in blood vessels becoming blocked or narrowed. This blockage can result in lack of oxygenation of the heart, which has significant consequences since the heart muscle must be well oxygenated in order to maintain its blood pumping action. 
     Occluded, stenotic, or narrowed blood vessels may be treated with a number of relatively non-invasive medical procedures including percutaneous transluminal angioplasty (PTA), percutaneous transluminal coronary angioplasty (PTCA), and atherectomy. Angioplasty techniques typically involve the use of a balloon catheter. The balloon catheter is advanced over a guidewire such that the balloon is positioned adjacent a stenotic lesion. The balloon is then inflated and the restriction of the vessel is opened. During an atherectomy procedure, the stenotic lesion may be mechanically cut away from the blood vessel wall using an atherectomy catheter. 
     During angioplasty and atherectomy procedures, embolic debris can be separated from the wall of the blood vessel. If this debris enters the circulatory system, it could block other vascular regions including the neural and pulmonary vasculature. During angioplasty procedures, stenotic debris may also break loose due to manipulation of the blood vessel. Because of this debris, a number of devices, termed embolic protection devices, have been developed to filter out this debris. 
     BRIEF SUMMARY 
     The invention provides design, material, manufacturing method, and use alternatives for intravascular filtering devices. In at least some embodiments, these filtering devices include a shaft having an embolic protection filter coupled thereto. The filter may adapted and configured to have an increased surface area or otherwise include other improvements. These and other desirable features are described in greater detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is side view of an example embolic protection filtering device; 
         FIG. 2  is a cross-sectional view of the filtering device through line  2 — 2 ; 
         FIG. 3  is a cross-sectional view of the filtering device through line  3 — 3 ; 
         FIG. 4  is side view of another example embolic protection filtering device; 
         FIG. 5  is a cross-sectional view of the filtering device through line  5 — 5 ; 
         FIG. 6  is a cross-sectional view of the filtering device through line  6 — 6 ; 
         FIG. 7  is a cross-sectional view of the filtering device through line  7 — 7 ; 
         FIG. 8  is a side view of another example embolic protection filtering device; 
         FIG. 9  is a side view of a portion of the filtering device shown in  FIG. 8 ; 
         FIG. 10  is a side view of another example embolic protection filtering device; 
         FIG. 11  is a side view of another configuration of the filtering device shown in  FIG. 10 ; and 
         FIG. 12  is a side view of another example embolic protection filtering device. 
     
    
    
     DETAILED DESCRIPTION 
     The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings illustrate example embodiments of the claimed invention. 
     For a number of reasons, it may be desirable to augment the amount of surface area on a device that can be used for filtering debris.  FIG. 1  is a side view of an example filtering device  10  including a filter  12  having an augmented surface area. This structural feature may improve the functioning of filter  12 , for example, by increasing the amount of debris filter  12  can hold, by contributing to more efficient flow through filter  12 , and by enhancing the strength of filter  12 . It can be appreciated that the desirable structural features of filter  12  may also be described in other ways (as an alternative or in addition to having an augmented surface area) such as having an augmented filtering capability, filtering ability, filtering capacity, and the like. The augmented surface area may also provide filter  12  (and/or filtering device  10 ) with a number of additional desirable features including those described below. 
     In general, filter  12  may be adapted to operate between a first generally collapsed configuration and a second generally expanded configuration for collecting debris in a body lumen. In some embodiments, filter  12  and/or filtering device  10  can be delivered to an appropriate intravascular location, for example “downstream” of an intravascular lesion, using an appropriate filter delivery device. Similarly, filter  12  can be removed from the vasculature at the desired time by an appropriate filter retrieval device. 
     Filter  12  may be coupled to a shaft  14  and may include a filter frame  16  and a filter membrane or fabric  18  coupled to filter frame  16 . Frame  16  may take the form of any one of a number of appropriate shapes and configurations. For example, frame  16  may comprise a generally circular filter mouth or loop, which may define the primary opening for blood to travel into and be filtered by filter  12 . However, essentially any appropriate shape or configuration may be utilized without departing from the spirit of the invention. 
     Frame  16  may be comprised of any appropriate material. For example, frame  16  may be comprised of a “self-expanding” shape-memory material such as nickel-titanium alloy that may be configured to bias filter  12  to be in the second expanded configuration. Alternatively, frame  16  may be comprised of essentially any appropriate metal, metal-alloy, polymer, combinations thereof, and the like including any of the materials described herein. In some embodiments, frame  16  or portions thereof may be doped with, plated with, or otherwise include a radiopaque material. Radiopaque materials are understood to be materials capable of producing a relatively bright image on a fluoroscopy screen or another imaging technique during a medical procedure. This relatively bright image aids the user of device  10  in determining its location. Some examples of radiopaque materials can include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloy, plastic material loaded with a radiopaque filler, and the like. For example, a radiopaque wire disposed about a portion of frame  16 . 
     Filter membrane  18  may be comprised of any appropriate material such as a polymer and may be drilled (for example, formed by known laser techniques) or otherwise include one or more openings  20 . Holes or openings  20  can be sized to allow blood flow therethrough but restrict flow of debris or emboli floating in the body lumen or cavity. In at least some embodiments, filter membrane  18  may be configured to augment the surface area of filter  12  as is described in more detail below. 
     One or more struts  22  may extend between frame  16  and shaft  14 . In some embodiments, struts  22  can be coupled to shaft  14  by a coupling  24 , for example a heat-shrink tube, a crimp fitting, and the like. Alternatively, struts  22  may be coupled to shaft  14  by one or more windings of struts  22  about shaft  14 . In some embodiments, struts  22  may comprise an extension or integral part of frame  16 . Alternatively, struts  22  and frame  16  may comprise two distinct structures that can be attached to one another. 
     Shaft  14  can be made of any suitable materials including metals, metal alloys, polymers, or the like, or combinations or mixtures thereof. Some examples of suitable metals and metal alloys include stainless steel, such as 304v stainless steel; nickel-titanium alloy, such as nitinol, nickel-chromium alloy, nickel-chromium-iron alloy, cobalt alloy, or the like; or other suitable material. Although the embodiment shown in  FIG. 1  illustrates shaft  14  as being a guidewire, shaft  14  is not intended to be limited to being only a guidewire. It can be appreciated that shaft  14  may comprise number of different structures including a catheter (e.g., therapeutic, diagnostic, or guide catheter), endoscopic device, laproscopic device, an embolic protection device, or any other suitable device. In some embodiments, shaft  14  may comprise a tubular filter cartridge. According to this embodiment, filtering device  10  (and/or shaft  14 ) can be configured to be slidable over a guidewire or other suitable medical device. 
     As stated above, filter membrane  18  may be adapted and configured to augment the surface area of filter  12 . Augmenting the surface area of filter  12  may be accomplished in a number of ways. For example, filter membrane  18  may include one or more folds or pleats  26  that increase the surface area where debris may be captured or filtered. The amount of surface area that may be added to filter  12  may depend on the “depth” or amount of folding included with each pleat  26 . Accordingly, the “deeper” the amount of folding included with each pleat  26 , the greater the increasing in surface area. It can be appreciated that alterations to the amount of folding or depth of pleats  26  may vary without departing from the spirit of the invention. 
     In at least some embodiments, pleats  26  may be defined by inward deflections of filter membrane  18 . This configuration may allow filter membrane  18  to expand outwardly toward a bulbous shape when greater amounts of debris are captured. Alternatively, pleats  26  may be defined by one or more longitudinal bonds  28  between filter membrane  18  and shaft  14  as best seen in  FIG. 2 . Bonds  28 , for example, may be disposed adjacent a distal region  30  of filter  12 . Portions of filter membrane  18 , however, may not be bonded to shaft  14  as best seen in  FIG. 3 . The non-bonded portion may be disposed adjacent a proximal region  32  of filter  12 . Although the combination of  FIGS. 1 ,  2  and  3  illustrate one example configuration of filter membrane  18  where bonds  28  are disposed along distal region  30  of filter  12  but not along proximal region  32 , this arrangement is not intended to be limiting. Generally, bonds  28  may be disposed along distal region  30 , along proximal region  32 , along the entire length of filter  12 , or any other suitable combination or arrangement.  FIGS. 2 and 3  also illustrate more clearly that shaft  14  may comprise a tubular filter cartridge that may be slidable over a medical device such as a guidewire  34 . 
       FIG. 4  is another example filtering device  110  that is essentially the same in form and function as device  10 , except that filter  112  include one or more longitudinal fibers  136  (best seen in  FIGS. 5 ,  6 , and  7 ) and that the folds or pleats  126  of filter membrane  118  may be defined by bonds  128  (best seen in  FIGS. 5 ,  6 , and  7 ) between filter membrane  118  and fibers  136 . According to this embodiment, fibers  136  may act as a substrate or bonding surface for filter membrane  118  as well as help define a configuration of filter  112  that has increased surface area. Fibers  136  may also provide filter  112  with other desirable features such as strength, radiopacity, etc. 
     In at least some embodiments, fibers  136  may be attached to and extend distally from filter frame  116 . For example, opposite ends of fibers  136  may be attached to filter frame  116  and shaft  14 . According to this embodiment, the spacing between fibers  136  and shaft  14  gets larger at more proximal filter locations. For example,  FIG. 5  is a cross-sectional view of filter  112  at a relatively distal position, illustrating fibers  136  disposed adjacent shaft  14 .  FIGS. 6 and 7 , which illustrate increasingly more proximal positions along filter  112 , depict increasing radial spacing of fibers  136  from shaft  12 . 
       FIG. 8  is another example filtering device  210  that is essentially the same in form and function as any of the others described herein except that filter  212  includes one or more sinusoidal ribs  238 . In at least some embodiments, sinusoidal ribs  238  may be attached to or disposed adjacent to filter frame  16  and/or filter membrane  18 , and may extend distally along filter  212 . The precise location and length of ribs  238 , however, may vary. In general, ribs  238  may be configured for being disposed along the region of filter  212  that contacts or may contact the interior wall of a blood vessel  240  as shown in  FIG. 9 . This feature may be desirable, for example, because it allows a smaller portion of filter membrane  218  to be “blocked” by contact with blood vessel  240 . Accordingly, the surface area of filter  212  that can be used to collect debris is increased. 
     Another example filtering device  310  is shown in  FIG. 10 . Device  310  is essentially the same in form and function as any of the other devices described herein except that filter  310  includes a distal apex ring member  342  that is slidable along shaft  14 . Accordingly, filter  312  may be able to shift from a first relatively shortened or inverted configuration (as shown in  FIG. 10 ) to a second relatively elongated or everted configuration (as shown in  FIG. 11 ). 
     Shifting between the first and second configurations may be accomplished in a number of ways. For example, filter  312  may be originally placed within a body lumen in the first configuration and then shift to the second configuration as filter  312  becomes filled with debris. According to this embodiment, ring member  342  may frictionally engage shaft  14 . However, when filter  312  becomes sufficiently full, forces exerted on filter  312  (e.g., due to fluid flow within the body lumen) may overcome the frictional force and shift filter  312  to the second configuration. 
     Alternatively, shifting the configuration of filter  312  may be accomplished in another example filtering device  410  by using a shifting member or rod  444  as shown in  FIG. 12 . According to this embodiment, rod  444  may be attached to ring member  342  and extend proximally therefrom. A clinician may then grasp rod  444  and alter the configuration of filter  312  by proximally or distally shifting rod  444 . 
     It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps without exceeding the scope of the invention. The invention&#39;s scope is, of course, defined in the language in which the appended claims are expressed.