Abstract:
A locking element comprising a frame defining a central lumen through which a portion of the elongate member fits; one or more levers extending in the second direction from the frame able to be moved between a locking position and a releasing position; and one or more tabs extending in the first direction from the frame able to be moved by the one or more levers between a locked position and a released position; wherein when the locking element is disposed on an enabling elongate member in a second direction from a second cross section, the one or more tabs prevent the locking element from moving in a first direction beyond a first cross section when disposed in the locked position and do not prevent the locking element from moving in the first direction when disposed in the released position.

Description:
[0001]     This is a continuation of U.S. application Ser. No. 10/302,410, filed Nov. 22, 2002. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention generally pertains to apparatus and methods for deploying and retrieving a medical device from an elongate member. More particularly, the present invention generally pertains to apparatus and methods useful for locking a medical device on an elongate member and subsequently releasing the medical device.  
       SUMMARY OF THE INVENTION  
       [0003]     Embodiments of the invention pertain to a selectively locking element that may be attached to a medical device such as a filter or therapeutic deliver device and may be disposed on an elongate member such as a guidewire. The selectively locking element enables the medical device to be disposed on the elongate member such that it will stay on the elongate member past a transition region. The elongate member should be configured to enable the selectively locking element to lock. This may be done by providing a first region of the elongate member that has a distance to the central longitudinal axis that is less than the distance to the central longitudinal axis of a proximal region in a direction along the central longitudinal axis. A guidewire having a raised region on it would be an example of an elongate member that enables the selectively locking element. The selectively locking element may comprise one or more tabs and corresponding levers, where the tabs have a locked position and a released position and the levers have a corresponding locking position and releasing position. The tabs may be biased to the locked position. When the selectively locking element is moved in a first longitudinal direction over the first region, the tabs may move into the locked position, preventing moving of the selectively locking element back in the second longitudinal direction. A catheter or other object may be used to move the levers to the releasing position, thereby moving the tabs to the released position and allowing movement of the selectively locking element in the second direction. Various centering elements may be used. For example, centering arms may be attached to the levers, such that when the levers are moved to the releasing position, the centering arms position the selectively locking element centrally about the elongate member. A centering frame may extend from the selectively locking element in the second direction over a region of the guidewire in a second direction from the first region and thereby keep the locking element centered with respect to the elongate member. The elongate member may also include an anti-rotation features, which may be used to orient the selectively locking element remotely. These anti-rotation features may include one or more flat regions on the elongate member, or one or more longitudinal grooves or ridges. Radial or longitudinal radiopaque markings may be used. These embodiments, variations thereon, and other embodiments, together with advantages thereof, will be discussed at length below.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]      FIG. 1  is an orthographic view of an embodiment in accordance with the invention;  
         [0005]      FIG. 2  is an orthographic view of the embodiment of  FIG. 1  on an elongate member in accordance with the invention;  
         [0006]      FIG. 3  is an orthographic view of the embodiment of  FIG. 1  on a different portion of the elongate member of  FIG. 2  in accordance with the invention;  
         [0007]      FIG. 4  is an orthographic view of the embodiment of  FIG. 1  on the portion of the elongate member of  FIG. 3  partially disposed in a catheter in accordance with the invention;  
         [0008]      FIG. 5  is an orthographic view of the embodiment of  FIG. 1  attached to a filter in accordance with the invention;  
         [0009]      FIG. 6  is an orthographic view of an embodiment disposed on an elongate member in accordance with the invention;  
         [0010]      FIG. 7  is an orthographic view of an embodiment of the invention disposed on an elongate member in accordance with the invention;  
         [0011]      FIG. 8  is an orthographic view of an embodiment of the invention disposed on an elongate member in accordance with the invention; and  
         [0012]      FIG. 9  is an orthographic view of an embodiment of the invention disposed on an elongate member in accordance with the invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]     The following detailed description should be read with reference to the drawings in which like elements in different drawings are number in like fashion. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. Those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized.  
         [0014]      FIG. 1  is an orthographic view of a locking element  100  attached to a medical device  108  in accordance with the present invention. As will be readily appreciated from further description, medical device  108  may be any suitable medical device such as a filter or therapeutic delivery device. Locking element  100  includes tabs  102 , which move between a locked position and a released position. In this figure, tabs  102  are shown in a locked position and in this embodiment, tabs  102  are biased to be in a locked position. Locking element  100  also includes levers  104 , which move between a locking position and a released position. In this figure, levers  104  are shown in a locking position and in this embodiment, levers  104  are biased to be in a locking position. Tabs  102  and levers  104  are disposed on frame  106 , through which a lumen  110  is disposed. The free ends of tabs  102  are in a first direction from the fixed ends of tabs  102 . Likewise, the fixed ends of tabs  102  are in a second direction from the free ends of tabs  102 . These reference directions will remain constant throughout the several embodiments described. Centering arms  112  may be attached to the second direction ends of levers  104 . While medical device  108  is attached to locking element  100  through struts  114  extending in a second direction from frame  106 , it may be readily appreciated that medical device  108  may be attached through other means such as to levers  104  or centering arms  112 .  
         [0015]     The number and configuration of tabs  102  and levers  104  is, of course, not limited to that depicted in  FIG. 1 . While three tabs  102  and three levers  104  are depicted, embodiments employing as few as one tab  102  or one lever  104  have been contemplated. Likewise, embodiments employing more tabs  102  or levers  104  have been contemplated and the number of tabs or levers used is limited only by the engineering considerations of the particular embodiment. Similarly, although tabs  102  and levers  104  are shown in  FIG. 1  to be in longitudinal alignment, embodiments have been contemplated where tabs  102  and levers  104  are not in alignment. Alignment of tabs  102  and levers  104  is not essential to the invention. As an example, the tabs and levers will, of course, not be in longitudinal alignment when the number of tabs and levers differs. The tabs and levers will be connected to each other such that moving one or more levers from the locking to the releasing position moves one or more tabs from the locked to the released position. In the embodiment shown, tabs  102 , levers  104  and frame  106  form a monolith unit. When levers  104  are moved from the locking position to the releasing position, a force is transmitted through the frame to tabs  102  to move the tabs to the released position. Other means of connecting the levers and the tabs are contemplated, however. One such means is connecting the levers to the rods using gears or hinges. Another means is making a lever and a tab monolithic and pivotably attaching it to the frame using a spring to provide bias towards the locking position.  
         [0016]     Locking element  100  may include elements such as radiopaque bands or longitudinal strips to ease radial and longitudinal position of the device.  
         [0017]     Turning to  FIG. 2 , one can see locking element  100  disposed on elongate member  216 . Elongate member  216  has portion  218  in the first direction and portion  220  in the second direction. The transition between portion  218  and portion  220  is shown as a smooth transition with no sharp edges. The transition need not have this characteristic. Among other examples of suitable transitions, the transition may be a stepwise transition or be a simple frustoconical section, for example. Elongate member  216  is shown as having a circular cross section of uniform shape, but locking element  100  is not limited to being used with elongate members having this characteristic. Elongate member  216  may have any cross sectional shape where a portion of the elongate member in the first direction fits through frame  10 . The cross sectional shape may, for example, be rectangular, triangular, or even irregular. Nor does a cross section at portion  220  need to be smaller than a cross section at portion  210 . Portion  220  may have a longer perimeter or a larger cross sectional area than portion  218 . What is important is that there is a surface region on portion  220  where the distance from the region to the central longitudinal axis of elongate member  216  is less than the distance from a surface region of portion  218  to the longitudinal axis. Thus, for example, an elongate member of generally uniform and circular cross section would suffice if there were a channel in the elongate member in portion  220 . Likewise, an elongate member whose portion  220  was flattened and thereby had a reduced cross sectional thickness but an increased cross sectional width would also suffice. An elongate member of generally constant cross section that has a small region of increased or decreased cross sectional area may work as well.  
         [0018]     Locking element  100  is disposed on portion  218  of elongate member  216 . At this portion, tabs  102  are displaced outward by elongate member  216 , allowing locking element move freely in the first and second directions.  
         [0019]     Turning now to  FIG. 3 , locking element  100  is disposed on portion  220  of elongate member  216 . Tabs  102  are in a locked position, preventing locking element  100  from being moved in the first direction onto portion  218 .  
         [0020]     Turning now to  FIG. 4 , locking element  100  is disposed on portion  220  of elongate member  216 . A catheter  222  is moved on locking element  100  in a second direction. Catheter  222  is sized to move levers  104  from a locking position to a releasing position. When levers  104  are in the releasing position, tabs  102  are moved to the released position and locking element  100  may be moved freely in the first or second direction. Of course, locking element  100  need not be operated using a catheter and other means of moving levers  104  are contemplated. For example, levers  104  could be operated manually or they could be wrapped in a band which shrinks after a period of time or a change of temperature. When levers  104  are in the releasing position, the free ends of centering arms  112  abut against elongate member  216  and generally center locking element  100  with respect to elongate member  216 . This may ease the removal of locking element  100 .  
         [0021]      FIG. 5  is an orthographic view illustrating one use for a locking element  500 , substantially similar to locking element  100 . Locking element  500  is attached with struts  514  to filter  524 , allowing the filter to be selectively locked on a guidewire, for example.  
         [0022]      FIG. 6  is an orthographic view illustrating a locking element  600  according to the invention. Locking element  600  has two limbs  624 , each of which has a tab  602  and a lever  604 . Levers  604  move between a locking and a releasing position and thereby move tabs  602  between a locked position and a released position. Tabs  602  may be biased to the locked position. Limbs  624  are connected to frame  606  from which may extend in a first and a second direction struts  614 . Tubes  608  or medical devices may be attached to the struts. Locking element  600  may be disposed on elongate member  616  which has a portion in the first direction  618  and a portion in the second direction  620 . Portion  620  has a surface region which is closer to the longitudinal axis than a surface region of portion  618 . When locking element  600  is on portion  620  of elongate member  616  and tabs  602  are in the locked position, the locking element will be prevented from moving in the first direction onto portion  618 . The tube  608  in the first direction from locking element  600  may have a centering function. When locking element  600  is on the portion  620  and tabs  602  are in the locked position, the tube may stay on portion  618  and thereby keep the locking element centered with respect to the elongate member.  
         [0023]      FIG. 7  is an orthographic view illustrating a locking element  700  in accordance with the invention. Locking element  700  has a tab  702  attached to a lever  704 . It is of course contemplated that the embodiment of  FIG. 7  may have more than one set of tabs and levers. Lever  704  moves between a locking and a releasing position and thereby moves tab  702  between a locked position and a released position. Lever  704  is attached to frame  706 . Extending in a second direction from frame  706  are struts  714 , which may be connected to a medical device such as a filter or therapeutic deliver system. Locking element  700  is disposed on an elongate member  716 . Elongate member has portion  718  and portion  720 . Portion  720  contains a surface region where the distance from that surface region to a central longitudinal axis is less than the distance from a surface region of portion  718  to the central longitudinal axis. Portion  720  also has ridges  726  disposed on either side of this surface region. Tab  702  is adapted to fit within these ridges when it is in the locked position, thereby preventing rotation of the locking element with respect to the elongate member. This feature may be useful to orient the locking member and attached medical device remotely. Locking element  700  also includes a longitudinal radiopaque stripe  730 . This radiopaque stripe may be used to determine the position of the locking element.  
         [0024]      FIG. 8  is an orthographic view illustrating a locking element  800  disposed on an elongate member  816  in accordance with the invention. Locking element  800  includes tabs  802 , which may move between a locked position and a released position, and levers  804 , which may move between a locking position and a releasing position. Tabs  802  and levers  804  are attached to a frame  806 . Struts may extend in both directions from this frame, attached to medical or other devices. Centering elements  812  may be attached to the levers  804 . When levers  804  are moved to the releasing position, tabs  802  are moved to the released position, thereby allowing locking device  800  to move over portion  818  of elongate member  816 .  
         [0025]      FIG. 9  is an orthographic view illustrating a locking element  900  disposed on an elongate member  916  in accordance with the invention. Locking element  900  has a tab  902  attached to a lever  904 . It is of course contemplated that the embodiment of  FIG. 9  may have more than one set of tabs and levers. Lever  904  moves between a locking and a releasing position and thereby moves tab  902  between a locked position and a released position. Tab  902  and lever  904  are attached to a frame  906 . Struts may extend in a second direction from frame  906 , which may be connected to a medical device such as a filter or therapeutic deliver system. Locking element  900  is disposed on an elongate member  916 . Elongate member has portion  918  and portion  920 . Portion  920  contains a surface region where the distance from that surface region to a central longitudinal axis is less than the distance from a surface region of portion  918  to the central longitudinal axis. Portion  920  also has groove  928  disposed on portion  920 . Tab  902  is adapted to fit in groove  928  when it is in the locked position, thereby preventing rotation of the locking element with respect to the elongate member. This feature may be useful to orient the locking member and attached medical device remotely.  
         [0026]     In use, the locking element may be attached to a filter, therapeutic delivery device, or other medical device. The locking element may be slid in a distal direction over an elongate member. The elongate member will have a second portion in the second direction with a surface region that is closer to the central longitudinal axis of the elongate member than a surface region of a first portion of the elongate member. When the locking element is over the second portion, one or more tabs will move into the locked position, preventing movement in the first direction. To then allow the locking device to move in the first direction, the levers may be moved from the locking position to the releasing position thereby moving the tabs from the locked position to the released position. When the tabs are in the released position, the locking element may then be moved in the first direction.  
         [0027]     As an illustrative example, suppose the selectively locking filter apparatus of  FIG. 5  is put on a guidewire having a stepwise-reduced diameter, where the smaller diameter is distal the larger diameter, inserted percutaneously into a patient. The filter apparatus may be put into a catheter to reduce the diameter of the filter and advanced distally into the patient. When the filter apparatus is on the larger diameter portion of the guidewire, the tabs will be forced to a released position by the guidewire. When the filter apparatus passes the stepwise transition, the tabs will fall into the locked position and the catheter may be withdrawn. A catheter may then be introduced over the filter apparatus again, moving the levers to the releasing position and allowing the filter to be moved proximally off the guidewire.  
         [0028]     The locking element may be made from any number of biocompatible materials. If the locking element is unitary, a combination of flexibility where the material bends at the frame and rigidity in the tabs and levers may be desirable. Merely as examples and not as an exhaustive list, such material may include metals such as stainless steel or Nitinol or may include plastics like nylon or polyvinylchloride. The material may be formed into the locking element or parts of the locking element by laser cutting, molding, welding, brazing or other process well known in the art.  
         [0029]     It will be understood that this disclosure, in many respects, is only illustrative. Changes may be made in details, particularly in matters of shape, size, material, and arrangement of parts without exceeding the scope of the invention. Those skilled in the art will recognize that the present invention may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departures in form and detail may be made without departing from the scope and spirit of the present invention as described in the appended claims.