Patent Publication Number: US-11382634-B2

Title: Embolic device suited for ease of delivery and placement

Description:
BACKGROUND 
     An aneurysm is a blood bulge formed in a wall of an artery and can develop in any artery, including brain, aorta, legs, and spleen. Various aneurysms are typically formed in a saccular form and if the saccular aneurysm ruptures, a stroke, also known as a subarachnoid hemorrhage, may occur. Open surgery to clip or seal the aneurysm is an option for treating and removing an aneurysm; however, the surgery often carries risks and may be inappropriate or dangerous for larger sizes of aneurysms and/or aneurysms in more sensitive locations. Therefore, treating, reducing, and/or removing aneurysms is important to the long-term health of patients. 
     As an alternative to open surgery, a surgeon may perform a minimally invasive procedure whereby an occlusion embolic device is placed within an artery in an effort to treat the developed aneurysm. In such a procedure, the occlusion embolic device (e.g., a blocking device) is placed into the saccular aneurysm at a position to isolate or block the saccular aneurysm from a blood vessel. The placement of the occlusion embolic device is typically accomplished using a catheter carrying the occlusion embolic device such that the device may be inserted into a blood vessel and steered through the blood vessel to treat the aneurysm. 
     Conventional embolic device deployment systems exhibit difficulties with respect to embolic device placement as maneuvering, placing and releasing the embolic device within an artery inside a patient&#39;s body and are proven to be cumbersome. Further, conventional embolic devices themselves may be difficult to engage, maneuver, and place using such conventional delivery systems. This is especially true for brain aneurysms as the deployment procedure requires accurate placement of the embolic device and any error during the procedure may result in significant damage to the brain. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects and many of the attendant advantages of the claims will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1( a )  is a perspective diagram of a patient with a brain aneurysm; 
         FIG. 1( b )  shows the brain aneurysm of  FIG. 1( a )  in greater detail during treatment; 
         FIGS. 2( a )-( c )  are diagrams of an embolic device delivery system according to an embodiment of the subject matter disclosed herein; 
         FIG. 3  is a diagram of a maneuverable tip of a coupler extending through an upper locking window of an embolic device delivery system shown in  FIGS. 2( a )-( c )  according to an embodiment of the subject matter disclosed herein; 
         FIG. 4  is a diagram of a maneuverable tip of a coupler protruding through a lower locking window of an embolic device delivery system shown in  FIGS. 2( a )-( c )  according to an embodiment of the subject matter disclosed herein; 
         FIG. 5  is a diagram of an actuator handle connected to a proximal end of an embolic device delivery system shown in  FIGS. 2( a )-( c )  according to an embodiment of the subject matter disclosed herein; 
         FIG. 6  is an exploded view of the actuator handle of  FIG. 5  according to an embodiment of the subject matter disclosed herein; 
         FIG. 7  is a flowchart for illustrating a method for delivering an embolic device according to an embodiment of the subject matter disclosed herein; 
         FIGS. 8( a )-( b )  are diagrams of an embolic device delivery system according to a further embodiment of the subject matter disclosed herein; and 
         FIGS. 9( a )-( c )  are diagrams of an embolic device delivery system according to a still further embodiment of the subject matter disclosed herein. 
         FIGS. 10( a )-( c )  are diagrams of an embolic device suited for ease of delivery and placement according to an embodiment of the subject matter disclosed herein. 
         FIG. 11  is a diagram of a monolithic embolic device suited for ease of delivery and placement according to an embodiment of the subject matter disclosed herein. 
         FIGS. 12( a )-( d )  are diagrams of additional embolic devices suited for ease of delivery and placement according to a still further embodiment of the subject matter disclosed herein. 
         FIG. 13  is a diagram of another embodiment of an embolic device suited for ease of delivery and placement according to an embodiment of the subject matter disclosed herein. 
     
    
    
     Note that the same numbers are used throughout the disclosure and figures to reference like components and features. 
     DETAILED DESCRIPTION 
     The subject matter of embodiments disclosed herein is described here with specificity to meet statutory requirements, but this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be interpreted as implying any particular order or arrangement among or between various steps or elements except when the order of individual steps or arrangement of elements is explicitly described. 
     Embodiments will be described more fully hereinafter with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, exemplary embodiments by which the systems and methods described herein may be practiced. The embolic device delivery system may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided such that this disclosure will satisfy the statutory requirements and convey the scope of the subject matter to those skilled in the art. 
     By way of an overview, the subject matter disclosed herein may be directed to an embolic device and a corresponding embolic device delivery system and method. In an embodiment, e.g., an embolic device delivery system comprises a delivery catheter, a coupler disposed inside the delivery catheter, and an embolic device that may be carried and placed by the coupler. In one embodiment, the embolic device includes a primary winding that forms a hollow tube such that a coupler may be threaded therethrough. Further, the embolic device may include a slotted metal tube suited to be affixed to one end of the hollow tube formed by the primary winding. Additionally, the embolic device may include a retaining mechanism that includes one or more protrusions suited to engage with one or more slots of the slotted metal tube. In this manner, the retaining mechanism is affixed to the slotted metal tube and the hollow tube formed by the primary winding in such a way as to allow ease of maneuverability when the retaining mechanism is engaged by a coupler of a delivery catheter that may be part of an embolic procedure system. Additional embodiments may include embolic devices having integral retaining mechanisms as well as retaining mechanisms secured to the primary winding without use of a slotted metal tube. 
     The delivery catheter may be a hollow tube such that the coupler can be slidably disposed inside of the tube with coil engagement mechanism disposed toward the distal end of the tube. In one embodiment, the coupler may be an elongated shape having a loop portion for engaging the coil toward the distal end of the delivery catheter. The loop portion of the coupler may be an elastic material or a shape-memory alloy, such as Nitinol or nickel titanium, such that the loop portion is bendable at various angles. Together, the delivery catheter and coupler may be inserted into an artery and carry an embolic device to an aneurysm for placement near and treatment of the aneurysm. 
     These and other advantages will become more apparent in the detailed descriptions below with respect to  FIGS. 1-12 . 
     Embolic Device Delivery System 
       FIG. 1( a )  is a perspective diagram of a patient  10  with a brain aneurysm  30 . An aneurysm may be formed in any artery of a human body including the heart and the brain. An aneurysm that forms in blood vessels (e.g., arteries)  40  in the brain  20  is called a cerebral aneurysm or brain aneurysm  30 . In this example, the brain aneurysm  30  resembles a balloon. Since the aneurysm  30  is caused due to the weakness of the artery, an aneurysm  30  with or near a thin artery wall  40  may rupture. A ruptured aneurysm (not shown) significantly contributes to the occurrence of a stroke and should be treated prior to rupture.  FIG. 1( b )  shows the brain aneurysm of  FIG. 1( a )  in greater detail and in the midst of a procedure using an embolic delivery device. The embolic device deployment system of  FIG. 1( b )  contains a deployment catheter  50  and, on occasion, a micro catheter  60  inside of the deployment catheter  50 . The conventional embolic deployment system is inserted into the artery  40  and passed through the artery  40  to reach the desired location. At the desired location, the deployment catheter  50  and/or micro catheter  60  releases an embolic device  70  into the inside of the aneurysm  30  or near the aneurysm  30 . 
     Depending on the location or nature of the aneurysm  30 , the embolic device  70  is placed inside of the saccular aneurysm  30  as shown in  FIG. 1( b )  or the neck of the aneurysm to prevent further blood flow going into the aneurysm  30 . The deployment mechanism of the embolic device  70  may include pushing off the embolic device  70  from the deployment catheter  50  as shown in  FIG. 1( b ) ; using a thread or fiber (not shown) for engaging the embolic device  70  and cutting off the thread or fiber when disengaging the embolic device  70 ; using a pressure (not shown), heat (not shown), or electricity (not shown) for releasing the embolic device  70 ; and unlocking an interlocking mechanism to release the embolic device  70  from the deployment catheter  50  (not shown). The interlocking mechanism of the embolic device delivery system typically interlocks an embolic device  70  with a portion of the deployment catheter  50  to carry the embolic device  70  through the inside of the artery  40  such that the deployment catheter  50  maneuvers the artery  40  with the embolic device  70  firmly coupled to the deployment catheter  50 . However, the interlocking mechanisms in the conventional embolic device deployment systems require many components or features to achieve reliability, such as firmly holding the embolic device until the deployment catheter  70  reaches a desired location for effectively releasing the embolic device  70 . Many conventional interlocking mechanisms require an additional locking component to interlock the deployment catheter  50  and embolic device  70  in a fixed manner. Nonetheless, having many components to achieve the reliability and smooth delivery counteract a goal of consistent and reliable delivery due to the highly likelihood of the irregularity or malfunction of the deployment system, which leads to a critical error in the procedure. 
       FIGS. 2( a )-( c )  are diagrams of an embolic device delivery system  100  according to an embodiment of the subject matter disclosed herein.  FIG. 2( a )  shows an embolic device  160  coupled to a delivery catheter  110  in one embodiment. The delivery catheter  110  may include a proximal end  112  and distal end  120  along an axis (not shown) of the delivery catheter  110 . When the distal end  120  of the delivery catheter  110  is inserted into an artery, the distal end  120  may be navigated through an artery to reach a desired location (e.g., a location of the aneurysm). Because the distal end  120  of the delivery catheter  110  is navigated through an artery, the embolic device  160  should be firmly coupled to the distal end  120  of the delivery catheter  110 . The delivery catheter  110  may be designed as an elongated cylinder with a hollow interior tube extending from the proximal end  112  to the distal end  120 . Since the delivery catheter  110  maneuvers through an artery, flexible materials may be used for the delivery catheter  110  as an elongated cylinder. In one embodiment, the flexible materials for the delivery catheter  110  may include a silicone, polyurethane (PU), polyethylene (PE), polyvinylchloride (PVC), polytetrafluoroethylene (PTFE), Polyetheretherketone (PEEK), nylon, as well as metallic catheter components, such as helical hollow stranded tubing, and laser cut flexible tubing. The flexible materials for the delivery catheter  110  may include a helical hollow Strand™ and can be obtained from Fort Wayne Metals, Fort Wayne, Iowa. 
     The elongated cylinder of the delivery catheter  110  further includes a coupler  130  disposed along a central axis of the delivery catheter  110 . The coupler  130  may have a proximal end  132  and distal end  140 . In one embodiment, the proximal end  132  of the coupler  130  may be a linear member that extends through the proximal end  112  of the delivery catheter  110 . The proximal end  132  may further include a mechanism for a surgeon to actuate the coupler  130  by moving the coupler  130  backward inside the delivery catheter  110 , further discussed below in  FIG. 5 . The linear member of the coupler  130  may also form an engagement member toward the distal end  140  of the coupler  130 . In one embodiment, the engagement member  140  may be formed as a small diameter loop made of a shape-memory alloy, such as Nitinol, NiTi, or nickel titanium. The shape-memory alloy possesses super elasticity and unique memory characteristics of the original shape. Thus, the shape-memory alloy may be stretched and maintained in the stretched phase; however, once the alloy is released from the stretch, the alloy will return back to the original shape. The maneuverable engagement member  140  may be further configured to be become more/less rigid and/or more/less flaccid when exposed to heat, electricity, or physical force. As discussed with respect to  FIGS. 2( b ) and 2( c ) , this allows the coupler  130  to engage, maneuver and disengage an embolic device  160  during an embolic device delivery procedure. 
     The embolic device  160  coupled to the delivery catheter  110  may include an embolic device  160  configured to expand once placed at the appropriate location inside the artery or near the aneurysm. In some embodiments, the embolic device  160  may be a platinum coil. The embolic device  160  may also include a proximal end  172  and a distal end  174  and a retaining mechanism  180  may be formed at the proximal end  172  of the embolic device  170  to securely couple with the delivery catheter  110 . In various embodiments, the retaining mechanism  180  may be formed as a closed ring, loop, hoop, or eyelet separately formed from the embolic device  160  and affixed at the proximal end  172  of the embolic device  160 . (See below with respect to  FIG. 10( a )-( c ) ), In a further embodiment, the retaining mechanism  180  may be formed integrally with the embolic device  160 . (See below with respect to  FIG. 11 ). With such a proximal end  172  suited to engage a coupler  130 , the retaining mechanism  180  forms an aperture  190  by which the proximal end  172  of the coupler may engage and penetrate. The retaining mechanism  180  may be made of polypropylene or a platinum filament from the primary wind of the coil. During embolic device placement and delivery, the retaining mechanism  180  (and at times, the entire embolic device  160 ) may be disposed inside the delivery catheter  110  near the distal end  120 . Thus, the diameter of the aperture  190  and the width of the embolic device  160  may be narrower than the inside diameter of the delivery catheter  110  such that the retaining mechanism  180  and embolic device  160  are held inside the distal end  120  of the delivery catheter  110  while being maneuvered through an artery. 
     When the delivery catheter  110  engages with the embolic device  160 , the maneuverable engagement member  140  of the coupler  130  engages with the retaining mechanism  180  at the distal end  120  of the delivery catheter  110  by extending the maneuverable engagement member  140  into the aperture  190  of the retaining mechanism  180 . For this configuration, the inside diameter of the aperture  190  may be slightly wider than the diameter of the maneuverable engagement member  140  such that the retaining mechanism  180  allows a small amount of movement for the maneuverable engagement member  140  to move around the inside of the aperture  190  of the retaining mechanism  180 . In one embodiment, the maneuverable engagement member  140  may be extended upwardly through the aperture  190  by taking an upwardly curved shape. The maneuverable engagement member  140  may be extended downwardly or sideways instead of upwardly in response to rotation of the delivery catheter  110  due to manipulation of the delivery catheter by a surgeon such that a person having an ordinary skill in the art would change the direction of the curves accordingly. In a further embodiment, the maneuverable engagement member  140  maneuver away from the axis of the delivery catheter  110 . Due to the super elasticity and shape memory characteristics of the maneuverable engagement member  140 , the maneuverable engagement member  140  is capable of deforming its shape, such as from a straight configuration to an upwardly curved shape. In a further embodiment, the maneuverable engagement member  140  may be bent vertically at one portion to extend through the aperture  190  of the retaining mechanism  180 . 
     As discussed briefly above, the delivery catheter  110  forms an upper locking window  150  on one side of the interior wall of the hollow tube near the distal end  120  of the delivery catheter  110  and a lower locking window  152  on the other side of the interior wall of the hollow tube near the distal end  120  of the delivery catheter  110 . In one embodiment, the maneuverable engagement member  140  may form a U-shaped curve  154  and the downward curve  154  of the maneuverable engagement member  140  may be maintained with the locking features by the upper locking window  150  and the lower locking window  152 . In this configuration, the bottom of the downward curve  154  of the maneuverable engagement member  140  may be maintained within the lower locking window  152  and the tip  200  of the maneuverable engagement member  140  may be maintained within the upper locking window  150  within the delivery catheter  110  while navigating the delivery catheter  110  into an artery. In another embodiment, the upper locking window  150  is located nearer to the distal end  120  of the delivery catheter  110  than the lower locking window  152  is to the distal end  120  of the delivery catheter  110  such that the maneuverable engagement member  140  is locked with the upper locking window  150  and the lower locking window  152  at the distal end  120  of the delivery catheter  110 .  FIGS. 3 and 4  show cutaway diagrams of the portions of the maneuverable engagement member  140  of the coupler  130  that extends through the upper locking window  150  and the lower locking window  152  of the delivery catheter  110  shown in  FIGS. 2( a )-( c )  according to an embodiment of the subject matter disclosed herein. Specifically,  FIG. 3  describes a left elevational view of an upper locking window  150  of the delivery catheter  110  and  FIG. 4  describes a front elevational view of the lower locking window  152  of the delivery catheter  110 . When the embolic device  160  is in a position coupled to the delivery catheter  110  (see  FIG. 2( a ) ), the maneuverable engagement member  140  engages with the aperture  190  of the retaining mechanism  180  and may be further extended through the upper locking window  150  located above the position of the aperture  190  of the retaining mechanism  180  and the lower locking window  152  to secure the maneuverable engagement member  140  in the position. When the tip  200  of the maneuverable engagement member  140  passes through the lower locking window  152  and reaches the upper locking window  150 , the maneuverable engagement member  140  further curves up such that the tip  200  of the maneuverable engagement member  140  extends through the upper locking window  150 . In a further embodiment, the maneuverable engagement member  140  may bend vertically to extend through the upper locking window  150  as well. Once the maneuverable engagement member  140  is shaped in the upwardly curved position, the maneuverable engagement member  140  maintains its shape until any physical force is applied to the maneuverable engagement member  140 . The upwardly curved shape of the maneuverable engagement member  140  may be formed by physically bending the maneuverable engagement member  140 , such as by hand, or by maneuvering the distal end  120  of the coupler  130  to extend the maneuverable engagement member  140  through the aperture  190  such that the straight original configuration is deformed into the curved shape. In various embodiments, the upper locking window  150  and lower locking window  152  may be formed as a rectangular shape, elliptical shape, oval shape, or round shape. In a still further embodiment, the width of the locking window  150  may be slightly wider than the width of the tip  200  of the maneuverable engagement member  140 . As such, the inside of the locking window  150  allows limited movement of the tip  200  to move around such that the tip  200  is secured in the locking window  150 . 
     In addition to the locking mechanisms by the upper and lower locking windows  150 ,  152 , a cross bar  156  extending perpendicular to the axis of the hollow tube of the delivery catheter  110  may further limit the movements of the coupler  130  both in the distal direction  140  and proximal direction  132 . When the embolic device  160  is in a position coupled to the delivery catheter  110  (see  FIG. 2( a ) ), the coupler  130  may be slid toward the distal direction. However, during the sliding, the curve of the maneuverable engagement member  140  contacts with the cross bar  156  and prevents further movement in the distal direction. Further, when the coupler  130  moves proximally, the retaining mechanism  180  and maneuverable engagement member  140  may make contact with the cross bar  156  such that further movement in the proximal direction  132  may be prevented. 
       FIG. 5  shows an actuation mechanism or handle  300  connected to a proximal end  112  of an embolic device delivery system  100  shown in  FIGS. 2( a )-( c )  according to an embodiment of the subject matter disclosed herein. The actuation handle  300  for maneuvering the coupler  130  of the delivery catheter  110  to release an embolic device  160  from the coupler  130  described in  FIGS. 2( a )-2( c ) . The actuation handle  300  may be any suitable means by which a surgeon may easily maneuver the coupler  130  in the lineal direction within an artery of a patient. In one embodiment, the handle  300  is a simple mechanical handle  250  that can pull the coupler in the distal direction. In  FIG. 5 , the actuator handle  300  is shown including a distal member  310 , proximal member  330 , rotating barrel  320 , outer shaft  350 , and inner shaft  360 . Those components  310 ,  320 ,  330 ,  350 , and  360  are coupled each other. In another embodiment, an adhesive may be placed between outer shaft  350  and proximal member  330  such that the outer shaft  370  is stably fixed to the proximal member  330 . The actuator handle  330  is designed for a surgeon to hold the distal member  310  in his/her hand such that the rotating barrel  320  can be held by a forefinger and thumb of the surgeon to rotate in right or left directions. In one embodiment, rotating the rotating barrel  320  in the left direction may extend the inner shaft  360  to the proximal direction and rotating the rotating barrel  320  in the right direction may shorten the inner shaft  360  in the distal direction. 
       FIG. 6  shows an exploded view of the actuation handle  300  of  FIG. 5 . The distal member  310  is directly coupled to the rotating barrel  320  and may be coupled by way of screw structure formed inside of the retaining barrel  320 . The proximal member  330  has two windows, a view window  334  and shuttle window  332 . A shuttle  340  is placed within the shuttle window  332  and moves from the distal direction to the proximal direction. In one embodiment, the shuttle  340  may move from the distal direction to the proximal direction when the rotating barrel  320  is rotated to the left direction. The shuttle  340  is connected to the inner shaft  360  such that the movement of the rotating barrel  320  to the left direction extends the inner shaft  360  to the proximal direction by way of moving the shuttle  340  into the proximal direction. The view window  334  may use a marker to slide within the view window  334  such that a surgeon can see how much the inner shaft  360  has moved to the proximal direction. On the other hand, the outer shaft is coupled to the proximal member  330  and allows the inner shaft  360  to move through within the inner of the outer shaft  350 . 
     Referring back to  FIG. 2( a )-( c ) ,  FIG. 2( b )  shows the embolic device  160  in a position to be released from the delivery catheter  110  according to an embodiment of the subject matter disclosed herein. When the delivery catheter  110  reaches the desired location (e.g. an aneurysm), the release of the maneuverable engagement member  140  may be actuated by a surgeon by pulling the linear member of the coupler. In this embodiment, the release of the maneuverable engagement member  140  occurs when the proximal end  132  of the coupler  130  is pulled toward the proximal end  112  of the delivery catheter  110 . Then, the downward curve  154  of the maneuverable engagement member  140  may be pulled up from the lower locking window  152  and the tip  200  of the maneuverable engagement member  140  may be simultaneously pulled down from the locking window  150 . The tip  200  of the maneuverable engagement member  140  may be further pulled down through the aperture  190  of the retaining mechanism  180  of the embolic device  160  and the downward curve  154  of the maneuverable engagement member  140  is completely taken out from the lower locking window  152 . While the maneuverable engagement member  140  passes through the aperture  190 , an edge  210  of the retaining mechanism  180  presses the upwardly curved or bent portion of the maneuverable engagement member  140  and a lower side of the cross bar  156  to make the curved or bent portion slightly straight such that the maneuverable engagement member  140  may be easily pulled out from the aperture  190 . When the tip  200  of the maneuverable engagement member  140  passes through the lower of the cross bar  156 , the cross bar  156  further pushes the upwardly curved or bent portion down, such that the tip  200  becomes straighter. This will help the maneuverable engagement member  140  to be pulled clearly inside of the delivery catheter  110  without dragging or scratching the inside wall of the catheter  110 . 
       FIG. 2( c )  shows the embolic device  160  being completely disengaged from the delivery catheter  110  in one embodiment. When the coupler  130  is pulled proximally and once the tip  200  of the maneuverable engagement member  140  is pulled out from the aperture  190  of the retaining mechanism  180 , the embolic device  160  is disengaged from the distal end  120  of the delivery catheter  110 . Then, the surgeon may carefully remove the entire delivery catheter  110  by pulling the delivery catheter  110  out from the artery to complete the procedure. 
       FIG. 7  is a flowchart for illustrating a method  400  for delivering an embolic device  160  according to an embodiment of the subject matter disclosed herein. Prior to insertion into any artery, the embolic device  160  may be engaged with the delivery catheter  110  by engaging the maneuverable engagement member  140  of the coupler  130  with the aperture  190  of the retaining mechanism  180  (step  410 ). The maneuverable engagement member  140  of the coupler  130  forms a curved shape and further extends into the upper locking window  150  and lower locking window  152  of the delivery catheter  110 , such that the coupler  130  secures the embolic device  160  with the delivery catheter  110  (step  420 ). The delivery catheter  110  is inserted into an artery and navigated to the desired location of the artery with the embolic device  160  retained by the delivery catheter  110  (step  430 ). When the delivery catheter  110  reaches the desired location, the proximal end of the coupler  130  is pulled proximally (step  440 ). By pulling, the maneuverable engagement member  140  of the coupler  130  is withdrawn from the upper locking window  150  and lower locking window  152  (step  450 ). By further proximally pulling, the maneuverable engagement member  140  is further withdrawn from the aperture  190  of the retaining mechanism  180  (step  460 ). When the tip  200  of the maneuverable engagement member  140 , especially the curved shape of the maneuverable engagement member  140  contacts a cross bar  156 , the cross bar  156  pushes the maneuverable engagement member  140  down, such that the tip  200  is not dragged or scratched within the delivery catheter  110  (step  470 ). Once the tip  200  of the maneuverable engagement member  140  is completely withdrawn from the aperture  190 , the embolic device  160  is released from the delivery catheter  110  and the delivery catheter is withdrawn from the artery (step  480 ). 
       FIGS. 8( a )-( b )  are diagrams of an embolic device delivery system  500  according to a further embodiment of the subject matter disclosed herein. An embolic device delivery system  500  may similarly include a delivery catheter  510 , maneuverable coupler  530 , and embolic device  560  with a retaining mechanism  580  formed integrally with the embolic device  560 . The delivery catheter  510  may be a hollow tube to receive the maneuverable coupler  530  and the retaining ring  580  of the embolic device  560  within. Toward the distal end  520  of the delivery catheter  510 , the maneuverable coupler  530  forms a U-shaped curve engagement member  540  to engage with the retaining mechanism  580 . The engagement member  540  may be formed as a small diameter loop made of a shape-memory alloy, such as Nitinol, NiTi, or nickel titanium. The shape-memory alloy possesses super elasticity and unique memory characteristics of the original shape. Thus, the shape-memory alloy may be stretched and maintained in the stretched phase; however, once the alloy is released from the stretch, the alloy will return back to the original shape. The maneuverable engagement member  540  may be further configured to be become more/less rigid and/or more/less flaccid when exposed to heat, electricity, or physical force. As discussed with respect to  FIG. 8( b ) , this allows the maneuverable coupler  530  to engage, maneuver and disengage an embolic device  560  during an embolic device delivery procedure. 
     The delivery catheter  510  forms an upper locking window  550  on one side of the interior wall of the hollow tube near the distal end  520  of the delivery catheter  510  and a lower locking window  552  on the other side of the interior wall of the hollow tube near the distal end  520  of the delivery catheter  510 . In this embodiment, the upper locking window  552  is located relatively closer to the distal end  520  of the delivery catheter  510  compared to the upper locking window  150  of the embolic device delivery system  100  described in  FIGS. 2( a )-( c ) . In one embodiment, the maneuverable engagement member  540  may form a U-shaped curve  554  and the downward curve  554  of the maneuverable engagement member  540  may be maintained with the locking features by the upper locking window  550  and the lower locking window  552 . In this configuration, the bottom of the downward curve  554  of the maneuverable engagement member  540  may be maintained within the lower locking window  552  and a tip  600  of the maneuverable engagement member  540  may be maintained within the upper locking window  550  while navigating the delivery catheter  510  into an artery. In this locking position, an elongated portion  556  of the maneuverable engagement member  540  between the U-shaped curve  554  and the tip  600  forms almost a straight line and the tip  600  may stably extend into the upper locking window  550  in a vertical position. In another embodiment, the upper locking window  550  is located nearer to the distal end  520  of the delivery catheter  510  than the lower locking window  552  is to the distal end  520  of the delivery catheter  510  such that the maneuverable engagement member  540  is locked with the upper locking window  150  and the lower locking window  552  at the distal end  520  of the delivery catheter  510 . The maneuverable engagement member  540  extends through the upper locking window  550  and the lower locking window  552  of the delivery catheter  510  similar to the upper locking window  150  in the left elevational view described in  FIG. 3  and the lower locking window  152  in the front elevational view described in  FIG. 4 . 
     When the embolic device  560  is in a position coupled to the delivery catheter  510  (see  FIG. 8( a ) ), the maneuverable engagement member  540  engages with the aperture  590  of the retaining mechanism  580  and may be further extended through the upper locking window  550  located above the position of the aperture  590  of the retaining mechanism  580  and the lower locking window  552  to secure the maneuverable engagement member  540  in the position. Once the maneuverable engagement member  540  is shaped in the upwardly curved position, the maneuverable engagement member  540  maintains its shape until any physical force is applied to the maneuverable engagement member  540 . The upwardly curved shape of the maneuverable engagement member  540  may be formed by physically bending the maneuverable engagement member  540 , such as by hand, or by maneuvering the distal end  520  of the maneuverable engagement member  540  to extend the maneuverable engagement member  540  through the aperture  590  such that the straight original configuration is deformed into the curved shape. In various embodiments, the upper locking window  550  and lower locking window  552  may be formed as a rectangular shape, elliptical shape, oval shape, or round shape. In a still further embodiment, the width of the locking window  550  may be slightly wider than the width of the tip  600  of the maneuverable engagement member  540 . As such, the inside of the locking window  550  allows limited movement of the tip  600  to move around such that the tip  600  is secured in the locking window  550 . 
       FIG. 8( b )  shows the embolic device  560  in a position to be released from the delivery catheter  510  according to an embodiment of the subject matter disclosed herein. When the delivery catheter  510  reaches the desired location (e.g. an aneurysm), the release of the maneuverable engagement member  540  from the retaining mechanism  580  may be actuated by a surgeon by pulling the linear member of the maneuverable engagement member  540 . In this embodiment, the release of the maneuverable engagement member  540  occurs when the proximal end (not shown) of the maneuverable engagement member  540  is pulled toward the proximal end of the delivery catheter  510 . Then, the downward curve  554  of the maneuverable engagement member  540  may be pulled up from the lower locking window  552  and the tip  600  of the maneuverable engagement member  540  may be simultaneously pulled down from the locking window  550 . The tip  600  of the maneuverable engagement member  540  may be further pulled down through the aperture  590  of the retaining mechanism  580  of the embolic device  560  and the downward curve  554  of the maneuverable engagement member  540  is completely taken out from the lower locking window  552 . While the maneuverable engagement member  540  passes through the aperture  590 , an edge  610  of the retaining mechanism  580  presses the upwardly curved or bent portion of the maneuverable engagement member  540  to make the curved or bent portion slightly straight such that the maneuverable engagement member  540  may be easily pulled out from the aperture  590 . When the maneuverable engagement member  540  is pulled proximally and once the tip  600  of the maneuverable engagement member  540  is pulled out from the aperture  590  of the retaining mechanism  580 , the embolic device  560  is disengaged from the delivery catheter  510 . Then, the surgeon may carefully remove the entire delivery catheter  510  by pulling the delivery catheter  510  out from the artery to complete the procedure. 
       FIGS. 9( a )-( c )  are diagrams of an embolic device delivery system  700  according to a still further embodiment of the subject matter disclosed herein. An embolic device delivery system  700  may similarly include a delivery catheter  710 , maneuverable coupler  730 , and embolic device  760  with a retaining mechanism  780  formed integrally with the embolic device  760 . The delivery catheter  710  may be a hollow tube to receive the maneuverable coupler  730  and the retaining ring  780  of the embolic device  760  within. Toward the distal end  720  of the delivery catheter  710 , the maneuverable coupler  730  forms a U-shaped curve open loop engagement member  740  to engage with the retaining mechanism  780 . In one embodiment, the maneuverable engagement loop  740  may form an upward U-shaped curve and the retaining mechanism  780  may form a downward curve such that the maneuverable engagement loop  740  can engage with the retaining  780  mechanism in an interlocking position. The engagement loop  740  may be formed as a small diameter loop made of a shape-memory alloy, such as Nitinol, NiTi, or nickel titanium. The shape-memory alloy possesses super elasticity and unique memory characteristics of the original shape. Thus, the shape-memory alloy may be stretched and maintained in the stretched phase; however, once the alloy is released from the stretch, the alloy will return back to the original shape. The maneuverable engagement loop  740  may be further configured to become more/less rigid and/or more/less flaccid when exposed to heat, electricity, or physical force. As discussed with respect to  FIGS. 9( b ) and 9( c ) , this allows the maneuverable coupler  730  to engage, maneuver and disengage an embolic device  760  during an embolic device delivery procedure. Within the hollow tube of the delivery catheter  710 , a loop reducer  820  may be placed for the maneuverable engagement loop  740  to maintain the location inside of the delivery catheter  710 . The loop reducer  820  has an opening (not shown) to receive the linear member of the maneuverable coupler  730  extending from the proximal end (not shown) to the distal end  720  of the delivery catheter  710 . In a further embodiment, the distal end  720  of the delivery catheter may have a cutout  830  for the retaining mechanism  580  of the embolic device can be maintained without any difficulties. 
     When the embolic device  760  is in a position coupled to the delivery catheter  710  (see  FIG. 9( a ) ), the maneuverable engagement loop  740  may be simply extended through the aperture  790  of the retaining mechanism  780 . Once the maneuverable engagement loop  740  is shaped in the upwardly curved position, the maneuverable engagement loop  740  maintains its shape until any physical force is applied to the maneuverable engagement loop  740 . In one embodiment, the upwardly curved shape of the maneuverable engagement loop  740  may be formed by physically bending the maneuverable engagement loop  740 , such as by hand, or by maneuvering the distal end  720  of the maneuverable engagement loop  740  to extend the maneuverable engagement loop  740  through the aperture  790  such that the straight original configuration is deformed into the curved shape. In a further embodiment, the width of the maneuverable engagement loop  740  may be slightly narrower than the width of the aperture  790  of the retaining mechanism  780 . As such, the inside of the aperture  790  of the retaining mechanism  780  allows limited movement of the maneuverable engagement loop  740  to move around such that the maneuverable engagement loop  740  is secured in the retaining mechanism  780 . 
       FIG. 9( b )  shows the embolic device  760  in a position to be released from the delivery catheter  710  according to a still further embodiment of the subject matter disclosed herein. When the delivery catheter  710  reaches the desired location (e.g. an aneurysm), the release of the maneuverable engagement loop  740  from the retaining mechanism  780  may be actuated by a surgeon by pulling the linear member of the maneuverable coupler  730 . In this embodiment, the release of the maneuverable engagement loop  740  occurs when the linear member of the maneuverable coupler  730  is pulled toward the proximal end (not shown) of the delivery catheter  710 . Then, the maneuverable engagement loop  740  may be pulled from the aperture  790  of the retaining mechanism  780  of the embolic device  760  and go through the opening of the loop reducer  820 . While the maneuverable engagement loop  740  passes through the opening of the loop reducer  820 , an edge  800  of the maneuverable engagement loop  740  presses the open loop of the maneuverable engagement loop  740  to make the loop portion closed such that the maneuverable engagement loop  740  may be easily pulled out from the opening of the loop reducer  820 . 
       FIG. 9( c )  shows the embolic device  760  being completely disengaged from the delivery catheter  710  in one embodiment. When the maneuverable engagement loop  740  is pulled proximally and once the tip  800  of the maneuverable engagement loop  740  is pulled out from the aperture  790  of the retaining mechanism  780 , the embolic device  760  is disengaged from the delivery catheter  710 . Then, the surgeon may carefully remove the entire delivery catheter  710  by pulling the delivery catheter  710  out from the artery to complete the procedure. 
     Embolic Device Suited for Ease of Use in Delivery System 
       FIGS. 10( a )-( c )  are diagrams of an embolic device suited for ease of delivery and placement according to an embodiment of the subject matter disclosed herein. The various embodiments described with respect to  FIGS. 10( a )-( c )  are each examples of embolic devices that are suited to be used with the embolic device delivery system  100  as described above with respect to  FIGS. 1-9 . Some of these embodiments may be better suited for different operations and different performance characteristics. The various embodiments are detailed below in relation to each of  FIGS. 10( a )-( c ) . As such, each embolic device described herein includes a retaining mechanism  180  having an aperture  190  (as enumerated in  FIGS. 2   a/b ). 
       FIG. 10( a )  shows a diagram of a retaining mechanism  1000  (e.g., a wire form) suited to be used as a portion of an embolic device and coupled to a proximal end of an embolic device. The retaining mechanism  1000  takes the shape of a closed metal loop that may be inserted and secured in one or more ways to a proximal end of an embolic device. Further, the retaining mechanism  1000  serves the purpose in the overall embolic device as is described above with respect to the retaining mechanism  180  as discussed above with respect to  FIGS. 1-9 . In the retaining mechanism  1000  of  FIG. 10( a ) , the aperture  190  is formed at a major end  1001  of the retaining mechanism  1000 . The retaining mechanism  1000  in  FIG. 10( a )  includes two ends including the aforementioned major end  1001  and a minor end  1003 . The major/minor end distinction only applies to relative size of each end as one can see a difference in relative diameter between the major end  1001  and the minor end  1003 . The major end  1001  and minor end  1003  are coupled together via an elongated middle section  1002  that is relatively linear in coupling the semicircular shapes of the major end  1001  and the minor end  1003 . 
     The retaining mechanism  1001  as shown in  FIG. 10( a )  is suited to be securely affixed to a proximal end of an embolic device (not shown in  FIG. 10( a ) ) such that the aperture  190  formed at the major end  1001  of the retaining mechanism  1000  is suited to be engaged by a coupler (e.g., coupler  130  as shown in  FIG. 2( a ) ) as described above. Thus, the coupler (not shown in  FIG. 10( a ) ) may engage the retaining mechanism  1000  and push/pull (or otherwise maneuver) the attached embolic device using the maneuverability aspects of the embolic device delivery system as discussed previously. The manner in which the retaining mechanism  1000  is coupled to the embolic device varies as is discussed in the various embodiments described next with respect to  FIGS. 10( b )-( c ) . 
       FIG. 10( b )  shows a diagram of a first manner of coupling the retaining mechanism  1000  as shown in  FIG. 10( a )  to an embolic device  160  according to one embodiment of the subject matter discussed herein. In this embodiment, the retaining mechanism  1000  may have its minor end  1003  inserted into the end of a primary wind of an embolic device  160 . The primary wind of the embolic device  160  has a pitch such that the turns/pitches most proximal to the end that engages the wire form  1000  are slightly opened (as one can see as the retaining mechanism  1000  positioned through the last 3-5 pitch turns becomes slightly larger in diameter). Once positioned, a laser (not shown) may be fired directly between the slightly opened pitch, which causes the retaining mechanism  1000  and interior of the primary winding of the most proximal end of the embolic device to fuse together. The fusing is indicated by the stars  1010   a  and  1010   b . In some embodiments, the retaining mechanism  1000  may also be fused slightly away from the central axis of the primary winding of the embolic device so there is enough of a line of site through the primary winding for also realizing one or more fuse points in the interior of the embolic device. This interior fuse point is indicated by the two fuse points  1010   c.    
       FIG. 10( c )  shows a diagram of a second manner of coupling the retaining mechanism  1000  as shown in  FIG. 10( a )  to an embolic device  160  according to one embodiment of the subject matter discussed herein. In this embodiment, the retaining mechanism  1000  is affixed to the primary winding of the embolic device using adhesive  1015 . In this manner, an adhesive may be placed inside the primary winding at the proximal end of the embolic device  160  such that the minor end  1003  of the retaining mechanism  1000  may be inserted into the primary winding where the adhesive is placed. Then, the adhesive  1015  may cure (e.g., dry, or otherwise harden, for example, through application of ultra-violet (UV) light) and subsequently secure the retaining mechanism  1000  to the primary winding of the embolic device  160 . 
       FIG. 11  shows a diagram of a monolithic solution wherein a major end  1001  of the retaining mechanism  1000  is part and parcel (e.g., integral) with the primary winding of the embolic device  160 . As shown, the primary winding may include an end (e.g., the proximal end) that includes a bent-out portion  1020  that forms the major end  1001  of a retaining mechanism in forming an aperture  190  that may engage a coupler of an embolic device delivery system as discussed above. This solution provides a monolithic solution (e.g., the primary winding also includes the bent-out portion  1020  that forms a major end  1001  of a retaining mechanism  1000 ) and therefore, fusing, welds, and/or adhesives are not needed. 
       FIGS. 12( a )-( d )  are diagrams of additional embolic devices suited for ease of delivery and placement according to still further embodiments of the subject matter disclosed herein. In these embodiments, a retaining mechanism may be used in conjunction with a slotted metal tube for assisting in holding the retaining mechanism in place. In this manner, the slotted metal tube provides a more robust portion of the overall embolic device so that the retaining mechanism may be flash welded (e.g., fused) to a portion of the embolic device that will not be compromised by the heat generated during the fusing procedure. These and other aspects are discussed below with respect to  FIGS. 12( a )-( d ) . 
       FIG. 12( a )  shows a diagram of a first embodiment of a retaining mechanism  1200  suited for use with a slotted metal tube portion of an embolic device (not shown in  FIG. 12( a ) ). The retaining mechanism  1200  includes a major end  1204  that feature an aperture  190  form by a closed end loop structure. However, different form the retaining mechanism  1000  as shown in  FIG. 10( a ) , there is no minor end. Instead, the retaining mechanism  1200  includes a base portion  1212  that includes a number of features for assisting is securing the retaining mechanism to the slotted metal tube as well as to a coupler wire and/or the primary winding. 
     A first feature of the base portion  1212  of the retaining mechanism  1200  includes first and second protrusions  1205   a/b  that are positioned adjacent to the major end  1204  and offset enough to protrude through slots of a metal slotted tube. In this manner, the protrusions  1205   a/b  provide purchase to the slotted metal tube in assisting with securing the retaining mechanism into place. Further, a second feature includes a coupler orifice  1210  suited for receiving a proximal end of a coupler wire  1214  through the coupler orifice  1210 . In this manner, the coupler wire  1214  may be threaded through the coupler orifice  1210  toward the aperture  190 . Then, the coupler wire  1214  may be formed into a suture  1215  to prevent the coupler wire  1214  from being maneuvered back out of the coupler orifice  1210  of the base portion  1212 . This suture  1215  then secures the coupler wire  1214  to the overall retaining mechanism  1200 . Likewise, if the retaining mechanism  1200  is then secured to a slotted metal tube (e.g., because the protrusions  1205   a/b  are positioned in slots of a slotted metal tube), the overall embolic device may be maneuvered using an embolic device delivery system having a capability of manipulating the coupler wire  1214 . 
       FIG. 12( b )  shows a diagram of a second embodiment of a retaining mechanism  1250  suited for use with a slotted metal tube portion of an embolic device (not shown in  FIG. 12( b ) ). The retaining mechanism  1250  includes a major end  1204  that feature an aperture  190  form by a closed end loop structure. Similar to that which was discussed above, this retaining mechanism  1250  is different form the retaining mechanism  1000  as shown in  FIG. 10( a ) , as there is no minor end. Instead, the retaining mechanism  1250  includes a base portion  1212  that includes a number of features for assisting is securing the retaining mechanism to the slotted metal tube as well as to a coupler wire and/or the primary winding. 
     A first feature of the base portion  1212  of the retaining mechanism  1250  again includes first and second protrusions  1205   a/b  that are positioned adjacent to the major end  1204  and offset enough to protrude through slots of a metal slotted tube. In this manner, the protrusions  1205   a/b  provide purchase to the slotted metal tube in assisting with securing the retaining mechanism into place. Further, a second feature includes a slotted coupler orifice  1255  having first and second internal protrusions  1253   a/b  suited for receiving a proximal end of a coupler wire  1214  through the slotted coupler orifice  1255 . In this manner, the coupler wire  1214  may be threaded through the slotted coupler orifice  1255  toward the aperture  190 . Then, the coupler wire  1214  may be formed into a suture  1215  to prevent the coupler wire  1214  from being maneuvered back out of the slotted coupler orifice  1255  of the base portion  1212 . This suture  1215  then secures the coupler wire  1214  to the overall retaining mechanism  1250 . Likewise, if the retaining mechanism  1250  is then secured to a slotted metal tube (e.g., because the protrusions  1205   a/b  are positioned in slots of a slotted metal tube), the overall embolic device may be maneuvered using an embolic device delivery system having a capability of manipulating the coupler wire  1214 . The retaining mechanisms  1200  and  1250  of  FIGS. 12( a ) and 12( b )  may be utilized with an embolic device  160  having a slotted metal tube as discussed next with respect to  FIGS. 12( c ) and 12( d ) . 
       FIG. 12( c )  shows a diagram of the retaining mechanism  1200  of  FIG. 12( a )  coupled with a slotted metal tube as discussed above according to an embodiment of the subject matter disclosed herein. As skilled artisan understands that the retaining mechanism  1250  of  FIG. 12( b )  as described above may be also be interchangeably with the retaining mechanism  1200  as shown in  FIGS. 12( c ) and 12( d ) . However, the retaining mechanism  1200  will only be referenced strictly for ease of illustration in in  FIGS. 12( c ) and 12( d ) . Thus, one can see that the slotted metal tube  1270  includes a first visible slot  1271  having one protrusion  1205   a  of the retaining mechanism  1200  inserted therein. Though it cannot be seen in this view, it is understood that the second protrusion  1205   b  protrudes though a second slot on the opposite side of the slotted metal tube  1270  in a similar manner. As the slotted metal tube  1271  is more robust than the primary winding of any attached embolic device, a fusing laser may be aimed at the protrusion  1205   a  protruding through the first slot  1271  such that the protrusion  1205   a  and the slot  1271  are fused together. A similar fusing may occur with respect to the unseen slot and protrusion  1205   b . Therefore, the retaining mechanism  1200  and the slotted metal tube  1270  may be maneuvered as one cohesive unit. As discussed next, if the slotted metal tube  1270  is coupled to an embolic device (not shown in  FIG. 12( c ) ), the entire assembly may be maneuvered by engaging the retaining mechanism  1200 . 
       FIG. 12( d )  shows a diagram of the slotted metal tube  1270  of  FIG. 12( c )  attached to an embolic device  160  according to an embodiment of the subject matter disclosed herein. As alluded to previously, the combination of the slotted metal tube  1270  and the retaining mechanism  1200  may be affixed to a proximal end of an embolic device. In one embodiment, this may be accomplished using a laser to create a flash weld  1290  between one end of the slotted metal tube  1270  and an end of the primary winding of the embolic device  160 . In this manner, the assembly may be maneuvered as discussed in several embodiment above. 
       FIG. 13  is a diagram of another embodiment of a retaining mechanism  1300  an embolic device suited for ease of delivery and placement according to an embodiment of the subject matter disclosed herein. This embodiment as described with respect to  FIG. 13  is another example of a retaining mechanism  1300  that is suited to be used with the embolic device delivery system  100  as described above with respect to  FIGS. 1-9 . As before, this embolic device (not shown) described here includes a retaining mechanism  1300  having an aperture  190  (as enumerated in  FIGS. 2   a/b ). 
       FIG. 13  shows a diagram of a retaining mechanism  1300  (e.g., a wire form) suited to be used as a portion of an embolic device (not shown) whereby this retaining mechanism is coupled to a proximal end of an embolic device (as shown with respect to the embodiment of  FIGS. 10( a )-( c ) . The retaining mechanism  1300  takes the shape of a closed metal loop that may be inserted and secured in one or more ways to a proximal end of an embolic device. Further, the retaining mechanism  1300  serves the purpose in the overall embolic device as is described above with respect to the retaining mechanism  180  as discussed above with respect to  FIGS. 1-9 . In the retaining mechanism  1300  of  FIG. 13 , the aperture  190  is formed at a major end  1301  of the retaining mechanism  1300 . The retaining mechanism  1300  in  FIG. 13  includes two ends including the aforementioned major end  1301  and a minor end  1303 . The major/minor end distinction only applies to relative size of each end as one can see a difference in relative diameter between the major end  1301  and the minor end  1303 . The major end  1301  and minor end  1303  are coupled together via an elongated middle section  1302  that is relatively linear in coupling the semicircular shapes of the major end  1301  and the minor end  1303 . Further, in this embodiment, the minor end  1303  may include a tapering or narrowing shape culminating in the minor end  1303 . 
     The retaining mechanism  1301  as shown in  FIG. 13  further comprises a central support structure  1310  designed to provide additional physical support for the overall loop structure of the retaining mechanism  1300 . The support structure resembles an elongated tube having a first curved pocket  1311   a  suited to secure a first side of the elongated middle section  1302  and a second curved pocket  1311   b  suited to secure a second side of the elongated middle section  1302 . The central support structure  1310  provides additional support for the overall retaining mechanism  1300  to be securely affixed to a proximal end of an embolic device (not shown in  FIG. 13 ) such that the aperture  190  formed at the major end  1301  of the retaining mechanism  1300  is suited to be engaged by a coupler (e.g., coupler  130  as shown in  FIG. 2( a ) ) as described above. Thus, the coupler (not shown in  FIG. 13 ) may engage the retaining mechanism  1300  and push/pull (or otherwise maneuver) the attached embolic device using the maneuverability aspects of the embolic device delivery system as discussed previously. The manner in which the retaining mechanism  1300  is coupled to the embolic device varies as is discussed above in the various embodiments described with respect to  FIGS. 10( b )-( c ) . 
     All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and/or were set forth in its entirety herein. 
     The use of the terms “a” and “an” and “the” and similar referents in the specification and in the following claims are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “having,” “including,” “containing” and similar referents in the specification and in the following claims are to be construed as open-ended terms (e.g., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value inclusively falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments and does not pose a limitation to the scope of the disclosure unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to each embodiment of the present disclosure. 
     Different arrangements of the components depicted in the drawings or described above, as well as components and steps not shown or described are possible. Similarly, some features and sub-combinations are useful and may be employed without reference to other features and sub-combinations. Embodiments have been described for illustrative and not restrictive purposes, and alternative embodiments will become apparent to readers of this patent. Accordingly, the present subject matter is not limited to the embodiments described above or depicted in the drawings, and various embodiments and modifications can be made without departing from the scope of the claims below.