Patent Document

CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of provisional application No. 61/244,785 (Attorney Docket No. 028414-001000US), filed on Sep. 22, 2009, the full disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0002]    The present invention relates generally to systems and methods for implanting intravascular devices, and more specifically to manual systems and methods for mechanically releasing, detaching or otherwise deploying devices within a body lumen. 
         [0003]    Numerous intravascular implant devices are well known in the field. Many are deployed mechanically, via systems that combine one or more catheters and wires for delivery. Examples of implants that may be delivered mechanically include embolic coils and other elements, stents, grafts, drug delivery implants, and the like. Some obstetric and gastrointestinal implants may also be implanted endolumenally via similar means. Devices that may be released or deployed by mechanical means vary greatly in design, but may employ a similar delivery catheter and wire system. Many such catheter-based delivery systems include a wire for retention of the implant in the catheter until the time for release of the device. These systems are then actuated by retracting or pulling the wire relative to the catheter. Such a wire is referred to herein as a “pull wire”. Examples of implants delivered via catheter and released via a pull wire are described in more detail in U.S. patent application Ser. No. 12/498,752, which is incorporated by reference as if set forth herein in its entirety. 
         [0004]    Precise control of the timing of deployment of the implant is crucial for the successful treatment of vascular and luminal abnormalities. Premature release of an implant can lead to injury and death. The timing of deployment of the implant is under the control of an operator who will retract the pull to release the implant from the distal end of the catheter. The force applied and speed of action will vary among operators, and a single operator may apply force inconsistently. 
         [0005]    Because of the foregoing needs, it is an object of the invention to confer consistent force and speed of release in deployment of a delivery system. It is a further object of the invention to achieve reliable and consistent delivery and deployment of an implant released utilizing a pull wire system. At least some of these objectives will be met by the inventions set forth below. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    An actuation system according to the present invention is intended for use with an implant delivery system that employs a catheter and a pull wire for release of the implant. In a typical procedure utilizing the invention, an implant is loaded into the distal end of a catheter or comparable implant tool. The pull wire is disposed through the length of the catheter with a distal end retaining the implant near the distal end of the catheter and a proximal end remaining in control of the operator. The catheter is then introduced, for example, into the femoral artery and navigated through the vascular system under fluoroscopic visualization. The distal end of the catheter is positioned at the proposed treatment site within the vasculature or other luminal structure of a subject. The treatment site may be, for example, an aneurysm, an arterio-venous malformation, an occlusion, or other defect. Once positioned, the pull wire is retracted relative to the catheter, typically manually, and the implant is released from the catheter distal end and to the particular treatment site. Once released from the catheter, the implant may for example assume a secondary shape selected to optimize treatment, such as filling of an aneurysm cavity, or alternatively, re-establishing patency of a vessel. In some cases, multiple implants may be introduced to a single treatment site, optionally using the same actuation system with multiple delivery catheters. 
         [0007]    In a first aspect of the present invention, a handle for retracting a pull wire disposed in a catheter body comprises a shell having a distal end, a proximal end, and a receptacle at the distal end for receiving a proximal end of the catheter body. A trigger is slidably mounted on an exterior of the shell, and a slider carrying a tripping element is disposed within the shell and coupled to move with the trigger. A shuttle is also slidably disposed within the shell and is coupled to the slider by a first energy storage member, such as an elongate coil spring, where the shuttle carries a wire grabber at its distal end and has a latch member releasably engageable with a stop member fixed to the shell, typically on an inside surface of the shell. Proximal retraction of the trigger by a physician or the user draws the slider proximally within the handle, storing potential energy in the first energy storage member. The stop member immobilizes the shuttle until the tripping element on the slider engages and releases the latch from the stop element, thus allowing the shuttle to be abruptly pulled proximally by release of energy from the first energy storage member, e.g., contraction of the coil springs. In this way, the physician or other user can smoothly pull back the trigger to store sufficient energy to provide the rapid retraction of the pull wire which is desired. 
         [0008]    Usually, the slider will be further adapted to open the wire grabber to release the pull wire when the trigger is fully returned to its initial position. Such decoupling of the pull wire is a safety feature which reduces the risk of inadvertently moving the pull wire to dislodge the implant or otherwise have a deleterious effect. Such automatic release of the wire grabber also resets the handle for use with another catheter and pull wire. 
         [0009]    In a further preferred aspect, initial proximal refraction of the trigger will close the wire grabber to engage the pull wire. Thus, the physician or other user need only insert a proximal end of the catheter into the receptacle at the end of the shell to position the pull wire in the grabber. Engagement of the pull wire then occurs automatically as the trigger is initially retracted. 
         [0010]    The shuttle is initially immobilized relative to the handle by a locking or latching mechanism. The locking mechanism typically comprises a lever pivotally mounted on the shuttle and having a surface which is engaged by a wedge on the slider to open the latch to release the stop when the trigger is fully retracted in the proximal direction. 
         [0011]    The first energy storage member typically comprises an elastic extension member, typically an elongate coil spring, mounted between the slider and the shuttle so that it elongates as the trigger is proximally retracted. The handle assembly will typically include a second energy storage member coupled between the slider and the shell such that proximal refraction of the trigger stores potential energy in the second energy storage member to return the slider to its distal most position when the trigger is released. Usually, the second energy storage member will be a coil compression spring. 
         [0012]    In a second aspect of the present invention, a method for retracting a pull wire in a catheter, typically to release an implant, comprises mating a proximal end of the catheter with a handle. A trigger on the handle is then proximally retracted to proximally translate a slider in the handle to perform the following steps in sequence. First, a grabber disposed on a shuttle is caused to capture a proximal end of the pull wire. Second, potential energy is stored in a first energy storage device coupled between the slider and the shuttle as the slider is proximally retracted. Third, the shuttle is released so that it can be pulled proximally by the energy storage device in order to retract the pull wire relative to the catheter. 
         [0013]    Typically, mating the catheter to the handle comprises aligning a proximal end of the catheter body in a conical receptacle at a distal end of the handle so that the pull wire extends through an opening at the apex of the conical receptacle to pass into the handle. The grabber will typically have a spring-loaded, pivotally mounted lever which closes on the pull wire as a wedge on the slider retracts relative to the shuttle. Thus the pull wire which extends into the handle can be automatically grasped as a trigger is retracted to move a slider relative to the shuttle. 
         [0014]    Usually, the shuttle is initially held in place by a latch on the shuttle which engages a stop on the handle. The shuttle is subsequently released by a trip on the slider which engages and dislodges the latch when the slider is retracted proximally by a pre-selected distance, where the distance is selected to store an appropriate amount of energy in the energy storage device. After release of the pull wire, the trigger may be released so that the slider and shuttle return to their distal-most position and the grabber releases the wire. Typically, the slider and shuttle are caused to return to their distal-most position by the release of energy from a second energy storage device disposed between the slider and the handle, where the second energy storage device had stored potential energy as the trigger was initially retracted. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a perspective view of an embodiment according to the invention. 
           [0016]      FIG. 2A  is a cross-sectional side view of an embodiment according to the invention in a first configuration. 
           [0017]      FIG. 2B  is an area of detail of  FIG. 2A . 
           [0018]      FIG. 3A  is a cross-sectional side view of an embodiment according to the invention in a second configuration. 
           [0019]      FIG. 3B  is an area of detail of  FIG. 3A . 
           [0020]      FIG. 4A  is a cross-sectional side view of an embodiment according to the invention in a third configuration. 
           [0021]      FIG. 4B  is an area of detail of  FIG. 4A . 
           [0022]      FIG. 5A  is a cross-sectional side view of an embodiment according to the invention in a fourth configuration. 
           [0023]      FIG. 5B  is an area of detail of  FIG. 5A . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Referring to  FIG. 1 , general components of a actuation system  10  are illustrated. When in use, actuation system  10  is releasably attached to a proximal end of an endolumenal implant delivery system such as a catheter  19  or a comparable implant delivery tool including a pull wire  16  disposed axially in a catheter body  18 , such as a hypotube. System  10  is held and operated by a practitioner during a procedure to implant one or more devices into the vasculature of a patient. As described in further detail below, system  10  includes a handle  20  which houses mechanisms for grasping a proximal end of the pull wire  16 , and then abruptly retracting the pull wire upon actuation by a user. Operation may be effected by a single pull by the practitioner&#39;s thumb and the implant is thereby deployed in a decisive, consistent, and reliable manner regardless of variations in speed and force applied by the user. 
         [0025]    In order to use system  10 , an implant is loaded into the catheter  19  (for example the coil delivery catheter described in commonly owned, copending application Ser. No. 12/498,752, previously incorporated herein by reference) and carried until the implant and the distal end of catheter  19  are properly positioned in a blood vessel or other body lumen for deployment. The pull wire  16 , extends through catheter body  18 , and the proximal end of the pull wire is loaded into the distal end of handle  20  after positioning a proximal end of the catheter body  18  at the apex of a funnel  12  formed in a distal end of the handle  20 . Although the term “wire” is used herein, it will be understood that any elongated filament of suitable mechanical properties and structure is included in the term. 
         [0026]    While other configurations are within the scope of the invention, handle  20  advantageously includes a finger groove  21  defined by the exterior of handle  20 . Also disposed on the exterior of handle  20  is a thumb grip  34 , which is axially movable along the exterior of handle  20  via a channel or comparable structure  34 ′ ( FIG. 2A ). Thumb grip  34  may be pulled in a proximal direction as indicated by the arrow in  FIG. 1  in order to release or otherwise deploy the implant loaded from the distal end of the catheter  19  (as described in commonly owned, copending application Ser. No. 12/498,752, previously incorporated herein by reference). Thumb grip  34  and handle  20  may be shaped as illustrated in  FIG. 1  or otherwise suitably configured to optimize ergonomic functioning. Similarly, handle  20  may be of any dimensions suitable for optimal handling by a user. 
         [0027]    Handle  20  may be manufactured from a suitable medical grade plastic, such as Santoprene medical grade Thermoplastic Vulcanizate available from ExxonMobil Chemical, or acrylonitrile butadiene styrene (ABS) available from Lustran. Suitable materials include materials that may be sterilized in ethylene oxide or radiation, or in an autoclave. Further, desirable materials include those that are injection moldable and recyclable. The external surfaces of handle  20  are preferably smooth and non-abrasive. The internal components of handle  20  may be manufactured from polycarbonate and silicone available from RTP Co. or similar materials and may additionally include stainless steel, rubber or other suitable materials. Manual actuation system  10  may include additional elements, materials and coatings for securing the components and for smooth inter-operative engagement of the components. 
         [0028]    An overview of the operation of handle  20  is as follows.  FIGS. 2A-5B  illustrate “snapshots” taken throughout the sequence of operational steps of system  10 . They highlight the most significant transition points of the interaction of the components of system  10 , during the retraction of thumb grip  34 . In reality, there are an infinite number of configurations of the working components of handle  20 , but the range of configurations can be divided into separate phases. A first phase can be referred to as a “resting position”, in which thumb grip  34  is not retracted and lies in its distal-most position, as illustrated in  FIG. 2A , and in detail in  FIG. 2B . A “grasping position” in which thumb grip  34  is slightly retracted in the proximal direction (indicated by the arrow) is illustrated in  FIG. 3A , and in detail in  FIG. 3B . After the pull wire  16  is grasped, thumb grip  34  is pulled through a longer “priming phase”, until it reaches a latch release position ( FIGS. 4A-4B ). Following latch release, pull wire  16  is abruptly pulled proximally ( FIGS. 5A-5B ), and the system  10  returns to the initial resting position following release of thumb grip  34 . The pull wire  16  is automatically released from the grabber and the handle is ready for use with another catheter or delivery device. 
         [0029]    A more detailed description of these separate phases of operation of system  10 , with reference again to  FIGS. 2A-5B , includes an overview of the changes in configuration of the mechanisms of system  10  throughout these phases. The principle internal components of handle  20  are grabber  24 , slider  28 , and shuttle  36 . In the “at rest” position, grabber  24  is lifted “open” for receiving pull wire  16  between grabber elements  25  and  27  which are mounted on shuttle  36 . In the “grasping position” grabber elements  25  and  27  are allowed to close on the proximal end of pull wire  16 , thus coupling the pull wire to the shuttle  36 . During the priming phase, thumb grip  34  is proximally retracted to pull slider  28  axially along handle  20 , but shuttle  36  and grabber  24  remain latched to the handle  20  and stationary until slider  28  triggers release of the latch which allows the shuttle to be drawn in a proximal direction by a spring mechanism which, because the shuttle is coupled to grabber  24 , abruptly retracts pull wire  16 . 
         [0030]    The features of the primary mechanisms can be described as follows, though it will be understood that other configurations are possible according to the invention. The “at rest” and “grasping” positions result from interaction between parts of grabber  24  and slider  28 . As shown in  FIG. 2A , grabber  24  includes a rocker arm  22  pivotally connected to shuttle  36  via a pivot point  29 . A spring  23  biases rocker arm  22  to rotate in a clockwise direction to a “closed position”. However, when at rest (prior to initial proximal retraction of the thumb slide  34 ), grabber  24  is held “open” with grabber element  25  lifted away from grabber element  27  by a wedge  26  carried by slider  28 . An upper surface of wedge  26  engages a lower surface of rocker arm  22 , biasing rocker arm  22  upwardly against the force of spring  23 . While the grabber  24  is thus open, the proximal end of pull wire  16  is loaded through a passage  15  at the apex of the funnel  12  into the distal end of handle  20 . The proximal end of catheter  18  is received within funnel  12  but blocked from entry into the handle  20  by channel  15  which is sized to allow the pull wire but not the catheter to pass through. 
         [0031]    An initial, slight retraction of thumb grip  34  (in the direction of the proximal direction indicated by the arrow on  FIG. 3A ) removes the wedge  26  from beneath the rocker arm  22  and allows grabber  24  to grasp the proximal end of wire  16 . Though the change in configuration between “at rest” and “grasping” is quite subtle, the grasping configuration is illustrated in  FIG. 3A  and in detail in  FIG. 3B . Slider  28  is linked to thumb grip  34 . Slider  28  has a wedge  26 . After slight retraction of thumb grip  34 , slider  28  travels axially, and wedge  26  also travels axially, out of nesting engagement with grabber  24 . In turn, retraction of wedge  26  permits spring  23  to bias rocker arm  22  pivotally about pivot point  29 . Grabber element  25  and grabber element  27  can thereby engage or “grasp” wire  16 . Note that while the slider  28 , wedge  26 , and thumb grip  34  are illustrated as a monolithic structure, they could be provided as separate components which are joined or connected by conventional techniques. For the purposes of the present invention, it is important only that they are sufficiently coupled so that they travel in unison as the thumb grip is retracted and later advanced. 
         [0032]    Following grasping of the pull wire, further retraction of thumb grip  34  serves to “prime” system  10  for launch of shuttle  36 . During the “priming” phase, grabber  24  remains stationary, along with pull wire  16  and shuttle  36 . Shuttle  36  (now stationary) is linked to slider  28  (which is being retracted) via extension spring  35 . During refraction of slider  28 , extension spring  35  is progressively stretched, and potential “retraction” energy within extension spring  35  is increasing. Shuttle  36  remains stationary because coupled by a button  52  to a stop  48  formed on or attached to an inner surface of the housing  20 . Priming of the system continues as thumb grip  34  is retracted proximally until a trip  38  on a lower distal portion of slider  28  engages and depresses the button  52  to release the stop  48 , allowing the shuttle  36  to be drawn proximally by spring  35 . (illustrated in  FIGS. 4A-4B ). 
         [0033]    Button  52  extends from latch member  50 , which is cut within a sidewall or otherwise disposed upon shuttle  36 . When system  10  is at rest, and during the priming phase, button  52  rests against stop  48 . With respect to slider  28 , a trip  38  is defined by the proximal end of wedge  26 . Trip  38 , as a matter of course, travels proximally with slider  28  during retraction of slider  28 . When slider  28  is retracted to the point that trip  38  reaches button  52 , trip  38  acts to depress button  52  via latch member  50 , thereby releasing button  52  from its resting position against stop  48 . (See  FIGS. 4A-4B ). The release of button  52  permits the spring action of extension spring  35 , which thereby ‘launches’ shuttle  36  in a proximal direction within handle  20 . (See  FIGS. 5A-5B .) And because pull wire  16  is within the grasp of grabber  24 , this decisive retraction of shuttle  36  also decisively retracts pull wire  16 . And upon the decisive retraction of pull wire  16 , the implant (not pictured) is deployed. 
         [0034]    Referring back to the “priming” phase, during extension of spring  35 , a compression spring  37  is increasingly compressed, and compressive force increases within compression spring  37 . Following the launching phase, the user may then release thumb grip  34 . Upon release of thumb grip  34 , the tension stored in compression spring  37  acts to return slider  28  and shuttle  36  to a neutral position, shown in  FIG. 2A . As full distal travel of the slider  28  causes the wedge  26  to engage and lift the rocker arm  22 . The pull wire  16  is released. This is both a safety feature as detachment of the actuation system  10  from the catheter or other delivery system reduces the risk of inadvertently disturbing the deployed implant as well as a convenience since the handle is then ready to repeat the foregoing process if desired. 
         [0035]    While the invention may be modified and alternative forms may be used, specific embodiments of the invention have been illustrated and described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed. The invention and following claims are intended to cover all modifications and equivalents falling within the spirit and scope of the invention.

Technology Category: 1