Abstract:
A delivery catheter with a plug ejection mechanism with a fluid filled actuator incorporated in the catheter handle is disclosed. After delivery of RF energy, the plug is deployed within the region of the lesion by activating the plug ejection mechanism. A delivery catheter used for female sterilization with an atraumatic ball tip and an opening in the side wall of the catheter body is disclosed. The delivery catheter includes a hinge that will yield or bend under a certain load to prevent injury to the uterine wall or fallopian tube. The side wall opening is angled to allow proper placement of a plug into the fallopian tube for occlusion of the fallopian tube.

Description:
CROSS-REFERENCES 
       [0001]    The present application is a continuation-in-part of U.S. patent application Ser. No. 11/562,882 filed Nov. 22, 2006 entitled “Delivery Catheter with Implant Ejection Mechanism” currently pending. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The inventions described below relates to a system and method for implanting devices in the fallopian tubes or other vessels of the body. 
       BACKGROUND OF THE INVENTION 
       [0003]    In our prior U.S. patent, Harrington, et al., Flexible Method and Apparatus for Tubal Occlusion, U.S. Pat. No. 6,309,384 (Oct. 30, 2001), we described devices and methods for sterilization of female patients. Our sterilization method involves thermally wounding a small area of the patient&#39;s utero-tubal junction with relatively low power, and placing a foam plug within the wounded area. The method is facilitated by our catheter system, which comprises a catheter with a wounding segment which fits into the utero-tubal junction and carries the plug. The wounding segment comprises a short tubular extension slidably mounted within the distal tip of the catheter. The foam plug is stored within the wounding segment. The plug is deposited in the ovarian pathway when the wounding segment is retracted over the plug (a stationary holding rod within the catheter holds the plug in place relative to the catheter, so that retraction of the wounding segment exposes the plug). 
       SUMMARY 
       [0004]    In one aspect of the present invention, the systems and methods described below provide for smooth ejection or release of a contraceptive plug or other implant in a system requiring retraction of a sheath to eject or release the implant. In one embodiment, a plug ejection mechanism is incorporated into the catheter system to retract the sheath within a catheter body while holding the plug in place, thereby exposing the plug. The plug ejection mechanism comprises the sheath, a push rod inside the sheath, and a sheath retraction mechanism which includes a dashpot with a fluid filled chamber and a piston, a pre-loaded spring operably fixed to the sheath, and a latch that prevents any motion of the components until the mechanism is unlatched by the user. A push-button or solenoid-operated unlatching mechanism is provided to release the latch, thereby releasing the spring in the dashpot, thereby drawing the catheter sheath proximally. The fluid-filled chamber of the dashpot dampens the spring action to provide smooth and whip-less ejection of the plug from the sheath. 
         [0005]    In another aspect of the present invention, a delivery catheter used for female sterilization with an atraumatic ball tip and an opening in the catheter side wall is disclosed. The delivery catheter includes a hinge that will yield or bend under a certain load to prevent injury to the uterine wall or fallopian tube. The side wall opening is angled to allow proper placement of a plug into the fallopian tube for occlusion of the fallopian tube. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  shows a sectional view of the delivery catheter illustrating the main components of the delivery catheter. 
           [0007]      FIG. 2  shows the distal portion of the delivery catheter. 
           [0008]      FIG. 3  shows a perspective view of the major components of the sheath retraction mechanism. 
           [0009]      FIG. 4  illustrates the delivery catheter with the plug ejection mechanism as it is configured prior to ejection of the plug. 
           [0010]      FIG. 5  illustrates the delivery catheter as it is configured after the plug ejection mechanism has been activated and the plug has been uncovered. 
           [0011]      FIG. 6  shows the distal portion of the delivery catheter of  FIG. 5  after the plug ejection mechanism has been activated and the plug has been uncovered. 
           [0012]      FIG. 7  illustrates a delivery catheter with the plug ejection mechanism adapted for use with the catheter construction depicted in our prior U.S. Pat. No. 6,309,384. 
           [0013]      FIG. 8  shows a delivery catheter with the latch release button disposed in the proximal portion of the handle. 
           [0014]      FIG. 9  shows a solenoid-operated version of the sheath retraction system of  FIG. 3  which may be used in the delivery catheters of  FIGS. 1 ,  2 ,  4  and  5 . 
           [0015]      FIG. 10  illustrates a catheter body with a distal ball tip, adjacent hinge and side wall opening. 
           [0016]      FIG. 11  illustrates the hinge and ball tip bending under pressure to prevent injury to the tissue. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]      FIG. 1  is a sectional view of the delivery catheter  1  illustrating the main components of delivery catheter  1 . The delivery catheter  1  comprises an ergonomic handle  2  housing a sheath retraction mechanism  3 , a cable  4  with an electrical connector  5 , a catheter body or shaft  6 , a sheath  7  and a plug  20  (not visible in the view) disposed within the wounding segment  8 . The sheath  7  comprises a tube slidably disposed within the catheter body  6 . The sheath extends proximally to the handle and distally from the distal end of the catheter body  6 . The handle comprises a housing  9  which contains the sheath retraction mechanism  3  and support structures for the catheter body, connectors and other components, and provides an ergonomic handgrip for the clinician. The cable and connector are suitable for connection to a power source and control system, which is operable to provide power to the wounding segment.  FIG. 2  shows the distal portion of the delivery catheter, including the distal portion of the sheath which protrudes distally from the distal end of the catheter body  6 . The distal portion of the sheath  7  comprises the wounding segment  8  coupled to a tapered atraumatic distal tip  12 . A plug opening slit  13  is located on one side of the sheath approximately 3 mm proximal to the end of the distal tip. Electrodes  14 ,  15 ,  16  and  17  on the outer surface of the wounding segment  8  are operable to lightly wound the ovarian pathway as described in Harrington, U.S. Pat. No. 6,309,384. A push rod assembly  18  is disposed within the sheath and catheter body. The distal tip  19  of the push rod is located within the internal diameter of the sheath  7  and against the proximal end of the plug  20 . The push rod assembly maintains the plug in position within the ovarian pathway while the sheath  7  and wounding segment are pulled proximally within the catheter body  6  when the plug ejection mechanism is operated. 
         [0018]      FIG. 3  shows a perspective view of the major components of the sheath retraction mechanism. The sheath retraction mechanism comprises a chassis  21  and a sliding hub  22  that is slidably engaged with the chassis. The chassis is fixedly attached to the housing of the handle shown in  FIG. 1 . The proximal end  23  of the sheath  7  is longitudinally fixed to the sliding hub. (The pushrod  18 , hidden in this view, extends proximally beyond the proximal end of the catheter body, and is fixed to the chassis at the proximal end of the chassis.) Rail guides in the form of ridges or extensions  24   d  and  24   p  coupled to the sliding hub fit within rail slots  25  of the chassis, such that the sliding hub is slidably secured within the chassis. A spring  26  is operably coupled to the sheath through a piston rod  27  which is coupled and longitudinally fixed to the sliding hub. The spring is disposed within a dashpot  28  that comprises a cylinder  29  with a fluid-filled chamber  30 . (The fluid within the chamber may be a liquid or gel having sufficient viscosity to regulate the expansion of the spring  26  and retract the sheath smoothly. Suitable fluids include materials such as silicone oil.) The spring engages a piston  31  slidably disposed within the chamber. The rod  27  is coupled to the piston at the rod&#39;s proximal end and coupled to the sliding hub at the rod&#39;s distal end. (Perforations  32  in the piston allow movement through the fluid within the chamber.) A latch  33  is used to hold the sliding hub in the distal position, and thus hold the spring in a compressed position, as shown in  FIG. 3 . The latch is U-shaped with a base  34  and extensions  35  that extend downward into interfering relationship with the distal rail guide  24   d . The yoke is slidably disposed about the chassis and may slide up and down relative to the chassis and sliding hub. The extensions contain a channel  36  (shown in phantom) sized and dimensioned to accommodate the distal rail guides  24   d . When the yoke is in an up position the yoke channel is misaligned with the rail guide, preventing proximal movement of the sliding hub. When the yoke is moved down such that the channel  36  is aligned with the rail guide, the system is unlatched and the sliding hub and sheath are pulled proximally by the expanding spring. (The components shown in this view are symmetrical about the long axis of the device, so that the hidden side of sheath retraction mechanism is identical to the illustrated view, but the device need not be symmetrical. Also, the dashpot assembly illustrated has the spring disposed within the fluid chamber of the dashpot, but the spring may be located in any other convenient position in the system (for example, proximal to the sliding hub).) 
         [0019]      FIG. 4  illustrates the delivery catheter  1  with the plug ejection mechanism as it is configured prior to ejection of the plug. Here, the spring  26  is compressed within the cylinder  29 . The sliding hub  22  is in a distal position within the handle  2 . The yoke  33  is holding the sliding hub  22  in this position. A latch release button  37  is positioned above the yoke  33  in such a manner so as to impinge upon the yoke  33  when the push-button  37  is depressed. The channel  36  is misaligned with the rail guide  24  and the rail slot  25 . The push rod assembly  18  is longitudinally fixed relative to the chassis  21  and handle. The sliding hub  22  is coupled to the sheath  7  at its proximal end by boss  38  (which is fixed to the proximal end of the sheath and captured within the sliding hub) but is not attached to the underlying push rod  18 . 
         [0020]      FIG. 5  shows the plug ejection mechanism after as it is configured after it has been activated and the plug  20  has been uncovered. In this view, the push-button  37  has been depressed and has moved the yoke  33  downward. When the button  37  is depressed and the yoke  33  is in a down position, the channel  36  is aligned with the rail guide  24  and the rail slot  25 . Thus, the rail guide  24  is able to slide within the channel  24  along the slot  25  when the release button  37  is depressed. This allows the spring  26  to expand and force the piston, rod, sliding hub and sheath proximally relative to the chassis and handle, while the push rod  18  is held in place relative to the withdrawn sheath. Withdrawal of the sheath  7  within the catheter body  6  deposits the plug from the distal tip of the catheter without moving the plug relative to a wounded segment of the ovarian pathway after initial positioning (and also without moving the catheter body relative to the patient). 
         [0021]    To provide feedback to the physician that the plug ejection is complete, a first contact  39  is deposed on a rail guide and a 30 second contact  40  is mounted on the wall of the handle or otherwise fixed relative to the handle and/or chassis. An electrical circuit is closed as long as the first and second contacts remain in electrical communication with one another. 
         [0022]    Energy can be supplied to the wounding element while this electrical communication is maintained. When the sheath retraction mechanism  3  is activated, the sliding hub  22  is forced proximally (and the sheath  7  is retracted), and the first contact slides past the second contact. The first and second contacts are no longer in electrical communication with one another when the sliding block is in the proximal position within the handle. The loss of contact is sensed by the control system, which provides visual or audio indication to the clinician indicating that the sheath has been withdrawn. The control system may also be programmed such that it will not provide power to the wounding segment if contact between the two electrodes has been broken. In conjunction with the control system, which is programmed to provide appropriate interface indications and apply power only if the contacts are in electrical communication, this limits the possibility that doctor might try to insert a catheter that is not properly loaded, or which has been used or prematurely released. 
         [0023]      FIG. 6  shows the distal portion of the delivery catheter after the plug ejection mechanism has been activated and the plug is ejected. As illustrated in  FIG. 6 , the plug  20  is uncovered and released by the retraction of the sheath  7  over the plug  20  as it is held in position by the push rod  18 . 
         [0024]      FIG. 7  illustrates a delivery catheter with the plug ejection mechanism adapted for use with the catheter construction depicted in our prior U.S. Pat. No. 6,309,384. As shown in  FIG. 7 , the delivery catheter comprises a catheter body  43  with a wounding segment  44  comprising a short tubular sheath  45  slidably mounted within the distal tip  46  of the catheter. The distal tip of the catheter body extends over the proximal end of the tubular extension for a short length. Four electrodes  47 ,  48 ,  49  and  50  are disposed along the outer surface of the wounding segment and wrap around the catheter. 
         [0025]    One or more foam plugs  51  are stored within the catheter body, and are shown housed within the wounding segment. A push rod  52  is disposed within the catheter body  43 , fixed longitudinally within the catheter body at a point proximal to the wounding segment which permits adequate pullback of the wounding segment sheath  45  to uncover and release the plug, in contrast to the holding rod of  FIGS. 1 through 5  which extends into the handle to a fixation point proximal to the proximal end of the catheter body. Unlike the sheath shown in  FIGS. 1 through 5 , the sheath  45  of  FIG. 7  does not fully extend to the chassis  21  and is not directly coupled to the sliding hub  22 . Instead, a pullwire  53  is secured to the proximal end of the sheath  45  and wounding segment by attachment of the boss  54  on the distal end of the pullwire  53 . The pullwire  53  extends proximally from the wounding segment to the hub and is longitudinally fixed to the sliding hub  22 . The dashpot  28 , latch  33 , and pushbutton  37  are arranged as described above. When the plug ejection mechanism is activated, the pullwire and the sheath  45  are retracted proximally as the sliding hub  22  slides proximally within the chassis  21 . Thus, various arrangements of the translating components and fixed components of the system may be employed in the plug ejection mechanism. 
         [0026]    In use, the clinician places the distal end of the catheter system at the appropriate location within the ovarian pathway of the patient, using appropriate visualization and manipulation the catheter with the handle. Thereafter, the clinician will operate the control system of the system to apply appropriate energy to the ovarian pathway proximate the wounding segment. 
         [0027]    Thereafter, the clinician, holding the catheter system in one hand or both hands, need only depress the push-button to release the plug into the wounded segment of the ovarian pathway. Using the configuration described above, all necessary manipulations may be accomplished one-handed, leaving the clinician&#39;s other hand free to manipulate the control system or a hysteroscope. 
         [0028]    If it is desired to configure the device so as to inhibit one-handed operation, the device may be configured as shown  FIG. 8 , which illustrates a configuration of the handle and sheath retraction mechanism with the push-button disposed in the proximal portion of the handle, thereby encouraging two-handed use of the device. The delivery catheter of  FIG. 8  includes the catheter shaft or body  6 , a sheath  7  and housing  9 . The plug ejection mechanism  3  is contained within the handle. A release button  37  operably coupled to the plug ejection mechanism is disposed in the proximal portion  60  of the handle. The shaft retraction mechanism is rearranged, with the dashpot  28  placed distally of the sliding hub  22 , and the spring disposed to push, rather than pull, the sliding hub proximally. 
         [0029]    With this arrangement, with the housing held most conveniently, the push-button is disposed proximally of the clinician&#39;s preferred hand (the hand  61  used to manipulate the catheter), thus encouraging or requiring that the clinician use his other hand  62  to depress the push-button. This delivery catheter may require two hands to operate. The plug ejection mechanism may also be modified to use a spring that pulls on the piston rather than push against the piston in order to retract the sheath. 
         [0030]    The sheath may be pushed or pulled, so long as the sheath is retracted within the body. The shaft retraction system can also be modified so that the clinician need not manually depress a push-button to force the latch downward.  FIG. 9  shows a solenoid-operated version of the sheath retraction system of  FIGS. 1 through 5 . In  FIG. 9 , a solenoid  63  is operably coupled to the yoke and is used in place of a release button. Other components of the plug ejection mechanism, including the chassis  21 , the sliding hub  22 , the dashpot  28  and the latch  33  are arranged as shown in  FIG. 4  or  FIG. 8 . In this device, the solenoid is placed in electrical communication with a control system. The control system is programmed to activate the plug ejection mechanism upon receipt of appropriate input from the operator, or immediately after the wounding energy has been applied. The solenoid operates to push the yoke downward to align the channels with the rail guide of the sliding hub and thereby permit proximal movement of the sliding hub. This “no-hands” configuration has the benefit that it can be controlled by the control system, and the control system can be further programmed to energize the solenoid (and eject the plug) only after the wounding segment has been operated, thereby avoiding inadvertent ejection or release without the requisite wounding steps. 
         [0031]      FIG. 10  illustrates a catheter body or shaft  6  with a distal ball tip  12 , adjacent hinge  64  and side wall opening. In  FIG. 10 , the catheter body  6  has a distal end and a proximal end and an elongated portion in between the distal and proximal ends. A handle  2  is located at the proximal end of the catheter body  6 . The catheter body  6  is tapered at the distal end forming the distal ball tip  12 . The ball tip  12  is configured to navigate through the uterus and the fallopian tube such that the plug may be inserted into the fallopian tube to sterilize the patient. The distal ball tip  12  is spherical in shape. The distal ball tip  12  has a diameter in a range from about 0.02 inches to about 0.05 inches and more preferably from about 0.03 inches to about 0.04 inches. The ball tip  12  may be either hollow or solid but it is preferably solid. 
         [0032]    Thermoplastic elastomers are used to form the catheter body  6  including the distal tip  12  and adjacent hinge  64 . The catheter body  6  may be formed using a single thermoplastic elastomer material or different thermoplastic elastomer materials may be used to form the different portions of the catheter body  6 . 
         [0033]    Polyurethane is the preferred material to form the catheter body. Examples of other suitable materials that may be used to form the catheter body are polyvinyl chloride, polyamide, polypropylene, polyethylene, Pebax® and nylon. 
         [0034]    The hardness of the material selected to form the catheter body  6  is an important feature of the invention. Polyurethane having a durometer in the range of about 35 to about 72 durometer on the Shore D hardness scale is preferred. Polyurethane having a durometer in the range of about 42 to about 62 on the Shore D hardness scale is most preferred. 
         [0035]    There are several different embodiments disclosed for the hinge  64 . In all embodiments, however, the hinge  64  is designed to operate such that the distal ball tip  12  bends or yields under high loads to prevent the puncture of the fallopian tube or uterine wall.  FIG. 11  illustrates the adjacent hinge  64  and ball tip  12  bending under pressure to prevent injury to the epithelium. If the hinge  64  does not cause the ball tip  12  to bend under pressure, the ball tip  12  may puncture the patient&#39;s epithelium during a procedure. Because the hinge  64  causes the ball tip  12  to yield, the ball tip  12  and the catheter  1  may be used to navigate through the fallopian tubes, uterus or other vessel of the body without causing any injury to the patient. 
         [0036]    In one embodiment of the invention, the hardness of material selected to form the distal ball tip  12  is greater than that of the hardness selected for the adjacent hinge  64 . For example, the hinge  64  may be composed of polyurethane having a durometer of  42  while the ball tip  12  may be composed of polyurethane having a durometer of  55 . Because the hinge  64  has a softer durometer than the ball tip  12 , the ball tip  12  will yield or bend at the hinge in response to a high pressure load. This prevents the ball tip  12  from puncturing or damaging the epithelium when the catheter is inserted into the uterus and the fallopian tube. 
         [0037]    In another embodiment of the invention, the geometry of the hinge  64  is altered to comprise a groove. In this embodiment, the hinge may be made of the same material having the same durometer as the ball tip. A groove is cut around the circumference of the catheter body. The groove may be V-shaped or any other geometry suitable to achieve the purpose of the hinge. The size of the groove corresponds to the failure or bending of the hinge and ball tip under a certain pressure. For example, a larger groove or a groove that has a larger depth will yield under lower pressures. Smaller grooves or grooves that have a smaller depth will yield only under higher pressures. The groove may be formed by removing material from the catheter body after the catheter is formed at the location desired of the hinge. 
         [0038]    Alternatively, the hinge may be formed by forming a catheter body  6  having a thinner wall at the desired location for the hinge  64 . The thinner wall at the location of the hinge  64  on the catheter body  6  ensures that the hinge  64  will yield under pressure and cause the distal tip  12  to bend. The hinge  64  may also be formed by simply heat treating the catheter body  6  at the desired location for the hinge  64 . Heat treating the thermoplastic elastomer material selected for the catheter body  6  will alter the yield strength at the location of the hinge  64 . 
         [0039]    The side wall opening  13  is located along the elongated catheter body  6 . The implant or contraceptive plug is discharged through the side wall opening  13 . An important feature of the side wall opening  13  is that it allows the implant or contraceptive plug to exit the catheter body  6  without disturbing the distal ball tip  12 . In one embodiment, the side wall opening  13  is angled such that the implant exits the side wall of the catheter body  6  at the proper orientation and in a concentric fashion to occlude the fallopian tube. 
         [0040]    The side wall opening  13  may be shaped in a variety of different ways. In one embodiment, the opening  13  may be in the shape of simple slit across the catheter body. The slit must be sized large enough for the implant or plug to be discharged through the slit. For example, an effective length for the slit may be about 3 mm. One advantage of the slit configuration for the opening is that the slit returns to a closed position after the implant is discharged and the catheter body may be used a second time. The slit opening is particularly beneficial when using the catheter body to implant occluding plugs into the fallopian tubes. 
         [0041]    In another embodiment, the side wall opening may take the form of a flap rather than a slit. The flap may be different sizes and geometries. The size and shape of the flap must be sized to accommodate the push rod discharging the implant through the flap. For example, the flap may be configured as an M-cut made in the catheter body. A flap may be more appropriate than a slit depending on the size and shape of the plug or implant that is being used with the catheter. 
         [0042]    The plug ejection mechanism and sheath retraction system can be adapted to deliver other contraceptive devices, occlusive devices intended for other lumens of the body, and other implants. Thus, while the preferred embodiments of the devices and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the inventions. Other embodiments and configurations may be devised without departing from the spirit of the inventions and the scope of the appended claims.