Abstract:
An implantable vessel occlusive device and method for occluding a vessel are described, for example to occlude the urethra or bladder neck. The devices and methods described utilize an occlusive member connected to a control mechanism. The occlusive member is reversibly changed from a non-occlusive condition to an occlusive condition, for example by depressing an activation button contained within a resilient, elastomeric cover surrounding the control mechanism. In the occlusive position, an initial tension is applied to the occlusive member through a tensioning suture. The tension is translated into an occlusive pressure applied to the urethra or bladder neck that is sufficient to prevent urinary leakage. The non-occlusive position can be obtained by depressing the de-activation button. The occlusive member is constructed to allow elution of drugs, such as may be required to combat infection or tissue encapsulation from its surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/461,290 entitled “TAPE MECHANICAL OCCLUSIVE DEVICE” filed on Jan. 18, 2011, which is herewith incorporated by reference in its entirety. 
    
    
     This invention was made with government support under SBIR Grant Number 1 R43 DK076397 01A1 awarded by the National Institutes of Health. The government has certain rights in the invention. 
    
    
     FIELD 
     This document generally relates to an occlusive device for occluding fluid conveying vessels in the body and particularly, but not by way of limitation, to a urethral occlusive device for preventing urinary incontinence. 
     BACKGROUND 
     Vessel occlusive devices are well known and commonly referred to as “artificial sphincters.” They are installed within the body to aid or replace the natural sphincter of the body. For example, men can become urinary incontinent for example following surgeries to remove cancerous prostates. Women can become incontinent for example due to the pelvic trauma caused during childbirth and due to a laxity of the pelvic muscles occurring due to aging. Further, men and women may be rendered incontinent due to for example trauma, infection and/or birth defects. 
     Urethral occlusive devices can be used to restore urinary continence to patients with urinary control problems caused by various neurological diseases, surgical procedures, spinal cord injury, etc. Other occlusive devices include those used for contracting the bowel to prevent fecal leakage, for contracting the esophagus to prevent gastro-esophageal reflux, or those used in the area of gastric banding for restricting the stomach in treatment for obesity, and occlusion of the seminal vesicles or fallopian tube to control male and/or female fertility, of which there are needs that exist for commercial devices that can be used in such applications. 
     In particular, devices utilizing hydraulic sphincters or cuffs described in U.S. Pat. Nos. 3,863,622; 4,222,377, 4,412,530 and 4,878,889, have been used to provide urethral occlusion. To use these types of devices, the patient squeezes a control pump, which transfers fluid from a cuff to a pressure regulating balloon. The balloon forces the fluid through a fluid restrictor and back into the cuff to reestablish an occlusive urethral pressure within 3-5 minutes. These urethral occlusive devices are complicated to implant. One problem with hydraulic sphincters or cuffs is that they often do not apply uniform pressure on the urethra. As the cuff or sphincter is inflated, it folds or changes its shape, often in a non-uniform manner, thereby exerting uneven occlusive force on the urethra. This can result in urinary leakage, urethral erosion, or the urethra tissue being worn away after extensive use. 
     In other examples, the American Medical Systems, Inc. AUS 800 is a totally implantable hydraulic sphincter implanted in both males and females experiencing urinary incontinence and has been on the market for more than 35 years. The AUS 800 and its predecessors are described in U.S. Pat. Nos. 3,863,622, 4,222,377, 4,412,530 and 4,878,889. The AUS 800 may have a silicone pressure regulating balloon implanted in the prevesical space, a silicone control pump implanted in the scrotum or labia and a silicone urethral occlusive cuff wrapped around the bulbous urethra in males or bladder neck in females. Each component may be filled with saline or radiopaque contrast media, and tubing emanating from each component may be routed between incisions for appropriate connections. The device can be deactivated for a period of approximately 6 weeks to allow tissue healing to proceed and urethral edema to subside. At activation, the control pump may be squeezed sharply to unseat a poppet and open operational fluid flow paths. The patient is taught to operate the device by squeezing the control pump through the scrotal or labial skin. This action can transfer fluid from the cuff to the pressure regulating balloon. The balloon can force the fluid through a fluid restrictor and back into cuff to reestablish an occlusive urethral pressure within 3-5 minutes. The AUS 800 can be complicated to implant and prone to fluid leakage, and may cause urethral atrophy and erosion. The complexity of its implantation is partly due to the requirement to intra-operatively fill and assemble its three components. The AUS 800 often fails due to wear in its componentry which leads to fluid leakage and post-operative infections. Urethral atrophy and erosion sometimes occur and are suspected to be due to the crenate shape of its occlusive cuff. Post-operative infection requiring explanation of the device also is a frequent complication. Despite these drawbacks, the AUS 800 is the only commercially available artificial urinary sphincter currently. The AUS 800 is available with a number of occlusive pressure ranges with 61-70 cm H 2 O being the pressure most frequently selected. 
     U.S. Pat. Nos. 5,704,893 and 6,074,341 discuss other types of urethral occlusive devices, which are entirely implantable artificial urinary sphincters. These artificial urinary sphincters are one-piece devices that do not require saline filling or intra-operative assembly, but where depression of a deactivation plunger, for example through the scrotal skin, causes a urethral occlusive sheath to expand and remove occlusive pressure from the urethra to allow normal urination. Depression of an activation button allows the occlusive sheath to contract and reapply urethral pressure to prevent urethral leakage. While such devices provided significant improvement in vessel occlusion, implantation in humans was impeded by growth of tough, fibrous tissue around the device, due to the natural defenses of the human body, which over time prevented expansion of the occlusive sheath. 
     SUMMARY 
     Generally, vessel occlusive devices are described and methods for occluding a vessel or vessels that convey fluid in humans and animals are described. Vessel occlusive devices as described herein generally include an occlusive member and a control mechanism for actuating the occlusive member into occluding and non-occluding positions. 
     One embodiment of the vessel occlusive device may include an outer sheath. One embodiment of the outer sheath may be a resilient tubular structure. The outer sheath may have a space inside the outer sheath, and the outer sheath is configured to retain liquid inside the space. At least a portion of the outer sheath is configured to encircle a fluid conveying body vessel. An inner occlusive tape is disposed through the space of the outer sheath. One end of the occlusive tape is fixed to an end of the outer sheath, and the other end of the inner occlusive tape is freely movable relative to the outer sheath. A control mechanism is connected to the free end of the inner occlusive tape. When the control mechanism applies a tension to the inner occlusive tape, the inner occlusive tape applies a pressure to the portion of the outer sheath encircling the fluid conveying body vessel; and when the control mechanism releases the tension from the inner occlusive tape, the inner occlusive tape releases the pressure to the portion of the outer sheath encircling the fluid conveying body vessel. 
     Another embodiment of the vessel occlusive device may have an inner occlusive tape that has a varied width from the first end to the second end of the inner occlusive tape. One embodiment of the inner occlusive tape may have a varied width that is tapered. A preset portion of the varied width may encircle a circumference of a vessel when implanted. 
     In some embodiments of the vessel occlusive device, the size of the portion of the outer sheath that is configured to encircle a fluid conveying body vessel may be adjusted to accommodate the anatomically variable structures of the body vessel. In some embodiments, an outer surface of the outer sheath may have a sizing band. The sizing band may have a plurality of locking detents. The locking detents may engage to a locking clip of the occlusive device. By locking the outer sheath at different locking detents, the size of the portion of the outer sheath that encircles the body vessel may be adjusted. 
     In yet another embodiment of the vessel occlusive device, a bleed valve may be connected to one end of the outer sheath and in fluid communication with the space of the outer sheath. The bleed valve may have an open position and a closed position; and the open position is configured to allow air to escape out of the space of the outer sheath and the closed position is configured to be water tight. 
     A method of applying an occlusive pressure to a tubular body passage may include implanting an occlusive device inside a body. The occlusive device may have an occlusive member that has an outer sheath and an inner occlusive tape. The inner occlusive tape may be disposed through a space of the outer sheath. One end of the occlusive tape is fixed to an end of the outer sheath, and the other end of the inner occlusive tape is freely movable relative to the outer sheath. A portion of the outer sheath may be wrapped at least partially around a vessel. A liquid may be added to the space of the outer sheath and the outer sheath can retain the fluid in the space. A tensioning force may be applied to one end of the inner occlusive tape so that the inner occlusive tape applies a pressure to the portion of the outer sheath wrapping the tubular body passage. 
     The inner occlusive tape may have varied width along its length. A method of applying an occlusive pressure to a tubular body passage may also include the step of positioning a predetermined portion of the varied width of the inner occlusive tape so that the predetermined portion of the varied width encircle a circumference of a vessel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings, which are not necessarily drawn to scale, illustrate generally, by way of example, but not by way of limitation, various embodiments discussed below. 
         FIG. 1A  is a perspective view of an embodiment of a mechanical occlusive device encircling a vessel in a closed activated state. 
         FIG. 1B  is a perspective view of an embodiment of a mechanical occlusive device encircling a vessel in an open deactivated state. 
         FIGS. 2A and 2B  are perspective views of an occlusive member of an occlusive device.  FIG. 2A  shows an inner surface of the occlusive member that is configured to be in contact with a vessel when in use.  FIG. 2B  shows an outer surface of the occlusive member that is configured to be away from the vessel when in use. 
         FIG. 3A  is a partial side cross-section view of an embodiment of an occlusive member encircling a vessel that is in an open deactivated state. 
         FIG. 3B  is a partial side cross-section view of an embodiment of an occlusive member encircling a vessel that is in a closed activated state. 
         FIG. 4A  is a front cross-section view of an embodiment of an occlusive member encircling a vessel that is in an open deactivated state. 
         FIG. 4B  is a front cross-section view of an embodiment of an occlusive member encircling a vessel that is in a closed activated state. 
         FIG. 5  is a perspective view of a portion of an embodiment of an occlusive member showing a coil and an inner occlusive tape. 
         FIGS. 6A and 6B  are side views of an embodiment of an occlusive device.  FIG. 6A  shows an occlusive member of the occlusive device configured to fit a larger vessel than the vessel that the occlusive device in  FIG. 6B  is configured to fit. 
         FIGS. 7A and 7B  are perspective views of portions of an occlusive device.  FIG. 7A  shows a clip prior to engagement of an occlusive member.  FIG. 7B  shows the clip following the engagement of the occlusive tape. 
         FIG. 8  is a side view of an embodiment of an inner occlusive tape. 
         FIG. 9  is a side elevation view of an embodiment of an occlusive device and a syringe. 
         FIGS. 10A and 10B  are front views of a bleed valve that is connected to one end of an occlusive member.  FIG. 10A  shows the bleed valve in an open position, and  FIG. 10B  shows the bleed valve in a closed position. 
         FIGS. 11A and 11B  are elevation views of a control mechanism. 
         FIGS. 12A to 12C  are partial sectional views of an embodiment of a control mechanism, and including a plunger dome as part of the cover of the control mechanism. 
         FIG. 13  is a schematic view of a motorized vessel occlusive device. 
         FIGS. 14A and 14B  are schematic views of an embodiment of an occlusive device having a sling occlusive member.  FIG. 14A  shows the sling occlusive member in non-occluding position, and  FIG. 14B  shows the sling occlusive member in an occluding position. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown, by way of illustration, specific embodiments in which inventive concepts may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that the embodiments may be combined or used separately, or that other embodiments may be utilized and that structural and procedural changes may be made without departing from the spirit and scope of the inventive concepts. The following detailed description provides examples, and the scope of the present invention is defined by the claims to be added and their equivalents. 
     It should be noted that references to “an,” “one,” or “various” embodiments in this disclosure are not necessarily to the same embodiment, and such references contemplate more than one embodiment. 
     The terms “above,” “on,” “under,” “top,” “bottom,” “up,” “down,” “horizontal,” and “vertical” and the like used herein are in reference to the relative positions of the vessel occlusive device, and its constituent parts, in use when oriented as in  FIGS. 1-14 . 
     In this document, the terms “occlude,” “occluding,” “occlusive” or “occlusion” respectively mean partially or completely occlude, partially or completely occluding, partially or completely occlusive, or partial or complete occlusion. 
     In this document, the terms “encircle,” “surround” or “enclose” respectively mean partially or completely encircle, surround or enclose. 
     This document generally discusses, among other things, vessel occlusive devices and methods for occluding a vessel or vessels that convey fluid in humans and animals. As one particular example, the vessel occlusive devices and methods herein discuss applications that involve occluding a urethra by implanting an artificial device in a human body for providing an incontinent patient protection against urine leakage and for providing control over the patient&#39;s voiding function. However, it is to be understood that the present devices and methods may be employed in other areas, including, but not being limited to, fecal incontinence, gastro-esophageal reflux disease, and gastric banding for weight loss, bile duct flow control, male and/or female fertility control through reversible occlusion of the seminal vesicles or fallopian tube, or to provide general occlusion or support of body vessels for other purposes. Generally, it will be appreciated that the discussion below can apply to various vessels and/or body parts that can convey fluid and may have a need to be restricted or occluded by an occlusive device. It is also to be understood that the occlusive devices described herein may include multiple pieces or components operatively connected to each other, and that they may be either partially or entirely implantable in the body of humans or animals. 
     Vessel occlusive devices as described herein generally include an occlusive member and a control mechanism for actuating the occlusive member into occluding and non-occluding positions. The occlusive member can be configured to apply a constant force on a targeted vessel when the occlusive member is actuated in the occluding position. 
     Methods for controlling fluid flow in a fluid conveying body vessel include implanting a vessel occlusive device inside the body of a subject in need. The step of implanting may include surrounding at least a portion of the fluid conveying vessel and actuating the vessel occlusive device to apply an occlusive force and occlude the fluid conveying vessel. The occlusive force may be released when fluid flow is to be allowed through the fluid conveying vessel. The step of releasing occlusive force may include actuating the vessel occlusive device to a deactivated/non-occluding position. The vessel occlusive device may be then reactuated into the activated/occlusive position when fluid flow is no longer to be allowed. In one embodiment, a constant force can be applied on the fluid conveying vessel during at least one of the implanting and the reactuating steps. 
     An embodiment of the vessel occlusive device  1  for implantation in males is shown in  FIGS. 1A and 1B . In one embodiment, the occlusive device  1  is implanted entirely and no pre- or post-implantation assembly is required. An occlusive member  2  may encircle a urethra  3 . A control mechanism  4  may be connected to the occlusive member  2  through a conduit  9 . The conduit  9  may be flexible to accommodate bodily movement by the human implant subject. In some embodiments, a portion of the conduit  9  may encircle a close wound metal coil structure (e.g. coil structure  15  described further below), which is flexible and can be bent. 
     The control mechanism  4  may have an activation button  5  and a deactivation button  6  that are encapsulated by a silicone boot  7  which may incorporate a needle port or septum  8 . The control mechanism boot  7  may be infused through the septum  8  with normal saline or radiopaque solutions intended to allow visualization of the otherwise non-radiopaque occlusive member  2 . 
     The occlusive device  1  may be implanted in the scrotum in males and the labia or abdominal wall in females. Before the implantation, the occlusive member  2  may be filled with a fluid and the occlusive member  2  may be configured to retain the fluid inside the occlusive member  2 . The occlusive member  2  may be implanted in a deactivated/non-occlusive condition to a patient for approximately  6  weeks post-operatively to facilitate healing and allow pain and edema to subside. Following this period, the occlusive device may be activated by depressing an activation button  5  through the intact scrotal skin. In so doing, the occlusive member  2  may contract to apply a preset occlusive pressure, for example about 50-80 cm H 2 O, to the urethra  3 , which can occlude the urethra  3 . The patient is then free to depress a deactivation button  6  to release the tension of the occlusive member  2  and cause the occlusive member  2  to return to the deactivated/non-occlusive condition, and allow unobstructed voiding. To re-establish urethral occlusive pressure and continence, the patient can push the activation button  5  again. 
     An embodiment of the occlusive member  2  is shown in  FIGS. 2A and 2B  in its extended condition prior to implantation. The occlusive member  2  may have an outer sheath  12  that is connected to conduit  9 . The outer sheath  12  may have a thin wall structure. The thin wall structure may be flexible and elastic. The outer sheath  12  may generally have two surfaces: inner surface  11  and outer surface  17 . The inner surface  11  of the outer sheath  12  may be flat and configured to be in contact with a body vessel such as a urethra when in use. The inner surface  11  can contract the body vessel when in use. The outer surface  17  of the outer sheath  12  may be configured to be away from the body vessel when in use. The outer surface  17  may be configured to have a flexible sizing band with locking detents  18  situated along the length of the outer sheath  12 , which may be used to size the occlusive member  2  to fit a specific vessel circumference encountered during implantation (see below for more detail). 
     As shown in  FIGS. 3A and 3B , when implanted, the outer sheath  12  of the occlusive device  1  may encircle a urethra  3 . The outer sheath  12  may have a space  200  inside the outer sheath  12 . In one embodiment, the outer sheath  12  may be a tubular structure. An inner occlusive tape  13  is disposed through the outer sheath  12  in the space  200 . One end of the inner occlusive tape  13  may be fixed to a terminal end  14  of the outer sheath  12 , while the other end of the inner occlusive tape  13 , proximal end  10  of the occlusive tape  13 , may be free to translate back and forth inside the outer sheath  12  relative to a proximal end  16  of the outer sheath  12 . When a tension is applied to the proximal end  10  of the inner occlusive tape  13 , the inner occlusive tape  13  can cause the outer sheath  12  to collapse along its length and presses the outer sheath  12  against the urethra  3  so as to occlude the urethra  3 . The proximal end  16  of the outer sheath  12  may be connected to conduit  9  to provide a receptacle through which the inner occlusive tape  13  may be pulled. A flexible metal coil structure  15  may be connected to the proximal end  16  of the other sheath  12 . The coil structure  15  may also extend into the conduit  9 . The coil structure  15  is flexible and can be bent to allow the occlusive device  1  to conform to anatomical variants and to flex and bend freely with bodily movement. The proximal end  10  of the inner occlusive tape  13  may go through the coil structure  15 . The coil structure  15  may be a closed wound structure to provide axial structural stiffness. The stiffness of the coil structure  15  may prevent compression of the inner occlusive tape  13  by the surrounding bodily tissues, which may hinder movement of the inner occlusive tape  13 . The conduit  9  and the outer sheath  12  may be configured to be water tight. The conduit  9  may be in fluid communication with the space  200  so that a liquid may flow between the conduit  9  and the space  200 . 
     The internal space  200  may be air-filled as received prior to implantation. Placing an air-filled, closed structure within the body can create an osmotic pressure gradient across the membrane of the structure. If the membrane is permeable or semi-permeable as most thermoplastic and thermoset materials are, there can be a net loss of air within the structure and a vacuum may be created. This vacuum may cause collapsing deformable, sealed structures within the body and a similar collapse in an occlusive structure may prevent intended function. Therefore, prior to implantation, the internal space  200  may be filled with an isotonic medium such as normal saline or isotonic radio-opaque solution intended to aid in radiographic visualization of the implanted device. Filling the internal space  200  with an isotonic medium may also prevent fluid exchange between the internal space  200  and the surrounding body tissue when in use. 
     The occlusive device  1  may have two states when in use: a deactivated/non-occlusive state and an activated/occlusive state. In the deactivated state, there is no tension applied to the proximal end  10  of the inner occlusive tape  13 . As a result, the inner occlusive tape  13  cannot press the outer sheath  12  and cannot occlude the urethra  3 . In an activated state, a tension is applied by a control mechanism (e.g. control mechanism  4 ), which is connected through the conduit  9  to the proximal end  10  of the inner occlusive tape  13 . This tension draws the proximal end  10  toward the control mechanism. As a result, the outer sheath  12  collapses along its length, and therefore presses against the urethra  3  so as to occlude the urethra  3 . Because the space  200  may be filled with a liquid, when the outer sheath  12  collapses along its length in the activated state, the shape of a cross section of the outer sheath  12  may change. 
     Referring to  FIGS. 4A and 4B , the deactivated and activated states and the change of the shape of the cross section of the occlusive member  2  including the outer sheath  12  are further illustrated. As shown in  FIG. 4A , when there is no tension applied to the inner occlusive tape  13 , the occlusive device is in the deactivated state, and the outer sheath  12  may not have enough pressure to occlude the urethra  3 . Therefore, the urethra  3  is open and allows a fluid to flow through. When a tension is applied to the inner occlusive tape  13 , the device is in an activated state, and the outer sheath  12  may collapse along its length as shown in  FIG. 3B , which also leads to the shape of the cross section of the space  200  of the outer sheath  12  to change (as shown in  FIG. 4B ) compared to the shape of the deactivated state as shown in  FIG. 4A . As a result, the outer sheath  12  may be pressed against the urethra  3  by the occlusive tape  13  so as to occlude the urethra  3  and prevent fluid flowing through the urethra  3 . 
     The outer surface  17  of the outer sheath  12 , which is opposite to the surface of the outer sheath  12  that contracts the urethra  3 , may be configured to have a flexible sizing band. The sizing band may encircle the entire length of the outer sheath  12 , or it may encircle only a portion of the outer sheath  12 . 
     The outer sheath  12  may be made of a thin resilient member so that the outer sheath  12  may return to the shape of the deactivated state when the tension applied to the inner occlusive tape  13  in the activated state is released. The outer sheath  12  may be flexible so that it does not hinder the ability of the inner tape  13  to compress the urethra  3  under a tension. 
     The inner occlusive tape  13  may be constructed from expanded polytetrafluoroethylene (ePTFE) with an internodal distance (porosity) of &lt;30 μ and the tape  13  may have a thickness within the range of 0.010″ to 0.025″ and a width of 7 mm to 10 mm. The length of the tape  13  may be sufficient to encircle urethras within the range of 3.0 cm to 5.5 cm. The outer sheath  12  may also be constructed from ePTFE so as to allow movement of the inner occlusive tape  13  through the outer sheaths  12  with minimized frictional resistance. The outer sheath  12  may also be coated with a thin, pliable layer of silicone, polyurethane or other thermoplastic or thermoset material on its surface to prevent the movement of bodily fluids and bacteria into the interior of the device and to prevent tissue ingrowth into the pores of the outer sheath  12 . The outer sheath  12  may have an internodal distance and wall thickness within the same ranges as the inner occlusive tape  13 . However, the width of the tubular outer sheath  12 , when laid flat, may be generally greater than the width of the inner occlusive tape  13  to allow the outer sheath  12  to collapse to a small enough diameter to occlude the urethra  3  which it encircles, as shown in  FIGS. 4A and 4B . 
     Referring to  FIG. 5 , one embodiment of the coil structure  15  and the occlusive tape  13  are illustrated. For clearer illustration, the coil windings of the coil structure  15 , which winds around a longitudinal axis of the occlusive tape  13 , are not shown. The longitudinal axis runs through the proximal end  10  of the occlusive  13  toward the control mechanism (the arrow in  FIG. 5  illustrates the direction toward the control mechanism). As shown in  FIG. 5 , the cross section of the coil structure  15  may vary along its length to provide an appropriate combination of flexibility/stiffness and geometry shape into which the geometry of the inner occlusive tape  13  may be accepted. One such geometric variant may be a rectangular cross-section appropriate to accept at least a portion of the proximal end  10  of the flat inner occlusive tape  13  which transitions into a circular cross-section through which a cable  100  joining the inner occlusive tape  13  to a control mechanism may pass. The coil structure  15  may have a transitional section  150  between the portion of the rectangular cross-section and the portion with the circular cross-section. The circular cross-section portion may be more uniformly flexible in all directions than the rectangular cross-section portion. This may enable the control mechanism to be placed more freely during the implantation procedure. Many other geometric variations may also be employed. 
     Another embodiment of the occlusive device provides a means by which the occlusive member  2  may be sized to a specific urethral circumference encountered during implantation. In such circumstance, there may be no need to measure the urethra at the time of implantation and select from a wide variety of devices sized for specific urethral circumference ranges. As shown earlier in  FIG. 2B  as well as in  FIGS. 6A and 6B  herewith, the outer surface  17  of the occlusive member  2  may be have a flexible sizing band with a plurality of locking detents  18  situated along its length. When the occlusive member  2  is placed during the implantation procedure, a portion of the occlusive member  2  may be conformed to encircle the urethral surface. To ensure that the portion of the occlusive member  2  fits as closely as possible to the urethra  3  and prevents the occlusive member  2  from being released from this position following implantation, a metal clip  19  that is attached to the occlusive member  2  near the proximal end  16  of the outer sheath may engage the locking detent(s)  18  of the flexible sizing band. The clip  19  may be locked in place to maintain a predetermined circumference encircled by the occlusive member  2  during the implantation. By positioning the clip  19  to engage a different locking detent, the circumference of the portion of the occlusive member  2  that conformed to encircle the urethral surface may be adjusted 
     One embodiment of the clip  19  and locking mechanism is depicted in  FIGS. 7A and 7B .  FIG. 7B  (as well as  FIG. 1A ) shows the clip  19  in a closed or locked position.  FIG. 7A  shows the clip  19  in an open position. The clip  19  may be positioned close to the proximal end  16  of the outer sheath  12  that is connected to the conduit  9 . The clip  19  may have an integral spring biased to holding the clip  19  in its locked position. Alternately, the clip  19  may be hinged on one end to facilitate easy opening during the implantation procedure. The terminal end  14  of the outer sheath  12  may pass underneath the clip  19  and the clip  19  may be locked during an implantation procedure. Further, locking the clip  19  in place also serves to fix the portion of the inner occlusive tape that is enclosed by the terminal end  14  of the outer sheath  12  to the terminal end  14  as shown in  FIGS. 3A and 3B . The inner occlusive tape  13  within the outer sheath  12  is still free to move relative to the outer sheath  12  from the clip  19  to the proximal end of the inner occlusive tape, as shown in  FIGS. 3A and 3B . 
     The flexible sizing band may be molded from implant grade silicone rubber of sufficient durometer (30-80 durometer) to prevent deformation of the locking detents  18  in use. Polyurethane or other flexible, biocompatible thermoplastics or thermoset materials may be used as a substitute for silicone rubber. The clip  19  may be wound 316L stainless steel, MP35N (Nickel-Cobalt alloy) wire or other biocompatible, rigid thermoplastic or metal. The coil  19  may be covered by silicone coated thin walled ePTFE or molded silicone sheath conforming to the coils geometry to prevent the incursion of bodily fluids and tissue ingrowth into the occlusive device&#39;s interior. 
     When encircling the urethra  3 , an axial tension applied to the inner occlusive tape  13  by the control mechanism can apply a pressure to the urethra  3 . The pressure applied to the urethra  3  is affected by the surface area of the inner occlusive tape  13  contracting the urethra  3  and the axial tension applied to the inner occlusive tape  13  by the control mechanism. The pressure applied to the urethra  3  by the inner occlusive tape  13  may be characterized by the LaPlace relationship which allows calculation of pressures generated in cylindrical bodies as follows:
 
 P=T/RW  
         where P=pressure within the cylindrical body (urethra)
           T=tension applied circumferentially about the urethra   R=Radius of the urethra   W=Width of the tensioning member as measured along the axis of the urethra   
               

     From this equation, it must be noted that when the width of the occlusive tape is constant, for equal tension T circumferentially applied to the urethra, a smaller urethral circumference can result in a higher urethral pressure P within the cylindrical body of the urethra and larger urethral circumferences can result in lower urethral pressures P. It has been demonstrated that the range of urethral circumferences found in men who are candidates for implantation is from about 3.5 cm to about 4.5 cm. Using a tape design with a single constant width for this circumferential range may cause urethral pressures to fall outside of the pressure range of about 50-80 cm H 2 O that is required to occlude the urethra effectively if the urethral circumference is large. 
     To minimize the pressure variation due to the difference in the urethral circumference, as shown in  FIG. 8 , the occlusive tape  13  may generally incorporate a varied width along the length of the tape  13 . In one embodiment, the width of the tape  13  may have a tapered profile, which has width W 1  and W 2  at the ends of the occlusive tape  13  respectively and W 1  is larger than W 2 , In one embodiment, the proximal end  10  of the occlusive tape  13  that is connected to the control mechanism (the arrow in  FIG. 8  shows the direction leading to the control mechanism) has the width W 1 . When sizing the occlusive member  2  as shown in  FIG. 6A  to accommodate a larger urethra circumference, the locking clip  19  is shifted toward the thinner end of the tape  13  (W 2 ). This effectively decreases the composite width of the tape  13  and increases the urethral pressure. When sizing the occlusive member  2  as shown in  FIG. 6B  to accommodate a smaller urethra circumference, the locking clip  19  is shifted toward the wider end of the tape  13  (W 1 ). This effectively increases the composite width of the tape  13  and decreases the urethral pressure. Experimental data suggests that a tape width range (W 1 to W 2 ) of about 10 mm to about 3 mm can provide the appropriate urethral pressures. 
     As discussed earlier and shown in  FIG. 9 , the outer sheath  12  may be filled with a liquid before implantation. To fill the outer sheath  12 , a small hypodermic needle (for example, a 21-23 Gauge needle) attached to a saline filled syringe  21  may be inserted through a septum  8  of a control mechanism  4  as seen in  FIG. 9 . In some embodiments, the internal of the control mechanism  4 , the conduit  9  and the outer sheath  12  are in fluid communication; therefore the saline solution can flow into the outer sheath  12  through conduit  9 . 
     Now refer to  FIGS. 10A and 10B , an embodiment of a bleed valve  20  that can be used to facilitate the liquid filling of the outer sheath is described. The bleed valve  20  may be incorporated into the terminal end  14  of the outer sheath of the occlusive member and may also be integral to the molded flexible sizing band affixed to the occlusive member. The space  200  of the outer sheath  12  as shown in  FIG. 3A  may be in fluid communication with the bleed valve  20  as shown in  FIGS. 10A and 10B . A metal spool valve  22  may be inserted into the body  23  of the bleed valve  20  and may be configured to allow air to escape from the space  200  of the outer sheath  12  as shown in  FIG. 3A  through a bleed valve port  24  as seen in  FIG. 10A . When a liquid is injected into the space  200  through the septum  8  as shown in  FIG. 9 , air inside the space  200  can escape through the bleed valve port  24  as shown in  FIG. 10A , When all air has been removed from the space  200 , the liquid can be seen to leak from this open bleed valve port  24 . The needle may then be removed from the control mechanism  4  and the spool valve  22  may be depressed to insert it fully within the body  23  of the bleed valve  20  as seen in  FIG. 10B . This action can seal the bleed valve port  24  to prevent the further leakage of solution from or leakage of air back into the outer sheath  12 . 
     The spool valve  22  may be machined or molded from a wide variety of materials including 316L stainless steel, MP35N (Nickel-Cobalt alloy) wire or other biocompatible, rigid thermoplastic or metal. The body  23  may be molded of a resilient material such as silicone rubber. The mating channel of the body  23  may be of a smaller diameter than the spool valve  22  to form a compressive air tight and water tight seal between the two structures. 
     Movement and the tension applied to the occlusive member may be generally supplied by a control mechanism implanted in the scrotum of the male or in the abdominal wall of the female or in a miniaturized version within the labia of the female. Generally, depression of an activation button on the control mechanism through the intact skin may cause a spring force to retract the occlusive member and apply a constant pressure to the urethra which it encircles. Depression of a deactivation button that may be also located on the control mechanism may release the spring force from the occlusive member and removes pressure from the urethra. 
     Embodiments of various control mechanisms are described in great detail in U.S. Pat. No. 8,007,429 VESSEL OCCLUSIVE DEVICE AND METHOD FOR OCCLUSING A VESSEL. One of these embodiments is described below. 
     As shown in  FIGS. 11A and 11B , a cable and pulley system may be used as a control mechanism. The pulley  27  may rotate counter clockwise when a user depresses a deactivation button  26  exiting the control mechanism  4 . A cable  28  may wrap around a small pulley  29  at one end and the circular base of the deactivation button  26  at its other end as shown in  FIGS. 11A and 11B . As the deactivation button  26  advances, the distance that the cable  28  can be pulled can be doubled relative to the distance that the deactivation button  26  is depressed. 
       FIGS. 12A ,  12 B and  12 C show side sectional views of the control mechanism as shown in  FIGS. 11A and 11B . Particularly, an embodiment of a boot or cover  7  for at least the deactivation button  26  is illustrated, and a lever  31  and a détente pin  30  are also illustrated. When the deactivation button  26  is depressed to its full extent, The détente pin  30  contained within the deactivation button  26  can engage the lever  31 , which may prevent the deactivation button  26  from returning to its original extended position. The lever  31  may be biased by a spring  32  captured between the lever  31  and a silicone rubber boot  7  surrounding the control mechanism. As the deactivation button  26  is depressed, the deactivation button dome  33  of the flexible silicone boot  7  may deform with the force applied to it, but may rebound to its original shape when the force is removed. In this way, the occlusive sheath may be held in a condition which does not compress the urethra. Rebounding of the dome  33  may prevent the tissue capsule, which normally forms around any implanted device, from restricting movement of the deactivation button  26 . 
     When the patient desires to return to a continent state with the urethra compressed, the silicone boot  7  may be depressed over the lever  31  as shown in  FIG. 12C  (the arrow in  FIG. 12C  shows the direction of the depression). This can disengage the lever  31  from the détente pin  30 , allowing the deactivation button  26  to return to an extended position under the bias of a constant force spring  34  nested within the pulley  27 . 
     With reference to  FIG. 13 , the mechanical control mechanism  4 , described above, may be configured as a closed loop, electro-mechanical, and servo-control system. This system may include an occlusive member  2  and a conduit  9  connected to the occlusive member  2 , a pulley  35 , a rotary actuator such as a motor  36 , a micro-processor based control mechanism  37 , a power supply  38  and separate urethral  39  and abdominal  40  pressure sensing elements. In this embodiment, the rotary actuator  36  may turn the pulley  35  which in turn may take up and apply load to a traction sutures  41  to occlude the urethra  3 . It is appreciated that a linear actuator such as a lead screw may be used in place of a rotary actuator. 
     In a resting state, the pulley  35  may be biased so that the occlusive tape  2  applies about 0 to about 20 cm H 2 O pressure to the urethra. This pressure range is generally adequate to prevent urinary leakage during normal, unstressful activities. Urethral pressure may be continuously or intermittently monitored by a urethral pressure sensing element  39  situated between the occlusive member  2  and the outer surface of the urethra  3 . Abdominal or bladder pressure may be monitored continuously or intermittently by a pressure sensor  40  implanted within the abdominal cavity, within the abdominal wall, within the bladder and/or within the bladder wall. 
     As bladder filling occurs, bladder pressure can increase within the range of about 20-60 cm H 2 O. Sensing this pressure increase, the abdominal/bladder pressure sensor  40  may signal the control mechanism  4  to turn the motor  36  on and cause the pulley  35  to rotate and affect a rise in urethral pressure. When the urethral pressure sensing element  39  detects that urethral pressure is about 60-80 cm H 2 O, the motor  36  may be turned off and the pulley  35  may be held in position to prevent any further pressure increase or decrease. Once the abdominal/bladder pressure reduces to about 20 cm H 2 O or less, the control mechanism  4  may again signal to allow the rotary actuator  36  to reverse the direction and reduce the tension on the traction sutures  41  until urethral pressures between about 0 and about 20 cm H 2 O are achieved. 
     Stressful events such as coughing, sneezing, laughing, etc. can often cause abdominal/bladder pressures spikes in excess of 60 cm H 2 O. Pressure rise times of 35 msec and elevated pressure durations of approximately 100 msec have been recorded. 
     Sensing these pressure levels, the control mechanism  4  may cause the rotary actuator  36  to turn on and rotate the pulley  35  to affect a rise in urethral pressure of as much as 120 cm H 20 O. When abdominal/bladder pressure declines to about 20 cm H 2 O or less, the control mechanism  3  allows the rotary actuator  36  to reverse direction and reduce tension on the traction sutures  41  until urethral pressures between about 0 and about 20 cm H 2 O are achieved. 
     When the user wishes to void urine, a switch may be manually activated through the skin. This action can cause the pulley  34  to free-wheel, reducing traction suture  41  tension until a 0 cm H 2 O urethral pressure is achieved, The user then voids urine through the unobstructed urethra  3 . The user may then manually depress the switch again to return the device to its resting mode or the device will be programmed to automatically return to its resting mode within 3-5 minutes. 
     With the reference to  FIGS. 14A and 14B , the occlusive device may also be configured to provide adjustable support to tubular body organs without totally encircling them. An example of this usage may be a sling configuration of the occlusive tape  43  to provide urethral support in both males and females. In this configuration, the degree of support may be adjusted to accommodate varying anatomical conditions and degrees of urinary incontinence. The control mechanism  4  used to adjust the degree of support may be one of the mechanical variants as shown in  FIGS. 11 and 12 , or the electro-mechanical variant shown in  FIG. 13 . The ends  42  of the elevating tape  43  may be fixed to the pubic bone or endopelvic facsia by sutures or screws. As load applied to the traction sutures  41  by the control mechanism  4 , the elevating tape  43  may elevate the urethra, thereby compressing it from the underside and increasing the intra-urethral pressure to prevent leakage. 
     It is to be understood that the above detailed description is intended to be illustrative, and not restrictive. Other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled,