Patent Publication Number: US-2012029269-A1

Title: Apparatus and method for inserting an adjustable implantable genitourinary device

Description:
RELATED APPLICATIONS 
     This application is a continuation of and claims the benefit of priority under  35  U.S.C. § 120  to U.S. patent application Ser. No. 12/838,927, filed Jul. 19, 2010, which is a continuation of and claims the benefit of priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 11/331,838, filed Jan. 13, 2006, now issued as U.S. Pat. No. 7,771,346, which is a continuation of and claims the benefit of priority under  35  U.S.C. § 120  to U.S. patent application Ser. No. 10/167,563, filed Jun. 11, 2002, now issued as U.S. Pat. No. 7,014,606, which is a continuation of and claims the benefit of priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 09/415,801, filed Oct. 11, 1999, now issued as U.S. Pat. No. 6,419,624, all of which are incorporated herein by reference in their entireties. 
     This application is a continuation-in-part of and claims the benefit of priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 10/932,414, filed Sep. 2, 2004, which is a continuation of and claims the benefit of priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 10/673,028, filed Sep. 26, 2003, now abandoned, which is a continuation of and claims the benefit of priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 10/167,565, filed Jun. 11, 2002, now issued as U.S. Pat. No. 6,645,138, which is a divisional of and claims the benefit of priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 09/345,884, filed Jul. 1, 1999, now issued as U.S. Pat. No. 6,419,701, which is a continuation of and claims the benefit of priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 08/928,946, filed Sep. 12, 1997, now issued as U.S. Pat. No. 5,964,806, which is a continuation-in-part of and claims the benefit of priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 08/873,444, filed Jun. 12, 1997, now issued as U.S. Pat. No. 6,045,498, all of which are incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to implantable medical devices and in particular to implantable medical devices for coaptation of a body lumen. 
     BACKGROUND OF THE INVENTION 
     Various implantable devices, such as inflatable/distensible medical devices, are known in which the distensible medical devices are implanted into the tissue of a human to treat urinary incontinence. These devices have typically relied upon restricting or constricting the urethra of the patient to maintain continence. 
     U.S. Pat. No. 4,733,393 to Haber et al. is an attempt at such a proposed device. U.S. Pat. No. 4,733,393 relates to a hypodermically implantable genitourinary prosthesis which provides an extensible, inflatable tissue expanding membrane to be located in proximal urethral tissue to add bulk to these tissues for overcoming urinary incontinence by localized increase in tissue volume. 
     U.S. Pat. No. 4,802,479 to Haber et al. is an attempt at an instrument for dispensing and delivering material to an inflatable membrane of a genitourinary prosthesis within the tissues of a patient for overcoming urinary incontinence. U.S. Pat. No. 4,832,680 to Haber et al. relates to an apparatus for hypodermically implanting a genitourinary prosthesis comprising an extensible containment membrane for retaining a fluid or particulate matter which is injected from an external source. 
     U.S. Pat. No. 5,304,123 to Atala et al. relates to a detachable membrane catheter incorporated into an endoscopic instrument for implantation into the suburethral region of a patient. Also, U.S. Pat. No. 5,411,475 to Atala et al. discusses a directly visualized method for deploying a detachable membrane at a target site in vivo. U.S. Pat. No. 5,830,228 to Knapp et al. relates to a method and system for deployment of a detachable balloon at a target site in vivo. 
     Once inflated, these devices maintain pressure on the urethra of the patient in an attempt to assist with continence. However, these devices are prone to being under or over inflated at time of implant, leading to undesirable postoperative results. For example, if the devices are overinflated it may cause the urethra to be restricted too tightly, and the patient is at risk for retention, a condition where the patient cannot pass urine. Such a condition could lead to kidney damage, necessitating major corrective surgery or at minimum use of self-catheterization to empty the bladder on a regular basis thus increasing the risk of urinary tract infection. 
     Furthermore, once these devices have been implanted within the patient, the only means of removing them in the event of a postoperative problem or device malfunction is through major surgery. Also, the devices are not secured within the tissues of the patient, so there is the possibility of the devices migrating back along the pathway created in inserting them, a problem which has been noted with prior art devices. Thus, an important medical need exists for an improved implantable device for treating urinary incontinence. 
     SUMMARY OF THE INVENTION 
     The present invention provides an implantable device and a method for its use in restricting a body lumen. In one embodiment, the body lumen is a urethra, where the implantable device is used to coapt the urethra to assist the patient in urinary continence. The implantable medical device has the advantage of being adjustable both at the time of implantation and postoperatively. This postoperative adjustability of the implantable medical device allows a physician to regulate the amount of pressure applied to the urethra to ensure continence of the patient and to minimize iatrogenic effects. 
     In one embodiment, the present subject mater includes an implantable device assembly for controllable coaption of a body lumen. The implantable device assembly includes an implantable device which includes an adjustable element and a tubular elongate body. The adjustable element includes a continuous wall, including an inner surface defining a chamber. The tubular elongate body includes a peripheral surface, a proximal end and a distal end, where the peripheral surface is connected to and sealed to the adjustable element. The tubular elongate body further includes at least a first interior passageway which extends longitudinally in the tubular elongate body from a first opening at the proximal end to a second opening in fluid communication with the chamber of the implantable device. This allows for adjustably expanding or contracting the adjustable element by applied flowable material introduced through the first opening. The implantable device assembly also includes a sheath, where the sheath includes a wall having an inner surface which defines a channel through which at least a portion of the implantable device can pass. 
     In one embodiment, the implanted device is inserted into body tissue by passing the device through the sheath. The sheath is first inserted into the tissue of the patient and then the implanted device is moved through the channel of the sheath. In one embodiment, the implanted device is moved through the sheath through the use of a push rod, where the push rod is inserted into the first interior passageway. As the push rod is inserted into the first interior passage way it comes into contact with a closed end distal to both the first opening and second opening of the first interior passage way. Force can then be applied to the push rod to move the implanted device at least partially through the channel of the sheath. 
     In an alternative embodiment, the tubular elongate body includes a second interior passageway which extends longitudinally along at least a portion of the tubular elongate body from an inlet to a closed end. The second interior passageway is of sufficient diameter to receive the push rod which contacts the closed end to allow force applied to the push rod to move the implanted device at least partially through the channel of the sheath. 
     In an additional embodiment, the implantable device assembly can further include a sleeve having a longitudinal slot, where at least a portion of the implanted device is housed in the volume defined by the sleeve. In one embodiment, the sleeve and implanted device are passed through the sheath so as to extend the adjustable element past the distal end of the sheath. The adjustable element is then expanded so that contact is made with the tissue. In one embodiment, the sheath is withdrawn from the body, after which the sleeve is then either passed around a portion of the implanted device or a portion of the implanted device deforms to allow the implanted device to pass through the sleeve. In an alternative embodiment, the sleeve is withdrawn from the body, after which the sheath is passed around a portion of the implanted device. 
     In an additional embodiment, the implantable device includes a rear port element coupled to the proximal end of the tubular elongate body. In one embodiment, the rear port element is releasably attached to the tubular elongate body. The rear port element including a cavity in fluid communication with the first opening of the first interior passageway. This allows for fluid volume passed through the rear port element to either expand or contract the size of the adjustable element. In one embodiment, the rear port element has an elastic septum to receive a needle through which flowable material can pass to expand or contract the adjustable element. 
     The sheath of the present subject matter also includes a first portion and at least one of a second portion, where the second portion is of a lesser strength compared to the first portion. In one embodiment, the second portion extends longitudinally along the wall to allow for the wall of the sheath to be separated. In one embodiment, the second portion of the wall includes scorings extending longitudinally along the wall which create a weak area over which the sheath can be torn. In an additional embodiment, the wall of the sheath can include two scorings extending longitudinally along the wall to allow for the sheath to be separated into two pieces. Alternatively, the sheath can include a slit through the wall, where the slit extends longitudinally along the wall. 
     In an additional embodiment, the implanted device further includes a tip suitable to penetrate tissue. In one embodiment, the tip is positioned, or is formed, at the distal end of the tubular elongate body. Alternatively, the distal end of the push rod forms the tip, where the tip is exposed at the distal end of the tubular elongate body when the distal end of the push rod passes through an outlet end in the second interior passage way. 
     Finally, an important feature of the implantable device of the present invention relates to the adjustable element or membrane which is accessible for subsequent adjustment in volume through the rear port element located under a patient&#39;s skin, remotely from the adjustable element. Another important feature of the present invention over the prior art devices is the convenient in vivo postoperative adjustability of both pressure and size of the adjustable element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of an implantable device assembly according to one embodiment of the present subject matter, where a sheath is shown in cross-sectional view to reveal an implantable device; 
         FIG. 2  is a schematic cross-sectional view of the implantable device assembly according to one embodiment of the present subject matter; 
         FIG. 3  is a schematic cross-sectional view of the implantable device assembly according to one embodiment of the present subject matter; 
         FIG. 4A  is a schematic of the implantable device assembly according to one embodiment of the present subject matter; 
         FIG. 4B  is a schematic of the implantable device assembly according to one embodiment of the present subject matter; 
         FIG. 5  is a schematic of an implantable device according to one embodiment of the present subject matter; 
         FIG. 6A  is a schematic cross-sectional view of the implantable device assembly according to one embodiment of the present subject matter; 
         FIG. 6B  is a schematic end view of the implantable device assembly according to one embodiment of the present subject matter; 
         FIG. 7A  is a schematic view of a sheath according to one embodiment of the present subject matter; 
         FIG. 7B  is a schematic view of a sheath according to one embodiment of the present subject matter; 
         FIG. 7C  is a schematic view of a sheath according to one embodiment of the present subject matter; 
         FIG. 8A  is a schematic view of a sheath according to one embodiment of the present subject matter; 
         FIG. 8B  is a schematic view of a sheath according to one embodiment of the present subject matter; 
         FIG. 9  is a schematic view of a sheath according to one embodiment of the present subject matter; 
         FIG. 10  is a schematic view of a sheath according to one embodiment of the present subject matter; 
         FIG. 11  is a schematic view of a sheath according to one embodiment of the present subject matter; 
         FIG. 12A  is a schematic cross-sectional view of the implantable device assembly according to one embodiment of the present subject matter; 
         FIG. 12B  is a schematic cross-sectional view of the implantable device assembly according to one embodiment of the present subject matter; 
         FIG. 13  is a schematic of an implantable device according to one embodiment of the present subject matter; 
         FIG. 14  is a schematic of an implantable device according to one embodiment of the present subject matter; 
         FIG. 15  is a schematic of an implantable device assembly according to one embodiment of the present subject matter; 
         FIG. 16A  is a schematic of an implantable device according to one embodiment of the present subject matter; 
         FIG. 16B  is a schematic of an implantable device according to one embodiment of the present subject matter; 
         FIG. 16C  is a schematic of an implantable device according to one embodiment of the present subject matter; 
         FIG. 16D  is a schematic of an implantable device according to one embodiment of the present subject matter; 
         FIG. 17  is a method according to one embodiment of the present subject matter; 
         FIG. 18  is a method according to one embodiment of the present subject matter; 
         FIG. 19  is a schematic of an implantable device according to one embodiment of the present subject matter; and 
         FIG. 20  is a schematic of an implantable device according to one embodiment of the present subject matter. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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 the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice and use the invention, and it is to be understood that other embodiments may be utilized and that logical, and structural changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense and the scope of the present invention is defined by the appended claims and their equivalents. 
     The present subject matter describes embodiments of an implantable device assembly and/or an implantable device for restricting a body lumen. In one embodiment, the present subject matter is for treating urinary incontinence by implanting at least one of the implantable devices adjacent the urethra. In an alternative embodiment, the present subject matter is for treating ureteral reflux of a patient by implanting at least one of the implantable devices adjacent one or both ureter proper. Additionally, the present subject matter is useful in treating urinary stress incontinence resulting from male post radical prostatectomy, esophageal reflux, fecal incontinence or vascular restriction. 
     Implantable devices designed for treating urinary incontinence are typically referred to as a genitourinary prosthesis. Many designs for genitourinary prosthesis have been proposed. In one such proposed embodiment, the genitourinary prosthesis comprises an implantable device which includes a rear port element coupled to a tubular elongate body and an adjustable element, where the adjustable element has a chamber designed to receive a measured supply of flowable material introduced through the rear port element to inflate the prosthesis. One such description of a genitourinary prosthesis is also provided in a U.S. patent application Ser. No. 08/928,946, entitled “ADJUSTABLE IMPLANTABLE GENITOURINARY DEVICE” filed Sep. 12, 1997, by Burton et al., which is hereby incorporated by reference in its entirety. 
     In treating urinary incontinence, the prosthesis is delivered within the body to a location that is typically within the periurethral tissue and adjacent to the urethra to enable a patient to overcome urinary incontinence by means of increasing both localized tissue volume and passive occlusive pressure upon the urethral mucosa. The implantable device of the present subject matter is useful for accomplishing this objective, while the implantable device assembly of the present subject matter is useful in delivering the implantable device to a desired location within the body of the patient. 
     Referring now to  FIG. 1 , there is shown one embodiment of an implantable device assembly  100  according to the present subject matter. In one embodiment, the implantable device assembly is for delivering into a body an implantable device  110  for the controllable coaption, or restriction, of a body lumen. In one embodiment, the implantable device  110  is for treating ureteral reflux of a patient by implanting at least one of the implantable device  110  adjacent one or both ureter proper. In an alternative embodiment, the implantable device  110  is for treating urinary incontinence by implanting at least one of the implantable device  110  adjacent the urethra. 
     In  FIG. 1 , the implantable device  110  is shown to include an adjustable element  120  and a tubular elongate body  130 . In one embodiment, the adjustable element  120  includes a continuous wall, including an inner surface defining a chamber. The tubular elongate body  130  includes a peripheral surface  140 , a proximal end  150  and a distal end  160 , where the peripheral surface  140  is connected to and sealed to the adjustable element  120 . The implantable device  110  is shown positioned within a sheath  170 , where the sheath  170  includes a wall  180  having an inner surface  184  which defines a channel  188  through which at least a portion of the implantable device  110  can pass. In the embodiment shown in  FIG. 1 , a cross sectional view of the sheath  170  is shown so as to reveal the implantable device  110  positioned at least partially within the channel  188 . 
     Referring now to  FIG. 2 , there is shown a schematic cross-sectional view of the implantable device assembly  200  according to one embodiment of the present subject matter. An implantable device  202  is shown to include an adjustable element  204  and a tubular elongate body  206 . In one embodiment, the adjustable element  204  includes a continuous wall  208 , including an inner surface  210  defining a chamber  212 . The tubular elongate body  206  includes a peripheral surface  214 , a proximal end  216  and a distal end  218 . The adjustable element  204  has at least one opening through the continuous wall  208  to which the peripheral surface  214  is connected to and sealed to the adjustable element  204 . 
     In one embodiment, a first portion  220  and a second portion  222  of the inner surface  210  of the adjustable element  204  and the peripheral surface  214  are sealed using a chemical or polymer adhesive, such as silicone. In an alternative embodiment, the peripheral surface  214  is sealed to the first portion  220  and the second portion  222  using sonic welding techniques as are known in the art. The final result of bonding the first portion  220  and the second portion  222  of the inner surface  210  of the adjustable element  204  to the peripheral surface  214  of the tubular elongate body  206  is that a fluid tight bond or seal is created between the inner surface  210  of the adjustable element  204  and the peripheral surface  214  of the tubular elongate body  206 . 
     In one embodiment, the tubular elongate body  206  includes at least a first interior passageway  230  which extends longitudinally in the tubular elongate body  206  from a first opening  232  at the proximal end  216  to a second opening  234 . In one embodiment, the second opening  234  is in fluid communication with the chamber  212  of the implantable device for adjustably expanding or contracting the adjustable element  204  by flowable material introduced through the first opening  232 . In one embodiment, the fluid tight bonding at the first portion  220  and the second portion  222  allows for the chamber  212  to maintain pressure provided by the flowable material so that the size of the adjustable element  204  can be changed. 
     In one embodiment, the adjustable element  204  is constructed of a biocompatible resiliently elastomeric polymer or polymer blend of polyurethane, silicone, or the like. In this embodiment, the wall  208  stretches as the adjustable element  204  expands or contracts to a desired size. In an alternative embodiment, the continuous wall  208  is constructed of a biocompatible non-resilient polymer or polymer blend of polyethylene, polyethyleneterephthalate (PET), polyurethane, high modulus polystyrene, polyesteretherketone (PEEK), or other nonresilient polymers as known. In this embodiment, the continuous wall  208  of the adjustable element  204  expand to a predetermined shape. The adjustable element  204  is formed into a variety of shapes. In one embodiment, the outer surface of the continuous wall  208  generally defines a spherical shape. In an alternative embodiment, the outer surface of the continuous wall  208  generally defines an elongate body having semi-spherical end portions. 
     In one embodiment, the continuous wall  208  of the adjustable element  204  has a length and a diameter when inflated to operating volume, where the dimension of the length and diameter are selected in a range from one-half (0.5) centimeter to five (5) centimeters, where each of the length and diameter are selected independently. Alternatively, the adjustable element  204  can have a length and a diameter that are equal (length=diameter) so as to give a generally spherical shape to the adjustable element. In one embodiment, the adjustable element  204  has a spherical shape with a length and diameter of up to three (3) centimeters. In an alternative embodiment, the adjustable element  204  has a spherical shape with a length and diameter of up to one and one-half (1.5) centimeters. 
     Other configurations of length and diameter are possible so as to give adjustable elements  204  of different shapes. For example, the adjustable element can have an elliptical or kidney cross-sectional shape to facilitate at least partially surrounding the body lumen with the adjustable element, where the adjustable element is concave relative to the urethral lumen. The dimensions discussed for the adjustable element apply to all embodiments of the present subject matter. 
     In one embodiment, the first interior passageway  230  includes a closed end  240 , where the closed end  240  is positioned distal to both the first opening  232  and second opening  234 . The closed end  240  is of sufficient strength and hardness to receive a distal end  242  of a push rod  244 , where the closed end  240  transfers force applied at a proximal end  246  of the push rod  244  to the implantable device  202 . 
     In one embodiment, the first interior passageway  230  is of sufficient diameter to receive the push rod  244  which contacts the closed end  240  to allow force applied to the push rod  244  to move the implanted device  202  at least partially through a channel  250  of a sheath  254 . In one embodiment, the implantable device  202  is shown positioned within the sheath  254 , where the sheath  254  includes a wall  256  having an inner surface  260  which defines the channel  250  through which at least a portion of the implantable device  202  can pass. 
     In one embodiment, the push rod  244  has a length between a first end an a second end of the push rod in a range of ten (10) to forty (40) centimeters, a diameter of between 0.05 to 0.16 centimeters, where the diameter of the push rod will depend upon the construction material for the rod. In one embodiment, the push rod is made of stainless steel. Alternatively, the push rod is made of a plastic. In an additional embodiment, the push rod is made of a material having a yield strength greater than 12,000 psi. 
     In an additional embodiment, a detectable marker is imbedded in the implantable device  202 . For example, the detectable marker  270  is located at the distal end  218 , (e.g., the tip) of the tubular elongate body  206 . Alternatively, the detectable marker could be located in the continuous wall  208  of the adjustable element  204 . The detectable marker  270  allows the adjustable element  204  to be located and its shape to be visualized within the tissues of a patient using any number of visualization techniques which employ electromagnetic energy as a means of locating objects within the body. In one embodiment, the detectable marker  270  is constructed of tantalum and the visualization techniques used to visualize the adjustable element  204  are x-ray or fluoroscopy as are known in the art. In an additional embodiment, the sheath could also have a detectable marker, where the marker could be incorporated into, or on, the wall of the sheath. Alternatively, the entire sheath could be constructed so as to be radio opaque. 
     Referring now to  FIG. 3 , there is shown a schematic cross-sectional view of an implantable device assembly  300  according to one embodiment of the present subject matter. The implantable device assembly  300  is shown to include an implantable device  302 . The implantable device  302  includes an adjustable element  304  and a tubular elongate body  306 . In one embodiment, the adjustable element  304  includes a continuous wall  308 , including an inner surface  310  defining a chamber  312 . The tubular elongate body  306  includes a peripheral surface  314 , a proximal end  316  and a distal end  318 . In one embodiment, the peripheral surface  314  is connected to and sealed to the adjustable element  304 . 
     In one embodiment, a first portion  320  and a second portion  322  of the inner surface  310  of the adjustable element  304  is chemically bonded to the peripheral surface  314  of the tubular elongate body  306 . Alternatively, the first portion  320  and/or the second portion  322  of the inner surface  310  of the adjustable element  304  is mechanically and/or thermally welded to the peripheral surface  314  of the tubular elongate body  306 . The final result of bonding the first portion  320  and the second portion  322  of the inner surface  310  of the adjustable element  304  to the peripheral surface  314  of the tubular elongate body  306  is that a fluid tight bond or seal is created between the inner surface  310  of the adjustable element  304  and the peripheral surface  314  of the tubular elongate body  306 . 
     In one embodiment, the tubular elongate body  306  includes a first interior passageway  330  and a second interior passageway  332 . In one embodiment, the first interior passageway  330  extends longitudinally in the tubular elongate body  306  from a first opening  334  at the proximal end  316  to a second opening  336 . In one embodiment, the second opening  336  is in fluid communication with the chamber  312  of the implantable device for adjustably expanding or contracting the adjustable element  304  by flowable material introduced through the first opening  334 . In one embodiment, the fluid tight bonding at the first portion  320  and the second portion  322  allows for the chamber  312  to maintain volume provided by the flowable material so that the size of the adjustable element  304  can be changed. In one embodiment, the first interior passageway  330  includes a closed end  342 , where the closed end  342  is positioned distal to both the first opening  334  and second opening  336 . 
     In one embodiment, the second interior passageway  332  extends longitudinally along at least a portion of the tubular elongate body  306  from an inlet  344  to a closed end  346 . In one embodiment, the second interior passageway  332  is of sufficient diameter to receive a push rod  350  which contacts the closed end  346  to allow force applied to the push rod  350  to move the implanted device  302  at least partially through a channel  354  of a sheath  358 . In one embodiment, the closed end  346  is of sufficient strength and hardness to receive a distal end  352  of the push rod  350 , where the closed end  346  transfers force applied at a proximal end  354  of the push rod  350  to the implantable device  302 . In one embodiment, the force applied to the push rod  350  moves the implanted device  302  at least partially through the channel  354  of the sheath  358 . In one embodiment, the implantable device  302  is shown positioned within the sheath  358 , where the sheath  358  includes a wall  360  having an inner surface  362  which defines the channel  354  through which at least a portion of the implantable device  302  can pass. 
     In one embodiment, the second interior passageway  332  forms a portion of the tubular elongate body and extends from the inlet located at the proximal end  316  of the tubular elongate body  306  to the closed end  346  located at or proximal to the distal end  318  of the tubular elongate body  306 . Alternatively, the second interior passageway  332  extends longitudinally within the tubular elongate body  306  for only a portion of the overall length of the tubular elongate body  306 , as is shown in  FIG. 3 . 
     In an additional embodiment, a detectable marker is imbedded in the implantable device  302 . For example, the detectable marker  370  is located at the distal end  318 , (e.g., the tip) of the tubular elongate body  306 . Alternatively, the detectable marker could be located in the continuous wall  308  of the adjustable element  304 . The detectable marker  370  allows the adjustable element  304  to be located and its shape to be visualized within the tissues of a patient using any number of visualization techniques which employ electromagnetic energy as a means of locating objects within the body. In one embodiment, the detectable marker  370  is constructed of tantalum and the visualization techniques used to visualize the adjustable element  304  are x-ray or fluoroscopy as are known in the art. In an additional embodiment, the sheath could also have a detectable marker, where the marker could be incorporated into, or on, the wall of the sheath. Alternatively, the entire sheath could be constructed so as to be radio opaque. 
     Referring now to  FIG. 4A , there is shown a schematic of an implantable device assembly  400  according to one embodiment of the present subject matter. The present implantable device assembly  400  includes a sheath  404 , where the sheath  404  includes an elongate body  408  having a wall  412 . The wall  412  includes an inner surface  416  which defines a channel  420 . Included within the channel  420  is a sleeve  424 . The sleeve  424  includes a wall  430  having an outer surface  434  and an inner surface  438 . In one embodiment, the outer surface  434  and the inner surface  438  define an arc, or a partial cylinder or curved portion, of the wall  430 . In one embodiment, the arc of the wall  430  has a first dimension, such as a radius of curvature, with respect to the outer surface  434  of the wall  430  which permits the sleeve  424  to be positioned within the channel  420  of the sheath  404 . In addition, the first dimension of the sleeve is of a size which permits the sleeve  424  to move longitudinally within the channel  420  of the sheath  404  as is shown by arrow  440 . 
     In one embodiment, the sleeve  424  includes a channel  444  between a first edge  446  and a second edge  448  on the wall  430  of the sleeve  424 . In one embodiment, the first edge  446  and the second edge  448  of the channel  444  are parallel and extend longitudinally along the length of the sleeve  424 . Alternatively, the first edge  446  and the second edge  448  of the channel  444  converge or diverge, or both, longitudinally along the length of the sleeve  424 . The inner surface  438  of the sleeve  424  includes a second dimension, that is smaller than the first dimension of the outer surface, where the second dimension allows for a volume  460  to be defined. In one embodiment, the second dimension is of a radius for the inner surface of the arc defined by the wall  430 . The volume  460  is of sufficient size to permit the tubular elongate body and the adjustable element of the implantable device  462  to fit in the volume  460  defined by inner surface  438  of the sleeve  424 . In one embodiment, the implantable device  462  is of the type previously described. 
     The implantable device  462  is placed in the volume  460  defined by the sleeve  424  and the sleeve  424  and the implantable device  462  are then inserted into the channel  420  of the sheath  404 . Once inside the sheath  404 , the implantable device  462  and the sleeve  424  are advanced through the sheath  404  by applying force to either the sleeve  424  or to the implantable device  462 . In one embodiment, force applied to the sleeve  424  is provided by pushing or pulling at one or more points along the wall  430  of the sleeve  424 . When positioned in the sleeve  424  and the sheath  404 , the implantable device  462  has sufficient contact with the wall  430  of the sleeve  424  to prevent the adjustable member  472  of the implantable device  462  from slipping along the wall  430 . In other words, the dimensions of the outer surface of the adjustable member  472  and the inner surface  438  of the sleeve  424  provide for frictional forces sufficient to prevent the implantable device  462  to move relative to the sleeve  424  as the sleeve and implantable device are moved through the sheath. 
     Referring now to  FIG. 4B  there is shown an alternative embodiment of an implantable device assembly  473  according to one embodiment of the present subject matter. The present implantable device assembly  473  includes a sheath  474 , where the sheath  474  includes an elongate body  475  having a wall  476 . The wall  476  includes an inner surface  477  which defines a channel  478 . The implantable device assembly  473  further includes a sleeve  479 . The sleeve  479  includes a wall  480  having an outer surface  481  and an inner surface  482 . In one embodiment, the outer surface  481  and the inner surface  482  define an arc, or a partial cylinder or curved portion, of the wall  480 . In one embodiment, the arc of the wall  480  has a an inner diameter with respect to the inner surface  482  of the wall  480  which permits the sleeve  479  to be positioned around the peripheral surface  483  of the tubular elongate body  484  of the implantable device  462 . The sleeve  479  also includes a proximal end  484  and a distal end  485 , where the distal end abuts a ridge, or ledge, formed at the point where the peripheral surface  483  of the tubular elongate body is connected to and sealed to the adjustable element  472 . 
     The sleeve  479  allows for the implantable device  462  to be advanced through the sheath  474  by force applied at the distal end  485  of the sleeve  479 . Once the adjustable element  472  has been advanced past the distal end of the sheath  474 , the adjustable element  472  can be expanded (as shown) to fix the position of the implantable device  462  in the tissue of a patient. The adjustable element  472  is expanded by fluid volume introduced into the first interior passageway  487 . In one embodiment, once expanded, the sheath  474  is withdrawn from the body. The sleeve  479  is then either pulled, or slid, off the tubular elongate body  484 , or the tubular elongate body  484  is passed through the slot  488  of the sleeve  479 . Alternatively, once expanded, the sleeve is either pulled, or slid, off the tubular elongate body  484  or the tubular elongate body  484  is passed through the slot  488  of the sleeve  479 . The sheath  474  is then withdrawn from the body. 
     In one embodiment, the sleeve  479  has an inner diameter that is between zero (0) to five (5) percent larger than the diameter of the tubular elongate body  484 . Additionally, the sheath, as described in any of the present embodiments, has an inner diameter that is in a range of between 1.27 to 3.81 millimeters (or 0.050 inches to 0.150 inches). In one embodiment, the outer diameter of the sheath, as described in any of the present embodiments, has an outer diameter that is in a range of between 0.171 millimeters to 0.514 millimeters (0.0675 inches to 0.2025 inches), where the outer diameter is determined based on the type of material used to construct the sheath. In an alternative embodiment, the outer diameter of the sheath can be larger than 0.514 millimeters, where the final outer diameter of the sheath depends on the material used and the desired stiffness of the sheath. In one embodiment, the sheath is made of stainless steel. Alternatively, the sheath is made of a polymer, polymer blend and/or co-polymer, or a combination there of. For example, the sheath can be made of polyurethane or PEEK. 
     Referring now to  FIG. 5  there is shown a schematic cross-sectional view of an implantable device assembly  500  according to one embodiment of the present subject matter. As previously described, the implantable device assembly  500  includes an implantable device  502  having an adjustable element  504  and a tubular elongate body  506 , where the tubular elongate body  506  includes at least a first interior passageway  510  which extends longitudinally in the tubular elongate body  506  from a first opening  512  at the proximal end  516  to a second opening  520 , and where the implantable device  502  is shown positioned within a channel  524  of a sheath  526 . In one embodiment, the implantable device assembly  500  is similar to the implantable device assembly described from  FIG. 2 . 
     The implantable device assembly  500  further includes a rear port element  530 , where the rear port element  530  is coupled to the proximal end  516  of the tubular elongate body  506 . In one embodiment, the rear port element  530  is coupled to the proximal end  516  of the elongate body  506  using chemical adhesives, or alternatively, using sonic welding techniques as are known in the art. In an additional embodiment, the rear port element  530  and proximal end  516  are formed together in a polymer molding process, such as liquid injection molding, as are known in the art. 
     The rear port element  530  includes a cavity  536 , where the cavity  536  is in fluid communication with the first opening  512  of the elongate body  506 . In one embodiment, the rear port element  530  also includes an elastic septum  540  through which the cavity  536  is accessed, where the elastic septum  540  is a sealable after repeated pierces, for example, with a needle . In one embodiment, the elastic septum  540  is retained in the rear port element  530  by a clamp ring  550  located around the rear port element  530 . In one embodiment, the clamp ring  550  is made of a biocompatible material, such as, for example, titanium. In one embodiment, the elastic septum  540  is made of a biocompatible material, such as, for example, silicone or polyurethane. The rear port element  530  has an outer diameter defined by outer surface  554  of the rear port element  530 , where in one embodiment the rear port has an outer diameter of one (1) millimeter to ten (10) millimeters, (1) millimeter to six (6) millimeters, where four and one-half (4.5) millimeters is an possible diameter. The dimensions discussed for the rear port element apply to all embodiments of the present subject matter. 
     In one embodiment, the outer surface of the rear port element  530  and the adjustable element  504  are of a size (e.g., a diameter) that is smaller than an inner size (e.g., a diameter) of the channel  524  to allow the implantable device  502  to be moved longitudinally through the channel  524  of the sheath  526 . In an alternative embodiment, the rear port element  530  is constructed of at least one material flexible enough to allow the size of the rear port element  530  in its relaxed state to be compressed to a size sufficiently small so that the implantable device  502  can be moved longitudinally through the channel  524  of the sheath  526 . For the present embodiments, the tubular elongate body  506  has a stiffness sufficient to allow force applied at the proximal end of the tubular elongate body to move the implantable device at least partially through the channel of the sheath. In one embodiment, the stiffness of the tubular elongate body is determined based on the type of material used in constructing the tubular elongate body. Alternatively, support elements can be added to the tubular elongate body. For example, a metal coil can be placed longitudinally within the tubular elongate body to increase the stiffness of the tubular elongate body. 
     Once the implantable device  502  is positioned within a body, the adjustable element  504  is inflated by releasably connecting a flowable material source to the rear port element  530 . In one embodiment, the flowable material source includes a syringe with a non-coring needle, where the needle is inserted through the elastic septum  540 . A measured supply of fluid volume can be introduced into the implantable device, where the adjustable element  504  expands or contracts due to a volume of flowable material introduced into the cavity  536  of the rear port element  530  from the flowable material source. The adjustable element  504  is then used to at least partially and adjustably restrict the body lumen. Fluids suitable for infusing into the prothesis include, but are not limited to, sterile saline solutions, polymer gels such as silicone gels or hydrogels of polyvinylpyrrolidone, polyethylene glycol, or carboxy methyl cellulose for example, high viscosity liquids such as hyaluronic acid, dextran, polyacrylic acid, polyvinyl alcohol, or a radio-opaque fluid for example. Once the adjustable element  504  has been inflated, the needle is withdrawn from the septum of the rear port  530 . 
     In an additional embodiment, a detectable marker  570  is imbedded in the continuous wall of the adjustable element  504 . The detectable marker  570  allows the adjustable element  504  to be located and its shape to be visualized within the tissues of a patient using any number of visualization techniques which employ electromagnetic energy as a means of locating objects within the body. In one embodiment, the detectable marker  570  is constructed of tantalum and the visualization techniques used to visualize the adjustable element  504  are x-ray or fluoroscopy as are known in the art. 
     In an additional embodiment, a detectable marker is imbedded in the implantable device  502 . For example, the detectable marker  570  is located at the distal end  560 , (e.g., the tip) of the tubular elongate body  506 . Alternatively, the detectable marker could be located in the continuous wall of the adjustable element  504 . The detectable marker  570  allows the distal end  560 , or the adjustable element  504 , to be located and its shape to be visualized within the tissues of a patient using any number of visualization techniques which employ electromagnetic energy as a means of locating objects within the body. In one embodiment, the detectable marker  570  is constructed of tantalum and the visualization techniques used to visualize the distal end  560 , or the adjustable element  504 , are x-ray or fluoroscopy as are known in the art. In an additional embodiment, the sheath could also have a detectable marker, where the marker could be incorporated into, or on, the wall of the sheath. Alternatively, the entire sheath could be constructed so as to be radio-opaque. 
     Referring now to  FIG. 6A , there is shown a schematic cross-sectional view of an implantable device assembly  600  according to one embodiment of the present subject matter. As previously described, the implantable device assembly  600  includes an implantable device  602  having an adjustable element  604 , a tubular elongate body  606 , and a detectable marker  605  imbedded at the distal end of the tubular elongate body  606  where the tubular elongate body  606  includes at least a first interior passageway  610  which extends longitudinally in the tubular elongate body  606  from a first opening  612  at the proximal end  616  to a second opening  620 , and where the implantable device  602  is shown positioned within a channel  624  of a sheath  626 . In the present embodiment, the adjustable element  604  is shown with a lower profile as compared to the other embodiments of the adjustable elements. In one embodiment, this lower profile is due to the adjustable element  604  being preshaped. In one embodiment, when the adjustable element  604  has no fluid volume inside its chamber, the walls of the adjustable element  604  can be folded around the tubular elongate body to provide for the lower profile. One example of folding the adjustable element  604  is shown in  FIG. 6B . Folding the adjustable element  604  around, or onto, the tubular elongate body can also be done with any of the embodiments shown in the Figures. 
     The implantable device assembly  600  further includes a rear port element  630 , which is releasably coupled to the proximal end  616  of the tubular elongate body  606 . In one embodiment, the rear port element  630  includes a rear port wall  632  having an inner surface  634  and an outer surface  638 . In an additional embodiment, the rear port element  630  includes an elastic septum  636 . The inner surface  634  of the rear port wall  632  defines a cavity  634  and a rear port lumen  640 , where the rear port lumen  640  has a lumen outlet  644 . The lumen outlet  644  can then be coupled to the first interior passageway  610  to provide fluid communication between the cavity  634  and the chamber  650  of the adjustable element  604 . 
     In one embodiment, the outer surface  638  of the rear port wall  632  is adapted to be coupled to the inner surface  646  of the tubular elongate body  606 . For example, the outer surface  638  of the rear port element  630  can include one or more barbs  660  which are adapted to engage or seat in the wall  662  of the tubular elongate body  606  when the rear port element  630  is inserted into the first interior passageway  610 . Alternatively, the outer surface  638  of the rear port element  630  can include one or more bumps which encircle the outer surface  638 , where the one or more bumps have a diameter that is generally larger than the remainder of the outer surface  638  of the rear port element  630 . Once engaged, the outer surface  638  and the first interior passageway  610  create a fluid tight seal. In one embodiment, a clamp element is positioned around the tubular elongate body  606  to further secure the rear port element  630  to the tubular elongate body  606 . In one embodiment, the clamp element is a suture which is tied around the outer surface of the tubular elongate body. 
     Alternatively, the outer surface  638  of the rear port element  630  can have a tapered conical shape which increases in diameter from a first point at or near the distal end of the lumen outlet  644  to a second point proximal to the first point along the outer surface  638 . In one embodiment, the diameter of the outer surface  638  at the first point is less than the diameter of the first interior passageway  610  and the diameter of the outer surface  638  at the second point is greater than the diameter of the first interior passageway. The first point of the outer surface  638  is then inserted into the first interior passageway  610  at the first opening  612  and moved longitudinally into the first interior passageway  610  until the outer surface  638  of the rear port element  630  seats against inner surface of the first interior passageway  610 . In one embodiment, the rear port element is advanced into the first interior passageway  610  to create a fluid tight seal between the outer surface  638  of the rear port element  630  and the first interior passageway  610 . 
     Alternatively, the outer surface  638  of the rear port element  630  can have a diameter that is equal to or greater than the inner diameter of the first interior passageway  610 . When the rear port element  630  is inserted into the first interior passageway  610 , the outer surface  638  of the rear port element  630  engages and seats against the inner surface of the first interior passageway  610 . In one embodiment, a suture is tied around the tubular elongate body  606  to further secure the rear port element  630  to the tubular elongate body  606 . Alternatively, the inner surface of the rear port element  630  can have a diameter that is equal to or greater than the outer diameter of the tubular elongate body  606 . The inner surface of the rear port element  630  is then positioned around the outer surface of the tubular elongate body  606  to form a fluid tight seal. 
     In one embodiment, the tubular elongate body is constructed of at least one polymer, where the polymer can include thermoplastics and/or thermoset polymers. Examples of polymers suitable for constructing the tubular elongate body include silicone, silicone elastomers, polyurethane, polyethylene, PEEK and/or PET. In one embodiment, the tubular elongate body is created from an extruded length of polymer having any number of cross-section shown in the present Figures. Alternatively, the tubular elongate body is formed by casting a polymer in a mold which defines the surfaces, or boundaries, of the tubular elongate body. 
     Additionally, the tubular elongate body has a length between the proximal end and the distal end in a range of between two (2) centimeters to fifty (50) centimeters, where, in one embodiment, the length is determined by the size of the person and the position within the body that the implantable device is situated. In one embodiment, the length of the tubular elongate body can be adjusted to an appropriate length once the implantable device has been positioned within the body. The rear port element is then coupled to the elongate body and positioned subcutaneously. 
     One reason for having a releasably attachable rear port is to reduce the overall size (e.g., diameter) of the sheath used to introduce the implantable device. Typically, the rear port element has a size (e.g., one or more dimensions, such as an outer diameter) that is larger than the inner diameter of the sheath. Besides other potential problems, one difficulty is either extending the sheath around the rear port element, or providing a rear port element that can be compressed to a size which allows the implantable device to be moved through the sheath. In one embodiment, this problem is solved by utilizing the implantable device shown in any one of  FIG. 1 ,  FIG. 2 ,  FIG. 3 ,  FIG. 4  and  FIG. 6 , where the implantable device, absent the rear port element, is first slid through the sheath ( FIGS. 1 ,  2 ,  3  and  6 ), or delivered through the use of the sleeve  424  ( FIG. 4 ), the sheath removed from around the implantable device and the rear port element coupled to the tubular elongate body as will be more fully described below. 
     In an alternative embodiment, an implantable device is provided where the device includes a rear port element, a tubular elongate body and an adjustable element. The distal end of the implantable device is then positioned within the channel of the sheath and is moved longitudinally within the sheath either through the use of a push rod introduced into a second interior lumen, through force applied to the distal end of the tubular elongate body or through a sleeve moving within the sheath. In one embodiment, once the implantable device has moved through the sheath to the point where the adjustable element is positioned within the body, the adjustable element is inflated, the sleeve (if present) is removed, and the sheath is then withdrawn from the body. In the embodiments where a rear port element is present, however, the sheath must be passed around the rear port element in order to remove the sheath from the body. 
     Referring now to  FIG. 7A , there is shown one embodiment of an implantable device assembly  700 . The implantable device assembly  700  includes an implantable device  704  and a sheath  708 . The implantable device  704  is shown with a rear port element  712  positioned adjacent a channel opening  716  of the sheath  708 . The sheath  708  further includes a wall  720 , where the wall  720  has at least a first portion  724  and a second portion  728 . In  FIG. 7A , the second portion is shown as a first area of the wall that extends longitudinally along the body of the sheath  708 , and a second area composes the remainder of the wall. In one embodiment, the second portion  728  of the wall is of a lesser strength as compared to the first portion  724  of the wall. This allows the sheath  708  to be separated along the second portion  728 . In one embodiment, the sheath  708  is separated along the second portion  728  by force applied to the sheath  708  on either side of the second portion  728 . 
     Referring now to  FIG. 7B  there is shown an embodiment of the implantable device assembly  700  where the sheath  708  is being separated along the second portion  728 . As  FIG. 7B  shows, as the sheath  708  is separated along the second portion  728  the sheath  708  is opened into a more planar configuration. This planar configuration allows the sheath  708  to be passed around the rear port element  712 . Thus, the dimension of the rear port element no longer effects whether the implantable device  704  can be removed from the sheath  708 . 
     The sheath  708  shown in  FIG. 7A  and  FIG. 7B  is shown having one second portion  728 . A sheath having additional second portions is also possible. For example, the sheath  708  in  FIG. 7C  is shown having two second portions  728 , where the each of the two second portions  728  are positioned on opposite sides of the sheath  708 . 
     Referring now to  FIG. 8A  there is shown one embodiment of a sheath  800  according to the present subject matter. The sheath  800  includes a wall  806  having an inner surface  812  and an outer surface  816 . In one embodiment, the inner surface  812  defines a channel  820  which passes through the sheath  800  from a first sheath opening  824  to a second sheath opening  828  (shown with hidden lines). The channel  820  of the sheath  800  has a size which is appropriate to receive at least a portion of an implantable device, and through which at least a portion of the implantable device can pass. 
     Sheath  800  also includes scorings, or a line of weakness, which extend longitudinally along the wall  806  from a proximal end  834  to a distal end  836 . In one embodiment, a first scoring  832  is provided which extends longitudinally along the wall  806 . In one embodiment, the first scoring  832  provides the second portion of the wall that is of the lesser strength as compared to the first portion. In the present embodiment, the second portion of the wall  806  is of lesser strength due to the absence of, or the thinning, of the material comprising the wall  806 . In an alternative embodiment, the line of weakness is created by a plurality of closely spaced perforations, where the perforations extend through the wall  806 . In one embodiment, the closely spaced perforations extend longitudinally along the sheath to create the line of weakness. 
     In one embodiment, scoring of the wall  806  can be accomplished during the process of creating the sheath. For example, the sheath can be created by extruding a polymer (or one or more polymers, including co-polymers) through a die which includes one or more protrusions for creating the scoring. Alternatively, the scoring could be accomplished after the sheath has been either extruded or cast, where the scorings are added by either removing or deforming the sheath material to create the region of lesser strength as compared to the remainder of the wall. Because of the lesser strength along the first portion, the sheath  800  can be split along the first scoring  832  when sufficient force is applied to the region of the first scoring  832  to cause the wall to separate. In addition, a stress concentration point in the form of a notch or nick at a proximal edge of the scoring can be used to ensure the sheath splits along the line, or path, of weakness. 
     Referring now to  FIG. 8B , there is shown an additional embodiment of the sheath  800  according to the present subject matter. The embodiment of the sheath  800  in  FIG. 8B  is shown where the wall  806  includes two scorings extending longitudinally along the wall  806  from a proximal end  834  to a distal end  836  to allow for the sheath  800  to be separated into two pieces. In  FIG. 8B , the two scorings include the first scoring  832  and a second scoring  840 . In one embodiment, the first and second scorings  832  and  840  are positioned on opposite sides of the sheath  800 . Alternatively, the first and second scorings  832  and  840  can be located at any position on the wall  806 . 
     Referring now to  FIG. 9 , there is shown an alternative embodiment of a sheath  900  according to the present subject matter. The sheath  900  includes a wall  906  having an inner surface  912  and an outer surface  916 . In one embodiment, the inner surface  912  defines a channel  920  which passes through the sheath  900  from a first sheath opening  924  to a second sheath opening  928  (shown with hidden lines). The channel  920  of the sheath  900  has a size which is appropriate to receive at least a portion of an implantable device, and through which at least a portion of the implantable device can pass. 
     Sheath  900  also includes a first edge  930  and a second edge  932 , where the first edge  930  and the second edge  932  are closely adjacent and define a slit  934  between the edges. The slit  934  passes through the wall  906  and extends longitudinally along the wall  906  from a proximal end  936  to a distal end  938 . In one embodiment, the slit  934  provides the second portion of the wall  906  that is of the lesser strength as compared to the first portion. In the present embodiment, the second portion of the wall  906  is of lesser strength due to the cut made through the wall  906 . In one embodiment, creating the slit in the wall  906  can be accomplished during the process of creating the sheath. For example, the sheath can be created by extruding a polymer (or one or more polymers, including co-polymers) through a mold which has a protrusion for creating the slit. Alternatively, the slit could be accomplished after the sheath has been either extruded or cast, where the slit is added by cutting through the wall  906  along a path the extends longitudinally along the sheath  900 . The presence of the slit  934  allows the sheath to be separated at the slit  934  so that the sheath can be passed around the implantable device (not shown). In one embodiment, the sheath is constructed of a elastic material which is adapted to flex so as to allow the implantable device to pass through the slit in the sheath. 
     Referring now to  FIG. 10 , there is shown an additional embodiment of a sheath  1000  according to the present subject matter. The sheath  1000  includes a wall  1006  having an inner surface  1012  and an outer surface  1016 . In one embodiment, the inner surface  1012  defines a channel  1020  which passes through the sheath  1000  from a first sheath opening  1024  to a second sheath opening  1028  opposite the first sheath opening  1024 . The channel  1020  of the sheath  1000  has a size and a volume which is appropriate to receive at least a portion of an implantable device, and through which at least a portion of the implantable device can pass. 
     Sheath  1000  also includes a first edge  1030  and a second edge  1034  that are spaced to define a slot  1038  in the wall  1006 . In one embodiment, the distance between the first edge  1030  and the second edge  1034  is equal to or greater than the outer diameter of the tubular elongate body. Alternatively, the distance between the first edge  1030  and the second edge  1034  is less than the outer diameter of the tubular elongate body, where the tubular elongate body is constructed of an elastic polymer which deforms to allow the tubular elongate body to pass through the slot  1038 . 
     Alternatively, the slot is sufficiently large to afford the passage of at least one of the rear port, tubular elongate body and/or the adjustable element of an implantable device through the slot  1038 , where any of the portions of the implantable device are deformable to allow them to pass through the slot. In one embodiment, the wall  1006  has sufficient stiffness to maintain its shape when inserted into a body (as will be described below) and when an implantable device is passed into the channel, but yet has sufficient elasticity to allow the wall  1006  to deform as the implantable device is passed through the slot  1038 . 
     Referring now to  FIG. 11 , there is shown an additional embodiment of the sheath  1000  according to the present subject matter. The sheath  1000  further includes a layer  1100  over the outer surface  1016 . In one embodiment, the layer  1100  traverses, or extends over, the slot  1038  to form a continuous channel  1020  through the sheath  1000 . In one embodiment, the layer  1100  is made of a material which has a lesser strength than the wall  1006  of the sheath  1000 . In one embodiment, the layer  1100  is adapted to develop a tear and to rip at least longitudinally along the major axis of the sheath as the implanted device is passed through the slot  1038  during insertion. Alternatively, the layer  1100  includes a slit  1110  which passes through the layer  1100 , where the slit  1110  is adapted to allow the implanted device to pass through the slot and the slit during insertion. 
     In one embodiment, the layer is formed by dipping, or casting the sheath  1000  in a polymer in a softened state (either through heat for a thermoplastic or pre-cross linked state for a thermosetting polymer), where the sheath  1000  is provided with a removable casting core which fills the volume of the channel  1020  and allows the layer to be formed over the slot  1038 . In one embodiment, the layer  1100  is formed from polyurethane, Teflon, nylon, nylon elastomers, Pebax™, Polyethylene, silicone, or other flexible polymers or polymer blends as are known. 
       FIG. 12A  shows one embodiment of an implantable device assembly  1200  according to the present subject matter. The implantable device assembly  1200  includes an implantable device  1204 , having a rear port element  1208 , a tubular elongate body  1212  and an adjustable element  1216 . The implantable device assembly  1200  also includes a sheath  1220 , where in the present embodiment the sheath  1220  includes a slot  1222  as previously described. 
     In one embodiment, as the sheath  1220  is removed from around the implantable device  1204 , the wall  1226  of the sheath is bent or deformed, shown generally at  1230 , to allow the components of the implantable device  1204  to pass through the slot  1222 . As the sheath  1220  is being bent to allow the implantable device  1204  to pass through the slot  1222  the sheath can also be pulled in the general direction of the rear port  1208 , which will be more fully understood later in this document to be important in removing the sheath  1220  from a location in a body where an implantable device is desired. 
       FIG. 12B  shows an additional embodiment of an implantable device assembly  1234  according to the present subject matter. The implantable device assembly  1234  includes an implantable device  1204 , having a rear port element  1208 , a tubular elongate body  1212  and an adjustable element  1216 . The implantable device assembly  1234  also includes a sleeve  1236 , where in the present embodiment the sleeve  1236  includes a slot  1238  and an inner surface  1240 . In one embodiment, the inner surface  1240  defines a receptacle region  1244  which has a shape and a size to receive at least a portion of the rear port element  1208 . 
     In the present embodiment, the implantable device  1204  is shown with the adjustable element  1216  in an expanded state. In one embodiment, the implantable device  1204  is moved at least partially through a sheath (not shown) through force applied at the proximal end  1246  of the sleeve  1236 , which has a stiffness sufficient to allow the force to move the implantable device  1204 . As previously described, the distal end  1248  of the sleeve  1236  abuts the ridge, or ledge, formed at the point where the tubular elongate body  1212  is connected to and sealed to the adjustable element  1216 . Once the implantable device  1204  has been positioned in the body, fluid is injected into the rear port element  1208  to inflate the adjustable element  1216 . Once the adjustable element  1216  is inflated, the sheath is removed (as previously described). The sleeve  1236  is then removed from around the implantable device  1204  by first removing the rear port element  1208  from the receptacle region  1244  and then passing the tubular elongate body  1212  through the slot  1238  of the sleeve  1236 . In the present embodiment, the sleeve  1236  is sufficiently stiff so that the walls of the sleeve  1236  flex very little, if at all, as the tubular elongate body  1212  deforms to pass through the slot  1238 . 
     Referring now to  FIG. 13 , there is shown a schematic view of the implantable device assembly  1300  according to one embodiment of the present subject matter. The implantable device assembly  1300  is shown to include an implantable device  1302  which has an adjustable element  1304  and a tubular elongate body  1306 . In one embodiment, the adjustable element  1304  includes a continuous wall  1308 , including an inner surface  1310  defining a chamber  1316 . The tubular elongate body  1306  includes a peripheral surface  1320 , a proximal end  1326  and a distal end  1328 . In one embodiment, the peripheral surface  1320  is connected to and sealed to the adjustable element  1304  as previously described. 
     The tubular elongate body  1320  also includes at least a first interior passageway  1330  which extends longitudinally in the tubular elongate body  1320  from a first opening  1332  at the proximal end  1326  to a second opening  1334 . In one embodiment, the second opening  1334  is in fluid communication with the chamber  1316  of the implantable device  1302  for adjustably expanding or contracting the adjustable element  1304  by flowable material introduced through the first opening  1332 . Additionally, a detectable marker  1333  is located at or on the distal end of the tubular elongate body  1320  to allow for the position of the implantable device  1300  be located within the tissues of a patient. Alternatively, the detectable marker is imbedded in the continuous wall of the adjustable element  1304 . 
     In one embodiment, the first interior passageway  1330  includes a closed end  1340 , where the closed end  1340  is positioned distal to both the first opening  1332  and second opening  1334 . The closed end  1340  is of sufficient strength and hardness to receive a distal end  1342  of a push rod  1344 , where the closed end  1340  transfers force applied at a proximal end  1346  of the push rod  1344  to the implantable device  1300 . In one embodiment, the first interior passageway  1330  is of sufficient diameter to receive the push rod  1344  which contacts the closed end  1340  to allow force applied to the push rod  1344  to move the implanted device  1302 . 
     The implantable device assembly  1300  further includes a tip  1350 . In one embodiment, the distal end  1328  of the tubular body  1320  forms the tip  1350 . 
     In one embodiment, the tip  1350  is suitable to penetrate the tissue of a patient, where the tip  1350  includes at least a distal end  1354  which is sharped to afford the ability to insert the tip  1350  and the implantable device  1302  into the tissue of a patient. This configuration of the implantable device assembly  1300  allow for the implantable device  1302  to be delivered into the tissue of the patient without the need for a sheath. The tip also has a conical configuration to allow for the tissue being penetrated by the implantable device  1302  to pass over the tip  1350  and the body of the implantable device  1302 . In an additional embodiment, the tip  1350  further includes one or more sharpened edges which extend from the distal end  1354  of the tip  1350  toward a proximal end  1358  of the tip  1350 . In an additional embodiment, the adjustable element  1304  is adapted to expand under pressure from a volume of flowable material introduced through the first opening to at least partially envelop the tip  1350 . 
     The present embodiment shows an example of a “self-dilating” device, where the implantable device is used to create its own pathway into the body of the patient. An advantage of the present embodiment is that the size of the opening created for inserting the implantable device is keep to a minimum, as only a channel the approximate size of the implantable device is created. Also, the surgical procedure is expedited as there are fewer items (e.g., obturator, sheath etc.) to insert prior to the actual delivery of the implantable device. 
     The tip  1350  used on the implantable device  1302  can be constructed of a variety of materials. In one embodiment, the tip  1350  is made of a hard plastic, such as polyurethane or PET. Alternatively, the tip  1350  is constructed of a biodegradable, or bioabsorbable, material, such as polyglycolic acid or polylactic acid, a dissolvable material such as a starch, or a material that is initially hard, but becomes soft after exposure to moisture, such as a hydrogel material. In this embodiment the tip is bonded to the distal end  1328  of the tubular elongate body. In one embodiment, the bonding is accomplished with a medical grade adhesive, such as silicone. Alternatively, the tip  1350  is cast onto the distal end  1328  of the tubular elongate body  1320 , where the distal end  1328  has been configured and shaped to receive the tip material so as to lock the tip  1350  in place. 
     The implantable device assembly  1300  further includes a rear port element  1360 , which is releasably coupled to the proximal end  1326  of the tubular elongate body  1320 . The rear port element  1360  is similar to the rear port element previously described, and is adapted to be coupled to the tubular elongate body  1320  to create a fluid tight seal between the outer surface of the rear port element  1360  and the inner surface of the first interior passageway of the tubular elongate body  1320 . 
     Referring now to  FIG. 14 , there is shown an additional embodiment of an implantable device assembly  1400  according to the present subject matter. The implantable device assembly  1400  is shown to include an implantable device  1402  which has an adjustable element  1404  and a tubular elongate body  1406 . The tubular elongate body  1406  includes a peripheral surface  1420 , a proximal end  1426  and a distal end  1428 . In one embodiment, the peripheral surface  1420  is connected to and sealed to the adjustable element  1404  as previously described. In one embodiment, the adjustable element  1404  includes a continuous wall  1408 , including an inner surface  1410  defining a chamber  1416  and at least one detectable marker  1411  positioned at the distal end  1428  of the tubular elongate body  1406 . Alternatively, the maker  1411  can be embedded in the continuous wall of the adjustable element  1404  to allow for the position of the implantable device  1400  to be located and its shape to be visualized within the tissues of a patient. Detectable markers can also be embedded in the tubular elongate body  1406 . 
     The tubular elongate body  1406  includes a first interior passageway  1430  and a second interior passageway  1432 . In one embodiment, the first interior passageway  1430  extends longitudinally in the tubular elongate body  1406  from a first opening  1434  at the proximal end  1426  to a second opening  1436 . The second opening  1436  is in fluid communication with the chamber  1416  of the implantable device for adjustably expanding or contracting the adjustable element  1404  by flowable material introduced through the first opening  1434 , as previously described. 
     The second interior passageway  1432  extends longitudinally along at least a portion of the tubular elongate body  1406  from an inlet  1444  to an outlet  1446 . In one embodiment, the second interior passageway  1432  is of sufficient diameter to receive a push rod  1450 . The push rod  1450  has a proximal end  1454  and a distal end  1458 , where the distal end  1458  of the push rod  1450  has a tip  1460  which is has a sharp point. In one embodiment, the sharp tip  1460  of the push rod  1450  extends through the outlet  1446  of the second interior passageway  1432  to provide the initial cutting tip of the implantable device apparatus  1400 . In one embodiment, the distal end  1428  of the tubular elongate body  1420  has a conical taper which extends from the tip  1460  to allow the distal end  1428  to create a uniform conical shape suitable for penetrating tissue. 
     In one embodiment, to position the push rod  1450  within the second interior passageway  1432  with only the tip  1460  protruding from the distal end  1428 , there is provided a first shoulder  1470  in the second interior passageway  1432  against which a corresponding second shoulder  1474  on the push rod  1450  seats. In one embodiment, the first shoulder  1470  is formed by a change in diameter of the second interior passageway  1432 , where the inner surface  1478  of the second interior passageway  1432  changes from having a first passageway diameter to a second passageway diameter, where the second diameter is smaller than the first diameter. The second shoulder  1474  is also formed by a change in diameter of the push rod  1450 , where the exterior surface of the push rod  1450  changes from having a first rod diameter to a second rod diameter. Once the push rod  1450  is inserted into the second channel it is advanced so that the second shoulder  1474  abuts the first shoulder  1470  and so that the tip  1460  protrudes from the distal end  1428 . Force applied to the push rod  1450  can then be transferred to the implanted device  1402  so that it may be advanced into the tissue of a patient. 
     The implantable device assembly  1400  further includes a rear port element  1480 , which is coupled to the proximal end  1426  of the tubular elongate body  1420 . In one embodiment, the rear port element  1480  is similar to the rear port element previously described, and is adapted to be releasably coupled to the tubular elongate body  1420  to create a fluid tight seal between the outer surface of the rear port element  1480  and the inner surface of the first interior passageway of the tubular elongate body  1420 . 
     Referring now to  FIG. 15  there is shown a schematic cross-sectional view of an implantable device assembly  1500  according to one embodiment of the present subject matter. As previously described, the implantable device assembly  1500  includes an implantable device  1502  having an adjustable element  1504  and a tubular elongate body  1506 , where the tubular elongate body  1506  includes at least a first interior passageway  1510  which extends longitudinally in the tubular elongate body  1506  from a first opening  1512  at the proximal end  1516  to a second opening  1520 . The implantable device assembly  1500  also includes a tip  1524 , where the tip  1524  has a end suitable for insertion of a tip and device into tissue of the patient as previously discussed. 
     The implantable device assembly  1500  further includes a rear port element  1530 , where the rear port element  1530  is coupled to the proximal end  1516  of the tubular elongate body  1506 . The rear port element  1530  includes a cavity  1532  in fluid communication with the first opening  1512  of the first interior passageway  1510 . In one embodiment, the rear port element  1530  also includes an elastic septum  1540  through which the cavity  1532  is accessed. In one embodiment, the elastic septum  1540  has a structure, a size and function as previously described. As shown in  FIG. 15 , the elastic septum  1540  has a bulbous configuration. 
     In the present embodiment, the tubular elongate body  1506  has a stiffness sufficient to allow force applied at the proximal end of the tubular elongate body  1506  to move the implantable device  1502  through soft tissue of a patient. In one embodiment, the stiffness of the tubular elongate body is determined based on the type of material used in constructing the tubular elongate body. Alternatively, support elements can be added to the tubular elongate body. For example, a metal coil  1550  is placed longitudinally within the tubular elongate body to increase the stiffness of the tubular elongate body  1506 . In one embodiment, the metal coil  1550  allows force applied along the longitudinal axis of the implantable device  1502  to be transferred to the tip  1524 . 
       FIG. 15  also shows one embodiment of the adjustable element  1504  in an inflated state. In the present embodiment, the adjustable element  1504  is adapted to partially envelop the tip  1524 . One reason for enveloping the tip with the adjustable element  1504  is to protect the tissue in the implant area from the tip  1524 . The example in  FIG. 15  is just one example of a tip being enveloped by the adjustable element, and other configurations of enveloping the tip can be imagined, such as the tip being completely surrounded by the adjustable element. 
     Referring now to  FIG. 16A , there is shown an additional embodiment of a implantable medical device assembly  1600  according to the present invention. The implantable medical device assembly  1600  includes a sheath  1604  having a wall  1606  having an inner surface  1612  and an outer surface  1616 . In one embodiment, the inner surface  1612  defines a channel  1620  which passes through the sheath  1604  from a first sheath opening  1624  to a second sheath opening  1628  opposite the first sheath opening  1624 . The channel  1620  of the sheath  1604  has a size and a volume which is appropriate to receive at least a portion of an implantable device, and through which at least a portion of the implantable device can pass. Sheath  1604  also includes a first edge  1630  and a second edge  1634  that are spaced to define a slot  1638  in the wall  1606 . In one embodiment, the distance between the first edge  1630  and the second edge  1634  is equal to or greater than the outer diameter of the tubular elongate body. 
     The implantable medical device assembly  1600  further includes an implantable medical device  1640 . As previously described, the implantable device  1640  includes an adjustable element  1644  and a tubular elongate body  1648 , where the tubular elongate body  1648  includes at least a first interior passageway which extends longitudinally in the tubular elongate body  1648  from a first opening at the proximal end  1650  to a second opening, and where the implantable device  1640  is shown positioned within the channel  1620  of the sheath  1604 . 
     The implantable device assembly  1640  further includes a rear port element  1654 , as previously described, where the rear port element  1654  is coupled to the proximal end  1650  of the tubular elongate body  1648 . In one embodiment, the rear port element  1654  is coupled to the proximal end  1650  of the elongate body  1648  using chemical adhesives, or alternatively, using sonic welding techniques as are known in the art. In an additional embodiment, the rear port element  1654  and proximal end  1650  are formed together in a polymer molding process, such as liquid injection molding, as are known in the art. 
     In the present embodiment, the adjustable element  1644  is shown folded into the channel  1620  of the sheath  1604 . In one embodiment, the folding of the adjustable element  1644  is shown in  FIG. 16B , where the adjustable element  1644  is shown where the walls of the adjustable element  1644  are folded in on themselves so that there are three or more portions of the wall adjacent to each other. Folding the walls of the adjustable element  1644  allows for the size of the adjustable element  1644  to be reduced. This in turn can allow for the size of the sheath  1640  to be reduced. In an additional embodiment, the folding the of the adjustable element can also assist in deploying the implantable device  1640  from the sheath  1604 . In one embodiment, as the adjustable element  1644  is inflated a first portion  1670  (shown encircled in a broken line) of the adjustable element  1644  emerges through the slot  1638  ( FIG. 16C ). As the adjustable element  1644  continues to inflate, the first portion  1670  grows in size to become larger than the slot  1638 . As further fluid is passed into the adjustable element  1644 , the walls of the adjustable element  1644  begin to force the adjustable element  1644  completely through the slot  1638  ( FIG. 16D ). Once the adjustable element  1644  has passed through the slot  1638  the sheath  1604  can then be removed. 
     Referring now to  FIG. 17 , there is shown one embodiment of a method for adjustably restricting a body lumen according to the present subject matter. The implantable device assembly previously discussed is adapted to be surgically implanted into body tissue of a patient adjacent to a body lumen for coaptating the body lumen. At  1700 , a sheath in introduced into body tissue of a patient. In one embodiment, the sheath is as previously described, where the sheath is introduced by first placing an obturator, or a dilator, having an end suitable for penetrating tissue through the channel of the sheath. Once the body lumen, such as the urethra, is located a small incision is made in the skin and the obturator is used to introduce the sheath into the body tissue to a desired location adjacent the urethra. This procedure is usually carried out under a local anesthetic with visual guidance, for instance under fluoroscopy by a physician. The obturator is of sufficient strength and rigidity to allow the insertion of the sheath into the tissue of the patient adjacent and parallel with the urethra. 
     In one embodiment, the sheath is inserted near the meatus urinarius and advanced through the periurethral tissue adjacent the urethra. In one embodiment, a detent or mark is provided on the sheath to ensure that the sheath is appropriately placed at the correct depth in the patient&#39;s body tissue. In an additional embodiment, the elongate body of the implantable medical device is available having a variety of lengths to accommodate the patient&#39;s anatomic structure so as to facilitate placement of the rear port element near the patient&#39;s skin In one embodiment, the tubular elongate body of the implantable device once inserted into the patient&#39;s tissue can be cut to length prior to attaching the rear port element. 
     As previously described, the sheath includes a channel having a longitudinal axis and one or more dimensions perpendicular to the longitudinal axis. An example of the one or more dimensions includes a diameter of the channel, where the channel has a circular cross-section. Alternatively, the channel may have an elliptical cross-section, where the dimensions then have a major and a minor axis which define the ellipse. 
     At  1710 , an implantable device is inserted at least partially through the channel of the sheath. In one embodiment, the implantable device includes an adjustable element, a tubular elongate body and a rear port element, as were previously described. In the present embodiment, the rear port element further includes at least one dimension that is larger than the one or more dimensions of the sheath. Examples of these were noted in the figures and the discussion for  FIGS. 5 to 12  of the present subject matter. By way of example, at least one dimension that is larger than the one or more dimensions of the sheath can include the diameter of the outer surface of the rear port element and the inner diameter of the sheath. In this situation, the implantable device would not pass through the channel of the sheath as the diameter of the rear port element is larger than the diameter of the sheath. 
     The implantable medical device is advanced or moved at least partially though the channel to position the adjustable element distal to the sheath and adjacent the body lumen to be restricted. In one embodiment, the adjustable element is positioned adjacent an urethra. In an additional embodiment, two or more of the implantable medical devices can be implanted within the body tissue adjacent an urethra. The adjustable element is then expanded, or inflated, so as to retain the implantable medical device prior to removing the sheath. 
     At  1720 , the sheath is then passed around the rear port element as the sheath is removed from the body tissue. In one embodiment, this is accomplished by splitting the sheath into one or more pieces as previously described. One manner of providing a sheath that will spilt is to create one or more scores on the sheath as previously described. The scores in the wall of the sheath provide lines of weakness, where the sheath can be torn along these one or more scores to allow the sheath to be passed around the rear port element as the sheath is removed from the body tissue. 
     In an additional embodiment, the sheath can have a slit as previously described, where the sheath is made of a material having the flexibility to allow the sheath to pass around the rear port element by passing the elongate body of the implantable device through the slit as the sheath is removed from the body tissue. Alternatively, the sheath can have a slot as previously described, where the sleeve is made of a material having a stiffness that requires the tubular elongate body of the implantable device to deform as it passes through the slot as the sheath is removed from the body tissue. The rear port element is then position subcutaneously. 
     After the implantable medical device has been implanted so the adjustable element (in its contracted state) is in the desired position adjacent to the urethra, the urethra is restricted to a desired degree by piercing the elastic septum of the rear port with a needle of a syringe and injecting a flowable material through the first interior passageway into the adjustable element. The physician may determine the desired degree of restriction of the urethra by means such as infusing fluid through the urethra past the restriction and measuring the back pressure or visually assessing the amount of coaptation of the urethra lumen after inflation of the adjustable element by use of cystoscopy. The flowable material may be, for example, a saline solution, a flowable gel, or a slurry of particles in a liquid carrier. It may be advantageous to make the flowable material radiopaque so that the degree of membrane inflation may be viewed by x-ray. 
     Referring now to  FIG. 18 , there is shown an additional embodiment of a method for adjustably restricting a body lumen according to the present subject matter. The implantable device assembly previously discussed is adapted to be surgically implanted into body tissue of a patient adjacent to a body lumen for coaptating the body lumen. At  1800 , a sheath is introduced into body tissue of a patient, for example as previously described. In one embodiment, the sheath includes a first portion and a second portion, where at least the first portion of the sheath is introduced into the body tissue. In one embodiment, the sheath is introduced into the body tissue with a dilator, or obturator, which is inserted through the channel of the sheath. 
     Referring now to  FIG. 19 , there is shown one embodiment of a sheath  1900 , where the sheath  1900  includes a wall  1902  defining a channel  1904  having a longitudinal axis. The sheath  1900  further includes a first portion  1906 , a second portion  1908 , and a slot  1912  which extends longitudinally along a wall. In one embodiment, the first portion  1906  and the second portion  1908  include the portion of the sheath  1900  that includes the slot  1912 . In an additional embodiment, a dilator  1916  is shown positioned in the channel  1904  of the sheath  1900 . In one embodiment, the dilator  1916  includes a tip  1920  which is suitable for insertion into body tissue. The tip  1920  of the dilator  1916  is inserted into the channel  1904  at the proximal end  1922  of the channel  1904  and is slid, or moved, through the channel  1904  so that the tip  1920  extends from the distal end  1924  of the sheath  1900 . The sheath  1900  and dilator  1916  are then inserted into the body tissue. 
     Referring again to  FIG. 18 , the sheath is positioned with the first portion of the sheath in body tissue and a second portion of the sheath outside the body tissue at  1810 . In one embodiment, the second portion of the sheath includes at least a portion of the slot. At  1820 , at least a portion of the implantable device is then moved through the channel of the sheath into the first portion of the sheath located in the body tissue. In one embodiment, at least a portion of the implanted device is positioned, or passed, through the slot at the second position. 
     Referring now to  FIG. 20 , there is shown one embodiment of a sheath  1900  positioned within body tissue  2000 . In one embodiment, the sheath is inserted near the meatus urinarius and advanced through the periurethral tissue adjacent the urethra  2010 . In one embodiment, a detent or mark is provided on the sheath to ensure that the sheath is appropriately placed at the correct depth in the patient&#39;s body tissue. In one embodiment, the sheath  1900  is inserted into the body tissue so that the first portion  1906  is located within the body tissue and the second portion  1908  is not located within the body tissue. An implantable medical device  2020  is then positioned within the channel through the slot  1912 . 
     The implantable medical device  2020  is then advanced, or moved, through the channel  1912  of the sheath  1900 . In one embodiment, the implantable device is moved through the channel  1912  by inserting a rod having a distal end into the channel  1904  of the sheath  1900  until the distal end contacts implantable device  2020 . Force is then applied to the distal end of the rod to move the implanted device  2020  at least partially through the channel  1912  of the sheath. Alternatively, the dilator could be used to move the implantable device through the channel  1912 . 
     In an alternative embodiment, in order to move the implantable device  2020  the device is pushed towards the distal end of the sheath. In one embodiment, the implantable device  2020  includes an interior passage way, such as a second interior passageway previously described, where the interior passage way includes a first opening into which a push rod can be inserted until it contacts a closed end of the interior passage way which is distal to the first opening. Force can then be applied to the push rod to move the implanted device at least partially through the channel of the sheath. Alternatively, moving at least a portion of an implantable device includes positioning a sleeve, as previously described around at least a portion of the implantable device. In one embodiment, the sleeve is positioned around the tubular elongate body as previously described. Force is then applied to the sleeve to move the implanted device at least partially through the channel of the sheath. Alternatively, the tubular elongate body  2025  includes a support member, such as a coil located within the tubular elongate body as previously described, and pushing the implantable device includes applying force through the support member to move the implanted device at least partially through the channel of the sheath to position the adjustable element beyond the distal end of the sheath. In one embodiment, the adjustable element  2030  of the implantable device  2020  is moved through the channel to position the adjustable element  2030  beyond the distal end of the sheath  1900 . Flowable material can then be introduced into the adjustable element to restrict a body lumen as previously discussed. 
     One feature of this invention relates to the adjustability of the adjustable element postoperatively. This adjustability is effected because the elastic septum is located remote from the adjustable element but near and under the patient&#39;s skin The rear port element and the elastic septum are located by, for instance, manual palpation of the skin region and the needle of the syringe is inserted through the skin and septum so as to add or remove material from the adjustable element, thus increasing or decreasing the restriction of the body lumen. 
     In an additional embodiment, the rear port element can have any number of shapes that is more easily identifiable in the tissue during palpation by a physician. For example, the rear port element can have a oval cross-sectional shape. Alternatively, the rear port element can have a square cross-sectional shape. Other cross-sectional shapes can be imagined which would assist a physician in locating the rear port element. Additionally, the elastic septum of the rear port element can be positioned at a level that is higher (e.g., domed or bulbous), or lower, than that rear port element wall surrounding the elastic septum. This configuration assists the physician in finding the elastic septum quickly as it is set apart from the remainder of the rear port element. The rear port element can then be utilized for preforming post-operative adjustments (e.g., days, weeks, months, years) of the size of the adjustable element.