Abstract:
A device and method of using the device for contraception or sterilization and particularly for reversible contraception by occluding a reproductive lumen to prevent the passage of reproductive cells through the lumen for a desired period of time until the patient wishes to become fertile again and then be reopened. The occluding member preferably comprises a tubular framework formed from a shape memory material configured to be implanted in a reproductive lumen. The occluding member is implanted within a body lumen, secured to the wall of the reproductive lumen and then collapsed to collapse the wall and occlude the lumen. Alternatively, the occluding member may be collapsed upon a solid plug. The closure of the reproductive lumen may be reversed by introducing a balloon catheter and by a series of inflations of the balloon reexpanding the collapsed occluding member or by removing the plug. The occluding member and the plug may be configured to facilitate endothelialization, to provoke an inflammatory responses or to deliver a drug.

Description:
FIELD OF INVENTION 
     This invention relates to the field of contraceptive and sterilization devices and more particularly to reversible contraceptive devices and the methods of using such devices. 
     BACKGROUND OF THE INVENTION 
     Conventional contraceptive strategies generally fall within three categories: physical barriers, drugs and surgery. While each have certain advantages, they also suffer from various drawbacks. Barriers such as condoms and diaphragms are subject to failure due to breakage and displacement. Drug strategies, such as the pill and Norplant™, which rely on artificially controlling hormone levels, suffer from known and unknown side-effects from prolonged use. Finally, surgical procedures, such as tubal ligation and vasectomy, involve the costs and attendant risks of surgery, and are frequently not reversible. Thus, there remains a need for a safe, effective method of contraception, particularly a non-surgical method which is reversible. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a contraceptive or sterilization system for occluding a reproductive tract or lumen to prevent the passage of reproductive cells through the tract or lumen. The invention includes an occluding member expandable within the body lumen from a first configuration suitable for introduction into the body lumen to a second larger configuration to facilitate securing the expanded occluding member to at least a portion of a wall which defines the reproductive body lumen. The invention also includes means to facilitate securing the expanded occluding member to the wall of the body lumen and means to contract the expanded occluding member and the wall portion secured to the occluding member to occlude the reproductive body lumen sufficiently to prevent the passage of reproductive cells therethrough. 
     One presently preferred embodiment of the invention comprises a reversible contraceptive system which can be used to occlude either the fallopian tubes of a female patient, the vas deferens of a male patient or other reproductive tract. A key feature of the contraceptive system is a occluding member which is first secured to the wall defining the reproductive tract in an expanded condition and then is collapsed to smaller transverse cross-sectional dimensions to cause the collapse of the secured portion of the wall and thereby block the vessel passageway to prevent the passage of reproductive cells. The occluding member may be reopened by any number of suitable means. For example, by collapsing the occluding member about a plug or mandrel which can be left in place to effectively blocking the passageway until the patient wishes to reverse the procedure. The plug can be removed by suitable means such as conventional laparoscopic or other instruments to reopen the passageway. A balloon dilatation catheter may be used to further expand the opening once the plug is removed Other ways of reopening the reproductive lumen include leaving the proximal portion of the occluding member open when the member is collapsed so that an expandable member such a balloon on a catheter can be inserted and expanded. By means of a series of expansions and stepped advancements, the entire passageway can be reopened. 
     Preferably, the occluding member comprises a tubular member formed from a shape-memory alloy material and has a primary configuration which is relatively small in transverse dimensions to facilitate the insertion of the member into the desired body lumen. Once in place, the occluding member is then expanded to a second configuration with transverse dimensions roughly corresponding to or slightly larger than the body lumen so that the occluding member can be secured to the wall defining the body lumen. With the open, lattice-like framework of the occluding member expanded within the body lumen, endotherlialization through the open structure secures the occluding member to the wall defining the body lumen. By heating the occluding member formed of shape-memory alloy material to a temperature at or above the transition temperature of the shape-memory material, it transforms to a remembered closed or collapsed configuration which causes the wall secured to the occluding member to close down so that the passageway therethrough is occluded. The occluding member may be delivered to the desired location within the body lumen by suitable means such as a conventional balloon catheter similar to those used for delivering stents, aortic grafts and various types of prosthesis. 
     In one presently preferred embodiment, the occluding member has an open or lattice-like framework so that the growth of endothelial tissue through the openings of lattice-like framework so as to interconnect the occluding member and the wall of the body lumen. The surface of the occluding member may be treated to promote the endothelialization. 
     Once the occluding member is implanted into the body lumen and it has been sufficiently endothelialized to secure it to the body wall (which may take a week or more), it may be activated by warming the occluding member to a temperature at or above the transition temperature of the shape-memory material so it may revert to its remember constricted shape. Since the endotheliaization has secured the occluding member to the wall of the body lumen, the contraction of the occluding member to its remembered collapsed shape, causes the wall defining the body lumen to collapse along with the occluding member, effectively blocking the passageway. Alternatively, a plug may be located within the interior of the occluding member prior to heat activation so that the occluding member collapses onto the plug to block the lumen. 
     The occluding member may be mounted onto the exterior of a balloon of a dilatation balloon catheter in the first configuration with small transverse dimensions, and then be introduced and positioned within the region of the reproductive lumen to be occluded. The balloon is inflated to expand the occluding member, preferably with the outer diameter slightly larger than the inner dimensions of the reproductive lumen to which it is secured. The occluding member will remain in the open configuration until heated to a temperature at or above its martensite to austenite transition temperature which causes it to revert to its collapsed state. If the occluding member is collapsed about a plug, the plug may be extracted to reopen the passageway when the patient wishes to become fertile again. 
     The present invention provides effective sterilization or contraception for both males and females and importantly it is easily reversed. Moreover, the implantation and activation of the occluding member as well as the subsequent restoration of vessel patency requires easily used minimally invasive devices such as catheters, guidewires, guiding catheters and the like. These and other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying exemplary drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a catheter with an occluding member embodying features of the invention mounted on an expandable member on a distal section of the catheter. 
         FIGS. 2 and 3  show one embodiment of the occluding member in expanded and contracted or closed configurations respectively. 
         FIGS. 4 and 5  show another embodiment of the occluding member in expanded and closed configurations respectively. 
         FIGS. 6 and 7  show yet another embodiment of an occluding member in expanded and closed configurations respectively. 
         FIG. 8  depicts the occluding member on a delivery catheter as shown in  FIG. 1  within a reproductive tract or lumen. 
         FIG. 9  illustrates the expansion of the occluding member within the reproductive tract or lumen. 
         FIG. 10  illustrates the female reproductive anatomy and shows the occluding member positioned within one of the patient&#39;s fallopian tubes. 
         FIG. 11  illustrates the male reproductive anatomy and depicts an expanded occluding member within a vas deferens of a male patient. 
         FIG. 12  illustrates the occluding member secured to the wall of the reproductive tract by epithelial tissue. 
         FIG. 13  is a transverse cross-sectional view of the expanded epithelized occluding member as shown in  FIG. 12  taken along the lines  13 — 13 . 
         FIG. 14  shows the occluding member in a collapsed state after being activated by warmed saline. 
         FIG. 15  is a transverse cross-sectional view of the collapsed occluding member as shown in  FIG. 14  taken along the lines  15 — 15 . 
         FIG. 16  is similar to  FIG. 14  and illustrates the occluding member collapsed about an elongated removable plug or mandrel. 
         FIG. 17  illustrates a transverse cross section of the occluding member shown in  FIG. 16 , taken along line  17 — 17 . 
         FIG. 18  shows the occluding member being activated in a location distal to the proximal extremity thereof in order to keep the proximal end partially open to facilitate reopening the passageway. 
         FIG. 19  shows an embodiment of the occluding member having hooks. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a catheter  10  useful in the practice of the invention, which comprises an elongated shaft  12  having an inflation lumen  14  which is in fluid communication with inflatable member  16  mounted on a distal section of the catheter shaft and adapter  18 . Occluding member  20 , a self-supporting metallic member of shape-memory material, closely conforms to the diameter of the uninflated inflatable member  16  to facilitate introduction into the desired body lumen. Occluding member  20  is formed so that it has a remembered collapsed configuration with relatively small transverse dimensions. The occluding member  20  may be deformed to facilitate mounting onto the inflatable member  16  and is expanded by the inflatable member to an open expanded configuration within a body lumen. Upon heating to a transition temperature it will revert to the remembered configuration. In this embodiment the occluding member  20  has an open, lattice-type structure facilitating endothelialization which secures the occluding member to the wall defining the body lumen. Preferably, occluding member  20  can be deformed to an expanded diameter, preferably equal to or slightly larger than the dimensions of the body lumen within which the occluding member is to be disposed. For disposition within a female patient&#39;s fallopian tubes the expanded transverse dimensions should be about 0.1 mm to about 5 mm. 
     The occluding member may have a number of suitable configurations as shown in schematically in  FIGS. 2–7 .  FIG. 2  illustrates occluding member  22  in an open configuration and  FIG. 3  its relatively small dimensioned configuration for introduction and advancement into the patient&#39;s body lumen. Occluding member  22  may be constructed from a length of shape memory hypodermic tubing. Slots  24  cut into the wall of the tubing allow expansion of the occluding member into an open configuration as shown in  FIG. 2 . Likewise, in  FIGS. 4 and 5 , occluding member  26  is a coil  28  of shape-memory wire or ribbon.  FIGS. 6 and 7  show occluding member  30 , which comprises a braided tube of shape-memory wire or ribbon  32 . Finally, in  FIGS. 1 and 8  occluding member  20  comprises a number of closed sinusoidal rings of shape-memory wire or ribbon and is mounted onto an inflatable member  16  of catheter  10 . 
     Inflation of inflatable member  16  expands occluding member  20  in a reproductive tract  38  to an open, relatively large diameter configuration as shown in  FIG. 9 . 
     In each of these embodiments, the shape memory material of the occluding member should have a transition temperature sufficiently above the normal variation of human body temperature to prevent accidental activation which might prematurely collapse the occluding member. On the other hand, the transition temperature should be high enough so that thermal activation of the occluding member does not cause undesirable thermal damage to the surrounding tissue. The shape memory-material is preferably a shape memory, nickel-titanium alloy such as NITINOL and preferably has a transition temperature of between about 43° C. to about 70° C. 
     In each of the embodiments described above, certain conventional refinements may be employed. For example, the surface of the occluding member&#39;s framework may be designed to facilitate endothelial growth. Such modifications generally comprise providing the occluding member with an open or lattice-like framework to promote endothelial growth into as well as around the member to ensure it secure attachment to the wall of the body lumen. Suitable surface techniques include EDM machining, laser drilling, photo etching, scintering and the like. Additionally, increasing the surface area of the occluding member can also provide greater adhesion for the endothelial tissue. Suitable surface treatments include plasma etching, sand blasting, machining and other treatments to roughen the surface. In other embodiments, the shape-memory material may be coated or seeded to spur endothelialization. For example, the occluding device can be coated with a polymer having impregnated therein a drug, enzyme or protein for inducing or promoting endothelial tissue growth. In yet another refinement, the occluding member could be plated with or otherwise incorporate copper to produce an inflammatory response in the tissue of the wall defining the body lumen, which further contributes to the obstruction of the lumen. Other inflammatory materials my be suitable as well. For example, the occluding member could be radioactive, emitting alpha, beta or gamma particles. 
     The practice of the invention comprises the following general steps. An occluding member  20  having relatively small transverse dimension is mounted onto the exterior of balloon  16  of catheter  10  as shown in  FIG. 1 . The catheter  10  is advanced under fluoroscopic or endoscopic visualization until occluding member  20  is positioned within one of the female patient&#39;s fallopian tubes  34 , as shown in  FIG. 10 . Inflation fluid is introduced through adapter  18  to inflate inflatable member  16 . As shown in  FIGS. 9–10 , inflation of inflatable member  16  expands occluding member  20  to an open configuration and lodging it in body lumen  38 . Catheter  10  is removed, leaving the expanded occluding member  20  implanted in body lumen  38  as shown in  FIG. 12 . Another expandable member is delivered to the patient&#39;s other fallopian tube and expanded therein in the same manner. Alternatively, the occluding member may be expanded into positioned within the vas deferens  36  of a male patient as shown in  FIG. 11  to provide male contraception using the same procedures. 
     Over a period of a week or more epithelial cells lining the lumen will proliferate, growing around the open framework of occluding member  20  as shown in  FIGS. 12 and 13  thereby securing the wall defining the body lumen  38  to the expanded occluding member  20 . After the expanded occluding member  20  is sufficiently epithelized within the patient&#39;s reproductive tract  38 , it is thermally activated to return it to its remembered collapsed configuration. The occluding member may be activated by several means, including warmed fluid, RF energy, laser energy, or other suitable energy sources. A suitable activation system is shown in  FIG. 14  where the distal end of catheter  40  is positioned adjacent to the occluding member  20 , saline fluid somewhat above the transition temperature is introduced to bathe occluding member  20 , raising its temperature to the transition point or higher, causing occluding member  20  to collapse to its closed, reduced-diameter configuration. The layer of epithelial tissue that forms within the lattice-like structure of the occluding member helps block and seal the lumen so as to prevent the passage of reproductive cells, eggs or sperm cells. 
     In an alternative embodiment of the invention is shown in  FIG. 16  where a plug  42  is positioned inside occluding member  20  in the expanded condition so that upon activation the occluding member  20  collapses onto plug  42 , blocking the lumen  38 . The plug is preferably formed from an inert material such as a fluoropolymer, e.g. PTFE. Other suitable materials include high density polyethylene and silicone rubber. A number of modifications to the plug may also be suitable. For example, the plug could be used as a drug delivery device, similar to the Norplant™ device. The plug could also be used to provoke an inflammatory response as described above to augment the occlusion of the lumen. In such embodiments, plug  42  preferably has an outer diameter from about 0.25 mm to about 4 mm. The plug  42  may also have holes, deep grooves or which help to preserve at least part of the natural lining of the reproductive tract. 
     The occlusion of the lumen may be reversed simply by removing the plug  42 . If a passageway larger than passageway left by the removed plug  42  is desired, a balloon catheter can be advanced within the body lumen until the balloon is within the lumen left by the removal of the plug and then the balloon on the catheter is inflated to expanded the occluding member  20 , deforming it into an open configuration. It may be desirable when activating the expanded occluding member to the collapsed configuration to leave the proximal end of the occluding member somewhat open or in an expanded condition to facilitate the introduction of dilatation balloon on a catheter to facilitate the opening of the body lumen. As shown in  FIG. 15 , the catheter  40  used to activate the occluding member may be positioned within the proximal end of the occluding member, so that the proximal end is unable to completely revert to its closed configuration. The reproductive tract could be subsequently close should contraception again be desired by heating the occluding member  20  so as to activate the transformation thereof to the collapsed configuration. 
     In embodiments of the invention employing the plug  40 , various other strategies are suitable to reverse the occlusion. For example, the plug  40  can simply be removed, restoring the lumen  38  to patency. Alternatively, the plug  40  may be hollow with a removable core (not shown). This core may be formed from a softer material, such as silicone, or could be threaded, in order to facilitate its removal. Similarly, the plug itself may be threaded so that removal would comprise a twisting motion, minimizing the stress on the tissue in which the occluding member is located. 
     In still other embodiments, mechanical, adhesive or other means may be employed to secure the expanded occluding member  20  to the vessel wall defining the reproductive passageway  38 . For example, the means to secure a stent or prosthetic device to an aortic or arterial wall described in U.S. Pat. No. 4,140,126; U.S. Pat. No. 4,562,596; U.S. Pat. No. 4,577,631; U.S. Pat. No. 4,787,899; U.S. Pat. No. 5,104,399; U.S. Pat. No. 5,167,614; U.S. Pat. No. 5,275,622; U.S. Pat. No. 5,456,713; and U.S. Pat. No. 5,489,295 may be used with the present invention to interconnect the wall defining the reproductive tract and the expandable member. These patents are incorporated herein in their entireties by reference. 
       FIG. 19  illustrates one embodiment of invention having hook members  50  on the occluding member  20 . The hook members  50  spread radially outward from the longitudinal axis of the occluding member  20 , so that they contact the wall defining the reproductive tract as the occluding member expands therein. Thus, the hook members  50  become embedded in the wall defining the reproductive tract to anchor the occluding member  20  therein. In the embodiment illustrated in  FIG. 19 , the hook members  50  are located on the distal and proximal ends of the occluding member  20 , although other suitable configurations exist including hook members  50  which are disposed along all or part of a length of the occluding member  20 . A variety of suitable means may be used to attach the hook members  50  to the occluding member  20 , such as welding or brazing. Alternatively, as shown, they are attached to a connecting member  51  which is attached to the occluding member  20 . 
     Various modifications and improvements may be made to the present invention without departing from the scope thereof. For example, a mechanical expandable member such as described in U.S. Pat. No. 4,585,000, which is incorporated herein by reference, may be used to expand the expandable member within the reproductive tract to engage the wall thereof. Moreover, although individual features of embodiments of the invention may be shown in some of the drawings and not in others, those skilled in the art will recognize that individual features of one embodiment of the invention can be combined with any or all the features of one or more of the other embodiments.