Method and apparatus for clamping tissue layers and occluding tubular body structures

Apparatus and methods for occluding hollow body structures, such as blood vessels, and for attaching tissue layers together by providing implantable elements on opposite sides of the structure or tissue layers and drawing the implants together to occlude the body structure and/or bring the tissue layers together. The implants are deliverable in a low profile configuration and self-expand to an enlarged configuration. The implantable elements are delivered by transfixing the body structure, then releasing the implants on opposite sides of the body structure and drawing the implants together to effect an occlusion or attachment. The implants are configured to apply oppositely directed forces to opposite surfaces of the tissue layers at alternate, circumferentially spaced locations and may constrain the tissue in a serpentine pattern or in a direct clamping pattern. The implants grip the tissue in a manner that defines a pressure zone about the transfixion aperture that prevents leakage from the aperture.

FIELD OF INVENTION

The invention relates to methods and devices for the occlusion of blood vessels and other tubular body structures and for clamping tissue layers together.

BACKGROUND

There are numerous medical conditions and procedures in which it is desirable or necessary to occlude hollow or tubular body organs such as, for example, blood vessels or to clamp together layers of tissue. One such example is in the treatment of venous complications, such as varicose veins, in which treatment involves selective occlusion of the veins. Other ducts, vessels or hollow body organs also may have to be obstructed or tissue layers clamped together for a variety of reasons. It would be desirable to provide devices and methods to effect occlusions of hollow body organs and to secure tissue layers to each other in a manner that that is easy and quick to apply.

SUMMARY

The present invention provides a new and improved minimally invasive approach for occluding tubular body structures such as, for example, for treating varicose veins and other blood vessels where occlusion of the vessel or organ is an appropriate remedy.

More particularly, the inventions comprise the provision and use of an occluder that is used to occlude a vessel so as to restrict blood flow through the vessel. It may be used, for example, to treat varicose veins below the point of occlusion. Significantly, the device is configured to be deployed using visualization as may be provided by ultrasound and/or other visualization apparatus (e.g., CT, MRI, X-ray etc.). As a result, the treatment may be provided in a doctor's office with minimal local anesthetic and effectively no post-operative care. The invention also may be utilized in other procedures under direct visualization (e.g., during “open” surgery) or under indirect visualization such as during laparoscopic surgery where visualization is provided through the use of a scope, or during percutaneous surgery where visualization is provided through the use of imaging apparatus such as an ultrasound imager, an X-ray imager, etc.

In one form of the invention, there is provided apparatus for occluding a blood vessel, the apparatus comprising: an occluder having two cooperative parts, each of which includes a plurality of legs configured to assume (i) a diametrically reduced configuration for disposition within the lumen of a tube, and (ii) a diametrically expanded configuration in which the legs are extended radially for disposition adjacent to the blood vessel, such that when the two parts of the expanded occluder are brought together in their diametrically-expanded configuration with the vessel between them so they can grip the vessel to occlude it. In one aspect of this form of the invention the legs of the two parts are in registry when they grip the vessel. In another aspect of this form of the invention, the legs of the two parts of the occluder are interdigitated when they grip the vessel.

In another aspect of the invention, a method for occluding a blood vessel is provided in which opposing walls of the vessel are clamped directly together and in which the clamping is effected directly along a plurality of radially extending lines that extend outwardly from the axis of the occluder. In another aspect of the invention the opposing walls are bought together by constraining them in a serpentine pattern characterized by a series of reversing bends that extend circumferentially about the occluder axis. In a further aspect of the invention a clamping or occlusion device is provided in which the tissue is transfixed but in which leakage of fluids (e.g., blood) from the transfixion puncture is minimized.

ILLUSTRATIVE EMBODIMENTS

FIG. 1shows an embodiment of a two-part occluder200formed in accordance with the present invention. Two-part occluder200generally comprises a distal implant205and a proximal implant210. The occluder functions by compressing and securing the opposed walls of the vessel together. In one embodiment, distal implant205, shown in further detail inFIGS. 2-6, comprises a body215comprising a tube225having a distal end226, a proximal end227, and a lumen230. A locking tube220is located within lumen230of the body215. The tubular body215is slit intermediate its length so as to define a plurality of segments that, when the body is axially collapsed, will deform to define a plurality of radially extending legs235. Distal implant body215preferably is formed out of an elastic material (e.g., a shape memory material having superelastic properties such as Nitinol or superelastic polymers, including superelastic plastics) and constructed so that the legs235normally are bent and project laterally away from the longitudinal axis of tube225(e.g., in the manner shown inFIGS. 2 and 3). Due to the elastic nature of the material used to form distal implant body215, legs235can be deformed to a tubular, substantially linear, low profile shape so that they can be constrained within the lumen of a delivery tube or needle. See, for example,FIG. 5, which shows legs235moved inwardly toward a low profile relative to the position shown inFIGS. 2 and 3. However, when the constraint is removed, the elasticity of the material of the body215causes legs235to return to their relaxed, expanded position shown inFIGS. 43 and 44.

The lower, distal end250of the locking tube220is secured to the lower end of the body215as by spot welds applied via openings270formed in the distal end226of distal body215so that distal body and locking tube form a singular structure (seeFIGS. 3 and 5). This enables the proximal end227of the tubular body215to move longitudinally in a distal direction along the locking tube. When distal implant205is in its substantially linear, low profile condition (i.e., with legs235restrained in an in-line condition), distal implant locking tube220terminates well short of tangs240formed in the distal implant body215, so that the proximal end227of distal implant body215can move longitudinally relative to distal end226of distal implant body215.

The distal implant includes an arrangement by which it can be locked in the radially expanded configuration shown inFIG. 2. To that end, inwardly projecting tangs240are formed in tube225near the proximal end227. Tang-receptive windows265are formed in the proximal region of the locking tube220. The tangs and windows are positioned so that when the proximal end227of body215is moved distally a sufficient distance to allow full radial expansion of legs235(seeFIG. 1), locking tangs240of distal implant body215will be received within windows265of the locking tube220to lock distal implant205in its radially-expanded condition (FIGS. 2 and 3).

FIGS. 6 and 7illustrate the proximal implant210that comprises a tube275having a distal end280, a proximal end285, and a lumen290adapted to receive the proximal end227of the tubular body215of the distal implant205. Tube275is slit at its distal end to define a plurality of legs295. One or more inwardly projecting tangs300are formed in tube275adjacent its proximal end285. Proximal implant210is preferably formed out of the same or similar material as the distal implant and is constructed so that its legs295normally project laterally away from the longitudinal axis of tube275(e.g., in the manner shown inFIG. 6). Legs295can be constrained inwardly to a low profile configuration so that proximal implant210can assume a substantially linear disposition to be contained within the lumen of a delivery tube. See, for example,FIG. 7, which shows legs295moved inwardly relative to the position shown inFIG. 6. However, when the constraint is removed, the elastic nature of the material causes legs295to return to the expanded position shown inFIG. 6.

The distal and proximal implants205,210can be mated (with tube225of distal implant body215being received in lumen290of proximal implant210) so that the expanded legs235of distal implant205oppose and are in registry with the expanded legs295of proximal implant210(see, for example,FIGS. 52 and 52A). That arrangement imposes a direct clamping action on a blood vessel (e.g., vein) or other tissue disposed between the registered legs to occlude the blood vessel. In that mode of clamping the walls of the vessel are pressed together along a series of circumferentially spaced, radially extending lines. In another aspect of the invention, the proximal and distal implants may be arranged so that the legs of one are interdigitated with the legs of the other which imposes a different, serpentine, clamping configuration. Interdigitation refers to an arrangement that, when the proximal and distal implants are connected the legs295of the proximal implant will overlie the spaces between the legs235of the distal implant (or vice versa), as discussed in further detail below. The distal implant205and proximal implant210are configured to lock together in a clamped position by cooperative engagement of tangs300of proximal implant210and tang-receptive windows245of distal implant205.

Two-part occluder200may be deployed using associated installation apparatus that comprises a hollow needle305(FIG. 8) for penetrating tissue, a distal implant delivery tube310(FIG. 9) that extends through the needle, for delivering distal implant205through hollow needle305to the far side of the blood vessel which is to be occluded, a composite guidewire315(FIGS. 10-15) having a selectively expandable distal tip for providing support to various components during delivery and deployment, and a proximal implant delivery tube330(FIG. 17) for delivering proximal implant210and for mating with distal implant205, as discussed below. The installation apparatus also may include a separate tubular push rod320(FIG. 16) that is used in deployment of both the distal and proximal implants.

Hollow needle305(FIG. 8) has a distal end335, a proximal end340and a lumen345. Distal end335terminates in a sharp point350. Hollow needle305may comprise a side port355that communicates with lumen345. Distal implant delivery tube310(FIG. 9) has a distal end360, a proximal end365and a lumen370. Composite guidewire315(FIGS. 10-15) comprises a guidewire rod370and a guidewire sheath380. Guidewire rod370has a distal end385and a proximal end390. Distal end385terminates in an enlargement395. Guidewire sheath380comprises a distal end400, a proximal end405and a lumen410that receives the guidewire rod370. The distal end400of guidewire sheath380has at least one, and preferably a plurality of, proximally extending slits415that are open on the distal end of guidewire sheath380and allow the distal end of guidewire sheath380to expand radially when guidewire rod370is urged proximally within the sheath380. Tubular push rod320(FIG. 16) has a distal end420, a proximal end425and a lumen430. Proximal implant delivery tube330(FIG. 17) has a distal end435, a proximal end440and a lumen445.

Two-part occluder200and its associated installation apparatus are used as follows. First, hollow needle305carrying distal implant delivery tube310therein, which in turn contains the composite guidewire315upon which is mounted distal implant205is passed through the skin of the patient, through intervening tissue, and across the blood vessel (e.g., vein450) that is to be occluded (FIGS. 18-20). As this is done, any blood flowing out side port355can be monitored—excessive or pulsatile blood flow can indicate that hollow needle has accidentally struck an artery. Next, hollow needle305is retracted, leaving distal implant delivery tube310extending across the blood vessel (FIG. 21). The distal implant delivery tube310then is retracted partially to expose the distal ends of composite guidewire and distal implant205(FIG. 22). Next, push rod320is advanced over composite guidewire315to advance the distal implant205and composite guidewire315out of the distal end of distal implant delivery tube310. As this occurs, legs235of distal implant205are released from the constraint of distal implant delivery tube310and its legs expand radially as shown inFIGS. 23 and 24. Then, with push rod320being held in place against the proximal end of distal implant205, composite guidewire315is expanded at its distal end and is pulled proximally so as to bring the distal and proximal implants together until locking tangs240of distal implant body215engage windows265of the locking tube220, thus securing the expanded implants together (FIG. 25). At this point, hollow needle305, distal implant delivery tube310and push rod320may be removed (FIG. 26), leaving distal implant205mounted on composite guidewire315, with the legs235fully deployed on the far side of the blood vessel and the proximal end of distal implant205extending into the interior of the blood vessel (FIG. 27). Thus, in the placement of the device the vessel or tissue is pierced (transfixed). Notwithstanding the transfixion, the legs close the vessel or tissue to prevent flow and, therefore, there is no or minimal leakage of blood from the transfixion aperture. This may be contrasted with use of staples or sutures to occlude vessels or clamp tissue in which loss of blood through the puncture holes is a common problem.

With the distal implant so placed and deployed, the proximal implant delivery tube330(carrying proximal implant210therein) is advanced over and along composite guidewire315, until the distal end of proximal implant delivery tube330sits just proximal to the blood vessel (FIGS. 28-31). Push rod320then is used to advance the distal end of proximal implant210out of the distal end of proximal implant delivery tube330. As this occurs, legs295are released from the constraint of proximal implant delivery tube330and open radially (FIGS. 32-35). Then, using push rod320, proximal implant210is pushed distally along the guidewire as distal implant205is pulled proximally using composite guidewire315, the distal end of the guidewire sheath380being enlarged by enlargement395. As distal implant205and proximal implant210are drawn together, their legs235,295cooperate to compress the blood vessel, thereby occluding it. Distal implant205and proximal implant210continue moving together until inwardly-projecting tangs300of proximal implant210enter windows245of distal implant205, thereby locking the two together as shown inFIG. 36. At this point push rod320and proximal implant delivery tube330are removed. SeeFIG. 37. Next, composite guidewire315is removed by first advancing guidewire rod370distally (FIG. 38) to enable the sheath to contract to its smaller diameter. to a size smaller than lumen262in distal implant locking tube220. Guidewire sheath380and rod then can be withdrawn proximally through the interior of two-part occluder200(FIG. 39). The foregoing procedure leaves two-part occluder200locked in position across the blood vessel, with the opposing legs235,295compressing the blood vessel, whereby to occlude the blood vessel. It should be understood that the composite guidewire315may take other forms that also serve to detachably bind to the distal implant such as, for example, providing threads on the end of the guidewire to cooperate with a threaded recess on the distal implant to connect releasably the distal end of the guidewire to the distal implant.

In practicing the invention the legs of one or both of the implants may be arranged to expand generally perpendicular to the axis of the occluder or may be arranged to extend at an acute angle to the longitudinal axis of the implant such that the legs on one or both of the implants collectively define a cone-like concave region (e.g., at301E inFIG. 44). The angle defined by the cone-like shape is referred to as the “cone angle” and may be varied to provide for different device characteristics. The arrangement may be varied such that when both implants include legs defining the concave regions the concave regions may face each other (FIG. 42) or may face in the same direction (FIG. 46) in a somewhat nesting configuration.

FIGS. 42-45illustrate another form of the invention embodying an arrangement in which both the distal and proximal implants can be stored in and delivered through the same delivery tube or needle rather than separate proximal and distal implant delivery tubes. Additionally, this embodiment illustrates a separate and alternative arrangement for securing the proximal and distal implants together. In this embodiment locking tube220E of the distal implant is provided with one or more longitudinally spaced circumferential grooves or recesses265E formed along its length. As with the previously described embodiment, locking tube220E is secured at its distal end to the distal end of the distal implant body215E as by spot welding, adhesives, mechanical interlocks, etc. Instead of the arrangement of a composite guidewire to retain the distal implant, the proximal end of the locking tube220E also comprises a first half266E of a mechanical interlock by which the locking tube220E (and hence distal implant205E) can be connected to a distal implant retention tube310E that has a mating second half361E of the mechanical interlock as described below. The mechanical interlock enables the distal implant to remain attached to the deployment device until the proximal implant has been deployed and secured to the distal implant, as described below. As shown inFIGS. 48-50, the halves of the interlock266E comprise a stepped configuration433E,434E, they being complementary so as to mate together. Although we have found that the connection tends to stay together, a locking rod436E may be passed through the interlock to further secure the connection. The rod must be removed or withdrawn before separation of the interlock components. Alternatively, internal locking rod436E may be replaced by an overtube (not shown) which telescopically projects over distal implant delivery tube310E and distal implant locking tube220E of distal implant205E, whereby to enhance the connection between the members.

Locking tube220E preferably is formed out of the same or similar material as described above. By way of example but not limitation, distal implant locking tube220E may be formed out of a titanium alloy such as Ti 5 AL-4V or Nitinol.

In the embodiment ofFIGS. 42-45inwardly projecting tangs300E are formed in tube275E of the proximal implant for engaging the grooves or recesses265E in distal implant locking tube220E. If desired, the locations and configurations of grooves or recesses265E and tangs300E can be reversed, i.e., outwardly-projecting tangs300E can be provided on locking tube220E and grooves or recesses265E can be provided on the inner side wall of tube275E, or other means can be provided for connecting tube275E of proximal implant210E to locking tube220E of distal implant205E. The positions of circumferential grooves or recesses265E of locking tube220E and inwardly-projecting tangs300E of proximal implant210E are coordinated so that when they engage legs235E of distal implant205E and legs295E of proximal implant210E are sufficiently close to ensure adequate clamping of a blood vessel (or other tubular structure) disposed therebetween.

The manner in which the occluder200E may be deployed is illustrated in the context of a laparoscopic procedure using a laparoscopic device331E. A similar arrangement may be used for percutaneous delivery. First, hollow needle305E containing both the distal and proximal devices, longitudinally spaced within the needle lumen, is advanced to the occlusion site, for example, while needle305E is contained within sheath333E of the delivery device331E (FIG. 73). In a percutaneous procedure the needle would be inserted directly without a sheath. The spacing between the implants within the needle is greater than the thickness of the vessel or tissue that is to be clamped. Then, sheath333E is retracted to expose the needle, e.g., by turning knob334E and the needle305E is passed transversely through the walls of the blood vessel (e.g., a vein) which is to be occluded or passed through tissue or objects to be secured to one another, such as a solid organ, or layers of tissue, etc. At this point in the procedure, the implants are within the needle but on opposite sides of the vessel or tissue to be clamped. The distal implant is connected, at its mechanical interlock, to the distal end of the distal implant retention tube310E. The proximal implant is slidably disposed about the distal implant retention tube310E. Next, hollow needle305E is retracted proximally, back across the blood vessel, e.g., as by operating first trigger336E (FIG. 73) to progressively expose the distal implant and to allow legs235E of distal implant205E to expand radially on the far side of the blood vessel. The distal implant is held in place by its connection with the retention tube. At this point, distal implant locking tube220E extends proximally through the blood vessel.

Then, with retention tube310E held in place, hollow needle305E is withdrawn further proximally (e.g., via first trigger336E) until proximal implant210E is exposed and is no longer constrained within hollow needle305E (FIG. 74). As this occurs, legs295E of proximal implant210E are released fully from the constraint of hollow needle305E and open.

Proximal implant delivery tube330E then is advanced distally along and about the retention tube310E, (e.g., using second trigger337E), to push the proximal implant210E toward distal implant205E (FIG. 75). As distal implant205E and proximal implant210E are drawn together, their legs235E,295E compress the blood vessel therebetween, thereby occluding the blood vessel. Distal implant205E and proximal implant210E continue moving together until inwardly-projecting tangs300E of proximal implant210E enter circumferential grooves or recesses245E of distal implant205E, thereby locking the two members into position relative to one another. Proximal implant delivery tube330E is withdrawn (FIG. 76), retention tube310E is released from distal implant205E (i.e., by using lever338E) to unlock the second half361E of the mechanical interlock from the first half266E of the mechanical interlock, and then the installation device is withdrawn (FIG. 77).

The foregoing procedure leaves two-part occluder200E locked in position across the blood vessel, with the opposing legs235E,295E compressing the blood vessel therebetween, whereby to occlude the blood vessel.

In the preceding disclosure, two-part occluder200E is discussed in the context of using the elasticity of its legs235E,295E to cause its legs235E,295E to reconfigure from a diametrically reduced configuration (e.g., when constrained within a delivery needle) to a diametrically expanded configuration (e.g., when released from the constraint of a delivery needle). However, it should also be appreciated that where legs235E,295E are formed out of a shape memory material (e.g., Nitinol), a temperature change may be used to reconfigure legs235E,295E from a diametrically-reduced configuration to a diametrically-expanded configuration. By way of example but not limitation, in this form of the invention, legs235E,295E may be constructed so as to have a diametrically reduced configuration when maintained at a temperature below body temperature, and legs235E,295E may be constructed so as to have a diametrically expanded configuration when maintained at body temperature. As a result, by cooling two-part occluder200E to a temperature below body temperature, inserting the two-part occluder into the body, and then allowing the two-part occluder to heat to body temperature, legs235E,295E can be caused to reconfigure from their diametrically-reduced configuration to a diametrically-expanded configuration.

Although the system has been described primarily in connection with a percutaneous delivery device, the installation apparatus can be adapted for use in laparoscopic, endoscopic or open surgical procedures, as by associating the components of the delivery system (a hollow needle, distal implant delivery tube, a composite guidewire or equivalent, a tubular push rod and a proximal implant delivery tube) with an appropriate handle at the proximal end of the system for controlling the operation of the components.

Although the two-part occluders discussed above rely on the superelasticity of the material to cause the legs of the implants to self-expand when released from the delivery tube, it should also be appreciated that where legs235E,295E are formed out of a shape memory material (e.g., Nitinol), a temperature change may be used to reconfigure legs235E,295E from a low profile, diametrically reduced configuration to a diametrically expanded configuration. By way of example but not limitation, in this form of the invention, legs235E,295E may be constructed so as to have a diametrically reduced configuration when maintained at a temperature below body temperature but to have a diametrically expanded configuration when maintained at body temperature. As a result, by cooling two-part occluder200E to a temperature below body temperature, inserting the two-part occluder into the body, and then allowing the two-part occluder to heat to body temperature, legs235E,295E can be caused to reconfigure from their low profile, diametrically reduced configuration to a diametrically expanded configuration.

FIG. 46-47show another two-part occluder200E similar to that described above except that legs235E of distal implant205E, and legs295E of proximal implant210E, have their concavities facing in the same direction, so that legs235E,295E nest with one another rather than confront one another. In addition, as seen inFIGS. 46-47, tube225E of distal implant205E is partially received in lumen290E of proximal implant210E.

FIGS. 48-50illustrate the releasable mechanical interlock for connecting the distal implant to distal implant retention tube310E. As shown inFIGS. 48-50, the first half266E of the mechanical interlock carried by the proximal end of locking tube220E comprises a stepped configuration433E, and the second half361E of the mechanical interlock carried by the distal end of distal implant delivery tube360E comprises a mateable, complementary stepped configuration434E. With the complementary parts engaged, the connection may be secured by placing a locking rod436E through central lumen437E of distal implant retention tube310E and into lumen262E of implant locking tube220E. Alternatively, in another form of the invention, internal locking rod436E may be replaced by an overtube (not shown) that can be placed over the engaged distal implant retention tube310E and locking tube220E to prevent, temporarily, their separation.

It should also be appreciated that other forms of temporary mechanical interlocks may be used for releasably securing distal implant205E of the two-part occluder200E ofFIGS. 46 and 47to distal implant retention tube310E. By way of example but not limitation, a screw interlock may be used, e.g., the first half266E of the mechanical interlock (carried by the proximal end of distal implant locking tube220E) may comprise a threaded bore, and the second half361E of the mechanical interlock (carried by the distal end of distal implant delivery tube360E) may comprise a threaded post, wherein the threaded post carried by the distal end of distal implant delivery tube360E may be received in the threaded bore of distal implant locking tube220E. Alternatively, other configurations of a screw interlock may be used, or other forms of mechanical interlocks may be used. In still another variation the locking tube220E can be formed integral with distal implant retention tube310E, with a weakened section disposed at their intersection, and with the two members being separable a mechanical breaking action.

It will be appreciated that, in certain circumstances, it may be desirable to increase the surface area of those portions of the occluder that contact the tubular body structure, in order to better distribute the load applied to the tissue. In this situation, it can be helpful to increase the width of the legs (e.g., legs235E and/or legs295E of two-part occluder205E, etc.), and/or to provide flexible material in the zone between adjacent legs (e.g., in the manner of an umbrella) so that the flexible material can also carry load (i.e., essentially increasing the effective width of legs235E and/or legs295E). See, for example,FIG. 51, which shows flexible material438E extending between legs235E and legs295E.

The relative orientation of the legs of the proximal and distal implants may be selected to provide different clamping patterns, the selection of which may depend on the particular anatomy and characteristics of the tissue with which it is to be used. In one configuration, as described above and as shown diagrammatically inFIGS. 52A and 52B, the legs295of the proximal implant are arranged to be in registry with some or all of the legs235on the distal implant such that pairs of proximal and distal legs295,235will cooperate to directly compress the vessel or other tubular body structure or tissue along a series of angularly spaced, radial extending clamping lines CL as suggested diagrammatically inFIG. 52. It may be noted that although the direct clamping tends to cause the opposing walls of the vessel to contact each other between the clamping lines as well as along the clamping lines CL, in some cases direct contact may not occur in one or more regions between the clamping lines CL. However, even where some such regions may exist, the arrangement of multiple, angularly spaced direct clamping lines provide enough obstruction to the lumen to cause effective occlusion.

FIGS. 53 and 53Aillustrate another arrangement of the legs295,235of the proximal and distal implants in which the legs are interdigitated so that they do not effect a direct clamping of the tissue but, instead, engage the tissue to constrain the tissue in a serpentine configuration extending at least partly about the axis of the occluder in a generally circumferential direction. In an interdigitated arrangement, the legs of one of the implants are out of registry with those of the other implant so that when viewed in plan, the legs of one implant lie between the legs of the other. In particular, arranging the legs in an interdigitated array is considered to allow a tubular structure to be safely occluded in a way that avoids leakage problems associated with staples or conventional clips (e.g., hemoclips, Ligaclips, etc.). In an interdigitated configuration the opposing walls of the vessel are together partially wrapped about the legs in alternating directions to constrain the tissue in a serpentine configuration as seen diagrammatically inFIG. 53A. Additionally, interdigitation provides an additional means by which the clamping forces can be adjustably controlled. By selecting a particular cone angle defined by the expanded legs, coupled with the dimensions and positioning of the mechanical locking mechanism by which the relative position of the legs of the deployed occluder are determined, the characteristics of the serpentine pattern can be determined. Cone angle selection also may be used to control the degree of compression between the legs of the implants in the direct clamping embodiment ofFIGS. 52, 52A.

FIG. 54shows a two-part occluder200and illustrates further the manner in which the legs295of the proximal implant210are interdigitated with the legs235of the distal implant205. When interdigitated, the outer free ends of the legs of each, in the absence of engaged tissue, intersect a plane defined by the free ends of the other, a condition that may be referred to as “overlap”. If desired, the degree of overlap (and, therefore, the degree of interdigitation) may be designed into the device by selecting the cone angle for the legs and the location of the locking mechanism for the implants.

Another variable that may be used to control the manner in which the occluder engages the tissue is to vary the angular offset between the legs of the proximal and distal implants. Variable offset between legs235and legs295allows for the adjustment of clamping tension applied to the tissue. For example, for delicate or easily damaged or torn tissue (e.g., brain tissue), or tissue that has limited elasticity, it is believed to be generally preferable that legs235and legs295are out of alignment to constrain the tissue in serpentine pattern (interdigitation) so that no direct compression is applied to the tissue. The cooperative tangs and windows or detents and grooves265may be arranged to provide for a selected degree of overlap and interdigitation. In the arrangement of tangs and windows there may be one or several circumferentially spaced windows by which the angular orientation of the legs of the implants can be varied when locked.

FIG. 55shows three photographs of a two-part occluder200with interdigitated legs effectively clamping a simulated blood vessel. The interdigitated legs cause serpentine ripples, or folds, in the tissue that act to extend the effective closure, and causes closure of the vessel well beyond the region directly contacted by the occluder legs235,295. This is believed to result because the serpentine pattern extends radially somewhat beyond the periphery defined by the implant legs. By way of example but not limitation, a two-part occluder200having a physical occlusion diameter of 5.5 mm is able to close vessels that are over 7 mm (and even equal or greater than 1 cm) in diameter.

It should be understood that when an interdigitated device is locked into engagement with tissue, the thickness or nature of the tissue may cause the legs to flex to an extent that the degree of overlap is reduced or the legs may no longer overlap at all. Even when this occurs the legs of the proximal and distal implants still apply forces to the tissue that alternate in proximal and distal directions with the legs of the proximal implant applying distally directed forces and the legs of the distal implant applying proximally directed forces. These opposed forces of the implant legs, applied alternately at circumferentially spaced locations about the center of the occluder, are effective to secure tissue layers together or to occlude a lumen.

Additionally, we have found that even when the legs of the proximal and distal implants are initially in registry, when the implants are urged together and locked in very close proximity to each other, the initially registered legs can flex into a non-registered configuration in which the legs may be interdigitated and/or may apply oppositely directed forces to the tissue at circumferentially spaced locations about the center of the occluder as described above,

The legs295,235of the proximal and distal implants210,205may be beveled (or rounded) so that they do not present sharp edges, and legs295,235may be designed to separate slightly from the tissue at the free end of each leg. This is in order to minimize any catching or damage that may be imparted on the tissue by legs235,295, whereby to minimize tearing or ripping of the tissue. In other embodiments of the present invention, it may be desirable to provide sharp features to legs235,295so that legs235,295catch or pierce the tissue for better gripping. Legs235,295may be provided with smooth surfaces or may be roughened, as by chemical etching or mechanical means, so as to enhance the imaging reflectivity of the implants, or to provide increase tissue capture and gripping.

The two-part occluder as described may be configured to occlude blood vessels under fluid pressures of at least 100 mm Hg and up to 300 mm Hg. Occluders also may be made that are capable of resisting pressure of over 700 mm Hg.

FIG. 56shows one embodiment of the present invention wherein distal implant locking tube220comprises a controllable ratcheting mechanism for selectively controlling the spacing between proximal implant210and distal implant205when they are secured together. In this form of the invention, legs235of distal implant205and legs295of proximal implant210may be generally oriented primarily in a parallel registered orientation to each other. In this form of the invention, locking tube220comprises a plurality of windows265(or circular grooves) formed along its length. Proximal implant210comprises one or more inwardly projecting tangs300formed at a point along its length. As proximal implant210is advanced distally towards distal implant205, inwardly projecting tangs300enter into windows265, thereby locking proximal implant210to distal implant205. Inwardly projecting tangs300are configured so that proximal implant210can only move in a single direction (i.e., distally) relative to distal implant205. As proximal implant210is advanced distally relative to distal implant205, inwardly projecting tangs300can slide out of windows265and enter the next distal window265. If desired, windows265may comprise a chamfered distal edge to facilitate movement of inwardly projecting tangs300out of windows265as proximal implant210moves distally relative to distal implant205.FIG. 56shows another variation in which the “notch-to-notch distance” (i.e., the distance between windows265) governs the ability to vary the degree of compression established between legs235of distal implant205and legs295of proximal implant210.

FIGS. 57 and 58illustrate the a manner in which the rotational orientation of the proximal and distal implants and, therefore, their respective legs may be set. In the example shown, one or more alignment grooves (or notches)605may be formed in the proximal end of proximal implant210, and one or more corresponding orientation alignment post (or tab)610may be formed in the distal end of the pusher tube for selective engagement with the grooves or notches605. The relative orientation of the proximal implant210and the distal implant205thus can be varied by selectively engaging the grooves and posts and rotating the proximal implant relative to the distal implant until the desired angular orientation is achieved. The procedure can be done under visualization as described above. Alternately, the relative orientation may be adjusted by using the retention tube to rotate the distal implant relative to the proximal implant.

In another modification, the orientation of the legs can be predetermined by providing a slot and groove arrangement between the proximal and distal implants to assure that they can be locked together only in a desired relative angular orientation. Thus the disposition of legs235of distal implant205relative to the disposition of legs295of proximal implant210may be controlled so as to apply a desired clamping force according to the type and/or condition of the tissue that is to be clamped.

When the two-part occluder is arranged with its legs interdigitated, the wall thickness of the vessel to be occluded or the tissue layers to be joined does not necessarily determine whether an effective occlusion or attachment can be achieved. As long as the interdigitation of the legs constrains the vessel walls in a serpentine pattern or the forces are alternately applied in proximal and distal directions circumferentially about the center of the occluder the walls of the vessel will may be brought into contact with each other sufficiently to occlude the vessel, even when the legs235and legs295may not cross each other's plane (“overlap”) regardless of the summed wall thickness of the vessel. Thus, vessels, of varying dimensions can be effectively occluded. Whether and to what extent the legs of the proximal and distal implants may overlap will depend on the characteristics and dimensions of the anatomy to be occluded and the configuration for the implants necessary to constrain the tissue in a serpentine configuration.

Where legs295,235of the proximal and distal implants210,205are interdigitated, the serpentine constraint of the tissue layers reduces the force needed to occlude the vessel and is considered to be much less than the force needed to close the same vessel with a conventional ligation clip.FIG. 59is a photograph of a histological section of tissue from a vessel occluded with an interdigitated occluder and showing the serpentine pattern of the tissue layers of the vessel walls after healing of up to 30 days. The vessel is completely occluded and the vessel wall tissue is compressed and adhered to itself in the serpentine configuration. The “pie crust” or serpentine closure may be observed more clearly as well. The arrow indicates the collapsed undulating artery. AVO indicates the location of the interdigitating legs of two-part occluder200.

The two-part occluder200of the present invention may be used to occlude vessels, ducts and/or to compress tissue so it is occluded/compressed at forces less than 700 grams, while the force required to seal off vessels or clamp tissue with a commercially available Ligaclip are about ten times greater. The two-part occluder200of the present invention can maintain operation within the range of elasticity of the material and does not need to be plastically deformed to realize occlusion.

It will be appreciated that the occluder of the present invention can also be used to occlude tubular and hollow structures other than blood vessels. By way of example but not limitation, the temporary occluder of the present invention can be used to occlude fallopian tubes, vas deferens, ducts, as the bile duct and cystic ducts for cholecystectomy, lymphatic vessels, including the thoracic duct, fistula tracts, etc. The present invention can also be used to bring, attach and/or connect at least two folds (e.g., two sides of the stomach, or other parts of the legs, etc.) together so that they are connected.

In addition to occluding blood vessels the occluders can be used for clamping and compressing regions of resected organs so as to reduce or stop blood flow or blood loss after surgery. For example, as shown inFIG. 60the occluder may be used in solid organ resection of the kidney or liver or other organs. Blood loss and secretion leakage (e.g., bile, urine, etc.) can be problematic in existing solid organ resection procedures. Average blood loss for a liver resection is 700-1200 ml. By clamping desired regions of the solid organ with one or more occluders, it is possible to significantly reduce the amount of undesirable fluid loss (blood loss, secretion leakage, etc.). The occluder can be used to apply pressure selectively to broad areas of the organ and, additionally, may also be used to close off selective tubular structures and vessels connecting the organ with other regions of the body. Multiple discrete occluder elements may be deployed across regions of the organ as suggested inFIG. 60. Where multiple, single, separate puncture placements of the occluder are used, different regions of the solid organ may be compressed to different and controllable degrees.

Although described in the context of occluding blood vessels, the present invention may be practiced under direct visualization (e.g., during “open” surgery) or under indirect visualization (e.g., during laparoscopic surgery where visualization is provided through the use of a scope, or during percutaneous surgery where visualization is provided through the use of imaging apparatus such as an ultrasound imager, an X-ray imager, etc.).

The present invention can be used for occlusion of tubular structures such as veins, arteries, bile ducts, fallopian tubes, cystic ducts, etc.

The present invention can also be used to connect tissue with other materials, e.g., graft materials, hernia meshes, drug delivery materials, etc.

FIG. 61shows a two-part occluder200and its surrounding effective pressure zone. Note that the different overlaps between legs295of proximal implant210and legs235of distal implant205are controllably adjustable to provide the desired pressure zone and occlusion level. The legs also may be formed to have different and varying widths.

In one form of the present invention, the pressure zone (the area in which the tissue layers are urged into contact) generated by two-part occluder200is a generally circular area extending around the entry point of the transfixing distal locking tube220(FIG. 62), but in other embodiments the pressure zone may be non-circular, meaning that the lengths of legs235of distal implant205and legs295of proximal implant210are not equal. For example, an oval pressure zone may be employed with legs of unequal or asymmetric length, so that the occluder200can be positioned proximal to a branched vessel or tissue, as shown inFIG. 63. In one form of the present invention, the orientation of the proximal and distal implants of two-part occluder200can be determined using markings disposed on the delivery device handle (e.g., an arrow which indicates the long direction of legs235,295). In laparoscopic or open procedures, the orientation of two-part occluder200can also be visually confirmed. In percutaneous applications, ultrasound, or CT imaging can be used to further determine orientation of two-part occluder200relative to vessels, ducts, organs, tissue that is are to be clamped or occluded.

FIGS. 64-72illustrate the components of a modified occluder having a locking mechanism of tangs and windows that assures locking of the implants when they are brought together, regardless of their orientation. In this arrangement the distal implant can be laser cut with one or more windows circumferentially spaced about the hollow tubular section of the implant. The mating proximal implant can be cut to include one or more tangs, each tang configured to engage a window, thereby locking the two occlusion elements together. In the embodiment ofFIGS. 64-72, the tangs and windows are designed to lock together regardless of the angular orientation of the legs of the implants (a feature referred to as “angular relation indifference.”

FIG. 64shows a distal implant722with three windows771(only two visible) that are spaced evenly around the circumference of the occlusion element722, located proximal to the legs. A portion775of the tube separates and frames each pair of adjacent windows771. In the embodiment shown, each of the three windows771occupies approximately 80 degrees of the circumference of the tube, and each window frame portion775occupies approximately 40 degrees of the circumference of the tube. It should be understood that other arrangements and sizes of windows are possible that will still achieve the angular relation indifference configuration.

FIG. 65shows a proximal implant724with four inwardly projecting tangs781, only two of which are visible in the drawing. Despite the different numbers of windows771and tangs781,FIGS. 66-72illustrate how the distal implant722and the proximal occlusion element724will lock together, regardless of their angular orientation.FIG. 66shows the proximal implant724and the distal implant722locked together. The distal implant722has a smaller diameter than the proximal implant724and fits within the hollow tube of the proximal implant724. The two visible tangs781aand781bare both projecting inwardly into the corresponding windows771of the distal implant722, thereby locking them in place.FIG. 67shows a side view to more clearly show the inwardly projecting tangs781aand781blocked in place with respect to the windows771.

FIG. 68shows a sectioned view of the two implants locked together. Due to the different configurations of the tangs781and windows771(i.e., there are four tangs781a-dbut only three windows771a-c), tangs781cand781ddo not project into the windows771in the orientation shown. However, regardless of orientation of the two occlusion elements, at least one (and as many as two) of the four tangs will always be locked in place. That angular relation indifference is shown more clearly inFIGS. 70-72.

FIG. 69shows a close-up cross-section view of the two implants locked together. In this orientation, tang781ais locked in place in the window771defined by window frame elements775aand775b; and tang781bis locked in place in the window771defined by window frame elements775aand775c. Tangs781cand781dare not projecting into windows, but are instead contacting window frame elements775band775c, respectively.FIG. 70shows a slightly different orientation between the two elements. This orientation is rotated clockwise from the orientation shown inFIG. 70. InFIG. 70, tangs781band781cproject into windows771framed by elements775aand775b, and775band775c, respectively. Tangs781aand781dare in contact with window frame elements775aand775c, respectively.FIGS. 71 and 72show two other orientations, with the proximal occlusion element724rotated clockwise with respect to the preceding orientation. Regardless of how many degrees the proximal occlusion element724is offset from the distal occlusion element722(from 0-360 degrees), in any orientation there will always be at least one, and as many as two, of the tangs locked into one of the windows, due to the angular relation indifference configuration.

The tangs and windows may be configured to control the relative angular position of the legs of the proximal and distal implants. For example, the windows and tangs may be configured to engage only when the legs of the two implants are oriented in a specific angular relation. Thus, the legs of a distal occluder can be offset with respect to those of the proximal occluder to achieve an interdigitating configuration as discussed above. In other embodiments, it may be desirable for the legs to align so as to compress the structure between aligned legs. Other alignments may be preferable as well, including partially offset legs.

FIGS. 78-80illustrate, diagrammatically, another type of occluder800that may be formed from a wire of shape memory material, such as Nitinol and constrains the tissues in a serpentine pattern. The wire can be delivered through a needle or other delivery tube that is first advanced through the walls of the vessel or tissue layers, as described below. The wire may be maintained in a linear configuration by the lumen of the needle or delivery tube but reverts to its preformed “memorized” shape as it advances out of the needle. As shown inFIGS. 78 and 79the occluder, when fully released has a shape memory of a pair of spaced spiral coils802,804connected by an intermediate transluminal segment806. The spirals are generally similar and parallel each other except that the wire of one of the spirals overlies the spaces defined by the other spiral as shown, diagrammatically inFIG. 79. The transluminal segment806connects the inner most ends of the spirals802,804. It is relatively short to be able to span and extend through the compressed tissue and to space the spirals so that they engage the outer surfaces of the tissue and constrain the tissues in a serpentine pattern as illustrated inFIG. 80. The serpentine pattern is considered to effectively secure the tissue layers together with less force than is applied with a more conventional clamp. In the case of a blood vessel or other tubular body organ the occluder may be effective to occlude flow of blood or other fluid through the vessel. The device is delivered by first transfixing the vessel or tissue layers with the needle of delivery tube. Then, the distal portion of the wire is advanced out of the distal end of the needle or tube. Freed from its restraint, the distal portion of the wire self expands to the desired shape of the distal spiral. The needle or tube then is withdrawn to locate its distal tip on the proximal side of the vessel or tissue and then the proximal portion of the wire is released to form the proximal spiral, the transluminal portion extending transversely through the tissue. The wire composition and dimensions may be varied to suit varying anatomical considerations as will be appreciated by those skilled in the art.

In each of the foregoing embodiments the transfixion aperture that is formed by the device does not tend to leak blood (or other fluid) because the zone about the point of transfixion where the legs cooperate to prevent fluid flow substantially prevents fluid from reaching the aperture. Thus, the invention may be advantageous in many situations over other techniques in which blood loss may be problematic (e.g., staples, sutures, etc.)

Thus, it will be appreciated that the foregoing description provides devices and methods for occluding vessels and for clamping tissue layers that provide advantages over prior art techniques. Occluders and clamps are provided that employ a pair of components that are brought together on opposite sides of a vessel or tissue layers to compress the vessel walls or tissue layers. The clamping may be directly on the tissue or may be such as to constrain the tissue layers in a serpentine pattern that is considered to occlude or clamp with less direct compressive force on the tissue. Applying oppositely directed forces at alternating locations on the tissue circumferentially about the center of the occluder also may effect occlusion or clamping. The occluders may include pluralities of radially extending legs or spirally oriented elements that cooperate to effect occlusion or clamping. In each instance a pressure zone of occlusion is formed about the point of transfixion to prevent leakage through the transfixion aperture.

It should be understood, however, that the foregoing description of the invention is intended merely to be illustrative and that other embodiments, modification and equivalents may be apparent to those skilled in the art without departing from the principles of the invention.