MEDICAL PLUG
Background of the Invention
Th s invention relates to medical plugs, and more particularly to medical plugs which can be installed mtralumenally if desired. The invention also relates to methods and apparatus for delivering and installing medical plugs, especially mtralumenally if desired.
Increasing numbers and types of tralumenal procedures are being performed on medical patients. For example, there are mtravascular blood flow measurement procedures, balloon angioplasty procedures, mtravascuiar stent installation procedures, and even mtravascular coronary bypass procedures (see, for example, Goldsteen et al. U.S. patent application No. 08/745,618, filed November 7, 1996, which is hereby incorporated by reference herein) . These procedures may involve putting one or more holes in the walls of circulatory system vessels, and it may be necessary to thereafter plug those holes. Sorrt of these holes may be located very remotely from where the medical instrumentation enters the patient's body. Such holes may tnerefore only be conveniently reachable mtravascularly. The above-mentioned mtravascular procedures are only some examples of where plugs may be needed to plug noles body tissue walls. The side walls of
other tubular body organs may have holes that require plugging, and again it may be desired to deliver a plug to such a hole mtralumenally. Any other body tissue wall may also require a plug in a hole, and it may sometimes be necessary to deliver a plug to such a hole remotely and/or with convenient access to only one side of the tissue wall.
In view of the foregoing it is an object of this invention to provide improved medical plugs. It is a more particular object of this invention to provide medical plugs that can be installed mtralumenally and/or remotely if desired.
It is still another object of this invention to proviαe methods and apparatus for installing medical plugs.
It is yet another object of this invention to provide methods and apparatus for mtralumenally and/or remotely installing medical plugs.
It is still another object of this invention to provide etnods for making medical plugs.
Summary of the Invention
These and other objects of the invention are accomplished m accordance with the principles of the invention by providing medical plugs which have two relatively large end portions joined by a relatively small linking structure between the end portions. For example, the end portions may have the shape of two relatively large discs that are substantially parallel to and face one another. The linking structure between the discs has a relatively small cross section parallel to the planes of the discs. The linking structure is preferably connected to each disc near the center of the disc. The plug is installed in a hole in a body tissue wall with one of the end portions (e.g., one of
the discs) on one s ne of the wall, with the ether end portion (e.g., the other disc) on the other side of the wall, and with the linking structure passing through the hole. The end portions are preferably close enough to one another that they each bear on the adjacent body tissue wall surface. The plug preferably provides a fluid-tight seal of the hole in which it is installed.
A preferred construction of a plug of this invention includes an open framework of a first highly elastic material. For example, this framework may be a mesh made of nitmol. The framework is covered with a preferably continuous web of a second highly elastic material such as silicone.
A preferred method of installing a plug in accordance with this invention includes deforming the plug into a tubular shape that has a longitudinal axis substantially parallel to an axis passing through the linking structure between the two end portions m the undeformed plug. The tubular shape is then caused to pass axially part way through the hole to be plugged. The tubular shape is then released so that it can return to its undeformed shape with each end portion on a respective side of the body tissue wall that has the hole and with the linking structure passing through the hole between the end portions.
Apparatus for installing a plug m accordance with the above-described method may include a tubular mandrel around which the plug can be deformed into the above-mentioned tubular shape. A releasable retainer mechanism is used to releasably hold the plug on the mandrel in the deformed tubular shape. The mandrel and the tubularly deformed plug are inserted axially into the hole to be plugged. For example, this may be done mtralumenally by extending the mandrel through a catheter tube m a blood vessel or other tubular body
organ. The releasable retainer mechanism is then operated to release the plug from the mandrel as the mandrel is withdrawn from the hole. As the plug is released from the mandrel it returns to its undeformed shape and is left m the hole.
Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments.
Brief Description of the Drawings
FIG. 1 is a perspective view of an illustrative embodiment of a medical plug constructed in accordance with this invention.
FIG. 2 is an elevational view, partly section, of the plug of FIG. 1 installed in a hole in the wall of a patient's tubular body o'rgan.
FIG. 3 is a simplified perspective view of illustrative apparatus for installing the plug of FIGS. 1 and 2 m accordance with the invention.
Detailed Description of the Preferred Embodiments
An illustrative p iq 10 constructed _τ_ accordance with the invention is shown in FIGS. 1 and 2. FIG. 1 shows plug 10 by itself, while FIG. 2 shows plug 10 installed in a hole m a wall 22 of a patient's tubular body organ 20. For example, organ 20 may be the patient's aorta.
Plug 10 has two relatively large end portions 30 and 50 m the shape of hollow discs that are held together by a relatively small, intermediate linking structure 40. Discs 30 and 50 are preferably substantially parallel to one another and close together. Linking structure 40 is preferably disposeα
at the center of each disc 30 and 50. Although plug 10 may be made m any of a wide range of sizes, m an illustrative embodiment each of discs 30 and 50 is about 0.350 inches m diameter and about 0.035 inches thick. The cross section of linking structure 40 parallel to discs 30 and 50 is preferably about 0.030 to ar>out 0.060 inches. And the spacing between discs 30 and 50 (m the absence of any intervening body tissue) is preferably as small as possible (most preferably about 0.0 inches).
Plug 10 s preferably made from an open framework 12 of a first highly elastic material covered with a substantially continuous web 14 of a second highly elastic material. For example, framework 12 may be maαe of nitmol metal and web 14 may be made of silicone. An illustrative technique for making plug 10 is to braid 0.002 to 0.003 inch nitinαl wire on a 0.350 inch diameter rod. (The dimensions given herein are only illustrative and will vary depending on the desired size of plug 10.) The resulting nitmol wire mesh is then placed on two forming structures having the shape and approximate relative locations of finished plug discs 30 and 50. These two forming structures are then rotated relative to one another about a central longitudinal axis extending between them to tightly twist the portion of the nitmol wire mesh between them. The wire mesh is then treated (e.g., with heat) to cause it to set m the shape that it has on the forming members (with the tight twist between) . The forming members are then removed and the resulting framework 12 is coated with silicone to produce substantially continuous web 14 on the framework.
In use as shown, for example, in FIG. 2, linking structure 40 pacses through tne hole m the
body tissue wall that is to be plugged. Disc 30 is on one side of that wall, and disc 50 is on the other side of that wall. Linking structure 40 preferably substantially fills the hole to be plugged. The above- mentioned tight twist of linking structure 40 substantially prevents body fluid flow through the linking structure. Discs 30 and 50 hold linking structure 40 in place and cooperate with the linking structure to hold one another in place. Discs 30 and 50 bear resiliently on the opposite sides of the body tissue wall to help prevent body fluid flow around linking structure 40. The entire plug is preferably highly resilient to minimize tissue trauma and to enhance bio-acceptability. Illustrative apparatus 100 for applying a plug like plug 10 is shown in FIG. 3. The following description of apparatus 100 and of illustrative use of that apparatus will also constitute a description of illustrative methods of applying a plug like plug 10. As shown in FIG. 3 illustrative apparatus 100 includes a tubular mandrel 110. Plug 10 is deformed into a substantially tubular shape by placing it on the distal end of mandrel 110. For example, if the diameter of the earlier-mentioned rod on which the framework 12 of plug 10 was initially formed was 0.350 inches, the diameter of mandrel 110 may be about 0.085 inches .
Plug 10 may have several features not previously mentioned that cooperate with mandrel 110 and related apparatus. One of these features may be a closed or substantially closed end 32 shown on the left in FIG. 3. At end 32 the members of framework 12 come together or substantially together, and web 14 may be continuous or substantially continuous over that end. An exception may be made for a small hole or
perforation end 32 if the plug and associated apparatus like 110 are to be inserted via a guidewire (not shown but extremely well known in such procedures as mtravascular catheter therapy) . End 32 remains distal at the distal end of tube 110. Another feature that plug 10 may have is a relatively strong ring or band 52 as part of its framework 12 at the end of the plug remote from end 32. Band 52 may be formed by massing together and fusing strands of framework 12. Band 52 tends to retain its shape (e.g., 0.085 inch diameter) through all deformations of the remainder of plug 10.
Plug 10 is releasably held on the distal end of tuoe 110 by a releasable retainer mechanism 120. In the illustrative embodiment shown in FIG. 3, mechanism 120 is a loop of wire 122 that extends distally through tune 110, then out through an aperture 112 in the side of tur»e 110 proximal of plug 10, and then around band 52. Wire 122 is preferably one continuous length between two ends that are both initially outside the proximal portion of tube 110 and also outside the patient. The distal loop of wire 122 through band 52 exerts a proximally directed force on plug 10 in order to retain the plug on the distal end of tube 110 as shown in FIG. 3.
In the condition shown m FIG. 3 plug 10 may be delivered to the body tissue hole to be plugged via delivery tube 130. For example, if plug 10 is to be applied mtralumenally, tube 130 may extend along the interior of a tubular body organ. The distal end of tube 130 may initially extend a short way through the hole to be plugged. Tube 110 with plug 10 on its distal end as shown m FIG. 3 is moved distally through tube 130 until the distal portion of plug 10 is beyond the distal end of tube 130 and through the nole to be
plugged. Plug 10 is then gradually released from tube 110 by allowing the loop of wire 122 to move distally. This allows plug 10, which is trying to resume the shape shown m FIGS. 1 and 2, to begin to move distally relative to tube 110.
The first part of plug 10 to resume its FIGS. 1 and 2 shape is disc 30. Thus disc 30 forms outside the body organ tube having the hole to be plugged. When disc 30 has re-formed, tubes 130 and 110 can be pulled back to withdraw tube 130 from the hole to be plugged and to help snug disc 30 up aga_nst the outer surface of tne body organ tube wall. Further withdrawal of tubes 130 ana 110 and further slackening of w re 122 allows plug 10 to come completely off tube 110 and to return completely to the shape shown in
FIGS. 1 and 2. In particular, disc 50 re-forms inside the oody organ tube, and linking structure 40 resumes its tightly twisted condition through the hole to be plugged. Plug 10 is now fully installed as shown in FIG. 2 and can be completely released from wire 122 by releasing one end of the wire and pulling the wire out of tne patient starting from the other end. Tubes 11C and 130 can also be withdrawn from the patient.
It should be noted that installation of plug 10 is reversible until the plug is released from wire 122. For example, if after disc 30 has been allowed to re-form, the position of the plug is not satisfactory, wire 122 can be retigntened to pull plug 10 back onto tube 110 as shown in FIG. 3. If desired, plug 10 and/or any of its installation apparatus such as tube 110 and/or tube 130 can be provided with radiologic components to permit radiologic observation of the plug and its installation. Ac just one example, tuoe 110 and/or tube 130 can be provided with radio-opaque bands. As
another example, band 52 on plug 10 can be made radio- opaque. As still another example, as discs 30 and 50 re-form during installation of the plug, those portions of the plug tend to become denser and therefore more radiologically (e.g., fluoroscopically) visible.
Although band 52 is shown and described as remaining open at substantially all times, band 52 could be constructed (e.g., of nitinol) to close down when not stretched around tube 110. Band 52 could be made of plastic or steel. The apparatus shown in FIG. 3 could be deployed along a central guidewire (e.g., through tube 110 and out via an aperture or perforation in end 32) if desired and as has been mentioned earlier. Tube 130 may not be necessary in all cases and can be omitted if not needed.
Intralumenal application of plug 10 has been mentioned above, but the plug 10 can alternatively be applied in other ways such as from the outside of a vessel or other body organ tissue wall requiring a plug. It will be understood that the foregoing is only illustrative of the principles of this invention and that various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. For example, the framework 12 of the plug can be formed in any of many different ways such as by cutting apertures m an initially imperforate structure; forming a mesh of strands of framework material; braiding, knitting, weaving, or felting together strands of f_c_mework material; etc. As has been said, the framework material is preferably an elastic material. Preferred materials are metal, although polymeric materials may also be used. The presently most preferred material is nitinol, and the presently most preferred structure for the framework is a braid of nitinol wires.
The covering 14 on framework 12 is also preferably an elastic, rubber-like material. The covering may be inside the framework, outside the framework, or both inside and outside the framework. The framework is preferably at least partly embedded m the covering. Preferred rubber-like materials for the covering are polymeric materials, especially polymeric rubber materials. Tne presently most preferred rubberlike material is silicone. Examples of other suitable rubber-like materials are stretchable urethane, stretchable PTFE, natural rubber, and the like. For some applications t may be desirable to make the covering porous. Otner applications may not benefit from sucn porosity. Thus the covering can be either porous or non-porous as desired. Illustrative porosities and techniques for producing porosity are described in the above-mentioned Golds.teen et al. reference in the context of artificial graft structures which can have coverings similar to the coverings used on the plugs of this invention.
The plug may include one or more coatings over covering 14. Tne coating (s) may be inside the plug, outside the plug, or both inside and outside the plug. Possible coating materials include bio- compatible materials and/or drugs. Examples include nydrophylic polymers such as hydrophylic polyurethane (to create a lubπcious surface) , parylene (a polymer commonly used to coat pacemakers) , PTFE 'which may be deposited from a PTFE vapor using a process that is sometimes called vapor transport) , tne drug Heparm (a common anti-coagulant), collagen, human cell seeding, etc. One purpose of such a coating may be to give the coated surface a very high degree of bio-compatibility and/or a very high degree of smoothness. Any coatings tnat are used preferably do not interfere with the
elasticity of the plug. The coating (s) may be applieα at any suitable and convenient time during the manufacture of the plug. The coating (s) may be applied using any suitable technique such as dipping, electrostatic spraying, vapor transport, in vitro cell reproduction, etc.
The most preferred plugs of this invention (e.g., those with a framework 12 of braided nitmol wires and a silicone covering 14) are highly elastic. The elastic nature of these plugs allows them to be deployed less invasively (e.g., mtravascularly or at least percutaneousiv; . This may avoid or reduce the need for surgical implantation. For example, a plug of this invention can r>e axially stretched to many times its relaxed length, wnich greatly reduces its diameter. This facilitates mtralumenal delivery of the plug. When released from the delivery appara.tus, the plug automatically returns to its relaxed shape, with no ill-effects of any kind from its previous deformation. In the plugs of this invention that are made with a braided nitmol wire framework 12 and a silicone covering 14, the preferred wire diameter is m the range from about 0.0005 to about 0.01 inches. An especially preferred wire diameter is about 0.002 to about 0.003 inches. Tne preferred silicone covering thic ness is in the range from about 0.00025 to about 0.1 inches .
As another example of modifications within the scope of the invention, the particular shapes shown for the various portions of plug 10 are only illustrative and can be varied if desired. Instead of being round discs, plug portions 30 and/or 50 could be elliptical, polygonal, ovoid, or of any other suitable shape. The particular plug dimensions mentioned herein are also only illustrative, and it will be appreciateα
that the plugs cf this invention can be made in a wide range of sizes for a variety of medical applications.