Patent Application
20060173472
The invention relates to medical devices and methods, and in particular, to devices for the treatment of obesity.
Various surgical techniques have been developed to treat morbid obesity. One of these techniques involves use of a gastric banding device. Conventional hydraulic gastric bands are typically constructed in the form of a hollow tube fabricated from an elastomer, such as silicone rubber. The band can be inserted through a laproscopic cannula to completely encircle the upper end of the stomach and thus restrict the passage of food into the lower stomach. Saline is injected or withdrawn from the band by inserting a needle into an injection port placed just under the patient's skin. The degree of gastric constriction provided by the band, which affects the amount of food the patient can ingest, can be adjusted by varying the amount of saline in the band.
These conventional hydraulic gastric banding devices exert a continuous restricting force on the stomach to reduce the size of the upper stomach and to restrict the passage of food from the upper to the lower stomach. However, because saline passively diffuses through the walls of the elastomer, hydraulic bands do not offer stable banding over time. Additional medical procedures may therefore be necessary to refill the band to maintain its optimal configuration, increasing the cost and the number of medical visits. Also, each time the band is refilled, the patient's skin must be punctured, resulting in discomfort for the patient and an increased risk of infection.
In general, the invention is directed to a gastric banding device containing an expandable material. The expandable material may include, for example, a hydrogel material that expands when hydrated. The hydrogel material may include a single or multiple monolithic components, and/or may include hydrogel material in particulate form, such as hydrogel beads, microspheres, or powder. The gastric banding device includes an elongate gastric band having an expandable lumen that forms a stoma opening in the stomach by encircling and partitioning the stomach into an upper stomach and a lower stomach. A hydrogel material is positioned in the lumen and expands when hydrated to at least partially expand the lumen, thus decreasing the size of the stoma opening. After a period of time, the hydrogel material reaches equilibrium. Because hydrogel materials are very stable at equilibrium, the problem of fluid leakage experienced by conventional gastric banding systems is reduced and the geometric configuration of the band may be maintained for long periods of time. The band may also be used with other portions of the gastrointestinal (GI) tract, such as the esophagus, intestines, etc.
In one embodiment, the invention is directed to a device comprising an elongate gastric band having a radially expandable lumen that forms a stoma opening in the stomach by encircling and partitioning a stomach into an upper stomach and a lower stomach, and a hydrogel material positioned in the lumen that expands when hydrated to at least partially expand the lumen.
In another embodiment, the invention is directed to a device comprising a gastric occluding device positioned to restrict ingestion of food by a patient and having at least one expandable lumen, and an expandable material positioned within the lumen that expands when hydrated to at least partially expand the lumen.
In another embodiment, the invention is directed to method comprising implanting a gastric band having at least one expandable lumen with material that expands when hydrated positioned therein such that the gastric band forms a stoma opening in the stomach of a patient by encircling and partitioning a stomach into an upper stomach and a lower stomach, and injecting fluid into the expandable lumen to at least partially hydrate the material and to decrease the stoma opening.
In another embodiment, the invention is directed to a method comprising implanting a gastric band having at least one expandable lumen filled with a fully hydrated hydrogel material such that the gastric band forms a stoma opening in the stomach of a patient by encircling and partitioning a stomach into an upper stomach and a lower stomach.
In another embodiment, the invention is directed to a method comprising implanting a gastric band having at least one expandable lumen such that the gastric band forms a stoma opening in the stomach of a patient by encircling and partitioning a stomach into an upper stomach and a lower stomach, and injecting a slurry of particulate hydrogel material into the expandable lumen to at least partially expand the lumen and decrease the stoma opening.
In another embodiment, the invention is directed to a device comprising an elongate gastric band having a radially expandable lumen that forms a stoma opening in the stomach by encircling and partitioning a stomach into an upper stomach and a lower stomach, and an injection port in fluid connection with the lumen to receive and deliver a slurry of particulate hydrogel material into the expandable lumen to at least partially expand the lumen and decrease the stoma opening.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
Hydrogels are networked structures of polymer chains that are crosslinked to each other. In the presence of an aqueous solution, such as water, saline, body fluids, etc., the polymer chains absorb water and swell. Hydrogels can therefore assume a dehydrated state, a partially hydrated state, and a fully hydrated, or equilibrium, state. A hydrogel material in its dehydrated state is generally substantially smaller than the material in its hydrated state. Examples of hydrogel materials which may be used are the polyacrylonitrile copolymers as described in U.S. Pat. Nos. 4,943,618 and 5,252,692, which are incorporated herein by reference. Other types of hydrogel materials may include a co-polymer of polyacrylonitrile and polyacrylamide. Other hydrogel materials, however, could also be used. The hydrogel materials can be crosslinked or non-crosslinked, they can belong to the class of homopolymers or copolymers or the blends of these materials with each other. Other examples of synthetic hydrophilic polymers that can be used include, but are not limited to, polyacrylic acid, polymethacrilic acid, polyacrylaamid, polyhydroxyethylmethacrylate, polyhydroxyetrhyl methacrylate, polyvinylalcohol, polyethylene oxide, polyvinylpyrrolidone, polyuerethane, polysiloxanes, or poluethylenimines.
By controlling relative amounts of copolymers, it may be possible to regulate physical qualities of the hydrogel such as flexibility of the hydrogel material at equilibrium, the degree of swelling, and/or the rate of swelling. Depending upon the composition of hydrogel material 24 and the amount of fluid, it may take hydrogel material 24 from a few minutes to a few hours to expand and reach equilibrium. Depending upon its composition, hydrogel material 24 may absorb an amount of fluid such that its weight percent of water in the equilibrium state is anywhere between approximately 10% and 99%. The hydrogel will swell as a function of the amount of water absorbed and the composition of the hydrogel material. The physical properties of the hydrogel material may be chosen based on, among other things, the needs of each specific patient and the desired size of the stoma opening.
Hydrogel material 24 may include a single or multiple monolithic components, and/or may include hydrogel material in particulate form, such as hydrogel beads, microspheres, or powder.
In one embodiment, hydrogel material 24 is fully hydrated within lumen 17 before the band 12 is implanted within the patient. In this embodiment, the physician ses the band as it will be once implanted in the patient. In another embodiment, hydrogel material 24 is positioned within lumen 17 in a dehydrated or partially hydrated state at the time of implantation. Fluid is delivered to lumen 17 after implantation to at least partially hydrate the hydrogel material, causing the band 12 to expand and decrease the size of the stoma opening. In another embodiment, a slurry of fluid and particulate hydrogel material is delivered to the lumen within the band 12 via an injection port. Once inside band 12, the particulate hydrogel material absorbs the fluid and swells, causing the band 12 to expand and decrease the size of the stoma opening. In any embodiment, additional fluid may be delivered to further hydrate/expand band 12 and thus adjust the size of the stoma opening. In another embodiment, after band 12 is placed and secured around the stomach, water will diffuse through the elastomer tube and be absorbed by hydrogel material 24, causing the band to swell, and the inside diameter 21 of the band to decrease.
To implant band 12 within a patient, a physician positions band 12 around the stomach 8 until the desired diameter of band 12 is reached (see
In the example shown in
In embodiments where some or all of hydrogel material 24 is in particulate form, hydrogel could be removed from the device via injection port 20 using a syringe and needle if it were determined that band 12 is too tight and that the stoma opening is too small. Residual water not absorbed by hydrogel material 24 may also be removed. Conversely, band 12 may be tightened by adding additional particulate hydrogel (in either the hydrated or dehydrated form) to the band via injection port 20.
In either of the embodiments shown in FIGS. 7 or 8, or in other embodiments described herein, the size of the stoma opening may be adjusted at any time by delivering additional fluid to further hydrate/expand band 12. Similarly, in some embodiments, after band 12 is placed and secured around the stomach, water will diffuse through the elastomer tube and be absorbed by hydrogel material 24, causing the band to swell, and the inside diameter of the band to decrease. The stoma opening may also be adjusted by removing residual fluid or particulate hydrogel material via injection port 20.
The preceding specific embodiments are illustrative of the practice of the invention. It is to be understood, therefore, that other expedients known to those skilled in the art or disclosed herein may be employed without departing from the invention or the scope of the appended claims. For example, the invention is not limited to the particular shapes of expandable elements depicted in the figures. For example, although some of the expandable elements described herein have substantially circular perimeters, and the perimeters expand as the expandable elements assume the hydrated state, it shall be understood that in other embodiments, the perimeters of the expandable elements can take on different shapes, such as substantially elliptical or triangular, for example. In addition, the invention encompasses embodiments in which the expandable elements expand further in one direction than in another. The invention also encompasses embodiments in which one or more expandable element is folded or rolled to reduce its profile in the dehydrated state. As such an expandable element expands, the expandable element automatically unfolds or unrolls.
The preceding specific embodiments are illustrative of the practice of the invention. It is to be understood, therefore, that other embodiments known to those skilled in the art or disclosed herein may be employed without departing from the invention or the scope of the claims. For example, the present invention further includes within its scope methods of making and using systems as described herein.
Many embodiments of the invention have been described. Various modifications may be made without departing from the scope of the claims. These and other embodiments are within the scope of the following claims.
