ARAD, Michael (32 Remez Street, Tel Aviv, 62192, IL)
ARAD, Michael (32 Remez Street, Tel Aviv, 62192, IL)
| CLAIMS We claim: 1. A system for decreasing the gastric volume of a subject, said system comprising: an inflatable sleeve sized such that when inserted into the stomach of a subject, it extends over at least a part of the length of the stomach between the esophagus and the pylorus; at least one protuberant element attached to said inflatable sleeve and positioned such that when deployed, it extends from said inflatable sleeve into the gastric body; and ablation elements associated with said at least one protuberant element, and disposed facing the anterior and posterior walls of said stomach, such that when activated, said elements ablate areas of the gastric wall facing said at least one element, without ablating areas of said gastric wall facing said sleeve when inflated. 2. A system according to claim 1 and wherein said inflatable sleeve is adapted to lie close to the lesser curvature of said stomach, and said at least one protuberant element is positioned to extend in a direction away from the lesser curvature of the stomach. 3. A system according to claim 1 and wherein said inflatable sleeve is adapted to lie within the stomach body, and said at least one protuberant element is at least two protuberant elements positioned on both sides of said inflatable sleeve. 4. A system according to any of the previous claims and further comprising a gastric suction source adapted for application to the subject, such that application of said suction causes said anterior and posterior walls of said stomach to juxtapose said at least one protuberant element. 5. A system according to any of the previous claims and wherein said ablation elements utilize energy in the form of any one of microwave energy, radio frequency energy, laser energy and water jet energy. 6. A system according to any of claims 1 to 4 and wherein said ablation elements utilize cryo-ablation. 7. A system according to any of claims 1 to 4 and wherein said ablation elements utilize the effect of drugs or chemicals to generate said ablation. 8. A system according to any of the previous claims, and wherein said ablation elements generate damage to any layer of gastric wall facing said elements including, but not limited to the muscularis externa. 9. A system according to any of the previous claims, wherein said ablation elements comprise electrodes and wherein application of a radio frequency current of predetermined level to said electrodes ablates areas of the gastric wall facing said electrodes, without ablating areas of said gastric wall facing said sleeve. 10. A system according to claim 9 wherein said electrodes are disposed on the surface of said at least one protuberant element. 11. A system according to claim 9 wherein said electrodes are needles attached to the surface of said at least one protuberant element. 12. A system according to any of the previous claims, wherein said at least one protuberant element extends the full length of the stomach between the esophagus and the pylorus. 13. A system according to any of claims 1 to 11 , wherein said at least one protuberant element extends along only part of the length of the stomach, said system further comprising a mechanism for moving said at least one protuberant element along the full length of the stomach. 14. A system according to any of the previous claims and wherein said at least one protuberant element is an inflatable balloon structure attached to said inflatable sleeve. 15. A system according to claim 14, wherein said inflatable balloon structure is inflated either by means of passages connecting it to said inflatable sleeve, or by means of a separate inflation tube. 16. A system according to any of claims 1 to 13 and wherein said at least one protuberant element is a deployable mechanical structure. 17. A system according to claim 16, wherein said deployable mechanical structure comprises a hinged element which is deployed by rotation of said structure around said hinge after said system has been inserted into the subject's stomach. 18. A method for decreasing the gastric volume of a subject, said method comprising: inserting an inflatable sleeve into the stomach of a subject, said inflatable sleeve having attached thereto at least one protuberant element having associated therewith ablation elements disposed facing the anterior and posterior walls of said stomach; inflating said inflatable sleeve and positioning it such that it extends over at least a part of the length of the stomach between the esophagus and the pylorus; deploying said at least one protuberant element such that it extends from said inflatable sleeve into the gastric body; and activating said ablation elements such that they ablate areas of the gastric wall facing said ablation element, without ablating areas of said gastric wall facing said inflated sleeve. 19. A method according to claim 18 further comprising the step of positioning said inflatable sleeve to lie close to the lesser curvature of said stomach, said at least one protuberant element being attached to said inflatable sleeve such that it extends in a direction away from the lesser curvature of the stomach. 20. A method according to claim 18 further comprising the step of positioning said inflatable sleeve to lie within the stomach body, said at least one protuberant element being at least two protuberant elements attached to said inflatable sleeve such that they are positioned on both sides of said inflatable sleeve. 21. A method according to any of claims 18 to 20 and further comprising the step of applying gastric suction to the subject, such that said anterior and posterior walls of said stomach juxtapose said at least one protuberant element. 22. A method according to any of claims 18 to 21 wherein said step of activating said ablation elements comprises the application of energy in the form of any one of microwave energy, radio frequency energy, laser energy and water jet energy. 23. A method according to any of claims 18 to 21 and wherein said ablation elements utilize cryo-ablation. 24. A method according to any of claims 18 to 21 and wherein said ablation elements utilize the effect of drugs or chemicals to generate said ablation. 25. A method according to any of claims 18 to 24, and wherein said ablation elements are activated sufficiently to generate damage to any layer of gastric wall facing said element, including, but not limited to the muscularis externa. 26. A method according to any of claims 18 to 25, wherein said ablation elements comprise electrodes, and wherein application of a radio frequency current of predetermined level to said electrodes ablates areas of the gastric wall facing said electrodes, without ablating areas of said gastric wall facing said sleeve. 27. A method according to claim 26 wherein said electrodes are disposed on the surface of said at least one protuberant element. 28. A method according to claim 26 wherein said electrodes are needles attached to the surface of said at least one protuberant element. 29. A method according to any of claims 18 to 28, wherein said at least one protuberant element is such as to extend the full length of the stomach between the esophagus and the pylorus. 30. A method according to any of claims 18 to 28, wherein said at least one protuberant element is such to extend along only part of the length of the stomach, said method further comprising the step of moving said at least one protuberant element along the full length of the stomach. 31. A method according to any of claims 18 to 30 and wherein said at least one protuberant element is an inflatable balloon structure attached to said inflatable sleeve. 32. A method according to claim 31 , further comprising the step of inflating said inflatable balloon structure either by means of passages connecting it to said inflatable sleeve, or by means of a separate inflation tube. 33. A method according to any of claims 18 to 30 and wherein said at least one protuberant element is a deployable mechanical structure. 34. A method according to claim 33, wherein said deployable mechanical structure comprises a hinged element, said method further comprising the step of deploying said mechanical structure by rotation thereof around said hinge after said system has been inserted into the subject's stomach. |
FIELD OF THE INVENTION
The present invention relates to the field of the treatment of obesity, especially by the use of an endoscopic gastric ablation procedure.
BACKGROUND OF THE INVENTION
Obesity represents a significant burden on society. In the USA, it is estimated that approximately $100 Billion are spent each year in direct costs for the treatment of obesity and in indirect costs for the significant side effects of obesity on the cardiovascular system, skeletal system, and other anatomical systems, and the resulting hospitalizations, treatments and loss of work days.
Surgical treatment of morbid obesity generally falls into one of two groups - restrictive operations where part of the Gl tract is restricted, thus limiting the quantity of food that the subject can ingest, and malabsorptive treatments where absorption of calories from the ingested food is limited by surgical intervention of the Gl tract. A current common surgical treatment of the first group is based on a constricting device that is placed around the proximal part of the stomach in order to restrict the quantity of food ingested during each meal and to achieve a sensation of satiety. Such a device, known commercially as the Lap-Band® was first described in the article by Dr. Solhaug, entitled "Gastric Banding, A New Method in the Treatment of Morbid Obesity" published in Current Surgery, pp.424-428, Nov.-Dec, 1983, and aspects thereof were shown thereafter in U.S. Patent No. 4,696,288.
The malabsorptive type of treatment includes various kinds of bypass operations, such as the duodenal switch, in which a large part of the small intestine is bypassed, such that the food ingested enters only a short remaining length of the small intestine, resulting in significantly reduced absorption. In the Roux-en-Y gastric bypass operation, the proximal end of the stomach is divided creating a small proximal pouch. The jejunum is divided about 1 ft distal to the duodenum. The distal part of this resection is anastomosed to the proximal pouch and the proximal part is anastomosed to the small intestine about 3-5 ft below the stomach. This is thus both a restrictive and a malabsorptive type of procedure.
A further common procedure is sleeve gastrectomy in which most of the stomach is resected by stapling along the lesser curvature, creating a reduced volume sleeve in place of the complete stomach. Though this is primarily a restrictive type of operation, it is believed that there may also be a malabsorptive element involved. Additionally, there seems to be a physiological effect of reduced appetite, possibly related to the grehlin inhibition generated as a result of the procedure.
There is a trend to perform those of the above procedures where it is feasible, using laparoscopic techniques, which incurs faster convalescence. Despite the advancements in laparoscopy, these operations are demanding, especially in the morbidly obese patients and are accompanied by a significant percent of side effects and complications, due to either or both of the surgery itself, and the general anesthesia which has significant risks for such patients.
Endoscopic restrictive procedures exist for partitioning the stomach from within, to reduce the effective stomach size, such as by stapling along its length. The high level of activity present in the stomach, both bio-mechanical, physiological and biochemical, may make such procedures problematic.
In US Patent No. 6,427,089 for "Stomach Treatment Apparatus and Method" to E.W. Knowlton, there is described apparatus for applying microwave energy by means of a moveable application member, to sequentially selected parts of the stomach wall to produce lesions and/or tissue contraction within the stomach wall while preserving the mucosal layer, such that gastric dispensibility is reduced. The apparatus uses fluid cooling to prevent damage to the mucosal layer, and it appears that the main effect is that of the changed nature of the muscularis externa, whose flexibility and ability to distend is reduced by the procedure.
In US Patent No. 6,325,798 for "Vacuum Assisted Systems and Methods for Treating Sphincters and Adjoining Tissue Regions" to S. Edwards et al, there is described the deployment of an electrode carrier for RF treatment of the lower esophogeal sphincter region to reduce GERD. The electrode is in the form of needles such that it penetrates the mucosa, and generates thermal lesions in the submucosa. The carrier is moved to cover the sphincter region to be treated.
These methods require careful positioning of the electrodes at the appropriate treatment position, so as not to cause damage to tissues which it is not intended to treat, and their efficacy may not be optimal for large scale treatment of the subject's stomach.
There therefore exists a need for an improved device and method for a restrictive treatment for the prevention of obesity, which overcomes at least some of the disadvantages of prior art methods and devices.
The disclosures of each of the publications mentioned in this section and in other sections of the specification are hereby incorporated by reference, each in its entirety.
SUMMARY OF THE INVENTION
The present invention seeks to provide a new device and method for controlling obesity in patients by the performance of an endoscopic procedure which simulates the effects of sleeve gastrectomy, but without the need to apply staples to the stomach wall. The procedure may also be termed "virtual sleeve gastrectomy". Ablation is applied to part of the stomach wall, to create a reduction in gastric volume. Unlike the prior art gastric ablation methods mentioned hereinabove, by using the present device and methods, no attempt is made to keep the mucosa at the treated region intact, and the ablated region of the stomach is no longer meant to be functional after the treatment. The ablation procedure is performed endoscopically, such that it should be well tolerated and generally less traumatic than many of the prior art methods.
One exemplary method by which this can be achieved utilizes an inert sleeve, preferably in the form of a balloon, which is inserted endoscopically in an uninflated form through the esophagus into the gastric volume, and is positioned such that it traverses the full length of the stomach up to the pylorus. Once correctly located, the sleeve balloon is inflated, such that it forms a cylindrical sleeve, preferably maneuvered to lie along the lesser curvature wall of the stomach, and preferably in contact with it. The sleeve has at least one deployable protuberance associated therewith, which may also conveniently be in the form of a balloon, though mechanically deployable protuberances are also feasible. The protuberant element extends from the sleeve through the body of the stomach towards the greater curvature wall of the stomach wall. The protrusion should optimally be deployed only when the sleeve is in its predetermined position. On this protrusion, there are located ablation elements, which could be electrodes, which can be supplied with microwave or radio frequency (RF hereinafter) ablation current, or which can utilize any other suitable ablation process, such as cryo-ablation, drugs or chemical action, laser ablation, water jet ablation, or the like. Since RF energy is a particularly convenient and readily controllable ablation source, the main implementations of the devices and methods of this application will be described in terms of RF ablation, though it is to be understood that the devices and methods are not intended to be limited thereto. The RF current is adjusted to ablate the stomach wall in proximity to the electrodes, creating thermal lesions of the mucosa, and at least down to the submucosa. The RF power has to be carefully selected to ensure that the ablation process does not cause penetration of the stomach wall. The electrodes are preferably in the form of adjacent pairs, with the RF current applied between each electrode of a pair. Alternatively and preferably, the electrodes can be in the form of needles which penetrate the surface of the gastric wall.
In order to bring the stomach wall into proximity or even contact with the electrodes on the ablation element or elements, a vacuum may be applied through the esophagus, either using the endoscope suction or a separate channel, pulling the stomach wall into contact with the sleeve and the ablation protrusion. The sleeve in close contact with the stomach wall protects the region of the lesser curvature of the stomach from stray RF currents, such that no ablation of the stomach wall should occur along the sleeve surface.
On completion of the ablation process, after a predetermined treatment time or when thermal monitoring of the tissue indicates that the treatment should be complete, the protrusion balloon and the sleeve balloon are then deflated and removed, and the result is a sleeve shaped gastric region without any impairment of the gastric functions, because of the protection of the inflated sleeve, while the inner tissues of that portion of the stomach wall which underwent ablation are so damaged that they undergo gradual necrosis, and shrink substantially from the ensuing fibrosis. If the correct ablation conditions have been applied, the remaining gastric wall tissue, mainly the muscularis externa, shrinks down upon itself, thus essentially eliminating the gastric volume outside of the unablated sleeve-like gastric pouch.
According to various exemplary implementations, systems for decreasing the gastric volume of a subject described in this disclosure, may comprise:
(i) an inflatable sleeve sized such that when inserted into the stomach of a subject, it extends over at least a part of the length of the stomach between the esophagus and the pylorus,
(ii) at least one protuberant element attached to the inflatable sleeve and positioned such that when deployed, it extends from the inflatable sleeve into the gastric body, and
(iii) ablation elements associated with the at least one protuberant element, and disposed facing the anterior and posterior walls of the stomach, such that when activated, the elements ablate areas of the gastric wall facing the at least one element, without ablating areas of the gastric wall facing the sleeve when inflated.
In such systems, the inflatable sleeve may be adapted to lie close to the lesser curvature of the stomach, and the at least one protuberant element is then positioned to extend in a direction away from the lesser curvature of the stomach. Alternatively, the inflatable sleeve may be adapted to lie within the stomach body, and the at least one protuberant element is then at least two protuberant elements positioned on both sides of the inflatable sleeve.
Any of such systems may further comprise a gastric suction source adapted for application to the subject, such that application of the suction causes the anterior and posterior walls of the stomach to juxtapose the at least one protuberant element.
Furthermore, in any of the above-described systems, the ablation elements may utilize energy in the form of any one of microwave energy, radio frequency energy, laser energy or water jet energy, or they may use cryo- ablation or the effect of drugs or chemicals to generate the ablation. In any of these implementations the ablation elements may generate damage to any layer of gastric wall facing the elements including, but not limited to the muscularis externa.
Furthermore, in any of the above described systems, the ablation elements may comprise electrodes, and application of a radio frequency current of predetermined level to the electrodes ablates areas of the gastric wall facing the electrodes, without ablating areas of the gastric wall facing the sleeve. Such electrodes may be either disposed on the surface of the at least one protuberant element, or they may be in the form of needles attached to the surface of the at least one protuberant element.
The at least one protuberant element in the above described implementations may extend either the full length of the stomach between the esophagus and the pylorus, or may extend along only part of the length of the stomach, the system further comprising a mechanism for moving the at least one protuberant element along the full length of the stomach.
Additionally, the at least one protuberant element may advantageously be an inflatable balloon structure attached to the inflatable sleeve, in which case the inflatable balloon structure may be inflated either by means of passages connecting it to the inflatable sleeve, or by means of a separate inflation tube. Alternatively, the at least one protuberant element may be a deployable mechanical structure, in which case it may comprise a hinged element which is deployed by rotation of the structure around the hinge after the system has been inserted into the subject's stomach.
Yet other implementations described in this disclosure may involve a method for decreasing the gastric volume of a subject, the method comprising:
(i) inserting an inflatable sleeve into the stomach of a subject, the inflatable sleeve having attached thereto at least one protuberant element having associated therewith ablation elements disposed facing the anterior and posterior walls of the stomach,
(ii) inflating the inflatable sleeve and positioning it such that it extends over at least a part of the length of the stomach between the esophagus and the pylorus,
(iii) deploying the at least one protuberant element such that it extends from the inflatable sleeve into the gastric body, and (iv) activating the ablation elements such that they ablate areas of the gastric wall facing the ablation element, without ablating areas of the gastric wall facing the inflated sleeve.
In such a method, the inflatable sleeve may be positioned to lie close to the lesser curvature of the stomach, and the at least one protuberant element is then positioned to extend in a direction away from the lesser curvature of the stomach. Alternatively, the inflatable sleeve may be adapted to lie within the stomach body, and the at least one protuberant element is then at least two protuberant elements positioned on both sides of the inflatable sleeve.
The method may also comprise the step of applying gastric suction to the subject, such that the anterior and posterior walls of the stomach juxtapose the at least one protuberant element.
Furthermore, in any of the above-described methods, the step of activating the ablation elements may comprise the application of energy in the form of any one of microwave energy, radio frequency energy, laser energy and water jet energy. The ablation elements may alternatively use cryo-ablation or the effect of drugs or chemicals to generate the ablation.
In any of these implementations the ablation elements may be activated to generate damage to any layer of gastric wall facing the elements including, but not limited to the muscularis externa.
Furthermore, in any of the above described methods, the ablation elements may comprise electrodes, and application of a radio frequency current of predetermined level to the electrodes ablates areas of the gastric wall facing the electrodes, without ablating areas of the gastric wall facing the sleeve. Such electrodes may be either disposed on the surface of the at least one protuberant element, or they may be in the form of needles attached to the surface of the at least one protuberant element.
The at least one protuberant element in the above described methods may extend either the full length of the stomach between the esophagus and the pylorus, or may extend along only part of the length of the stomach, in which case the method then further comprises moving the at least one protuberant element along the full length of the stomach.
Additionally, in any of the above described methods, the at least one protuberant element may advantageously be an inflatable balloon structure attached to the inflatable sleeve, in which case the inflatable balloon structure may be inflated either by means of passages connecting it to the inflatable sleeve, or by means of a separate inflation tube. Alternatively, the at least one protuberant element may be a deployable mechanical structure, in which case it may comprise a hinged element which is deployed by rotation of the structure around the hinge after the system has been inserted into the subject's stomach.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:
Fig.1 shows a sectional schematic view of the stomach, with an ablation sleeve of the present invention inserted;
Fig. 2 shows schematically the sleeve after the balloon section has been inflated;
Fig. 3A is a schematic cross section of the stomach, showing the inflated ablation sleeve, and the deployed protuberant balloon; Fig. 3B is an alternative preferred embodiment of the sleeve balloon, having a central passage;
Fig. 4 shows is an anterior sectional view of the stomach, showing a deployed full height protuberant balloon with its ablation electrodes;
Figs. 5A to 5C are views similar to that of Fig. 4, but showing embodiments using partial height protuberant balloons with ablation electrodes;
Figs. 6A to 6C show schematically a mechanically deployed ablation electrode arrangement;
Fig. 7 shows schematically the stomach wall sucked into close contact with the protuberance balloon after application of a vacuum;
Fig. 8 shows schematically the ultimately obtained substantially reduced gastric volume as a result of the treatment with the apparatus of the present invention; and
Fig. 9 shows schematically shows a system with a sleeve positioned for generating a pouch close to the median line of the stomach. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Reference is now made to Fig. 1 , which illustrates schematically a cross- sectional A-P view of the stomach 10, with an ablation sleeve 11 constructed in accordance with a preferred embodiment of the present invention, inserted endoscopically in an uninflated state into the gastric volume, and preferably extending from the esophagus to the pyloric region. The ablation sleeve is sealed at its distal end 12 in order to enable the balloon section of the sleeve to inflate. The balloon section is shown in Fig. 1 by the cross-hatched shading. The sleeve is preferably constrained by its path from the esophagus to the duodenal entrance, to lie close to or in contact with the lesser curvature wall 13 of the stomach. This may be readily achieved such as by affixing the distal end 12 of the sleeve in the vicinity of the duodenal entrance, and by applying slight tension to the neck of the sleeve, such that it conforms to the lesser curvature wall 13 of the stomach.
To commence the treatment, the sleeve is expanded. Fig. 2 shows the sleeve after the balloon section 20 has been inflated by applying external pressure from the outside through the inflation tube 15. The level of inflation is predetermined to define the gastric volume desired at the conclusion of the ablation process - the more the inflation level, the larger the resulting gastric volume. On the side of the balloon sleeve directed away from the lesser curvature, i.e. towards the main volume of the body of the stomach, there is attached a collapsed protuberant element 22, preferably in the form of another uninflated balloon. This protuberant element is inflated once the sleeve 20 is in its correct inflated state. Inflation can be achieved either by means of a separate pressure tube attached to the proximal end of the protuberance 22, or by means of one or more small passages connecting the protuberance balloon to the main balloon, such that the protuberance balloon inflates according to a delayed timescale compared to the inflation of the sleeve balloon, and only completes inflation after the sleeve balloon has fully inflated to its desired size.
Fig. 3A is a schematic cross section of the stomach, shown at the position marked A-A in Fig. 2A, showing the inflated ablation sleeve 22 within the stomach 10, lying along the lesser curvature wall 13. The protuberance balloon 22 is shown after having been inflated, in the embodiment shown in Fig. 3A, by means of a fluid connecting hole 30 between the sleeve balloon and the protuberance balloon. However, a separate inflation tube for the protuberant balloon could equally well be used, and may be even advantageous because of the added flexibility in inflating the two balloons separately, such as when positioning the balloons in the stomach. The protuberant balloon preferably has metallic electrodes 32 applied to its surfaces facing the posterior and anterior walls of the stomach. The ablation electrodes can preferably be flexible metallic layers applied to the protuberant balloon section, or a grid of wires, or any other suitable implementation. The electrodes are activated by application of RF ablation current, preferably fed through leads 33 running through or on the sleeve balloon, and through the endoscopic lumen from the outside.
Reference is now made to Fig. 3B, which is a schematic cross section of an alternative preferred sleeve balloon 35 having an annular form to allow the endoscope to pass through its central channel 36 to provide distal vision, if desired. The bottom of the annulus is, of course, sealed to enable the balloon to inflate correctly.
Reference is now made to Fig. 4 which is an anterior sectional view of the stomach, similar to that of Fig. 2, but showing the protuberant balloon 22 deployed such that its preferred location within the height of the stomach body can be shown. The electrodes 32 are shown covering essentially the whole of the side surfaces of the protuberance balloon, such that they are exposed to the entire anterior and posterior walls of the stomach, other than the region occupied by the inflated sleeve balloon 20. The electrodes preferably have individual leads, such that they can each be activated independently. The use of a flexible balloon to carry the ablation electrodes is especially advantageous since the balloon will generally expand to fill the available volume of the stomach regardless of the shape of that remaining profile.
Alternatively and preferably, instead of the full height protuberant balloon shown in Fig. 4, a protuberant element of limited height can be used. Figs. 5A and 5B show two preferred embodiments by which this can be achieved, both using a protuberant balloon which covers only a portion of the stomach height, and preferably, with only a single pair of electrodes 32 or a small number of electrode pairs on each side. The reduced height elements can be moved from one end of the stomach to the other, from the fundus through the body to the antrum, or the other way around. In Fig. 5A, the protuberant balloon 50 is moved by means of a collar 51 sliding on the sleeve. The motion can be imparted from the outside by means of a wire 52 threaded through the endoscope lumen, or by any other suitable means, as is known in the art. By this means, the electrode structure and electrical connections are simpler to implement, though the need to move the protuberance may add additional complexity to the system. In particular, it may also be necessary to relieve the suction somewhat in order to enable the protuberant element to move, and then to apply it again to regain contact between the electrodes and the gastric wall for the actual ablation, this process being repeated while covering the whole of the stomach height. As the width of the stomach wall region to be ablated varies along the length of the stomach, the protuberant balloon section is allowed to inflate to a longer length or to a lesser length as the device moves along the stomach, to accommodate the required ablation region. The electrodes may be printed or affixed to the fullest extent of the protuberant balloon 53, such that they are always operative even up to the greater curvature wall at the widest point of the stomach.
In the alternative preferred embodiment of Fig. 5B, the sleeve balloon itself 54 has a reduced length, such that it covers only a part of the inner wall of the stomach in the region of the lesser curvature wall. The protuberant balloon 55, like that of Fig. 5A, extends over only a portion of the stomach height, and preferably has only a single pair of electrodes 32 on each side. The protuberant balloon 55 can be fluidly connected to the sleeve balloon, and even constructed as a single inflatable balloon, such that both parts are inflated essentially together. In use, the combination is simply moved from one end of the stomach to the other, preferably by pulling the entire assembly by means of the inflation tube within the endoscope lumen, from the bottom to the top, thus significantly simplifying the motion mechanism. The ablation effect is then performed sequentially over the whole of the desired region of the stomach walls using a sweeping effect, and preferably relaxing the suction during motion.
Since the effect of the RF ablation is generally limited to the wall immediately in the vicinity of the electrodes, the limited length of the sleeve balloon is sufficient to protect those parts of the lesser curvature side gastric wall 57 close to the ablation electrodes, while those areas further away from the location of the electrodes do not need protection. It is necessary to constrain the motion of the sleeve to lie close to the lesser curvature wall in order to maintain the desired channel of unablated gastric wall, whose outer limit is shown by the dashed line 58 in Fig. 5B. The suction applied to the stomach, as described in detail in connection with Fig. 7 below, causes the stomach wall to close in, not only around the protuberant part of the balloon, but also around the sleeve. This effect, together with the effect of the profile of the lesser curvature in relation to the point from which the sleeve is being pulled at the esophogeal entry 59 to the stomach, and together with the effect of the inflation of the protuberant balloon causing it to extend to its fullest extent, combine to ensure that the sleeve does indeed move in close contact to the lesser curvature wall, thus ensuring the integrity of a protected channel along the lesser curvature over the full length of the stomach.
Reference is now made to Fig. 5C, which illustrates schematically yet another method of moving a partial height protuberant balloon along the length of the stomach close to the lesser curvature. The sleeve balloon 44, similar to that shown in Fig. 5B, can be attached preferably by ring structures 46, to a wire or a catheter 45 stretched between the pylorus and the esophagus, much like a curtain is attached to a curtain rail, such that as the sleeve assembly moves up the stomach, it is constrained to move close to the path of the wire stretched along the lesser curvature wall. An anchoring device should preferably be provided to hold the guide wire at the pylorus end of the stomach.
As another alternative preferred embodiment, the protuberance can be a deployable mechanical structure, either in the form of a spring loaded umbrellalike structure, or made of an alloy such as nitinol. Whichever structure is used, it must be capable of being restowed after use, such that the structure can be withdrawn again from the stomach. Figs. 6A to 6C show schematically one preferred embodiment of such a mechanical embodiment, in its stages of deployment, though other preferred arrangements are known in the art. In Fig. 6A, there is shown the housing 60 of the deployable mechanical structure 61 carrying a pair of ablation electrodes 32, connected by leads 62 to the ablation power supply. The deployable mechanical structure 61 is preferably hinged about a pivot pin 63, and is inserted down the esophagus in the stowed position shown. Deployment of the deployable mechanical structure 61 from its housing after insertion into the stomach is preferably actuated either by a spring mechanism 64, or by means of a pull wire 65. Fig. 6B shows the deployable mechanical structure 61 partially deployed, and Fig. 6C shows it fully deployed, and ready for motion along the length of the stomach to ablate the desired walls. The entire mechanism must be mounted within the inflatable sleeve balloon, and a method used, such as a bellows, to enable the deployable mechanical structure 61 to project from the sleeve without the sleeve losing its inflation fluid. The mechanical structure can preferably be made re-stowable by providing it with a stowage cage 68, shown in Figs. 6A to 6C with a dashed outline. The cage has a slot on one side to allow the structure to deploy sideways. Pulling the cage upwards mechanically enables release of the structure to execute the ablation procedure, and pushing it back down, or pulling the structure up enables the structure to be re-stowed for extraction from the stomach. Another mechanical implementation of the present invention could be the use of a mechanically collapsible sleeve can be used to protect the stomach wall in the region where the pouch is to be generated.
Once the protuberant element, of whichever type is used, has been deployed in position, suction is applied to the subject's esophagus preferably using the endoscope suction or by attaching external vacuum to a designated channel. This stage is shown in Fig. 7. The vacuum causes the stomach wall 10 to close in onto the protuberant balloon 22, such that the stomach wall comes into contact with or into close proximity to the electrodes 32 on the wall of the protuberant balloon. Although in Fig. 7, for reasons of clarity, the stomach wall is not shown as being in contact with either the sleeve 20 or the electrodes 32, in practice, such contact will generally be made.
At this point, the RF ablation current can be applied to the electrodes, the current being pre-selected such that it ablates the mucosa, the submucosal layers, and at least most of the muscularis externa, leaving the serosa generally unaffected. If the full height embodiment of the type shown in Fig. 4 is used, then the current is preferably applied between adjacent pairs of electrodes, preferably one pair at a time, thereby treating the whole area of the walls one small region at a time. The RF current used is preferably within the frequency range of 460-480 kHz, since this frequency range results in effective thermal damage to the surface tissues, as desired, the tissues closing the RF circuit between adjacent electrodes. Although this frequency is proposed because its effects are well documented for this application, it is to be understood, however, that any other suitable frequency range may also be used, provided that under the ablation conditions used, the correct depth and adequate control of the ablation process is possible. Temperature sensors may preferably be installed in the protuberant element surface to measure the gastric wall temperature in order to monitor and control the ablation process. A closed loop control system may be incorporated, such that the RF input power is adjusted to provide optimal ablation conditions. The presence of the inflated sleeve balloon 20 protects the gastric wall 13 surrounding it from the effects of the RF ablation current. Even though there are no electrodes in that region, the sleeve protects this channel of gastric wall even from the effects of stray RF fields.
According to further preferred embodiments of the present invention, instead of using RF ablation to produce thermal damage to the stomach lining, a drug or chemical injected into the stomach lining can be used to damage it, such that the tissue scars or undergoes necrosis and shrinks.
After the ablation treatment, the protuberant element is re-stowed or deflated, the sleeve deflated, and the entire apparatus is withdrawn from the subject's stomach. After a period of time, as shown in Fig. 8, the necrosis of the ablated layers and the generation of the scar tissue from the thermal lesions results in substantial shrinkage of the stomach wall where the ablation treatment was applied. The gastric wall 20 in the region where the inflatable sleeve was positioned, on the other hand, remains essentially intact. Optimally, the two ablated opposite walls 81 close almost completely onto each other, such that only a channel of unaffected stomach remains where the inflatable sleeve was positioned, and the bulk of the stomach body collapses into a thin layer of non-functional tissue 80. The gastric volume is thus substantially reduced from its original volume.
The above embodiments have been described in terms of an unablated stomach pouch formed along the smaller curvature wall of the stomach, this location providing a natural path for the pouch since one half of the pouch wall is already in place at the smaller curvature,. However, it is to be understood that the invention is not intended to be limited to this position, but that the unablated pouch can be formed along any selected pathway along the stomach length. Such an embodiment is shown schematically in Fig. 9, which shows a system with a sleeve 90 positioned for generating a pouch close to the median line of the stomach. There is then need for two protuberant elements 91 , 92, on either side of the sleeve balloon, in order to ablate the stomach wall on either side of the unablated channel. In Fig. 9, the protuberant elements are shown full height, though it is to be understood that they can also be of partial height.
Although the invention has been described hereinabove in terms of the use of RF ablation, it is to be understood that it is not meant to be limited to RF ablation, and any alternative ablation process which can be readily applied is equally usable, such as the application of drugs or chemicals, cryo-ablation, laser ablation, water jet ablation, or the like. Each of these different methods will require the provision of the relevant application means, as is well known in the art. Whichever method is used, the sleeve ensures that the ablation process does not affect the areas of the stomach wall beneath the sleeve. Since in the case of the use of RF ablation, stray RF field may penetrate the protection sleeve if it is made of a polymer material, it may be necessary to provide an earth screen in the wall of the sleeve, or to make the sleeve of somewhat conductive material, in order to shield the stomach wall located beneath the sleeve from the effects of the RF.
It is appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of various features described hereinabove as well as variations and modifications thereto which would occur to a person of skill in the art upon reading the above description and which are not in the prior art.