fig1 is a front cross - sectional view of the esophageal - gastro - intestinal tract 40 from a lower portion of the esophagus 41 to the duodenum 42 . the stomach 43 is characterized by the greater curvature 44 on the anatomical left side and the lesser curvature 45 on the anatomical right side . the tissue of the outer surfaces of those curvatures is referred to in the art as serosa tissue . as will be seen subsequently , the nature of the serosa tissue is used to advantage for its ability to bond to like serosa tissue . the fundus 46 of the greater curvature 44 forms the superior portion of the stomach 43 , and traps gas and air bubbles for burping . the esophageal tract 41 enters the stomach 43 at an esophageal orifice 58 below the superior portion of the fundus 46 , forming a cardiac notch 47 and an acute angle with respect to the fundus 46 known as the angle of his 57 . the lower esophageal sphincter ( les ) 48 is a discriminating sphincter able to distinguish between burping gas , liquids , and solids , and works in conjunction with the fundus 46 to burp . the gastroesophageal flap valve ( gefv ) 49 includes a moveable portion and an opposing more stationary portion . the moveable portion of the gefv 49 is an approximately 180 degree , semicircular , gastroesophageal flap 50 ( alternatively referred to as a “ normal moveable flap ” or “ moveable flap ”) formed of tissue at the intersection between the esophagus 41 and the stomach 43 . the opposing more stationary portion of the gefv 49 comprises a portion of the lesser curvature 45 of the stomach 43 adjacent to its junction with the esophagus 41 . the gastroesophageal flap 50 of the gefv 49 principally comprises tissue adjacent to the fundus 46 portion of the stomach 43 , is about 4 to 5 cm long ( 51 ) at it longest portion , and the length may taper at its anterior and posterior ends . the gastroesophageal flap 50 is partially held against the lesser curvature 45 portion of the stomach 43 by the pressure differential between the stomach 43 and the thorax , and partially by the resiliency and the anatomical structure of the gefv 49 , thus providing the valving function . the gefv 49 is similar to a flutter valve , with the gastroesophageal flap 50 being flexible and closeable against the other more stationary side . the esophageal tract is controlled by an upper esophageal sphincter ( ues ) near the mouth for swallowing , and by the les 48 and the gefv 49 at the stomach . the normal anti - reflux barrier is primarily formed by the les 48 and the gefv 49 acting in concert to allow food and liquid to enter the stomach , and to considerably resist reflux of stomach contents into the esophagus 48 past the gastroesophageal tissue junction 52 . tissue aboral of the gastroesophageal tissue junction 52 is generally considered part of the stomach because the tissue protected from stomach acid by its own protective mechanisms . tissue oral of the gastroesophageal junction 52 is generally considered part of the esophagus and it is not protected from injury by prolonged exposure to stomach acid . at the gastroesophageal junction 52 , the juncture of the stomach and esophageal tissues form a zigzag line , which is sometimes referred to as the “ z - line .” for the purposes of these specifications , including the claims , “ stomach ” means the tissue aboral of the gastroesophageal junction 52 . fig2 shows a device 60 embodying the present invention . as will be seen hereinafter , the device 60 permits transesophageal gastric reduction for treating severe obesity . the device 60 generally includes an expandable structure 70 and an evacuator 80 . shown further in fig2 is a fastener 90 which the device 60 delivers to maintain a formed gastric reduction pouch . the expandable structure 70 , in accordance with this embodiment , takes the form of an inflatable ring - shaped balloon 72 which is integrally formed on and carried by an outer catheter 74 . the ring - shaped balloon 72 and catheter 74 define an axial passageway 76 . the balloon may be a compliant balloon formed of latex or polyurethane , for example . it may alternatively be a non - compliant balloon formed of polyethylene . a non - compliant balloon may be preferred as it maintains a fixed shape and size once totally inflated rendering the size of the balloon is rendered predictable . the evacuator 80 , in accordance with this embodiment , comprises an endoscope 82 which includes a light source 84 , a viewer 86 , and a working channel 88 . endo scopes of this type are well known in the art . the working channel 88 is employed for evacuating the stomach once the device 60 is in place within the stomach and the balloon 72 has been inflated . this will become more apparent subsequently . as will be noted in fig2 , the evacuator 80 extends through the expandable structure 70 . more specifically , the endoscope 82 may be advanced through the axial passageway 76 to terminate distal to the expandable structure 70 to facilitate the evacuation of the stomach . the fastener 90 may be carried by the endo scope 82 and also advanced through the axial passageway 76 along the endoscope 82 by a tubular pusher 100 . the fastener 90 is preferably formed of a shape memory material such as nitinol or a shape memory plastic , for example , so as to be self - deploying when advanced past the distal end 78 of the catheter 74 . it alternatively may be formed of stainless steel but would then require forced expansion as , for example , a balloon as is well known in the art . fig3 illustrates the fastener 90 during an initial stage of its deployment . the fastener 90 prior to its deployment takes the form of a cylindrically shaped member 92 having opposed ends from which first and second sets of tissue engaging arms radially extend after deployment . as will be noted in fig3 , a first set of tissue engaging arms 93 are radially extending from the cylindrical member 92 as the fastener 90 is advanced by the catheter 100 past the distal end 78 of the catheter 74 . upon further displacement of the fastener 90 as illustrated in fig4 , the cylindrical center portion of the cylindrical member 92 is exposed . this forms a channel through which ingested food may pass out of the gastric reduction pouch after it is formed and maintained by the fastener 90 . referring now to fig5 , it illustrates an initial stage of forming the gastric reduction pouch in accordance with the present invention . here it will be seen that the expandable structure 70 has been advanced through the esophagus 41 on the catheter 74 so that it is placed in the stomach immediately adjacent and distal to the esophageal orifice 58 . after the expandable member is positioned adjacent the esophageal orifice 58 , the endo scope 82 is advanced through the axial passageway of the catheter 74 and expandable structure 70 until it is distal to the catheter 74 and expandable structure 70 within the stomach 43 . after the expandable structure 70 and endo scope 82 are placed in the stomach 43 as illustrated in fig5 , the expandable structure 70 is expanded to define the size and shape of the gastric reduction pouch to be formed . in accordance with this preferred embodiment , the expandable structure 70 comprises a balloon 72 which may be inflated as illustrated in fig6 . here it may be seen that the balloon 72 has been inflated and occupies a fraction or portion of the stomach 43 . the balloon 72 may be inflated through a lumen ( not shown ) in the catheter 74 in a manner well known in the art . after the balloon 72 has been expanded to its desired size , the stomach 43 is evacuated through the working channel of the endoscope 82 to cause the stomach to be drawn around the balloon 72 . once the stomach tissue has been drawn around the balloon 72 , the fastener 90 is then advanced down the endoscope 82 by the pusher 100 for deploying the fastener 90 . as shown in fig7 , the fastener 90 is partially deployed with the first set of tissue engaging arms 93 radially extending from the cylindrical body 92 of the fastener 90 . upon further advancement of the fastener 90 as illustrated in fig8 , the second set of tissue engaging arms 95 are released from the catheter 74 to radially extend from the cylindrical body 92 of the fastener 90 . the shape memory of the fastener 90 may be used to advantage by which the opposed sets of radially extending tissue engaging arms 93 and 95 together with the drawing of the stomach around the balloon 72 inwardly folds the outer surfaces of the stomach 43 to cause contact between adjacent outer surfaces of the stomach about the cylindrical body 92 of the fastener 90 . the outer surface of the stomach comprises serosa tissue which develops a bond after contacting like tissue within a short period of time . this bond between the outer surfaces of the contacting stomach tissue will assist the fastener 90 in maintaining the gastric reduction pouch thus formed . once the fastener 90 has been fully deployed as illustrated in fig8 , the assembly and device 60 is removed from the stomach . this may be achieved by first drawing the pusher 100 out of the catheter 74 . then , the balloon 72 may be deflated permitting the balloon 72 and catheter 74 to be withdrawn from the stomach on the endoscope 82 . lastly , the endoscope 82 may be withdrawn through the fastener 90 , through the gastric reduction pouch formed by the assembly and device 60 , and the esophagus 41 . this leaves the esophageal - gastro - intestinal tract 40 in a condition as illustrated in fig9 . here it may be seen that the gastric reduction pouch 110 has been formed between the esophagus 41 and the remaining stomach 43 . the fastener 90 may remain in place to maintain the gastric reduction pouch 110 . the gastric reduction pouch 110 presents a smaller volume to accommodate ingested food thus providing the patient with an earlier sense of being full and a longer time of feeling full . as will be noted from the foregoing , the process of forming the gastric reduction pouch 110 with the device 60 embodying the present invention has been performed in a transesophageal manner without the need of any surgical incisions . hence , the therapy contemplated herein is much less invasive than previous therapies for providing gastric reduction therapy . all of the advantages of gastric reduction therapy are available while substantially reducing the risks attendant to general surgery . while particular embodiments of the present invention have been shown and described , modifications may be made , and it is therefore intended in the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention .