The term Ileal Interposition, in brief, is a kind of exchange of the initial and final parts of the small intestine. The insulin resistance hormones, Ghrelin (stomach), GIP (duodenum) and glucagon (pancreas), are excreted from the initial parts of the digestive system and the insulin sensitivity hormone, called GLP-1, is released from the L cells in the last part of the intestine. GLP-1 is a hormone that increases the effects of insulin and stimulates insulin production by the pancreas. Basically, the goal of this procedure is to leave the resistance hormones aside and increase the sensitivity hormones.
The final part of the intestine is called the Ileum. Displacing the last part of the small bowel (ileum) surgically is called ‘Ileal Interposition’.
Not only is an area of the last part of the intestine displaced by this surgery, but also a part of the stomach is removed, in order to create other hormonal changes in a manner that strengthens the effect of the Ileal Interposition surgery. The levels of a hormone, called Ghrelin, excreted from the upper left part of the stomach, are diminished by removal of this part of the stomach.
There are two important functions of ghrelin:
- To send impulses to the brain centre called the Hypothalamus, at the base of the brain, in order to create and/or increase feelings of hunger.
- Intra-cellular insulin resistance.
There is another important reason to remove this part of the stomach in Ileal Interposition surgery: in the event that the ileal displacement is only made on the intestines but without any procedure on the stomach, then gastrectasia that is called Gastric Dilatation occurs, plus persistent nausea and vomiting seizures are present. For the reason of these 3 effects, the left upper outer part of the stomach, known as the fundus, is removed.
The ghrelin hormone that has been excreted excessively, especially in Type 2 Diabetics, goes down to very low levels by the removal of the fundus of the stomach. Additionally, having the proximal and distal parts of the small bowel exchanged during the Ileal Interposition surgery aids in patients not feeling very much hunger, even if they do not eat for a long time in the post-operative period.
Therefore, the objective in removing a part of the stomach in the Ileal Interposition surgical operation is not, as a matter of fact, to reduce the volume of the stomach. The objective, in this respect, is to bring down the excretion levels of the ghrelin hormone triggering the feelings of hunger and to prevent the state of gastric dilatation that may emerge subject to a displacement at the intestine and occurring together with resistant nausea-vomiting. The stomach is left wider than the ‘tube stomach’ surgical operation (sleeve gastrectomy) that is done for morbid obesity. The reason for less food consumption by the patients post-operatively is the new internal arrangement, constituting hormonal changes. As a consequence of this, not withstanding that the Ileal Interposition surgical operation is an advanced digestive system surgery from the anatomical point of view, it completely turns out to be a ‘Metabolic Surgical Operation’ process when it is looked at in respect of the mechanisms that are affected. Each step that is applied in the Ileal Interposition surgical operation has a hormonal target. These objectives are assessed in consideration of various numbers of factors for each individual patient, and relevant changes may be made to the process according to the specific situation of the patient. Within this framework Ileal Interposition may be said to be a dynamic decision-making process.