Читать книгу Small Animal Surgical Emergencies - Группа авторов - Страница 239

The terms “torsion” and “volvulus” are often used interchangeably. Torsion (from L. torquere, to twist) is a twisting of a structure on its long axis with one end fixed. Mesenteric torsion is a pathological rotation of the intestinal tract around the axis of the mesenteric root, resulting in rapid occlusion of the cranial mesenteric artery [1]. By necessity, mesenteric torsion involves all the intestine supplied by the cranial mesenteric artery and its branches. Intestinal volvulus (from L. volvere, to roll or turn) refers to twisting of the intestine upon itself at any point, causing obstruction. By definition, then, intestinal volvulus necessarily occurs whenever there is mesenteric torsion; however, intestinal volvulus may occur in isolation (segmental intestinal volvulus) without the presence of true mesenteric torsion. For this reason, the most accurate term to use is “intestinal volvulus” and is the term that is used preferentially in this chapter when further specificity is not warranted.

The cranial mesenteric artery branches to form the jejunal, ileocolic, right colic, middle colic, and pancreaticoduodenal arteries (Figure 9.1). Occlusion of the cranial mesenteric artery impairs blood flow to the majority of the intestinal tract, leading to ischemic necrosis, gastrointestinal toxin release, and shock [1]. Both mesenteric torsion and intestinal volvulus can result in mechanical obstruction of the intestine. With complete torsion of the mesenteric root, there is complete occlusion of mesenteric blood flow (Figure 9.2). The occlusion of blood flow leads initially to venous and lymphatic obstruction and subsequent bowel wall edema with vascular engorgement, and results in mucosal sloughing and hemorrhage into the intestinal lumen. With unchecked progression of these changes, the disease process rapidly leads to patient death. Patients that survive probably suffer from incomplete mesenteric torsion, in which some blood supply is maintained, or suffer from volvulus of only a portion of the intestinal tract.