Stomach R.B. Kolachalam, MD
Relevent Anatomy 1.four regions: Cardia, Fundus, Body, and the Pylorus 2. fixed in two locations- at the GEJ and the duodenum
Gastric Anatomy body of the stomach: site of mechanical agitation of food fundus: site of receptive relaxation
Arterial blood supply of the stomach Primarily from the Celiac artery left, and right gastric arteries right and left gastoduodenal arteries aberrant /replaced left hepatic artery from the left gastric artery (15-24%)
Arterial supply to the gastric conduit in esophagectomy is primarily based on the right gastroepiploic artery
Venous and lymphatic drainage corresponds to the arterial supply veins empty either directly into the portal vein or into one of its tributaries, the splenic or SMV Lymphatics form anastomosis in the gastric wall-hence the 5cm requirements for resection
Innervation of the Stomach left vagus-anterior, right vagus-posterior (LARP) Anterior and Posterior Nerves of Laterjet Crows feet at the incissura criminal Nerve of Grassi
Physiologic consequences of Vagotomy BAO-reduced by 80% exogenous stimulants (pentagastrin) -50 to 70% decrease endogenous stimulation-down by 70% altered emptying-loss of receptive relaxation of fundus leads to accelerated emptying of liquids
Gastric Physiology parietal cells-acid and intrinsic factor chief cells (pepsinogeneral is a chief) - pepsinogen G cells-gastrin ECL cells-histamine-stimulates parietal cells via cyclic AMP
Gastric physiology-cont secretin- s cells in duodenum and jejunuminhibits release of gastrin, gastric acid secretion and gastric motility. Bombesin (GRP) universl on switch. Somatostatin- off switch E-mycin stimulates motility through activation of motilin receptors
Gastric physiology Secretin: paradoxical increase in serum gastrin levels in patients with gastrinoma
H.Pylori implicated in : peptic ulcer disease chronic gastric atrophy and intestinal metaplasia-gastric cancer Malt lymphoma
H.pylori only human bacterium to persistently infect the stomach binds only to gastric-type of epithelium regardless of location 90-95% of DU and 70-75% of gastric ulcers are H.pylori positive Only 10-15% of infected people develop peptic ulcerations and only 1% develop gastric cancers.
H.pylori: virulence factors vacuolating cytotoxin A (VacA) cytotoxin-associated gene A(CagA)
H.pylori testing Invasive and non-invasive tests urea breath test, test of choice for documentation of H.pylori eradication
H.pylori treatment proton pump inhibitors, usually with two antibiotics, usually clarithromycin and flagyl,or amoxicillin. combination of antibiotics more effective, therapy for 7 or 14 days eradication rates over 90%
Gastric ulcer type 1: type A blood, other types associated with type O. on lesser curve. low acid secretion type 2: 2 ulcers-du, and lesser curve. High acid type 3: pre-pyloric. high associated type 4: high lesser curve-not associated with high acid type 5: NSAID induced, not related to H.pylori, no specific location
Gastric ulcer management unlike DU, less association with H. pylori, and reduced acid secretion medical management is to eradicate h.pylori. multiple biopsies needed to exclude malignant
Gastric ulcer-surgical therapy type 1 (60%): distal gastrectomy with B-1. Vagotomy not needed type 2, and 3 behave like DU and are treated as such. type 4: distal gastrectomy with extension along the lesser curve (Pauchet procedure),or Rouxen-Y. no vagotomy needed
Duodenal ulcers eradication of H. pylori reduces the recurrence rates to 6% prevalence of H.pylori lower in patients with complicated DU
Surgical management of DU? only indication for elective surgery-intractable recurrent symptoms of DU despite adequate medical treatment in the absence of H.pylori patients at high risk for ulcer complications (transplant recipients, steroid or NSAID dependency, giant ulcer)
Surgical management of DU parietal vagotomy-lower morbidity, but higher recurrence rates truncal vagotomy and B 1, or drainage procedures.
Complications of Peptic ulcers 1. Hemorrhage 2. Perforation 3. Gastric outlet obstruction
Hemorrhage from peptic ulcer disease initial resuscitation and medical management early endoscopy to assess the cause and severity, and treat endoscopically if possible prevention of recurrences with H.pylori eradication continued hemodynamic instability may need interventional radiology techniques or surgery
Bleeding Gastric ulcers need excisional therapy-distal gastrectomy with B-1, or in unstable patients ulcer excision or oversewing of the ulcer
Bleeding Duodenal ulcer three point ligation, and pyloroplasty. truncal vagotomy in stable patients H.pylori eradication
Complications of ulcer disease: perforation DU- omental patch closure, with post-operative H.pylori eradication GU- partial gastrectomy is prefered. In high risk patients-ulcer excision, or biopsy and over sew
Gastric outlet obstruction the most common cause of GOO in adults is malignancy Endoscopy is needed to rule out malignancy correction of acid and electrolyte imbalances, and hydration is key. make sure the patient is nutritionally optimized, and gastric tone regained. only 40% of patients have sustained improvement in 3 months distal gastrectomy is the usual operation of choice
Gastric Cancer Incidence is decreasing. M>F. Africanamerican>White 55% present with locally advanced or metastatic disease proximal gastric cancer s increasing
Gastric cancer: Histological subtypes: Intestinal diffuse
Intestinal type of Gastric Cancer distal stomach elderly atrophic gastritis, and diets high in nitrates, and nit rose compounds
Diffuse gastric cancer younger patients no identifiable precursor predilection for the cardia diffuse thickening worse prognosis not associated with H.pylori
Gastric cancer staging locoregional disease (AJCC stage 1-3) and systemic disease (AJCC stage 4) CT accuracy 70% for advanced disease and 44% for early disease EUS-superior to CT in the regional staging. Staging laparoscopy
Gastric Cancer: Controversies in surgical management Extent of gastric resection extent of lymph node dissection optima approach to proximal lesions role of splenectomy and adjacent organ resection role of neoadjuvant therapy for locally advanced gastric tumors
Extent of gastric resection R0 has survival benefit proximal margins of 5-6cm, with frozen section no benefit for total gastrectomy in distal cancers total gastrectomy for most cancers of the funds and proximal stomach esophagogastrectomy for tumors of the cardia and the GEJ
Lymph node dissection for gastric cancer D1,D2, or D3 dissection 15 nodes needed for pathological staging resection of pancreatic tail, spleen reserved for direct involvement
Adjuvant therapy of Gastric cancer combined chemoradiation is the standard adjuvant therapy in US. Adjuvant therapy is avoided in R0 resections in Europe.
Neoadjuvant therapy: Gastric cancer NCCN recommends neoadjuvant therapy for locally advanced (T3 or node + disease on EUS)
Gastric lymphoma non-hodgkin type B symptoms rare risk factors-h.pylori, immunosuppression, celiac disease, IBD, and HIV infection
Gastric lymphoma: management shift away from surgical management even in localized disease (stomach and perigastric nodes) 45% are MALT lymphoma s-treated with anti-h.pylori therapy. for localized persistent therapy radiation or chemotherapy is used for the 55% of high grade lymphoma s -treated with chemo and radiation surgery only for bleeding or perforation complications
GIST tumors stomach is the most common site-70% from the precursor of the interstitial cells of Cajal diagnosis is by staining for the KIT receptor (CD 117)- 95%.
GIST tumors avoid biopsy for resectable lesions tumor size and mitosis most important prognostic factors Negetive margins. no node dissection for moderate to high risk recurrence, adjuvant Imatinib-selective KIT inhibitor also used for borderline resectable lesions before surgery
Gastric Carcinoid three types. type 1 associated with chronic atrophic gastritis. type 2: associated with ZE syndrome and MEN- 1 type 3: (sporadic), biologically aggressive, no hypergastrinoma.
Gastric Carcinoid tumors endoscopic or open resection for type 1 and 2 tumors type 3 require gastric resection with ELND.