Pathophysiology of Upper GI Bleeding

Ahmad abid abas Pathophysiology of Upper GI BleedingPathophysiology of Esophageal VaricesConsequence of Portal HTN.The initial factor in portal HTN is the increase in vascular resistance to portal blood flow.This will lead to structural distortion (underlying disease) and active contraction of portal/septal cells (hepatic cells,myofibroblasts) in portal venules. (the dynamic component).This will lead to development of porto-systemic collaterals (possibly from influence of angiogenic factors, VGEF) will cause shunting of blood around liver.

http://bestpractice.bmj.com/best-practice/monograph/815/basics/pathophysiology.htmlUlcer related UGIBPeptic ulcer disease is strongly associated withH pylori infection.Causes disruption of the mucous barrier and has a direct inflammatory effect on gastric and duodenal mucosa.As the ulcer burrows deeper into the gastroduodenal mucosa, weakening and necrosis of the arterial wall, development of a pseudoaneurysm. The weakened wall ruptures, hemorrhage.

http://emedicine.medscape.com/article/187857-overview#aw2aab6b2b2aa

Acute stress gastritis in UGIB

Acute stress gastritis results from predisposing clinical conditions that have the potential to alter local mucosal protective barriers, such as mucus, bicarbonate, blood flow, and prostaglandin synthesis.Examples :Hypersecretion of acid. (Zollinger-Ellison syndrome)Defects in gastric glycoprotein mucous. ( In critically ill patients, increased refluxed bile salts or presence uremic toxins)Ischemia (Shock,sepsis and trauma can lead to impaired perfusion of the gut)Long term use of NSAIDs (inhibiting cyclooxygenase, decreased mucosal prostaglandin synthesis,will lead to impaired mucosal defenses)

http://emedicine.medscape.com/article/187857-overview#aw2aab6b2b2aa

Mallory Weiss tears15% of acute upper GI hemorrhage.Results from a tear in the mucosa of the gastric cardia.As consequence of forceful vomiting, retching, coughing, or straining.These actions create a rapid increase in the gradient between intragastric and intrathoracic pressures, gastric mucosal tear from the forceful distention of the gastroesophageal junction.

http://emedicine.medscape.com/article/187857-overview#aw2aab6b2b2aa