B49 part 2, Vascular disorders of GI

Question 1

What are the categories of infarctions in the intestine?

What si the general cause of them?

Answer 1

Mucosal

Mural

Transmural

Mucosal and Mural infarctions involve the mucosa and submucosa, and are caused by hypoperfusion or hypovolemia rather than acute total obstruction.

Transmural infarcts go through all 3 layers and are caused by total acute obstruction of either and artery or a vein of that region.

Question 2

What are predisposing factors to develop intestinal ischemia?

Answer 2

• atherosclerosis with eroded or ruptured plaques causing arterial thrombi
• aortic dissection obstructing the major mesenteric arteries
• Systemic vasculitis
• Arterial embolii
  
  • fat emboli from ruptured plaques
  • vegetative embolism from endocarditis
  • fat embolism after angiographic proceedures
• Venous thrombosis from hypercoagulable states
  
  • cirrhosis and portal vein stasis/hypertension
  • vascular invasive neoplasms, like hepatocellular carcinoma
• Radiation injury
• Strictures or intussusseption and vessel obstruction
• Angiodysplasia

Question 3

Difference between a slow developing obstruction of GI vessels and acute obstruction

Answer 3

Slow obstructions are well compensated for due to the many anastomoses

This is also why the GI is a site of hemorrhagic necrosis during ischemia, from the multiple blood supplies and relow of blood into the damaged area.

Question 4

What are the clinical features of a transmural infarction?

Mural/mucosal infarctions?

Answer 4

Transmural infarctions present as sudden abdominal pain, and may have bloody diahhrea and may vomit. Abdominal sounds halt, and muscular spasm causes strong abdominal musclar defensive contraction.

The hemorrhagic necrosis will rapidly progress to hypovolemic shock and death if not treated, and presents a high risk for sepsis during treatment.

Mural/mucosal infarctions. Will have mild and more gradual onset of pain. Often cause GI bleeding which may be occult or bloody diarrhea. They are rarely life threatening.

Chronic ischemia will cause recurring mild mural or mucosal infarctions, and may be misdaignosed as inflammatory bowel disease.

Question 5

What is angiodysplasia?

Answer 5

Malformations of the blood vessels in the submucosa and mucosa of the intestines, which are tortuous and dilated. Account for 20% of the major episodes of lower intestinal bleeding.

These vessels are prone to rupture, and can cause mild intraluminal bleeding, or massive hemorrhage and lethal shock.

Occurs in elderly, usually after the 60s. Idiopathic.

Most often in the Cecum or right Colon

Question 6

Hemorrhoids, clinical presentation and consequences

Answer 6

Varicose vein dilations of the veins around the anal canal

Superior/middle rectal veins line the columns of morgani and when they dilate produce internal hemorrhoids

Inferior rectal veinsare on the exterior of the anus and dilate to form external hemorrhoids.

They are thin walled submucosal vessels. They become inflammed and filled with thrombii which are eventually recanalized. These thrombii don’t cause further comploications.

They may cause bleeding but it is not an emergency, and can be surgically ligated or removed.

The main complication is pain and bleeding that is unsettling.