Vascular GI Diseases (Tombazzi and Nichols) Flashcards
The main arteries involved in GI vascular support include
celiac trunk, superior mesenteric artery and inferior mesenteric artery
What is the most sensitive artery to ischemic events
SMA
Superior mesenteric is responsible of giving the vascular support to
pancreatico-duodenal area
small intestine
right colon
the SMA terminates as the
ileo-colic artery
provides protection from ischemia in setting of segmental vascular occlusion
collateral circualtion
accounts for a wide fluctuation in splanchnic blood flow
Changes in the resistance of mesenteric arterioles
hormones that cause vasoconstriction of GI arterioles
catecholamines
Ang II
vasopressin
**secreted during shock and heart failure
hormones that cause vasodialtion of GI arterioles
gastrin
CCK
secretin
**secreted after mealtime
describe the intracellular signal responsible for vasodilation
production of NO
describe the intracellular signal responsible for vasoconstriction
activation of PLC –> IP3 –> release of Ca from SR
most sensitive part of the GI tract/will die first
top of the villi
**as ischemia persists, necrosis will progress down towards/thru the wall
How much of the bowel wall must be infarcted for you to clinically see rebound tenderness
to the serosa = transmural
clinically how does a mucosal infarct present?
bleeding
How much of the wall must be infarted to clinicallt see ileus?
villi/mucosa must be gone = mural or transmural
Causes of acute ishemia involving small bowel
- embolism from L side of heart to SMA
- thrombosis of SMA
- non-occusive ischemia (HF or shock)
- Mesentreric venous thrombosis (hypercoag state–think autoimmune dz)
- neoplasm or vasculitis
* *Goljian
radiographic findings seen with small bowel infarction
thumbprinting = due to edema in lamina propria
bowel distension with air fluid level
**Goljian
Common pathogenesis and presentation of ischemic colitis
Pathogen: artherlosclerosis of SMA
Presents: pain and tenderness (at splenic flexure commonly) ,hematochezia
**Diffuse disease of small vessels (diabetes mellitus, vasculitis) can also lead to this
Outcome of ischemic colitis
generally benign, but fibrosis can lead to strictures and obstruction
What part of the GI tract does ischemic colitis typically invovle
watershed/splenic flexure and rectosigmoid area
rarely rectum
Presentation of acute mesenteric ischemia
early: abdominal pain, NO ileum
later: rebound tenderness and ileus
* *there is NOT always blood
What does portal vein gas indicate?
air from lumen of GI is getting into venous system (??? i think thats what he said??) or bacteria colonizing venous system is producing gas
term used to describe dead bowel
dusky
pseudomembrane and mucin depletion is assc with acute or chonic bowel ischemia
acute
hyalinization and withering of crypts is assc with acute or chonic bowel ischemia
chronic
gangrenous necrosis, pneumatosis intestinalis and segmental absence of muscularis propria
Neonatal necrotizing enterocolitis (NEC)
How is ischemic colitis distinguished from acute mesenteric ischemia
IC: > 60 yo, not an acute cuase, mild pain and tenderness, bleeding
AMI: any age, usually acute, severe pain, tenderness appears late, uncommonly assc with bleeding
Hallmark presentation of chronic bowel ishemia
abdominal pain after eating –> weight loss
** 2 of the 3 splanchnic arteries usually have significant occlusive disease
most common cause of chronic ischemia
artherlosclerosis
time course to presentation of venous mesenteric ischemia relative to arterial
venous takes longer–several days
upper vs. lower GI bleed is distinguished as being above or below …
the ligament of Treitz
**attaches jejunum/duodenum to diaphragm
upper or lower acute GI bleed is more common
upper
epidemiology of acute upper GI bleed
men and the elderly
T or F: most acute upper GI bleeding requires intervention
F: 80% are self limiting
causes of acute upper GI bleed
Peptic ulcers Gastritis and duodenitis Tumors Vascular malformation Esophagitis Varices Other
Endoscopy can predict the risk of re-bleeding in duodenal ulcers. what finding on endoscopy is assc with the greatest risk of re-bleeding? lowest?
active bleeding
white ulcers
duodenal ulcers located ___ are most likely to bleed and rebleed
high on lesser curvature of stomach (how is this a duodenal ulcer, but whatevs?) and inferior wall of the duodenal bulb
are gastric or duodenal ulcers more likely to bleed
duodenal
esophageal varcies are often secondary to
portal HTN and cirrhosis
**Predictive factors fro bleeding include size and grade of liver dysfunction
treatment for esophageal varices
endoscopic banding
Gastric varices may occur as a result of …
plenic vein thrombosis resulting from pancreatitis or pancreatic malignancy
caused by forceful gastric mucosa prolapse with retching
Mallory-Weiss Tear
Treatment of Mallory Weiss Tear
80-90% spontaneously resolve so only need to stabilize patient
What infections can cause upper GI bleed
CMV and Herpes
What is the most common cases of acute lower GI bleeding
diverticulosis and angiodysplasia
What is the most common cases of chronic lower GI bleeding
hemorrhoids and neoplasia
What causes the bleeding in diverticulosis
results from penetration of a colonic artery into the dome of a diverticula
What is angiodysplasia?
degenerative change in blood vessels (become tortuous and dilated) then then bleed
Where in the GI tract does angiodysplasia typically occur?
cecum and right colon
**usually multiple of them at once
angiodysplasia can be secondary to…
advanced age, chronic renal failure, prior radiation (if in rectum), watermelon stomach, osler-weber-rendu
what are hemorrhoids
a real pain in the ass!! badadum…
Variceal dilations of anal and perianal venous plexus
hemorrhoids develop secondary to
persistent elevated venous pressure
constipation, pregnancy
What is the difference between external and internal hemorroids?
External hemorrhoids:
from inferior rectal vein, below pectinate line, PAINFUL
Internal hemorrhoids:
superior rectal vein, above pectinate line, PAINLESS