PSS Flashcards
abnormal communications of the portal and systemic vasculature that allow products of intestinal absorption to bypass the liver and enter directly into systemic circulation
portosystemic shunts
T/F
extrahepatic shunts are microvascular
false - macro
what is the signalment for extrahepatic shunts
small dogs - YORKIES
what veins are most commonly involved in extrahepatic shunts
left gastric v
splenic v
in an extrahepatic shunt, veins that should join the portal vein enter where instead
the cd vena cava or the azygous
what should normally be the last vessel to enter the cd vena cava
phrenicoabdominal (drains the adrenal)
intrahepatic shunt
macrovascular - large dogs like labs, goldens, old english sheepdogs, and ausseis
pathophysiology of intrahepatic shunts
patent ductus venosus - shunting vein within the hepatic parenchyma because it did not close at birth
hepatic parenchyma is bypassed
when there is no portal vein at all
portal vein atresia
what vessels are affected by portal vein atresia
major pre-hepatic vessels
what is the most common sign of portal vein atresia
ascites due to hypoproteinemia
surgical treatment for portal vein atresia
NONE - medical management only
microvascular shunting within the liver
portal triad is too small
portal ein hypoplasia
or
hepatic microvascular dysplasia
sign of portal vein hypoplasia
drug sensitivity
post prandial bile acids < 100
protein C acitivty > 70%
plasma anticoag factor synthesized in the liver that reflects hepatic synthetic activity and portal bloodflow
protein C
shunt fraction on nuclear scintigraphy of PSS and of PVH
PVH - near normal 15%
PSS - >70%
macrovascular shunt general signs
poor growth rate
weight loss
anesthetic and tranquilizer intolerance
macrovascular shunt nervous system signs
lethargy depression weakness pacing aggression ataxia stupor coma seizures head pressing blind
macrovascular shunt GI signs
anorexia vomit diarrhea pytalism - cats mostly pica ascites
macrovascular shunt urinary signs
pu/pd urolithiasis - liver cannot conjugate ammonium properly ammonium biurate crystals cystitis urethral obstruction
cats with agressiveness, copper eyes, hypersalivation
macrovascular shunt
HAV malformation
bruit
biochem for macrovascular shunt
low BUN ALB CHOL
high ALT ALP
macrovascular protein c
<70%
who can get ammonium biurate crystals
dalmatians
and macrovascular shunts
noninvasive method of documenting PSS
nuclear scintigraphy – distinguish from microvascular dysplasia but cannot tell intra vs extrahepatic
what is the isotope used in nuclear scintigraphy
tachnetium 99 - given transcolonic or trans-splenic
noninvasive dx modality that is 5.5x more likely to correctly determine presence of absence of PSS compared to ultrasonography
CT angiography
most common but invasive diagnostic method
portography - mesenteric vein injection
not needed if pre op ct angiography is done
false negatives
preop ALB levels that make risky surgery
<1.5 mg/dl ALB = risky
goal of surgery
improve liver function
divert blood flow back through portal system without creating portal hypertension severe enough to be life threatening or high enough or long enough to cause acquired shunts to open up
what three areas should be checked for the shunt in exploratory
epiploic foramen
esophageal hiatus
omental bursa
ideal surgical mgmt of PSS
complete ligation - complete occlusion without causing signs of portal hypertension
possible in only 1/2 cases
attenuation
vessels only partially occluded
Maximum change in portal pressure between Pre and post ligation
9-10cmh2o
occlusion entirely by inflammatory reaction
cellophane banding
typically occludes completely in 8-12 days if occluded to <3mm
post op - recheck in how many weeks min
4-8
