E2- Portosystemic shunt Flashcards by Crimson Cuppernell

Abnormal communications of the portal and systemic vasculature that allow products of intestinal absorption to bypass the liver and enter directly into the systemic circulation = ________

portosystemic shunt

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Extrahepatic PSS signlament

small dogs and cats

yorkies, shih tzu, maltese, poodle, schnauzer, dachshund, pugs

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Extrahepatic shunts: veins that should join the _____ enter the caudal vena cava or azygous vein instead

portal vein

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What 2 veins are most commonly involved in extrahepatic shunts?

left gastric vein and splenic (gastrosplenic)

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What veins are less commonly involved extrahepatic shunts?

direct portocaval

gastroduodenal

mesenteric (jejunal and colic veins)

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IIntrahepatic PSS signalment

Large breeds

labrador retriever, golden retriever, australian shepherd, old english sheep dog

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Intrahepatic shunts: intrahepatic branches of portal vein enter vena cava or hepatic vein by bypassing the ______

hepatic parenchyma

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What is portal vein atresia?

portal vein never developed

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portal vein atresia affects what vessels?

major pre-hepatic vessels

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Ascites is more common in what type of shunt?

portal vein atresia

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T/F: acsites is hyperproteinemia

FALSE- hypoproteinemia

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_____ occurs when shunt is partially occluded. Why?

Portal hypertension

bc blood cant get to liver, blood is backing up, can be fatal

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Portal vein atresia treatment

medical management

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Portal vein hypoplasia (PVH) is hepatic _____ dysplasia

microvascular

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Portal vein hypoplasia- ______shunting w/in the liver

microvascular

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Portal vein hypoplasia may occur as a single entity or in conjunction with _____-

macrovascular shunts

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Portal vein hypoplasia clinical signs

may not have very many

abnormalities in liver function but not super noticible

may only show up in middle age

drug “sensitivity”

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Laboratory tests for Portal vein hypoplasia

may have minimal or no alterations in routine testing
bile acids often only mildly elevated (postprandial often <100)
protein C activity- tells you if there is blood flow to the liver
- >70%
- plasma anticoagulant factor synthesized in liver
- reflects hepatic synthetic activity and portal blood flow

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Portal vein hypoplasia- Nuclear scintigraphy: shunt fraction near normal (~15%) compared to _____

PSS (>70%)

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Treatment of stable form of portal vein hypoplasia

none- just need to know its there

medical management- diet is often enough

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Treatment of progressive form of portal vein hypoplasia

(extensive liver involvement)

pathophysiology similar to uncorrected macrovascular shunts

diet- restrict protein levels

medical management

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Multiple extrahepatic PSS is secondary to diseases the cause _______

portal hypertension

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Multiple extrahepatic PSS secondary to ______ shunt ligation

macrovascular

-liver hasnt been getting normal blood supply so it may not be able to handle all the blood= portal hypertension

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T/F there can be either cirrhosis or no cirrhosis with multiple extrahepatic PSS

true

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2 examples of non-cirrhotic portal hypertension

idiopathic portal hypertension hepatic veno-occlusive dz

\_\_\_\_\_\_ can open up preventing lethal portal hypertension from developing

vestigial embryonic communications

Macrovascular shunt diagnosis

signalment and hx physical exam hematology, biochem, urinalysis liver function tests rads (survey and contrast) US nuclear scintigraphy**-** technetium 99 tells you shunt is present exploratory celiotomy

Most diagnostic test for macrovascular shunts? What if P is already open for surgery?

CT angiography portography if P is open

Macrovascular shunt general signs

poor growths rates- runts, weight loss, anesthetic and tranquilizer intolerance (bc liver cant metabolize drugs- may take very long time to recover after anesthesia)

Macrovascular shunt nervous system signs

toxins not being taken out by liver lethargy, depression, weakness, behavior, pacing, aggression, ataxia, stupor, head pressing, coma, seizures

Macrovascular shunt GI signs

anorexia, vomiting, diarrhea, ptyalism, pica, ascites

Macrovascular shunt urinary system signs

PU/PD, cystitis, urolithiasis- _urate_ stones, urethral obstruction

Cats that have copper colored irises, hypersalivation and aggressive behavior are likely to have \_\_\_\_\_\_

Macrovascular shunt

Acsites is uncommon with congenital PSS unless severely \_\_\_\_\_\_

hypoproteinemic (poor prognostic sign) severe portal vein hypoplasia, portal vein atresia

Protein C activity differentiates between macrovascular and microvascular shunts -how?

\<70% macro \>70% micro

Postprandial bile acids differentiate between macrovascular and microvascular shunts -how?

\<100 micro \>100 macro

Urinalysis on a animal with macrovascular shunt

ammonium biurate crystals- like seen in dalmations multiple UAs may be necessary

US for macrovascular shunts

need a good radiologist- intrahepatic shunts consistently identified extrahepatic shunts- more difficult to see, can determine location of shunt, gas/food in stomach obscures vision, weight may compress shunt vessel

What is a non invasive method of documenting PSS that may require radiation isolation?

Nuclear scintigraphy- technetium 99 (transcolonic- can identify presence or trans-splenic- can identify type)

What diagnostic method is 5.5 times more likely to correctly determine presence or absence of PSS compared to abdominal ultrasonography?

CT angiography- **noninvasive** ## Footnote **most diagnostic**

If a patient is open for surgery and we want to test for macrovascular shunt, what method is best?

Portography- invasive mesenteric vein injection

T/F: Portography should be done along with CT angiography

FALSE- Portography not necessary if preop CT angiography performed

What is the suggested medical treatment for macrovascular shunts?

diet- protein restricted lactulose antimicrobials sz control/prevention control intestinal parasite

What does albumin have to do with preop consideration for shunt surgery?

if **less than 1.5**mg/dl - surgery is much **risk**ier

Explain what the goal of surgical intervention is

to 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 to improve liver function canNOT happen w/ medical tx

When exploring the abdomen, where are you looking for extra-hepatic shunts?

epiploic foramen ometal bursa esophageal hiatus

\_\_\_\_\_\_ complete occlusion w/out causing signs of portal hypertension. Possible in how many cases?

Ligation possible in \<1/2 cases

\_\_\_\_\_\_\_- vessel is partially occluded

attenuation shunt may occlude spontaneously due to inflam or altered blood flow mechanics. If that doesnt happen usualyy re-operate and occlude shunt completely

Maximum change in portal pressure b/t pre and post ligation is \_\_\_\_\_\_\_\_

9-10 cm H2O we dont want it to go over 10

Ameroid constrictor reasons for acute complications?

rapid closure, kinking

Ameroid constrictor- chronic complications

incomplete occlusion acquired shunts (~20% of cases) implant migration- just the ring itself probably not be a problem

With cellophane banding, occlusion is entirely by \_\_\_\_\_\_

inflam rxn

Cellophane banding typically occludes completely within \_\_\_\_\_

8-12 days if occluded to \<3mm if larger takes longer variable results in cats

Advantages hydraulic occluders

single surgery w/o portal pressure, gradual and total vascular occlusion, reversible

Disadvantages hydraulic occluders

implant leakage or diffusion, potential for additional manipulation, long term?

Extravascular occlusion of shunts- procedure is similar to extrahepatic techniques but....

pre-hepatic post-hepatic

Intravascular occlusion includes what 3 types?

intracaval transportal thrombogenic coils

List acute post-op complications with shunt sx

portal hypertension portal vein thrombosis hypoglycemia szs- 4-6% incidence in patients with no prior history hemorrhage electrolyte disturbances- hyponatremia often iatrogenic

How long post-op shunt sx do we continue fluid therapy?

until they are recovered from anesthesia

T/F after shunt sx we want to withhold food

FALSE- encourage early food intake

Why must we monitor vital signs and abdomen after shunt sx?

for signs of hypertension

T/F we need to monitor for seizure activity post-op shunt sx

True- eyelid twitching frequent prodromal sign

How long do we wait until we recheck after shunt sx? what do we check?

4-8 weeks minimum routine bloodwork liver function test- goal is to get them normalized! **protein C activity**

What happened if we have abnormal post-op lab tests?

there is significant continued shunting * vessels never completely occluded * there was more than one shunt * you occluded the wrong vessel * multiple acquired shunts formed due to portal hypertension * significant MVD is present follow up US, nuclear scintigraphy or CT angiography

Long term outcome of extrahepatic shunt sx?

good to excellent 78-94%

Long term outcome for intrahepatic shunt sx?

good to excellent 50-89%

What is the prognosis of shunt surgery for cats?

75% post op complications good to excellent outcome- 30-80%