Surgical Management of Portosystemic Shunts Quiz

1
Surgical Management of Portosystemic Shunts Quiz

• Elaina Turner

2
What are the classifications of portosystemic
shunts (PSS)?

• Congenital or acquired
• Single or multiple
• Intrahepatic or extrahepatic
• Extrahepatic the anomalous vessel is located
  outside the hepatic parenchyma
• Intrahepatic the anomalous vessel is located
  within the hepatic parenchyma

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Which type may occur secondary to another type?

• Multiple extrahepatic acquired shunts

4
What is the etiology of multiple acquired
extrahepatic shunts?

• Occur secondary to a condition that causes
  elevated intrahepatic venous pressure

5
List 3 specific causes of multiple extarhepatic
shunts.

• Congenital portosystemic shunt
• Hepatic fibrosis of any cause
• Surgical attenuation of congenital shunt

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List three common forms of this type of shunt.

• Portocaval
• Portoazygous
• Splanchnic-caval, often gastrosplenic-caval
• Splanchnic-azygous

7
What is the common signalment of the patient with
a congenital intrahepatic shunt?

• Usually young animals
• Breed IWH, golden and labs, Siberian husky,
  Irish setter, other medium and large breeds of
  dogs and cats of any breed

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What is the most common form of this shunt?

• Patent ductus venosus

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What are the organ systems involved in CS of
congenital PSS?

• CNS
• Urinary
• Gastrointestinal
• Stunted growth

10
Describe the common signs seen for each of the
involved systems.

• CNS
• Hepatic encephalopathy (depression, behavior or
  temperament changes, dementia, seizure, collapse)
  
• Signs often worse after high protein meal
• Hypoglycemia
• Urinary ? PU/PD
• Gastrointestinal ? vomiting, diarrhea, ptyalism
  (cats)
• Stunted growth

11
What are the common biochemical abnormalities
seen?

• Elevated pre and post-prandial serum bile acid
  concentrations
• Low BUN
• Hypoglycemia
• Hypoalbuminemia
• Ammonium biruate crystalluria or urolithiasis
• Elevated blood ammonia concentration
• Increased clotting time
• Elevated hepatic enzyme levels

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Which of those abnormalities is considered tests
of liver function?

• Low BUN
• Hypoglycemia
• Hypoalbuminemia

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Which would be important to you as a surgeon?

• Increased clotting time

14
List 3 components of persumptive diagnosis of
PSS.

• Signalment young animal, breed with high
  incidence, clinical signs
• Biochemical abnormalities
• Plain radiographs showing microhepatica

15
What are the 3 methods of definitive diagnosis of
PSS?

• Doppler flow ultrasonography
• Positive contrast portography
• Liver isotope scan

16
How does ligation of the PSS improve hepatic
function?

• Increases blood flow to the liver
• Increase delivery of hepatotrophic factors from
  splanchnic circulation to stimulate regeneration
  of hepatic tissue

17
Describe the pre-operative management of the
patient with PSS.

• Pre-op
• Low protein diet, oral lactulose, oral neomycin,
  metronidazole or ampicillin
• Control of seizure activity IV dextrose if
  hypoglycemic, phenobarbital

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Why is lactulose used in these patients?

• Binds ammonia decreasing hepatic encephalopathy

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Why is complete ligation of the PSS not always
possible?

• Complete ligation will cause an increase in the
  blood flow to the intrahepatic vasculature which
  may not be adequate and may result in elevated
  portal pressure and the development of multiple
  acquired extrahepatic shunts.

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What are the possible consequences of creating
portal hypertension by ligation of a PSS?

• Development of multiple acquired extrahepatic
  shunts

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Why would gradual occlusion of PSS be desirable?

• If the shunt is occluded gradually, the liver may
  be able to develop more vascular capacity

22
What are 2 methods of achieving gradual occlusion
that are currently used in small animals?

• Use of the ameroid constrictor
• Cellophane banding

23
What are the signs of severe portal hypertension
in the postoperative period?

• Abdominal pain and ileus
• Hemorrhagic diarrhea
• Metabolic acidosis
• Endotoxemia and cardiovascular collapse

24
After which surgical technique is this most
likely to occur? What is the treatment?

• Complete ligation of the shunt or
• Use of the thrombogenic intravascular coil
• Go back in and remove the ligatures

25
Describe postoperative management of a patient
with PSS that does not have severe portal
hypertension.

• Maintain low protein diet
• Monitor for seizure activity (seizures that begin
  in post-op period carry poor px control with
  phenobarb or propofol)
• Longterm
• Maintain low protein diet for 30 to 60days
• Repeat lvr fxn tests at 30 days post sx
• If bile acid levels are normal, increase protein
  in diet
• Some will be maintained on low protein diet for
  life

26
What is the prognosis for dogs with PSS? Is the
prognosis the same for cats?

• Dogs
• Good w/ complete attenuation or ameroid
  constrictor attenuation
• Fair to good w/ partial attenuation
• Guarded w/ development of multiiple extrahepatic
  shunts related to microvascular dysplasia in
  liver
• Cats
• W/ extrahepatic shunts less good than in dogs
• Short term very high incidence of complications
  
• Long term 75 of surviving cats have excellent
  resluts w/ ameroid constrictors, fewer do well w/
  ligation

27
Why is a liver biopsy taken during surgery to
correct PSS?

• To check the microvasculature