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Surgery > E2- Portosystemic shunt > Flashcards

E2- Portosystemic shunt Flashcards

1
Q

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 = ________

A

portosystemic shunt

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2
Q

Extrahepatic PSS signlament

A

small dogs and cats

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

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3
Q

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

A

portal vein

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4
Q

What 2 veins are most commonly involved in extrahepatic shunts?

A

left gastric vein and splenic (gastrosplenic)

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5
Q

What veins are less commonly involved extrahepatic shunts?

A

direct portocaval

gastroduodenal

mesenteric (jejunal and colic veins)

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6
Q

IIntrahepatic PSS signalment

A

Large breeds

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

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7
Q

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

A

hepatic parenchyma

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8
Q

What is portal vein atresia?

A

portal vein never developed

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9
Q

portal vein atresia affects what vessels?

A

major pre-hepatic vessels

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10
Q

Ascites is more common in what type of shunt?

A

portal vein atresia

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11
Q

T/F: acsites is hyperproteinemia

A

FALSE- hypoproteinemia

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12
Q

_____ occurs when shunt is partially occluded. Why?

A

Portal hypertension

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

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13
Q

Portal vein atresia treatment

A

medical management

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14
Q

Portal vein hypoplasia (PVH) is hepatic _____ dysplasia

A

microvascular

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15
Q

Portal vein hypoplasia- ______shunting w/in the liver

A

microvascular

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16
Q

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

A

macrovascular shunts

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17
Q

Portal vein hypoplasia clinical signs

A

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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18
Q

Laboratory tests for Portal vein hypoplasia

A
  • 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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19
Q

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

A

PSS (>70%)

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20
Q

Treatment of stable form of portal vein hypoplasia

A

none- just need to know its there

medical management- diet is often enough

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21
Q

Treatment of progressive form of portal vein hypoplasia

A

(extensive liver involvement)

pathophysiology similar to uncorrected macrovascular shunts

diet- restrict protein levels

medical management

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22
Q

Multiple extrahepatic PSS is secondary to diseases the cause _______

A

portal hypertension

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23
Q

Multiple extrahepatic PSS secondary to ______ shunt ligation

A

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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24
Q

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

A

true

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25
Q

2 examples of non-cirrhotic portal hypertension

A

idiopathic portal hypertension

hepatic veno-occlusive dz

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26
Q

______ can open up preventing lethal portal hypertension from developing

A

vestigial embryonic communications

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27
Q

Macrovascular shunt diagnosis

A

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

28
Q

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

A

CT angiography

portography if P is open

29
Q

Macrovascular shunt general signs

A

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

30
Q

Macrovascular shunt nervous system signs

A

toxins not being taken out by liver

lethargy, depression, weakness, behavior, pacing, aggression, ataxia, stupor, head pressing, coma, seizures

31
Q

Macrovascular shunt GI signs

A

anorexia, vomiting, diarrhea, ptyalism, pica, ascites

32
Q

Macrovascular shunt urinary system signs

A

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

33
Q

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

A

Macrovascular shunt

34
Q

Acsites is uncommon with congenital PSS unless severely ______

A

hypoproteinemic (poor prognostic sign)

severe portal vein hypoplasia, portal vein atresia

35
Q

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

A

<70% macro

>70% micro

36
Q

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

A

<100 micro

>100 macro

37
Q

Urinalysis on a animal with macrovascular shunt

A

ammonium biurate crystals- like seen in dalmations

multiple UAs may be necessary

38
Q

US for macrovascular shunts

A

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

39
Q

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

A

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

40
Q

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

A

CT angiography- noninvasive

most diagnostic

41
Q

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

A

Portography- invasive mesenteric vein injection

42
Q

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

A

FALSE- Portography not necessary if preop CT angiography performed

43
Q

What is the suggested medical treatment for macrovascular shunts?

A

diet- protein restricted

lactulose

antimicrobials

sz control/prevention

control intestinal parasite

44
Q

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

A

if less than 1.5mg/dl - surgery is much riskier

45
Q

Explain what the goal of surgical intervention is

A

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

46
Q

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

A

epiploic foramen

ometal bursa

esophageal hiatus

47
Q

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

A

Ligation

possible in <1/2 cases

48
Q

_______- vessel is partially occluded

A

attenuation

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

49
Q

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

A

9-10 cm H2O

we dont want it to go over 10

50
Q

Ameroid constrictor reasons for acute complications?

A

rapid closure, kinking

51
Q

Ameroid constrictor- chronic complications

A

incomplete occlusion

acquired shunts (~20% of cases)

implant migration- just the ring itself probably not be a problem

52
Q

With cellophane banding, occlusion is entirely by ______

A

inflam rxn

53
Q

Cellophane banding typically occludes completely within _____

A

8-12 days if occluded to <3mm

if larger takes longer

variable results in cats

54
Q

Advantages hydraulic occluders

A

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

55
Q

Disadvantages hydraulic occluders

A

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

56
Q

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

A

pre-hepatic

post-hepatic

57
Q

Intravascular occlusion includes what 3 types?

A

intracaval

transportal

thrombogenic coils

58
Q

List acute post-op complications with shunt sx

A

portal hypertension

portal vein thrombosis

hypoglycemia

szs- 4-6% incidence in patients with no prior history

hemorrhage

electrolyte disturbances- hyponatremia often iatrogenic

59
Q

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

A

until they are recovered from anesthesia

60
Q

T/F after shunt sx we want to withhold food

A

FALSE- encourage early food intake

61
Q

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

A

for signs of hypertension

62
Q

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

A

True- eyelid twitching frequent prodromal sign

63
Q

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

A

4-8 weeks minimum

routine bloodwork

liver function test- goal is to get them normalized! protein C activity

64
Q

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

A

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

65
Q

Long term outcome of extrahepatic shunt sx?

A

good to excellent 78-94%

66
Q

Long term outcome for intrahepatic shunt sx?

A

good to excellent 50-89%

67
Q

What is the prognosis of shunt surgery for cats?

A

75% post op complications

good to excellent outcome- 30-80%

Surgery (15 decks)

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