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Tobias ECVS > Ch 96 - Hepatic Vascular Anomalies > Flashcards

Ch 96 - Hepatic Vascular Anomalies Flashcards

1
Q

List the tributaries of the portal vein from caudal to cranial

A
  • Mesenteric veins (drain the intestines and form the cranial mesenteric vein)
  • Caudal mesenteric vein
  • Splenic vein (with left gastric vein)
  • Gastroduodenal vein (dogs)
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2
Q

How many hepatic veins do dogs usually have?
Which is the largest?

A
  • 5-8 hepatic veins
  • The left hepatic vein is the largest and most cranial
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3
Q

What embryonic vessels give rise to:
- The hepatic sinusoids
- Hepatic portion of the vena cava
- Portain vein

A

The vitelline vessels

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4
Q

What is the ductus venosus?

A

A venous shunt between the left umbilical vein and the cranial segment of the right vitelline vein (which become the hepatic vena cava)

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5
Q

What shunts most likely arise from patency of the ductus venosus?
- When is functional and structural closure expected?
- In which breed can this be delayed?

A

Left-sided intrahepatic PSS
- Functional closure within 2-6 days after birth
- Structural closure within 3 weeks after brith
- Delayed in Irish Wolfhounds - 23% still open at 6 days but all close by 9 days

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6
Q

What substances promote ductus venosus closure?
What substances slow it down?

A
  • Promote: Endothelin, cytochrome P-450, thromboxane A2
  • Slows down: Prostaglandin F1alpha, PG-E2 - cause relaxtion of the vessel, modulating the effects of endothelin
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7
Q

What are the three broad categories of hepatic vascular disease?

A
  • Congenital PSS
  • Disorders assoc with abnormal hepatic bloodflow or portal hypertension “primary hypoplasia of the portal vein” PVH
  • Disturbances in portal outflow
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8
Q

What % of congenital PSS are extrahepatic?

A

66-75%

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9
Q

Where do acquired shunts most commonly enter the systemic circulation?
What are some causes of acquired shunts?

A

At the renal vein or the vena cava near the renal vein
Causes:
- Hepatic fibrosis
- PVH with portal hypertension
- Hepatic AV malformations

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10
Q

What % of dogs and cats with PVH-MVD have a concurrent congenital PSS?

A
  • Dogs 58%
  • Cats 87%
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11
Q

What breeds are overrepresented for PVH-MVD?

A

Cairn terrier, Maltese, Yorkie

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12
Q

How much liver function needs to be lost for hepatic encephalopathy to occur?

A

70%

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13
Q

List the various toxins inplicated in hepatic encephalopathy and their mechanisms

A
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14
Q

What usually happens to ammonia in the liver?

A

Converted to urea and glutamine in the urea cycle

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15
Q

What breeds are predisposed to exhepatic PSS?

A

Yorkies, Norweigan Terrier, Havanese, Maltese, Dandie Dinmont Terrier, Pugs, Min Schnauzer

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16
Q

What genes have been detected to have an increased expression in intrahepatic and extrahepatic shunts?

A
  • Intra: WEE1
  • Extra: VCAM1
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17
Q

What breed is represented for PVH-MVD accounting for 27% of cases?

A

Doberman

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18
Q

What changes may be seen on biochemistry with a PSS?

A
  • Hypoalbuminaemia (50%)
  • Reduced BUN (70%)
  • Leucocytosis (poorer prognosis)
  • Mild-to-mod elevation of liver enz
  • Creatinine often decreased
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19
Q

What percentage of dogs and cats with a congenital PSS will have ammonium biurate crystalluria?

A

26-57% dogs
16-42% cats

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20
Q

What dogs may have elevated bile acid concentrations with no hepatic dysfunction?

A

Maltese

21
Q

What is the sensitivity of the ammonia tolerance test for hepatic insufficiency?

A

95-100%

22
Q

What is the protein C activity in normal dogs?
With PSS?
With PVH-MVD?

A
  • Normal: 70%
  • PSS: 88% have levels below 70%
  • PVH-MVD: 95% have levels above 70%
23
Q

What is the normal portal velocity of dogs?

A

15cm/s
- Icreases of variable in 53% of extrahepatic and 92% of intrahepatic PSS

24
Q

What is the specificity and sensitivity of transsplenic scintigraphy fo diagnosis of congenital PSS?
What nucleotides are used?

A
  • 100% sensitive and specific!
  • Technitium-99m pertechnetate or mebrofenin
25
Q

What is the role of lactulose in medical management?

A
  • Promotes acidification of colonic contents, resulting in entrapment of luminla ammonia
  • Decrease in colonic bacterial numbers
  • Osmotic effect reduces faecal transit time
26
Q

What was the MST of 27 medically managed dogs vs 99 surgically managed?

A
  • Medical: MST 2.3yr
  • Surgical: 78% still alive at 6yr
27
Q

How much plasma is required to increase albumin by 1g/dL?

A

45ml/kg

28
Q

What options are there if you cannot find the shunt vessel in surgery?

A
  • Intraop mesenteric portovenography
  • Portal catheterisation
  • Intra-op Doppler ultrasound
29
Q

What is a normal baseline portal pressure?

A

8-13cmH2O (6-10mmHg)

30
Q

What is the maximum amount of contrast that can be used during mesenteric portovenography?

A

1200mg iodine/kg
Overdose - hypotension, arrhythmias, cardiac arrest, renal failure

31
Q

List options for surgical occlusion of shunts

A
  • Ameroid constrictor (inner casein sheath expands to decrease inner diameter by 32%
  • Cellophane banding
  • Hydraulic occluders
  • Suture ligation (partial or complete) with 2-0 silk in dogs, polypylene in cats (can have recanalisation wtih silk)
32
Q

What portal pressure measurements can help to determine amount of shunt attenuation which will be tolerated?

A
  • Max portal pressure 17-24cmH2O (12.5-17.6mmHg)
  • Maximum change of 9-10cmH2O (6.6-7.35)
  • Maximum decreased in central venous pressure of 1cmH2O
  • Decrease in arterial pressure of a maximum of 5mmHg or 15%
  • HR should not dramatically increase
33
Q

In what % of dogs does liver function return to normal after a single partial ligation?

A

70%

34
Q

What are the broad options of treatment of an intrahepatic shunt?

A
  • Extravascular ligation (usually of shunt or draining hepatic vein, occassionally of feeding portal branch)
  • Intravascular ligation (not really one anymore)
  • Intravascular coiling
35
Q

What are the reported post-op complications?

A
  • Hypogylcaemia 44%, 29% of which are refractory to dextrose
  • Haemorrhage and anaemia
  • Portal hypertension 2-14% with acute ligation
  • Seizures and encephalopathy 3-18% dogs, 8-22% cats
36
Q

What other derangement can occur with post-op hypoalbuminaemia?

A

Hyponatraemia - cause unknown

37
Q

What are potential causes of recurrence or persistence of clinical signs post-attenuation?

A
  • Continued flow through original shunt
  • Presence of a second shunt
  • Multiple acquired shunts
  • Congenital PVD
  • Unrelated disease
38
Q

What are the reported periop mortality rates for extrahepatic PSS?

Intrahepatic?

A

Extrahepatic:
- Suture: 2-32%
- Ameroid: 7%
- Cellophane: 6-9%
- Good-to-excellent outcome in 78-94%

Intrahepatic:
- Suture: 6-23%
- Ameroid: 0-9%
- Cellophane: 27%
- Probability of long term survival withou recurrence 60-61% at 1yr, 55-56% at 2-4yr

39
Q

What values on pre-op bloodwork may be associated with survival?

A
  • Anaemia - poorer long-term outcome
  • Increased BUN assoc with a decreased short-term survival
  • Increased WBC/neutrophils assoc with decreased survival and unsuccessful long-term outome
  • Higher pre-op albumin and TP assoc with better short term survive for intrahepatic PSS
  • Extrahepatic ameroid: for every decreased in albumin by 1g/dL, odds of continued shunting increased 3.76 times. For every increase of albumin by 1, odds of unsuccessful outcome decreased by 0.4times
40
Q

What is the perioperative mortality and prognosis in cats?

A
  • Ameroid: 0-4.5% mortality
  • Cellophane: 0-22%
  • Suture: 4-20%

Good-to-excellent outcome in:
- Ameroid: 33-75%
- Cellophane: 57-80%
- Suture: 56-75%

Generalised seizures in 8-28% and central blindness in up to 44% (usually resolves within 2 months)

41
Q

What % of dogs will have AV malformations in 2 lobes?

A

20%

42
Q

What pertreatment is required prior to ligation of hepativ AV malformation?

A

Pretreatment with atropine or glycopyrrolate to prevent reflex bradycardia (Branham reflex)

43
Q

What is the prognosis for hepatic AV malformations?

A
  • Perioperative survival 75-91%
  • Long-term outcome fair or good in 38-57%
  • 75% continue to require dietary or medical management (continue to have multiple acquired shunts)
44
Q

What introducing vessel is used for intrahepatic and amenable extrahepatic shunts and for AV malformation during interventistic procedures?

A
  • PSS: Jugular vein
  • AV malformations: femoral artery
45
Q

What is the goal in regards to portal pressures for intravascular coiling?

A
  • Increase the portal pressure by 7mmHg, but not higher than a final portal pressure of 15mmHg
  • Coils are added until the mouth of the shunt is covered or the portal pressure is no greater than 10cmH2O (7mmHg) above baseline or a final pressure of approx 20cmH2O (15mmHg)
46
Q

What kind of stent is used as a caval stent during intravascular coiling?

A

Laser-cut, self-explandin, nitinol stent

47
Q

What medication should patients with intrahepatic shunts recieve for the rest of their lives?

A

Omeprazole to reduce the risk of GI ulceration
- With addition of lifelong antacids, mortality dropped from 25% to 3.2%

48
Q

What can be added to cyanoacrylate glue to aid with embolisation procedures?

A
  • 1:1 or 1:2 ratio with Ethiodol - makes mixture radioopaque and slows polymerisation
  • Powdered tantalum - additional radioopacity

Tobias ECVS (110 decks)

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