Liver Vascular Malformations Flashcards
The liver receives 20% of its blood supply from A) the - a branch of the B).
A) Hepatic a.
B) Coeliac a.
The hepatic artery branches at the porta of the liver to supply each lobe. This is under A) pressure. The other 80% of blood comes from the B) which entirely drains the gastrointestinal (GI) tract (from stomach to cranial rectum), pancreas and spleen.
A) High
B) Low pressure portal vein
What is the normal direction of the blood supply in the portal vein?
Towards the liver (hepatopetal)
In the absence of valves in larger vessels; which direction does blood travel? (pressure)
High –> Low
Where does the left phrenic vein drain blood from and into?
diaphragm into the caudal vena cava
Define portosystemic shunt
An anomalous vessel which allows blood to bypass some, or all, of the liver
What is the difference between intra and extra PSS?
Portosystemic shunts can occur inside the liver parenchyma (intra-hepatic) or outside of the liver parenchyma (extra-hepatic)
Generally PSS are what type in small breeds?
Extra hepatic
Generally PSS are what type in large breeds?
Intra hepatic
Most common breed type for PSS?
Toy/miniature
What age do patients tend to present with PSS?
1-2 yr
What do acquired PSS tend to happen as a result of?
Severe chronic hepatic dx
How does an acquired PSS develop?
Non-functional connections exist in the foetus and will remain quiet in the adult unless chronic portal hypertension develops
How many shunts are common with acquired?
Multiple
T or F:
Surgery is indicated for acquired PSS?
False
How many shunts are common with congenital PSS?
Commonly 1
How are congenital intra hepatic shunts be classified?
Right
Central
Left
What do all 3 types of intra hepatic PSS connect the intra-hepatic portal system to?
Vena cava
What are the 4 classifications of extra heptatic PSS that 94% can be classified as?
Spleno-caval
Left gastro-phrenic
Left gastro-azygous
Right gastric vein based shunts.
In the spleno-caval shunt, where is the shunt?
From part of the left gastric vein, near the splenic vein - the blood is diverted straight into the caudal vena cava, from a more central part of the left gastric vein
(the shunting vessel is not actually direct from the splenic vein to the caudal vena cava.)
What is the anatomy of a gastro-phrenic EHPSS?
Connection of the L gastric –> L phrenis –> Caudal VC
At which anatomical landmark do you think a right gastric vein-based shunt enters the caudal vena cava?
Epiploic foramen
What happens with a R gastric bein EHPSS
A right gastric vein-based shunt has a connection to the caudal vena cava in the same location as the spleno-caval shunt, but the direction of blood flow and development of shunting leads to a distended right gastric vein
The azygous vein runs as a parallel system to the caudal vena cava, draining blood from the ?
vertebrae
The azygous vein passes through the A) and ends at B) with the vena cava
A) aortic hiatus
B) right atrium
What happens with a left gastro-azygous EHPSS?
The shunting vessel joins the azygous vein in the thoracic cavity. It goes through the aortic hiatus to get there.
The small phrenicoabdominal veins enter the caudal vena cava approximately 1cm cranially to the renal veins. Moving cranially, there should be no further vessels entering the vena cava until you reach the ? Any vessels in-between can be considered anomalous.
hepatic veins.
Common signs of a PSS? (6)
Hepatic encephalopathy (HE) – present in the majority of affected dogs
Chronic gastrointestinal signs – anorexia, vomiting
Lower urinary tract signs associated with urate urolithiasis in 40% of cases
Retarded growth, weight loss
Ptyalism and central blindness in cats
Polyuria/polydipsia
Common findings on CE with PSS? (3)
Microhepatica (more common in dogs than cats)
Prominent kidneys
Copper coloured iris in cats.
Finding on haematology with PSS? (2)
Mild to moderate, microcytic, normochromic nonregenerative anaemia
Leucocytosis
Findings on coag profile with PSS?
Are usually normal but dogs with PSS may have prolonged APTT
Biochem findings with PSS? (8)
Bile acids (fasting and post prandial) – elevated
Ammonia (where available) – elevated
Hypoalbuminaemia (50% of dogs, less common in cats)
Decreased BUN (70%)
Hypocholesterolaemia
Hypoglycaemia
Mild to moderate increase in liver enzymes (e.g. ALT)
Protein C activity is a sensitive test for liver insufficiency and is usually lower in dogs with a PSS.
Post-prandial bile acids are typically what with PSS?
> 100 µmol/L
why is a decreased BUN seen with PSS?
Reduced conversion to ammonia to urea and PUPD seen in many patients
What are bilirubin levels in PSS?
Often normal