Liver, biliary tract and portosystemic shunts Flashcards
Discuss indications for liver surgery?
Most commonly biopsy
- Part of routine screen
- Mass
- Generalised hepatopathy
- Hepatitis
- Jaundice
- Etc.
Less commonly to remove primary hepatic tumour
What is a portosystemic shunt?
Anomalous connection between the portal and systemic venous systems
Discuss bypassing the liver circulation in development?
Bypass of the liver
- Normal in utero (ductus venosus)
Abnormal post partum
- Persistent (patent) ductus venosus ( it should close and become a ligament)
- Intrahepatic
- Extrahepatic Portosystemic shunts (PSSs)
Which types of dogs are likely to get intra-hepatic and extra-hepatic portosystemic shunts?
Large breed dogs most commonly get intrahepatic shunts
Small breed dogs most commonly get extrahepatic shunts
Discuss portal vein hypoplasia - microvascular dysplasia (PVH-MVD)?
- Microscopic shunting within the liver itself.
- Shunting of portal blood into systemic venous drainage of liver at the microscopic level of the liver as well.
- Unfortunately small breeds listed above may have extrahepatic as well as microvascular shunt.
Causes:
- Abnormal hepatic blood flow
- Communication between portal and systemic circulation at microvascular level.
- Occur concurrenty with PSS in 58% dogs and 87% cats.
- Cairn and Yorksire terriers prone to it
What are the histological findings of PVH-MVD?
Small intrahepatic portal vessels
What are the clinical signs of portosystemic shunt?
in the following categories: neurological, GI, urinary
Neurologic
- Lethargy
- ataxia
- obtundation
- pacing
- circling
- blindness
- seizures
- coma
Gastrointestinal
- Vomiting
- diarrhoea
- anorexia
- pica
- melaena
- haematemesis
Urinary
- Haematuria
- stranguria
- pollakiuria
- urethral obstruction
Take much longer to wake up from anaesthetic as the liver does not metabolise the drugs very quickly
How does lactulose treatment work for HE?
- Lactulose is used to manage hepatic encephalopathy.
- Binds ammonia and reduces the toxin in blood stream and reduces neurological signs.
- The ammonia is bound to it in the bowel before it gets absorbed into the blood stream.
- It does make the animal defecate more frequently and however this also lowers the bacterial load which can increase uptake of ammonia as well so works in 2 ways.
Discuss surgical ligatino of a PSS?
What material?
- Polyprolene(non- reactive)
- Silk (reactive)
Complete attenuation
- 50-86% can not tolerate
Partial attenuation
- Second surgical 3-6 months later
Discuss blood pressure when ligating PSS?
When you completely ligate straight away BP goes up too high whereas attenuated material closes slowly over time and keeps BP more manageable and allows body to adjust.
What is happening here?
Contrast media being injected for fluroscopy to indentify the type of shunt present.
What is occuring here?
Fluoroscopy
- Intraoperative mesenteric portography (IOMP)
- Digital subtraction
- Pre-and post temporary ligation images
- Portal pressure measurement?
- PSSs –surgical treatment
What kind of shunt can be seen here?
Extra hepatic shunt going into phrenic vein
What kind of shunt can be seen here?
Spleno-caval shunt
What kind of shunt can be seen here?
Azygous vein shunt
Discuss the ameroid ring for surgical treatment of PSS?
Ameroid ring
- Ring of casein surrounded by stainless steel
- Hygroscopic substance that swells after absorbing fluid
- Incites a fibrous tissue reaction
- Constricts slowly over time causing a gradual closure of the BV.
Discuss cellophane banding for treatment of portosystemic shunt?
Cellophane banding
- Clear non-medical grade cellophane
- 3-or 4-ply strips sterilised using EO
- Titanium clips used to hold in place
- Fibrous tissue reaction leading to gradual occlusion
Discuss intrahepatic shunt surgery methods?
Percutaneous transvenous coil embolisation
- Fluorsoscopic guidance
- Caval stent placed via jugular vein
- Embolisation coils inserted through a vascular catheter
- Can be done in open surgery by dissecting down the liver but can be done intrahepatically by method outline above.
- The multiple coils (pic) produces a clot and leads to coil embolisation.
- Often these dogs need further surgery as it doesn’t work straight away.
What is this?
transvenous coil embolisation
Indications for cholecystectomy are stated to include:
- Ruptured gallbladder
- Primary neoplasia of the gallbladder
- Cholecystitis that is unresponsive to medical management
- Gallbladder mucocoele
- Cholelithiasis
What can be seen here?
Biliary tract –traumatic rupture
- Causes a sterile peritonitis
- And the bile is not being recirculated and the animal will become jaundice as a result
- Can present acutely but commonly present a few days after traumatic rupture.
- Bile is chemically an unpleasant material and suturing it is hard as it cause dehescence so gall bladder removal is indicated.
What is this?
- Biliary tract –primary neoplasia
- Rarely see primay neoplasia and most likely be a malignancy from a carcinoma
What is this?
Cholecystitis/cholelithiasis
- Don’t often see these and if we do often picked up incidentally
- perhaps animal has chronic low grade choleocystitis (gall Stones) feel pretty rotten it can wax and wane the pain and they hide it well.
What is this?
Gall bladder mucocoele
- Caused by stasis of bile material and the water is drawn out of it creating this solid green sludge.
- Border terriers seem to be prone to it.
- Clinical signs variable. Often don’t have jaundice as they arent obstructed but they have a distended painful gall bladder.
- Imaging can detect this finding. Treatment of choice choliocystectomy.
Indications for permanent biliary bypass include the following:
Any underlying disease that has led to permanent and complete obstruction of the bile duct, major duodenal papilla or proximal duodenum
Where resection of the proximal duodenum including the bile duct is required
Common causes include:
- Cholelithiasis
- Neoplasia of bile duct, pancreas or duodenum
- Pancreatitis (rarely)
- Permanent biliary bypass
What is occuring here?
Endoscopic retrograde cholangio-pancreatography(ERCP)
What is occuring here?
Choledochal stenting
- In SA the the stent is place via open surgery not endoscopy
- Stitched in with dissolvable suture material so it is in place for a week and then is passed.
What’s occuring here?
- Islet cell tumour within pancreas which is overproducing insulin.
- Lots of endocrine tumours are very small but have a dramatic effect because of the hormones they produce.
- Islet cell tumour treated via pancreotomy of either left or right limb of the pancreas. Left limb easier to remove as right limb has a BS to the associated duodenum.
What can be seen here?
Insulinoma
What does the blood supply to the spleen look like?
Discuss mass ligation of spleen in emergency?
Discuss total splenectomy?
- In humans a total splenectomy would cause low WBC and a reduced ability to fight infection this doesn’t happen in animals so you can do a total splenectomy in animals.
- The carefully ligation procedure of each vessel pictured is not for emergency but is more carefully done and maintains bloody supply to stomach.
- Advanced bipolar electrocautery devices making it even easier now as can do it sutureless.
