Lecture 15: Surgery of the Liver (Exam 3)

Question 1

Define hepatectomy

Answer 1

Removal of the entire liver

Question 2

Define partial hepatectomy

Answer 2

Removal of a portion of the liver

Question 3

Define lobectomy

Answer 3

Often used to refer to the removal of a single (or multiple) liver lobes w/out perform a total hepatectomy

Question 4

What are the preop concerns

Answer 4

• Hypoalbuminemia (below 2g/dl)
• Coagulopathies
• Anemia
• K+ abnorms
• Anorexia
• Hypoglycemia
• Massive ascites (lots of fluid in the stomach)

Question 5

What type of bacteria normally reside in the liver

Answer 5

Aerobic & anaerobic

Question 6

When are ax used in liver sx

Answer 6

Px w/ severe hepatic dx that are undergoing hepatic surgery

Question 7

What are the two afferent blood supplies

Answer 7

• Portal system (low pressure)
• Arterial system (high pressure)

Question 8

Describe the portal vein in the liver

Answer 8

• Drains the stomach, intestines, pancreas, & spleen
• Supplies 4/5ths of the blood that enters the liver

Question 9

Describe the proper hepatic arteries

Answer 9

• Provides the remainder of the afferent blood supply
• These are branches of the common hepatic artery may # btw/ two & five

Question 10

When dissecting around the pylorus what should be avoided

Answer 10

Damaging the common bile duct

Question 11

What are the diff types of liver biopsy techs

Answer 11

• Percutaneous & fine needle (blind & ultrasound guided)
• Laparoscopic
• Guillotine method
• Punch
• Partial lobectomy

Question 12

How is tissue core biopsies obtained in percutaneous bx

Answer 12

• Tru cut biopsy
• Large bore needle
• Automated bx device

Question 13

Who should automated bx device not be used on & why

Answer 13

Cats b/c of the potential mortality associated with/ the shock wave caused by triggering the device

Question 14

Where are percutaneous core bx performed on the liver & why

Answer 14

• Left lateral lobe
• Min the chance of lacerating the bile ducts or gallbladder (both are on the right side)

Question 15

Why is taking bx only on the left lateral lobe a significant limitation

Answer 15

B/c lesions may be present in only a few of the liver lobes

Question 16

What is a disadvantage of percutaneous liver bx

Answer 16

False neg results are far more common than false positive results

Question 17

Summarize the guillotine liver bx method

Answer 17

• Place a loop of suture around the margin of a liver lobe
• Pull the ligature tight so it crushes through the hepatic parenchyma before tying it
• Use a blade to take out the mass

Question 18

Summarize a punch biopsy

Answer 18

• Hemostatic foam
• 6mm min
• Bx where norm & abnorm meet

Question 19

Summarize a partial lobectomy

Answer 19

• Make a line of separation btw/ norm & what has to be removed
• Incise the liver capsule along the site
• Bluntly fracture the liver & expose the parenchymal vessels
• Ligate large vessels & electrocoagulate small bleeders

Question 20

What are portosystemic vascular anomalies (Portosystemic shunts) & Give a specific example

Answer 20

• Allow norm portal blood draining to pass directly into the systemic circulation w/out first passing through the liver
• Portocaval shunts are a specific vascular anomaly (portal vein to caudal vena cava)

Question 21

What are extrahepatic shunts

Answer 21

• Vascular anomalies located outside the hepatic parenchyma
• Can be congenital extrahepatic portosystemic shunts (CEPSSs) or acquired

Question 22

Where are congenital intrahepatic portosystemic shunts (IHPSSs) located

Answer 22

In the liver

Question 23

What is hepatic microvascular dysplasia (HMD)

Answer 23

Small or absent intrahepatic portal vessels & portal arteriolar hyperplasia associated w/ microscopic shunting of blood through the liver w/out a macroscopic portosystemic shunt

Question 24

What are the broad general categories of shunts

Answer 24

• Congenital or acquired
• Intrahepatic or extrahepatic

Question 25

Describe congenital extrahepatic shunts

Answer 25

* Single anomalous vessels that allows abnormal blood from the portal vein directly to the systemic circulation * Accounts for nearly 63% of single shunts in dogs * Also occurs in cats * Usually small thin dogs

Question 26

Describe congenital extrahepatic shunts in cats

Answer 26

Large single vessel that empties directly into the pre hepatic vena cava

Question 27

Describe intrahepatic portosystemic shunts

Answer 27

* Usually congenital (35% of single shunts in dogs) * Singular shunts that occur b/c the ductus venosus fails to close after birth * May arise when other portal to hepatic vein or caudal vena cava anastomoses exist

Question 28

What is most commonly associated with/ multi extra hepatic shunts

Answer 28

Chronic severe hepatic dx (not surgical candidates)

Question 29

T/F: HMD is surgical

Answer 29

False it is nonsurgical

Question 30

What types of shunts are small breed & large breed dogs more likely to have

Answer 30

* Small: extrahepatic shunts * Large: IHPSSs

Question 31

When should congenital PSS be considered in young animals

Answer 31

When there is prolonged response to ax agents or tranquilizers that require hepatic metabolism for clearance

Question 32

Describe nuclear scintigraphy

Answer 32

A useful noninvasive screening tool for dxing congenital or acquired shunts to distinguishes them from HMD

Question 33

Describe the medical management for the liver

Answer 33

* Surgery appears to be the tx of choice * Medical management of px w/ congenital PSS has a mortality rate of 48%

Question 34

What is the surgical tx of PSSs

Answer 34

* Only px w/ congenital PSS are surgical candidates * Goal: is to ID & occlude (acutely cut off circulation) or attenuate (slowly over time cut off circulation) the abnormal vessels

Question 35

What are the three methods of surgical occlusion or attenuation in PSSs

Answer 35

* Ameroid constrictor * Cellophane banding * Ligation

Question 36

What is this

Answer 36

Ameroid ring

Question 37

What does cellophane banding cause

Answer 37

* Initial acute inflammatory response * Chronic low grade foreign body tissue reaction

Question 38

Why can ligation be fatal

Answer 38

Often leads to portal hypertension which may be fatal

Question 39

What is good to know about sx options

Answer 39

* If multi shunts be sure to bx the liver * Ameroid should fit on the vessel w/out compromising the lumen * Avoid using too large of an ameroid b/c the weigh ot the device may cause the vessel to kink (obstruct flow prematurely) * Warn owners that ligation of IHPSS is difficult b/c the shunts are often hard to ID @ sx

Question 40

What are cavitary hepatic lesions

Answer 40

Usually cysts or abscesses

Question 41

What are hepatic abscesses

Answer 41

Localized collections of pus in the hepatic parenchyma

Question 42

What are hepatic cysts

Answer 42

Closed fluid filled sacs lined by secretory epithelium

Question 43

What is the sx procedures for cavitary hepatic lesions

Answer 43

* Generally by partial hepatectomy * Omentalized

Question 44

Describe omentalization

Answer 44

* ID a segment of the omentum that will extend into the cyst cavity * Remove as much of the wall of the cyst as possible * Spread the omentum over the remaining cyst & adjacent liver * Tack it gently in place to the remaining cyst capsule

Question 45

Describe hepatic lobe torsion

Answer 45

* Occurs when a liver lobe twists around it axis * Rare in dogs & cats * Torsion of the left lateral or medial appear to be the most common * Cause is unknown (congenital failure or rupture of the hepatic lig)

Question 46

What occurs b/c of a hepatic lobe torsion

Answer 46

* Venous obstruction * Increased hydrostatic pressure * Ascites * Thrombosis * Lobe will eventually necrose