HPB Flashcards
1
Q
How does pancreas divisum occur?
A
- Failure of the dorsal and ventral buds to fuse.
- In utero, the majority of the pancreas is drained by the dorsal duct which opens up into the minor papilla.
- The ventral duct drains the minority of the pancreas and opens into the major papilla.
- In adults however, this situation is reversed whereby 70% of the pancreas is drained by the ventral duct.
- Therefore in pancreas divisum, where fusion of the ducts does not occur, the major drainage of the pancreas is done by the dorsal duct which opens up into the minor papilla.
- The high ductal pressure may result in recurrent pancreatitis (large duct but small opening).
2
Q
What are the subtypes of pancreas divisum?
A
3 subtypes
- type 1 (classic): no connection at all; occurs in the majority of cases: 70%
- type 2 (absent ventral duct): minor papilla drains all of pancreas
- type 3 (functional): filamentous or inadequate connection between dorsal and ventral ducts: 5-6%
3
Q
what is the blood supply to the pancreas?
A
Arterial
- mainly from the splenic artery via one of its largest branches known as the arteria pancreatica magna.
- head is supplied by the superior and inferior pancreaticoduodenal arteries (from the gastroduodenal and superior mesenteric arteries, respectively)
Venous
- Venous return is by numerous small veins into the splenic vein, which is formed within the splenorenal ligament and receives the left gastroepiploic vein.
- The head is also drained by the superior and inferior pancreaticoduodenal veins into the portal and superior mesenteric veins, respectively.
4
Q
What are the tributaries of the portal vein?
A
The tributaries of the portal vein are:
- Splenic
- superior mesenteric
- superior pancreaticoduodenal
- Left/right gastric
- cystic
5
Q
What is the blood supply to the CBD?
A
Arteries involved
- Right hepatic
- Retroduodenal (posterior superior pancreaticoduodenal)
- Cystic
- Gastroduodenal
5 % non-axial
- Arising directly from the main trunk of the hepatic artery as it runs parallel to the bile duct
95% of the supply is axial
- derived from the 3 and 9 o’clock vessels which travel along the lateral border of the CBD and form a mesh network
- Inferiorly = 60 % (run upwards)
- retroduodenal (aka posterior superior pancreaticoduodenal)
- Superiorly = 40% (run downwards)
- right hepatic (sometimes common hepatic and rarely left hepatic)
6
Q
What are the variations in the blood supply to the gallbladder?
A
- The cystic artery (CA) usually arises from the right hepatic artery (RHA) in 70% of cases.
- In 20% of cases the CA arises from the common hepatic artery (CHA), its bifurcation or the left hepatic artery.
- In 10% the CA arises from an accessory RHA.
- Occasionally (< 2.5%), it arises from the gastro-duodenal artery (GDA)
7
Q
what is the accessory right hepatic artery and why is it important in HPB surgery?
A
- An accessory RHA arises low from the SMA running through Calot’s triangle posterior and parallel to the cystic duct (8% of patients).
- This can be mistaken for a posterior branch of the cystic artery.
8
Q
what are the variations of the extra-hepatic biliary tree?
A
BLUMGART classification
- TypeA–57% - normal
- Type B – 12% – trifurcation
- TypeC–20%– drainage of a right sectoral duct into the common hepatic duct (C for Common)
- TypeD–6%– drainage of a right sectoral duct into the left hepatic ductal system
- Type E – 3% – no confluence
- Type F – 2% – Rt post sectoral joins cystic duct
9
Q
How is the liver divided into right and left FUNCTIONAL lobes?
A
Cantlie’s line
- An imaginary line which extends from the fundus of the gallbladder to the IVC
- Also is where the middle hepatic vein runs
Falciform ligament
- divides the left lobe into a medial- segment IV and a lateral part - segment II and III.
The FUNCTIONAL lobes of the liver are
- RIGHT = anatomical right lobe, portion of caudate
- LEFT = anatomical left lobe, quadrate lobe and remainder of caudate.
10
Q
How is the liver maintained in position?
A
The liver is maintained in position by being
- (1) joined to the posterior abdominal wall by veins (hepatic and caval) and ligaments (coronary and triangular)
- (2) supported inferiorly by viscera (e.g., the right kidney and colic flexure)
- (3) suspended by ligaments (falciform and teres)
11
Q
What is Couinad classification?
A
- Divides the liver into functionally independent 8 segments
- Each segment has its own vascular inflow, outflow and biliary drainage.
- In the centre of each segment there is a branch of the portal vein, hepatic artery and bile duct.
- In the periphery of each segment there is vascular outflow through the hepatic veins.
Hepatic veins divide liver into sectors
12
Q
What is the anatomy of the portal triad?
A
- The hepatic artery and portal vein, along with the bile duct, are collectively known as the portal triad.
- The portal triad runs within the free edge of the lesser omentum, which also forms the anterior boundary of the epiploic foramen (the entrance to the lesser sac).
- The portal vein lies posterior, the hepatic artery anterior and to the left, and the bile duct anterior to the right.
- Lymphatic vessels and autonomic nerves also run with the portal triad.
13
Q
What is the difference between a “replaced” and “accessory” hepatic artery?
A
Replaced
means that the artery supplying a particular volume of liver is
- in an unusual location
- it is the sole supply to that volume of liver.
Accessory
- ‘Accessory’ refers to an artery which is additional, i.e. is present in addition to the normal structure
- is not the sole supply to a volume.
- Consequently, ligation of an accessory artery does not result in ischaemia.
14
Q
What are the important anatomical variations of the right and left hepatic arteries?
A
Right hepatic artery
- The replaced right hepatic artery arises from the superior mesenteric artery.
- It runs from left to right behind the lower end of the common bile duct to emerge and course on its right posterior border.
- It may supply partially (segment, section) or the entire right hemiliver.
- Rarely, this artery supplies the entire liver and then it is called a replaced hepatic artery.
Left hepatic artery
- arises from the left gastric artery and courses in the lesser omentum in conjunction with vagal branches to the liver (hepatic nerve).
- Supply can be either partial or full to the hemiliver
- Sometimes left hepatic arteries arising from the left gastric artery are actually accessory rather than replaced, and exist in conjunction with normally situated left hepatic arteries.
- Transection of the left gastric artery at its origin during gastrectomy may cause ischaemic necrosis of the left hemiliver if a replaced left artery is present
15
Q
what are the sites of porto-systemic anastomosis?
A
