Liver Vasculature Flashcards
1
Q
What is the largest organ in the human body?
A
The liver.
2
Q
Where does the liver lie?
A
It lies in the intraperitoneal cavity.
3
Q
What does the liver do?
A
- It plays an essential role in all metabolic processes in the body
- It filters and detoxifies the blood and helps regulate blood volume.
- It helps dispose of old RBC and manufacture new ones
- Processes blood coming from the bowel via portal system.
- The liver produces proteins necessary for blood clotting
4
Q
What is a major by-product of the broken red blood cells in the liver?
A
Bile.
5
Q
What is bile?
A
It is an emulsifier of fat that aids in digestion.
6
Q
What type of blood supply does the liver have?
A
It has a dual blood supply.
7
Q
What does the dual blood supply in the liver consist of?
A
- Hepatic artery supploes approx. 30% of blood flow.
- Portal vein supplies aprox. 70% of blood flow (nutrient rich) from the gastrointestinal tract.
8
Q
The hepatic artery and portal vein comprise the___________.
A
The hepatic inflow
9
Q
What does the portal triad consist of?
A
It is comprised of branches of the hepatic artery, portal vein, and bile duct.
10
Q
Where does the main portal vein begin at?
A
It begins at the confluence of the splenic vein and superior mesenteric vein.
11
Q
Where does the portal veins lie?
A
Anterior to the IVC
12
Q
What happens to the portal vein upon entering the porta hepatis?
A
The MPV divides into the left portal vein and right portal vein
13
Q
What are the anatomy of the RPV (Right Portal Vein)?
A
- Typically larger
- Posterior and caudal
- Divides into anterior and posterior branches
14
Q
What is the anatomy of the LPV (Left Portal Vein)?
A
- Anterior and cranial
- Divides into medial and lateral branches.
15
Q
What are the characteristics of the portal veins?
A
- Conatins NO valves
- Bright, echogenic walls due to thick collagenous tissue
- Course intrasegmentally
16
Q
What does hepatopetal mean?
A
Towards the liver.
17
Q
What does hepatofugal mean?
A
Away from the liver
18
Q
What are the 3 main hepatic veins?
A
Right, middle and left hepatic veins.
19
Q
What veins are the primary outflow for the liver?
A
Hepatic veins.
20
Q
What do the hepatic veins drain into?
A
They drain into the IVC, near the right atrium.
21
Q
What are the characterisitics of the hepatic veins?
A
- Contains NO valves
- Thin-walled vessels
- Courses intersegmentally.
22
Q
Which is the largest of the 3 hepatic veins?
A
The right hepatic vein is typically the largest.
23
Q
What vessels join to form a common trunk before entering the IVC?
A
MHV and LHV
24
Q
What type of waveform does the hepatic veins demonstrate?
A
Pulsatile waveform.
25
Where does the common hepatic artery arise off?
The celiac axis
26
What is it known as once the hepatic artery courses over the anterior-superior edge of the pancreas and gives rise to the gastroduodenal?
The proper hepatic artery
27
Where does the hepatic artery terminate?
At the level of the porta hepatis
28
What are some hepatoporta duplex indications?
* Liver cirrhosis
* Portal hypertension
* Ascite of unknown etiology
* Thrombosis of portal, splenic, and superior mesenteric veins.
* Budd-Chiari syndrome
* Pre & Post-intervention
* TIPS evaluation
* Acute abdominal pain
* Elevated D-dimer
29
What are some risk factors?
* Chronic liver disease.
* Viral Hep.
* Hep B or C
* Metabolic disorders
* Heart disease that results in elevated right-sided heart pressures.
* CHF
* Tricuspid regurgitation
30
What are some hepatoportal duplex vessel assesments?
Gray scale and color:
* Extra- and intra-hepatic portal veins, hepatic veins, and IVC
Spectral Doppler waveforms and velocity measurements:
* MPV, RPV, LPV
* RHV, MHV, LHV
* SV
* SMV
* IVC
* Proper hepatic artery
31
What are some addiditon assessments of a hepatoportal duplex?
* Size and echogenicity of liver
* masses, cyst
* Spleen size (splenomegaly)
* Presence of ascites
* MPV diameter during quiet respiration as it crosses the IVC
32
Portal Vein
Diameter: \<13 mm
PSV: 10-30 cm/s
Flow: Towards the liver
Doppler: Repiro-phasic
33
Hepatic vein:
Diameter: RHV \<6
PSV:22-39 cm/s
Flow: Antegrade and retrograde
Doppler: Pulsatile, multiphasic
34
Splenic vein
Diameter: up to 10 cm
PSV: 9-30 cm/3
Flow: Towards the liver (hepatopetal)
Doppler: Monophasic, slightly pulsatile.
35
SMA
Diameter: Up to 10 cm
PSV: 8-40 cm/sec
Flow: towards the liver (hepatopetal)
Doppler: Monophasic, slightly pulsatile.
36
Hepatic artery
Diameter: smaller than PV
Flow: hepatopetal
Doppler: Low resistance
37
IVC
Diameter: 15 mm to 25 mm
PSV: 44-118 cm/s
Flow: Toward the right atrium
Doppler: Pulsatile, multiphasic, respiro-phasic
38
What is the respiration variation associated with the portal vein?
Diameter: increases with inspiration
Velocity: decreases with inspiration, increases with expiration.
39
What is the respiration variation associated with the splenic vein?
Diameter: increases by 20-100% with inspiration,
Velocity: decreases with inspiration, increases with expiration.
40
What is the respiration variation associated with the SMV?
Diameter: increases by 20-100% with inspiration.
Velocity: decreases with inspiration, increases with expiration.
41
What is ascites?
It is effusion and accumulation of serous fluid in the abdominal cavity.
**Legs are usually swollen as well due to increase abdominal pressure.**
42
What is portal hypertension?
It is elevated portal venous pressure due to impedance of blood flow through the liver.
Causes divided in 3 categories:
1. Prehpatic (inflow)
2. Intraphepatic (liver, sinusoids, and hepatocytes)
3. Posthepatic (outflow)
43
What is the most commong etiology of portal hypertension in north america?
Cirrhosis caused by hep. C
44
What is the primary complication of portal hypertension?
Gastrointensional bleeding from ruptured esophageal and gastric varices.
45
What are the abnormal duplex findings in portal hypertension?
* Increased portal diameter (\>13 mm)
* Increased SV and SMV diameteres (\>10 mm)
* \<20% increase in SMV and SV diameteres with inspiration
* Decreased respiratory variation
* Decreased PV flow velocity
* Hepatofugal flow in the portahepatic veins
46
What is TIPS?
It stands for **transjugular intraheptic portosystemic shunt.**
It is a treatment for portal hypertenson.
47
What does TIPS do?
* It decreases pressure or decompresses the portal venous system.
* A stent is deployed to connect one of the portal veins with one of the hepatic veins (often the right)
* Re-routes blood away from the liver, to the hepatic vein, and back to the heart.
48
How should you asses TIPS?
Obtain velocities and flow direction:
* MPV
* PV end of shunt
* Mid shunt
* HV end of shunt
* IVC or outflow hepatic vein
49
What are normal TIPS duplex findings?
* Hepatofugal flow may be present in intrahepatic portal veins
* MPV= hepatopetal flow.
* Flow should be directed towards the hepatic vein
* Color fil wall-to-wall within stent
* Stent velocities=90-190 cm/s
* MPV and hepatic artery velocities increase from pre-TIPS
50
How do you indentify a stenosis in TIPS?
* PSV \<50 cm/s within stent
* PSV \<30 cm/s within MPV
* A focal increase in stent velocities measuring \>200 cm/s
* A velocity change of \>50 cm/s within stent , as compared to previous exams.
* \>50 cm/s difference in stent velocities from one segment to another
* Reccurent ascite, varices, or splenomegaly
* Retrograde flow in hepatic vein serving as outflow
51
What does thrombosis of the portal, splenic or superior mescenteric vein result from?
* Statis due to cirrhosis and portal hypertension
* Pancreatitis, appendicitis, and diverticulitis
* Hypercoaguable state
* Surgery
* Trauma
* Abdominal malignancy
52
What are the portal venous trhombosis duplex findings?
* Increased PV diameter with intraluminal echoes
* \>15 mm suggest acute thrombosis
* \>23 mm with intraluminal echoes suggest tumor thrombosis
* Non-visualization of PV
* Gallbladder varices
* Increased hepatic arterial flow.
53
What is Budd-Chiari Syndrome?
It is hepatic venous outflow obstruction caused by a thrombosis or tumor.
## Footnote
**Can also be caused by IVC stenosis or occlusion cephalad to hepatic veins**
54
What is the clinical presenation of Budd-Chiari?
* RUQ pain
* Jaundice
* Ascites
* Hepatomegaly
* Liver function abnormalities
55
What are the duplex findings in Budd-Chiari?
* IVC dialation with intraluminal echoes
* Absence of flow in IVC or HV
* Hepatomegaly
* HV dilation with intraluminal echoes
* Sluggish or retrograde flow in PV
* Splenomegaly
* Stenosis or occlusion of HV or IVC
* Ascites
* Collaterals
56
What is the cause of CHF?
DIlation within hepatoportal venous system and IVC
57
What are the characterisitcs of CHF?
* PV flow will be marked pulsatile
* HV=highly pulsatile and demonstrates flow reversal during diastole.
* RHV diameter may increase to \>9 mm in patients with CHF
