Module 7 Liver Vasculature Flashcards
The evaluation of the portal system is a common procedure often related to what?
Chronic liver disease and cirrhosis of the liver
Liver vasculature evaluation includes the evaluation of what? 5
- Hepatic veins
- Portal veins
- Hepatic Artery
- IVC
- Collaterals
Some of the vascular disorders we will look at are what? 3
- Portal hypertension
- Shunts/Stents
- Transplants
What are two types of portal hypertension?
- Portal vein thrombosis
- Hepatic vein thrombosis
How many major hepatic veins are there?
Three
Where do the MHV and the LHV typically join?
Before the IVC
Which Hepatic vein is typically duplicated?
Left hepatic veins
What do the hepatic veins drain into?
The IVC and become larger in diameter on their approach
What does Hepatic Vein waveforms look like typically?
Respirophasic and pulsatile
Why do we evaluate the hepatic veins?
We assess for patency or distension
What does this image demonstrate?
The hepatic veins draining into the IVC
What does the portal veins drain?
Blood from the bowel and spleen to the liver
How much blood does the portal veins supply to the liver?
Approximately 75%
The MPV is comprised of what?
Splenic and superior mesenteric veins
The MPV enters the liver through what?
The porta hepatis
When describing flow in the portals and hepatic veins we use what terms?
- Hepatopetal
- Hepatofugal
What does hepatopetal mean?
Towards the liver
What does hepatofugal mean?
Away from the liver
Portal veins have a low velocity normally, what is the range?
16-40 cm/s (variable- depends on source)
What is the flow relatively for portal veins post prandial?
Flow increase post prandial
The normal MPV diameter should be what?
Less than 13 mm
What does this image demonstrate?
MPV
What does this image demonstrate?
LPV
What does this image demonstrate?
RPV
How much blood does the hepatic artery supply to the liver?
25%
What kind of path does the Hepatic artery have?
tortous
Where is the proximal hepatic artery seen?
At the celiac axis
Where is the distal hepatic artery seen? 2
- Intercoastal
- MPV and RPV
Where is the distal hepatic artery seen?
- Intercoastal
- MPV and RPV
What is the resistance like in the hepatic artery?
Low resistance
Is there normally spectral broadening in the hepatic artery?
Yes, because the vessel is quite small
What is the velocities of the Hepatic artery?
Variable so RI is used to assess for pathology
What is the normal Resistive index?
0.5 - 0.7
What is the IVC formed from?
Iliac veins
Where is the IVC located?
Anterior to the spine and right of the aorta
What is the size of the IVC?
Variable, greater then 2.5 cm considered dilated
What does the IVC spectral trace look like? 3
- Spontaneous waveform?
- pulsatile proximal
- Phasic distally
What is the IVC spectral trace influenced by?
Heart and respiration
What categories can portal hypertension be categorized into? 3
- Pre- hepatic
- Intrahepatic (most common)
- Post hepatic
What is the leading cause of portal hypertension?
Cirrhosis
What is the leading cause of cirrhosis?
Hepatitis C followed by alcoholism
What are the signs and symptoms of portal hypertension? 5
- Jaundice
- Abnormal LFT
- Ascites (increased abdominal girth)
- Splenomegaly
- GI bleed
What are two types of GI bleeds?
- Hematemesis (vomiting blood)
- Melena (dark starry stools)
For a portal hypertension physical examination the patient can present with what? 2
- Caput medusae (dilated abdominal wall veins)
- Hepatic encephalopathy (confusion due to poor liver function)
What is Pre-hepatic obstructions?
- Pathology that occurs to blood flow before it enters the liver (inflow)
What are some examples of pre-hepatic obstruction? 4
- Portal or splenic vein thrombosis
- Portal or splenic vein invasion
- Extrinsic compression by tumor
- Inflammation of the pancreas (pancreatitis)
Portal vein thrombosis can be caused by what? 5
- Cirrhosis (20%)
- Malignancies (20%)
- Hypercoagulable states
- Intra- abdominal inflammation/ infection
- Trauma (From surgery)
Chronic PHT may be asymptomatic or symptomatic?
Asymptomatic
What does Portal vein thrombosis look like sonographically?
Can appear enlarged (>15mm)
How may the lumen echogenicity appear during portal vein thrombosis? 4
- Hyperechoic
- Hypoechoic
- Isoechoic
- Anechoic
What might the portal vein thrombosis appear in spectral?
There may be an absence of flow with spectral, color, or power doppler
What might portal vein thrombosis look like? 2
- Cavernous transformation
- HA enlarged/ increased flow
Portal vein thrombosis tends to last how long?
It tends to be permanent leading to scarring
What happens to the vessels during Portal vein thrombosis?
The vessel virtually disappears
What are three pitfalls to be aware of for portal vein thrombosis?
- Undetected anechoic tumor/ thrombus
- Low velocity flow undetected
- Inadequate doppler angle
What is the most common cause of portal hypertension?
Intrahepatic obstruction
What are intrahepatic obstruction underlying diseases? 4
- Cirrhosis
- Hepatitis
- Hepatic fibrosis
- Nonalcoholic steatohepatitis (NASH)
What is intrahepatic obstruction? And what does it lead to?
Inflammation of normal liver tissue which leads to death and fibrosis
What does Intrahepatic obstructions lead to? 4
- Damage to liver, sinusoids and hepatocytes
- Increased resistance to blood flow at the sinusoid level
- Shunting of blood to collateral vessels
- Varicies develop
Near the end stage of intrahepatic obstruction what happens to the liver and spleen?
The liver will decrease in size and the spleen will increase in size
What is this an example of?
Liver cirrhosis
What is poste hepatic obstruction?
When drainage of blood from liver (outflow) is compromised
What is post-hepatic obstruction caused by? 3
- Chronic right sided heart failure
- Tricuspid regurgitation
- Budd chiari (thrombosis of the HV and IVC)
If Post hepatic obstruction is acute, what does the liver do?
The liver enlarges and so does the spleen
For post hepatic obstruction if there is increased right side heart pressure what can be the cause?
CHF or TR
What is the the spectral of PV look like?
Pulsatile
What is Budd chiari?
A rate condition that is most commonly caused by a hyper coagulable state like polycythemia
What drugs can also lead to thrombosis somtimes?
Oral contraception
What collaterals sometimes form during budd chiari?
They may form a caudate lobe which may help drain the liver
What does this image demonstrate?
IVC obstruction
What does the image demonstrate?
Hepatic vein obstruction
What is the patency of MPV and branches? What are some questions we should ask? 3
- Presence or absences of thrombus
- Is there lack of flow?
- Are there collaterals?
What are some questions we should ask when doing duplex documentation? 4
- What is the patency of MPV and branches
- What is the direction of flow
- What is the phasicity
- What is the MPV velocity
What is MPV velocity?
16-40 cm/sec
What are waveform changes? 2
When the waveform becomes either
1. Bi-phasic
2. Flow reversal
What does waveform changes mean? 2 (biphasic/ flow reversal)
- If its bi-phasic - alternative antegrade/ retrograde flow
- If its flow reversal- severe PHT
Why do collaterals flow?
In the event of portal hypertension is a key finding
How many way can we take to return to the heart?
There are several natural collateral pathways
What are alternative ways to bypass the liver and decompress the system?
Surgical intervention such as therapeutics shunts are used in severe cases to prevent GI bleeds and improve quality of life
What are portosystemic collateral and shunts? What do they normally drain into?
- Pre- existing vessels
- Normally drain into portal, splenic, and mesenteric vessels
What are the three major congenital shunts?
- Portocaval
- Mesocaval
- Splenorenal
What does the portocaval drain?
PV to IVC
What does the mesocaval drain?
SMV to IVC
What does the splenorenal drain?
SV to Lt. RV
Why would we use portosystemic collaterals and shunts?
SO vessels develop or recanalize with portal hypertension to allow blood to circulate back to the IVC
What does the portosystemic collaterals and shunts look after a while?
Seen as dilated vessels and appear as “too many tubes” or a “can of worms”
A backup of blood flow ends up where in the portosystemic collaterals and shunts?
A backup of blood flow ends up in the organs they are draining and cause enlargement (splenomegaly)
what is the most prevalent portosystemic collateral?
The coronary vein (left gastric)
Increased pressure in the coronary vein may cause what?
Esophageal varices
Why does increased pressure causes the coronary vein to cause esophageal varices?
These vessels are not made for the volume of blood they now receive
Visualization implies an increase risk for what?
Hemorrhage which is life-threatening
With PHT the remnant of the umbilical vein does what? What is the flow? 3
- Recanalizes in the ligamentum teres
- From the LPV to the umbilicus
- Flow is hepatofugal
What kind of devices can decompress the portal system? How can it be inserted?
A surgical shunt, it can be placed surgically or with an endovascular technique
The most common shunt for PHT is what?
TIPS
What does TIPS stand for?
Trans-jugular intrahepatic portosystemic shunt
What is TIPS?
A metallic, expandable stent is placed in the liver tissue shunting blood from PV to HV
What is the endovascular technique for placing TIPS?
Catheter passed down IJV into HV, Advancing through liver tissue into PV branch
What is the success rate for TIPS?
100%
What should we do to follow up for TIPS?
Assess with TIPS
What does this image demonstrate?
TIPS
Ultrasound is used to confirm what in terms of TIPS?
Patency and search for stenosis
In a normal TIPS the velocity range is what?
90-190 cm/s
Normal PV velocity is at least what?
30 cm/s
What is the flow in TIPS? 2
- Flow is retrograde in the right and left portal
- Compensatory increased flow seen in HA
What is early complication of TIPS? What can this increase/ decrease?
- Usually due to thrombosis
- Will increase velocities in the stenosis (>190cms)
- Can decrease velocities in the MPV (<30 cms)
What is late complications of TIPS?
Neo- intimal hyperplasia invades stent
What is neo-intimal hyperplasia?
An over reaction of the bodies normal healing process
If a stenosis is detected in TIPS what do we do?
Balloon angioplasty and thrombolysis can be done
What is a liver transplant used for?
Treatment for end stage liver disease
How much of a liver can be used for a liver transplant?
Whole or partial (typically right)
what is used for pre and post operative assessment liver transplant patients?
Duplex ultrasound
During post operative assessment what doe we look at to confirm patency, flow direction and size? 4
- HA
- PV
- IVC and HV
- Splenic and mesenteric veins
What may be larger in the liver transplant patient? And what is the normal size?
The portal vein can be larger in the transplant patient with normal size up to 15 mm
What are complications to transplant livers? 6
- Rejection
- Pseudo aneurysm
- Hepatic infarction
- Thrombosis of major liver vessels
- Stenosis may be observed at the surgical anastomosis sites in follow up exams
- Other concerns can be hematomas, abscess formation and AV fistulas
What are some thrombosis’s that might be complications in liver transplants? 3
- HA thrombosis early post-op complications
- Stenosis of anastomosis sites
- PV thrombosis, air
When is a ultrasound usually done after a liver transplant?
Typically done within 24 hours of the surgery and at regular intervals afterwards
The HA should have what type of appearance in the post liver transplant?
Should have a rapid upstroke and an RI
What should the RI be for a post transplant liver?
0.55 - 0.8
What can we note about PSVs in the transplant liver?
PSV is variable and is not reliable
HV’s can have what type of waveform post transplant?
Monophasic waveform immediately after the surgery but will normalize over time
