Module 6 : Liver Vasculature Flashcards
hepatic artery
- primary blood supplier (30%)
- tortuous
- low resistance
proximal HA
- best seen in transverse
- at celiac axis
+ is celiac axis occluded then HA can still get flow from collaterals
distal HA
- viewed intercostally
- ## at level of main portal vein
spectral tracing of normal HA
- low resistance
- fill in of spectral window due to small artery diameter
- variable viscosities due to tortuosity
- RI 0.5-0.7
resistive index RI
- EDV/PSV
- EDV decreases = more resistive
- stronger indicator of stenosis then velocity
inferior vena cava IVC
- formed by union of the common iliac veins
- anterior to the spine and to the right of the aorta
- intercostal scans are best to visualize
IVC spectral waveform
- spontaneous waveform (no provocative maneuver)
- Proximal = more pulsatile closer to heart
- distally = phasic (further from heart)
- respiratory changes
IVC size
- changes with size of patient
- respiration
- right atrial pressure CHF
- > 3.7 dilated
hepatic veins
- three major veins
- accessory veins are common (more on right)
- drain into IVC
- hepatic veins enlarge as they approach the IVC
- intersegmental
- commonly left and middle come together first
- with agenisis RHV usually absent followed by middle then left
right hepatic vein RHV
- runs coronally between anterior and posterior segments of the right lobe
- largest
middle hepatic vein MHV
- lies between right and left lobes
- medial left lobe
left hepatic vein LHV
- runs between the medial and lateral segment of the left lobe
- commonly duplicated
caudate lobe
- has its own drainage directly into IVC
spectral trace hepatic veins
- multiphasic
- pulsatile flow
- flow away from transducer
- if not showing this flow there may be an obstruction
walls of hepatic veins
- less defined then PV
- no echogenic sheath
patency and distension hepatic veins
- indications of Budd Chiari or CHF
- BC = narrowed or absent
- CHF = not phasic or pulsatile
hv scanning window for confluence
- trans subxiphoid
- lots of color close to heart
hv scanning window RHV
- right intercostal
hv scanning window MHV
- midline subxiphoid
- intercostal
hv scanning window LHV
- anterior subcostal
- angle heel toward left
portal veins
- drains nutrient rich blood from bowel and spleen to the liver (70%)
- formed by confluence of the splenic vein and SMV
+ IMV and coronary veins contribute - enters liver at porta hepatic
portal veins spectral trace
- low velocity \+ range = 15-40 cm/sec \+ mean = 15-18 cm/sec - continuous signal - subtle phasic variations (undulations) - windstorm sound
portal veins flow
- hepatopedal (toward flow)
- increases post prandially
+ vessels dilate near bowel when you eat which increases flow
scanning window MPV
- anterior subcostal
- intercostal
- always over ivc
scanning window RPV
- intercostal
- coronal
scanning window LPV
- subxipoid
- intercostal
liver duplex exam - assessing
- flow direction
- normal waveform
- patency
liver duplex exam - routine vessels
- hepatic veins
- portal vein
- splenic vein
- hepatic artery
- collaterals
dopper assessment liver duplex
- assess flow quality
- only assessed during quiet respiration
patient positon
- supine
anterior window
- assess \+ LPV \+ LHV \+ SV \+ MPV
coronal intercostal
- assess \+ RHV \+ MHV \+ RPV and MPV \+ HA
color and spectral doppler of liver
- done in every picture
- flow direction
- quality of flow NOT QUANTITY
- patency
hepatic veins assess
- hepatofugal (away from liver) flow
- multiphase waveform
portal veins assess
- hepatopedal
- subtle phasicity
MPV - protocal
- 2D (anterior subcostal)
\+ measure AP
\+ anterior to IVC
\+ with quiet respiration
\+ normal measurement less than 13mm
- color and spectral trace (coronal intercostal)
\+ sample MPV outside of liver
\+ coronal intercostal
= zero angle
\+ anterior subcostal
= 60 angle
\+ measure peak velocity with generic callipernormal range of peak velocity of MPV
- 15-40 cm/sec
splenic vein - protocol
- color and spectral (anterior subcostal)
- long axis
left hepatic - protocol
- color and spectral (anterior subcostal)
- long axis
left portal vein - protocol
- color and spectral
- subxiphoid window
- long axis
- not doing velocity
right hepatic vein - protocol
- color and spectral
- right intercostal window
- long axis
- closest to diaphragm
middle hepatic vein - protocol
- color and spectral
- midline subxiphoid
- intercostal
- long axis
right portal vein - protocol
- color ade spectral
- coronal intercostal
+ same as MPV - not doing velocity
hepatic artery - protocol
- color and spectral (coronal intercostal)
- same window and area as MPV
- measure PSV
- patient may hold breath for this image only
splenic vein - protocol
- closer to heart
- more crazy waveform
IVC - protocol
- subxiphoid
- long axis
- close to diaphragm
flow tips - portal vs vein
- portal venous flow is slower than hepatic vein so adjust flow
sweep speed
- medium
portal vein baseline
- move down a little
hepatic vein baseline
- move up slightly
intercostal scanning tips
- rotate transducer to go between ribs
- point transducer indicator toward patient right scapula
portal hypertension
- elevated pressure in portal venous system
+ impedes blood flow through the liver
portal hypertension - causes
- volume overload
- increased resistance to flow
three classifications of portal hypertension
- pre-hepatic
- intrahepatic
+ most common - post hepatic
pre-hepatic portal hypertension - casues
- portal of splenic thrombosis
- portal or splenic invasion
- extrinsic compression by a tumor
intrahepatic portal hypertension - causes
- hepatocelluar disease
+ CIRRHOSIS
+ hepatitis
+ fatty infiltration
post hepatic portal hypertension - causes
- thrombosis of hepatic veins (Budd chiari)
- thrombosis of IVC
- congestive heart failure
- right sided heart disease
risk factors of portal hypertension
- chronic liver diseases that precedes fibrosis or cirrhosis
- heart disease resulting in increased right sided heart pressures
chronic liver disease that precedes fibrosis or cirrhosis
- viral hep (chronic hep B or C)
- alcoholic liver disease
- autoimmune disorder
+ primary biliary cirrhosis, primary sclerosing, cholangitis - metabolic and genetic disorders
+ hemochromatosis, Wilsons disease - schistosomiasis
- non alcoholic steatohepatitis NASH
- sarcoidosis
heart disease leading to increased right sided heart pressure s
- tricuspid regurge
- congestive heart failure
- constrictive pericarditis
patient clinical signs - portal hypertension
- ascites (abdominal distention)
- splenomegaly
- GI bleed
- JAUNDICE (COMMON SIGN OF CIRRHOSIS)
- abnormal LFTs
can patients be asymptomatic with portal hypertension
- yes
manifestations of signs and symptoms associated with underlying disease - portal hypertension
- pancreatitis
- liver diseases
patient history - portal hypertension
- could have variceal hemorrhage (hematemesis and melena)
- bacterial peritonitis
physical exam of patient would see - portal hypertension
- jaundice (if liver sufficiently impaired)
- splenomegaly (could lead to low platelet counts)
- dilated abdominal wall veins
- hepatic encephalopathy (confusion due to poor liver function)
ultrasound evaluation would document - portal hypertension
- portal vein diameter > 13mm
- cavernous transformation (intraabdominal collaterals)
- portocaval anastomoses
- dilation/ recannalization of umbilical vein
- splenomegaly > 13cm
duplex eval - patency of vessels (collaterals too)
- color doppler
+ flow or lack of flow - power doppler
+ tortuous vessels and collaterals
duplex eval - direction of flow
- color and spectral
- possibility of reversed flow in portal/splenic veins
duplex eval - loss of phasic variation
- special tracing
- in response to respiration
- Changs to biphasic with progression to flow reversal
+ increased pressures
duplex eval - presence or absence of thrombosis
- 2D
- color
+ decease or absent of flow
+ not indicative of hypertension in patients with chronic liver disease
duplex eval - PV velocity
mean velocity 15-18 cm/s
pulsatile and dilated IVC mean what
congestive heart failure
portal vein thrombosis - primary condition
- can be found in patients with
\+ liver disease
\+ hypercoagulable states
\+ intestinal inflammation
= appendicitis, diverticulitis,
- causes increased resistance in portal venous circulationultrasound findings - portal vein thrombosis
- enlarged PV
- lack of flow or decreased flow
- collateral flow
- enlarged hepatic artery and increased flow
- tumor
- portal vein occlusion
PVT - enlarged PV
- look for thrombus in lumen
+ variable echogenicity
PVT - lack of flow or decreased flow
- spectral color or power doppler
PVT - collateral flow
- chronic PV thrombosis
- cavernous transformation/shunts
PVT -tumor
- invasion of portal vein
- typically hepatocellular and pancreatic carcinoma
- presence of arterial flow within thrombosis
- partial blockage
+ at site of obstruction = increase speed and disturbed flow patterns
+ distal to obstruction = continuous flow no respiratory changes
PVT - portal vein occlusions
- usually permanent
- fibrotic changes cause vessel to virtually disappear
three pitfalls of scanning for PVT
1) undetected anechoic thrombus/tumor
2) low velocity flow undetected
3) inadequate doppler angle precluding detection of flow
hepatic vein occlusion (budd chiari syndrome) - causes
- post hepatic portal hypertension
- thrombosis
+ increases hypercoagulability
= oral contraceptives, polycythemia, hemoglobinuria - compression
- tumor invasion
- cirrhosis
- membraneous obstruction of IVC
hepatic vein occlusion - signs and symptoms
- hepatomegaly
- abdominal pain
- acute development of ascites
- abnormal liver function tests
- splenomegaly and collaterals may be evident in chronic cases
hepatic vein occlusion - ultrasound findings
- hepatomegaly
- caudate lobe hypertrophy
- thrombus or tumor in HV or IVC
- ABSENCE OF FLOW
- if veins are narrow
+ focal elevation of velocity
+ turbulence - deep liver
+ segmental lack of flow and bicolor - collaterals
+ connecting patent HV with the portal system
+ bypasses the occluded segment - IVC should be evaluated to rule out thrombus or tumor causing secondary obstruction to hepatic veins
normal portal vein - ultrasound
- low velocity (15-30cm/s)
= hepatopedal flow - respiratory variations
hepatic artery - ultrasouns
- low resistance flow
- PSV 70-150 cm/s
hepatic vein - ultrasound
- multiphase flow
right sided heart failure/tricuspid regurge - ultrasound
- increase HV pulsatility
- pulsatile PV and IVC
portosystemic collaterals and shunts
- obstruction of major vessels forces blood to take a secondary route
- flow directed toward mesenteric, splenic and portal veins
collaterals
- preexisting vessels
- blood flow completes circulation back to IVC
- secondary vessels dilate
- high risk rupturing
most common collateral routes
- at esophagus
+ near the stomach
+ under the left lobe of the liver
+ near the spleen
coronary vein (left gastric vein)
- > 7mm
- most common collateral
+ reversed flow in 80-90% of PH cases - can progress to esophageal varices
- presence clinically important
+ implies increased risk for variceal hemorrhage
coronary vein - location
- anterior to CA bifurcation
- posterior to common hepatic artery or splenic artery
- follows oblique path travelling superior to the left of portosplenic confluence
umbilical vein
- remnant of the umbilical vein
+ located in the lig teres - from the umbilicus to the tip left portal vein
- hepatofugal flow
- normally measure less than 3mm no blood flow
most common collaterals
- coronary vein
- umbilical vein
- splenorenal vein
surgical shunts
- decompress the portal system
- surgical or endovascular
- in severe cases of portal hypertension or cirrhosis
surgical shunts effective for
- reducing ascites
- preventing hemorrhage from gastroesophageal varices
- improving quality of life of patio nest with severe cirrhosis
trans jugular intrahepatic portosystemic shunt TIPS
- most common
- metallic expandable stent
+ installed percutaneously
+ IJV into HV through liver tissue to PV
+ duplex US to assess - success 90%
- subject to high rate of stenosis or occlusion
- compensatory increased flow seen in HA
TIPS - early complication
- stenosis or thrombosis
- first few weeks of stent placement usually due to thrombosis
TIPS - late complication
- neointimal hyperplasia invading stent
TIPS - most common site of stenosis
- hepatic vein end
post surgery
- baseline study
- regular follow up
TIPS - normal ultrasound
- patent TIPS
- TIPS velocity range 90-190cm.s
- PV peak velocity 30cm/s
- similar velocities at each end
- pulsatile wave form
- MPV caliber up to 15mm
- PV and Sv - hepatofugal flow
- RPV/LPV flow towards stent
TIPS - abnormal ultrasound
- no flow
- focal area narrowing
- velocity gradient > 100cm/s at stenosis
- TIPS velocity < 50cm/s
- PV velocity <30cm/s
- continuous flow
- RPV?LPV flow away from stent
transplant liver
- treatment for end stage liver disease
- duplex US used inure and post op assessment of patient s
pre op liver transplant scan
- assessment for patency of \+ portal vien \+ hepatic artery \+ hepatic vein \+ IVC - detect tumors in liver or surrounding tissue - biliary tree status
post op liver transplant scan - performed
- within 24 hours post op
- follow up at 1 6 and 12 month
post op liver transplant scan - color and spectral
- confirms patency of all major vessels
\+ hepatic artery (most important)
= RI : 0.5-0.8
= PSV : < 200 cm/s
= acceleration time : < 0.08 sec
- assess anastomosis sites
- flow direction and vessel size
\+ portal vein normal up to 15mmpost op liver transplant scan - 2D
- liver parenchyma
- biliary tree
- perihepatic spaces
post transplant complications
- HA thrombosis
- stenosis
- viability of liver is critical to hepatic artery inflow
- hematoma
- abscess formation
- AV fistulas
HA thrombosis - liver transplant
- MOST COMMN
- within first 6 weeks
+ absence of flow
+ dampening of PSV
+ decreasing diastolic flow - stenosis of anastomosis sites
- PV thrombosis, air (PV larger up to 15mm)
stenosis - liver transplant
- at surgical anastomosis
post op liver scan - doppler
- appropriate doppler angle critical
+ HA tortuous
+ sample along artery starting at celiac axis
portal hypertension sonographic signs
- ascites
- MPV diameter > 13mm
- splenic vein diameter > 10mm
- patent umbilical vien
- paraumbilical vein > 2.5. mm
- splenic length > 13mm
- portal vein thrombosis
- +/- cavernous transformation of MPV
- slow PV flow
- alternating retrograde/antergrade PV flow
- hepatofugal flow in portal/splenic vessels
- coronary vein retrograde flow
- esophageal varices
budd chiari (hepatic vein occlusion) - sonographic signs
- hepatomegaly
- caudate lobe hypertrophy
- decreased absent or reversed flow in any HV
- narrowed IVC
- thrombus in IVC or HV
- dampened HV spectral trace
- collaterals within liver tissue
congestive heart failure
- increased right heart pressure
- PV pulsatile
- HV increased pressure
+ W PATTERN - dilated IVC
