The IVC is normally situated?
To the right of the Aorta
Anterior to the spine
Where does the IVC terminate?
Into the Right Atrium
The confluence of what two vessels form the IVC?
The common iliac veins
THe IVC is responsible for venous drainage from what vessels?
Lower extremities
Kidneys
Suprarenal veins
Liver via Hepatic veins
Gonadal veins (ovarian and testicular veins)
What does the left gonadal vein drain into? The right?
Left into the Left renal vein
Right into the IVC
The IVC is a low/high pressure system?
Low
How is the size and phasicity of the IVC changed?
With respiration
How does inspiration affect the size of the IVC?
Decreases the size due to a decrease in intrathoracic pressure
How does expiration affect the size of the IVC?
Increases the diameter due to an increase in intrathoracic pressure
How does valsalva affect the IVC?
Halts all venous return in both upper and lower extremities- suspended state
Flow loses phasicity and flows more continuous
What is considered normal flow direction for the IVC?
Towards the Right Atrium
True/False: IVC demonstrates only cardiac pulsations?
False. It demonstrates both cardiac and resiratory pulsations
Where is the IVC most pulsatile?
Proximally; due to the contractions of the Right Atrium
The flow pattern of the distal IVC is more ?
Phasic; similar to other extremity veins
What is the normal size of the IVC?
Varies, but around 3 cm
How is the IVC diameter and body volume related?
Increased body volume=increased IVC size
Depleted body volume=decreased IVC size
How is respiratory variation of the IVC diameter and changes in volume status related?
Increase in total volume=decrease in respiratory variation
Decrease in total volume=increase in respiratory variation
What are the three layers of veins?
Tunica Adventitia (thickest)
Tunica Media
Tunica Intima (contains valves)
What allows veins to be collapsable?
DIminished Tunica Media layer
What is the main reason to US the IVC?
To show patency
If the IVC is not patent, what should be determined?
The cause and location of obstruction
The diameter of the IVC can increase what percentage with respiratory maneuvers?
10%
What occurs in conjunction with many cardiac conditions, due to the failure of the IVC to drain properly?
Dilation of the IVC
What are some of the common causes of IVC dilation>
Right ventricular heart failure
Congestive heart disease
Constrictive pericarditis
Tricuspid disease
Right heart obstructive tumors
What is the most common pathology to affect the IVC?
Thrombus
How does thrombus usually propagate into the IVC?
From a tributary vessel
What is a secondary cause of IVC thrombus?
An obstruction that causes reduced flow, such as neoplasm growth
What syndrome is commonly associated with IVC thrombus?
Budd-Chiari Syndrome
Where is the thrombus usually located with Budd-Chiari syndrome?
In the hepatic veins extending into the IVC
True/False: IVC filter placement can cause thrombosis?
True
Why are IVC filters placed?
To prevent an embolus from breaking off and traveling into pulmonary circulation
How/where are IVC filters placed?
Placed via catheter through the CFV or IJV in interventional radiology
Must be placed below the renal veins
How does IVC filter placement work?
The filter expands and attached to the wall of the IVC and traps the thrombus
How does acute IVC thrombus appear?
Distended IVC
Absence of flow
Fresh is generally more anechoic
Presence of material within the vein lumen
If a clot is coming from a tributary, the clot can sometimes ?
Float freely, allowing flow to move around the thrombus
If continuous flow is seen, it should prompt investigations for obstruction in more?
Proximal portions of the IVC
How does a fresh thrombus appear? Chronic thrombus?
Fresh- anechoic
Chronic-ecogenic
What are some different causes of IVC compression?
Pregnancy, persistent ascites, large abdominal tumors
What can compression of the IVC cause?
Edema in feet and ankles
Varicose veins
Supine hypotension
What is the second most common pathology of the IVC?
Neoplasm
What extrinsic tumors can cause compression or invade the IVC?
Renal Cell Carcinoma
Hepatocellular Carcinoma
Cancers that invade abdominal lymph nodes
Primary tumors of the IVC are rare
How should a thrombus be differentiated from a tumor?
Color imaging
Tumors will be vascular
Thrombus will be avascular (internally)
Where does the rare double IVC occur?
The infrarenal portion of the IVC
What is the most common type of double IVC?
When the Left IVC joins the LEft Renal Vein, which then drains into the Right IVC
What causes infrahepatic interruption?
Thought to be congenital; rare
What is infrahepatic interruption?
Membranous obstruction of the IVC
How is membranous obsruction of the IVC caused?
Interrupted by an oblique or transverse fibrous septum which is usually located just cephaled to the insertion of the right hepatic vein
What are symptoms of infrahepatic interruption?
BLE swelling and signs of hepatic obstruction
What is infrahepatic interruption often in conjunction with?
Major acyanotic and cyanotic cardiac disease and incomplete situs inversus
How is blood flow returned to the heart with a congenitally absent IVC?
Collateral conduits
-Azygous and hemizygous veins (lumbar veins)
The collaterals discharge blood into the?
SVC and then returned to the Right Atrium
What is the largest tributary of the IVC?
Hepatic veins
At what level do the Hepatic veins enter the IVC?
The diaphragm
Blood from the hepatic veins are returned back into?
Systemic circulation
How should Doppler waveform appear?
Multiphasic, pulsatile from the right atrial pulsations
Augmented waveforms of Hepatic veins are?
Pulsatile, Triphasic, and change with respiratory maneuvers
Does inspiration/expiration have better waveforms with the Hepatic veins?
Expiration; due to decreased IVC pressure
What is a common cause of dilated Hepatic veins?
Congestive Heart Failure
What can CHF also cause?
Increased pulsatility of LE and other peripheral veins
How does CHF change the waveform of the Hepatic veins?
Inverted "W"
Markedly pulsatile flow
The Right HV is often greater than ? with CHF?
9mm
What is Budd-Chiari Syndrome?
Acute obstruction of hepatic venous flow
What symptoms do patients develop with Budd-Chiari Syndrome?
Hepatomegaly from vascular conestion
Abdominal pain
New onset of ascites with liver disfunction
Where can obstruction take place with Budd-Chiari?
Hepatic veins
IVC
Centrally within the sinusoids of the liver (veno-occlusive disease)
What are the US findings with hepatic vein occlusion?
Visualized thrombus or tumor with absent or disturbed flow related to partial obstruction
What are the US findings with IVC occlusion?
Clot or tumor; often due to propagation from hepatic veins
How does the liver tissue appear with Budd-Chiari?
Congested and hypoechoic
What happens to the caudate lobe of the liver with Budd-Chiari?
May enlarge due to it having its own blood supply
What happens to the waveform of the hepatic veins when affected by Budd-Chiari?
Becomes monophasic because they lose there pulsatility
What is the drainage from the respective reproductive organs?
Gonadal veins
Where does the Left gonadal Drain? The right?
Left- Left Renal Vein
Right- IVC
What drains the Adrenal Glands?
Suprarenal veins
Where does the Left Suprarenal Drain? The Right?
Left- Renal Vein
Right- IVC
How many branches form the main renal vein?
5 or 6
Where does the left renal vein arise?
Medial to exit the hilum
What is the flow from the left renal vein?
Left Kidney> posterior to SMA/anterior to AO> enters IVC
What does the Left renal vein accent as a tributary?
Gonadal Vein
What is the flow of the Right Renal vein?
Flows directly from the Right Kidney into the posterolateral aspect of the IVC
Does the Right Renal Vein accept tributaries?
Rarely
What happens to the volume of the IVC after the Renal veins enter?
The volume is increased
Which renal vein is larger? Why?
Left. Because it accepts tributaries from the gonadal, adrenal and lumbar veins
Who is renal vein obstruction often seen in?
Dehydrated or septic infants
Renal vein obstruction can be seen in adults due to?
Renal Tumor
Nephrotic syndrome
Kidney transplant
Trauma
Severe Hydronephrosis
Patients with renal vein obstruction present with?
FLank pain
Hematuria
Proteinuria
US findings of patients with renal vein obstruction show?
Enlarged kidneys
Anechoic areas in the renal parenchyma due to hemorrhage
Renal vein thrombosis show direct visualization of?
Thrombus within the renal vein and possibly the IVC
What are the US findings with Renal vein thrombosis?
Renal vein dilation proximal to the point of occlusion
Loss of normal structure/parenchyma
Increased renal size ACUTELY
Decreased or absent flow on Doppler
The confluence of what veins form the IVC?
Common Iliac Veins