C5&6: Acute and Chronic Venous Pathophysiology Flashcards
what is the order for optimizing 2D images?
depth
focus
TGCs
gains
in general, when can an acute DVT occur?
if theres a change in the normal hemodynamics or architecture of the venous sys
What is Virchows triad?
which factor in the trade is the most common factor for acute DVT?
3 causes of DVTs:
stasis
hypercoagulability
intimal injury
stasis
what are some of the most common cause of UE DVTs
vein wall injury due to a central line or venous catheter or trauma
list some examples of causes of hypercoagulability
- pregnancy
- Birth control
- genetic factor
- deficiency of protein C & S which are anticoagulants produced in the liver
- cancer
what is hypercoagulability
blood clots too fast
what are some indication for a LE US
edema, swelling (especially unilteral) limb pain ulcerations cyanosis or discolouration varicose veins \+ D dimer test
how are 50% of acute DVTs diagnoses?
clinically
what are 2 potential complications of acute DVTs?
whats the mortality rate for PE?
- PE
- low O2 blood pooling in legs
30% mortality rate if not treated
what are some indication for a UE US
history of catheter line or drug abuse
head and neck swelling, redness, pain
potential injury after venous puncture or catheterization
what are the symptoms of PE?
which one is the major indicator of PE?
shortness of breath, chest pain, coughing up blood (hemoptysis)
hemoptysis
common symptoms of an acute DVT
acute onset of pain, swelling, redness, warm skin, unilateral swelling (usually)
what patient Hx increases the likelihood of an acute DVT
previous DVT clotting probs trauma surgery bed rest for > 4 days
describe the formation of a clot
early formation starts as aggregation of RBC near the valve cusps due to stasis and eddy currents…
…then they’re stabilized by fibrin… once stabilized, the thrombi stick to the endothelium and propagation occurs
where do enlarging pockets form and how?
form b/w the clot and vein wall through a combination of fibrinolysis, thrombus retraction and fragmentation
whats the most common outcome of the acute DVT?
Resolves by itself with some intimal wall thickening
residual fibrous synechia occurs in what % of patients?
10%
what consists of an acute thrombus? and what US indication will confirm a acute DVT?
1-2 weeks old and consistent with the timing of clinical symptoms
dilation of leg vein and lack of compressibility
what are the most common sites for acute DVTs?
calf veins (in the soleal sinus and gastruc veins? valve cusps venous confluences deep venous system superficial venous sys perforators
describe the US findings for acute DVT
enlarged vein, vein will not coapt
how will the clot appear in an acute DVT
- isoechoic or slightly echogenic…
- the proximal end of an acute thrombus may not stick to the wall and may float in the lumen (the clot can easily be dislodged)
- spongy texture
what is collateralization? is it an acute or chronic sign?
accessory vessels that re-route flow around an obstruction
can be both
how might a DVT effect valves? and how can we determine this?
may make them incompetent… diagnosed by showing reversal of flow with valsalva or compression proximal to the site of the valve
what characteristics of venous flow indicate proximal disease?
continous venous flow without phasicity
if we dont get an augmented signal when augmenting, what does this indicate?
distal thrombosis (distal to the probe, not distal to augmentation site)
what is recanalization?
blood begings to flow through channels in the clot
what characteristics make a sub-acute thrombus?
- 1-2 months old
- clot may show increased echogenicity and decrease vein diameter because clot is breaking down
- may be some recanalization and formation of collaterals
what characteristics make a chronic thrombus?
- chronic thrombotic scarring due to thrombosis occurring months to years ago
- reminding fibrous tissue will appear moderate to highly echogenic and may be isoechoic to surrounding tissue
US findings of chronic DVT
- echogenic thrombus
- vein smaller than artery
- collaterals
- recanalization
- irregular texure
can veins be partially or completely incompressible in both acute and chronic stages of DVT?
yes
when do DVTs start to breakdown?
~2 weeks
can we always determine the age of the thrombus?
no
where is the most common site of thrombus in the calf veins?
soleal sinuses
how are acute calf DVTs often treated?
surveillance with US and anticoagulation therapy for 6 wks
what type of doppler signal in the CFV will you get if theres an acute DVT in the iliac veins?
flow wont be spontaneous in the CFV…
what is May-Thurner Syndrome?
what can is lead to?
compression of the left CIV between the right CIA and spine (5th lumbar vertebra)
increased risk for DVT, L CIV stenosis and L leg swelling
if you compare the bilateral CFV and both are monophonic, where is the clot likely located?
IVC
is a clot in the superficial venous system benign or problematic?
benign
what % of patients with DVTs will go on to have chronic venous insufficiency?
60%
what locations of a DVT are considered life threatening?
anywhere from popliteal to iliacs
why is a calf DVT not considered fatal?
the thrombus is too small to be fatal, even if it causes a PE (this is why they dont treat it)
what are the medical treatments for acute DVT and what do they do
anticoagulants (standard treatment): prevent clot propagation, dont dissolve
thrombolytic agent: streptokinase is injected into the thrombus to dissolve it…. especially for UE clots
controlling the risk factors: limit long periods of inactivity, elevating legs, etc
what are the surgical treatments for acute DVT and what do they do
IVC filter: strains blood so clot cant cause a PE… for patients who cant use anticoagulant
venous thrombectomy:: removal of the clot of streptokinase doesnt work…. this patient has impending limb loss
bypass grafting: allow the flow to bypass the clot
what are the endovascular treatments for acute DVT and what do they do
- catheter directed thrombosis
- mechanical thrombectomy
- balloon venoplasty and stending (for chronic iliofemoral DVT)
what is a venography/venogram
when would you do an ascending vs descending venogram?
Xray that uses contract material injected into the leg to show any disease that might be present
ascending: for acute disease
descending: for valve disorders
how will a complete thrombus be seen on a venogram?
as a lack of filling of the contrast within the vein
can you differentiate between acute and chronic DVT with venogram?
no