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
which test is considered the gold standard for identifying a clot?
venogram
whats a pulmonary angiogram?
radiographic test using contrast to check for a PE
what is a ventilation quotient/lung scan?
and what does it indicate?
how is it reported?
nuch-med study that involves inhaling radioactive gas to show a PE.
indicates perfusion and ventilation of the lungs
as high probability, normal or non high
whats an isotope venography?
is it used often?
much-med study that used an injection of I-125 to evaluate peripheral and pulmonary veins
not used often because it needs 24 hrs to tag the thrombus
whats a D-dimer assay?
how are the result reported?
why is it not ordered as a primary test?
lab test that detects the formation of acute thrombus but assessing the # of fibrin strands in the blood…indicates probably or absent DVT
reported as - (<500ug/L) or + (>500ug/L)
not used often because it will show + in patients who have had surgery, trauma, cancer or are pregnant
what is a Wells’ score for thrombus?
how are the result reported and what is the next step for the patient based on the result
uses a patients hx and signs to estimate the probability of a DVT… each positive fining is given a point
reported as low probability (< or equal to 0) intermediate probability (1 or 2) or high (> or equal to 3)
low or moderate score patients get a d-dimer assay, high score gets US
what is a Wells’ score for PE?
how are the result reported and what is the next step for the patient based on the result
works that same way at score for thrombus…
reporting is low probability (<2) intermediate (2-6) or high (>6)
low to intermediate: D-dimmer
High: VQ scan
what is a phlegmasia alba dolens?
what are the symptoms?
what can it progress to?
decreased venous drainage due to thrombus in the deep veins of the extremities with no collaterals involved
- extensive edema, white discolouration of the leg (capillary circulation is blocked)
- arterial spasms
can progress to phlegmasia cerulea dolens
what is a phlegmasia cerulea dolens?
what are the symptoms?
is it considered an emergency?
massive venous blockage due to multi segment thrombosis of deep veins of the extremities and their collaterals
symptoms:
- arterial vasoconstriction
- arterial thrombus
- cyanosis
- massive thigh and calf swelling
- acute onset of hypoxia leading to gangrene (tiss death)
yes, surgical emerg
what is Paget-schroetter syndrome?
what is it caused by?
who is most commonly effect by this?
most common form of axillosubclavian thrombosis in healthy people occurs when theres a thrombus of axillary/subclavian vein at thoracic inlet
due to anatomical variation of muscle and bone at the thoracic inlet…
men
what is another name for Paget-schroetter syndrome
effort thrombosis
what is thrombophlebitis (superficial)?
how is it diagnosed and what is treatment?
inflammation with thrombus formation
In the superficial system, often diagnosed clinically (hard cord)
-treated by reducing periods of inactivity (ambulation) with compression therapy and anti-inflammatory drugs
what % of superficial thrombosis have a concurrent DVT?
20%
list the non venous pathophysiology that can mimic the symptoms of thrombosis
congestive heart failure (CHF) hematoma abscess and cellulitis bakers cyst tumors Enlarged lymph node (adenopathy) lymphedema (ant farm appearance) popliteal aneurysm
what are some symptoms of CHF?
bilateral lower extremity edema from increased hydrostatic pressure, dyspnea, increased pulsatility in large veins
what are hematomas?
what are their symptoms and how do they appear of US?
Will they have colour flow?
accumulation of blood within tissue
pain and swelling
appear as hypoechoic mass with will ill-defined borders within a muscle of tissue… usually due to trauma
No
what is an abscess? what is cellulitis?
what are there symptoms?
what are they caused by?
Cause by bacterial infection
abscess: enclosed collection of pus
cellulitis: diffuse collection of fluid in the subcutaneous tissue
symptoms: swelling, pain, erythema, tenderness
whats a baker cyst?
symptoms?
where are they usually located?
dilation of bursa (sac of synovial fluid) that connects to the knee join
pain, tenderness, swelling as it gets larger
usually medial to the knee joint
how do baker cysts appear on US?
in which patients are they most common?
anechoic, can contain debris and separations
in those w/ degenerative joint disease and rheumatoid arthritis
will baker cysts show colour flow?
no
how will leg tumors usually appear on US?
why is it important to demonstrate flow in a tumour?
usually solid but may have areas of necrosis
more flow= more likely to be malignant
what are US features of a begnign tumour?
ovoid shape
wider than tall
hypoechoic
has a hilum
what are US features of a malignant tumour?
rounded shape
taller than wide
lots of colour flow
what causes lymphedema?
where is it most common?
chronic limb swelling due to failure of lymphatic drainage system
most common in calf an UE
how does lymphedema appear on US?
thickened subcutaneous tissue that degrades the 2D image
when is a popliteal aneurysm considered possible?
when a patient presents with a lump or pain behind the knee
does the presence of respiratory variation rule out proximal or distal thrombus?
proximal ONLY
is a non compressive vein an indication of chronic or acute thrombus?
acute
do perforator valves close when the calf contracts?
yes
what does the competency of venous flow depend on
- ability of calf to contract
- valve competency
- patency of outflow tracts
with chronic venous insufficiency (CVI) when do symptoms start to present themselves?
when hypertension occurs in the distal veins
what are the 2 underlying causes of CVI?
dysfunctional valves:
- primary: congenital
- secondary: previous DVT or post thrombotic syndrome (damage to the vein after a previous DVT)
chronic outflow obstruction:
- results in collaterals and recanalization which decreases venous return and increases venous pressure
- causes limb swelling and pain
with CVI, do symptoms differentiate the cause
no
Is it more concerning to have CVI in the deep or superficial venous system?
deep
what are the symptoms of CVI?
- swelling
- achy
- varicose veins
- discolouration of the gaiter zone
- ulcers
- stasis dermatitis
- telangiectasis (spider veins)- larger and deeper veins
- reticular vein dilation (sm and superficial veins
list the skin changes that are specific to CVI:
- Edema
- Brawny discolouration: brownish colur in gaiter zone due to RBCs leaking into surrounding tissue
- Ulcerations: often occur near medial malleolus
- Redness/rubor
what is venous claudication?
what is it caused by?
intense burning/cramping in the calf w/ exercise
caused by obstruction of deep Venous sys
what causes venous hypertension and how?
caused by reflux…. due to:
- failed valves
- calf muscle pump doesnt work
- failure of perforator veins which allow flow to reverse from deep to superficial system (superficial is weaker)
what are varicose veins what causes them?
what are the 2 types?
distended veins, >4mm in diameter
caused by reflux
primary
secondary
describe primary varicose veins
what are the 2 items that can cause them?
treatment?
Varicose veins that are restricted to the superficial system only
can be caused by:
- hereditary factors
- increased intramural pressure (due to preg. obesity, prolonged standing)
treatment: surgical ligation/removal of superficial veins, produces a favourable outcome
describe secondary varicose veins
treatment?
varicose veins caused by an obstructive condition in the deep venous system (valve incompetence or previous DVT)
treatment: surgical ligation of perforator veins, pressure stockings`
is stripping of seconding varicose veins beneficial?
no
can you have reflux that is confined to only the deep, or superficial system? or perforators?
yes
how does increased deep venous intramural pressure effect perforators?
may cause them to dilate and the valves to become incompetent
how should the patient be positioned when performing a LE CVI assessment?
standing or severe reverse trendelenburg… can be sitting with legs dangling off bed for calf assessment
does the valsalva maneuver asses for distal or prox valve competency?
prox (we would use this when higher up on the leg)
is augmentation used to assess reflux above or below the knee?
below
what does SFJ stand for?
saphenofemoral junction
what are the names of the 2 valves of the GSV?
terminal and subterminal
how do we document the GSV?
-measure the diameter in TRX at prox, mid and distal
-do colour and spectral and multiple levels
+ from SFJ to ankle
- valsalva and augmentation to asses valves
-checking for accessory veins, duplication and varicose veins
what TRX diameter measurements of the GSV will result in reflux
SFJ: >9mm
Mid thigh: >7mm
Mid calf: >5mm
how do we document the SSV?
- measure the diameter in TRX
- start at ankle and move to SPJ (saphenopopliteal junction)
- do colour and spectral at the SPJ
- check for varicose veins
what are the norm diameter measurement for the SSV?
<2mm
what is it called when the SSV inserts high in the thigh
gacomini vein
is augmentation and qualitative of quantitative measure?
qualitative…. but can be both
which direction do perforators move blood?
in which perforator is valvular insufficiency the most common?
superficial to deep
cocketts (lower 1/3 of calf medial)
what should perforators measure in diameter? where do you take the measurement?
whats the best way to assess the perforators?
<3mm
at the neck of the perforators
with colour doppler
how long does it take for a norm superficial valve to close?
abnormal valve?
will close within 0.5 seconds so a sm amount of reflux may be present
> 0.5 seconds
what quality of flow will abnormal perforators show and how larger will the lumen measure?
bi-directional flow… diameter will be >4mm
is it rare to develop post thrombotic syndrome like ulcers and skin changes in the UE?
yes
list the abnormal valve closer times for each of the venous systems
Deep: > or = 1 sec
Superficial: > or = 0.5 seconds
Perforators: > or = 0.35 sec
purpose of doing CW doppler assessment of LE?
which vessel do we interrogate?
- effective in determining presence and origin of reflux
- used to evaluate acute and chronic disease (assess in the same way at PW)
-looking at GSV, SSV, calf perforators
can CW differentiate between DVT or extrinsic compression?
how do we evaluate the CW signal?
… hard to differentiate because no image
by comparing the sound of the signal when the patients resting to the signal after valsalva or augment
what are the 2 medical treatments for CVI?
injection sclerotherapy:
-for sm varicose veins, injection causes veins to fibrose and obliterate… stops reflux
controlling risk factors:
- limit periods of inactivity, pressure stockings, elevate legs, etc
what are the 3 surgical treatments for CVI?
- ligation (removal) of superficial veins
- vein stripping
- venous ablation
what are the 5 endovascular treatments for CVI?
-radiofrequency ablation
-trans illuminated power phlebectomy:
+ vein is sucked out
-laser thermal ablation
-endovenous ablation
+ a catheter and laser fiber are inserted into the vein at it is cauterized
-phlebectomy:
+multiple incisions are created and the vein is tied off
whats pre-operative venous mapping
what are the advantages?
when US is used to determine availability of super. veins for use as a bypass graft.. commonly used for CABG and LE graft
-allows us to determine size, length, abnormalities before the proceedure
a vessel much have a diameter of > what value to be used for a bypass graft?
> 2.5mm in TRX diameter
why are native veins used more often than synthetic ones?
which vessel is always the first choice?
they have more durability and long term patency
GSV due to length and features (then SSV, FV, basilic and cephalic are evaluated if not good)
What kind of disease does steady and continuous flow indicate?
Proximal disease or proximal extrinsic compression
What is adenopathy?
Swelling of lymphnodes
what % of PEs originate in the lower extremities
80% originate in the LE….
