Week 6 Flashcards
Where do lower extremity DVT’s most commonly originate?
calf veins at the valve leaflets
may extend proximally into calf and thigh
What are the signs and symptoms of lower extremity DVT?
lower extremity swelling and pain (unilateral)
swelling more likely cardiovascular in origin and secondary to heart failure
What’s the pathophysiology of Virchow’s triad?
Venous stasis- more time for clotting, small clots not washed away, inc blood viscosity
Vessel wall damage- accidental/surgical trauma
Blood coagulability increase- inc in tissue factor, presence of activated factors, dec in coag inhibitors
What are 3 hyper-viscosity syndromes?
heparin induced thrombocytopenia (platelet deficiency)
myelodysplasia (cancer of immature bone marrow blood cells)
polycythemia (too many RBC in bone marrow)
The Homan’s sign is a reliable diagnostic tool for DVT. True or false
False
can be positive w/ other conditions such as gastrocnemius tears
Palpable cords are an unreliable sign of DVT. True or false
True
often found in patients with SVT instead of DVT
Accuracy of clinical diagnosis of DVT is
50%
Wells score:
estimation of probability of DVT prior to ordering an ultrasound
based on clinical risk factors
What are the positive criteria of the Wells score
\+1 point for each active malignancy (within 6wks) paralysis, paresis or recent plaster immobilization of lower limb bedridden >3days major surgery/trauma within past 4 wks localized tenderness along lower extremity veins swelling of entire lower limb pitting edema swelling greater than 3cm
In the wells score, calf swelling greater than ____ as compared to asymptomatic leg yields a point.
3cm
Peripheral edema:
seen in both legs
can be due to aging of the veins, or other conditions that put pressure on the leg veins
Wells score negative criteria:
-2 points for DDx as likely as DVT
Wells score final totals:
probability of DVT:
high >3 points
intermediate 1-2 points
low <0
What are the most common means of measuring pretest probability for DVT?
d-dimer
Wells score
If there is a low pretest probability and a negative d-dimer test, what treatment is necessary?
none
In patients with a high pretest probability for PE or DVT, the D-dimer assay should not be obtained since the negative predictive value of the assay is low. True or false
true
Patients can be treated on the basis of a + d-dimer test test alone. True or false
false
What increases the pulsatility of the Doppler waveform in the EIV and CFV?
tricuspid valve regurgitation or rt. sided heart failure
Thrombus in the _____ _____ or ____ will flatten the Doppler signal and eliminate respiratory variation and cardiac pulsations in the CFV and below.
EIV and IVC
What can also eliminate/reduce the respiratory variation in veins below the inguinal ligament?
compression by pelvic or inguinal masses
ascites
What is the gold standard for US evaluation of DVT?
compression
What is primary diagnostic criterion for DVT?
lack of venous compression or complete coaptation of walls intraluminal echoes color void-complete or partial lack of spontaneous flow absence of respiratory variation high sensitivity for thigh DVT low sensitivity for calf thrombus
What is the best way to treat DVT? (not really a great question but it was a bullet point lol)
prevention!
The part of Virchow’s triad with the greatest impact is venous stasis. What do we use to keep blood flowing?
calf venomotor pump
can also elevate the lower extremity to aid gravity
What do compression stockings do?
keep the vein at a smaller diameter, pushing blood upward and not allowing it to pool into stasis dermatitis
precursor to venous ulcers
What is the medical treatment for DVT?
anticoagulants - initially heparin injection, then oral drug started within 24-48h
Inadequate anticoagulation in the first _________ may increase risk of recurrence or PE.
24 to 48hrs
Acute DVT can be treated on an outpatient basis unless:
severe symptoms require parental analgesic other disorders preclude safe outpatient discharge other factors (functional, socioeconomic) that prevent the patient from adhering to prescribe treatments
What’s the goal for DVT treatment? (primary and secondary)
primary- PE prevention
secondary- symptom relief, prevention of DVT recurrence, chronic venous insufficiency and postphlebitic syndrome
Are treatment of upper and lower DVT the same?
yes, generally
Which anticoagulant is taken orally? Which one is injected?
oral- warfarin, factor Xa or direct thrombin inhibitor
injected- heparin
Warfarin is also known as?
coumadin
What anticoagulants are most often used?
low molecular weight heparins (LMWHs) unfractionated heparin (UFH) fondaparinuv warfarin non-warfarin oral anticoagulants (factor Xa inhibitors, apixaban. Direct thrombin inhibitors- dabigatran)
An IVC filter may help prevent PE in patients with:
LEDVT who have contraindications to anticoagulant therapy recurrent DVT (despite adequate anticoagulation)
Where is an IVCF placed?
in IVC just below renal veins, via catheterization of IJV or FV
What are some complications of the IVCF?
migration
tilts/shifts
fractures
perforation
Thrombectomy:
includes percutaneous mechanical thrombectomy and pharamalogical thrombolysis
most invasive and used prior to new methods
With percutaneous mechanical thrombectomy, the thrombus can be mechanically removed via
a catheter inserted into the CFV
it macerates the thrombus and suctions it away. Uses medicines that prevent clot formation
Streptokinase, urokinase and alteplase lyse clots, and may be more effective to prevent postphlebitic syndrome than heparin alone, but
the risk of bleeding is higher than with heparin
Thrombolytic therapy alone may be indicated for
large proximal thrombi
those in iliofemoral veins, and for phlegmasia alba or cerulea dolens
Historically, if DVT’s persisted a patient would have to do surgical bypass reconstruction. What do they do now instead? Why?
Balloon dilations and stents
less invasive
Where do they feed the venous balloon dilation catheter
vein near the groin
Duration of treatment is typically
3-6mo
depending on presence and nature of risk factors
some people may need lifelong treatment
What are some early preventative measures for DVT?
early mobilization, leg elevation, compression stockings/devices/both and anticoagulants
(required for bedbound patients w/ major illness or those undergoing certain surgical procedures)
