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Flashcards in Venous Thromboembolic Disease Deck (24):

What effects will a DVT have on the limb itself? (3 main things)

Chronic venous damage (which increases risk of recurrent DVT).


Pulmonary embolism is bad. What happens?

Pain, dyspnea, infarcted lung, hypotension, death.


Pulmonary embolism is a complication of venous thromboembolic disease (VTE). So if you see a patient with PE, what should you think about?

You should figure out why the patient got a DVT.


Review: What's Virchow's Triad?

3 factors that promote blood clot:
Vascular injury.
Venous stasis.


Typical spots for DVTs to form?

At valves - where there is some eddy/stasis.
Sites of trauma/surgery - where there is vascular injury.


Important hereditary causes of hypercoaguability?

Protein C and S deficiencies...
Factor V Leiden (..but MDTI emphasized this really isn't that significant)
Prothrombin mutations.


Important acquired cause of hypercoaguability?

(and HIT. MDTI says forget about antiphospholipid Abs)


Why does hip surgery put a patient at big risk for DVT?

Not only is there vascular injury, but the patient won't be moving that leg for a long time -> stasis.


95% of PE come from lower extremity DVTs.

That makes sense, given there are more things that make you stop moving your legs than there are that make you stop moving your arms.


PE causes dead space in alveoli whose capillary beds are blocked by the clot, but what other effects does it have?

Mediators cause bronchospasm of nearby airways -even if those capillaries are normal -> low V/Q.
Mediators cause vasoconstriction at distant sites -> high V/Q.

So PE causes dead space, and all sorts of V/Q mismatch.


Recall that the right heart really can't deal with afterload. What does this mean for PE?

PE quickly causes right heart failure.


Major risk factors for VTE? (think about Virchow's triad!)

Vascular injury: major surgery, trauma, prior VTE.
Hypercoaguability: malignancy.
Stasis: Immobilization, recent hospitalization.


How is obesity a risk factor for VTE?

It's hard to isolate obesity itself, but there may be impaired venous drainage.


Does everyone with PE have a big swollen limb?

Of course not. < 30% of patients with PE have symptoms of DVT. 25% have no symptoms.


What are the most sensitive symptoms of PE?

Dyspnea and pleuritic pain (present about 70% of time)... but of course, these are not specific at all.


Lots of things can mimic PE, but what's one alternate you really want to rule out before starting anticoagulation?

Aortic dissection.


What tests do you do if you suspect PE?

Look at the legs with ultrasound (not sensitive).
Look at the lungs... typically with HRCT (but can see things on CXR, vent/perfusion scan).


Blood test you can do to look for clotting?

D-dimers. High sensitivity, low specificity.
So it's nice for ruling out VTE if your suspicion is low.


Treatment for VTE / PE?

Thrombolytics (for "massive" PE)
Anticoagulation - heparin.
Prevent recurrences with warfarin, others.


Review: MoA of heparin?

Binds antithrombin III and makes it more effectively inhibit prothombotic factors like thrombin, Xa, IXa.


Review: MoA of warfarin?

Inhibits vitamin K synthesis - reducing activity of those Vit K-dependent clotting factors.


Desired duration of anticoagulation post-VTE event is debatable.



Mechanical therapy to prevent PE in people who can't be anticoagulated (or who are very high risk)?

Filter in the IVC.


People who are hospitalized have tons of VTE risk factors. What should you do about that?

You should actively prevent clots from forming.
Think about low-dose anticoagulation with heparin.
Take patients for walks.

(For every single patient, ask if he/she should be getting DVT prophylaxis!)