Venous Thromboembolic Disease

Question 1

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

Answer 1

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

Question 2

Pulmonary embolism is bad. What happens?

Answer 2

Pain, dyspnea, infarcted lung, hypotension, death.

Question 3

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

Answer 3

You should figure out why the patient got a DVT.

Question 4

Review: What’s Virchow’s Triad?

Answer 4

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

Question 5

Typical spots for DVTs to form?

Answer 5

At valves - where there is some eddy/stasis.

Sites of trauma/surgery - where there is vascular injury.

Question 6

Important hereditary causes of hypercoaguability?

Answer 6

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

Question 7

Important acquired cause of hypercoaguability?

Answer 7

Malignancy.

and HIT. MDTI says forget about antiphospholipid Abs

Question 8

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

Answer 8

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

Question 9

95% of PE come from lower extremity DVTs.

Answer 9

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.

Question 10

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

Answer 10

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.

Question 11

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

Answer 11

PE quickly causes right heart failure.

Question 12

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

Answer 12

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

Question 13

How is obesity a risk factor for VTE?

Answer 13

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

Question 14

Does everyone with PE have a big swollen limb?

Answer 14

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

Question 15

What are the most sensitive symptoms of PE?

Answer 15

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

Question 16

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

Answer 16

Aortic dissection.

Question 17

What tests do you do if you suspect PE?

Answer 17

Look at the legs with ultrasound (not sensitive).

Look at the lungs… typically with HRCT (but can see things on CXR, vent/perfusion scan).

Question 18

Blood test you can do to look for clotting?

Answer 18

D-dimers. High sensitivity, low specificity.

So it’s nice for ruling out VTE if your suspicion is low.

Question 19

Treatment for VTE / PE?

Answer 19

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

Question 20

Review: MoA of heparin?

Answer 20

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

Question 21

Review: MoA of warfarin?

Answer 21

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

Question 22

Desired duration of anticoagulation post-VTE event is debatable.

Answer 22

Okay

Question 23

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

Answer 23

Filter in the IVC.

Question 24

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

Answer 24

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!)