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Pulmonology > Venous Thrombosis > Flashcards

Venous Thrombosis Flashcards

1
Q

What are four severe consequences of VTE?

A

Sudden death

Cardiovascular collapse, cardiac arrest

Chronic thromboembolic pulmonary hypertension (due to recurring small PE’s)

Postphlebitic syndrome (DVT) = valves get damaged, so you can’t get fluid out of the legs –> edema, ulceration

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2
Q

Where can you get DVT?

A

Lower extremity: proximal are most important clincially

Upper extremity: 10%, catheter associated, Paget-Schroetter syndrome (large muscles in neck)

Pelvic and renal veins

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3
Q

What’s Virchow’s triad for VTE:

A

Stasis (hospitalization, travel, cast, pregnancy

Endothelial injury (trauma, catheter, surgery)

Hypercoagulable (malignancy, HF, oral contraceptives)

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4
Q

What are the 2 most inherited risk factors for VTE?

A

Factor V Leiden mutation

Prothrombin gene mutation

(Also: protein S deficiency, protein C deficiency, antithrombin deficiency)

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5
Q

What’s the acute presentation of DVT?

A

Pain, swelling, erythema in extremity

Asymmetry, warmth, edema, cords (thrombosed external veins)

Differential diagnosis: muscle strain, cellulitis, ruptured baker’s cyst, postphlebitic syndrome

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6
Q

Wells Score for DVT

A
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7
Q

What test is a good way to rule out DVT?

A

D-dimer, because it’s very sensitive: elevated in nearly all pt with DVT

If it’s negative, it’s probably not DVT

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8
Q

Which tests can you use to detect DVT?

A

Duplex ultrasonography: noninvasive test of choice

Contrast venography: gold standard

Also: magnetic resonance venography, CT with contrast

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9
Q

How can you treat DVT?

A

Anticoagulatns:

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10
Q

Unfractionated heparin

A

Complexes with antithrombin & inactivates thrombin, factor Xa, IXa, XIa

Narrow therapeutic window

Fully reversible with protamine

Does not cross placenta

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11
Q

LMWH

A

Complexes with antithrombin & inactivates thrombin, factor Xa, IXa, XIa

Subcutaneous injection

Reduces recurrent VTE & bleeding compared to UFH

Follow Xa in pregnant, obese, elderly, renal dz

Better bioavailability than Heparin so better prediction of how it will affect pt

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12
Q

Fondaparinux

A

Newer synthetic agent

Subcutaneous injection

Inactivates factor Xa directly

Equally effective as LMWH for VTE, similar precautions

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13
Q

When do you transition to oral anticoagulants?

A

i.e. warfarin

Should overlap with heparin 4-5 days, when all factors are sufficiently reduced

Treat for at least 3 months

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14
Q

What are your options for oral anticoagulatns?

A
  • *Warfarin**: should overlap with heparin for 4-5 days, when all factors are sufficiently reduced, treat for 3 months at least, watch out for DDI, also it’s teratogenic
  • inhibits vitamin K-dependent gamma-carboxylation of factors II, VII, IX, X

Dabigatran: direct thrombin inhibitor, the one in tv commercials, 2x/day, no monitoring

Rivaroxaban: also direct Xa inhibitor, takes effect immediately

All are equally effective

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15
Q

What are your other options for DVT therapy?

A

Catheter directed thrombolysis

IVC filter

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16
Q

What is a pulmonary embolism? What can cause it?

A

Obstruction of pulm artery or branches with material originating from elsewhere in the body (emboli from DVT, air, tumor, fat, foreign material)

17
Q

What’s the pathophysiology of PE?

A

Thrombi lodge in main PA or smaller branches

Platelets release vasoactive & bronchoactive agents i.e. serotonin

Rarely pulm infarcation

18
Q

How do you get hemodynamic compromise in acute PE?

A

Pulm Emboli –> increased pulm vasc resistance –> RV strain & reduced LV preloado –> reduced CO, RV ischemia, RV failure –> cardiovascular collapse/cardiac arrest due to R heart failure

19
Q

What gas exchange abnormalities do patients with acute PE get?

A

Hypoxemia, hypocapnea, respiratory alkalosis (due to high RR) though not necessarily present always

V/Q mismatch: pulm blood flow redirected towards regions of low alveolar ventilation

Intrapulmonary shunting: observed & happens though unclear why

20
Q

Clinical presentation of acute PE: Signs and Symptoms

A

Symptoms: dyspnea, pleuritic pain, leg pain/swelling, cough, wheezing, hemoptysis

Signs: tachypnea, DVT signs, tachycardia, abnormal breath sounds, signs of right heart failure

All are in order of most common to least common

21
Q

Wells score to predict PE

A

Clinical symptoms of DVT = 3

Other diagnosis less likely than PE = 3

HR >100 = 1.5

Immobilization/surg within last 4 weeks = 1.5

Previous DVT/PE = 1.5

Hemoptysis = 1

Malignancy = 1

If >4 PE likely 37% chance

If <4, PE unlikely 12% chance

22
Q

What diagnostic tests can you do for PE?

A

CT pulm angiography (CTA): most widely available, good diagnostic accuracy, requires IV contrast (nephrotoxic) & radiation exposure

V/Q scan: inject labeled albumin, inhale radioactive gas – assess V/Q mismatches

Duplex ultrasonography

Echocardiography: for risk stratification

Pulm angiography

MR angiography

Lab markers: D-dimer, cardiac troponins, BNP
- helpful in risk stratifying more than diagnosing

23
Q

How do you treat acute PE

A

Stabilize the patient: supplement O2, hemodynamic support if needed

Assess probability of PE and bleeding risk

Obtain diagnostic tests

Treatments: anticoagulation (for almost all), thrombolysis (selected pt’s), IVC filter (if unable to receive anticoag or recurrent PE), emolectomy by catheter or surgery

24
Q

How do anticoagulants work?

A

They prevent thrombus propagation & allows endogenous fibrinolytic activity to resolve clots

Variable rates of PE thrombus resolution - several days to months

Anticoagulants prevent recurrent PE & reduce mortality

Risk of bleeding is less than 3%

25
Q

How do you decide which anticoagulants to use in acute PE?

A

LMWH or fondaparinux preferred: less bleeding

Unfractionated heparin in unstable pt & those with high risk of bleeding (because you can reverse it with protamine if they start bleeding)

Transition to warfarin for 3 months or more

26
Q

When do you use thrombolytics?

A

Massive PE

Bc it has a higher risk of bleeding than anticoagulation

27
Q

How can you do VTE prophylaxis?

A

Heparin 5000 units SC twice daily

LMWH heparin 400 mg SC daily

Warning if recent GI bleeding or thrombocytopenia

Aspirin and warfarin are not used for prophylaxis

28
Q

What is the prognosis of PE?

A

30% mortality if untreated

2-8% mortality with anticoagulation (shock on presentaiton = most important determinant)

Recurrent PE occurs in 3% of patients & is associated with 79% mortality

29
Q

What is the VTE risk in medical patients?

A

Low risk = young & ambulatory: 0.3%

High risk on thromboprophylaxis is 2%

High risk if off thromboprophylaxis is 11%

No formal system of risk is in practice

Consider prophylaxis if >age 40, limited mobility for >3 days, or have another risk factor

Pulmonology (16 decks)

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