DVT and PE's Flashcards

1
Q

Which 3 factors of the anticoagulant pathway regulate clot formation by preventing excess thrombin production?

A

Protein C and S and antithrombin

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2
Q

What are the components of Virchow’s triad?

A
  • Venous stasis
  • Endothelial damage
  • Hypercoagulability
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3
Q

What is the most common thrombophilic disorder; leads to what?

A
  • Factor V Leiden mutation –> activated protein C resistance
  • Results in protein C being unable to inactivate factor V and VIII, which leads to unregulated prothrombin activation
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4
Q

What is a pro and con of using D-dimer in the assessment of DVT/PE?

A
  • Pro = negative test makes DVT unlikely; simple to perform
  • Con = positive test is not diagnostic of DVT; other conditions can elevate D-dimer
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5
Q

What is considered the gold standard screening modality for DVT/PE in intermediate cases; what are some pros and cons of using it?

A
  • CT pulmonary angiography (CT angiography)
  • Pros: high sensitivity and specificity; accurate anatomy assessment
  • Cons: requires contrast (allergies, AKI), expensive, radiation exposure, and may miss small peripheral clots
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6
Q

What are the pros and cons of using ventilation/perfusion scans in the evaluation of DVT/PE?

A
  • Pros: high sensitivity + inexpensive
  • Cons: low specificity + may not demonstrate small sub-segmental defects
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7
Q

What is the tx for factor V leiden mutation in pt with no prior episodes vs. prior episodes of thrombosis?

A
  • No prior episodes: just observation; DVT prophylaxis and risk reduction
  • Prior episodes: consider lifelong anticoagulation
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8
Q

A mutation in the prothrombin gene at position G20210A causes what?

A

↑ levels of prothrombin that leads to excess thrombin formation

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9
Q

In a patient whose clot does not respond to heparin therapy, which inherited thrombotic disorder should be suspected; why?

A

Antithrombin III deficiency; since heparin requires the presence of antithrombin because it enhances the activity of antithrombin

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10
Q

Why is the incidence of DVT of the upper extremities rising in incidence?

A

Secondary to ↑ use of indwelling venous catheters

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11
Q

The syndrome of DVT includes thrombosis in which 2 areas?

A
  • Proximal leg veins
  • Large veins of the upper extremities
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12
Q

If the D-dimer is positive or if the clinical likelihood of DVT is high which imaging modality should be used?

A

Duplex ultrasonography = excellent sensitivity and specificity

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13
Q

What is the most effective treatment for prevention of VTE in hospitalized pt’s with risk factors?

A

Pharmacologic prophylaxis

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14
Q

Which agent is used most often for longer-term anticoagulation in pt with established DVT; describe how it’s administered and the guidelines that need to be followed?

A
  • Warfarin
  • Typically initiated w/ heparin and both used for minimum 5 days until INR = 2-3 for 2 measurements taken 24 hrs apart
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15
Q

What are some pros and cons of the newer anticoagulant agents, dabigatran, rivaroxaban, apixaban, and edoxaban?

A
  • Oral, rapid onset, do not require monitoring or overlap w/ heparin; minimal interactions with foods and other meds
  • Most cannot be used in pt’s w/ significant kidney failure
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16
Q

Once a patient with established DVT is on stable anticoagulation they should be treated for a minimum of how long?

A

3 months

17
Q

If there are strong indications to anticoagulant therapy in pt with established DVT what treatment option exists; what are some downfalls to this treatment?

A
  • An inferior vena cava filter should be placed
  • Will ↓ likelihood of PE in short-term, but they may actually ↑ the long-term risk of recurrent DVT
18
Q

In clinically stable pt’s with a low probability of PE, which lab value can effectively rule out PE and is correlated with an excellent outcome without further workup or tx?

A

Normal D-dimer

19
Q

What is the indication for using D-dimer in pt’s with a higher probability of PE or clinical instability?

A

D-dimer testing should not be used to confirm or exclude the diagnosis and further testing is indicated

20
Q

What are the pros and cons of using doppler venography for DVT/PE evaluation?

A
  • Pro: inexpensive, easy, no radiation, and flow physiology
  • Cons: tech. dependent + ↑ false positives/negatives
21
Q

A totally normal finding using which imaging modality is the only one that can exclude PE?

A

V/Q scan

22
Q

What would be the imaging modality of choice to use in a patient with renal failure or someone who is obese for initial assessment of PE?

A

V/Q scan

23
Q

When may thrombolytic therapy be effective in patient with PE?

A
  • Pt’s with circulatory shock to PE
  • Pt’s with acute embolism and pulmonary HTN or RV dysfunction by without arterial hypotension or shock
24
Q

A patient with a Wells Criteria score of 0 or lower for DVT should be managed how?

A
  • Should proceed to d-dimer testing
  • A (-) high or moderate sensitivity d-dimer –> no further test
  • A (+) d-dimer should precede to U/S testing
  • If U/S (-) is sufficient to rule out DVT
  • If U/S (+) concern for DVT; strongly consider anticoagulant tx
25
Q

A patient with a Wells Criteria score of 1-2 is considered to be at what risk of DVT and how should they be managed?

A
  • Moderate risk (pretest probability = 17%)
  • Should proceed to high-sensitivity d-dimer test
  • A (-) test is sufficient to rule out DVT; a (+) test warrants U/S
  • (-) U/S is sufficient for ruling out DVT
  • (+) U/S is concerning for DVT, strongly consider anticoagulation therapy
26
Q

Which Wells Criteria score for DVT suggests that a DVT is likely and has a pre-test probability 17-53%?

A

3 or higher

27
Q

Which 2 findings using the Wells Criteria for PE are associated with a score of 3?

A
  • Clinical sx’s and signs of DVT
  • Alternative diagnosis LESS likely than PE
28
Q

Which 3 findings using the Wells Criteria for PE are associated with a score of 1.5?

A
  • HR >100 bpm
  • Immobilization for >3 days or surgery in previous 4 weeks
  • Previous PE or DVT
29
Q

Which 2 findings using the Wells Criteria for PE are associated with a score of 1?

A
  • Hemoptysis
  • Cancer (with tx within past 6 months or palliative care)
30
Q

Using the Wells Criteria for PE, which score is associated with a high, moderate, and low risk of PE?

A
  • High = >6
  • Moderate = 2-6
  • Low = <2
31
Q

Heart failure appears to be a hypercoagulable state and the risk of DVT may be greatest in which type?

A

Right heart failure

32
Q

List 7 acquired prothrombic states which increase risk for thromboembolism.

A
  • Antiphospholipid antibodies
  • Malignancy
  • Immobilization
  • Surgery
  • Pregnancy
  • Estrogen
  • Heparin-induced thrombocytopenia