CM- Pulmonary Vascular Diseases Flashcards
Where do most pulmonary emboli originate? How do they get to the pulmonary arteries?
Most originate in deep veins of the leg: 1. femoral 2. popliteal But they can also come from: 3. iliac 4. IVC 5. upper extremity veins
They dislodge from the wall of the vein, travel through the great veins and lodge in pulmonary arteries
How do most DVT develop?
Virchow’s Triad
- Venous stasis- recent paralysis, cast, +/- bedrest
- Injury to vein wall - catheter, physical trauma, minor injury
- Hypercoagulable state - inherited/acquired
More than half of individuals with a first-diagnosis of venous thromboembolism have one of what 4 risk factors withoin the prior 90 days?
- hospitalization
- malignancy
- surgery
- major trauma
In addition to hospital admission, trauma, malignancy, and surgery, what are the other important risk factors for DVT/PE?
- OCP
- pregnancy
- immobility of lower limbs
- acute infectious disease
- older age
- family history of hypercoagulable state
What are the 3 most common physical exam findings of DVT?
- unilateral leg swelling
- palpable venous cord in thigh/calf
- Homan’s sign- pain with foot dorsiflexion
A meta-analysis on DVT found that the only significantly helpful INDIVIDUAL physical exam finding for predicting PE occurrence was:
Difference in calf diameters by 3 cm
How is the Wells Rules scored?
What is the only thing that gives “negative” points?
High probability = >3
Moderate score = 1-2
Low score <0
Alternative diagnosis as likely or greater than DVT gives -2 points
What is the most common diagnostic test used to confirm a DVT?
What are the 2 parts of the test?
Where is this test highly sensitive and specific for DVT?
What veins can it NOT be used for?
Non-invasive compression Duplex ultrasonography:
- compression - shows areas of the vein that are non compressible due to clot
- Doppler- confirms lack of blood flow
It is highly sensitive and specific for DVT below the inguinal ligament (legs) but cannot image clots in the iliac vein or IVC
When compression duplex ultrasonography is inconclusive or cannot be performed (pelvic vein or IVC) what test would be ordered?
Venography - invasive test that is the Gold Standard for DVT but not frequently used due to invasive nature and use of contrast (a cause of allergic reactions or renal failure)
What is the gold standard test overall for DVT?
Why is it not commonly used?
Venography- it is not commonly used because it is invasive and requires contrast which can cause allergic reaction and renal failure in patients with renal disease.
When is a CT scan a good choice for looking for pelvic vein DVTs?
When you are already doing a CT angiogram on the chest for PE.
It is invasive and requires contrast, but imaging the pelvic veins requires no EXTRA contrast from what was being used in the chest to look for PE
Congenital deficiencies in what 3 factors and mutations in what 2 factors are thought to increase the risk for DVT?
How would you know to look for inherited hypercogulable states?
The following are natural anticoagulants that decrease clot formation by inhibiting/degrading clotting factors. Deficiencies cause thrombus formation
- Protein C
- Protein S
- Antithrombin III
Gene mutations can lead to abnormal:
- prothrombin
- factor V (Leiden)
The conditions are autosomal dominant so when taking the family history, note if a parent or sibling has DVT or PE history.
What is the most common of the inherited anticoagulable states?
Factor V Leiden - resists protein C mediation which increases the risk for thrombus formation
Patients with inherited hypercoagulable states have DVT at a _______ age, without _____________, and thrombus form in ____________________.
Younger age, without clinical risk factors, and thrombus form in unusual locations like arms or mesenteric veins
What are acquired deficiencies that lead to hypercoagulable states?
anti-phospholipid antibodies:
- lupus anticoagulant
- Anti-cardiolipin antibodies
Is hyperhomocystinemia acquired or inherited?
What can lead to increased levels?
It can be acquired, inherited or both as a common genetic variant.
Deficiencies in folate, B12, or B6 can lead to hyperhomocystenemia which increases risk for DVT
What preventable risk increases the relative risk of a heterozygous with Factor V Leiden from 7 to 35?
OCP
Who has a higher risk for developing a DVT, a person with homozygous Factor V Leiden or someone in their first year off anticoagulation after an idiopathic DVT?
Off anticoagulant = 7-8% incidence per year
Factor V Leiden = 0.5-1% incidence per year
Who has the highest risk for developing a DVT?
Cancer
Recent surgery
Trauma
Hospital admissions
What are the pros and cons of genetic testing for patients with venous thrombus at young age?
Pros:
Factor V Leiden patients can avoid going on birth control or estrogen pills
Con:
-Most patients will not have different treatment based on testing
-asymptomatic carriers do not require anticoagulation
The effect of a pulmonary embolism on a patient depends on what two factors?
What % of pulmonary circulation needs to be occluded to result in sudden death or profound cardiogenic shock?
- size of the clot
- amount of pre-existant cardiopulmonary disease
75% occlusion can lead to sudden death/cardiogenic shock
Most PE do not cause infarction of the lung because the lung has _______________.
However, in the 1/3 of cases where there is infarction, what are the clinical signs?
Lung has dual blood supply so it usually will not infarct.
If it does, the patient will present with:
1. hemoptysis
2. fever
3. pleural friction rub
and a wedge shaped infarct, often mistaken for pneumonia
What are the most common symptoms of a common PE?
- tachypnea- because perfusion is blocked but ventilation is fine. Breath faster/deeper due to increased dead space
- acute dyspnea- (most other dyspnea is gradual)
- Chest pain
What are the 3 most common symptoms associated with a large PE?
- Tachycardia
- syncope
- hypotension
What are the three symptoms suggestive of a PE causing an infarct?
- Pleural Rub
- fever
- hemoptysis
What are the 3 basic diagnostic tests done for PE?
- ABG- hypoxemic with large A-a gradient and acute respiratory alkalosis due to tachypnea. PaO2 <1.5mg/L in a low suspicion person = no extra tests
- CXR
- D-Dimer