Venous Thromboembolisms Flashcards
________ of persons who survive the first occurrence of Venous Thromboembolism (VTE) develop another VTE within _________.
1/3
10 years
What is Virchow’s Triad?
An explanation of VTE pathogenesis. Three risk factors overlap to lead to a thrombosis:
- Stasis (—> alterations in blood flow)
- Vascular endothelial injury
- Hypercoagulability (alterations in the constituents of the blood - inherited or acquired)
Previous thrombotic event is associated with a major risk for _________
A recurrent VTE
Majority of patients with VTE fulfill most or all of Virchow’s triad
In over 80% of patients with VTE, a risk factor can be identified
Chronic conditions —> risk of VTE
Chronic conditions (CHF, IBD, etc) ***Malignancy Obesity ***Antiphospholipid antibody syndrome Advanced age Smoking ***Myeloproliferative disorders
Transient States —> risk for VTE
**Recent surgery (esp ortho)
**Trauma
***Immobilization
Presence of a central venous catheter
Hospitalization
Infections
Extended travel
Female specific risk factors for VTE
**Pregnancy
Post-partum
**Hormonal contraceptives
Hormone replacement therapy
In other words, ESTROGEN
Inherited risk factors for VTE
Inherited Thrombophilia
**Factor V Leiden mutation
**Prothrombin gene mutation
(50-60% of cases are these two)
Protein S deficiency
Protein C deficiency
Antithrombin deficiency
Classic symptoms of DVT include:
Swelling, pain, and erythema of the involved extremity
Not necessarily a correlation between the location of the symptoms and the site of the thrombosis (pain can be more distal)
Other symptoms:
Warmth
Increased calf diameter***
Palpable cord
Homan’s Sign
A positive sign is present when there is pain in the calf with forceful and abrupt dorsiflexion of the patient’s foot at the ankle while the knee is extended
Fallen out of favor for Dx of DVT b/c low sensitivity/specificity
________________ is the most studied and therefore most commonly used pretest probability scoring system for DVT
Wells (and modified Wells) score
Used before diagnostic tests to confirm or help rule out DVT
Score of 3 or greater = high probability
Active cancer = +1 Immobilization = +1 Recent surgery = +1 Localized tenderness = +1 Swelling = +1 Calf swelling > 3 cm = +1 Pitting edema = +1 Collateral superficial veins = +1 *Alternative diagnosis more likely = -2
Problems with the Wells criteria
3 points are related to swelling alone (can overlap)
“Alternative diagnosis more like” is subject
Serum D- Dimer
1st dx test outside of Hx
Degradation product of cross-linked fibrin (high when there’s a clot)
Detectable at levels > 500 ng/mL in virtually all patients with VTE
**Sensitive but NOT SPECIFIC - useful only when negative
Therefore only order when there’s a low or moderate pretest probability of DVT (skip if high probability)
Previous gold standard for Dx DVT
Contrast Venography
No longer recommended as first line b/c pt discomfort and difficulty
Test of choice for Dx of DVT
COMPRESSION ULTRASOUND!
Loss of vein compressibility, using Doppler technique to asses blood flow
Noninvasive, relatively available, inexpensive, and easy to perform/read
May need serial exams to definitely rule out
When to treat a DVT
Absolutely treat for proximal DVTs (popliteal, femoral, iliac)
Appropriate to treat many distal DVTs as well especially if symptomatic
Purpose of DVT treatment
Prevent further clot propagation
Prevent PD
Reduce risk of recurrent VTE
Reduce complications (ie post-thrombophlebitic syndrome, chronic venous insufficiency)
Mainstay Tx for DVT
Anticoagulation
Initial anticoagulation immediately for up to 10 days
Long term but finite anticoagulation for a minimum of 3 months (up to 6-12)
Other important Tx: Early ambulation for fully anti coagulated, hemodynamically stable pt Compression stockings (maybe)
Upper extremity DVTs
Can be spontaneous (1-4%) but usually secondary to catheter placement (ie - central line or pacemaker) or prothrombotic states
PE occurs in about 4-10% of UE DVTs
The most common cause of Pulmonary Embolism is _____
DVT
50-60% of proximal DVT will embolize
Isolated calf DVTs embolize much less frequently
Classifications of PE
- Presence or absence of hemodynamics stability
- Temporal pattern (acute, subacute, chronic)
- Anatomic location (saddle*, lobar, segmental, subsegmental)
- Presence or absence of symptoms
*Saddle = where pulmonary artery first bifurcates
Hemodynamic instability is defined as a systolic BP of ________ or a drop in systolic BP of _______________________.
Systolic <90 mmHg or drop of ≥40 mmHg from baseline for >15 min
Hemodynamically unstable patients are more likely to die from obstructive shock in the 1st two hours of presentation
SSx for Pulmonary Embolism
Range from asymptomatic to DEATH *Dyspnea (SOB) *Pleuritic pain *DVT Sx *Cough Tachypnea Tachycardia Decreased breath sounds Accentuated pulmonic component of the 2nd heart sound JVD
Evaluating for PE
BE SUSPICIOUS WITH ALL DVTs
ABCs (BP, HR, RR, mental status)
If hemodynamically stable, use combined clinical and pretest probability assessment (Wells for PE), D-dimer, and imaging (CT pulmonary angiogram)
If hemodynamically unstable, beside echo is safest to obtain presumptive Dx
Well’s criteria for PE
> 6 is a high probability of PE
\+3 for DVT Sx \+3 if other dx is less likely \+1.5 for HR>100 \+1.5 for immobilization ≥3 days \+1.5 for previous DVT/PE \+1 for he opts is \+1 for malignancy
Historical “gold standard” for PE
Pulmonary angiography
Highly specific and sensitive
Not used request Ly due to new generation of CTA scanning
Disadvantages:
Invasive, high IV contrast load, technically demanding, $$$
Test of choice for Dx of PE
CT-Pulmonary Angiography
Sensitive and specific
Accurate for the detection of large, main, lobar, and segmental PE
Less accurate for smaller, peripheral, subsegmental PE
Non-invasive
Contraindications:
IV contrast allergy, renal dysfunction
V/Q scanning
Sensitive test for PE but poorly specific due to high number of false positives (creates diagnostic challenge)
Most commonly used in patients with IV contrast allergies, renal dysfunction (sometimes pregnancies)
Best utilized in those with normal chest X-ray (difficult to differentiate from lung disease like COPD)
Classic EKG finding for PE
“S1Q3T3” pattern due to right ventricular strain
Chest X-ray findings for PE
Neither sensitive nor specific
Hampton’s hump = opacity due to infarct (tissue dying b/c not perfused
Western ark sign = oligemia (due to low blood flow)
PERC Rule
PE Rule-out Criteria
8 Criteria must ALL be negative to rule out PE: Age < 50 HR < 100 Oxyhemoglobin saturation ≥ 95% No Hemoptysis No estrogen use No prior DVT/PE No unilateral leg swelling No surgery/trauma within the past four weeks
If not all are No but probability still low, do a D-dimer
Treatment for PE
Supportive Care:
Supplemental O2
Intubation/mechanical ventilation if necessary
IV fluids or vasopressors
ANTICOAGULATION
Other possibilities: Thrombolytics IVC filter Thrombectomy/embolectomy Prophylactic measures
VTE Anticoagulants
For Acute Tx:
IV Unfractionated Heparin (UFH) - preferred for unstable pt or if rapid reversal is needed
SQ Low Molecular Weight Heparin (LMWH - Lovenox) - preferred for pregnancy and those with cancer
For long term use:
Oral Warfarin (Coumadin)
Factor Xa Inhibitors
• SQ formulation - Arixtra
• Oral - Xarelto, Eliquis, Savysa, Lixiana
Oral direct thrombin inhibitors (Pradaxa)
Transitioning from initial to long-term anticoagulation
Interruptions to tx should be minimized during the first 3 months due to high risk of recurrent thrombosis
Traditionally - long term therapy = warfarin
• monitor PT and INR (should be between 2-3)
• slow onset so must use 2nd agent until in system
• takes several days to reverse
Can also use oral factor Xa inhibitors or oral direct thrombin inhibitors
• depends on many factors
• consider if there are reversal agents or not
Anticoagulation reversal
UFH = protamine
LMW Heparin = protamine (but incomplete)
Warfarin = vitamin K (takes time) and fresh frozen plasma
Factor Xa inhibitors = Andexanet Alfa (EXPENSIVE)
Direct thrombin inhibitors = idarucizumab
Can also consider activated prothrombin complex concentrate (aPCC)
For all drugs —> discontinue drugs, transfuse blood if necessary, address hemorrhage anatomically.
Duration of anticoagulant therapy
Minimum of 3 months for first episode
If provoked (ie - identifiable risk factors) —> 3 months If unprovoked —> extended therapy (6-12 months) unless high bleed risk
Pt with a first or recurrent episode of unprovoked proximal DVT/unprovoked symptomatic PE can benefit from indefinite anticoagulation but consider underlying conditions
Testing for inherited thrombotic disorders and malignancy can ______________________, but does not __________________.
Can lead to the discovery of risk factors
Does not improve mortality
VTE before 45 years and at least one 1st degree relative with documented VTE should be tested for:
• All 5 inherited thrombotic disorders (antithrombin deficiency, protein S and C deficiences, factor V Leiden and prothrombin gene mutation)
-AND-
• Antiphospholipid syndrome
For what patients is a Vena Cava Filter indicated
- Anticoagulation is contraindicated
- Risk of bleeding is estimated to outweigh the risk of recurrent thromboembolism
- Recurrent PE despite adequate anticoagulation
- Complication of anticoagulation (severe bleeding)
- Hemodynamic or respiratory compromise
IVC filter prevents DVT from propagating to lungs
Thrombolytics
Activate plasminogen to form plasmin, resulting in the accelerated lysis of thrombi
Given in combo with anticoagulation
Used for UNSTABLE patients with PE (ie massive PE and sustained hypotension with cardiogenic shock)
Given peripherally (IV) or through catheter directed at the clot
Examples: Streptokinase, Urokinase, Recombinant tPA
Thrombectomy/Embolectomy
Mechanical device used to remove clots from veins quickly in order to restore normal venous flow, reduce Sx and prevent post-thrombophlebitic syndrome
Indicated in hemodynamically unstable PE for whom thrombolytic therapy is contraindicated
VTE prophylactic measures
Admitted pt with no risk factors - mechanical prophylaxis (ie TED hose or IPCs)
Admitted pt with one risk factor and no increased risk of bleeding —> pharmacological prophylaxis
• Low dose SQ LMWH (lovenox) 40 mg SQ daily
Admitted pt with multiple risk factors —> both mechanical and pharm prophylaxis
