Venous Thromboembolism Flashcards
What are the most common presentations of venous thrombosis?
Deep vein thrombosis or pulmonary embolism
What is Virchow’s triad?
Stasis (alterations in blood flow so that the blood is sitting there ready to coagulate), vessel wall injury and hypercoagulability (alterations in constituents of blood either inherited or acquired) cause thrombosis
What is a MAJOR risk factor for recurrent VTE?
Previous thrombotic event
Chronic conditions that are acquired risk factors of VTE
Malignancy, antiphospholipid antibody syndrome, myeloproliferative disorders
Chronic diseases, obesity, advanced age, smoking
Transient states that are acquired risk factors of VTE
Surgery, trauma, immobilization
Female specific acquired risk factors of VTE
Pregnancy, hormonal contraceptives
Inherited risk factors of VTE
Factor V Leiden mutation of prothrombin gene mutation
What are the classic symptoms of a DVT?
Swelling, pain and erythema of the involved extremity
What is the most useful finding for a DVT?
Larger calf diameter
Wells scoring for DVT
Paralysis/orthopedic casting Bedridden/major surgery within 4 wks Localized tenderness Swelling of leg Calf swelling Pitting edema Collateral non varicose superficial veins Active cancer/ or last 6 mos Alternate diagnosis more likely (-2)
What do you do after calculating pretest probability and they have a low or moderate probability of a DVT?
Do a serum D-dimer
What is a serum D-dimer?
Degradation product of cross-linked fibrin (clots)
Detectable at levels higher than 500 ng/mL in almost all VTE pts (use ELISA)
Sensitive but not specific for DVT so only useful when NEGATIVE (and low probability because then they don’t have it)
What are the other diagnostic tests for DVT?
Contrast venography
Impedance plethysmography
Compression ultrasound**
What do you see on compression ultrasound in a DVT?
Loss of vein compressibility because the clot is in the way
Doppler assesses blood flow to the given region
When do you need to treat a DVT?
Always for proximal DVTs (popliteal, femoral, iliac) because secondary to risk of PE and death
Appropriate for many distal DVTs especially when they have sxs
What is the purpose of DVT treatment?
Prevent further clot propagation
Prevent PE
Decrease risk of recurrent VTE
Decrease complications (post-thrombophlebitic syndrome caused by chronic venous insufficiency)
What is the mainstay of DVT therapy?
Anticoagulation
Initial anticoagulation therapy for DVT
0-10 days is the period of highest risk for recurrent thrombosis or embolization so this tx is for that
What is the minimum amt of time for anticoagulation therapy?
3 months (long term but finite)
What else is recommended in the tx of DVT?
Early ambulation for fully anticoagulated, hemodynamically stable and pts whose sxs are under control
What are elastic graduated compression stockings used for?
Prevention of post thrombotic syndrome
Causes of upper extremity DVT
Spontaneous
Secondary (more common) to catheter placement of prothrombotic states
What is superficial thrombophlebitis?
Not a DVT but usually caused by a peripherally inserted IV into a small vein
Tx with local heat and NSAIDs and usually goes away in 1-2 wks
What material can cause a pulmonary embolism?
Thrombus, tumor, air or fat
What is the most common cause of pulmonary embolism?
DVT (mostly proximal, isolated calf DVT is much less frequent)
How are PEs classified?
Presence or absence of hemodynamic stability (is it causing severe vascular problems?)
Temporal pattern of presentation (acute, subacute or chronic)
Anatomic location (saddle-where pulm Ar splits, lobar, segmental, subsegmental)
Presence or absence of sxs
What is another name for a hemodynamically instable PE?
Massive PE!
Systolic BP <90 mmHg or drop of SBP of over 40 from baseline for more than 15 min
Common symptoms of PE
Dyspnea, pleuritic pain, cough and sxs of a DVT
Also tachypnea and dacycardia
What is the difference in diagnosis between hemodynamically stable and unstable pts?
Stable: Wells criteria, D-dimer and CTPA
Unstable: cannot do definitive imaging so need bedside echocardiography to get presumptive diagnosis (see a collapse/abnormality of right ventricle)
What is the test of choice for diagnosis of a PE?
CT pulmonary angiogram
What are additional tests for PE?
VQ scan, contrast pulm angiography, serial lower extremity u/s, magnetic resonance pulm angiography
When is CT pulmonary angiography most accurate?
For detection of large, main, lobar and segmental PEs
When can you not use CTPA?
IV contrast allergy or renal dysfunction
VQ scanning
Sensitive test for PE but poorly specific because of false-positives
Can be interpreted as “intermediate probablity” and then you can’t do much with that
Most commonly used when pts can’t do CTPA
When is VQ scanning easiest to interpret?
When pt has a normal chest radiograph
What is the most common findings/classic finding of PE?
Nonspecific ST-segment and T wave changes
Classic: S1Q3T3 pattern with right ventricular strain
What can you see on a chest x ray in PE?
Hamptom’s hump: opacity from infarct
Westermark sign: oligemia (low BF)
What is the PERC rule?
PE rule out criteria as alternate to further testing in low prob assesment for PE
Age <50, HR<100, oxyhemoglobin saturation >95, no hemoptysis, no estrogen use, no prior DVT/PE, no unilateral leg swelling, no surgery/trauma with hospitalization in last 4 weeks
If fulfill all 8, no further testing
What is the treatment for PE?
Supportive: supplement O2, mechanical ventilation if needed, vasopressors to maintain BP
Anticoagulation
And other things
What are the options for VTE anticoagulants?
IV unfractionated heparin (not usually for a stable person)
SQ LMWH (Lovenox)
Oral Warfarin (Coumadin)
Factor Xa inhibitors (fondspusrinux-Arixtra, Xarelto, Eliquis, Savaysa, Lixiana)
Oral direct thrombin inhibitors (Pradaxa)
What anticoagulant is best for pts with renal failure, hemodynamically instability or massive iliofemoral DVT?
IV UFH (because need rapid reversal)
What is the anticoagulant of choice in pregnancy or active cancer?
LMWH
Why do you not want to interrupt tx in the first 3 months?
There is a high risk of recurrent thrombosis
What is the traditional long term therapy?
Warfarin (monitor with prothrombin time and international normalized ratio)
What are the best choices for tx when the patient does not want to do INR monitoring?
Oral factor Xa inhibitors and oral direct thrombin inhibitors
What is the anticoagulation reversal for UFH?
Protamine
What is the anticoagulation reversal for LMWH?
Protamine (usually incomplete reversal tho)
What is the anticoagulation reversal for warfarin?
Vitamin K and fresh frozen plasma
What is the anticoagulation reversal for factor Xa inhibitors?
Andexanet alfa
What is the anticoagulation reversal for direct thrombin inhibitor?
Dabigatran (idarucizumab)
What are some general anticoagulation reversals?
Activated prothrombin complex concentrate, antifibrinolytic agents (transexamic acid), hemodialysis, activated charcoal
What is the duration of therapy for an unprovoked clot?
Extended unless high risk of bleeding (6-12 mos)
When do you consider indefinite anticoagulation?
Pts with underlying thrombophilia or active malignancy
What should people with a VTE before 45 and have at least one 1 degree relative with a VTE be tested for?
All 5 inherited thrombotic disorders (antithrombin def, protein s and c def, factor V leiden and prothrombin gene mutation)
AND
Antiphospholipid syndrome
When would you consider and IVC filter?
Anti coagulation is contraindicated
Risk of bleeding outweighs risk of recurrent VTE
Recurrent PE despite adequate anticoagulation
Complication of anticoagulation like severe bleeding
Hemodynamic or respiratory compromise so that another PE may be life threatening
What do thrombolytics do?
Activate plasminogen to form plasmin which results in an accelerated lysis of the thrombi- clot buster
BUT it might burst arteries in the brain
When are thrombolytics indicated?
Unstable pt with a PE (massive PE and sustained hypotension with cardiogenic shock)
When do you use thromectomy/embolectomy?
Hemodynamically unstable PE when thrombolytic therapy is contraindicated or they failed thrombolysis
What is another helpful VTE deterrent?
Early ambulation
What are some mechanical prophylactic measures for hospitalized pts?
Intermittent pneumatic compression and thromboembolitic deterrent hose
What prophylatic measures are used in admitted pts with no risk factors?
Mechanical prophylaxis
What prophylatic measures are used in admitted pts with 1 risk factor and no increased risk of bleeding?
Pharmacological prophylaxis- low dose subQ heparin (Lovenox) at 40 mg a day
What prophylatic measures are used in admitted pts with multiple risk factors for VTE?
Mechanical and pharmacological prophylaxis
What must a pt be able to do if they are not admitted for their tx of a VTE?
Have their pain controlled
Be able to administer injections if needed
Have the ability to pay for injections when transitioning to oral warfarin
Be compliant