Venous Thrombembolism Flashcards
What is the mortality rate for VTE?
Venous Thromboembolism is a major cause of morbidity and mortaliity (10% of hospital deaths due to pulmonary embolism)
More than death by breast cancer, HIV, and motor vehicle accidents
Is VTE treatment or prophylaxis the same as atrial fibrillation or secondary prevention of MI/Stroke?
No, they use different therapeutic agents
What are some characteristics of venous circulation?
- Return blood to heart for re-oxygenation
- Thinner walls vs arteries
- Elastic (variably widens as blood passes through)
- Lower shear rate than arteries
- One-way valves close to prevent backflow (damage can cause blood to pool)
What is the pathophysiology of venous thrombus (red clot)?
- Formed without damaging vessel wall
- Held together by mostly fibrin, less platelet
- Leads to VTE (DVT/PE)
What is the pathophysiology of arterial thrombus (white clot)?
- Formed from rupture of atherosclerotic plaque
- Held together by mostly platelet, less fibrin
- Leads to ACS, stroke, or peripheral arterial disease (PAD)
What is the definition of venous thromboembolism?
Results from clot formatrion within venous circulation
What causes venous thromboembolism to develop from a venous thrombus?
A venous thrombus (clot) may have the following:
- Lyse
- Obstruct venous circulation
- Embolize
- Combination
Where do thromboembolisms usually form?
Mainly in the lower extremities
Majority in calf veins, minority in arm, brain, GI tract, liver
What is the physiology of coagulation?
Generation of thrombin (factor 2a) is central to the coagulation cascade
Thrombin is made from prothrombin by factor 10a
Prothrombin –> Thrombin –> Fibrinogen –> Fibrin clot
What are the three main categories of risk factors for VTE?
- Stasis
- Vessel wall injury
- Hypercoagulability
What are some causes for circulatory stasis?
- Bed rest/immobility (often seen in hospitalization)
- Heart failure (Class III-IV)
- Varicose veins (maybe)
- Atrial fibrilation
What are some causes for vascular damage?
- Previous VTE
- Bacterial infection (sepsis)
- Prosthetic implants
- Peripheral vascular disease
- Trauma
- Surgery (especially following hip and knee replacements)
What are some causes of hypercoagulability?
- Medications
- Use of oral contraceptives
- Malignancy
- Inherited thrombophilias
- Advanced age (over 60)
- Obesity (BMI over 30)
- Protein C or S deficiency
- Smoking
What is the risk of getting VTE during pregnancy/post-partum?
Pregnancy (5-10x increase during pregnancy)
Early post-partum (15-35x increase)
What are some specific drug related increases in rates of VTE?
- Estrogen (2x risk vs. baseline)
- SERMS (Tamoxifen/raloxifen)
- Chemotherapy
- Older antipsychotics
- Erythropoietin
What are some signs and symptoms associated with VTE?
Often asymptomatic, and symptoms manifest as the clot get larger
Non-specific symptoms:
Leg pain (90%)
Tenderness (85%)
Ankle edema (76%)
Calf swelling (42%)
What are some signs and symptoms associated with pulmonary embolisms?
Symptoms of PE
- Sudden, unexplained SOB
- Tachypnea
- Tachycardia
- Cough
- Cyanosis
Are the recurrance rates associated with VTE low?
No, a large (as high as 7%) portion of people who have experienced a VTE will have a VTE more than once
What are some complications associated with VTE?
- Recurrent VTE
- Post-thrombotic syndroms
- Venous ulcers, chronic thromboembolism, pulmonary hypertension(CTEPH)
What is post-thrombotis syndrome (PTS)?
It develops in 10-50% of patients that have DVT and will develop within 3-6 months
What are some treatment options for post-thrombic syndrome?
Compression stockings (avoid if patient has lesions on legs)
30-45mgHg at ankle following DVT diagnosis
What causes skin ulcers following VTE?
They are caused by venous insufficiency, leading to pooling blood
Venous insufficiency is also a major cause of chronic wounds as they take longer to heal
What is chronic thromboembolic pulmonary hypertension (PTS)?
Following a PE
Scarring in the lungs causes arteries to narrow in the lungs. This leads to a permanent increase in pulmonary blood pressure (may lead to right-sided heart failure)
Need to be anti-coagulated for life after treatment
How is VTE diagnosed?
Lab tests:
- D-dimer increase
- ESR and WBC count increase
Clinical prediction score:
- Wells criteria (DVT & PE)
Imaging:
- Compression ultrasonography
- CT scan
- Ventilation/perfusion scan