Pathophysiology of VTE Flashcards
VTE stands for…
Venous Thromboembolism
VTE most commonly presents as these two forms…
Deep vein thrombosis (DVT) - 2/3
Pulmonary embolism (PE) - 1/3
A venous thrombus differs from an arterial thrombus by the following…
Formed without damaging the vessel wall; held together by mostly fibrin, NOT platelets
VTE results from…
Also where does it mainly develop?
Clot formation within the venous circulation
Mainly develops in lower extremities, in calf veins
Minority in arm, brain, GI, liver
The venous thrombus from VTE may result in…
Obstruction of venous circulation - ischemia
Embolize - travel through bloodstream
Lyse - no symptoms
The two pathways involved in the coagulation cascade are…
The intrinsic pathway (damaged surfaces) and extrinsic pathways (external trauma)
The three factors that are exclusive to the intrinsic pathway are…
12, 11, and 9
The one factor exclusive to the extrinsic pathway is…
7
____ converts factor 9a in the intrinsic pathway to factor 10.
8a
____ converts factor 7a in the extrinsic pathway, to factor 10.
Tissue factor
The factor that is activated by both intrinsic and extrinsic pathways is…
Factor 10 - activated by 9a, and 7a
Factor 10a, combined with 5a, furthers the coagulation cascade by…
What does it help convert? There are two more steps in common pathway
Converting prothrombin (2) to thrombin (2a), which causes fibrinogen (1) to convert to fibrin (1a)
RESULTING in fibrin clot
Risk factors for VTE are also known as…
Virchow’s Triad
The three components in Virchow’s Triad are…
Venostasis
Vessel wall injury
Hypercoagulability
Venostasis can be aggravated by the following:
Virchow’s
Prolonged bedrest/immobility
Heart failure (class 3-4)
Atrial fibrilation
Vascular damage can be caused by…
Virchow’s
Previous VTE
Bacterial infection - sepsis
Trauma - surgery, implants
Peripheral vascular disease
Hypercoaguability can be increased by…
Virchow’s - both inherited and adjustable factors
Medications
Malignancy
Inherited thrombophilias
Pregnancy + Post-partum
Increased age, obesity, smoking
Some medications that may increase hypercoagubaility are…
Estrogen - birth control
SERMS, chemotherapy
Older antipsychotics
Erythropoietin
Symptoms of a DVT often include…
Leg related
Leg pain + tenderness
Ankle edema and calf swelling
Dilated veins
Dusky discolouration
These symptoms can be seen in other conditions as well; statin use
Symptoms of a PE often include…
Chest related
Sense of impending doom
Sudden, unexplained SoB, tachypnea, tachycardia
Chest pain, cough
Hemoptysis, fever, cyanosis
Post-thrombotic syndrome (PTS) is a complication of DVT, where the patient may experience…
Chronic pain, swelling + edema, fatigue, and leg ulcers
A possible treatment that may help with post-thrombotic syndrome is…
However, cannot be used in…
Compression stockings - ankle to knee, at onset of DVT
CI with ulcers, HF, derm issues, peripheral neuropathy
Venous skin ulcers may result as a complication of VTE, due to…
Lack of proper blood flow - pooling of blood
Chronic thromboembolic pulmonary hypertension may occur as a complication of a PE, which results in…
What medication do they have to be on for life?
Scarring of lungs - narrowing of arteries and permanent increase in pulmonary blood pressure, may lead to right-sided heart failure
Anti-coagulation necessary for life
A lab value that can help rule in VTE is an increase in…
D-Dimer
To predict likelihood of DVT or PE, we can use…
The Wells Criteria
Imaging that can help diagnose VTE include…
Compression ultrasonography
CT scan
Ventilation/perfusion scan
A goal of treatment that should take priority when considering VTE is…
Prevention of initial VTE
Other goals of treatment that should be considered, besides initial prevention, include…
Resolution of signs and symptoms of VTE
Prevention of extension (DVT to PE)
Prevent hemodynamic collapse or development of complications
Prevent recurrence of VTE
Reduce risk of adverse effects from drug treatment
A big challenge of preventing and treating VTE is to balance…
Bleed risk vs. clot risk - bleeding is predominant adverse event
Monitoring is key
Bleeding rates tend to increase with…
Drug-related
Intensity and duration of therapy
aPTT measures…
What drug does it test
Intrinsic + common pathways of coagulation - longer time = less clotting
Tests heparin
PT measures…
What drug does it test
Extrinsic and common pathway of coagulation
Heparin
PTT differs from aPTT, because…
aPTT uses an activator to speed up clotting time, creating a narrower reference range (more sensitive)
Anti-Xa tests are used to test efficacy of…
LMWH and heparin
INR measures anticoagulant activity of…
Warfarin
INR is calculated with PT, corrected for lab variation
