Clotting Disorders VTE Flashcards
What is hemostasis
Process to stop bleeding at the site of vascualr injery through complex interactions between vascular endothelium, platelets, procoagulant proteins, anticoagulant proteins and fibrinolytic proteins
What are the three key mechanisms that facilitate hemostasis
Vascular constriction, primary platelet plug formation (primary hemostasis), clot propagation through fibrin formation (secondary hemostasis)
What is the basic four step mechanism for platelet aggregation when injury occurs
Platelets first adhere to macro molecules in the sub-endothelial regions of the injured blood vessel, platelets activate, adherent platelents release substances that activate nearby platelets and recruit them, activated platelets then aggregate to form the primary hemostatic plug
What protein initiates the coagulation system when exposed due to vessel wall injury
Tissue factor
Which thrombin factor is usually seen in this coagulation, what does it do
Thrombin (factor IIa), thrombin converts fibrinogen to fibrin reinforcing the platelet aggregation and anchors it to the vessel wall
T/F:The extrinsic and intrinsic pathway both convert into the common pathway for coagulation leading to more thrombin
True
What are the natural inhibitors of the coagulation cascade
Antithrombin III, Protein C, Protein S
What is the most common defect in the natural coagulant system, what occurs
Factor V leiden, mutation in factor V that results in resitance to inactivation by protein C and protein S
What is thrombosis
Formation of an inappropriate fibrin-platelet aggregate
Where are sites thrombosis can take place
Endothelium of blood or lymphatic vessels (mural thrombus) , within the heart (cardiac thrombus), free in blood or lymphatic vessels (thromboembolus)
What is venous thromboembolism, what are two types
Clot formation within the venous circulation, DVT and pulmonary embolism
Where do most DVTs take place
The proximal veins (Deep femoral vein and superficial femoral vein)
What is the order of pulmonary embolism types from most dangerous to least dangerous
Saddle embolism, lobar embolism, segmental, subsegmental
What guide is used to assess risk for ischemic stroke, what are its parameters
CHADS2/ Congestive heart Failure, Hypertension, Age greater than 75, Diabetes, Stroke or Trans ischemic attack
T/F: On the CHADS2 score each category is worth one point
False: On the CHADS2 score each category is worth one point except Stroke or TIA, which is worth 2 points