11. Heme Disorders 2 Flashcards
Most important coagulation factor.
Thrombin
Component of the coagulation cascade that links the fibrin monomers that make up a clot.
Factor XII (Hageman Factor)
What does the Prothrombin Time (PT) assay assess?
The function of proteins in the extrinsic pathway of the coagulation cascade.
Factors: II, V, VII, X
How is a PT assay performed?
Calcium is administered to coagulation proteins and then the time for a clot to form is measured.
What does the Partial Thromboplastin Time (PTT) assay assess?
The function of protein in the instrisic pathway of the coagulation cascade.
Factors: II, V, VIII, IX, X, XI, XII
How is a PTT assay performed?
Ground glass is administered to coagulation proteins and its (-) charge activates Factor XII. Then time it takes to form a clot is then recorded.
Name the 3 categories of endogenous anticoagulants.
- Antithrombins (antithrombin III)
- Protein C and S (vitamin K-dependent)
- TFPI - inactivates tissue factor VIIa
3 abnormalities that lead to thrombus formation. (Virchow’s Triad)
- Endothelial Injury
- Stasis or turbulent blood flow
- Hypercoagulability of Blood
Major contributor to venous thrombi.
Stasis of blood flow
How do stasis and turbulent flow both contribute to thrombus formation?
Normal laminar flow keeps clotting factors and platelets in the center of the lumen of vessels. Stasis and turbulent flow cause margination of both component which interact with the endothelium causing a thrombus to form.
Alterations in the coagulation pathway that leads to hypercoagulability. Genetic Cause?
- Thrombophilia
2. Point mutation in Factor V gene
Condition in which the body produces antibodies to heparin and platelet levels drop because of the many thrombi that start to form.
Heparin-Induced Thrombocytopenia (HIT)
Condition with recurrent thrombus formation, repeated miscarriages, and cardiac vegetations due to auto-antibodies formed against endothelial phospholipids.
Antiphospholipid Antibody Syndrome (Lupus Anticoagulant syndrome)
Thrombus that grows retrograde from blood flow and forms at sites of turbulence.
Arterial Thrombi
Thrombus that extends in the direction of blood flow and occurs at sites of blood stasis.
Venous Thrombi
Platelet and Fibrin deposits located on vascular endothelium that indicate a thrombus formed ante-mortem (before death)
Lines of Zahn
Thrombi occurring in the heart chamber or aortic lumen.
Mural Thrombi
Frequently occlusive thrombus that is often superimposed on an atherosclerotic plaque.
Arterial Thrombus
Thrombus that is invariably occlusive that often forms in the lower extremities.
Venous Thrombus
Thrombi that form on heart valves usually as a result of blood-bourne bacteria or fungus.
Vegetations
Non-bacterial endocarditis often seen in SLE.
Libman-Sacks endocarditis
4 events a thrombus can go through in the days after its initial formation.
- Propagation - accumulation of platelets and fibrin
- Embolization - detachment
- Dissolution - fibrinolysis
- Organization and Recanalization
How does widespread microvascular thromboses lead to bleeding disorders?
The many microvascular thromboses cause platelet aggregation and usage of the coagulation factors. This depletes the body’s store of these components and then when fibrinolysis occurs there is excessive bleeding b/c no platelets or coagulation factors can stop it.
Detached intravascular solid, liquid, or gas.
Embolism
Where do most pulmonary emboli come from?
DVT in the lower extremities, usually above the knee.
Type of pulmonary embolism that can easily become lodged and cause sudden death.
Saddle embolism.
Name 3 causes of emboli.
- Hypercoagulability
- Immobilized pts.
- Heart Failure
Diagnostic characteristic on physical exam that a patient has a pulmonary embolism.
Absence of a pulse but a normal rhythm is seen on EKG.
Diagnostic of a pulmonary embolism on chest X-ray.
Hampton’s Hump
Major cause of fat emboli.
Broken long bones. (The fat in the bone marrow is released into circulation)
2 common clinical manisfestations of air emboli in scuba divers.
- The Bends - air emboli in skeletal muscle
2. The chokes - gas bubbles in vasculature
Chronic form of decompression sickness.
Caisson’s Disease
Cross contamination of mother’s blood with amniotic fluid causing an allergic reaction and possilbe death of the mother.
Amniotic Fluid Embolism
Classic findings in an amniotic fluid embolism.
Sqamous cells shed from fetal skin. (looks like a finger-print on histology slides)
Major clinical finding of shock.
Systemic Hypotension
How does the patient present with hypovolemic or cardiogenic shock?
Cool, clammy, cyanotic skin.
Weak rapid pulse, tachypnea
How does a patient present with septic shock?
Warm flushed skin usually due to peripheral vasodilation.
