Thrombogenesis and Hemostasis Quiz

Thrombogenesis

• Formation of blood clots depends on hemostasis, endothelial function, platelets, and coagulation factors.
• Optimal body function is crucial for proper clot formation
• Improper function impacts clot formation.
• Platelets cause red blood cells to stick together.
• Increased platelets lead to more frequent clotting.
• Decreased platelets lead to more frequent bleeding
• Coagulation factors (factors II, VII, IX, X, XI, XII) come from the liver.

Hemostasis

• Maintenance of the vascular system.
• The body breaks down clots (thrombolysis)
• Plasminogen (from the liver), forms with the clot and helps the clot breakdown
• Clots are formed and broken down constantly.

Clot Lysis (Thrombolysis)

• The body's process of breaking up blood clots.
• Plasminogen forms with the clot, but once complete, plasmin is produced to help breakdown the clot.
• Clots are constantly being formed and broken down.

Types of Clots

• Arterial: Associated with atherosclerosis, heart attacks, and strokes (95% of strokes are clot related)
• Venous: Such as deep vein thrombosis (DVT)

Atherosclerosis

• A discussion of the pathophysiology is included in the document.

Anticoag Drugs (Heparin)

• Short-acting anticoagulant, commonly used in hospitals for preventative measures.
• Body produces its own anticoagulants (liver and lungs)
• Sometimes body's own coagulation is not enough.
• Given SQ or IV; not absorbed through the GI tract.
• Combines with antithrombin III to inactivate factors IX, X, XI, XII.
• Inhibits clot formation after initial clot formation.
• Does not typically break down clots that have already formed
• Can be used prophylactically (preventatively), especially prior to surgeries (orthopedic).
• Side effects include hemorrhage (internal bleeding).
• Monitor aPTT (activated partial thromboplastin time); goal is a value 2-3 times the normal value (25-30 seconds)

Drug Interactions

• Interactions with other drugs (e.g., antibiotics like cephalosporins, penicillins) and conditions (e.g., hemophilia) are indicated and should be noted. Avoid grapefruit.

Monitoring

• Activated Partial Thromboplastin Time (aPTT) is used to monitor heparin's effectiveness by measuring how long it takes blood to clot.
• Normal aPTT is between 25-30 seconds.
• With heparin, aPTT should be 2 to 3 times longer.

Protamine Sulfate

• An antidote for heparin overdose, if too much heparin is administered.

Direct Factor Xa Inhibitors

• A class of medications that inhibit factor Xa, preventing clot formation.
• Examples include apixaban and rivaroxaban.

Anticoagulants (Warfarin/Coumadin)

• Warfarin interferes with Vitamin K clotting factors (factors II, VII, IX, X)
• Monitoring INR (International Normalized Ratio) is critical
• INR values should fall within a reference range 2-3
• Vitamin K is an antidote to warfarin.
• Side effects: bleeding

Monitoring for Warfarin

• INR (international normalized ratio) values should be monitored.

Antiplatelet Drugs

• Prevent steps in the prothrombotic activity.
• Examples include Clopidogrel (Plavix).

Antiplatelet Activity

• Clopidogrel (Plavix) is an example of a medication that can prevent blood clotting by irreversibly blocking ADP receptors on platelets.

Dyslipidemia

• Cholesterol, triglycerides, and other lipids in the blood.
• Elevated cholesterol and triglycerides contribute to conditions like atherosclerosis.
• Different types of lipids include total cholesterol, HDL ("good" cholesterol), LDL ("bad" cholesterol), and triglycerides.
• Management can involve lifestyle changes (diet, exercise) and medications.

HMG-CoA Reductase Inhibitors (Statins)

• Reduce total, LDL, VLDL, and triglycerides; slightly raise HDL, which is beneficial.
• Examples include Atorvastatin (Lipitor).
• First pass effect in the liver, lowers drug availability in the blood.

Bile Acid Sequestrants

• Cholestyramine (Questran) binds to cholesterol in the intestine, preventing its absorption, and promoting its excretion in the stool.
• Side effects may include GI issues.

Fibrates

• Fenofibrate (tricor) increases the oxidation of fatty acids, decreasing hepatic production of cholesterol, LDL, triglycerides and increases HDL, used for high triglycerides.
• Side effects may include GI issues and gallstones.