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Flashcards in 1 - Bleeding Deck (48):

What is the second most numerous cell in the bloodstream, and how often is it replaced by the body?

Platelets - every 10 days


Where are clotting factors synthesized?

In the liver


What is necessary for the synthesis of 4 clotting factors? What are they?

Vitamin K

Factors II, VII, IX, X

Protein C and S


What is heparin primarily secreted by?

  • Mast cells & basophils


Where do clots on the left and right side lodge?

  • Left side of body
    • Blocks arterioles - ischemia to organs
  • Right side of body
    • Pulmonary arteries to lungs - pulmonary embolism (PE)


Why is bacterial endocarditis treated with both antibiotics and anticoagulants?

Because circulating bacteria and their endotoxins activate clotting = septic shock


What are the clotting cascade steps?

  • Prothrombin
  • Thrombin
  • Fibrinogen
  • Fibrin


What is the leading cause of re-hospitalization following joint replacement surgery?

Deep vein thrombosis and Pulmonary embolism


What are anti-platelet drugs used for?

  • To reduce the risk of stroke and other adverse thromboembolic events


What is a percutaneous coronary intervention (PCI)?

Stent - bare-metal and drug-eluting stents

Optimal treatment for many patients experiencing acute coronary syndromes


Aspirin along with antiplatelets do what to platelets?

Cause irreversible effects


What is the most comprehensively studied and least expensive of all antiplatelet medications?

Aspirin - acetylsalicyclic acid (ASA)


In dentistry - what is the drug for MI treatment for patients having a heart attack for pre-hospital admission?

Aspirin - 325 mg full strength, 81 mg low dose


If there is a well-documented and justifiable need to discontinue aspirin before dental treatment, wait at least ______ prior to invasive surgical procedures.

1 week -  it allows for platelet turnover


What does discontinuing the use of aspirin suddenly do?

Increases mortality risk - 3 fold higher risk 

Even higher in pts with coronary stents - by a factor of 89


What older antiplatelet drug can be used with warfarin to decrease thrombosis following placement of artificial heart valves?

dipyridamole (Persantine)


What antiplatelet drugs fall under the category of Theinopyridines?

  • ticlopidine (Ticlid)
  • clopidogrel (Plavix)
  • prasugrel (Effient) - new drug in 2009


What drug is used for those who are intolerant to aspirin, and coronary stent implantation has taken place?

ticlopidine (Ticlid)

- lowers risk of stent thrombosis


What drug prevents the binding of ADP to collagen receptors which prevents platelet aggregation?

clopidogrel (Plavix)

- Replaced use of ticlopidine, better safety-tolerance profile


What are the indications for clopidogrel (Plavix)?

  • Reduce rate of TE (MI, stroke, vascular death) in pts with recent MI or stroke
  • Reduce rate of TE in pts with unstable angina managed medically or with PCI


What is the main course of action of theinopyridines?

Inhibit the ability of adenosine diphosphate (ADP_ to induce platelet aggregation -- irreversible effect


What is the US boxed warning on prasugrel (Effient)?

May cause significant or fatal bleeding - contraindicated in pts with active pathological bleeding or history of TIA or stroke.


What are the 3 recommendations from advisory statement concerning disconinuation of anti-platelets?

  1. Consult cardiologist to discuss optimal pt management strategies
  2. Elective procedures with risk of bleeding should be deferred until pt has completed appropriate course of thienopyridine therapy
    1. 12 months after DES implant (stent)
    2. Minimun 1 month for bare-metal stent
  3. Pts with DES who have procedures, aspirin should be continued - restart thienopyridine asap


What are platelet glycoprotein IIb/IIIa receptor antagonists (fibrinogen receptor inhibitors) used for?

Used with aspirin and heparin to treat acute coronary syndromes via IV infusion


What are the platelet glycoprotein IIb/IIIa receptor antagonists (fibrinogen receptor inhibitors)?

  • abciximab (ReoPro)
  • eptifibatide (Integrilin)
  • tirofiban (Aggrastat) - most widely prescribed


In the pathway for platelet adhesion, where do platelet glycoprotein IIb/IIIa receptor antagonists (fibrinogen receptor inhibitors) act?

Final common pathway - inhibits binding of fibrinogen, von Willebrand factor and other adhesives to form platelet aggregation


What kind of effect do NSAIDS have on platelets?



What is the US boxed warning on NSAIDS?

They are associated with an increased risk of adverse cardiovascular thrombotic events, including fatal MI or stroke


From FDA advisory statement - "ibuprofen can interfere with the anti-platelet effect of low dose _______ (___ mg per day), potentially rendering _______ less effective when used for cardioprotection and stroke prevention."

  1. aspirin
  2. 81 
  3. aspirin


What should pts do if they had to take ibuprofen with aspirin?

Ibuprofen at least 30 minutes or longer after aspirin ingestion, or more than 8 hours before aspirin ingestion.


What are the antithrombins along with their indications?

  • Antithrombin III - antithrombin III deficiency
  • Heparin - enhances inhibition rate of clotting proteases by antithrombin III
  • Low molecular weight heparins - prevention/treatment of thromboembolic disorders


How does heparin work?

Inactivation or thrombin - final common pathway


What is the antidote to heparin?



What are the common low molecular weight heparins and what is it's use?

Used to prevent DVT with or withour PE, acute unstable angine

  • dalteparin (Fragmin)
  • enoxaparin (Lovenox)
  • tinzaparin (Innohep)


What is an oral anticoagulant that interferes with liver synthesis of vitamin-K dependent clotting factors?

warfarin (Coumadin, Jantoven)


What are some important indications for taking warfarin (Coumadin)?

  • Atrial fibrillation
  • Cardiac valve replacement
  • Adjunct to reduce risk of systemic embolism after MI
    • Takes about 4-5 days for effects


Drugs that induce liver metabolism will do what to the level of warfarin?

Decrease it - it's metabolized by P450 enzymes


What can upsest a pts level of anticoagulation from warfarin?

  • Leafy greens - vitamin K intake
  • Fever
  • Flu
  • Diarrhea or vomiting


What are some dental implications with warfarin?

  • Increased gingival bleeding and mouth ulcers
  • No need to discontinue warfarin prior to routine dental procedures


What is activated partial prothrombin time (aPTT) used to measure?

The effects of heparin, which increases aPTT to 50-70 seconds


What is used to measure the effect of warfarin?

International normalized ratio (INR)


What is the therapeutic INR range for pts with venous thrombosis, embolisms and atrial fibrillation? And the therapeutic INR range for mechanical prosthetic heart valves?

  1. INR = 2.0 - 3.0
  2. INR = 2.5 - 3.5 for prosthetic heart valves


What is the significant dental drug interaction with warfarin?

acetaminophen (Tylenol) - enhances anticoagulation 10 fold 


What causes the greatest number of drug interactions?

warfarin (Coumadin, Jantoven) 

**Always ask about the INR and monitor INR status across time ***


What is dabigatran (Pradaxa)?

Thrombin inhibitor - FDA approved Oct 2010

  • Prevents stroke and systemic embolism in pts with atrial fibrillation


What are the advantages and disadvantages of dabigatran compared to warfarin?

  • Advantages
    • No monthly monitoring, less interactions
  • Disadvantages
    • Expensive, twice daily dosing, bleeding, GI effects


What is the first and only oral anticoagulant approved in US for orthopedic surgery?

rivaroxaban (Xarelto) - prevents DVT following hip replacement


What are the main Clot-Busting drugs and when are they used?

Used within hours of adverse embolic event 

  • tPA (tissue plasminogen activator) - IV drug
  • streptokinase (Streptase)
  • urokinase