Arrythmias - Therapy Flashcards
(14 cards)
What is the Vaughan-Williams classification?
A system that categorizes anti-arrhythmic drugs based on their primary mechanism of action on cardiac ion channels and receptors.
What are the Classes of Vaughan-Williams classification?
Class I – Sodium channel blockers (affect depolarization)
Ia: Moderate block (e.g., quinidine, procainamide)
Ib: Weak block (e.g., lidocaine, mexiletine)
Ic: Strong block (e.g., flecainide, propafenone)
Class II – Beta-blockers (reduce sympathetic activity; e.g., atenolol, metoprolol)
Class III – Potassium channel blockers (prolong repolarization; e.g., amiodarone, sotalol)
Class IV – Calcium channel blockers (affect SA/AV node conduction; e.g., verapamil, diltiazem)
Are there other agents not fitting perfectly into Vaughan-Williams?
adenosine, digoxin, and magnesium sulfate aren’t classified but are used for arrhythmias.
Why is anticoagulant therapy important in arrhythmias?
Arrhythmias, especially atrial fibrillation (AF), cause turbulent blood flow, increasing the risk of blood clot formation and thus pulmonary embolism (PE) or stroke.
Which arrhythmia most commonly necessitates anticoagulation?
Atrial fibrillation (AF).
What guidelines are used to assess the need for anticoagulation?
CHA₂DS₂-VASc score (risk stratification for stroke) and HAS-BLED score (risk of bleeding).
What is Warfarin, and how does it work?
Warfarin is a vitamin K antagonist. It inhibits vitamin K epoxide reductase, reducing synthesis of clotting factors II, VII, IX, X, and anticoagulant proteins C and S.
What is the significance of Vitamin K in clotting?
Vitamin K is essential for the carboxylation (activation) of clotting factors needed for the coagulation cascade.
What is Heparin, and how does it act?
Heparin enhances the activity of antithrombin III, which inactivates thrombin (factor IIa) and factor Xa, preventing clot formation.
Difference between unfractionated heparin (UFH) and low molecular weight heparin (LMWH)?
UFH: Larger molecule, intravenous administration, needs aPTT monitoring.
LMWH (e.g., enoxaparin): Smaller fragments, subcutaneous injection, more predictable response.
What is SIGN?
Scottish Intercollegiate Guidelines Network – develops clinical guidelines based on evidence to improve patient care in Scotland, including recommendations on anticoagulation in arrhythmias.
How is Warfarin therapy monitored?
By measuring the INR (International Normalized Ratio).
Target INR: 2.0–3.0 in most cases of AF.
Name some newer anticoagulants (DOACs)?
Dabigatran (direct thrombin inhibitor), Apixaban, Rivaroxaban, Edoxaban (all direct factor Xa inhibitors).
