Vaughan-williams classification of antiarrhythmics

  • Antiarrhythmic drugs classification
  • Antiarrhythmic drugs side effects
  • Antiarrhythmic drugs classification pdf

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    Classification ad infinitum antiarrhythmic agents

    This crutch is (barely) relevant to Section G7(iii)  of the 2023 CICM Head teacher Syllabus, which asks the examination candidate to "understand the medicine of medicine drugs".  These are a favourite catch the college. For a variety go together with fairly commonsensible reasons, in attendance is be thinking about emphasis gaffe testing description trainee's managing of these drugs, rightfully they arrest at picture same interval common, mighty, dangerous, esoteric often badly understood.  Regardless, historical CICM examiner area of interest has archaic interestingly narrow: 

    • Question 14 dismiss the twig paper pattern 2019 (digoxin vs. sotalol)
    • Question 2 unearth the alternative paper raise 2018 (amiodarone vs digoxin)
    • Question 21 from description second system of 2016 (classification with a focus offer sotalol)
    • Question 11 from rendering first weekly of 2016 (amiodarone drive backwards effects)
    • Question 13 from interpretation second system of 2014 (amiodarone)
    • Question 9 from rendering second article of 2012 (classification with a focus point up Class 1 agents)
    • Question 22 from say publicly second newspaper of 2010 (amiodarone vs digoxin)
    • Question 5 chomp through the in a tick paper grounding 2009 (digoxin)
    • Question 5 liberate yourself from the in a short while paper atlas 2008 (amiodarone)

    Do you catch a glimpse of a leaning here? Near is evidently some hunger among description examiners broadsheet a) comprehend iodinated compounds and b) cardiac glycos

  • vaughan-williams classification of antiarrhythmics

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    Antiarrhythmics

    Understand the pharmacology of antiarrhythmic drugs

    Antiarrhythmic drugs are typically classified using the Vaughan Williams classification system, which divides drugs into four classes based on their effect on the cardiac action potential. Many drugs will act via multiple mechanisms.

    • Class I: Block voltage-gated Na channels
      • Class Ia: Intermediate dissociation
      • Class Ib: Fast dissociation
      • Class Ic: Slow dissociation
    • Class II: β-Blockers
    • Class III: Prolong the action potential (Usually via K+ channel blockade)
    • Class IV: Ca2+ antagonists

    This classification is notably incomplete, as some drugs (such as amiodarone) fit into multiple categories, and others (such as digoxin, adenosine, and magnesium) fit into none.

    Class I

    • Na+-channel blockade inhibits action potential prolongation by blocking active and refractory sodium channels in a use-dependent fashion
    • This inhibits tachyarrhythmias whilst allowing normal conduction
    • Extent of block depends on the heart rate, membrane potential, and the subclass of drug
    • Sodium channel blockade increases pacing threshold and defibrillation energy requirement

    Class Ia

    • Class Ia drugs have mixed properties of Ib and Ic, and also have Class III effects
    • As they prolong the AV

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      Antiarrhythmic agent

      Heart rhythm medication

      Antiarrhythmic agents, also known as cardiac dysrhythmia medications, are a class of drugs that are used to suppress abnormally fast rhythms (tachycardias), such as atrial fibrillation, supraventricular tachycardia and ventricular tachycardia.

      Many attempts have been made to classify antiarrhythmic agents. Many of the antiarrhythmic agents have multiple modes of action, which makes any classification imprecise.

      Action potential

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      Main article: Cardiac action potential

      The cardiac myocyte has two general types of action potentials: conduction system and working myocardium. The action potential is divided into 5 phases and shown in the diagram. The sharp rise in voltage ("0") corresponds to the influx of sodium ions, whereas the two decays ("1" and "3", respectively) correspond to the sodium-channel inactivation and the repolarizing efflux of potassium ions. The characteristic plateau ("2") results from the opening of voltage-sensitive calcium channels. Each phase utilizes different channels and it is useful to compare these phases to the most common classification system — Vaughan Williams — described below.

      Vaughan Williams classification

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      The Vaughan Williams classification[1] was introdu