Antiarrhythmic Agents

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  1. phase 0
    • depolarization/upstroke
    • inward Na+ current (fast channel)
  2. phase 1
    • abrupt partial repolarization
    • decline in K+ channel
    • inactivation of fast Na+ channel
  3. phase 2
    • plateau or prolonged depolarization
    • slow inward Ca++ movement
    • slow inward Na+ movement (slow channel)
  4. phase 3
    • repolarization
    • slow inward channel (Na/Ca) closes
    • K+ opens (efflux)
  5. phase 4
  6. rate of arrhythmias may result from deviation from what aspects
    • site of origin
    • rate or regularity
    • conduction
  7. factors that exacerbate arrhythmias
    • ischemia
    • hypoxia
    • acidosis/alkalosis
  8. all arrhythmias result from disturbances in:
    • impulse formation (abnormal pacemaker)
    • impulse propagation
  9. ratio of atrial to ventrical firing in AF
  10. AF atrial rate
    280-300 bpm
  11. AF/VF can be characterized by
    reentrant impulse through atria or ventricles
  12. Sinus tachycardia firing rate
  13. PSVT firing rate
  14. torsades de pointes is characterized by
    varying amplitudes of the QRS complex along the baseline of EKG tracing
  15. VT rate
    series of 3 or more Ventricular extrasystoles at rates between 100 and 250 bpm
  16. class I MOA
    Na channel blockade
  17. class IA MOA
    • shortens phase 0 depolarization
    • intermediate acting
  18. class IB MOA
    • shortens phase 3 repolarization
    • prolongs phase 0 depolarization
    • quick acting
  19. class IC MOA
    slow phase 0 depolarization
  20. class II MOA
    • blockade of sympathetic autonomic effects
    • suppress phase 4 depolarization
  21. class III MOA
    prolongation of phase 3 repolarization
  22. class IV MOA
    calcium channel blockade
  23. class IA agents
    • procainamide
    • quinidine¬†
    • disopyramide
  24. unique features of procainamide
    • lupus like syndrome following chronic use
    • acetylated to NAPA with class III effect
  25. class IB drugs
    • lidocaine
    • mexiletine
    • phenytoin
  26. unique features of lidocaine
    • prototype
    • very safe
    • local anesthetic effect
  27. which drug is an analog of lidocaine
  28. type of effects of phenytoin
    antiepileptic effect
  29. class IC drugs
    • flecainide¬†
    • encainide
    • moricizine
    • propafenone
  30. class II agents
  31. adverse effects of b-blockers (three general mechanisms)
    B2 antagonism- bronchospasm, impotence, cold extremeties

    exaggeration of therapeutic effects of B1 antagonism (heart block, negative inotropism)

    drug penetration in CNS- insomnia, depression
  32. b-blocker used for the IV mgmt of acute arrhythmias that occur during surgery or emergency situation
  33. class III agents
    • ibutilide
    • dofetilide
    • sotalol
    • amiodarone
  34. which agent is a mixed class II and III agent
  35. class III agent that acts as I, II, III, IV agent
  36. how does amiodarone act at low and high doses
    one the most effective agents at low doses but has substantial toxicity at high doses or long periods
  37. class IV agents
  38. Class IV agents have little effect on
    Na+ fast channel dependent tissue such as purkinje fibers, atria and ventricles
  39. CCBs are used in the treatment of which type of arrhythmia
  40. verapamil and diltiazem are rarely used in the treatment of which ventricular arrhythmia
Card Set:
Antiarrhythmic Agents
2013-04-12 21:12:21
Dr Oyekan

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