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Cardiac Action Potentials and Anti-Arrhythmic Drugs

Cardiac Action Potentials and Anti-Arrhythmic Drugs. Ca 2+ in (long). +10. K + out. Na + in (I f ) Ca2+ in (transient). -60. 4 K + (inwardly rectifying). 0 Na + FAST. 1 K + out. 2 Ca 2+ in (L-type) K + out (slow delayed). 3 K + out (slow & rapid delayed). 4

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Cardiac Action Potentials and Anti-Arrhythmic Drugs

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  1. Cardiac Action Potentials and Anti-Arrhythmic Drugs

  2. Ca2+ in (long) +10 K+ out Na+ in (If) Ca2+ in (transient) -60

  3. 4 K+ (inwardly rectifying) 0 Na+ FAST 1 K+out 2 Ca2+ in (L-type) K+ out (slow delayed) 3 K+ out (slow & rapid delayed) 4 Delayed close +52 -96

  4. Arrhythmia • Abnormal frequency, regularity or consistency of excitation and contraction of the heart • Common arrhythmias?

  5. Anti Arrhythmic Drugs • Classes 1-4 • “Some Block Potassium Channels” • I: Sodium Channel Blockers • II: Beta-Blockers • III: Potassium Channel Blockers • IV: Calcium Channel Blockers • Others…

  6. Class I – Na Channel Blockers • 1A: Lengthen action potential • Quinidine • 1B: Shorten action potential - Lidocaine • 1C: No shift - Flecainide

  7. Class II – Beta Blockers • Block effects of catecholamines • Act at β1-adrenergic receptors • Decrease sympathetic activity and AV node conduction • Indication: Tachycardias • Contra: Heart failure • Examples: Atenolol, propanolol

  8. Class III – K Channel Blockers • Prolong repolarisation (Phase 3) • Lengthen action potential • Indication: Re-entry arrythmias • Example: Amiodarone

  9. Class IV – Ca Channel Blockers • Block slow channels • Decrease AV node conduction and shorten plateau (Phase 2) • Contraindicated in HF • Examples: Verapamil, Diltiazem

  10. Others • Digoxin – negative chronotrope (decreases AV node conduction, increases vagal stimulation) • Adenosine – decreases AV node conduction

  11. Ca2+ in (long) +10 K+ out Na+ in (If) Ca2+ in (transient) -60 Ivabradine – Na Funny Channel Blocker

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