Arrythmias

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Arrythmias

  1. 1. Anti arrythmics Dr Urmila M Aswar 1
  2. 2. Anatomy of the conducting system 2
  3. 3. Introduction • Definition of Arrhythmia: The Origin, Rate, Rhythm, Conduct velocity and sequence of heart activation are abnormal. 3
  4. 4. Phase 4: Resting/restoring with the Na+K+ pump; RMP is -90mV Phase 0: Depolarization; Influx of Na+ through FAST Na+ channels Phase 1: Early Rapid Repolarization: K+ efflux, Fast Na+ channels close Phase 2: Slow Repolarization (plateau phase): K+ efflux, influx of Ca++ and Na+ (SLOW Na+ channels) Phase 3: Final Rapid Repolarization: K+ efflux, Ca++ and SLOW Na+ channels close 4
  5. 5. Pathogenesis and Inducement of Arrhythmia • • • Pathological heart disease Electrolyte disturbance and acid-base imbalance Physical and chemical factors or toxicosis 5
  6. 6. Mechanism of Arrhythmia • 1. 2. a. b. Abnormal impulse formation Ectopic pulse After depolarization's Early after depolarization Delayed after depolarization-triggered arrythmia • Abnormal impulse conduction 1. Reentry eg Afl, PSVT 2. Conduct block eg sick sinus 6
  7. 7. Impulse generation 7
  8. 8. Reentry block 8
  9. 9. Types: normal 9
  10. 10. Sinus bradycardia • HR< 60 bpm; every QRS narrow, preceded by p wave 10
  11. 11. Sinus tachycardia • HR > 100 bpm, regular • Often difficult to distinguish p and t waves 11
  12. 12. Sick sinus syndrome • All result in bradycardia • Sinus bradycardia (rate of ~43 bpm) with a sinus pause 12
  13. 13. PSVT • Refers to supraventricular tachycardia • Occur due to re-entry • No P wave 13
  14. 14. Classes of antiarrythmic agents • Classification of antiarrhythmic agents: • Class I agents interfere/ blocks the sodium (Na+) channel. • Class II agents are anti-sympathetic nervous system agents. Most agents in this class are beta blockers. • Class III agents affect potassium (K+) efflux/ K blockers. • Class IV agents affect calcium channels/ Ca channel blockers • Class V agents work by other or unknown mechanisms. 14

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