1. Anti arrythmics
Dr Urmila M Aswar
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2. Anatomy of the conducting system
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3. Introduction
• Definition of Arrhythmia:
The Origin, Rate, Rhythm, Conduct
velocity and sequence of heart
activation are abnormal.
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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
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5. Pathogenesis and Inducement
of Arrhythmia
•
•
•
Pathological heart disease
Electrolyte disturbance and acid-base
imbalance
Physical and chemical factors or toxicosis
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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
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7. Impulse generation
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8. Reentry block
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9. Types: normal
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10. Sinus bradycardia
• HR< 60 bpm; every QRS
narrow, preceded by p
wave
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11. Sinus tachycardia
• HR > 100 bpm, regular
• Often difficult to
distinguish p and t
waves
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12. Sick sinus syndrome
• All result in
bradycardia
• Sinus bradycardia
(rate of ~43 bpm) with
a sinus pause
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13. PSVT
• Refers to
supraventricular
tachycardia
• Occur due to re-entry
• No P wave
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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.
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