Cardiac Rhythm Disorders

Chapter 9:   Antiarrhythmic Agents

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Electrophysiology and Cardiac Arrhythmias

Cardiac Electrophysiology

Cardiac Cell Phase 0 and Sodium Current
  • Note the rapid "upstroke" characteristic of Phase 0 depolarization.
  • This abrupt change in membrane potential is caused by rapid, synchronous opening of Na+ channels.
  • Note the relationships between the the ECG tracing and phase 0
Ca2+:  Channel Activation Sequence similar to sodium; but occurring at more positive membrane potentials (phases 1 and 2)
  • Following intense inward Na+ current (phase 0), Ca2+currents:
  • Phases 1 & 2, are slowly inactivated.   (Ca2+channel activation occurred later than for Na+)

 

 

Channel Inactivation, Re-establishing the Resting Membrane Potential
  • Final repolarization (phase 3):
    • complete Na+ and Ca2+ channel inactivation
  • Increased potassium permeability
  • Membrane potential approaches K+ equilibrium potential -- which approximates the normal resting membrane potential

Influence of Membrane Resting Potential on Action Potential Properties

Hondeghem, L.M. and Roden, D.M., "Agents Used in Cardiac Arrhythmias", in Basic and Clinical Pharmacology, Katzung, B.G., editor, Appleton & Lange, 1998, pp 216-241.

Hondeghem, L.M. and Roden, D.M., "Agents Used in Cardiac Arrhythmias", in Basic and Clinical Pharmacology, Katzung, B.G., editor, Appleton & Lange, 1998, pp 216-241

Pathophysiology

Hondeghem, L.M. and Roden, D.M., "Agents Used in Cardiac Arrhythmias", in Basic and Clinical Pharmacology, Katzung, B.G., editor, Appleton & Lange, 1998, pp 216-241.

Introduction:  Arrhythmias and Drug Therapy 

Drugs assist in restoring and maintaining normal sinus rhythm include quinidine and procainamide

 

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How do Antiarrhythmic Drugs Work?

Antiarrhthmic Drug Classes

Class I Antiarrhythmic Drugs

Hondeghem, L.M. and Roden, D.M., "Agents Used in Cardiac Arrhythmias", in Basic and Clinical Pharmacology, Katzung, B.G., editor, Appleton & Lange, 1998, pp 216-241; Stoelting, R.K., "Cardiac Antidysrhythmic Drugs", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, 331-343

Hondeghem, L.M. and Roden, D.M., "Agents Used in Cardiac Arrhythmias", in Basic and Clinical Pharmacology, Katzung, B.G., editor, Appleton & Lange, 1998, pp 216-241;Stoelting, R.K., "Cardiac Antidysrhythmic Drugs", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, 331-343

Stoelting, R.K., "Cardiac Antidysrhythmic Drugs", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, 331-343

Stoelting, R.K., "Cardiac Antidysrhythmic Drugs", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, 331-343

Stoelting, R.K., "Cardiac Antidysrhythmic Drugs", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, 331-343

Class II: Beta-Adrenergic Antagonists

Hondeghem, L.M. and Roden, D.M., "Agents Used in Cardiac Arrhythmias", in Basic and Clinical Pharmacology, Katzung, B.G., editor, Appleton & Lange, 1998, pp 216-241; Stoelting, R.K., "Cardiac Antidysrhythmic Drugs", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, 331-343

 

 

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Class III: Potassium Channel Blockers

Hondeghem, L.M. and Roden, D.M., "Agents Used in Cardiac Arrhythmias", in Basic and Clinical Pharmacology, Katzung, B.G., editor, Appleton & Lange, 1998, pp 216-241; Stoelting, R.K., "Cardiac Antidysrhythmic Drugs", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, 331-343

Class IV: Calcium Channel Blockers

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